V.S.B.Engineering College, Karur Department of Chemical Engineering

V.S.B.ENGINEERING COLLEGE, KARUR DEPARTMENT OF CHEMICAL ENGINEERING

CH8201 PRINCIPLES OF CHEMICAL ENGINEERING QUESTION AND QUESTION BANK PART A

NAME : BRANCH : ROLL NO. :

Prepared by Department of Chemical Engineering V. S.B. Engineering College, Karur

CH8201 PRINCIPLES OF CHEMICAL ENGINEERING Unit-1

1. Define: Chemical Engineering. It is the study and practice of transforming substances at a large scale/quantity for the commercial production for the real use and improvement of human beings. Such industrial application we can see in transformation of natural or waste substances to useful substances or energy in the field of chemical, petroleum, pharmaceutical, electronics & energy production industries.

2. Define: Chemical Engineer. Chemical engineers "develop economic ways of using materials and energy". Chemical engineers use chemistry and engineering to turn raw materials into usable products, such as medicine, petrochemicals and plastics on a large-scale, industrial setting. They may be involved in designing and constructing plants as a project engineer in selecting optimal production methods and plant equipment to minimize costs and maximize safety and profitability.

3. Draw the Chemical Engineering Tree.

4. Write about the first Chemical Engineer. George Edward Davis (1850–1907) is regarded as the founding father of the discipline of Chemical Engineering. The first Chemical Engineering course was given at the University of Manchester in 1887 by George E. Davis, who is said as the father of Chemical Engineering and the first Chemical Engineer. The 12 lecture series of Davis formed the Handbook of Chemical Engineering. The fundamental similarities observed in different processes in various plants led to the concept of unit operations involving physical phenomena in chemical process technologies. 2

5. What are the major roles played by Chemical Engineers to the world?/ List out the role of chemical engineers. (April-May 2018) The chemical engineer creates and develops manufacturing processes dedicated to the production of goods, to chemical transformations as well as to equipment for those processes. Product development, Process development with economic evaluation Monitor & optimize the production performance while minimizing the production cost in a cleaner and safer plant Their role is crucial in many sectors of the chemical, pharmaceutical, biotechnology, plastic, petrochemical and food industry. Some examples,

6. Explore your view on using chemical engineering in everyday life. After waking up brushing teeth. The toothpaste you used is manufactured by chemical engineer. The gas burner where LPG is burning is a product of petrochemical industry Dye or color of dresses, shoes (product of tanning process) are results of chemical engineering. Powder, perfume, nail polish so on are made by chemical engineers The fuel which drives bike / car is a product chemical engineering. LCD TV, laptop (chips manufacturing), photocopier (ink), photography (chemicals) are all the products of chemical engineering. Medicines, antibiotics are products of chemical engineering, Preparation and use of processed food (ice-cream, chocolates, cold drinks) involve chemical Engineering

7. Expand: AIChE, MIT. American Institute of Chemical Engineers (AIChE) Massachusetts Institute of Technology (MIT)

8. Write about COURSE ‘X’ (Course ‘Ten’). In 1888, a series of lectures about British chemical industry operating practices presented by George E. Davis at Manchester Technical School in the UK, and it spread to German universities Influenced by developments MIT chemistry professor Lewis M. Norton created Course X, the world’s first four-year chemical engineering curriculum. Lewis Norton developed the Massachusetts Institute of Technology's “Course X,” which combined mechanical engineering with industrial chemistry, 1888 The first chemical engineering curriculum at MIT was offered in 1888 and helped to establish chemical engineering as a discipline. Combining mechanical engineering with industrial chemistry, Course X was designed, according to a contemporary course catalog, “to meet the needs of students who 3

desire a general training in mechanical engineering, and at the same time to devote a portion of their time to the study of the applications of chemistry to the arts, especially to those engineering problems which relate to the use and manufacture of chemical products.”

9. Name four achievements of Chemical Engineering. Drinking or potable water Petrol or gasoline (and other fuels including diesel) Antibiotics Plastics

10. Name eminent personalities of chemical engineering. George Edward Davis, Arthur D. Little, John. H Perry, Robert Samuel Langer Jr.,Thomas H. Chilton, Elmer L. Gaden Jr., Carl Bosch & Fritz Haber, Margaret Hutchinson Roussan, Vladimir Haensel

11. Write on some major chemical products and their uses in daily life Sl. Common name Molecular formula Use No.

1. Baking Powder NaHCO3 Cooking

2. Soap/Detergent Ester/Alkylbenzene sulphate Cleaning

3. Toothpaste CaCO3, Na2F Teeth & gum care

4. Salt NaCl Cooking

5. Vinegar CH3COOH Food preservation, additive, Taste

6. Bleaching Powder NaOCL Cleaning, pest removal

7. Aspirin C9H8O4 Medicine

8. Caustic Soda NaOH Cleaning, Catalysis

9. Fertilizer (synthetic) Ca(HPO4)2, Nitrogen & Food production phosphate salts

10. Pesticide or Organochloring, Food production Agrochemicals organophosphates, carbamates, DDT

11. Synthetic fibre, Cellulose Actate Clothing textiles

12. Dye Coloring of cloth

13. Polymer coat, paint Sheltering, lifestyle, wall coloring

12. What is chemical process Industries? Give example (April- May 2018) Chemical process industries are those where the raw materials undergo chemical conversion or physical conversions during their processing to finished products. Eg. Petrochemical Industry, Polymer, dye and Paint manufacturing Industries.

13. What is heavy chemical process Industries? Give example Produces simple compounds from locally available large amount of raw materials. Usually they are very large industries and the products purified to such an extent that they could be used as raw material for other industries (directly marketable). Large quantity production in large industries to produce crude/less pure product. eg: NaOH, Na2CO3, Mineral Acid.

14. What is fine chemical process Industries? Give example Products are speciality chemical & are produced in small quantity with very high purity as finished goods. eg: Special solvents, medicines, organic acids (Acetone, Acetonitrile).

