Applied Research in Esfahan Oil Refinery Company

(MSC & Ph.D. Thesis)

By Research & Development Office Department of Research & Development, Esfahan Oil Refinery Company, Esfahan, Iran Email: [email protected]

This Book is dedicated to Our Co-Worker

in Esfahan Oil Refinery Company those who are the best in my life

Applied research is necessary for progress and not to lag behind and not to stagnate in the fields of technology, industry, agriculture, medicine, culture and politics. In the meantime, any government that can base its decisions on the analysis and information of researchers and scholars, will certainly have a brilliant record and a defensible performance that the government of prudence and hope, has well understood this fact from the beginning, based its activities and practices on research. On the other hand, commercialization of science and production of wealth from scientific findings and meeting the needs of society through the relationship between university and industry and having applied research to serve the people are among the effective measures of research-oriented organizations. This is a fundamental category of the main pillars of human societies that if we focus and plan well, we will achieve positive results in society. Scientific work is one of the foundations of the strength and consistency of the country's cultural structure, which will promise the bright horizon of Iran tomorrow and the highway to self-sufficiency and all-round independence. Research, technology and entrepreneurship are the main axes of growth and development. Economic development and sustainable development are very important and its impact on current and future civilization is very clear and obvious, and the closer we get to recent times in human history, the greater this impact. We hope that by benefiting from valuable human capital and power, expertise and determination created at different levels, we can witness the significant development of the oil refining industry with international dimensions and standards.

Managing Director of Isfahan Oil Refinery

Content

Chapter Three 22

Chapter Four 32 Factors Affecting Ethical Leadership

Chapter Five 38 Consequences of Ethical Leadership

Chapter Six 57 Conclusion References 60

Company Contact Information Address: Isfahan, km 5 of Tehran road, postal code 8335113115 Mailbox: 415-81465 E-mail: [email protected] Scope of activity of the company (geographical): At the national level and if necessary, export abroad Website: www.eorc.ir

Isfahan Oil Refining Company Isfahan, the city of "rare artists and innovative painters", the city of art, culture and culture and today has one of the largest refining units in the country. Isfahan Oil Refining Company (EORC), has been operating in the field of crude oil refining and production of petroleum products and supply of feed for downstream industries (Isfahan Petrochemical Company, Arak Petrochemical Company, Sepahan Oil, Jay Oil Refining and Iran Chemical Industries) since 1979. It now produces about 23% of the country's petroleum products. This company is located in an area with a total area of 340 hectares and having a green space with an area of 114.5 hectares, in the northwest of Isfahan. Isfahan Oil Refining Company (EORC), has witnessed many improvements over the years, so that in the early 80s, the company's crude oil refining capacity increased by 85% compared to its design capacity, from 200,000 barrels per day to more than 375000 barrels per day. The crude oil required by Isfahan Oil Refining Company is supplied from Maroon oil field in a distance of 70 km from Ahvaz (Khuzestan Province), through 7 pressure boosting stations and a 430 km long pipeline. This huge industrial unit, in line with the strategic orientations stated in the company's policy, simultaneously with the implementation of a huge and strategic plan to improve the process and optimize the Isfahan refinery according to environmental objectives, increase the quantity and quality of products and profitability. The company, quality management systems, environmental, occupational safety and health and energy management based on the latest version of the international certification standards for quality management systems (ISO 9001), quality management system for product and service supply organizations for the petroleum, petrochemical and natural gas industries (ISO/TS 29001), environmental (ISO 14001), and safety management Occupational health (ISO 45001), the energy management system (ISO 50001) and operates under an integrated management system.

In 2007, Isfahan Oil Refining Company, having more profitability and productivity than other refining companies, as one of the leading oil centers in the huge oil industry of the country, was subject to Article 44 of the Constitution and by offering its shares in the stock market and transferred to the private sector. This large refining complex has three distillation units of 120,000 barrels, the main operating units of which are: ➢ Distillation Units (CDU), ➢ Liquefied Petroleum Gas Production (LPG), ➢ Viscosity Reduction (VIS), ➢ Catalytic Conversion (CRU), ➢ Hydrogen Production (H2), ➢ Isomax (ISM), ➢ Special Solvents (SSU), ➢ Control units 3 (SRP), ➢ Gasoline Production Complex (NHT, CCR, ISO).

Production of the Company Gasoline / Kerosene / Gas Oil / Furnace Oil / Liquefied Petroleum Gas / Raw Oil/ Special Solvents / Sulfur / Aircraft Fuels and other petroleum products.

First Category: Main Products (Special) The main products include: five liquefied petroleum gas products, gasoline, kerosene, gas oil and furnace oil, which are sent to the National Petroleum Products Distribution Company for distribution.

Second Category: special products with the aim of delivering to major customers Isfahan Oil Refining Company plays an important role in the country's economy as a feed supplier for five large production companies. Vacuum baton, special kerosene, naphtha, platform and base oil as special products that form the feed of

Jay Oil Companies, Iranian Chemical Industry, Arak Petrochemical, Isfahan Petrochemical and Sepahan oil Company.

Third Category: special products for small industrial Isomax kerosene, Isomax gas oil, Naphtha, Solvents, Iso-recycles, Light and Heavy base oils, Vacuum Bottom, Sulfur

Supply of Special Products in Iran Commodity Exchange Currently The following products are continuously offered in the Iran Commodity Exchange Hall: 1- Iso-recycle: in paraffin and cosmetics industries 2- Vacuum bottom: which is the raw material for preparing bitumen 3- Heavy Lub-cat: The raw material for the production of various lubricating and industrial oils is the feed of oil mills. 4- Sulfur: the raw material of acid making and agriculture industries 5- Types of solvents: 1-5) Special solvent 400: aromatic solvent is used as a diluent in alcohol, paint and printing industries. 2-5) Solvent 402: It is used in thinning, dyeing and wax industries. 3-5) Solvent 403: Used in textile industry and as a degreaser in metal industry. 4-5) Solvent 406: Used in chemical and cosmetic industries and in food industries. 5-5) Solvent 409: is a diluent of adhesives and thinner ingredients. 6-5) Solvent 410: In rubber and paint industries and resin and adhesives industries 7-5) Solvent 502: Used in Kerosene-based hydrocarbon industries as additives. 8

8-5) Solvent 503: Used in gasoline-based hydrocarbon industries as additives.

Main Vision Horizon 2026, Isfahan Oil Refining Company, will be one of the successful petroleum holding holdings in the country.

Major Projects Have Been Implemented and Are Being Implemented by the Company Process improvement and optimization plan of Isfahan Oil Refining Company (EORC): A) Plan Goals ➢ Reducing the refinery crude oil feed and stabilizing its capacity from 376 thousand barrels to 360 thousand barrels per day and protection of the country's national reserves ➢ Reducing the refinery's need for octane boosters such as super imported gasoline, etc. ➢ Increase the production of light products, especially gasoline, and reduce the production of heavy products (fuel oil) by using new technologies, including: ✓ Increase gasoline production from 8 million liters to about 20 million liters per day, ✓ Increase liquefied natural gas production from 17,000 to 29,500 barrels per day, ✓ Increase gas oil production from 108,000 to 120,000 barrels per day, ✓ Removal of sulfur from the refinery diesel, ✓ Improving the quality of refinery products in accordance with Euro standards to meet the needs of the country, ✓ Reduction of environmental pollutants, 9

✓ Production of new products including propylene and super gasoline.

B) Important Projects Implemented from the Project ➢ Construction of a third distillation unit and liquefied gas The third distillation and liquefied gas unit is one of the important projects of the refinery optimization and maintenance plan, which was put into operation in July 2017 with the efforts of local experts. With the commissioning of this unit, the capacity of the refinery was stabilized at 360 thousand barrels per day. Kerosene has increased. Other achievements of this project include improving the quality of kerosene produced in order to produce jet aircraft (ATK) fuel, producing a significant portion of the gasoline unit feed and producing part of the RHU unit feed. ➢ Construction of sulfur granulation unit The construction of a sulfur granulation unit in order to improve the performance and achieve the environmental goals of the company, is included in the optimization plan and maintaining the capacity of the refinery. This unit was commissioned in the summer of 2019 with a nominal capacity of 15 tons per hour and currently converts all the sulfur produced by the refinery, which is about 100 tons per day, into granular sulfur. The unit is designed in such a way that after the service of the diesel refining unit, all 300 tons of sulfur extracted from the refinery are converted into granules. ➢ Construction of Gasoline Production Plant (G.P.P) The project includes the construction of three units: NHT (Naphtha Purification), CCR (Continuous Catalytic Reforming) and isomerization (ISOM). With the help of His 10

Excellency, NHT and CCR units were launched in 2013 and put into operational service. However, due to sanctions, the supply of catalyst required for the isomerization unit was faced with problems and delays. This catalyst is one of the most strategic catalysts needed for oil refining and until then it was the monopoly of only two countries in the world, fortunately, and finally capable domestic specialists succeeded in producing it. Following this happy event, in February 2015, with the presence of the head of the country's environmental organization, managers and national and provincial officials, the gasoline complex was officially put into operation, during which the company produced about 11 million liters of Euro 4 gasoline per day. Delivers to the distribution company for distribution in Isfahan and other cities. Also, Isfahan refinery has been able to produce 2 million liters of Euro 4 diesel per day by making arrangements and software changes in the operating units. Of course, with the completion of the diesel refining unit project in 2021, it will offer all 22 million liters of daily diesel production to its compatriots with the Euro 5 standard.

C) Future Projects ➢ Launching a diesel refining unit The construction of this unit in order to increase the quality of diesel products with an environmental approach is on the agenda of the master plan. ➢ Construction of hydrogen treatment unit for residual distillation towers (RHU) The purpose of constructing this unit is to improve the quality of heavy products produced by the refinery. The engineering 11

activities of the project started in 2019 and according to the project schedule, it will be put into operation within 4 years. With the commissioning of this unit, the remains of the distillation towers will be refined and fed to the RFCC unit. Also, considering the quality of the unit's output product and compliance with current world standards, its export will have economic and commercial justification. ➢ Construction of RFCC unit This unit has been included in the refinery process improvement and optimization project projects with the aim of protecting national resources and preventing the sale of raw materials. With the launch of this project, the refined product of the RHU unit will be converted to gasoline and other inter- distillation products.

Projects Related to Maintaining Capacity and Improving Refinery Operations ➢ Construction of two 227-ton boilers and DM water ➢ Construction of loading platforms for petroleum products and their communication lines to the existing units of the refinery ➢ Design, construction and installation of substation 230/33 and construction of high-pressure transmission line ➢ Construction of pumping station and Shahinshahr wastewater treatment system ➢ Production of hexane from hydrocarbon cuts leading to Gasoline pool ➢ Construction of utility of internal projects ➢ Construction of natural gas pressure reduction station, process improvement plan and optimization

Ongoing Projects ➢ Reconstruction of cooling towers ➢ Design, purchase and installation of economizers and super heaters on boilers ➢ Construction of LPG recovery system from the exhaust gases of the isomerization unit

Other Important and Strategic Plans of the Company (Future Plans) The board of directors of the company is determined to serve the community and the development and increasing progress, with the guidance and support of esteemed shareholders, while maintaining and promoting the core values of the company, to achieve the following targeted strategies: ➢ Investing in the value chain of petroleum products ➢ Promote business capacity, improve customer satisfaction, employees and other stakeholders ➢ Quantitative and qualitative improvement of products, optimization and modification of processes, optimal use of resources in order to modify the consumption pattern ➢ Prevention of environmental pollution ➢ Managing and improving the technical knowledge of employees, promoting a culture of participation and teamwork in order to achieve organizational goals and increase productivity ➢ Effective interaction with neighboring industries ➢ Development of information systems, deployment and implementation of applications in various operational and management areas

Acquiring the title of leading company and second place in sales among the top 500 companies in Iran (IMI-100) - 2019 and first place in the group of petroleum products

Research and Development / Summary of Implemented Student Projects

Title Evaluation of Failure and Estimation of Remaining Life of Furnace Tube and Application of Neural Networks

Information Master Degree in Mechanical Engineering

Abstract Tubes are a type of equipment used in various furnaces, including boilers, super heaters, and furnaces in the oil and petrochemical industries. Their most important applications in power plants are industrial factories. Most tubes are made of chromium-molybdenum alloy steels. These alloys are able to maintain their strength at high temperatures. The tubes operate under high temperature-stress operating conditions. These working conditions cause various destructive mechanisms such as creep, fatigue, corrosion and oxidation to be applied to the tube, and as a result, the tube deteriorates over time. In fact, the importance of estimating the remaining life becomes apparent when we want to use one piece longer than the design life. In this research, the defective tube of a furnace in the distillation unit of Isfahan refinery has been studied from a mechanical and metallurgical point of view. First, since the reason for the exhaustion of the sample was the overheating of one side of it due to the formation of a layer of sediment on the inner wall, all studies were performed in two parts. For both sections, first the possible physical and metallurgical changes were investigated and their results were compared and analyzed with standard values. Second, the increase in temperature created in the tube

15 due to the formation of the sediment layer was analyzed by finite element software, and then a three-dimensional model was developed to analyze the stress and creep deformation. Finally, the estimation of tube life for each part was performed by a computational method based on temperature and stress obtained from the analysis. A neural network was trained to estimate the rate of temperature increase, deformation and stress on both sides of the tube based on the thickness of the sediment layer. Physical and metallurgical tests showed that the overheated side of the tube did not undergo any physical or metallurgical properties and no cracks or cavities were found in the structure. The results of the stress-rupture test were in accordance with the results predicted by the standard. The results of the experiments on the overheated side indicate that the creep phenomenon is very advanced in this part, the time spent for stress-rupture test in this part was shorter than the amount predicted by the standard and also the microstructure of the metal has changed. The results of thermal analysis showed that with 10 mm of sediment thickness, the temperature of the metal near the sediment increases up to 801 oC . The results showed that the stresses created on the overheated side are far more than the other sets, and at the same time both of these stresses are greater than the value obtained by the formula provided in the API standard. This is due to the addition of thermal stresses and stresses due to deformation of the tube. The resulting deformation is very close to the observations reported in the recorded overhaul of the furnace. The results obtained from the neural network are very close to the finite element analysis values with very close estimates.

Description Methods for estimating the remaining life of parts are very useful if the factories are shut down for a long time. In factories, there are some non-sensitive parts that can be repaired or replaced in the event of damage during operation, and the factory will continue to operate until the next shutdown. However, some sensitive and vital

16 equipment such as turbine blades, pressure vessels, boilers, etc. in case of damage, damage the whole set and affect the performance of the factory. In general, life estimation methods can be divided into three main levels. First- level methods are generally used when the service life of components under service is less than 80% of their designed life. In level one, estimation is performed using workshop statistics and equipment, design stress and temperature, and the minimum values of material properties. Level 2 methods are used when component life exceeds 80% of design life. This level includes the actual measurement of dimensions and temperature, calculation of stress and inspection of the part and the use of the minimum allowable values of the desired part. But when the life of the part exceeds the designed life, level three methods are used. This level includes pit inspection, stress analysis, equipment monitoring, and obtaining factual information from samples isolated from components, and mainly performing destructive tests . The detail and accuracy of the results will increase from level one to three, but at the same time the cost of estimating life will increase. Depending on the amount of information available and the results obtained, the analysis may be stopped at any of the levels or upgraded to the next level, if necessary. Methods for predicting crack onset include calculations, non-destructive assessments, and destructive assessments. The choice of any method is based on the mechanism of failure, ie creep, fatigue or their combination. Knowing how the useful life spent on a part is necessary to prevent damage to the part during operation and designing replacement times for the part in question, and it is also possible to have an accurate time interval for inspecting, repairing and renewing the part. The opinion was obtained, thus reducing the cost of consumable parts. The sample studied in this research is H-101 furnace tube, one of the distilleries of Isfahan refinery. This furnace heats the crude oil to enter the distillation tower from ambient temperature to about 480 oC. The temperature of the crude oil at the furnace outlet must always be constant at 480 ºC, although according to the refinery policy the amount of furnace feed (and consequently the furnace outlet) may vary throughout the year. 17

This furnace is currently in heavier working conditions than the furnace design conditions in service. The material of the tube used in it is 9 Cr-1Mo. The burners of this furnace have been fossil fuel in the past, but over the past few years they have been changed to gas burners to reduce the problems caused by flame corrosion in these pipes. This cell consists of two walls, east and west. Each wall has 30 rows of tubes numbered from 1 to 30 and 12 rows of tubes are placed in the roof of this cell according to the figure. Each cell has two inlet passes that pump crude oil into the tubes. Inputs E, F, G and H also belong to the western cell, which has a total of 8 inputs in this furnace. The outlets of the furnace in each wall are from tubes 15 and 16, which are marked in black. At present, the average feed of 14,300 barrels per day of crude oil enters this furnace through the mentioned 8 inlet passes. In other words, 2845125 liters of crude oil passes through each pass of this furnace daily and its temperature at the furnace outlet reaches about 480 oC.

Result and Discussion Theoretical observations and measurements made on the tube show a very small difference with the values of the new tube that these small differences are within the allowable range. The outer and inner diameters and the thickness of the tubes do not all exceed the standard values. The thin black layer of the inner surface, which is easily removed from the surface, is not a special issue. The results of chemical analysis performed on the sample indicate that all the alloying elements of these tubes are in the range specified in the ASTM standard and no differences are observed. ASTM A106 does not specify a range for the hardness of the alloy, but ASTM A200M specifies the maximum allowable hardness for the alloy of this tube is 179 Brinell. For the tube in question, which is made of A200 T9 alloy, the average hardness number is 81.7 Rockwell B, which is approximately equal to 152 Brinell, which indicates that the hardness is appropriate compared to the standard. Comparison of the results obtained for the samples with the standard values indicates that all the tensile properties of this tube are in accordance with the standard. In sample number 2, the relative elongation is very slightly less than the 18 minimum standard, which is due to the breaking of the sample near the gage line, and in this regard, there is no problem. Examining the microstructure of metallographic samples, it is observed that no significant changes have occurred in the microstructure of this tube. Or there are changes in very small size and do not have much effect on the properties of the metal. In stress-rupture tests performed on different samples, it is observed that all samples have the minimum creep resistance according to API SDT 530 standard.

Conclusion The pipes are used in power plants, industrial plants such as oil and petrochemicals. Most tubes are made of chromium-molybdenum steels, which are mainly from the three families 2.5 Cr-1Mo or 1.25 Cr-0.5Mo or 9 Cr-1Mo. These steels are able to maintain their strength at high temperatures. Generally, this type of steel is used at high temperatures where its creep resistance is improved by the addition of molybdenum and chromium, and its corrosion resistance is improved by the addition of chromium. The tubes operate in critical temperature-high stress operating conditions. These working conditions cause various destructive mechanisms such as creep, fatigue, corrosion and oxidation to affect the furnace tube, and as a result, the tube deteriorates over time. The most important causes of tube failure include: overheating, flame corrosion, and graphitization due to carbide deposition in the grain boundaries. The issue of estimating the life and optimal use of the components of furnaces, boilers and super heaters is of particular importance. In this research, the replaced tube of a crude oil heating furnace in the distillation unit of Isfahan Oil Refining Company (EORC) has been studied from a mechanical and metallurgical point of view. The reason for the destruction of this tube was the overheating of one side of it due to the formation of a layer of coke deposition on its inner surface. For this purpose, in order to compare the two sides of the tube, all tests and analyzes related to estimating the remaining life were performed on both sides of the tube.