15. How chemical Industries could be classified based based on composition of produced chemicals? Give example i) Organic Chemicals: products are having organic carbon atoms in molecules. Eg: hydrocarbons, phenol, organic acids ii) Inorganic Chemicals: products are having no organic carbon atoms in molecules. Eg: NaOH,

K2Cr2O7 iii) Polymers: products are having big macromolecular structure formed by covalent bondings. Eg: polystyrene (rubber), Poly vinyl chloride

16. How chemical Industries could be classified based based on availability of raw material? Give example i) Natural: products are processed after being naturally extracted. eg: coal, petrol, natural gas

ii) Synthetic Chemicals: products are entirely man-made and not naturally extracted. Eg: NaOH,

K2Cr2O7 , Poly vinyl chloride

16. How chemical Industries could be classified based based on application of products? Give example i) Catalyst: products are used as catalyst in different process industries. Eg: AlCl3, MnO2, platinum

ii) Drug/Medicines: products are used for medicinal purposes. Eg: Paracetamol, pantafol iii) Resin: products are used as cation or anion exchange purposes. Eg: urea formaldehyde, epoxy resin, polyester iv) Dye: products are used as coloring agent or pigments. Eg: Methyle red 5

v) Solvent: products are used as solvents of chemical reactions. Eg: benzene, ethanol, di methyle

formamide (DMF) vi) Food production: fertilizer, pesticides vii) Miscellaneous: glass, cement etc.

17. What is Chemistry?

The branch of science concerned with the substances of which matter is composed, the investigation of their properties & reaction & the use of such reactions to form new substances is chemistry.

18. What is Chemical Technology? It is the study of organic or inorganic chemistry, industrial & physical chemistry, quantitative & instrumental analysis & chemistry related to oil, gas, agricultural, food & environmental sectors, chemical technologists provide technical support to the people in chemical related fields, to set up labs & to conduct chemical experiments under the guidance & supervision of Chemical Engineer.

19. How chemistry and chemical engineering are different from each other? a) The main difference in Chemical Engineering and Chemistry is the scale of application. People of chemistry generally carryout experiments in labs and report on the development of a new chemical. But, to bring the small lab scale production to industrial scale, Chemical Engineers are required. b) Chemistry is mostly focused on reaction & testing of chemicals but Chemical Engineering is focused on production, product development, in-depth design of process technology & reactor design. Side- by-side a chemical engineer needs to have a good knowledge on process economics so that the cost of developed product could be lessened.. c) Education is also one key issue. Chemistry deals with reaction, reaction kinetics with basic or advanced theoretical approaches. Chemical Engineers study the advanced courses of application oriented courses of Physical Chemistry, Biochemistry, Polymer or Organic Chemistry with subjects of deep knowledge of heat transfer, mass transfer, fluid mechanics, bioprocessing and reactor design. d) Chemistry Product development by reaching in lab, testing of product. Chemical Engineering Process development, reactor design for production in industrial scale.

19. How chemical engineering and Chemical Technology are different from each other? Education is the key issue. Chemical Engineers study the advanced courses of application oriented courses of Physical Chemistry, Biochemistry, Polymer or Organic Chemistry with subjects of deep knowledge of heat transfer, mass transfer, fluid mechanics, bioprocessing and reactor design. Chemical technologists study General Chemistry, Physics, Instrumentation & Analytical analysis of Chemistry.

Chemical Engineering Process development, reactor design for production in industrial scale. Chemical Technology Assist, monitor, maintain Lab/industry under the supervision of Chemical Engineer.

20. Give an example to show the differences in works of a chemist, chemical engineer and chemical technologist. Let’s assume, a Chemical Engineer has developed a new eco-friendly product/ medicine in the Lab. After development he will send the product to Chemistry (Chemistry) for qualitative (how good is the product) & quantitative (how much quantity/concentration) analysis.

After receiving the report of analysis, the engineer will aim to generate the product in industrial scale. This is called Technology Transfer, by design & development of production Technology. Now, Chemical Technologists monitor the labs, perform the trials, take care of instruments, program the machines, make sure they are performing well enough; under the guidance & supervision of the Chemical Engineers.

Unit-2

1. What is the role of mathematics in chemical engineering?

 Knowledge of mathematics (linear/non linear/complex algebra, polynomial, exponential, calculus) is a must for chemical engineers to represent a physical systems characteristics and transport processes into the respective mathematical expressions.  During the mathematical analysis of transport of mass/momentum/energy we develop some equations to represent the phenomenon occurring inside the systems. These are called mathematical model equations.  As Chemical Engineering is mostly developed on concepts of physics and mathematics is an integral part of physics; chemical engineers need to have a sound knowledge of mathematics for the development and solving of performance equations.  Mathematics is an useful tool to calculate how much mass/energy/momentum is coming into a system or going out, subjected to a specific set of operating conditions.

2. Write in short about role of physics in chemical engineering.

 Physics is the eye to see the true existence of nature and physical phenomenon to explain all micro and macro level scenario. Chemical Engineers need to deal with very fine charged particles and ionized gases. When there is flow of charged particles, or electron flow, there is flow of current or electricity. By the generation of electric field, there would be generation of magnetic field.  Chemical Engineers need to deal with thermodynamics which is dealing with relationships between heat and all other forms of energy (mechanical, electrical or chemical energy) which is driven by the fundamental principles of physics. For any physical system, the three laws of conservation of mass, momentum and energy should be obeyed to analyze the specific physical or chemical reacting systems.

3. What is the role of chemistry in chemical engineering?

 Industrial Chemistry plays a major role in providing proper direction to the chemical engineers. The existing plants, production processes of commercial chemicals, equipment design, the raw materials required to get desired product, use and development of catalyst, intensification of reaction by the use of catalyst, are the knowledge which is provided by the subjects like basic and industrial chemistry.  The concepts of reactor design for a specific chemical reaction, the type of reaction (endothermic or exothermic) by the use of a specific catalyst, the reaction thermodynamics are derived from the concepts of chemistry which are highly applicable in chemical engineering.  The concept of molecular weight, equivalent weight, concentration, molecular and atomic mass, the proper balancing of reactions for industrial applications are derived from the concept of chemical Stoichiometry.  For preparation of stock solution or a dilute solution, for any acid/base solution or to conduct, any acid/base reaction, concept of chemistry is very necessary to be applied in Chemical Engineering fields, because of the use of units like molarity (M), normality is widely done.

4. Write in short about role of biology in chemical engineering.

 As Chemical Engineering is basically the industrial production of commodity chemicals, a lot of process technologies are present which involve biological species like microbes and other living species.  To handle the microbes and to produce/extract organic acids/proteins from the cells proper knowledge of industrial biotechnology is required to control the upstream or production process. Chemical engineering could get involved in the downstream purification of the product to maintain and increase the product purity or quality.  Different types of proteins, vaccines, immunity growing drugs and medicines are developed from the integration of chemical engineering and bioprocess and pharmaceutical engineering technologies.  Development of Biomedical engineering as a separate educational stream is fostering the growth of industrial production of life saving drugs. But the industrial productions of Biotechnology / Biochemical / pharmaceutical / bioprocess engineering are based on Chemical Engineering principles.

5. Write Zeroth law of thermodynamics.

Zeroth Law of Thermodynamics: If two thermodynamic systems each are in thermal equilibrium with the third one, then they are in thermal equilibrium with each other.

A Thermal Thermal Equilibrium Equilibrium

B C Thermal Equilibrium

6. Write first law of thermodynamics.

First Law of Thermodynamics: Also known as the conservation of energy which states energy can neither be created nor destroyed. It only changes from one form to the other. Change in internal energy = E = heat flow across the boundary - work done by the system = q - w

7. Write second law of thermodynamics.

Second law of thermodynamics: Entropy (randomness of an isolated system never decreases but always increases, simply we can say the entropy of universe (ultimate isolated system) only increases and never decreases. dQ 0 T

Entropy 0

8. Write third law of thermodynamics.

Third law of Thermodynamics: Entropy of system reaches a constant value as the temperature reaches absolute zero. The entropy of a system at absolute zero (0K or -273.150C) is typically zero.

9. Define: internal energy. Every system has a certain amount of energy within itself. This is known as internal energy. Internal Energy is nothing but the sum of all the microscopic forms of energy.

10. What is meant by enthalpy? The sum of the internal energy and the work done, or the amount of energy within the system (or the substance) that is available for conversion into heat.

11. Write the concept of entropy. Entropy is a thermodynamic property and state function. It is a measure of the randomness of a system or disorder in the system.

12. What is meant by heat capacity? The amount of heat input required to raise the temperature of temperature of 1 mol the substance by 1K.

13. What are the concepts that could be derived from first law of thermodynamics?/ What are the postulates of first law of thermodynamics a) Concept of Internal Energy b) Conservation of energy

14. Write the Clausius statement It is not possible to construct any device which could convey heat from a low temperature region to a high temperature region without the help of any external agency.

15. What are the limitations of first law of thermodynamics? The first law of thermodynamics is a law of conservation of energy.  It does not specify the direction of the process. All spontaneous processes is processed in one direction only.  The first law of thermodynamics does not deny the feasibility of a process reversing itself.  It does not specify to what extent the process proceeds.  It does not state whether complete conversion of internal energy to work is possible or not

16. Define: system and surroundings. System is the quantity of matter or a region in space upon which attention is concentrated during the analysis of a problem. Surrounding is the region or area external to a system.

17. Define: extensive property and intensive property The properties dependent upon the extent or quantity of the mass of a system is known as extensive property. Eg: mass, volume etc. An intensive property is a property of matter that depends on only the type of matter in the system and not on the amount. Eg: temperature, solubility etc.

18. What is meant by adiabatic process? 10

An adiabatic process is one that occurs without transfer of heat or mass of substances between thermodynamic system and its surroundings. In an adiabatic process energy is transferred to the surroundings only as work.

19. What is meant by analogy in transport phenomena?

 Transport phenomena is the unified description of heat, mass, momentum transfer, their analogy and dependence on each other during a practical problem. Transport phenomena brings deep mathematical connections and frameworks among all the transfer processes.  For a practical R & D or industrial process involve fluid flow inside a reactor to carry out reaction, which could be endo or exothermic in nature. For those situations, heat transfer, mass transfer, fluid mechanics and if required reactor design/reaction kinetic knowledge is necessary.  The basic transfer equations could be used for more difficult purposes to solve/model such cases containing multiple transport processes in a single system.

20. Write the analogy between momentum transfer, mass transfer and heat transfer.

By following the basic transport equations, we can note an analogy among them:

For all cases, flux is directly proportional V I  to gradient These are also analogous to ohm’s law = R .

So, flux = constant × gradient. Potential Or, Rate of Flow = Resistance .

Fluid Mechanics / Momentum Heat Transfer Mass Transfer Transfer

dT QKA dx dCA du JDA AB τ = - μ Q dT dx dy Or qK   A dx

constant = Thermal conductivity constant = Diffusivity constant = viscosity (thermal diffusivity) (mass diffusivity) (momentum diffusivity)

dT dC du Potential= Potential = A Potential = dx dx dy

Resistance= - 1/KA Resistance= - 1/DAB Resistance= - 1/µ

21. What is meant by Reynolds number? Reynolds number is the ratio of inertial forces to viscous forces within a fluid. It is a dimensionless number used in fluid mechanics to indicate whether fluid flow past a body or in a duct is laminar or turbulent. It is expressed by:

 D Re   Where, ρ is the density of the fluid υ is the velocity of the fluid with respect to the object μ is the dynamic viscosity of the fluid D is the characteristic linear dimension

22. Define: laminar flow and turbulent flow. Laminar flow occurs at low Reynolds numbers (<2100) where viscous forces are dominant and is characterized by smooth constant fluid motion. Turbulent flow occurs at high Reynolds number (>4200) and is dominated by inertial forces which tend to produce chaotic eddies, vortices and other flow instabilities.

23. Write Newton’s law of viscosity. Newton’s law of viscosity states that the shear stress between adjacent fluid layers is proportional to the velocity gradients between the two layers. The ratio of the shear stress to shear rate is a constant for a given temperature and pressure and is defined as the coefficient of viscosity. du  dy

du  dy Where,

τ is Shear stress = F/A μ Viscosity du/dy is the rate of shear deformation

24. Write Fourier’s law of heat conduction. dT Q=-KA dx Fourier’s Law of Heat conduction: Q dT or,q= =-K A dx Q is the total heat transferred (W), K is the material's conductivity (W·m−1·K−1), T is the temperature gradient (Kelvin), A is area of heat transfer area (m−2) and x denotes position (m).

25. Write Newton’s law of cooling. dq Newton’s Law of Cooling:  hA  T dt q is the thermal energy (Joule) and t denotes time (sec). h is the heat transfer coefficient, (W/(m2 K)) A is the heat transfer surface area (m2), T is the temperature (kelvin).

26. Write Stefan-Boltzmann law. Stefan- Boltzmann law states that the total radiant heat energy emitted from a surface is proportional to the fourth power of it’s absolute temperature. It applies to blackbodies and theoretical surfaces that absorb all incident heat radiation.

E= σT4 Where, E is the radiant heat energy emitted from a unit area in one second T is the absolute temperature σ is the Stefan-Boltzmann constant

27. Write Fick’s law of diffusion. dC Ficks Law of diffusion: J = - D A A dx

J is the diffusion flux, (mol m−2 s−1) or is amount of substance diffused per unit area per unit time. D is the diffusion

2 3 coefficient or diffusivity ( m /s.). CA is the concentration (mol/m .) and x is position (m).