First, quantum tests, hardness tests, tensile tests and stress-tear tests were performed on samples prepared from these two sides. The results of physical and metallurgical tests showed that on the overheated side of the tube, the physical and metallurgical properties did not change and no traces of cracks or cavities were seen in the structure. The results of the stress-rupture test were in accordance with the results predicted by the standard. The results of the experiments on the overheated side indicate that the creep phenomenon is very advanced in this part, the time spent for stress-rupture test in this part was shorter than the amount predicted by the standard and also the microstructure of the metal has changed. Examining the carbides formed in this area, it was observed that the type of carbides formed, based on the results of other researchers, is within the range of the final changes predicted for this type of steel due to creep. Second, the uneven outer surface and the graphitized inner surface were other differences between this side of the tube and the other side. All the available evidence indicates that the tube is malfunctioning under the operating conditions. In order to more accurately investigate the overheated side, first a two-dimensional model of the tube and sediment formed by ABAQUS software was prepared and the temperature increase due to different thicknesses of sediment to the maximum measured thickness of 10 mm was obtained. Came. It was observed that with this deposition thickness, the temperature of the metal close to the deposition increased up to 801 oC . Third, a three-dimensional model of this part with dimensions according to the furnace map was created in this software and by applying the initial and boundary conditions appropriate to the operation of the tube in the furnace, stress analysis and deformation on this part with increasing area temperature more than the heating limit was performed. The results showed that the stresses created on the overheated side are far more than the other sets, and at the same time both of these stresses are greater than the value obtained by the formula provided in the API standard. This is due to the addition of thermal stresses and stresses due to deformation of the tube. The resulting deformation is very close to the observations reported in the recorded overhaul of the furnace. 20

Finally, based on the results, a neural network was trained to estimate the maximum temperature created, the maximum creep deformation and the maximum stress on each side of the tube with the input of the thickness of the sediment layer. Based on the obtained results, the following conclusions can be made: 1. The overheated side has a significant residual life if the tube life on the other side is almost over . 2. The carbides formed on the overheated side have changed, their amount has increased, they have become larger, and new M6C carbides have been formed. 3. By performing temperature analysis in ABAQUS software, the maximum temperature caused by coke deposition on the inner surface of the tube has reached 801 oC. 4. The critical point of temperature resulting from the formation of sediment is near the outer surface of the tube and under the sediment formed. 5. The results of stress analysis of the three-dimensional model of the tube showed that the stress generated on the overheated side is higher than the other side, and both of these stresses are greater than the value obtained from the formula proposed in the API standard for estimating stress. 6. Analysis of creep deformation caused by software showed that the deformation is in the form of bending upwards and its maximum is approximately 68 cm and is close to the value reported when replacing the tube. 7. Considering the estimated creep life, the remaining life of the tube on the overheated side is about 84,000 hours and the overheated side is only 37 hours. 8. With the help of neural networks, we were able to estimate the increase in temperature, stress and creep deformation in terms of

increasing the thickness of the sediment layer. An error of less than 5e × 1 was obtained.

Figures and Tables

Figure 1. Microstructure of mid-section tube, viella etching solution (X200)

Figure 2. Microstructure of mid-section tube, viella etching solution (X500)

Figure 3. Microstructure of inner surface tube, viella etching solution (X100)

Figure 4. SEM image formed to investigate the type of carbide

Figure 5. Temperature profile in a tube with a deposition thickness of 3 mm

Figure 6. Tension created in the tube at a deposition thickness of 10 mm

Figure 7. Location of the most stress on the overheated side and its amount

Figure 8. Location of the most stress on the overheated side and its amount

Acquisition of the title Acquisition of the title of the leading

company and the third place in sales among the top 500 companies in Iran (IMI-100) - 2018 and the first place in the

group of petroleum products

Research and Development / Summary of Implemented Student Projects

Title Synthesis of nano-hole zeolites A, X and Y to remove sulfur compounds from oil slices

Information Master Degree in Chemical Engineering

Abstract In this study, the structure of zeolites A, X and Y, their synthesis and ion exchange were studied and the mentioned zeolites were synthesized. Using ion exchange method, the required adsorbents were prepared from synthesized zeolites and copper salts. Using the prepared adsorbents, experiments related to the removal of mercaptan from two oil slices L-SRG and L-Naphtha from the products of Isfahan refinery are performed in a batch reactor and the results are presented. Zeolites A, X and Y are important attractions in sulfur removal that have been used in this research. By exchanging divalent copper ions instead of sodium ions in the mentioned zeolites, their ability to remove sulfur has been increased. Percentage of copper ion exchange, adsorbent mass for a certain amount of oil cut and contact time are three parameters affecting the process. In this research, the response behavior against the change of each of these parameters at 10 °C is investigated and presented. Using Taguchi experimental design method, the number of experiments for each oil cut was minimized and 4 levels were selected for each parameter, which makes the L-16 orthogonal array. Using analysis of variance, the effect of each parameter on the percentage of removal of sulfur compounds was calculated. The simultaneous effect of the

26 parameters on the mercaptan removal percentage has also been investigated by contour diagrams. The results showed that in zeolite A, the parameter of copper exchange rate has the greatest effect on the percentage of mercaptan removal from L-Naphtha oil section. In L-SRG oil section, the zeolite mass parameter has the greatest effect. At low copper exchange rate, time and adsorbent mass are very effective on the percentage of mercaptan removal from both oil cuts, while at high copper exchange rate the effect of time parameter is less. In zeolite X, the effect of the parameters is almost the same for both oil cuts. In this zeolite, the parameter of copper ion exchange percentage has the greatest effect in both oil cuts. It seems that the large pore size and the number of cations in zeolite increase the effect of the copper ion exchange rate parameter on the removal of mercaptan. The maximum percentage of mercaptan removal is obtained in the maximum values of time and mass of the adsorbent, where the double effect of these two parameters is observed. Zeolite Y has a higher adsorption capacity than zeolites A and X. At low copper exchange rates, adsorbent time and mass affect the percentage of mercaptan removal. But at high copper exchange rates, their effect is less. In both oil fields, the highest percentage of mercaptan removal is when the level parameter of copper ion exchange percentage is low and the level of adsorbent mass and time parameters is high.

Description The main purpose of modern refineries is to produce higher value-added products than crude oil using chemical and physical processes. According to the rules, the removal of pollutants such as sulfur compounds is one of the most important factors in the production of clean fuel. A review of the work done in the use of zeolite in desulfurization Extensive efforts have been made to develop new adsorbents to remove sulfur compounds from oil fields. According to environmental laws, new technologies have been used to treat light petroleum cuts such as naphtha. Sulfur is released on the adsorbent and 27 hydrocarbons are released without sulfur. By exchanging ions on adsorbents such as zeolites, the activity of adsorbents can be increased. Intermediate metals can increase the chemical activity of adsorbents. The cavity size and electronegativity of cations play an important role in chemical adsorption. Also, to increase the effectiveness of the adsorbent, one should be careful in ion exchange, determining the type of adsorbent, pressure, temperature and even the adsorbent center. It is very interesting to study the diffusion processes in zeolites. Because these crystals have very regular internal surfaces and they are used in most large industries. It is possible to use the adsorption process for selective removal of sulfur-containing organic compounds of the burn at room temperature and pressure. In recent decades, the improvement of industrial and commercial attractions has grown significantly. Technologies such as S-Zorb from various companies seek to completely eliminate sulfur in oil. Another new technology is our ultrasonic method and the use of ultraviolet light. Initially, bauxite was used to remove sulfur, especially mercaptans, from oil slices. With the synthesis of new zeolites, the technology for the production of industrial catalysts grew rapidly. Using these catalysts at high temperatures and under hydrogen pressure, the adsorption of organic sulfur compounds was greatly increased. In the process known as S-Zorb, sulfur atoms are separated from cyclic aromatic compounds and the sulfur atom adheres to the adsorbent surface. Popular adsorbents such as activated carbon, activated alumina and zeolites have the ability to remove sulfur. Zeolites such as 5A, 13X and Y and ion exchange zeolites have the ability to selectively remove sulfur. Rapid and excessive filling of the adsorbent cavities with heavy sulfur compounds reduces the amount of adsorption. However, by increasing the adsorbent to feed ratio or by accelerating the synthesis of adsorbent reduction reactions, this limitation is removed. Zeolites are materials that exist both naturally as clinoptilolite and synthetically as zeolite X and Y. These materials were first discovered and identified in 1756 by a Swedish miner named 28

Baron Cransted. The name zeolite is based on the fact that when heated, a large amount of water is released as steam. By definition, zeolite is a crystalline aluminosilicate with a quadrilateral structure and enclosed in pores occupied by cations and water molecules, both of which have sufficient freedom to move ion- exchange and reversibly lose water. Due to the crystalline structure with microscopic pores in zeolites, these materials are unique attractions. Although so far more than 40 types of natural zeolites and 150 types of synthetic zeolites have been discovered and identified, but only a few of them have been used as adsorbents. Zeinite Clinoptilolite is the most abundant natural zeolite, often found in sedimentary rocks of volcanic origin. Depending on the region there, some of the sodium or potassium cations in it may have been replaced by cations such as calcium and barium or other cations. This type of zeolite can withstand temperatures between 700 and 800 degrees Celsius and its structure does not change much. The ratio is between 5 and 6 and has high stability in acidic and alkaline environments. The rings in its structure are 8 and 10. Many applications have been reported for natural zeolite clinoptilolite, including drying gases, adsorption of gases such as, and separation of radioactive materials from effluents, and as a catalyst in isomerization processes in petrochemicals. Zeolites are synthesized with aqueous solutions at temperatures between 70 and 300 ° C under the spontaneous pressure of the system, which is usually close to the water vapor pressure at that temperature. The type of zeolite obtained depends on the production conditions. These aqueous solutions contain the necessary chemical components such as sodium aluminate, sodium silicate and sodium hydroxide. The time required to produce zeolites varies mainly from a few hours to a few days. It goes without saying that in recent years scientists have been able to reduce this time to one minute by using microwave technology and create a great change in the synthesis of zeolites. Zeolites are prepared in the form of crystalline powders and usually in the size of crystals less than 10 microns.

Chemicals Used Removal of mercaptan from two petroleum cuts of gasoline from the atmospheric tower (L-SRG) and light naphtha (L-Naphtha) from the Izomax tower, including the initial mercaptan of 30 and 20 ppm, respectively, from Isfahan refinery products have been investigated. Most oil cut components are composed of normal and branched alkanes (about 75 to 85%). Aromatic and petroleum compounds such as benzene, toluene and cyclopentane together make up 15 to 25% of the oil fraction.

Synthesis of Zeolite (Linde Type A) LTA In this method, sodium metasilicate was used as a source of silicon, sodium aluminate was used as a source of aluminum, sodium hydroxide and water were distilled twice. To prepare zeolite A, first, empty and dry human propylene was added to which 0.723 g of net profit and 80 ml of water were added to dissolve. The solution was then divided into two equal parts. To one part of this solution, 8.258 g of sodium aluminate was gradually added to dissolve. The solution seemed slightly cloudy due to the insolubility of a very small amount of sodium aluminate, but then the solution became clear with a uniform stirrer. The stirring time of the solution in a closed human is about 10 to 20 minutes. To the other part of the solution was added 15.48 g of sodium metasilicate. The mixture was stirred slightly to homogenize. The stirring time of the solution was about half an hour. This time will be longer if the sodium metasilicate solution is crystalline. At the end of the stirring time, some unresolved solids remain. To dissolve them, we have to warm the human body a little to dissolve the remaining sodium metasilicate. Then the prepared sodium metasilicate solution was quickly added to the prepared sodium aluminate solution and a white gel was formed. The molar ratio used in the preparation of LTA zeolite primary gel is as follows: The weight ratios of the components used were generally based on the Thomson and Haber method. For homogenization, the resulting gel was stirred on a high-intensity magnetic stirrer for 5 to 10 minutes and then transferred to a Teflon reactor at 99 1 1 oC. The Teflon reactor is sealed and the gel does not stir. 30

After 3-4 hours, the reactor was taken out of the oven. After the reactor had cooled to below 30 °C, the reactor contents, which included the clear liquid phase and the solid zeolite phase, were vacuum filtered by the Buchner funnel and Whatman filter paper. The solid part, which is the same as zeolite, was washed with a large amount of deionized water until the pH of the filtered water reached less than 9. The zeolite was then placed in a dryer overnight at 110 °C to dry. It should be noted that the molar ratio of the components is synthesized in LTA zeolite. The temperature used in the crystallization of zeolite A was 100 °C and the crystallization time was about 3 to 4 hours. Of course, the temperature used can vary in the range of 60 to 110 degrees Celsius and its crystallization time can vary depending on the temperature used. It should also be noted that the crystallization time should not be prolonged because longer times can lead to the formation of P phase impurities in the synthesized zeolite A. The size of the crystals is about 2-3 micrometers and the crystals are cubic.

Preparation of Zeolite (Low Silica Type X) LSX In this method, sodium silicate solution was used as a source of silicon, sodium aluminate as a source of aluminum, sodium hydroxide, potassium hydroxide and deionized water. The molar ratio used in the preparation of the initial zeolite X gel is as follows: To prepare LSX zeolite, first two solutions A and B have been prepared as follows. Solution A: First, the polypropylene was weighed and 9 g of sodium aluminate and 30 g of water were added to it. The solution was stirred until complete dissolution of sodium aluminate. Solution B: In a polypropylene human, 8.88 g of potassium hydroxide plus 13.0336 g of sodium hydroxide was dissolved in 18.442 g of water. Then the sodium aluminate solution prepared in Part A was added suddenly and rapidly to solution B. It should be noted that solution A should be completely transparent, but if it is cloudy, it should be clear after adding solution B to it. The resulting solution was then mixed with 29.156 g of water and 20.2134 g of sodium silicate solution and stirred 31 rapidly. After a few minutes of stirring vigorously, a white gel appeared. For crystallization, the gel was transferred to a Teflon reactor and incubated in an oven for 3 hours at 70 °C without stirring. After this time, the oven temperature was set at 100 and after 2 hours, LSX zeolite crystals were formed without stirring. The contents of the reactor, which consisted of a clear liquid phase and a solid zeolite phase, were diluted with deionized water. It was then vacuumed with a Buchner funnel and Whatman filter paper. Zeolite X was washed with a large amount of 0.01 N NaOH solution during filtration. The zeolite was then placed in a dryer at 110 °C for 12 hours to dry. The molar ratios of the components used were generally based on the Koohl method. The molar ratio of synthesized LSX zeolite is as follows:

Preparation of Zeolite Y (Linde Type Y) In this method, sodium silicate solution was used as a source of silicon, sodium aluminate as a source of aluminum, sodium hydroxide, potassium hydroxide and deionized water. In the preparation of zeolite Y, two separate solutions were made, one gel core containing 5% aluminum (gel with initial molar ratio) and the other gel containing 95% aluminum (gel with initial molar ratio). This method is very fine only for the production of NaY crystals and is limited in a certain range of size and composition percentage. To prepare the gel core, 50 ml of polypropylene was first emptied and 0.75 g of sodium aluminate with 1.91 g of caustic soda and 5.83 g of water were added to dissolve it. The solution was then stirred. The resulting solution seemed slightly cloudy due to the small amount of water. Then 7.657 g of sodium silicate was added to the solution and stirred for at least 10 minutes. After stirring, the human lid was closed and kept at room temperature for 1 to 5 days. The closer the life of the gel core solution is to the fifth day, the more selective the composition percentage, in other words, the purer the resulting zeolite. After a few days of the gel core life, the gel solution was made. First, human 500 ml polypropylene was emptied and dried. 4.7017 g of sodium aluminate was added to it along with 0.5564 g of pure sodium hydroxide in 36.233 g 32 of water. The solution was stirred at room temperature until complete dissolution. Sodium silicate solution was then added and stirred vigorously. A white, homogeneous gel formed. At the beginning of gel formation, the stirring power should be increased because at this time the shear stress is high. To prepare the final gel, all the gel solution was gently added to 49.2343 g of the gel core solution. Here the shear stress of the gel was very high and the solution was gently stirred for more than 20 minutes.

The Resulting Gel has an Initial Molar Ratio The human polypropylene lid was then closed and the gel was stored at room temperature for one day. During the incubation stage, the gel was gently stirred. After this step, the gel was transferred to a Teflon reactor and crystallized in the oven for 22 hours at 90 °C without stirring. The reactor content consisted of a clear liquid phase and a solid phase of zeolite which indicated complete crystallization. In the next step, the solid phase and the liquid phase were separated from the zeolite solid for 20 minutes using a centrifugal at 2000 rpm and filtered under vacuum with a Buchner funnel and Whatman filter paper. Zeolite was washed twice with a large amount of distilled water to bring the pH of the filtered water below 9 °C. The zeolite was then placed in a dryer at 110 °C for 12 hours to dry.

Investigation of the Effect of Parameters on Zeolite A In the experiments, the effect of three important parameters of copper ion exchange level, zeolite mass and contact time on the amount of mercaptan removal in L-SRG and L-Naphtha oil sections were investigated separately. The results show that the percentage of mercaptan removal is higher in L-Naphtha oil section. At low copper exchange rate, time and adsorbent mass are very effective on the percentage of mercaptan removal. But at high copper exchange rate, the effect of time parameter decreases.

Investigation of the Effect of Parameters on Zeolite X In these experiments, the effect of three important parameters of copper ion exchange level, zeolite mass and contact time on the percentage of mercaptan removal in L-SRG and L-Naphtha oil cuts were investigated separately, the results of which show that the percentage of mercaptan removal in L-oil cut -Naphtha is more. The effect of copper exchange rate parameter on both oil cuts is more than the other two parameters. At low copper exchange rates, contact time and adsorbent mass affect the percentage of mercaptan removal. But at a high level of copper exchange, their effect is less. At a copper exchange rate below level 1, the mercaptan removal percentage decreases due to the lack of copper ions. In both oil cuts, the highest percentage of mercaptan removal is when the copper ion exchange percentage parameter is at level 1 and the adsorbent mass and contact time parameters are at level 4. The results show that the mass of zeolite X per volume of oil cut has a higher adsorption capacity than zeolite A. The structural shape, pore size and number of cations in zeolite X increase the adsorption rate. Among Fujasite zeolites, LSX zeolite contains the highest cation location. In zeolite X, site I is often occupied by ions. However, in LSX zeolite with a ratio of 1, site III is also occupied by monovalent cations. The cations at sites I, I 'and II' are not available for reaction with adsorbed molecules other than the water molecule. In other words, almost half of the cations do not participate in the adsorption. In zeolite X, the cations at site I are exchanged in very hard hexagonal prisms. Larger cations are located at sites that can easily enter their cavities. Sites II and III contain available oxygen rings of six and four, respectively, and participate in the reaction with organic molecules. Alkali metals occupy both sites II and III, and divalent metals such as copper are often located at sites II and I.

Investigation of the Effect of Parameters on Y Zeolite In these experiments, the effect of three important parameters of copper ion exchange level, zeolite mass and contact time on the percentage of mercaptan 34 removal in L-SRG and L-Naphtha oil cuts were investigated separately, the results of which show that the percentage of mercaptan removal in L-oil cut -Naphtha is more. The effect of the contact time parameter on both oil cuts is more than the other two parameters. In L-SRG oil section, the adsorbent mass parameter has a similar effect to the contact time parameter. But in L-Naphtha oil section, the adsorbent mass parameter has less effect on the mercaptan removal percentage. In both oil cuts, the highest percentage of mercaptan removal is when the copper ion exchange percentage parameter is at level 1 and the adsorbent mass and contact time parameters are at level 4. The results also show that zeolite Y has a higher adsorption capacity than zeolites A and X. Structural shape, pore size, position of cations in zeolite Y and how ions are exchanged in zeolite are factors that can increase the rate of adsorption. At low copper exchange rates, contact time and adsorbent mass affect the percentage of mercaptan removal. But at a high level of copper exchange, their effect is less. The location of cations in LSX zeolite is almost twice that of Y zeolite. However, in zeolite Y, most sites I 'and II are occupied by ions. Cations at sites I, I' and II 'are not available to react with adsorbed molecules other than water molecules. They exchange. The large cations at this site can easily enter its cavities and participate in the reaction with organic molecules. For this reason, with increasing percentage of copper ion exchange, most copper ions are located in accessible places. This phenomenon has caused that the copper ion exchange percentage parameter has little effect on the adsorption process. In the L-SRG section, the percentage of mercaptan removal decreases slowly with increasing copper ion exchange rate, while in the L-Naphtha oil section, it decreases first and then increases. The L-SRG fragment contains lighter compounds than L-Naphtha and due to their small molecular diameter, they can easily enter the zeolite cavity and react with the copper cation.