28. Write mass conservation law. Mass can neither be created, nor be destroyed by any chemical reaction or physical process.

29. Write Newton’s second law. The law states that the acceleration (a) of an object is directly proportional to the net force (F) acting upon the object and inversely proportional to the mass (m) of the object. F= ma

30. Write law of energy conservation. Conservation of Energy: The total energy of an isolated system is constant. It can neither be created nor be destroyed.

31. What are the three modes of heat transfer? The three modes of heat transfer are conduction, convection and radiation.

32. Define any one mass transfer operation. Distillation is a mass transfer operation which is the method of separation of components from a liquid mixture which depends on the differences in boiling points of the individual components between a liquid and gas phase in the mixture.

33. What is Chemical kinetics/ reaction kinetics? (April-May 2018) It is the study to know rate of reaction or how fast a reaction proceeds. This is the base line from where the chemical reaction engineering is developed where the concept of thermodynamics and physical chemistry is integrated to design a chemical reactor for industrial production of chemicals.

34. Define: Homogeneous and Heterogeneous reactions. Homogeneous reactions are chemical reactions in which the reactants and products are in the same phase. Heterogeneous reactions have reactants in two or more phases. Reactions that take place on the surface of a catalyst of different phase are also heterogeneous.

35. Define: Catalytic and Non-catalytic reactions. The chemical reaction whose rate is influenced (accelerated or decelerated) by a catalyst is catalytic reaction. The catalyst participates in the intermediate stages of the reaction and is liberated quantitatively at the end of the reaction in a chemically unchanged form. Non- catalytic reaction does not involve the role of a catalyst.

36. Write the basic mathematical equation for reaction kinetics.

For a single phase reaction in an ideal reactor aA bB  rR  sS , the rate of reaction for reactant A is:

1 dNA moles of A disappearing -rA = - = v dt Volume of reactor . Time (-) minus sign signifies the disappearance or loss of A

37. Define: Exothermic and Endothermic reactions. Exothermic reaction is a chemical reaction that releases energy in the form of heat, light or sound. It may occur spontaneously and result in higher randomness or entropy of the system. They are denoted by negative heat flow and decrease in enthalpy. Eg: combustion Endothermic reaction is a chemical reaction that absorbs heat energy in order to proceed. Work must be done to get these reactions to occur. It is characterized by a positive heat flow and an increase in enthalpy (+ΔH) Eg: photosynthesis

38. Define: Reversible and irreversible reactions. In an irreversible reaction, the reactants react to form the products which cannot revert back to the reactants. Eg: Combustion. In reversible reactions, as the reactants react with other reactants to form products, the products further react with other products to form the reactants. Eg: Reaction of nitrogen and hydrogen to form ammonia in a closed system.

39. What is meant rate of chemical reaction? The rate of a chemical reaction may be defined as the rate of change of concentration of any reactant and any product with respect to time.

40. What are the factors affecting the rate of a reaction? The factors that affect the reaction rates are: a) Surface area of a solid reactant b) Concentration or pressure of a reactant c) Temperature d) Nature of reactants e) Presence or absence of catalyst

41. Write Arrhenius law. Arrhenius equation gives the dependence of the rate constant of a chemical reaction on the absolute temperature, a pre-exponential factor and other constants of the reaction. Activation energy of a reaction could be found by Arrhenius equation:-

E KAexp RT  .

K is the rate constant, T is the absolute temperature (kelvin), A is a constant for each chemical reaction. E is the activation energy for the reaction and R is the universal gas constant (8.314 J⋅mol−1⋅K−1).

42. Define: Elementary and Non Elementary Reactions. If the reaction is elementary, the exponents of the respective reactants in the rate expression are same as the corresponding stoichiometric coefficients of the reactants. If it differs then it is stated as non- elementary reaction.

43. Define: Molecularity of reaction. The sum of the stoichiometric coefficients of the respective reactants is known as molecularity of the reaction.

44. Write the methods used to analyze the kinetic data or rate data. a) Transition State theory b) Collision State Theory

45. Define: ideal reactor. The reactors in which every molecules of reactant spent equal amount of residence time is called ideal reactor. These are of three types: Batch reactor, CSTR and PFR.

46. Define: batch reactors. Batch reactors are ones in which desired amounts of reactants are fed to the reactor all at a time. Proper thermodynamic conditions like pressure and temperature are maintained. Appropriate provisions for heat addition or removal, stirring, temperature and pressure measurement and, control and viewing facilities are provided.

47. Define: CSTR. Continuous Stirred Tank Reactor (CSTR) is a continuous flow reactor consisting of a vessel with inflow and outflow piping arrangement. Perfectly mixed condition is assumed in the reacting mass everywhere in the reactor due to stirring effect. The reactor operates on steady state condition hence constant liquid level is maintained in the reactor.

48. Define: PFR. Plug flow reactors (PFR) operate on continuous mode and generally steady state condition is maintained. Its configuration is like a pipe. Reactant flows in at one end and the products and unconverted reactants are taken out continuously from the other end.

49. Define: non-ideal reactors. In actual practice ideal plug flow or complete mixing is highly improbable. The fluid element in the flow reactor may have different residence times which affect their individual degree of conversion. Such reactors are called non-ideal reactors. Some fluid elements may not escape the reactor at all and undergo maximum conversion, whereas some elements which find the shortest path to travel through the reactor suffer very low conversion.

50. What is meant by fixed bed reactor? A fixed bed reactor consists of a cylindrical vessel packed with catalyst pellets. Metal support grid and screen is placed near the bottom to support the catalyst. Inert ceramic balls are placed above the catalyst bed to distribute the feed evenly. Advantages of fixed bed reactor include ideal plug flow behavior, lower maintenance cost and reduced loss due to attrition and rear. Poor heat distribution leading to non-uniform reaction rate and plugging of bed resulting in high pressure drop of the bed are the major disadvantages of such reactors.

51. Define: tubular reactor. Tubular reactors operate on continuous mode and generally steady state condition is maintained. Its configuration is like a pipe. Reactant flows in at one end and the products and unconverted reactants are taken out continuously from the other end. Eg, PFR

52. Define: fluidized bed reactor. In fluidized bed reactor catalyst pellets of average size less than0.1 mm are fluidized by reactant fluid. The linear velocity is maintained above the minimum fluidization velocity required to obtain the fluidized bed. As the superficial velocity increases, the bed expands and becomes increasingly dilute. Uniform temperature distribution is the advantage of such reactor. However, extensive operational and maintenance cost and attrition and loss of catalyst due to fluidized condition are the major disadvantages.