Conclusion In the hydro-sulfurization method, due to the use of catalysts, high temperature and pressure, some useful oil cutting compounds are lost, but in the method used in this project, due to the direct adsorption of sulfur compounds at low temperature and pressure, without any preliminary operations, the cutting tissue Oil is safe. Also, zeolites are not easily degraded due to their crystalline structure. This allows them to be used frequently and regenerated for reuse. According to the experiments performed to investigate the effect of three parameters of copper ion exchange level, adsorbent mass and contact time on the percentage of mercaptan removal from two oil fractions L-SRG and L-Naphtha, for zeolites A, X and Y the following results Was: ➢ The percentage of copper ion exchange in zeolites synthesized in this paper is less than 100%. If the measured copper ion exchange percentage is more than 100%, it indicates the deposition of copper ions on the zeolite surface and the closure of the cavities. Thus, despite the increase in the percentage of copper ion exchange in zeolite, the percentage of sulfur removal from the oil fraction is greatly reduced. ➢ At a very low copper ion exchange rate, due to the lack of copper ions in the active sites, the sulfur removal percentage decreases. ➢ Due to the presence of polar molecules and cyclic organic compounds such as benzene in the oil fraction, most of the adsorption capacity will be spent on the adsorption of such molecules and there will be no opportunity to adsorb large molecules containing sulfur. ➢ Zeolite A is not suitable for mercaptan compounds due to its small pore size. In zeolite A, the copper exchange rate parameter has the greatest effect on the percentage of mercaptan removal from the oil cut. It has L- Naphtha. In L-SRG oil section, the zeolite mass parameter has the greatest effect. In zeolite A, at low copper exchange rates, contact time and adsorbent mass are very effective on the percentage of mercaptan

removal. But at high copper exchange rate, the effect of the contact time parameter decreases. Z ➢ The effect of the parameters is almost the same for both oil cuts. In zeolite X, the parameter of copper ion exchange rate has the greatest effect. It seems that the large size of the cavity and the number of cations in zeolite increase the effect of the copper ion exchange rate parameter on the removal of mercaptan. ➢ In zeolite X, low copper exchange rate, contact time and adsorbent mass are effective on mercaptan removal percentage. But at a high level of copper exchange, their effect is less. The maximum removal of mercaptan is achieved in the maximum values of the parameters of contact time and adsorbent mass, where the double effect of these two parameters is observed. Zeolite Y has a higher adsorption capacity than zeolites A and X. ➢ The number and position of cations in zeolite Y are factors that can increase the amount of adsorption. At low copper exchange rates, contact time and adsorbent mass affect the percentage of mercaptan removal. But at a high level of copper exchange, their effect is less. ➢ In both oil cuts, the highest percentage of mercaptan removal is when the level parameter of copper ion exchange percentage is low and the level of adsorbent mass parameters and contact time are high. Unlike zeolites A and X, in zeolite Y the contact time parameter has the greatest effect on both oil cuts. Due to the position of the cations in zeolite, as the contact time increases, the amount of adsorption also increases.

Figures and Tables

11000

10000

9000

8000

) 7000

6000

Counts ( 5000

4000

Intensity Intensity 3000

2000

1000

0 5 10 20 30 2 (  40 50 60 ) Figure 1. XTA Spectra of Synthesized and

10000

9000

8000

)

7000

6000

Counts (

5000

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Intensity Intensity 3000

2000

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5 10 20 30 40 50 60 2 (  ) Figure 2. XRD Spectrum of Synthesized and Reference Y Zeolite

Figure 3. Schematic View of the Intermittent Surface Adsorption Reactor

100 90 80 70 60 50 40 30 20

Percent of Sulfur Removal Sulfur of Percent 10 0 0 1 2 3 4 5 Level of Cu% Figure 4. Graph of Mercaptan Removal Percentage in 400 ml of L-SRG Oil Section Relative to Copper Ion Exchange Level

100 90 80 70 60 50 40 30 20

Percent of Sulfur Removal Sulfur of Percent 10 0 0 1 2 3 4 5 Level of Solid Mass Figure 5. Graph of Mercaptan Removal Percentage in 400 ml of L-SRG Oil Cut to LTA Zeolite Mass

100 90 80 70 60 50 40 30 20

Percent of Sulfur Removal Sulfur of Percent 10 0 0 1 2 3 4 5 Level of Time Figure 6. Graph of Mercaptan Removal Percentage in 400 ml L-SRG Oil Slices with Respect to Time

40.0 80.0 60 60.0

t p

r 40

o 30

m i T 20

30.0 10

0.10 0.15 0.20 0.25 0.30 0.35 Solid Mass Figure 7. Simultaneous Effect of two Factors of Time and Mass of Zeolite X on the Percentage of Mercaptan Removal for L-SRG Oil Cutting

40.0 60

o i

t 60.0 p

r 40

o 30

m i T 20

20.0 10

0.10 0.15 0.20 0.25 0.30 0.35 Solid Mass Figure 8. Simultaneous Effect of Two Factors of Time and Mass of Zeolite X on the Percentage of Mercaptan Removal for L-Naphtha Oil Cutting

t p

r 40

o s

d 35

o 30

m i T 20 15 25 10

0.2 0.4 0.6 0.8 1.0 1.2 1.4 Solid Mass Figure 9. Simultaneous Effect of Two Factors of Time and Mass of Zeolite A on the Percentage of Mercaptan Removal for L-SRG Oil Cutting

60 80.0

n o

i 40.0

t p

r 40

o 30

m 60.0 i

T 20.0 20

0.2 0.4 0.6 0.8 1.0 1.2 1.4 Solid Mass Figure 10. Simultaneous Effect of Two Factors of Time and Mass of Zeolite A on the Percentage of Mercaptan Removal for L-Naphtha Oil Cutting

Acquisition of the title of obtaining the title of the leading company and the fifth rank of sales among the top 500 companies in Iran (IMI-100) - year 2017 and the first rank in the group of petroleum products

Research and Development / Summary of Implemented Student Projects

Title Optimization of catalytic conversion unit with continuous revitalization under the brand name of octaneizer of Isfahan Petroleum Refining Company through simulation with petroleum software to stabilize the production of gasoline with octane number

Information Master Degree in Chemical Engineering

Abstract The development of the automobile industry and the use of gasoline engines is an increasing trend that is causing a growing demand for high octane fuels. One of the most important characteristics and quality features of high-quality gasoline product, in addition to low levels of pollutants such as sulfur and benzene and aromatic compounds and lead and manganese particles, etc. is the degree of slow burning or octane number of fuels. One of the most important and key processes in refineries is the catalytic conversion of naphtha. This process mainly produces gasoline with high octane number and in expensive aromatic petrochemical complexes such as benzene, toluene and xylene. Due to the growing need and importance of quality and quantity of high-quality gasoline production, the need to optimize and improve the performance of Naphtha catalytic conversion unit in order to find the best amounts of operational variables, appropriate measures, solutions in the face of fluctuations, changes in process

42 conditions and identify bottlenecks and reducing production costs through simulation of the process seems necessary. In this research, first the processes leading to gasoline production and the reactions leading to increasing octane number in the catalytic conversion unit with continuous reduction of Isfahan refinery gasoline complex are explained and then simulated with Petrosim software and then with a comprehensive study of relationships and effects. All different operating variables and process conditions have been optimized to find the best values of the variables to produce high quality gasoline with 100 octane number in the nominal capacity of 30,000 barrels per day of Naphtha catalytic conversion unit feed and reduction of unit energy consumption. Finally, according to all researches and studies, the best proposed values of operational variables for the production of high quality gasoline in nominal capacity as described at 525 °C reactor inlet temperature, flow rate of 22 tons per hour of circulating gas with 93% hydrogen purity, flow rate of 800 kg Per hour of catalyst rotation, relative pressure of 5.5 times the output of the circulating gas compressor, concentration of 0.9% by weight of the catalyst chloride, temperature of 261 °C, outlet of the stabilizing tower and temperature of 155 °C and relative pressure of 1.5 times of the bottom of the tower The naphtha hydrogen treatment unit separator was obtained, which resulted in the production of 25,630 barrels per day of gasoline product with 100 octane number and 0.37% by volume of benzene. The mass efficiency of the catalytic conversion unit is 94% and the volume efficiency is 86%.

Description The purpose of this study is to use process Petrosim software to accurately simulate the catalytic conversion unit of naphtha with continuous reduction according to real conditions and to investigate the relationships and effects of all operational variables on the quality and quantity of gasoline production, process optimization and finding The best values of operational variables have been taken to improve the appropriate process conditions and reduce operating costs and energy consumption,

43 so that in case of all kinds of problems and fluctuations in the control and process parameters ahead, appropriate action can be taken to produce 100 octane gasoline. Also, practical methods and shortcuts to control and maintain the optimal octane number of gasoline product in relation to changes in unit capacity and composition of feed percentage and catalyst coking, etc. should be provided. Another purpose of this research is to present the possible bottlenecks of the Isfahan refinery gasoline unit and to study its solutions. In general, catalytic conversion of naphtha is a refining process in which the heavy naphtha feed passes through the catalytic bed of several reactors at high temperature and pressure, the number of aromatic compounds in naphtha increases and eventually the octane number increases. The catalytic conversion process can be considered as a process with the following objectives: 1- Production of gasoline with high octane number, 2- Preparation of aromatics for petrochemical industries, 3- Production of hydrogen for industrial uses such as hydrocracking and desulfurization Naphtha feed is usually treated with hydrogen to remove impurities that prevent beneficial reactions or poison the reforming catalysts. The naphtha feed is either obtained directly from the crude oil distillation unit or is the result of reactions of petroleum products of other refining units such as the Isomax unit. In general, the catalyst used in this process is usually less than one tenth of the percentage of platinum metal in combination with another noble metal based on alumina. In the catalytic conversion process, platinum-rhenium heterogeneous metal catalysts based on aluminum oxide (Pt-Re/Al2O3) are commonly used. Heterogeneous metal catalysts are composed of two parts, the base and the metal. The metal is the active element of the catalyst and the base often plays the role of retaining the main metal. Most of the gas condensate, oil extracted from gas wells, is also composed of naphtha. This liquid fuel can also be extracted from coal tar. The chemical and petrochemical industries are the main buyers of naphtha, which is used as feedstock for various petrochemical products, including solvents and diluents, 44 plastic raw materials, synthetic fibers, and industrial alcohols. For example, most dye thinners are made of naphtha, and most ethylene plastic compounds are made with naphtha. Catalytic processes can also be used to convert naphtha to high-octane gasoline and other petroleum fuels. Naphtha is a very useful solvent with a variety of applications, so it is also used to make detergents and to refine other hydrocarbons. It is also used to produce polishes and varnishes and as a heating and cooking fuel (similar to gas and kerosene). Naphtha is precisely composed of hydrocarbons containing 5 to 12 carbon atoms with boiling points ranging from 30 to 200 °C. That is, if we heat the crude oil from 30 to 200 degrees Celsius and separate the boiled part, naphtha will be obtained. Usually, 15 to 30 percent of crude oil boils at this temperature, so the same amount of crude oil can be converted directly to naphtha. It should be noted, however, that this range interferes with gasoline and kerosene. But naphtha is available in two types of light naphtha (between 30 and 90 degrees Celsius with 5 and 6 carbon hydrocarbons) and heavy naphtha (between 90 and 200 °C with 6 to 12 carbon hydrocarbons). The root of the word naphtha comes from the Persian word for oil, which has been introduced into European languages through Greek and Latin. The word oil has long been used to refer to light oils that could be extracted from the ground in the Baku region and other parts of Iran, and the same word entered Europe through Greek and Roman writers. The feed of the catalytic conversion process is usually heavy naphtha, which consists of four hydrocarbon groups: ➢ Paraffin, ➢ Olefin, ➢ Naphthene and ➢ Aromatic (PONA).

Introduction of Various Types of Naphtha Catalytic Conversion Units Gasoline production units related to the naphtha catalytic conversion process are divided into the following three models based on catalyst reduction methods: 1- Fixed bed catalytic conversion unit, 45

2- Catalytic conversion unit with periodic reduction, 3- Catalytic conversion unit with continuous reduction (moving bed)

Fixed Bed Catalytic Conversion Unit The process of this unit is performed in three or four fixed bed reactors under adiabatic conditions and high pressure with return hydrogen gas. During the working period of the catalyst, the inlet temperature to the reactor bed is raised to prevent the octane number of the output product from dropping due to reduced catalyst activity. The refined feed from the naphtha hydrogen treatment plant, while combining with the return hydrogen gas, after passing through a heat exchanger and heat exchange with the output product of the reactors and passing through a furnace, is preheated and enters the reactors in series. Because most reforming reactions are superheated, a furnace is installed before each reactor to bring the fluid temperature to the desired inlet feed temperature. The output current from the last reactor enters a pressurized separating vessel and the exhaust gas flow from the top is divided into two parts, one hydrogen product and the other return hydrogen gas flow and the liquid product at the bottom of the container to separate light gases and stabilize the reformate product the final passes through a stabilizing section. The duration of this period is affected by determining factors such as reduced reformat efficiency and reduced hydrogen production and the minimum allowable stop time of the unit.

Catalytic Conversion Unit with Periodic Reduction This type of reformer unit includes 4 to 5 fixed bed reactors. The naphtha reforming operation in this process lasts longer than the first type of fixed bed process. The main difference between this type and the previous reformer is the presence of an additional reactor called a swing reactor and a special connection system that allows the catalyst in each reactor to be regenerated while the rest of the catalysts in the other reactors are reacting with the feed. Has provided.

The advantage of this design is that the reforming operation is performed at a lower pressure, which creates compounds with higher carbon content in the reformat product as well as producing more hydrogen and consequently producing a gasoline product with a higher-octane number compared to the previous fixed bed method. More coke is produced mainly due to the higher average temperature of the catalyst bed of the last reactor. Therefore, the last reactor in this type of process is regenerated more times than other reactors.

Catalytic Conversion Unit with Continuous Reduction (Moving Bed) This process takes place in moving substrates at low hydrogen pressure and the feed stream enters the reactors radially. The catalyst moves between the reactor beds. In this process, the catalyst catches coke very quickly, which along with the reaction, the catalyst moves to the bottom of the reactor bed and after leaving the reactor, it is continuously recovered and regenerated and returns to the reactor from above. In this process, due to the mobility of the catalyst bed, it is possible to add or subtract catalyst from the bed. The spent catalysts are directed to a reduction tower, where the coke on the surface of the catalyst is burned and the catalyst is recycled. The reduced catalyst is returned to the top of the reactor and in contact with the naphtha feed inside the reactor, which is mixed with the return hydrogen gas and exchanged heat and preheated using a transducer with the output current from the reactor. This type of process also includes 3 to 4 reactors in series with a furnace installed before each reactor. Due to the fact that in this design, the possibility of continuous and continuous recovery of the catalyst is provided, so the formation and penetration of high coke on the surface of the catalyst is prevented and the unit operation is "performed" at low pressure. Also, in this type of process, the drop in reformat product efficiency or the reduction of hydrogen product production is minimized by choosing the right amount of catalyst circulation flow.

Description of the Process of the Units of Isfahan Oil Refinery, (EORC), Gasoline Complex The project of Isfahan Refinery Gasoline Complex has been constructed on a land with an area of 6.4 hectares located in the northeastern side of this refinery consisting of the following three process units: 1- Operation unit of naphtha hydrogen treatment, 2- Continuous reduction catalytic conversion operation unit (Octanizer) 3- Operational unit of increasing isomeric octane number In the naphtha hydrogen treatment plant, impurities such as sulfur and nitrogen that cause catalyst poisoning in the downstream catalytic units are removed from the impure naphtha. This process is carried out by passing crude naphtha through a catalytic substrate in an adiabatic reactor using hydrogen gas. In a continuous reduction catalytic conversion unit, with the gentle passage of heavy naphtha through the catalytic bed, three adiabatic reactors using hydrogen cause a catalytic reaction at high temperature and low pressure and a layer of coke forms on the catalytic bed. Therefore, in this unit, the catalyst is continuously reduced and recovered. The main product of this unit is gasoline with 100 octane number and its by-product is liquefied petroleum gas. With the launch of this project, Isfahan Refinery will be practically self-sufficient in importing octane boosters. In the isomerization unit, the light naphtha feed is desulfurized and dehumidified to dry the water in the feed. The isomerization process is then performed in a reactor adjacent to dehydrated hydrogen. The product of this gasoline unit is 88 octane and its production capacity is 27,000 barrels per day.

Isfahan Refinery Complex Naphtha Hydrogen Purification Unit The purpose of the naphtha hydrogen treatment plant is to produce clean and refined feed to feed the octanizer and isomerization units. The feed of these units should have the least number of contaminants such as sulfur, nitrogen, water, halogens, olefins, arsenic, mercury and other metals, so as to affect the efficiency of downstream units, especially the catalyst of these units. 48

The feed of naphtha hydrogen purification unit can be HSRG produced by upstream units (distillation units) or a mixture of HSRG and naphtha produced by decomposition units or naphtha produced by Isomax units. All of these sections can have different levels of the above-mentioned contaminants, which are detrimental to catalytic conversion reforming catalysts and isomerization, and therefore hydrogen treatment operations are essential. This process is licensed by Exxon France. The naphtha purification process takes place in an adiabatic reactor in the presence of a nickel-molybdenum bimetallic catalyst in the presence of hydrogen. A relatively high temperature (about 300 °C) is required for the process to perform the desired reactions. After chemical reactions, naphtha is stripped to remove light hydrocarbon compounds and gaseous compounds (including hydrogen sulfide

H2S and water). After stripping, the oil section obtained in the separator tower is divided into two specific sections for feeding the isomerization unit (light naphtha) and the octaneizer unit (heavy naphtha). The high efficiency of octanizer and isomerization units depends a lot on the efficiency and effectiveness of the naphtha treatment unit. The maximum permissible level of sulfur and nitrogen contaminants in the treated feed is 0.5 pm octanizer. Also, the maximum limit of pollutants such as lead, copper, silica, nickel, chromium is 5 ppb.

Conclusion The purpose of this study is to show the effects of unit capacity on two important and basic parameters of the catalytic conversion process and to determine the importance and necessity of adjusting process conditions and appropriate operating variables for each capacity to stabilize the octane number of 100. The main result of this research is that with increasing the capacity of the catalytic conversion unit, the octane number of the gasoline product decreases and in contrast, the percentage of coke formed on the surface of the unit catalyst increases. Of course, in these changes in unit capacity, the percentage of coke formed is within the allowable range.

Figures and Tables

Figure 1. Cyclic Regenerative Unit diagram (Cyclic Regenerative Unit)

Figure 2. Simulation of a Three-Phase Feed Separator Container for Emptying the Naphtha Hydrogen Treatment Plant

Acquiring the title of leading company and first rank among

the top 500 companies in Iran (IMI-100), 2014

Research and Development / Summary of Implemented Student Projects

Title Optimizing the performance of heat exchangers of Isomax unit of Isfahan Oil Refining Company using pinch technology

Information Master Degree in Chemical Engineering

Abstract Today, energy is recognized as one of the main factors for the formation and development of industrial societies. Thus, the level of access of countries to various energy sources indicates their progress and political-economic power. The high price of energy and the enormous costs of its capital sector, on the one hand, and the reckless growth of industrialized societies and their growing need for energy, on the other hand, have led countries to avoid wasteful consumption. Energy efficiency as well as reducing production costs and increasing public welfare, implement policies under the title of optimizing energy consumption. Due to the increasing consumption of energy resources and rising fuel prices and the fact that the main costs of industrial and operational units, including refineries, which supply the main energy sources of the country and fuel needed by various industries, including defense industries, are spent on energy supply of these units. On the other hand, the limited energy resources indicate the need for study, calculation, engineering analysis and the application of necessary measures to reduce the needs of these units. One of the ways to reduce energy consumption is to recycle

52 the energy lost in process systems, which depends on the temperature of the fluids and economic issues. In this regard, various methods for reusing the energy that is normally wasted have been proposed in factories, which are known as thermal recycling. These activities have so far led to the invention of several methods in design, which generally fall into three categories: 1- Experimental methods, 2- Mathematical methods and 3- Thermodynamic methods (pinch method) The experimental method is based on the application of experimental rules and during several evolutionary stages, suggests a suitable arrangement for the network. For example, it is recommended that if possible, the hottest hot stream in the process, exchange its energy with a cold stream whose final temperature is higher than other cold streams. This method, despite its simplicity, is not reliable and does not offer the best design in a complex chemical unit. The mathematical method is the oldest method, which first defines all possible arrangements for the network of heat exchangers, then evaluates the unit efficiency for each arrangement by complex, time-consuming mathematical calculations, and gradually removes inappropriate options until the final selected network is determined. In this method, the number of different options and scenarios in solving each problem will be very high, and in a problem such as the heat exchangers network of a refinery, the number will reach more than 10 cases. Therefore, evaluating this set requires a large computer and a lot of time. Therefore, the application of this method in an industrial unit with the dimensions and complexity of a refinery will be limited. The thermodynamic method (pinch), while not having the unnecessary complexity of the second method, is also reliable and has made great strides so far. Using this method and before the final design, design engineers can calculate the minimum heating and cooling required for the process, the minimum level required for heat exchange, and costs, and have a correct view of the final optimal network. 53

In addition, unlike the second method, due to the simplicity and ease of use, the design control is in the hands of the design engineer and he can make decisions in different stages and make the necessary selection. This method does not rely on experience or error testing, and it makes network design easier and takes less time. In the early 1980s, as a new wave of energy crises began, pinch technology emerged as a tool for designing heat exchanger networks. Process heat integration (pinch technology) is one of the most useful ways to analyze and manage energy consumption, the first goal of which is economic savings through the integration of energy consumption.