53. What is meant by catalyst? Any substance which influences the rate of a chemical reaction but itself remains unchanged chemically at the end of the reaction is called a catalyst.

54. What are the types of catalysts? Catalyst are homogeneous or heterogeneous depending on whether the catalyst forms a single phase with the reactants or constitutes a separate phase.

55. What is meant by promoters (in catalysis)? An additive which has no catalytic property of its own but enhances the activity of a catalyst is called a promoter. For example, the catalytic activity of V2O5 in oxidation of SO2 is enhanced appreciably when sulphates of alkali metals are added in small amounts.

56. Define: inhibitors (in catalysis). The substances that are added during manufacture of the catalyst to reduce the activity is known as inhibitor. Eg: In ethylene oxidation, ethylene oxide is the desired product but complete oxidation gives CO2 and H2O which are undesired products.

57. Define: accelerators (in catalysis). The substances that act as diluents which shift the equilibrium composition in a favorable direction or afford better temperature control are accelerators. These substances may counteract coking or poisoning or improve selectivity by poisoning undesired side reactions.

58. What is meant by carriers/supports (in catalysis)? Carriers or support serve principally as a framework on which the catalyst is deposited.

59. Define the term ‘Catalyst Deactivation’. Deactivation is the declining in a catalyst’s activity as time progresses. This is caused by aging or by deposition of foreign material on the surface of catalyst.

60. What is meant error (in process control)? Error is defined as the difference between set-point and process variable.

61. Define: set point. The set-point is where the process variable is desired to be.

62. Draw the generalized process control system/ Draw the components of a simple process control system/ What are the components of a process control system Generalized diagram of a simple control system is as following:

Disturbance

+ Set Controller Final control element Process Output Point –

Measuring device The components are: set point, controller, final control element, process, disturbance, measuring device.

63. What is meant by closed loop system (in process control)? A closed loop system is referred as a feedback control system. These systems record the output instead of input and modify it according to the need. It generates preferred condition of the output as compared to the original one. It doesn’t encounter any external or internal disturbances.

64. What is meant by open loop system (in process control)? An open-loop control system takes input under the consideration and doesn’t react on the feedback to obtain the output. This is why it is also called a non-feedback control system. There are no disturbances or variations in this system and works on fix conditions.

65. Explain shortly Laplace Transform. Laplace transform is an integral transform that takes a function of a real variable t (often time) to a function of a complex variable s (complex frequency) If, the transfer function of a 1st order system is G t  eat at t  0

   Then, G S  L eat  G() t e  st dt  e  at e  st dt  e () s  a t dt   0   0    0 1  Sa

66. What are the types of controllers?

P controller, PI Controller, PID controller

67. What are the need/requirements of control systems?

We need control systems for needs like:

a) To suppress the influence of external disturbances b) To ensure the stability of a running process c) To optimize the performance of a chemical process.

68. What is the role of design in chemical engineering? What are the advantages of process dynamics, design and control? (April- May 2018)

In a Chemical Engineering plant there is arrangement of processing unit like reactors, heat exchangers, pumps, distillation, absorption columns, evaporators etc. in a rational manner and a systematic way. To operate the plant in a systematic way for maximum conversion of feed stock to products proper design of equipment and control strategies become necessary.

The advantages of analysis of process dynamics, design and control systems are:-

a) The help in improving the process economics for the production of desired product. b) To enhance the process safety by regulating temperature, pressure and concentration of product etc. c) To improve and maintain product quality (conc., purity etc.) from a chemical operation. d) To maintain the environmental regulations, like, release of toxic gas/waste water/ sludge etc., control systems are required to strictly follow the regulations. e) Operational constraints could be maintained by control systems like; a pump need to have its net positive function head, tanks should not go dry or overflow, distillation columns should not get flooded, catalyst bed should maintain an optimum temperature.

UNIT- III; Part A

1. Define unit operations and unit process. Unit operations: The operations which involve only physical operations and not chemical operations are referred as unit operations. eg.- Fluid flow, heat transfer, distillation, crushing, grinding and crystallization etc. Unit process: The processes where in a chemical reactor, reactions occur and reactants get converted to products are referred as unit processes. eg.- sulphonation, nitrification, esterification, alkylation etc.

2. Draw the chemical engineering tree.

3. Name four unit operations. Fluid flow, heat transfer, distillation, crushing, grinding and crystallization etc.

4. Name four unit processes. Sulphonation, nitrification, esterification, alkylation etc

5. Is combustion comes under unit process or unit operations? Justify. Combustion comes under unit process. Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen and carbon which produces smoke (carbon-di-oxide) in gaseous form. This is why, combustion is an unit process.

C+O2 CO2

6. Define calcination reaction. Calcination means a thermal treatment process in the absence of air or oxygen applied to solid materials to bring about a thermal decomposition.

CaCO3 CaO + CO2

7. Name the manufacturing processes of sulphuric acid production The manufacturing processes of sulphuric acid production are: lead chamber process and contact process

8. Name the unit operations involved in manufacture of sulfuric acid. Lead chamber process: fluid flow (flow of feed and product) and absorption Contact process: fluid flow (flow of feed and product) and absorption

9. Give the details of the reactions/ unit processes involved in lead chamber process for manufacturing of sulfuric acid. Lead chamber process: Potassium Nitrate (salt peter) was used as an oxidizing agent to oxidize sulpher to sulpher trioxide.

This used to be absorbed in water to produce H2SO4.

6KNO3 S  7 S  3 K 2 S  4 SO 3  6 NO

4SO3 4 H 2 O 4 H 2 SO 4 .

Lead chamber process with recycle of NO:

4NO O2  2 H 2 O  4 HNO 2

4HNO2 2 SO 2  2 H 2 SO 4  4 NO

10. Give details of reactions/ unit processes involved in contact process for manufacturing of sulfuric acid. Contact process and double contact double absorption process use the same chemical reactions:

S+O2 SO2

2SO2+O2 2SO3 using palladium catalyst 2SO + (H O + H SO )  concentrated H SO 3 2 2 4 2 4 (dil. H24 SO )

11. Name the manufacturing processes of soda ash production

The manufacturing processes of soda ash (Na2CO3) production are: Le-blanc Process and Solvay Process

12. Name the unit operations involved in manufacture of soda ash. Le-blanc Process: fluid flow (flow of feed and product), evaporation and filtration Solvay process: fluid flow (flow of feed and product), absorption, evaporation and filtration

13. Give the details of reactions/ unit processes involved in manufacture of soda ash by Le- blanc Process. First, sodium chloride was treated with sulphuric acid to yield sodium sulphate and hydrogen chloride in gaseous state.