Description One of the industrial complexes in which the network of heat exchangers is widely used is the oil refinery, which has always been one of the defined projects for the design of these networks. Carefully in the designs made in the existing units of the country's oil refineries, it can be seen that the heat exchanger networks in many of these units have been designed without regard to the principles of thermal integration and need to be reviewed. Therefore, thermal integration studies in these units seem necessary. What has been evaluated in this project based on this need is the thermal integration of the heat exchangers network in the ISOMAX unit of Isfahan Refinery so that as a result of reviewing this network, appropriate corrections can be made in it and an optimal design for it - as Research goal - to be achieved.

How to Expand Pinch Analysis in the Industry Simultaneously with the development of pinch analysis techniques, ICI faced a challenge in the crude oil distillation unit of one of the oil refineries, and that was how to provide additional energy to increase production capacity in this unit by 20%. The solution seemed to be to add a furnace to the unit to supply this extra amount of energy, but this solution was not only costly but also faced with a lack of adequate and safe space to place the furnace in the unit.

Therefore, process integration teams were called in to find a solution to this problem. In a short period of time, using a targeting strategy, they realized that this unit needs less energy than the current amount, even though the production capacity is increased. In this way, these teams quickly need less than the current amount of energy to build their designs. In this way, these teams can quickly reduce their plans to generate energy supply costs and avoid installing the furnace and paying for its investment in the unit. Following this, ICI expanded the use of pinch analysis throughout the company by defining new projects in a wide range of chemical processes. New research findings were rapidly applied in industrial processes and developed greatly with the emergence of new challenges in industrial units. In addition to ICI, companies such as Union Carbide and BASF have reported efficiency in applying pinch analysis techniques to their projects.

Progress in the Design of Heat Exchangers Network With the advent of heat pins in the late 1970s, increasing efforts were made in academic and industrial settings to develop and apply systematic methods in the design of heat exchanger networks. The design criterion in most of the initial methods was to minimize the level of heat transfer in the network and based on this, heat transfer units were selected, but due to rising energy prices, development of targeting strategy and discovery of heat pinch, standard design methods in the late decade. The '70s and early' 80s led to maximizing energy recovery in the grid. Heat pinch was discovered as the most important concept in the design of an independent heat exchanger network. Of course, some people Provided a basic understanding of thermal pinch. They linked the additional utility consumption to the heat flow through the pinch, thus creating the concept of proper placement of process equipment relative to the pinch. Pinch analysis was initially used for new designs of heat exchanger networks. In 1995, Van Reisen and colleagues presented a path analysis perspective on network revision to evaluate the independent parts of an existing network to find the most economical and practical energy storage 55 opportunities. These were independent sections of paths called Utility Paths in which the designer could pursue a reduction in utility consumption. The concept of network pinch was first highlighted by Asante and Zhu in 1996 and 1997 as a constraint to increase energy recovery on utility paths.

The Concept of Process Integration Process integration describes how heat is recycled, and in short, process integration is the creation of systematic and general models for the integrated design of production systems, integral processes throughout the unit with emphasis on the efficient use of energy and the reduction of environmental impacts.

View Process Integration Applications Although the above section emphasizes energy and the environment, process integration methods are used for a variety of topics. Reasons for using process integration in units and design are: ➢ Reduce annual costs by identifying the trade-off between operating costs (raw materials and energy) and investment costs (equipment). The cost of equipment. ➢ Increase production volume (unit capacity) and use process integration to eliminate operational bottlenecks. ➢ Reduce process problems (start and stop unit) ➢ Increase process controllability (it is an internal tool and is different from process control) by modifying the arrangement of unit components (topology) and equipment parameters to simplify control regardless of the actual control of the system. ➢ Ensuring the flexibility of the system by observing the unit specifications (raw materials or new products, compatibility of production volume, etc.) and preventing unwanted or reducing them (such as scaling of heat exchangers or deactivation of catalysts) against changing operating conditions, by selecting Suitable for unit layout and equipment specifications. 56

➢ Reducing unwanted items such as reducing unit emissions, reducing fossil fuel consumption, the possibility of using secondary sources of energy production.

Design with Pinch Approach Process integration using pinch technology offers a new approach to targeting to determine the lowest energy consumption before designing a heat recovery network, taking into account the limitations of vitiligo heat recovery systems in the design of the process core. they take. In this approach, the interplay of heat recovery and utility systems is also examined. Pinch design can provide opportunities to correct the process core to improve and integrate process energy consumption. The integration approach in the Pinch approach is unique because it considers all processes with multiple flows as one integrated system. For a given amount of heat transfer (Q), the level required for heat transfer increases. As heat recovery ∆Tmin increases in the converter, energy demand from external sources increases. Therefore, setting a value affects both the investment cost and the energy cost required.

Objectives in Optimizing the Network of Heat Exchangers Heat exchange network optimization has created a huge change in the structure of heat exchangers. Choosing the appropriate optimization method responds to the issues raised in this field: ➢ The amount of energy storage with the minimum cost of equipment. ➢ The possibility of increasing the amount of product without using excess energy. ➢ Determining the best places to improve the existing heat exchanger network. ➢ Determining the need of the heat exchangers network to use new heat exchangers and the possibility of changing the currents passing through the heat exchangers. Isomax (hydrocracking) unit is one of the most important refining units in oil refineries. The task of this unit is to convert heavy cuts into lighter and more valuable 57 cuts, so that in this unit the process of breaking heavy molecules in the presence of hydrogen gas and It is performed on the catalyst bed (at high temperature and pressure). This unit uses a number of heat exchangers and is one of the most consuming units of refinery energy. In this unit, there are currents that need to be warmed and there are other currents that need to be reduced. By combining these currents and exchanging energy between them, the needs of both for heating or cooling can be met, thus reducing the use of external resources needed for heating and cooling. Therefore, in terms of energy saving and recycling, with the optimal design of the heat exchanger network, at an optimal and economical level, the heating of cold streams by the energy available in hot streams can be done in the best way and to the extent Reduces the demand for energy supplied by external cooling and heating sources.

Process Flow in the Separation Section The inlet stream to the separation section contains various compounds from hydrogen and hydrogen sulfide to heavy hydrocarbon compounds, which in the separation operation are converted into products such as light gases, liquefied petroleum gas, light gasoline, heavy gasoline, kerosene and diesel.

Sponge Absorber The exhaust fluid, which is a mixture of all the products produced by the unit, is heated by passing through the heat exchanger shell to a temperature of 233 °C and entering the feed flash drum its light gases from heavy liquids are separated. Light gaseous hydrocarbons from this container are cooled by entering the air conditioner and enter the foam absorber container from below. Diesel, which is one of the final products, enters from the separation tower as Lean oil from above and, due to contact with light hydrocarbon flow, absorbs its heavy hydrocarbons and returns to Rich oil. Separation tower returns. From above, light gases are sent to the amine gas purification unit. 58

Separation Tower This tower has 40 trays. The end fluid flow is sent to furnace by pump. However, before entering it, it is mixed with the over flash current sent by pump from the separation tower. The output current from furnace enters tray 5 in the separation tower. The upstream of the tower series is cooled and liquefied in the air conditioner and enters the collecting vessel. Part of a liquid flow out of this vessel by the pump is injected as a reflux to the top of the separation tower. The exhaust gas from collector in condenser is cooled and liquefied and enters collector. The exhaust gas from this container is compressed by the sour gas compressor and sent to the gasoline stabilization tower. Also, the sour water leaving the container by the pump is sent to the sour water treatment plant, the product of heavy naphtha is obtained in the separation tower and enters the stripper tower. This product is released by the reboiler and is returned to the separation tower from the top of the tower. The current containing this product is pumped from the bottom of the tower to the condenser by the pump and then the passage will be sent to the reservoir. The kerosene product (Kerosene) is obtained from tray 23 in the separation tower and enters the Nia the instrument becomes. Its light hydrocarbons are released by the reboiler and return to the separation tower from the top of the tower. The carrier current of this product is sent from the end of tower to pump by air pump and then to the tank by passing through condenser. Diesel is obtained from tray 15 in the separation tower and enters the stripping tower. Its light hydrocarbons are released by direct injection of low-pressure water vapor and returned to the separation tower. The carrier current of this product is divided from the end of tower using pump to air conditioner and then by passing through condenser to two currents; One current is injected as lean oil and the other current is sent to the tank. The current taken from Tray 6 in the Separation Tower is sent to Furnace after passing through the Reboiler. At the bottom of the separation tower -under the tray 1- Low pressure water vapor is injected to separate light materials from the tower residue and the separation of the 59 separation tower is sent as a recycled feed (Recycle Feed) to the beginning of the unit.

Gasoline Stabilization Tower The feed of this tower enters the tower from the collecting vessel by pump through the heat exchanger shell in tray 16. The top series gases of this tower enter the top container of series through the condenser and the exhaust gases from this container, which contain butane and light gases, are sent to the gas purification unit with amine. The flow of hydrocarbon liquid out of this container at the exit of pump is divided into two streams; One stream returns to the tower as a return stream and the other stream is sent to the LPG unit as a liquefied petroleum gas (L.P.G) product. The product of light gasoline or light naphtha (Light Naphtha) comes out of the end of the tower and cools after passing through the heat exchanger tube and condenser. At the bottom of the tower, the reboiler releases light gases with liquids at the bottom of the tower.

Conclusion In the proposed design for a single heat exchanger network, it has been proposed to add four heat exchangers to the network. These changes in the studied network reduce the utility consumption per unit by 4.8 MW, which has a good economic value considering the return-on-investment period of 14.5 months, but its implementation in practice needs to be investigated. What can be obtained from the review study of the heat exchanger network in this unit is the confirmation of what was mentioned in the introduction of the dissertation and it is the appropriate economic efficiency of most networks designed by the pinch method because in the design presented in this study as an economically optimal design, the pinch principle is fully observed. Creating utility paths by adding new heat exchangers as the method used in this project, by providing many design options, provided a suitable tool to evaluate the 60 economic efficiency of the proposed designs and finally, the optimal design among the options. It is true that the network design in this study was not a complex design, but it should also be noted that in this project, by creating utility paths, a convincing method was presented to prove the optimality of the proposed design; On the other hand, if the new pseudo-design perspective was used in the design, the optimality of the proposed design would remain unclear due to the lack of many design options.

Figures and Tables

Figure 1. Heat Transfer Equation

Figure 2. Enthalpy Temperature Relationship for Combining Hybrid Curves

Figure 3. Combined Curve

Acquiring the title of leading company and first rank among

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Research and Development / Summary of Implemented Student Projects

Title Combined analysis of pinch-exergy to optimize energy consumption in the distillation tower of Isfahan oil refinery

Information Master Degree in Chemical Engineering

Abstract In the present dissertation, the analysis of exergy analysis and the perspective of reversibility and its application in the distillation unit of Isfahan refinery to reduce energy consumption has been studied. The purpose of this dissertation is to analyze the exergy and target the distillation tower of Isfahan refinery and to determine the appropriate conditions to reduce the exergy loss of the column, in which different modes and suitable suggestions were presented. Parameters such as: change in the flow of side pumps, change in the arrangement of side pumps, change in the return temperature of the side pump, change in the pressure of the distillation tower, change in the amount of steam injected into the main tower and change in the process structure. No, has been studied to reduce the loss of exergy.

Description Distillation is the most widespread method of separation in the chemical process industry and about 95% of the separation in the chemical industry is done by distillation and about 3% of the total energy consumption in the world is consumed in distillation units. Therefore, the distillation unit is the first goal to improve the energy

63 efficiency of various processes. Consuming more energy leads to more economic and environmental costs. In the definition of energy, it is assumed that all states of energy are equal and the loss of energy quality is not calculated, but the analysis of exergy is based on the first and second laws of thermodynamics and thermodynamically shows the defects of the process, material loss and energy. In the energy balance, we apply the first law in a closed environment and the possibility of energy loss is not considered, exergy analysis must be used to be accurate in expressing irreversibility. The present dissertation examines the analysis of exergy and the perspective of reversibility and its application in the distillation unit of Isfahan refinery to reduce energy consumption. From the point of view of exergy analysis, the main purpose is to obtain the profile of exergy loss through the entropy balance of the column and it can be used to determine the possibilities of improvement in the distillation column. This profile can be obtained using the results of computer simulators. The main advantage of this view is that it considers the actual operating conditions of the column. The purpose of the reversible view is to determine the thermodynamic minimum of the column. Under these conditions, the column has an infinite balance tray and is fully reversible, in other words, no thermodynamic dissipation occurs in it. As we know, these conditions of action are not possible. Theoretically, to obtain the enthalpy temperature reversible profile, we must solve the mass balance and energy equations for all components simultaneously under the conditions in which the column operates in the reverse flow mini-wax. For two- component systems, due to the small size of the problem, the equations are relatively simple and the profile can be easily obtained. Many applications of the concept of exergy, based on exergy techniques, can be used to reduce energy consumption in industries that reduce energy loss and process flexibility economically and environmentally. Exergy analysis can provide a lot of information about the performance of industrial units and their modification and optimization. The first unit in crude oil refineries is the distillation unit. The driving force of the distillation operation is the difference in temperature and the difference in 64 the boiling point of the compounds. Crude oil is a combination of hydrocarbons that are generally single molecular weight and isomeric, so the separation range of crude oil distillation products is based on their boiling point. The design of the tower is usually based on thermal pairs. However, both modes shown produce the same products; in practice, crude oil distillation towers cannot be designed as shown in the figure. The first problem is that the welder requires a lot of heat at the bottom of the tower to obtain products with a high temperature range, and steam is usually not suitable for providing such a high temperature. Also, the higher temperature of the welders causes the decomposition of hydrocarbons as well as fouling and coking in the weld. The maximum allowable temperature in oil refining is usually around 300 °C. Therefore, in practice, a large amount of heat required by welders is provided by direct injection of steam, and this has two advantages: 1- Steam provides some of the heat required for distillation. 2- Steam provides less operating pressure for welding compounds, which increases volatility. Extrusion of steam by lateral currents in the work tower is difficult. In crude oil distillation towers, heat is generated by the liquid being removed by lateral flows and cooled and returned to the tower, which causes some of the steam to condense by direct contact with the cold liquid in the tower. However, this reduces the efficiency of the tower because cold liquids are not efficient in the distillation process, but must reach saturated liquid conditions. All materials that come out of the tower as a product must evaporate on top of the feed tray. In addition, some steam must be generated in addition to the current intensity to return to the tower as condensate after condensing from the top of the tower. This extra evaporation to create the return liquid is called over flash. For residual separation, we need more temperature, there are valuable materials in the bottom of the atmospheric distillation towers that can be separated. Therefore, the rest of the atmospheric distillation towers are reheated to a temperature of 400 °C or higher and then fed to the second tower, called the vacuum tower, which operates at 65 very low pressure to further separate the compounds. Designing vacuum distillation towers is easier than designing atmospheric distillation towers mainly because they have only two lateral flows and one residual vacuum outlet.

Conclusion The correct choice of thermodynamic equations to predict thermophysical properties plays an essential role in the accuracy of the simulation. In choosing thermodynamic equations, all conditions must be considered. Temperature and pressure range, type of compounds and type of materials in solution, polarity and non-polarity of materials are the most important parameters that must be considered. Thermodynamic equations must calculate the thermodynamic properties (fugacity coefficient, enthalpy, entropy, Gibbs free energy and volume) and the transfer properties (viscosity, thermal conductivity, diffusion coefficient and surface tension) of the system. Depending on the type of system and the type of simulation environment, whether ideal or non-ideal, type of process, gas or electrolyte and other parameters, different equations have been proposed by the software.

Table 1. Selection of appropriate thermodynamic equation Method Description BK10, CHAO-SEA, GRAYSON For low pressures in the range of several atmospheres (atmospheric tower and vacuum tower) CHAO-SEA, GRAYSON, PENG-ROB, For medium pressures up to several RK-SOAVE tens of atmospheres GRAYSON, PENG-ROB, RK-SOAVE For hydrogen rich processes, Hydro finer PENG-ROB, RK-SOAVE For oil units

Description of Crude Oil Input to the Distillation Unit The study of the properties of oil flows is one of the most complex cases in thermodynamics. Petroleum streams include various compounds such as metals, 66 sulfur, light gases, H2S and heavy hydrocarbons. The amount of each of these compounds depends on the oil fields from which these oil flows are derived. Most of these systems require large amounts of steam, and breaking their heavy compounds is a complex and costly process. In the chemical industry we deal with compounds (molar components). In crude oil refining, we are in contact with boiling point ranges. For example, if we heat a sample of crude oil in a container at atmospheric pressure, the temperature at which the first vapor particles form is called the initial boiling point. This corresponds to the bubble point of a mixture of certain chemical compounds. If we continue the heating process, more material will evaporate. The 5% point is the temperature at which 5% of the original sample is vaporized. The point is 95% of the temperature at which 95% of the volume of the sample liquid evaporates. There are three types of boiling point analysis: 1- ASTM D86 2- ASTM D158 3- True Boiling Point (TBP) The first and second cases are similar to those described earlier. In the third case, the vapor from the container passes through a filled distillation tower and a certain amount is returned. Thus, the third analysis shows the fractional separation, while the first and second cases are only a single-stage separation. ASTM analysis is easier and faster to perform. TBP analysis provides more accurate information about crude oil content. The TBP chart of crude oil gives an estimate of the amount of each oil cut in crude oil. These curves are obtained in the software with the help of Plot Wizard. The properties of an oil stream are not specified in the form of compounds, but instead properties such as 5% point, Reid vapor pressure, flash point and octane number are used. The method used for quantitative calculations of petroleum components is to break them into quasi-compounds, each with a boiling point, specific gravity, and medium molecular weight. Aspen Plus software creates these quasi-compounds by providing assay information about crude oil. Available data for 67 a crude oil sample include experimental data from the TBP curve, gravity curve, and light-end analysis. The term light-end refers to specific light hydrocarbons such as methane and ethane. API data provide different shear densities when produced in TBP distillation. Aspen Plus software has a wide range of properties of oil flows in various fields in the Oil Library. Considering that in the definition of crude oil, the information related to light end cutting determines the light compounds present in the crude oil and for the rest of the crude oil, the information is available in the form of TBP curve, so in the definition of input feed, the compounds must, the properties of light end should be specified and the properties of crude oil should be defined as assay in the software. To perform calculations on a mixture such as crude oil, which is continuous and uninterrupted in nature, the continuous mixture is divided into a number of hypothetical components (Pseudo Component) and thus simulation operations and distillation tower calculations similar to a multi-component distillation algorithm. They do. In Aspen software, first the TBP and density curves as a comprehensive equation from zero to one hundred percent crude oil are generalized, and then according to the number of hypothetical compounds desired by the user, the curve is divided into hypothetical components.

Figures and Tables

Table 2. Crude Oil TBP Curve Information in Terms of Distillation Percentage Frac. Boiling range of Frac Cumulative Cumulative No at 760 mmHg °C Wt% Vol% 1 IBP – 15 0/39 0/58 2 15 – 65 3/43 4/67 3 65 – 100 7/76 9/97 4 100 – 150 15/07 18/39 5 150 – 175 19/64 23/48 6 175 – 200 23/60 27/82 7 200 – 250 33/10 37/98 8 250 – 275 36/65 41/42 9 275 – 300 41/76 46/84 10 300 – 350 46/30 51/30 11 350 – 385 52/44 57/26 12 385 – 512 65/32 69/44 13 512 – 538 70/78 74/48 14 538 – 561 74/40 77/78 15 561 + 100/00 100/00

Table 3. Crude Oil Density Curve Information in Terms of Weight Percent Distillation Frac. Boiling range of Frac Mid. Point Mid. Point Sp. Gr No. at 760 mmHg °C Wt% Vol% 60°F. 60°F 1 IBP – 15 0/195 0/29 0/05761 2 15 – 65 1/910 2/625 0/6394 3 65 – 100 5/595 7/320 0/7019 4 100 – 150 11/415 14/180 0/7460 5 150 – 175 17/355 20/935 0/7719 6 175 – 200 21/620 25/650 0/7840 7 200 – 250 28/350 32/900 0/8039 8 250 – 275 34/775 39/700 0/8361 9 275 – 300 39/105 44/130 0/8425

10 300 – 350 44/030 49/070 0/8743 11 350 – 385 49/370 54/280 0/8862 12 385 – 512 58/880 63/350 0/9090 13 512 – 538 68/050 71/960 0/9312 14 538 – 561 72/590 76/130 0/6430 15 561 + 0/9904

Table 4. Information on the Weight Percentage of Light Crude Oil Compounds Component Fraction PROPA-01 0/2104 ISOBU-01 0/1945 N-BUT-01 0/3657 2-MET-01 0/1162 N-PEN-01 0/0658 2-MET-02 0/0086 3-MET-01 0/0035 N-HEX-01 0/005 2,2- D-01 0/002575 METHY-01 0/002575 2,4-D-01 0/002575 BENZE-01 0/002575

Figure 1. Change in Feed Input to the Atmospheric Distillation Tower 70

Block V102: Column Grand Composite Curve (T-H for Main Column)

350 325

Ideal Prof ile

300 Actual Prof ile

275

250

225

TemperatureC

200

175

150 125

-20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 Enthalpy Def icit MW Figure 2. Comprehensive Compositional Curve of the Atmospheric Distillation Tower in the Ground State

Block V102 (PetroFrac) Stream Results Vol.% Curves 1000

True boiling pt V102PV True boiling pt V105P 800 True boiling pt V106P True boiling pt V107P

True boiling pt V102PL

600

400

TEMPERATUREC

200 0

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 Volume percent

Figure 3. TBP Atmospheric Distillation Tower Products

First rank in "Petroleum Products Group" of Iran's top

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Research and Development / Summary of Implemented Student Projects

Title Simulation of Combustion Chamber of Furnace 151 Distillation Unit of Isfahan Refinery Using Computational Fluid Dynamics

Information Master Degree in Chemical Engineering

Abstract One of the low-cost ways to optimize process equipment in refineries is to simulate process equipment and find the optimal operational and structural conditions of the equipment. In this research, simulation of furnace 151 of Isfahan refinery has been performed using Fluent software. In this simulation, the standard k-ε method is used to model the turbulence flow, the non-premixed combustion model method is used to model the combustion, and the DO finite direction technique is used to model the radiation. In this research, the results of simulated turbulent combustion flow including changes in molar fraction of different species, speed, temperature, pressure and heat transfer coefficient in different parts of the furnace in four different sizes of furnace pipes have been investigated. In the first case, the pipes are modeled in their actual and current size, and in later cases, the size of the pipes is increased. The results show that with increasing the size of the pipes, the temperature of the process fluid leaving the furnace has increased. The simulation results show that if a bluff is used in combustion currents, there will be no need to use a stability pilot. The results of the study of the effect of the percentage of excess air on the efficiency of the furnace also show that the higher the

73 percentage of excess air, the higher the fuel consumption of the burners for a certain absorbed heat and increasing more than 20% of excess air reduces the efficiency of the furnace.

Description Today, designing equipment for the clean combustion process as well as combustion with higher efficiencies is one of the goals of researchers and designers of combustion systems. Methods of computational development and accurate modeling of combustion flow behavior can be used as an important tool. In accurate simulation of combustion flows, the combustion model plays an essential role, because in addition to determining the amount of combustion species and products, it also determines the rate of release of energy from the combination of fuel and oxidant. In general, the two main functions of combustion models are: ➢ Determination of chemical changes in materials participating in combustion ➢ Determine the rate at which these chemical changes occur and release energy ➢ There are 36 furnaces in Isfahan refinery, Three furnaces are located in the distillation unit which consists of two parts, atmospheric and vacuum. The crude oil entering the distillation unit enters the desalination plant after passing through the networks of heat exchangers and increasing the temperature from 30 oC to about 130 oC with a pressure of 300 psig and from there enters the drum flash through a transducer. The liquid leaving the flash drum enters the 101st furnace at a temperature of about 240 oC. After absorbing heat at a temperature of about 351 oC. Leaves the furnace and enters the atmospheric tower. The bottom of the atmospheric tower enters furnace 151 oC at a temperature of about 336 oC, exits the furnace at a temperature of about 426 oC and enters the vacuum tower. Crude oil enters the furnace in liquid phase and furnace output in two phases. Furnace is of horizontal type with two radiant combustion chambers and one displacement chamber. Its design heat capacity is 36046 kj/s and its practical heat capacity is 32761 kj/s.

The flow of hot gases takes place in the form of natural suction and enters the atmosphere through a chimney after passing through the displacement section. Furnace of Isfahan refinery consists of two parts: ➢ displacement and ➢ radiation. As can be seen, the feed enters the furnace displacement section through 8 paths and passes through this section in the opposite direction of the combustion gases and enters the two radiation chambers equally. The radiant tubes are installed horizontally along the side walls and ceiling in the combustion chamber and the displacement tubes are horizontally located between the two combustion chambers. Ignition takes place from the floor and vertically. In each radiation chamber, the flow arrangement is for the two feed paths as opposite flow and for the other two paths as parallel flow, and finally the feed leaves the middle part of the furnace through the 4 paths of each radiation chamber. Each combustion chamber in the furnace also contains 12 burners. The power of each burner is based on additional suction and design air in normal operating conditions and maximum furnace is 1937.1 kj/s and 2423.6 kj/s, respectively. The inlet feed to the furnace is 91.05 kg/s and the feed enters the furnace at a pressure of 11.5/13.5 bar and leaves the furnace at a pressure of 0.7-0.3 bar.

Furnace Modeling Fluent software has been used to model this problem. This software is based on the limited volume method. In this simulation, the standard k-ε method is used to model the turbulence flow, the non-premixed combustion model method is used to model the combustion, and the DO finite direction technique is used to model the radiation. In this research, SIMPEL algorithm has been used to relate pressure and velocity sentences. The governing equations of this model are based on two basic assumptions. The first is that the problem is considered permanent, and the second is that the problem is considered incompressible. With this assumption, the density gain 75 in the equations is negated by pressure changes, and only its gradient due to the temperature gradient and concentration of chemical species is considered. This is a logical assumption for low Mach numbers.

Conclusion Human civilization has always depended on the use of energy in all its fields such as industry, transportation, housing and trade. Due to the limited resources of fossil fuels and the increasing price of them, saving on the consumption of such fuels has become particularly important today, and increasing efforts are being made to save on the consumption of different types of energy in various industries around the world. Combustion is the most important thermal process for energy production. Combustion of fuels currently accounts for more than 90% of global energy demand. About 79% of the fuels used in combustion of fossil fuels include coal, natural gases and oil. Oil refineries, which are the main centers of energy products in the country, use about 1% of refined oil as fuel. Due to the antiquity of Isfahan Refinery and also due to the more accurate design of refinery equipment in recent times, it is necessary to update and optimize the equipment of this refinery. One of the low-cost ways to achieve this is to simulate process equipment and find the optimal operational and structural conditions of the equipment. Due to the increasing processing power of computers in recent times, CFD simulations have more accurate results and the simulations performed give results close to reality. In this research problem, assuming heat transfer with constant flux to process pipes, the temperature profile inside the pipes has been calculated. To do this, first determine the geometry of the furnace and the exact specifications of the equipment inside it, the most important of which are the burners and the arrangement of the pipes inside the furnace, and then its geometric model is created in Gambit software. By studying the governing relations of combustion-rotational-perturbation- radiative valves, the appropriate model has been selected and, in the end, the following results have been obtained:

➢ Number of Element-Skewness diagram and Number of Element- Ortogonal quality diagram to evaluate the efficiency of the meshes used in furnaces and pipes show the desired quality of the meshes used in solving this problem. ➢ The models used to predict the changes in the molar fraction of carbon monoxide and carbon dioxide show an increase in these compounds with increasing height in the furnace, which can be attributed to the development of combustion reactions. ➢ Examination of diagrams of furnace temperature changes shows that from the beginning of the entry of air and fuel streams through the primary nozzles, combustion takes place inside the furnace and the rise in temperature along the inlet flows into the combustion chamber also indicates the progress of combustion reactions. ➢ Examination of the velocity profile diagram throughout the furnace shows that in the lower areas of the furnace, small areas with very low speed are observed, which can be attributed to the type of natural suction used in furnace 151 of Isfahan refinery. After these areas, there are areas related to the burners, which due to the type of combustion flow regime, which is a turbulent flow, the rate of change of velocity profile in these areas is very high and the highest amount of turbulence in the furnace is related to these areas. By moving away from the center of the burners as well as increasing the height, the amount of turbulence gradually decreases and the velocity of the combustion gases reaches an almost constant rate. ➢ Examining parameters such as temperature, pressure, velocity and heat transfer coefficient with real mode with three modeled modes if the pipe diameter has increased shows that with increasing pipe size, temperature and fluid heat transfer coefficient increase and pressure decreases.

➢ The use of wind-bluff creates a return zone near the inlet streams and increases the amount of fuel-air mixing as well as flame stability. If the bluff-wind is used in the combustion currents, there is no need to use the stability pilot and as a result, there will be no interference between the pre-mixing pilot and the flame that occurs in the blow- burner accompanying burners. ➢ Graph of changes in efficiency in terms of percentage of excess air shows that increasing excess air up to 20% has improved combustion and increased furnace efficiency and increasing more than 20% of excess air has reduced furnace efficiency.

Figures and Tables

Figure 1. General Outline of the Furnace under Study and How the Pipes are Placed

Figure 2. Grid Used in Furnace Modeling

Figure 3. Changes in the Temperature of the Fluid Inside the Pipe in All Stages of Passing Through the Furnace

Figure 4. Fluid Phase Changes Inside the Pipe at All Stages of the Furnace Passage

Figure 5. Process Fluid Velocity Changes in All Pipe Passages in the Furnace

Figure 6. Pressure Changes in Different Areas of the Pipes in the Furnace

Figure 7. Changes in Heat Transfer Coefficient in Different Areas of the Pipes in the Furnace

Figure 8. Nusselt Changes in Different Areas of the Pipes in the Furnace

Figure 9. Temperature Changes in Different Areas of the Pipes in the Furnace

The first rank of the National Productivity Festival in the group of petroleum products during the years 2007-2011

Research and Development / Summary of Implemented Student Projects

Title Mathematical modeling and simulation of the distribution of exhaust pollutants from Isfahan refinery

Information Master Degree in Chemical Engineering

Abstract In this research, with the help of computational fluid dynamics technique, simultaneous solution of partial mass retention equations, total and energy distribution of gaseous pollutants leaving the chimneys of Isfahan refinery were modeled. In modeling with the aim of increasing the accuracy of the results and investigating the effectiveness of the model from the selected turbulence model, three types of turbulence models including RNG. k-ε, Standard k-ε and Realizable k-ε are examined and compared and the RNG model. K-ε was selected as the final turbulence model to continue the study. Based on this, surface roughness was obtained for the developed model in the range of 2 to 2.5 meters. The sensitivity of the responses and the effectiveness of the model results in predicting the concentration of contaminants were calculated from the number of computational cells and 1.3 million computational cells were obtained as an acceptable threshold. Experimental design technique was used to investigate the effect of surface roughness and type of turbulence model on the model results and also to reduce calculation time and costs.

In order to investigate the accuracy of the model in local prediction of pollutant concentrations, the model results regarding carbon dioxide dispersion were compared with the results of field measurements within and within the boundaries of the refinery, which indicates acceptable accuracy and sufficient model predictions. All results were in the range of Fac2 and the model error was estimated in the range of 0.07 to 11.43% with an average of 6.34%. The results of this study show that according to the current emission characteristics of the chimneys of this refinery, up to a height of 20 meters above the ground, there is no pollution point with a concentration higher than the standard for major air pollutants. However, in some small points or areas, especially around production sources and at higher altitudes, pollution beyond the allowable limit is predicted by the model.

Description The word pollution is derived from the word pollutes meaning unclean and dirty. Air pollution is commonly referred to as atmospheric conditions in which substances are present in concentrations above normal in the atmosphere and affect humans, plants and substances. This definition includes all dangerous and harmless substances, solid, liquid or gaseous, natural and artificial, but most attention is paid to substances that have unpleasant effects such as bad breath, burning sensation, death or disease of humans, growth retardation or Destruction of plants, loss of materials or their properties, causes blurring or reduced vision and climate change. These unpleasant effects may be due to the high concentration of contaminants in the short term or the long-term effect of low concentrations of contaminants. The joint association of air pollution engineers and its control has defined the following definition of air pollution: Air pollution means the presence of one or more pollutants such as dust, fog, gas, mist, smoke, steam, particles, droplets, volatile ash and smog In the open air, with committees, characteristics and schedules that are dangerous to humans, plants, animals, and harmful to property, or unacceptably disrupt the easy use of life and property

Modeling the Distribution of Pollutants Produced in Isfahan Refinery using Gaussian Method In this study, the distribution of pollutants produced in Isfahan refinery was modeled using the famous and widely used Gaussian method to evaluate the efficiency of traditional models in some specific conditions. The Gaussian model is a basic model for predicting the concentration distribution of pollutants from a stable source under stable conditions. The most important assumption of the model is that the mean time-concentration profiles at any distance in the vertical direction from the source are gaussian distributions. It should be noted that this modeling was performed using the boundary conditions of the system to compare the results with experimental data. The general trend is that the Gaussian equation for CO2 emissions from each chimney is solved separately and the sum of the results of solving this equation for all chimneys at the sampling points was compared with the experimental data obtained at the same points. All these steps were performed by Excel software. Then, using the achievement of this step, the Gaussian equation for CO, NO2 and SO2 pollutants was solved and the results were compared with the results of the present model. For a source of continuous points (chimneys) with height located at the origin of the coordinate on which the wind blows in the dominant direction (+X) at a medium speed, the most general form of the Gaussian equation considering the reflection from the ground is as follows.

Qyz Hz−− H222 −− +()() q( x , y , z )expexpexp=+ 2u   222222 yz yzz

In this regard, q is the concentration of air pollutant in mass per unit volume (grams per cubic meter). Quantity Q is the rate of pollutant release per unit time

 y (grams per second), u wind speed at chimney height, standard deviation of

 concentration distribution in horizontal direction and z the standard deviation of the concentration distribution is in the vertical direction. H is the effective height of the central line of the flue, which is equal to the sum of the flue height and the rise of the flue (H = hs + Δh). Δh represents the ascent of the flue mass due to the buoyancy and momentum output of the chimney. This relationship estimates the concentration of receptors located at specific x, y, and z above the earth's surface. The value of parameter Q for each chimney is obtained by multiplying the percentage of pollutant mass in the chimney outlet (XCO2) by the total discharge output of the chimney.  Experimental parameters y and in the Gaussian model strongly affect the smoke mass distribution. In the beginning, these experimental parameters were calculated from experiments because these parameters depend on many factors such as atmospheric stability, wind speed, distance from the source and chimney height. In this study, these committees were calculated classification. According to table and weather conditions prevailing in Isfahan refinery on sampling days, including wind speed less than 2 meters per second (0.1 meters per second) and strong sunlight, the type of atmospheric stability was determined from category A (unstable). According to these conditions, and the experimental parameters and the relationships related to the site were recalculated, which are:  =+0.22(10.0001)xx−0.5 y  = 0.20x z The x parameter is the distance from the source of the contaminant. ASME relationship was used to calculate the smoke mass ascent in this study. This relationship is equal to:

1/3 dh= 7.4 F . h 2 ( s ) F in this relation represents the buoyancy force (m4/s3) and hs represents the height of the chimney. The buoyancy force is obtained by the following equation:

2 g FwRTT=−0000 ( pa) T p0

In this regard, w0 is the velocity of the chimney (m/s), R0 is the internal radius of the chimney, Tp0 is the temperature of the flue gas and Ta0 is the ambient air temperature. The quantity w0 is calculated from the following equation for each chimney. w Q= A / ( . ) 000

Using the relationships, the values of Δh and H quantities for each chimney were calculated. In the next step, the location of the measuring points should be determined in the coordinate axis of each chimney. For this purpose, a coordinate axis was defined for each chimney so that each chimney was located in its center, then the measuring points in the new coordinate axis were defined using the sublocation relation.

xxxyy =−+−()cos()sin00

yyyxx =−+−()cos()sin  00

In relation (x0, y0) the coordinates of the location of the chimney in the axis of primary coordinates (origin of secondary coordinates), α is the angle of wind with respect to the horizon, (x, y) and ) xy, ( are the coordinates of the measuring points in the axis of primary and secondary coordinates, respectively. Finally, by placing the obtained parameters in relation to the concentration of pollutants from each chimney in the sampling places and from the total of them with 3 the concentration of carbon dioxide in the air (q0 = 0.5237 g/m ), the concentration of pollutants in the environment was obtained and Their results were compared with experimental data. Finally, in order to better compare the results of these two models for other pollutants (CO, NO2 and SO2) were also examined. At this stage, the prevailing boundary conditions on the day of sampling were used and the concentrations of these pollutants in the sampling sites were compared.

Modeling the Distribution of Pollutants in Isfahan Refinery using the Solution of Survival Equations (Developed Model) Model equations include mass survival equations, momentum, turbulence committee survival equations, partial mass survival, and energy.

Total Mass Survival Equation (Continuity) This equation for slow flow is written as follows:  +=.( ) Sm t

In the relation Sm, it represents the source of mass production. If we simplify the equation from the equation of mean time using Reynolds's laws, we will have:

 +=div(u ) Sm t

Momentum Survival Equation These equations for laminar flow in general are:  () + =..( −) + ++pgF ( ) t

In relation P are static pressure,  ، stress tensor, F and  g external and gravitational volumetric forces. The stress tensor is calculated as follows.

T 2 = (   +  ) − . I 3 In this regard, μ molecular viscosity, I unit tensor and the second term of the relationship indicate the effect of increasing volume. It is better to use the momentum equation form to quantify the moment of velocity to obtain the momentum equation.

(u ) P +div( uu ) = − + div( grad. u ) tx

If each of the vectors is represented as the sum of the mean and oscillation values and the mean time equation is taken from both sides, the following equation is obtained using Reynolds's laws, regardless of the density fluctuations:

 u2    (uu) vu w P ( ) ( ) ( ) +=divudivgrad −++ −−−+u uS . txxyz ( ) ( ) x  

The terms in parentheses are called Reynolds stresses. The above equations are called RANS equations. These equations are explicit and no hypotheses have been used to simplify them. In addition, these equations do not form a closed device, ie the number of unknowns is more than the equations. One way to solve these equations is to calculate Reynolds stresses. These stresses are much larger than the viscosity stresses in turbulent flow, except in the viscous areas near the wall. Reynolds stresses consist of three vertical stresses and three shear stresses, which are equal in pairs and are shown as tensors. The calculation of these stresses at different points in the flow is the goal of all perturbation models

Presenting the Results of the Gaussian Model In this section, the results of modeling the distribution of pollutant gases from the chimneys of Isfahan refinery using the Gaussian model are presented. Observing the results, it can be said that the results of the present model are better than the Gaussian model and are much closer to the experimental results. The introduced statistical committees were also used to ensure more reliability and better study of the model results. These committees were calculated and compared for the results of both models. The results showed that the values of all 6 statistical quantities calculated for the present model are better than the Gaussian model.