22NaCl H2 SO 4  Na 2 SO 4  HCl

Sodium sulphate thus produced was blended with crushed limestone (CaCO3) and Coal (Carbon). This mixture was burnt to produce calcium sulphide and sodium carbonate.

Na2 SO 4 CaCO 3  Na 2 CO 3 2 CO 2  CaS

14. Give the details of reactions/ unit processes involved in manufacture of soda ash by Solvay process. Calcium Carbonate was heated to form Calcium oxide

CaCO32 CaO CO

At top of the tower, a concentrated solution of Sodium Chloride and ammonia is fed. As the carbon- di-oxide bubbles up through the liquid in counter current mode, sodium bicarbonate forms and precipitates out.

NaCl NH3  CO 2  H 2 O  NaHCO 3  NH 4 Cl

Ammonia was regenerated from the byproduct ammonium chloride by treating it with lime (calcium hydroxide) left over from CO2 generation.

CaO H2 O Ca OH 2

Ca OH2 2 NH4 Cl  CaCl 2  2 NH 3  2 H 2 O .

15. Write a note on Le-blanc Process. In 1791, French chemist Nicolas Leblanc patented this process. First sodium chloride was treated with sulphuric acid to yield sodium sulphate and hydrogen chloride in gaseous state.

Sodium sulphate thus produced was blended with crushed limestone (CaCO3) and Coal (Carbon). This mixture was burnt to produce calcium sulphide and sodium carbonate.

This sodium carbonate was extracted using water and concentrated by evaporation.

16. Write a note on Solvay process. In 1861, Belgian Scientist Ernest Solvay developed this method to convert sodium chloride to sodium carbonate using ammonia. At the bottom of the tower Calcium Carbonate was heated to form Calcium oxide

CaCO32 CaO CO At top of the tower, a concentrated solution of Sodium Chloride and ammonia is fed. As the carbon-di-oxide bubbles up through the liquid in counter current mode, sodium bicarbonate forms and precipitates out.

NaCl NH3  CO 2  H 2 O  NaHCO 3  NH 4 Cl The sodium bicarbonate to sodium carbonate by heating with release of water and carbon-dioxide.

22NaHCO3 NaCO 3  H 2 O  CO 2 Ammonia was regenerated from the byproduct ammonium chloride by treating it with lime

(calcium hydroxide) left over from CO2 generation.

CaO H2 O Ca OH 2

Ca OH2 2 NH4 Cl  CaCl 2  2 NH 3  2 H 2 O .

17. What is meant by modified Solvay process? The most important is the dual salt process (modified Solvay process) wherein ammonium chloride and sodium carbonate are produced simultaneously using common salt and anhydrous ammonia as the principal starting materials.

NH3 + H2O + CO2 NH4HCO3

NH4HCO3 + NaCl NaHCO3 + NH4Cl

18. How sodium carbonate is extracted from natural deposits?

Trona, trisodium hydrogendicarbonate dihydrate (Na3HCO3CO3·2H2O), is mined in several areas of the US and Turkey. In early 19th century several "halophyte" (salt-tolerant) plant species and seaweed species used to be processed to yield an impure form of sodium carbonate. The land plants (typically glassworts or saltworts) or the seaweed (typically Fucus species) were harvested, dried, and burned. The ashes were then washed with water to form an alkali solution. This solution was boiled dry to create the final product, which was termed "soda ash".

19. Name the catalyst used in manufacture of sulfuric acid. What are the advantages of it?

In contact process of sulphuric acid production, Vanadium Pentoxide (V2O5) was found to be effective in direct conversion of SO2 to SO3. Sulpher is oxidized to SO3 in a burner which is further converted to SO3 using V2O5 catalyst pellets in an exothermic reaction at a pressure of 20 atm.

20. Write the combustion (burning) reaction involved in manufacture of sulphuric acid. In contact process, sulpher used to be burnt in presence of oxygen to produce sulpher di oxide. Which is further oxidized to form sulpher trioxide in presence of vanadium pentoxide catalyst.

S O SO 22 22SO2 O 2 SO 3

21. Write the overall reaction of soda ash formation by Le-blanc process and solvey process. Le-blanc: First sodium chloride was treated with sulphuric acid to yield sodium sulphate and hydrogen chloride in gaseous state.

22NaCl H SO  Na SO  HCl 2 4 2 4

Sodium sulphate thus produced was blended with crushed limestone (CaCO3) and Coal (Carbon). This mixture was burnt to produce calcium sulphide and sodium carbonate.

Na SO CaCO  Na CO 2 CO  CaS 2 4 3 2 3 2 This sodium carbonate was extracted using water and concentrated by evaporation.

Solvay Process: At the bottom of the tower Calcium Carbonate was heated to form Calcium oxide

CaCO CaO CO 32 At top of the tower, a concentrated solution of Sodium Chloride and ammonia is fed. As the carbon- di-oxide bubbles up through the liquid in counter current mode, sodium bicarbonate forms and precipitates out. NaCl NH  CO  H O  NaHCO  NH Cl 3 2 2 3 4 The sodium bicarbonate to sodium carbonate by heating with release of water and carbon-dioxide. 22NaHCO NaCO  H O  CO 3 3 2 2 Ammonia was regenerated from the byproduct ammonium chloride by treating it with lime (calcium hydroxide) left over from CO2 generation. CaO H O Ca OH  2 2 Ca OH 2 NH Cl  CaCl  2 NH  2 H O 2 4 2 3 2 .

22. Write the main reactions involved in production of H2SO4 by lead chamber and contact process Lead Chamber Process: Potassium Nitrate (salt peter) was used as an oxidizing agent to oxidize sulpher to sulpher trioxide. This used to be absorbed in water to produce H2SO4. 6KNO S 7 S  3 K S  4 SO  6 NO 3  2 3 4SO 4 H O 4 H SO 3 2 2 4 . 12

Recycle of NO:

4NO O2  2 H 2 O  4 HNO 2

4HNO2 2 SO 2  2 H 2 SO 4  4 NO

Contact Process

S O22 SO 22SO O SO 2 2 3 SO3 dil.()() H 242 SO H O  H 24 SO  H 24243 SO  H SO SO

H2 SO 4( SO 3 ) H 2 O 2 H 2 SO 4

23. Why platinum is not recommended as catalyst in production of H2SO4. Primarily in the contact process, platinum was used. Though Platinum catalysts exhibit high activity but were costly and were easily deactivated by poisons such as arsenic trioxide (As2O3). Some of the arsenic impurities in the sulphur feedstock and that’s why the chance of deactivation is higher for arsenic. This is why it was replaced by vanadium(V) oxide (V2O5).