Conclusion In view of the foregoing, the following can be expressed as final conclusions: ➢ By conducting a preliminary study and comparison on the types of turbulence models as well as the structure of scattering models, the k-ε turbulence model was used to model the turbulent flow in the present model. ➢ If the standard ε-k model is chosen to model atmospheric flow, the roughness height of 2 m and the Schmidt number of 0.5 turbulence will give better results and less error. ➢ f ε-k. Realizable to be used to model turbulence flow. Roughness height of 2 meters gives better results and less error. ➢ If the model ε-k. RNG is selected to model atmospheric flow. Roughness height of 2.5 m gives better results and less error. ➢ Studies on the results of various k-ε turbulence models showed that the use of the RNG.k-ε model makes the model results more consistent with experimental data than other k-ε models. ➢ The results obtained from the comparison of the mentioned turbulence models show that it is possible to estimate the surface roughness height in the computational range between 2 to 2.5 meters. ➢ After implementing the model and comparing its results with the measured intermediate data and also using the statistical committees r, FB, MG, VG, RMSE and NMSE, the accuracy of the model results was found to be significantly acceptable. The values obtained for these committees are: 0.187, -0.058, 0.913, 1.006, 1.778 and 0.005, respectively. ➢ According to the presented results, it is clear that the model in all sampling points except point 4 calculates the amount of carbon dioxide concentration more than the measured value.

➢ The amount of computational error can be estimated between 11.43% to 0.71% with an average of 6.3%. ➢ In this study, Gaussian model was used to model the distribution of pollutant gases from the chimneys of Isfahan refinery and the results were compared with the results of the present model. As expected, the results of the present model are better than the Gaussian model and are much closer to the experimental results. Statistical committees r, FB, MG, VG, RMSE and NMSE were also used to provide more confidence and better study of the model results. These committees were calculated and compared for the results of both models. The results show that the values of all 6 statistical quantities calculated for the present model are better than the Gaussian model. ➢ To further ensure the meshing method and the number of computational cells obtained in one step, the number of meshes was reduced from 1.387 10 106 to 1.004 6 106 and the model was run several times for this number of meshes. The results of this step and its comparison with the results of finer networking showed that a reduction of 27.65% in the computational cells resulted in a reduction of at least 65% in accuracy. In this study, in order to investigate the effect of ambient temperature, the distribution of pollutants leaving the 501 chimneys separately in the range of 44234 computational cells was investigated. Exhaust from this gas chimney with an intensity of 1.797 kg per second at a temperature of 330 °C. The results show that a 44 degree increase in ambient temperature caused a very small increase in the maximum concentration of calculated pollutants in the entire computational range. These maximum concentrations are observed right on the chimney. Changes in the concentration of pollutants

are so small that the effect of ambient temperature can be easily ignored. ➢ According to the results of the model for the conditions of the seasons, it can be said with confidence that at an altitude of less than 20 meters there is no unauthorized range for any pollutants and their danger does not threaten the staff and the environment of Isfahan refinery.

Figures and Tables

Figure 1. Cartesian Coordinate System used in the Gaussian Model (Colls, 2002)

Figure 2. Computational Range to Study the Effect of Ambient Temperature

Second rank of the top 100 companies in Iran's economy, 2011 The first rank of the top 100 companies in the Iranian economy, 2010

Research and Development / Summary of Implemented Student Projects

Title Analysis of crude oil and petroleum products of Isfahan refinery distillation unit with newer methods GC-DHA, XRF, HPLC, ICP and FTIR

Information Master Degree in Chemistry Analysis

Abstract In this research, instrumental methods have been used to measure important compounds and elements in the feed and products of the refining unit of a refinery in Isfahan. Knowing the exact amounts of these compounds and elements can play a constructive role in regulating the conditions of towers, converters, reactors and other equipment and operational parameters and to the refining engineering unit in achieving the goals of the complex that increase the quality and quantity of final products and applications. Instrumental methods used in this study include flame atomic absorption and emission, induced coupled plasma emission spectroscopy, X- ray and ultraviolet fluorescence, high performance gas and liquid chromatography and infrared spectroscopy. Metal ions including vanadium, nickel, lead, iron and sodium were measured by induction coupled plasma and flame atomic absorption or emission spectroscopy and the results were in the range of 36.2 to 72.8, 30, respectively. 0.0 to 21.7, less than 0.05 to 1.83, 0.25 to 14.52 and 0.20 to 7.95 mg / kg were obtained. Sulfur element was measured by X-ray fluorescence of wavelength scattering type and the results showed that the sulfur levels in the samples ranged from 189.2 to 27099 mg/kg.

Gas chromatography method was used in lighter sections of liquid, which included light and heavy gasoline, a mixture of naphtha and crocin, to analyze the composition of the constituent hydrocarbons. In light diesel cutting in atmospheric tower, heavy diesel from vacuum distillation tower and integrated gas oil product, single, double and multi-ring aromatic aromatics were measured by high performance liquid chromatography by values of 11.58 to 17.66, respectively 7.13 to 7.22 and 0.06 to 0.85 g per 100 ml were reported and it was found that these results are in the acceptable range. Finally, the possibility of using the infrared method to measure the octane number in gasoline and some intermediate products was investigated and it was found that the results of the method used are not reliable for products with variable texture and for intermediate products such as isomerization units and Catalytic converters are relatively consistent with the results of the standard octane engine method, but the same amount is not satisfactory for operating units.

Description In the design of Isfahan Refining Company, like any other refinery, the maximum concentration of metal elements in the complex feed is considered as an effective parameter. This means that these concentrations should not exceed the values considered in the design. Continuous monitoring is very important as the input feed may be supplied from different sources. These numbers may have changed slightly in recent years due to the stability of the feed, but now, due to changing sources of feed supply or crude oil entering the complex, they are constantly changing, and this has doubled the importance of monitoring. With the implementation of the refinery development plan and the creation of an atmospheric unit waste conversion unit and vacuum distillation, new specifications have been considered for crude oil and tower waste, which should also be considered. Various instrumental methods have been proposed to measure the number of metals in petroleum products. Some of these methods include equipment such as ICP, AES and AAS. The use of any of these equipment’s requires sample preparation. 95

Preparation is a very important step that can easily affect the quality of the analysis. The use of chemicals in the sample preparation process can cause the entry of similar analyte species or interfere with the measurement. Heating the sample can cause some of the analyte to be lost. At this stage, the concentration or dilution can be done during preparation. The two preparation methods used in this study are acid digestion and sample emulsification.

Sample Analysis About 2 ml of each sample was poured into sample containers for automatic injectors. The order of injection of samples was LSRG, HSRG, BN and SRK and each injection was considered three times. For each injection, the syringe was washed twice with acetone, and then twice with the sample. Then the syringe was filled and emptied 5 times and finally 0. μL of it was injected. After injection, the syringe was washed twice with acetone to minimize the effect of memory. To determine the concentration of components, after completing each analysis in the software, the status of the baseline and single start and end areas Single peaks were examined in all recorded chromatograms. After confirming their accuracy, the information about each chromatogram (surface area below the peaks and their retention time) is stored in a file with DCF extension. This file is opened in Dragon software with reference chromatogram. Compared to. The RF and RI for each compound are specified in the reference chromatogram. Using the available information, the software calculates and displays the values of the concentrations of the sample constituents in terms of weight percentage. Since the molecular weight, density and some other physical properties of hydrocarbons are recorded in the software bank, using it, the volume and molar percentage of each component of the sample as well as other physical properties of the sample such as density, bromine number, content Hydrogen, carbon, and octane numbers are also approximate. For light and heavy gasoline samples, DHA analysis and for BN and SRK samples, PIONA analysis is considered. Because for the last two samples, due to 96 having compounds of more than 10 carbons, DHA analysis is practically not very accurate and valid. On the other hand, in terms of process, at least in the oil refining industry, it is not necessary to know the amount of each component and determine the values in PIONA format. In the chromatogram of the crocin sample due to the large number of heavy isomers with close boiling point. Also, the presence of a rapid temperature rise at the end of the chromatogram leads to an increase in the height of the baseline at the end. Although this change is in an area where the peaks are largely unknown, failure to adjust the location of the baseline crossing also causes a gross error in determining the concentration of known species. For this purpose, the baseline was connected from the beginning of the first peak of this mass to the end of its last specified peak and the level below the peaks was calculated using the peg resolution in the software. In fact, this method is in contrast to the method in which the valley between the peaks is placed at the crossing of the baseline, which causes a negative error in measuring the heavy compounds at the end of the chromatogram. Isfahan refinery, integrated gasoline product and three intermediate products with the names of "mixed product" (product of gasoline isomerization unit), platform (product of catalytic conversion units) and reformate (product of CCR gasoline unit) for about 3 months and almost It was injected daily into the device. For each analysis, the octane number of the product obtained from the octane engine was entered into the library. Thus, at least 50 analyzes were recorded for each product. The octane number of a sample of the platform product was measured three times with an octane engine and 5 times with an infrared method and the results were used for statistical calculation.

Sample Analysis After calibration, the intermediate products and Euro-4 gasoline product were injected into the machine and the results were compared with the numbers obtained from the octane engine. This analysis was performed on samples of crude oil, atmospheric tower cap, light and heavy diesels, crocin. 97

The naphtha mixture was cut. Conversion of metals from organic to soluble salt was performed by acid digestion followed by ashing in the furnace. In this study, nickel, iron and lead were analyzed by plasma and sodium by atomic diffusion of acetylene flame and air. Since in the refinery laboratory, mainly vanadium metal is done by flame atomic absorption method and also high concentration of this metal in crude oil sample, acetylene-nitrous oxide flame atomic absorption method was used instead of ICP method. Measurement of ion concentration Sodium was released by the above-mentioned device for the first time in Isfahan refinery. This method is important because of the lack of need for sodium lamps and low detection and measurement limits. Due to the relatively high concentration of sodium in the samples, the use of ICP is also practically unnecessary. In addition, the ICP is a very expensive device, and assuming this research is used in other laboratories in the oil industry, unlike the atomic absorption and diffusion device, the ICP is not available everywhere.

Conclusion By conducting this research. This information includes the metal, hydrocarbon and sulfur content of these materials. Examination of the test methods was performed with higher accuracy and more complete compliance with the methods. The points that were left out of the standard, articles and books of the test subjects were identified and the capabilities of the devices in terms of detection and measurement limits and other variables were examined. In fact, this research has opened a small but clear window to more scientific and accurate experiments. All the topics of this research can be applied for the second and third distillation units as well as for Zuri catalytic units both in Isfahan refinery and in other refineries of our dear country. It is hoped that the process adopted in this research will be studied and used by all testers and officials of different departments of the laboratory of Isfahan Oil Refining Company and will help to achieve the goals defined in the company's vision

98 document. Objectives such as increasing the quality of services, customer satisfaction and observing economic and environmental considerations

Figures and Tables

Figure 1. Total Sulfur in Atmospheric Slices, Ton Per Day and Weight Percentage

Figure 2. Heavy Diesel HPLC Chromatogram

Acquiring the title of one of the top 100 companies in the Middle East, 2010 Obtaining a pollution-free certificate, 2010-2015

100

Research and Development / Summary of Implemented Student Projects

Title Minimization of Water Consumption and Effluent Production in Isfahan Oil Refinery Company (EORC)

Information Master Degree in Chemical Engineering

Abstract In recent decades, the lack of adequate water resources, the intensification of environmental constraints and increasing the price of water used in industrial processes, has led to more attention to reducing water consumption and wastewater production in process industries. Two general methods of mathematical programming and water-pinch technology have been developed for the integration of water-consuming and wastewater- producing processes. In this dissertation, while examining the two mentioned methods, we have optimized water consumption and effluent production of Isfahan oil refinery by mathematical planning method. Identifying key pollutants and limit inlet and outlet concentrations is a key factor in reducing water consumption and effluent production. In this case study, after determining this information, we examined the optimization of the refinery water network in the reuse mode (assuming the flow rates and concentrations of pollutants are constant). In this case, fresh water consumption decreased by 44% and production effluent by 19%. Then, taking into account the changes made in this review, we examined the economic calculations in order to

101 make the proposed plan more practical, and in this case, the rate of return on investment was equal to 21 months. In the next step, to further reduce fresh water consumption and production effluent, we designed a distributed treatment system. At best, the total treatment discharge was reduced by 24% and fresh water by 31%. In the last step, using sensitivity analysis, the effects of process change in the optimally designed models are investigated.

Description During the energy crisis of the 1970s, a team of chemical engineers at Yomist University, led by Professor Linhoff, introduced a new way to make the most of energy, called thermal pinch analysis. By using this method, significant results were obtained in operating costs and investment of energy consuming processes. Following this success in the 1990s, water pinch technology was introduced as a new tool for industrial issues, such as water reuse, wastewater minimization, and the design of wastewater treatment systems. In 1980, Takama et al. Considered the issue of optimal water allocation in a petrochemical refinery based on a superstructure, including all possible reuse and reproduction opportunities. This superstructure designed and optimized the system using a two-step approximation and the elimination of uneconomic combinations. Then in 1989, El-Helvaji and Manocytakis defined a composite curve (pollutant component) denoting mass exchange operation, using a methodology developed by Linhoff and Hindmarsch in heat exchange networks. They defined the scheme of synthesis or creation of mass exchange network (MEN) based on the preference of transferring key pollutants from rich to dilute streams [5]. In 1990, they incorporated this method into reproduction opportunities and applied it automatically. Paplexandri et al. (1994) proposed a similar method for synthesizing MEN based on the nonlinear programming method with MINLP integers, in which the superstructure network proposed by Floodas and Sirik (1989) was matched to the problem. Then more cases and applications of MEN synthesis problem were published. 102

In the same year (1994), Wang and Smith of the University of Manchester addressed the issue of water minimization differently, considering it as a matter of transferring pollutants from process streams to water streams, and flow information. They presented the concentration and rate of mass transfer as visible symbols. The method proposed by Wang and Smith, then developed by Cao (1996), entitled Throat Analysis, provided important insights into the problem of water system design. In this method, the concept of water limit profile was used to describe all water user operations. This allowed for a complete analysis of the water system based on common principles (Doyle and Smith, 1997). In fact, this concept has been accepted by other researchers in the field of water network integration. In addition to the drawing methodology proposed by Wang and Smith, Huang et al. (1999) proposed a mathematical model and solution to the combined problem of water allocation and wastewater treatment by nonlinear problem solving (NLP). Shortly afterwards, Bagajovich and Saulski (2000) turned to the use of linear models and linear programming (LP) to design water-using systems in process facilities, and then the same two with Kopel (2003) model Developed their linear networks to investigate networks without effluent into the environment. Finally, Smith, Kim and Savelsko (2005) studied the problem of water consumption minimization combined with energy minimization in related systems and then, the optimization of combined objective functions with the help of fuzzy linear programming has been targeted. The basic principles in data collection for water network are: ➢ Water Balance: Before examining a network in terms of water consumption and production effluent, it should be possible to establish a water balance for the entire network. ➢ Pollutants: The next step is to select the key pollutants that are more important than other pollutants and design based on them.

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➢ Discharge Constraints: Some processes require a constant flow of water (such as the compensatory flow of cooling towers). These processes must be identified. ➢ Accurate Data Collection: Water systems are usually complex and there is little information to study. Small data should be avoided at the beginning of the design. ➢ Limit Conditions: When determining opportunities for reuse, reuse, and recirculation recovery, the first step is to determine water limit information. This information indicates the maximum number of acceptable contaminants in the water for a process. If all pollutants are considered, network solution will be very complicated due to their multiplicity. If only a limited number of pollutants are considered, some contaminants that are not considered may affect a process. If we consider the allowable values below the limit, the consumption of fresh water and produced effluent cannot reach its minimum amount because we have not considered some opportunities for reuse of water. Conversely, if the permissible limit values are above the actual value, some processes may not be performed normally. Therefore, with the help of the rules stated below, the appropriate key pollutants and permissible concentrations of the input limit and We determine the output.

Existing Rules for Finding Key Pollutants and Permissible Concentrations of Input and Output Limits 1- Corrosion limitations, maximum solubility, unit study through simulation and laboratory studies can be useful in determining information. 2- Using sensitivity analysis is a useful method to determine limit pollutants. In this way, we draw the flow chart of fresh water in terms of inlet concentration. Then, by increasing the inlet concentration, we 104

observe the changes in the fresh water flow rate. We continue this process until adding the inlet concentration has no effect on the fresh water flow rate. The obtained concentration can be considered as a limit concentration. To be surer, we test the result by testing or simulating the unit. 3- We select those pollutants that have obvious effects on the processes. Other contaminants can be considered as constraints after the initial network has been prepared. 4- Combine pollutants that have similar effects. To reduce the number of pollutants to facilitate the solution of the mathematical model for water integration, some pollutants that have similar effects can be combined. For example, if the effect of Ca and Mg is to harden water, the total hardness can be used as a contaminant, instead of Ca and Mg alone. 5- The limit concentrations of the input pollutants are regulated in such a way that for the processes in which the use of pollutants is prohibited, they are set equal to zero, ie the water used from other processes that contain pollutants cannot be used. These processes should be used. 6- For processes, where water is a process fluid, or water contains some impurities that cannot be reused at all by other processes, the output concentration is set to a maximum, so that other processes drain water. Will not be used. 7- Water loss for normal processes is ignored. Because the amount is almost "small" and can be added to the final design of the grid, this can make the mathematical model and solution procedure easier. As long as the water loss is relatively small, it should be discarded. Mathematical optimization obtains the least amount of fresh water using the constraints defined by the design engineer. This method gives the engineer less insight and understanding of how to form a water consumer network compared to blue pinch technology. However, in some cases (large multi-pollutant systems) this method is superior to pinch technology. 105

Conclusion Blue pinch technology in multi-pollutant systems achieves the lowest fresh water flow rate and the optimal water network by a quantitative balance for the mass charge of the pollutant transferred from the water-consuming process to the watercourse at different boundary concentrations. This border-to-border study is a very difficult and tedious task. In comparison, the mathematical optimization described in this dissertation can easily include systems containing multiple pollutants. In many cases, the same result is obtained from both methods. However, it is clear that mathematical optimization will be a more effective tool in some cases. In this dissertation, after presenting the existing methods in minimizing water consumption / wastewater production, we examined the water network of Isfahan Oil Refinery. Initially, using the existing rules in determining the limit pollutants and permissible inlet and outlet concentrations, the pollutants and their permissible inlet and outlet quantities have been determined. We paid for water consumption and wastewater production. In this step, UMIST / WATER1.7 software is used to solve the nonlinear programming model. After performing the optimization on the water network, the following results are obtained.

Table 1. Results from the Refinery Water Network Optimization in Reuse using UMIST / WATER1.7 Software

m 3 Total discharge of fresh water before optimization ( ) hr 518 Total discharge of fresh water after optimization 29/16 Total effluent discharge before optimization 530 Total discharge of effluent after optimization 428 44% Percentage reduction in the flow of fresh water 19% Percentage reduction in effluent discharge

The obtained optimal network can now be compared with the current refinery network.

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Figures and Tables

Figure 1. Isfahan Refinery Water Consumption Network

Figure 2. Optimal Refinery Water Network in Reuse Mode Using UMIST/WATER 1.7 software

Figure 3. Investigation of the Effect of Change in the Total Annual Cost with Respect to the Cost of Fresh Water

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Figure 4. Distributed Wastewater Treatment System Obtained for the Refinery by GAMS / MINOS Software

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Second and third place in the environment among oil refining companies - 2013 and 2014

HSE rank, safety and passive defense among oil refining

companies 2011-2015

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Research and Development / Summary of Implemented Student Projects

Title Application of Electric Field in Amplification of Mass Transfer Phenomenon to Separate Sulfur Dioxide Compound from Gas Stream

Information Master Degree in Chemical Engineering

Abstract Polar pollutants such as sulfur dioxide are extremely harmful to living organisms and the environment. There are different ways to remove this substance. In recent years, a new method based on the use of electrohydrodynamic force along with traditional methods has been proposed. In this dissertation, an experimental system was designed and fabricated to experimentally evaluate the effect of electrohydrodynamic force on the efficiency of the sulfur dioxide reduction / removal system from a mixed gas stream. The experimental results showed that the efficiency of the system in removing sulfur dioxide depends on the amount of applied voltage, gas flow rate, concentration of sulfur dioxide in the passing gas flow, and concentration of sodium hydroxide in the inlet adsorbent. The application of electro-hydrodynamic force increases the intensity of transfer of sulfur dioxide molecules from the gas phase to the sodium hydroxide liquid film and enhances the mass transfer coefficient. The results show that the system efficiency is normally about 40%. By applying an electric field with a voltage difference of 15 kV and while the concentration of sulfur dioxide at the gas inlet was equal to 520 ppm, and the

110 intensity of the gas flow was 10 liters per minute and the intensity of the adsorbent current was 0.01 cubic meters per minute (base conditions). Sulfur dioxide removal efficiency was measured as 74.4% (baseline conditions). By creating the basic conditions and only by increasing the gas flow rate to 20 liters per minute, the efficiency of the system reached 62.5%. Laboratory results show that a voltage difference of 15 kV is applied to the electrodes of the system and in case the concentration of sulfur dioxide in the inlet gas flow with a flow rate of 10 liters per minute is equal to 2500 ppm, and the absorbent liquid flow rate is 0.01 cubic meters per minute, system efficiency to 82.28 percent. Under basic conditions and only by reducing the concentration of sodium hydroxide in the inflow of adsorbent fluid to 0.01 normal, the efficiency of the system reached 54%. By creating the basic conditions and only by reducing the voltage of the electric field by 12 KV, the efficiency of the system reached 68.5%, and by reducing it to 6 KV, the efficiency of the system reached 50.5%.