24. What is Flowsheet Representation of Process Plant? A flowsheet is a part of chemical process design where sufficient information of all the processes and operations are provided in a schematic diagram. For a basic bioprocess system, the block diagram is like following:

25. What are the types of Flowsheet Representation? The types of flowsheet are: a) Block diagram b) Simplified Engineering Flow-sheets c) Detailed Design Flow Sheets

26. What is meant by block diagram? Block diagram: Simple rectangular box diagrams which give a graphic layout of various steps in a process. Eg.: For a basic bioprocess system, the block diagram is like following:

27. What is meant by Simplified Engineering Flow-sheets? Simplified Engineering Flow-sheets: Visualization of a process in terms of possible physical shape of equipment (symbolic), stream quantities, material and energy balances, instrumentation details and other auxiliary requirements.

28. What is meant by Detailed Design Flow Sheets? A detailed design flow sheet of complete plant design is the combination of intricate and detailed flow sheets, specifications and details of equipments, detailed piping and electrical layout and plant layout etc.

29. Draw the simple block diagram of manufacture of soda ash by le-blanc process.

29. Draw the flowsheet for manufacture of soda ash by le-blanc process.

30. Draw the simple block diagram of manufacture of H2SO4 by lead chamber process.

31. Draw the simple block diagram of manufacture of H2SO4 by contact process.

32. Draw the simple schematic diagram of manufacture of H2SO4 by double contact double absorption process.

33. What is meant by chemical process equipment design? Chemical process equipment design is a part of overall process design where emphasize is provided to design individual equipments in a process. Proper design of process equipments is the platform for operation of unit processes to produce high-quality, cost effective design end-product. The design of equipment play a major role in industrial competitions. By the proper design and choice of such equipment, process safety and cost effective production both could be ensured.

34. What are the aspects/ considerations of chemical process equipment design? Some of the few things which should be considered while equipment design are: a) Material of Construction (MOC) b) Precaution in design and construction c) Pressure Vessels design d) Heat Transfer Equipment design e) Electrical Equipments design f) Rotating Equipments design g) Use of Pressure relief devices like Valves.

35. Draw the schematic diagram of an agitator.

36. What is agitator and why it is used?

The unit operation is used to prepare liquid–mixture by bringing in contact two liquids in a mechanically agitated vessel or container. Agitation refers to the induced motion of liquid in some defined may, usually in circulatory pattern and is achieved by some mechanical device. Agitation is required as it

 Dispenses a liquid which is immiscible with the other liquid by forming an emulsion or suspension of few drops,

 Suspends relatively lighter solid particles,

 Promotes heat transfer between the liquid in the think or container and a coil or jacket surrounding the container,

 Blends miscible liquids

37. Explain the process of dialysis and its use.

In medicine, dialysis is the process of removing excess water, solutes, and toxins from the blood in people whose kidneys can no longer perform these functions naturally. This is referred to as renal replacement therapy.

Dialysis works on the principles of the diffusion of solutes and ultrafiltration of fluid across a semi-permeable membrane. A semipermeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus. The counter-current flow of the blood and dialysate maximizes the concentration 8 gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood. The concentrations of solutes normally found in the urine (for example potassium, phosphorus and urea) are undesirably high in the blood, but low or absent in the dialysis solution, and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood.

38. Draw the schematic representation of dialysis process.

39.What are the different types of impellers?

Two types of impellers: Radial flow impellers (flow is induced in radial or tangential directions) and Axial flow impellers (currents are parallel to the axis of impeller shaft)

40. Illustrate different types of impellers.

42. What is open pan evaporator? Write the working principle with schematic diagram.

The Pan Evaporator set-up is designed to study the fundamentals of evaporation process. The set-up consists of a jacketed pan evaporator made of stainless steel and an electrically heated steam generator of suitable capacity. To evaporate the solution in pan, steam is allowed to enter in the jacket using a control valve. Condensate is collected from steam trap for energy measurement.

43. How the vacuum dryer works?/ What is vacuum dryer?/ Write the working principle of vacuum dryer with diagram.

Vacuum drying is the mass transfer operation in which the moisture present in a substance, usually a wet solid, is removed by means of creating a vacuum. Vacuum drying is generally used for the drying of substances which are hygroscopic and heat sensitive, and is based on the principle of creating a vacuum to decrease the chamber pressure below the vapor pressure of the water, causing it to boil. With the help of vacuum pumps, the pressure is reduced around the substance to be dried. This decreases the boiling point of water inside that product and thereby increases the rate of evaporation significantly. The result is a significantly increased drying rate of the product. The pressure maintained in vacuum drying is generally 0.03–0.06 atm and the boiling point of water is 25-30 °C.

44. What is the use of vacuum dryer?

In chemical processing industries like food processing, pharmacology, agriculture, and textiles, drying is an essential unit operation to remove moisture. Vacuum dryer can be used to dry heat sensitive hygroscopic and toxic materials. If the feed for drying is a solution, it can be dried using vacuum dryer as the solvent can be recovered by condensation.

45. How the spray dryer works?/ What is spray dryer?/ Write the working principle of spray dryer with diagram

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used. All spray dryers use some type of atomizer or spray nozzle to disperse the liquid or slurry into a controlled drop size spray. A spray dryer takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporized. Solids form as moisture quickly leaves the droplets.

46. What is the use/application of spray dryer?

Applications:

Food: milk powder, coffee, tea, eggs, cereal, spices, flavorings, blood, starch and starch derivatives, vitamins, enzymes, stevia, nutracutical, colourings, animal feed, etc.

Pharmaceutical: antibiotics, medical ingredients, additives

Industrial: paint pigments, ceramic materials, catalyst supports, microalgae

47.Write a note on grinding operation/ ball mill.

Grinding is performed to get grinded, blended very fine powdery particles by the principles of impact and attrition.

eg:- Ball mill. It’s a hollow cylindrical shell rotating about an axis and partially filled with steel balls. As it rotates about the axis, the material of higher diameter breaks by the impact of heavy steel balls and turn like powder.