Description Most solid, liquid, and gaseous fuels contain sulfur, and approximately 95% of the sulfur contained in combustion is converted to sulfur dioxide, the rate of conversion of which depends on the type and number of compounds in the fuel and combustion conditions, including temperature and oxygen content. In addition to the combustion process, this pollutant is also produced during various industrial processes. Sulfur dioxide is an important environmental pollutant and can cause a variety of damage to the health of living organisms and the ecology of the environment in a variety of ways, including acid rain and respiratory problems. The information obtained from previous research paved the way for the construction of an optimized laboratory system that has better performance than previous works. Among the changes made in this regard is the use of a wet wall tower plasma reactor instead of a rectangular cube reactor, which increased the gas-liquid interface.

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To eliminate or reduce the very adverse effects of this pollutant, various desulfurization processes have been developed and expanded over time. Traditional sulfur dioxide removal processes are a simple mass transfer phenomenon with a chemical reaction that during the created conditions, the combination of sulfur dioxide is absorbed by a medium or reacts chemically with the active substance in this medium and from the contaminated stream to this material. Sodium hydroxide, water and ammonia are some of the substances that can absorb and react with sulfur dioxide. During the removal process, the sulfur dioxide compound must be transferred from the gas phase to the interface and enter the liquid phase, and after reacting with it, it must be converted to another compound and eliminated. Therefore, this process is a complete mass transfer process the voltage difference can have a significant effect on reducing the pollution rate of the polluted gas stream. For this purpose, for a condition where the intensity of the polluted current is 10 liters per minute, the sulfur dioxide concentration is 520 ppm and the sodium hydroxide concentration passing through the plasma reactor is 1. The concentration at the output of the plasma reactor was measured at 0. 0, 3, 6, 9, 12, 15 KV. In these experiments, because sodium hydroxide was returned to the sodium hydroxide tank after entering the plasma reactor, the concentration of sodium hydroxide in the tank was calculated regularly by titration so as not to deviate too much from the desired amount and did not affect the accuracy of the tests. The range for sodium hydroxide changes is 0.95 to 1.05 of the value presented in each section. It should be noted that the flow rate of sodium hydroxide during these experiments was stabilized at 0.01 cubic meters per minute and experiments in 5 different concentrations of 520, 1030, 1525, 2020, 2500 ppm of sulfur dioxide in the gas stream Input contamination was performed. The results of the experiments can be summarized as follows: As the concentration of sodium hydroxide at the inlet to the plasma reactor increases, the concentration of sulfur dioxide in the exhaust gas stream decreases.

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So that the removal efficiency in the case of using 15 KV voltage increases from 54% if the concentration of sodium hydroxide is 0.01 normal to 74% when the concentration of sodium hydroxide is 0.1 normal. With decreasing airflow intensity, a decrease in the amount of sulfur dioxide concentration in the exhaust gas flow was observed. So that the removal efficiency in the case of using 15 KV voltage increases from 62% if the air flow intensity is 20 liters per minute to 74% if the air flow intensity is 10 liters per minute.

Conclusion As the amount of pollution in the inlet gas flow increased, the amount of this pollution in the exhaust stream also increased, but the amount of pollution removal efficiency increased. So that the removal efficiency in the case of using 15 kV voltage increases from 74% in case of sulfur dioxide concentration of 520 ppm to 82% in case of sulfur dioxide concentration of 2500 ppm. Also, applying an electric field increased the average sulfur dioxide removal efficiency from 40% to 80% compared to the non-sulfur state. The amount of electric current used in the system is in the range of milliamperes (1 milliamperes), so the power consumption of the device is low (less than 20 watts). On an industrial scale, the project is expected to be economically viable, but this requires further research.

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Figures and Tables

Figure 1. Shows the changes in sulfur dioxide concentration in the output stream according to the voltage change applied to different concentrations of sulfur dioxide composition in the inlet gas stream (intensity of polluted air flow: 10 liters per minute, sodium hydroxide concentration: 0.1 normal)

Figure 2. Demonstration of sulfur dioxide removal efficiency in terms of voltage change applied to different concentrations of sulfur dioxide composition in the incoming gas stream (intensity of polluted air flow: 10 liters per minute, sodium hydroxide concentration: 0.1 normal)

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Figure 3. Shows the changes in sulfur dioxide concentration in the output current according to the voltage change applied at different concentrations of sodium hydroxide inlet sorbent (inlet sulfur dioxide concentration: 520 ppm, inlet air flow intensity: 10 liters per minute)

Figure 4. Shows the removal efficiency changes according to the voltage change applied at different concentrations of sodium hydroxide inlet adsorbent liquid (concentration of sulfur dioxide inlet gas: 520 ppm, inlet air flow intensity: 10 liters per minute)

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Figure 5. Shows the changes in the concentration of sulfur dioxide in the outlet flow according to the voltage change applied to the intensity of different air currents (concentration of sulfur dioxide inlet gas: 520 ppm, concentration of sodium hydroxide in the inlet adsorbent liquid: 0.1 normal)

Figure 6. Demonstration of sulfur dioxide removal efficiency in the output stream according to the voltage change applied at different air flow rates (concentration of sulfur dioxide inlet gas: 520 ppm, concentration of sodium hydroxide in the inlet adsorbent liquid: 0.1 normal)

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The first rank of research from the 11th Festival of Top

Public Relations of Iran, 2013

Second place in media relations from the 11th Festival of

Iran's Top Public Relations, 2011 and 2012

117

Research and Development / Summary of Implemented Student Projects

Title Desulfurization of Light Hydrocarbon Sections by Oxidation (ODS) Method

Information Master Degree in Chemical Engineering

Abstract Oxidation desulfurization process (ODS) is one of the desulfurization processes that has many advantages such as mild operating conditions. In this study, desulfurization of light oil sections by oxidation method has been investigated. Two hydrocarbon sections of kerosene with a total sulfur content of 2335 ppm and a diesel section with a total sulfur content of 7990 ppm have been selected for the studies. By evaluating different oxidation systems, an oxidation system consisting of oxygenated water-formic acid was selected for the oxidation of sulfur compounds in hydrocarbon sections. The effect of effective parameters on the performance of the oxidation system including temperature, molar ratio of oxidant to sulfur (O/S), and molar ratio of formic acid to sulfur (Acid/S) of desulfurization from two hydrocarbon sections was studied and it was found that suitable oxidation conditions for hydrocarbon sections, it is O/S = 5, Acid/S = 30 and the oxidation temperature is 60 oC for kerosene section and 80 oC for diesel section.

Description Based on the appropriate oxidation conditions, a new reactor system was proposed and constructed using the collision jet technique, equipped with four jets in the

118 mixing chamber (FIJR), for the oxidation of sulfur compounds in hydrocarbon sections. The performance of FIJR reactor for oxidation of sulfur compounds in kerosene cutting was evaluated and the effect of effective parameters on reactor performance such as flow rate, jet diameter, Reynolds number of jets and distance between jets was studied. FIJR reactor performance improved with increasing current intensity, decreasing jet diameter, increasing jet Reynolds number, and decreasing nozzle spacing. The best operating conditions of FIJR reactor in the range of studied parameters led to 92% desulfurization of kerosene section after oxidation and extraction of solvent- oxidized sulfur compounds. Also, the performance of this reactor was compared with a conventional agitator reactor under the same process conditions and it was found that the jet reactor is more suitable for this application. Separation of oxidized sulfur compounds from hydrocarbon sections by liquid-liquid extraction method was studied in detail. The effect of parameters such as solvent type, volume ratio of solvent to hydrocarbon section and number of extraction steps on desulfurization rate and recovery of hydrocarbon section after extraction were studied. Finally, by considering both desulfurization and shear recovery effects in a parameter called solvent efficiency factor, E, the performance of different solvents was compared and it was found that among the selected solvents, the performance is (acetonitrile> methanol> ethanol 96%). It was also found that increasing the number of extraction steps by more than two steps for kerosene cutting and three steps for diesel cutting does not have much effect on improving desulfurization but significantly reduces the recovery rate after extraction. In these studies, it was found that by applying appropriate oxidation conditions and extracting oxidized sulfur compounds from hydrocarbon sections, desulfurization of more than 99% can be achieved. Therefore, by using the desulfurization process by oxidation (ODS) method alone or in combination with other desulfurization

119 processes, it is possible to reach new strict standards on the amount of sulfur in hydrocarbon sections. In this study, desulfurization of petroleum sections between distillation of kerosene with initial sulfur content of 2335 ppm and diesel with initial sulfur content of 8000 ppm was investigated and the following results were obtained: 1- Oxygenated Water Oxidation System-Formic acid has more advantages than other oxidation systems such as the simplicity of the oxidation system, the availability of formic acid as a catalyst, and the need for no solvent and solid catalyst in the oxidation medium. The title of the main oxidation system was considered in this study. 2- The most important parameters of the oxidation system of oxygenated water - formic acid include the oxidation temperature, the molar ratio of hydrogen peroxide to sulfur (O/S), and the molar ratio of formic acid to sulfur (Acid/S) that the effect of these parameters on desulfurization Hydrocarbon sections of kerosene and diesel were investigated. It was found that the best oxidation conditions within the studied parameters are for cutting kerosene (O/S =5, Acid/S= 30, T= 60 oC) and for cutting diesel (O/S =5, Acid / S =30, T=80 oC). 3- The reaction system of oxidation of sulfur compounds is a liquid-liquid system. In this system, there may be limitations to the interphase transfer phenomena that control the reaction rate. Therefore, in developing a reactor system suitable for this application, a reactor that provides intense interphase mixing seems appropriate. For this reason, a reactor system based on the technique of collision jets equipped with four jets in the mixing chamber (FIJR) was proposed and built for this purpose. By studying the effect of the most important design and operational parameters on reactor performance such as flow intensity, jet diameter, distance between jets, it was found that reactor performance improves with increasing current intensity and decreasing jet diameter and distance between nozzles. Suitable conditions in the 120

range of studied parameters were equal to the flow intensity of 400 L/h, jet diameter of 2 mm and distance between jets of 1 cm. The performance of the FIJR reactor under these conditions for the oxidation of sulfur compounds in kerosene cutting under suitable oxidation conditions resulted in 92% desulfurization of kerosene cutting. 4- The performance of the new FIJR reactor was compared with a conventional STR agitator reactor and it was found that under similar conditions in terms of residence time and reactor input power, the performance of FIJR reactor in oxidation of sulfur compounds is significantly superior to STR reactor. 5- In the case of the STR reactor, it was found that increasing the agitator speed beyond a certain limit of 750 rpm has no effect on improving the performance of the reactor and only increases the power consumption. 6- During the oxidation of sulfur compounds, sulfoxides and sulphones are formed, which have a much higher polarity than the primary sulfur compounds. Depending on the molecular structure, the sulfonates produced either remain in the hydrocarbon fraction, are either extracted by the aqueous phase of the oxidation medium, or remain insoluble and precipitate in both phases. Therefore, during oxidation, some of the sulfur compounds are separated and some desulfurization is done from the cut. The results of our experiments showed that in case of oxidation of sulfur compounds under similar conditions to suitable oxidation conditions, more than 73% desulfurization from kerosene cutting and about 40% desulfurization from diesel cutting is done only in the oxidation stage. Secondary processes such as liquid-liquid extraction to separate the oxidized sulfur compounds remaining in the hydrocarbon section and to improve the desulfurization of the hydrocarbon section go beyond these values. 7- Liquid extraction process-Liquid is the most important process for separating oxidized sulfur compounds from hydrocarbon slices. The 121

most important parameters of the liquid-liquid extraction process are the type of solvent, the number of extraction steps, and the volume ratio of the solvent to the hydrocarbon section. In order to regulate these parameters in the process of extracting sulfur compounds from hydrocarbon cutting, in addition to desulfurization, it is necessary to pay attention to the recovery of the cut after extraction. In this study, after the initial selection of methanol, 96% ethanol and acetonitrile solvents based on common criteria, the effect of each of these parameters on the rate of desulfurization and shear recovery after extraction was studied for each solvent. Then, by combining both desulfurization and shear recovery effects in a factor called solvent efficiency factor, E, a comparison was made between the performance of different solvents:

(Acetonitrile > Methanol > Ethanol 96%)

It was also found that increasing the number of extraction steps by more than 2 for kerosene cutting and more than 3 for diesel cutting has little effect on increasing desulfurization but causes a continuous decrease in shear recovery after extraction. The same is true for the volume ratio of solvent to S/F hydrocarbon cut, increasing S/F beyond a certain limit has no effect on improving desulfurization, while continuously reducing the shear recovery rate after extraction. 8- After extraction of oxidized sulfur compounds from hydrocarbon sections, the maximum desulfurization rate observed for both kerosene and diesel sections was more than 99% and the lowest amount of sulfur remaining after the ODS process for the cutting of kerosene was 13.3 ppm and for cutting diesel it was 40 ppm, which are lower than the Euro 5 standard (the current standard in our country). 9- By comparing the amount of desulfurization obtained in the simple extraction process with the oxidation-extraction process (ODS) and the existence of a large difference in the amount of desulfurization in favor 122

of the ODS process, it was found that the role of oxidation stage in desulfurization of hydrocarbon sections Is the color. Because in the oxidation stage, firstly, some of the sulfur compounds are separated, and secondly, the properties of the sulfur compounds remaining in the cut, such as polarity, change in such a way that it is possible to separate them by the extraction process. 10- Adsorption process alone is not suitable for the separation of oxidized sulfur compounds from hydrocarbon sections with high sulfur content such as hydrocarbon sections presented in this study because due to limited adsorption capacity of adsorbents in the separation of oxidized sulfur compounds, it is possible. Achieving high desulfurization (beyond 90%) is not possible in this method. Also, high concentrations of oxidized sulfur compounds in the cut lead to the phenomenon of adsorption saturation in a short time. On the other hand, by using the adsorption process after extraction, some of these problems are solved and it is possible to achieve hydrocarbon sections with low sulfur content.

Conclusion Due to the breadth of the present studies, suggestions are presented separately in each section: In the section on experimental studies of oxidation of sulfur compounds, the following items are presented as suggestions: 1. Determining the main sulfur compounds of hydrocarbon sections and their amount: It seems interesting to study the conversion rate of different sulfur compounds after oxidation and their separation after extraction with solvent. For example, it is very interesting to determine what the total amount of sulfur left after the desulfurization process by oxidation (ODS) consists of. In this study, at first, such an attempt was made, but due to the many limitations in the qualitative and quantitative analysis of sulfur compounds, it was not possible to do so. 123

Because, firstly, special analysis devices (gas chromatography device equipped with PFPD detector and new GC-MS devices with high scanning quality) are required for this purpose, and secondly, for conducting small studies of this kind and producing control solutions, to special sulfur compounds such as 4,6-DMDBT, which is very expensive, while not available in Iran and is produced in the world only for desulfurization studies in very small quantities. 2. Mechanistic studies to determine the contribution of the effect of transfer phenomena and chemical kinetics in the overall speed of the oxidation process: For this purpose, it is necessary to first oxidize individual sulfur compounds such as DBT and BT in solvents such as toluene in the oxidation system under different conditions such as (Different temperatures and different mixing speeds) should be studied and then by interpreting the results and using criteria such as modules, the general regime controlling the process speed should be determined. This information is very important in developing suitable reactors for this application. 3. Investigate the possibility of increasing the overall process speed: Examining the application of conditions such as the use of ultrasonic wave energy in the reaction mixture, or the addition of associated catalysts along with formic acid to increase the overall process speed is an interesting topic for future studies. Increasing the overall oxidation rate leads to ease of reactor design, reduction of reactor volume and the possibility of continuous process design. In the proposal and construction of the reactor based on the collision jet technique, the following items are suggested: ➢ Optimization of the number of jets in the reactor mixing chamber: By economic calculations, taking into account the increase in power consumption and performance improvement obtained by increasing the number of jets, the optimal number of jets is obtained. As you 124

know, as the number of jets in the reactor mixing chamber increases, the reactor performance is likely to improve, but at the same time the power consumption will increase. Optimizing the number of jets with economic calculations is an interesting topic for future studies. ➢ Determining the effective parameters in increasing the scale of jet reactor: Due to the fact that increasing the scale of this type of reactors as special reactors is not easily possible, for this purpose it is necessary to build at least one other FIJR reactor with different scale and its performance in oxidation Sulfur compounds are evaluated. Then try to determine the numbers without the main dimension by evaluating the results obtained in reactors with different scales. In the studies conducted in the present study, it seems that the Reynolds Jet number is one of the main parameters in this field. ➢ Study of jet failure and alliance trends: Knowing this information is important in designing reactors based on collision jet techniques. The study of the use of various computational techniques such as computational fluid dynamics (CFD) to model the failure and cohesion of jets is an interesting topic for future studies. In the experimental studies section on the separation of oxidized sulfur compounds from hydrocarbon fractions, the following are interesting for future studies: Comparative study of the performance of ionic solvents with ordinary solvents: ➢ For this purpose, first some ionic solvents that are probably suitable for this application and can be synthesized should be selected and their performance in the separation of compounds. Oxidized sulfur from hydrocarbon sections should be evaluated. Then, the desulfurization rate and the recovery rate of the hydrocarbon section obtained if these and conventional solvents are used should be compared. Of course, if the performance of ionic solvents is better, it is necessary to replace ordinary solvents with ionic solvents, such as 125

how and the possibility of recovery of ionic solvents after the process, as well as economic issues related to these solvents. (Their high price) should be carefully evaluated. ➢ Investigation of solvent recovery processes after extraction: For this purpose, the processes of solvent recovery after extraction and the separation of sulfones and hydrocarbons dissolved in the solvent should be carefully studied. Solvent recovery by distillation is currently proposed, but various aspects of this separation process should be considered. For example, it must be determined how much solvent is lost with the sulfonate-rich stream and how much fresh solvent is needed accordingly. It is also necessary to determine what part of the hydrocarbons that are transported by the solvent during the extraction step can be recovered at this stage. ➢ How to manage the production of sulfonated waste: For this purpose, all the forthcoming solutions in a refining complex for the management of this waste should be evaluated. For example, the possibility of sending this product to sulfur recovery units after the necessary preliminary processes, as well as the possibility of converting this waste into sulfonates which are valuable materials, or even the possibility of using this waste in sulfur asphalts should be studied and Make an accurate comparison and suggest the best solution. Recently, solutions such as the possibility of using bilayer

hydroxide catalysts to separate SO2 from sulphones and recover the hydrocarbon fraction have been considered by researchers, which need to be further evaluated. ➢ Evaluation of different adsorbents for separation of oxidized sulfur compounds: Considering the development of different adsorbents with different properties and characteristics, evaluation of the performance of these adsorbents in the process of separation of oxidized sulfur compounds seems interesting. Interpretation of the 126

performance of adsorbents in the separation of oxidized sulfur compounds from hydrocarbon sections with pore structure (pore size, percentage of meso and micro porosity) and their specific surface area is one of the interesting research fields in this regard. If a suitable adsorbent with a high adsorption capacity is found for oxidized sulfur compounds, it will be possible to replace the extraction process with adsorption process to separate the oxidized sulfur compounds. However, with sufficient studies, the existing ambiguities about the adsorption process such as adsorbent capacity, the possibility of reducing the adsorbent and how to reduce it, the total lifespan of the adsorbent and the number of times the adsorbent can be reduced, which is good for future studies.

Figures and Tables

Figure 1. FIJR Reactor Mixing Chamber

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Figure 2. STR Reactor System for Oxidation of Sulfur Compounds in Hydrocarbon Sections

Figure 3. Apparatus for Studying the Effect of Various Parameters of the Oxidation System

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Receiving the National Award for Productivity and

Organizational Excellence, 2007, 2008 and 2009 Winning the title of "Top Research and Development Products" in the 5th Industry, Mining and Trade Research and Technology Festival in 2016

129

Research and Development / Summary of Implemented Student Projects

Title Recovery of Nickel and Tungsten from Used Hydrocracking Catalysts of Isfahan Oil Refining Company

Information Master Degree in Chemical Engineering

Abstract Catalysts play an important role in various industrial processes and accelerate the reaction, improve product quality, reduce energy consumption and ultimately reduce the cost of a process. Catalysts used in refineries lose their catalytic activity after several years of use and are known as used catalysts. Disposal of these catalysts, which contain heavy metals, is environmentally hazardous. This study investigates the possibility of recovering nickel and tungsten from used catalysts (Ni/W) in the hydrocracking unit of Isfahan Oil Refinery. In the two-step recovery process, nickel is first recovered as a solution by sulfuric acid, nitric acid, hydrochloric acid as the extracting acid, and the parameters affecting the recovery time of the nickel and the concentration of nickel are reduced. Consumption, particle size and stirring speed of the reaction mixture were investigated. The final product obtained is nickel oxide particles, which is obtained by a two-step process of precipitation by sodium hydroxide and calcination at a temperature of 700-650 °C. Then, in the second stage, recovery of the remaining used catalyst from the first stage is exposed to bases such as sodium hydroxide and potassium hydroxide, and the existing tungsten is recovered as a brown solution of

130 sodium tungstate (Na2WO4). Reaction The ratio of solid catalyst to acid consumption, particle size and stirring rate of the reaction mixture is investigated. The final product obtained is tungsten oxide particles, which is obtained by a two- step process of precipitation by hydrochloric acid and calcination at a temperature of 650-600 °C.

Description Catalysts are substances that increase the rate of a reaction in a chemical process by reducing the activation energy. However, they are not consumed in these reactions and can also be recovered. Among the characteristics of a good catalyst are factors such as acceleration of reaction, high activity, good selectivity, mechanical and thermal resistance. A catalyst consists of two parts, the active phase and the catalytic base. The active phase includes metals such as nickel, tungsten, molybdenum, cobalt, gold, platinum, etc., and compounds such as alumina, silica, etc. are used as the catalytic base. The catalytic base accounts for about 90-85% of the total weight of the catalyst. Forms. These bases are used to increase the contact surface of reactants and active metals. The oil industry is one of the largest consumers of catalysts, which due to the growing use of petroleum products, the use of catalysts is also increasing. The annual consumption of catalysts in refining operations is currently about 700 tons and the average value per kilogram is $ 25, which is mainly imported. Catalysts used in refineries are mainly divided into four categories: Hydrogen production unit catalysts (HTSC, LTSC), ISOMAX, Catalyst Platformer Unit, catalyst Sulfur Unit, Catalysts used in refineries lose their catalytic activity after several years of use. For this reason, these catalysts regain their activity and re-enter the cycle by using methods such as oxidation in the presence of oxygen, reduction of hydrogen gas at high temperature, calcination and chlorination. Catalysts, after several reductions, are no longer able to be used in processes and cannot have their primary effect on reactions quickly. For this reason, they are removed from the reactor. These catalysts are called used catalysts and the main basis of this project is work on used catalysts. 131

Environmental Problems Catalysts lose their efficiency after 2-3 year periods of use, so they are discharged from the reactor. In the past, there were two behaviors, one was to bury used catalysts in the ground and the other was to keep it in storage. In the first method, because most of these catalysts contain heavy elements, so these elements are absorbed by water and soil and have environmental consequences. The second method also requires a high cost. In recent years, due to the importance of environmental issues and the passage of international law, used catalysts are considered hazardous waste and are not allowed to be buried in industry.

Value of Used Catalysts Due to the fact that these catalysts contain precious metals such as nickel- tungsten-molybdenum-cobalt-gold-silver, etc., therefore, used catalysts have been considered as secondary sources of metal in recent years.

Necessity and Importance This research project is based on environmental issues, so with the production of the least volume of waste can be used on an industrial scale. Another point is the economic importance of the project that this project can be highly profitable with the participation of industries with high economic justification. This project is also an effective step in industrial waste management. If we want to refer to the current situation, we must say that due to the lack of recovery technology in the country, these high-tonnage catalysts are exported to European countries such as the Netherlands and France. These countries are also not willing to invest and transfer technical knowledge to our country for many reasons. Therefore, considering that a large area of our dear country is dedicated to the petrochemical industry and oil refineries and ancillary industries, this backwardness should be compensated in this sector by applying proper management and using the knowledge of local experts, as well as proper investment. Used due to the presence of heavy metals in their structure, if buried in the ground or deep in the sea, they will 132 cause many problems. So, the only solution to get out of the crisis is to recover these heavy metals from used catalysts. At first glance, it is thought that this requires a high cost and investment. However, if this is achieved and metal recovery technology is achieved, due to the global shortage of metals from mines and their high value, in addition to offsetting the initial costs, their benefits can be exploited for years. Used can be named as secondary sources of metal because the recovery of used catalysts can be in addition to solving environmental problems, a source for the production and supply of metals such as nickel, tungsten, cobalt, silver, molybdenum. In our country, about 5000 tons of used catalysts are produced annually, which includes refinery catalysts, petrochemicals, pharmaceutical industries, steel, etc. This statistic shows that the production of catalysts in the country is high, so the vacuum of recovery technology Metals is showing themselves significantly. Those in charge can take an effective step in overcoming this backwardness by trusting in-house experts and proper investment. Project Objectives: The main objectives of the nickel and tungsten recovery project are as follows: 1- Development of nickel-tungsten recovery process from used refinery catalysts 2- Studying the effect of different solvents on the recovery rate of nickel- tungsten from catalysts used and selecting the best solvent 3- Examining the economic aspect of the process 4- Reducing the adverse environmental effects caused by the release of the above wastes. In addition, one of the practical goals of this project is that after the successful implementation of the project on a laboratory scale, it can be examined in semi- industrial and industrial conditions. Implementing this plan will generate millions of dollars of profit for the country annually and prevent the release of used catalysts that contain precious metals. Extensive research on the recovery of other metals from used catalysts was also conducted. In 1983 on the leaching with 70-60% nitric acid at 120 °C. 133

In 1975, Ivascano and Roman conducted research on the extraction of nickel from alumina-based catalysts in an ammonia unit. In this study, acid leaching with sulfuric acid was investigated and about 99% of the nickel in the catalyst was recovered as nickel sulfate when the acid concentration was 80%, the reaction temperature was 70 °C and the reaction time was 50 minutes. In 1986, Wickol et al. Examined the washing of used catalysts with an aqueous solution of 15-23% ammonia at 90-60 °C and pH = 7.5. In 1991, Floara et al. Obtained the optimum conditions for the nickel elution from alumina base catalysts using (NH4) 2CO3 at 80 °C. Extensive research has also been done on the recovery of other metals from used catalysts. In 1971, Gutnikov investigated the washing of used catalysts with an aqueous solution containing ammonia and ammonium salt at 110 °C for half an hour to recover vanadium, cobalt, and nickel. In addition to the hydrometallurgical methods used to recover metals, research has been conducted on pyrometallurgical methods for metal recovery. In 1973, Tuviner studied the recovery of copper and nickel by the oxidation process of iron sulfate at high temperatures. In all the proposed methods, the percentage of metal extraction in the optimal conditions of the recovery process is reported in the range of 95-80%. In a recent study, Bosnardo et al. In 2007 studied a process for the recovery of metals such as molybdenum, nickel, and cobalt, in which, based on the process of acid melting with KHSO4, these metals are water-soluble salts. Temperatures of 600- 350 °C are recovered in 0.5-7 hours. The extraction rate for each of these metals in this study is reported in the range of 85%. Despite extensive research in the world on the recovery of metals from used catalysts, this issue has not been well received in Iran. The researches and researches done are also transient and unreliable studies. However, a few examples of this research can be mentioned. In this regard, research on the recovery of nickel and tungsten from used hydrocracking catalysts has been conducted by Mohabeli and Islami. 134

Also, research on metal recycling from catalysts used in the oil and petrochemical industries by Soleimani has been conducted, in which the possibility of recovering various types of metals. It has been studied and the necessity of doing it has been emphasized according to environmental and economic reasons. In a study on the recovery of vanadium from used catalysts and ores, vanadium is separated by sodium carbonate salt through an alkaline purification process and precipitated with 95% purity. Despite extensive research in the world on the recovery of metals from used catalysts, this issue has not been well received in Iran. The researches and researches done are also transient and unreliable studies. However, a few examples of this research can be mentioned. In this regard, research on the recovery of nickel and tungsten from used hydrocracking catalysts by Mohabeli and Islami has been carried out. Also, research on the recycling of metals from catalysts used in the oil and petrochemical industries has been conducted by Soleimani, in which the possibility of recovery of various metals has been investigated and the need for it has been emphasized due to environmental and economic reasons. In a study on the recovery of vanadium from used catalysts and ores, vanadium is separated by sodium carbonate salt through an alkaline purification process and precipitated with 95% purity.

Raw Material Specifications The catalyst used in this research is one of the catalysts of the hydrocracking unit of Isfahan Oil Refinery. As mentioned in this unit, heavy petroleum hydrocarbons are converted into high quality and high consumption products. The Ni-W catalyst used in this unit is made by criterion company and has the brand name Z503. This catalyst can be used in three periods of two years, which usually loses its catalytic activity earlier than this date and then disposed of as a used catalyst.

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Chemical Analysis of used Catalysts in Isfahan Oil Refining Hydrocracking Unit XRF First, before the tests, the initial amount of nickel and tungsten in the used catalyst as well as other compounds were determined using XRF.

Table 1. XRF analysis for the desired catalyst

Std Err Compond Wt% stderr EL Wt%

Sio2 36/96 0/24 Si 17/28 0/11 Al2o3 33/71 0/24 Al 17/84 0/13

Wo3 18/43 0/19 W 14/61 0/15 Nio 4/55 0/10 Ni 3/57 0/08

So3 3/11 0/09 Sx 1/24 0/03 Cao 1/38 0/06 Ca 0/990 0/042 Fe2o3 0/996 0/05 Fe 0/696 0/035

MoO3 0/156 0/012 Mo 0/104 0/008 Hgo 0/150 0/054 Hg 0/139 0/0050

P2o5 0/127 0/006 Px 0/0553 0/0028 Mgo 0/118 0/011 Mg 0/0711 0/0065

Na2o 0/090 0/018 Na 0/067 0/013

Tio2 0/0852 0/0043 Ti 0/0511 0/0026

K2o 0/0327 0/0021 K 0/0271 0/0018

0/0313 0/0025 Cl 0/0313 0/0025

Investigating the Effective Factors on Nickel and Tungsten Recovery and Determining the Optimal Conditions At constant temperature of 80 °C, time 2 hr, size 200 mesh, solid to liquid ratio was considered 1.5. The results are obtained in the form of the following diagram.

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Effect of stirring velocity on persentage conversion

120

100

H2SO4 80 HNO3 60 Hcl

Aqua regia 40 % conversion% 20

0 1000 800 600 400 200 100 stirring velocity in rpm

Figure 1. Effect of Stirring Speed on Nickel Extraction Percentage

Effect of Stirring Speed on Tungsten Extraction Under constant conditions with temperature of 80 °C, time 1hr, particle size 200 mesh, S/L equal to 1.2, the results in the following diagram show that with increasing the stirring speed of the reaction mixture, the recovery rate of tungsten increases.

Effect of stirring velocity on percentage conversion 100

80 60 NaOH 40 20

0 % % Conversion 1000 800 600 400 200 100 Stirring Velocity in rpm

Figure 2. Effect of stirring speed on tungsten extraction percentage

The Effect of Catalyst to Acid Ratio on Nickel Extraction Under constant conditions in the form of temperature of 80 °C, time of 2hr, particle size of 200 mesh and stirring speed of 100 rpm, the results are obtained as shown in the following diagram.

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Effect of solid:liquid ratio on persentage conversion

100

80 H2SO4 HNO3 60 Hcl 40 Aqua regia 20 conversion%

0 0.5 0.3 0.2 0.1 0.05 solid:liquid ratio

Figure 3. The effect of catalyst to acid ratio on nickel extraction percentage

The Effect of Catalyst to Acid Ratio on Tungsten Extraction Under constant conditions with a temperature of 80 °C, a time of 1hr, a particle size of 200 mesh and a stirring speed of 100 rpm, the results are obtained as follows.

Figure 4. The effect of catalyst to profit ratio on the percentage of tungsten extraction

Effect of Reaction Temperature on Nickel Extraction One of the most important parameters in nickel recovery is the reaction temperature. These experiments under constant conditions in the form of 2hr temperature, stirring speed of 100 rpm, particle size of 200 mesh, S/L equal to 1.2 and the results were obtained as shown in the following diagram. It was observed that the best reaction temperature for sulfuric acid 100 90, so it can be said that the optimum temperature for maximum nickel recovery is 100-90.

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Effect of temperature on percentage conversion

100 90 80 H2SO4 70 HNO3 60 Hcl 50 40 Aqua regia

30 conversion % 20 10 0 120 100 90 80 60 40 20 temperature,.C Figure 5. Figure of the effect of temperature on the percentage of nickel extraction

Effect of Reaction Temperature on Tungsten Extraction These experiments were considered in constant conditions in the form of 1hr time, particle size of 200 mesh and stirring speed of 100 and S/L ratio of 1.5 and the results were plotted as follows.

Effect of temprature on persentage conversion

90 80 70 60 NaOH 50 KOH 40 30

20 conversion% 10 0 100 90 80 60 40 20 Temperature,.C

Figure 6. Figure of the Effect of Temperature on the Percentage of Tungsten Extraction

The Effect of Catalyst Particle Size on Nickel Extraction These experiments were considered in constant conditions in the form of 80 °C temperature, 2 hr time and 100 rpm stirring speed and S/L ratio of 1.5. The results were plotted as follows.

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Effect of particle size on percentage conversion 150 H2SO4 100 HNO3 HCl Aqua regia 50

230 200 150 100 Conversion % Particle size Figure 7. Graph of the Effect of Particle Size on the Percentage of Nickel Extraction

The Effect of Catalyst Particle Size on Tungsten Extraction These experiments were considered in constant conditions in the form of 80 °C temperature, 2hr time and stirring speed of 100 rpm and a ratio of 1.5 times S/L and the results were plotted as follows.

Effect of particle size on percentage conversion

80 70 60 50 NaOH 40 KOH 30

20 % conversion% 10 0 230 200 150 100 particle size

Figure 8. Figure of the Effect of Particle Size on the Percentage of Tungsten Extraction

Effect of Leaching Solution Concentration on Nickel Extraction These experiments are considered in constant conditions in the form of temperature 80 °C, time 2hr, particle size 200 mesh and stirring speed 100 rpm, s/l ratio equal to 1.5 and the results are plotted as follows.

Figure 9. Figure of the effect of sulfuric acid concentration for nickel extraction

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In the case of hydrochloric acid, the maximum recovery rate was 37%. Also, in the case of Tizab Soltani, the highest recovery rate was in the range of 60% and in the case of nitric acid, the highest recovery rate was in the range of 60%.

Figure 10. Figure of the Effect of Hydrochloric Acid Concentration for Nickel Extraction

Figure 11. Effect of Soltani acid concentration effect for nickel extraction

Figure 12. Figure Showing the Effect of Nitric Acid Concentration for Nickel Extraction

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Effect of Leaching Solution Concentration on Tungsten Extraction These experiments were performed under constant conditions in the form of temperature of 80 °C, time of 2 hours, stirring speed of 100 rpm and solid to liquid ratio of 1.5 and mesh size of 200 and the results were plotted as follows.

Effect of cocentration on percentage conversion

50 NaOH

40 KOH % conversion 30

0 0.2 0.5 0.8 1 Concentration.M Figure 13. Open concentration effect diagram for tungsten extraction

Effect of Reaction Time on Nickel Extraction These experiments were performed under constant conditions in the form of temperature 80 °C, particle size of 200 mesh, stirring speed of 100 rpm and solid to liquid ratio of 1.5. And the results were obtained as a diagram below.

Effect of time on percentage conversion

120

100

H2SO4 80 HNO3 60 HCL

Aqua regia 40 % conversion 20

0 8 7 6 5 4 3 2 1 Time,hr

Figure 14. Time chart for nickel extraction

Effect of Reaction Time on Tungsten Extraction These experiments were performed under constant conditions in the form of temperature of 80 °C, particle size of 200 mesh, stirring speed of 100 rpm and solid to liquid ratio of 1.5 and the results were obtained as follows.

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Effect of time on percentage conversion

80 70 60 50 NAOH 40 KOH 30

20 % conversion% 10 0 4 3 2 1 Time,hr

Figure (15) Time effect diagram for tungsten extraction Conclusion Catalysts play an important role in various industrial processes and accelerate the reaction, improve product quality, reduce energy consumption and ultimately reduce the cost of a process. Catalysts in chemical reactions accelerate the reaction by reducing the activation energy, while they are not consumed in these reactions and can be recovered. Catalysts used in refineries, after several years of use, have their catalytic activity due to processes such as precipitation and deposition of materials. On the coking catalyst surface, heavy metal deposits in the crude oil lose their toxicity, aging and deformation due to high temperatures. These catalysts, which cannot be used at this stage, are hereinafter referred to as used catalysts. In this case, the used catalysts are discharged as waste. Disposal of these catalysts, which contain significant amounts of heavy metals, is environmentally hazardous. This study investigates the possibility of recovering nickel and tungsten from used catalysts (Ni/W) in the hydrocracking unit of Isfahan Oil Refinery. In the two-step recovery process, nickel is first recovered as a sulfate solution by sulfuric acid, nitric acid, hydrochloric acid and acidic acid as the extracting acid, and the parameters affecting the recovery time the reaction acid, the particle size and the stirring speed of the reaction mixture were investigated. After determining the optimal conditions for the nickel recovery process, based on the results shown in the table below, the best acid for nickel extraction under the specified conditions is Soltani acid with a recovery of 98.02%. The final product obtained is nickel oxide particles, which is obtained by a two-step process of

143 precipitation by sodium hydroxide and calcination at a temperature of 700-650 °C. Then, in the second stage of recovery, the remaining used catalyst from the first stage is exposed to bases such as sodium hydroxide and potassium hydroxide and the existing tungsten is recovered as a brown solution of sodium tungstate (Na2WO4) and the parameters affecting the recovery of nickel, such as nickel concentration. The reaction temperature and time, the ratio of solid catalyst to acid consumption, particle size and stirring speed of the reaction mixture are investigated. The best yield for tungsten extraction under optimal conditions is sodium hydroxide with recovery of 76.7%. The final product obtained is tungsten oxide particles, which is obtained by a two-step process of precipitation by hydrochloric acid and calcination at a temperature of 650-600 °C.

Figures and Tables

Figure 1. Used Tungsten Nickel Natalyst

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Winning the third place in the level of bronze statue in the fifth, sixth and seventh national festival of the system of proposals 2014-2016

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Research in the oil refining industry is for the purpose of research and study to achieve knowledge and production of science, and what should be considered in research and development units is to conduct basic and scientific research and apply them in the production of a product and use It is a product at a larger level and ultimately performance optimization. Today, we need the right platform to sell new ideas and become a global scientific reference. One of the policies to increase the production centers of science and also the production of science in the sectors of the oil industry can be to create suitable bases for acquiring new technology. Of course, in the field of technology transfer and training of human resources, according to studies, technology transfer is not practical without the presence of specialized human resources and the quality of technology transfer depends on the knowledge and skills of human resources. The current approach of the oil refining industry is knowledge-based and technology-oriented, and due to the serious demand in the oil industry, it is worthwhile for scientific and research environments to move in line with the needs of the oil refining industry. Research and development in the oil refining industry as a driver of industrial, economic and social development is doubly important and a priority. Given the importance of the refining sector in industry and the need to update and use new technologies in this field, it is necessary for academic research as an auxiliary arm alongside industry. According to the mentioned materials, in the present book, a part of the researches done in the oil refining industry is mentioned. The Research and Development Unit of Isfahan Oil Refining Company is ready to cooperate with international researchers, scientists, professors and students in all fields of research. The ways to contact the R&D department are as follows:

Website: WWW.EORC.IR Email: [email protected]

Director of Research and Technology

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