48. Write the applications of a ball mill/ grinding machine.

The ball mill is used for grinding materials such as coal, pigments, and feldspar for pottery. Grinding can be carried out either wet or dry but the former is performed at low speed. Blending of explosives is an example of an application for rubber balls. For systems with multiple components, ball milling has been shown to be effective in increasing solid-state chemical reactivity. Additionally, ball milling has been shown effective for production of amorphous materials.

48. Write a short note on crushing operation/ jaw crusher.

Breaking down the size of large sized ones to smaller sized particles by the use of compressive force. eg.: Jaw crusher, where the crushing is performed in stages using a combination of a jaw, a cone and impact crusher. One jaw is stationary and the other jaw swings front and back due to the rotation of the eccentric. These combined motions compress and push the material through the crushing chamber at a predetermined size.

49. Write the applications of a crushing operation/ jaw crusher.

Jaw crushers are used for primary crushing of a wide variety of materials in the mining, iron and steel and pit and quarry industries. Furthermore they are used in recycling processes.

50. Write a short note on heat exchanger.

A heat exchanger is a device to transfer heat between two or more liquids. It could be used for both the purposes of heating and cooling, where the fluids are separated by a soil wall to avoid direct mixing. These are widely used in industries for space heating, refrigeration, air conditioning, power plants and chemical plants etc.

Such equipment employ both the principles of fluid mechanics and heat transfer.

The temperature drop in hot fluid = the temperature gain by cold fluid

Or, hh Ah (T h,in-T h,o) = hc Ac (T c,in - T c,o)

51. What are the types of heat exchangers?

Based on flow pattern of hot and cold fluid, heat exchangers could broadly classified in two types:

Based on the flow pattern of Hot and cold fluid, it could be classified as (a) parallel flow (where the cold and hot fluid flows are parallel or same to each other) and (b) counter current flow (where the cold and hot fluid flows are opposite to each other)

52. Show the schematic diagram of different types of heat exchangers with the temperature profiles.

53. Write a note on distillation./ what is distillation?

The unit operation where the separation is based on the boiling points of the constituents is called distillation. This is essentially a mass transfer operation where a mixture of two or more components boil. The vapor phase becomes richer in more volatile or ‘lighter’ components and liquid phase becomes richer in ‘heavier’ or less volatile components.

54. What is called relative volatility?/ Based on what the mixture is separated by distillation?

The separation of the mixture is based on relative volatility i.e. the component which is more volatile than the other, comes out first from the boiling mixture. For a liquid mixture of two components A and B, (called a binary mixture) at a given temperature and pressure, the relative volatility is defined as

yyAB/  AB  xxAB/

Where, yA is mole fraction of vapor phase of A, xA is mole fraction of liquid phase of A and 14 yB is mole fraction of vapor phase of B, xB is mole fraction of liquid phase of B

55. Draw the schematic diagram of distillation column.

56. Write a note on batch distillation./ what is batch distillation?

It refers to the use of distillation in batches, meaning that a mixture is distilled to separate it into its component fractions before the distillation still is again charged with more mixture and the process is repeated. Batch distillation has always been an important part of the production of seasonal, or low capacity and high-purity chemicals. It is a very frequent separation process in the pharmaceutical industry.

57. What is called relative volatility?/ Based on what the mixture is separated by distillation?

yyAB/  AB  xxAB/

Where, yA is mole fraction of vapor phase of A, xA is mole fraction of liquid phase of A and yB is mole fraction of vapor phase of B, xB is mole fraction of liquid phase of B

58. Draw the schematic diagram of a batch distillation column.

59. Describe the parts of a batch distillation column.

The simplest and most frequently used batch distillation configuration is the batch rectifier, including the alembic and pot still. The batch rectifier consists of a pot (or reboiler), rectifying column, a condenser, some means of splitting off a portion of the condensed vapour (distillate) as reflux, and one or more receivers. The pot is filled with liquid mixture and heated. Vapour flows upwards in the rectifying column and condenses at the top. Usually, the entire condensate is initially returned to the column as reflux.

60. Illustrate the schematic representation of crystallizer. (April-May 2018)

61. Explain the term unit process with example.

The processes where in a chemical reactor, reactions occur and reactants get converted to products are referred as unit processes. eg.- sulphonation, nitrification, esterification, alkylation etc.

62. What is unit operations? Give example.

The operations which involve only physical operations and not chemical operations are referred as unit operations. eg.- Fluid flow, heat transfer, distillation, crushing, grinding and crystallization etc.

63. Based on pore size how membranes are classified ?/ What are the names of different membrane separation techniques?

Microfiltration, ultrafiltration, nanofiltration, reverse osmosis, gas separation

64. Differentiate unit operations and unit process. (April-May 2018)

Unit operation Unit process

The operations which involve only physical The processes where in a chemical reactor, reactions operations and not chemical operations are referred occur and reactants get converted to products are as unit operations. referred as unit processes.

eg.- Fluid flow, heat transfer, distillation, crushing, eg.- sulphonation, nitrification, esterification, grinding and crystallization etc. alkylation etc.

65. What is membrane filtration?

A membrane is a thin layer of semi-permeable material that separates substances when a driving force/pressure is applied across the membrane. Membrane filtration through a very thin filter medium is also known as ‘surface filtration’. The solid particles to be separated are usually large compared to the pore size characteristic of the membrane. The pores on the surface are of irregular shapes.

The separation is based on physical size, charge or affinity or a combination of these properties. Large particles are rejected on the surface and do not accumulate on the surface and do not get a chance to enter into the interior of the filter.

66. Show the schematic representation of membrane filtration.

67. What is the pore size of microfiltration membranes and what is the applied pressure range?

Microfiltration membranes are having pore size of approximately 0.03 to 10 micron (1 micron = 0.0001 millimeter)

The operating pressure range is 0 to 4 bar.

68. What is the use of microfiltration membranes?

Materials removed by MF include sand, silt, clays, cysts, algae, and bacterial (microbes) species.

69. What is the pore size of ultrafiltration membranes and what is the applied pressure range?

Ultrafiltration has a pore size of approximately 0.002 to 0.1 microns (1 micron = 0.0001 millimeter)

The operating pressure range is 4 to 9 bar.

70. What is the use of ultrafiltration membranes?

Materials removed by UF include all the fat, oil, algae and microbes.

71. What is the pore size of nanofiltration membranes and what is the applied pressure range?

Nanofiltration has a pore size of approximately 0.001 microns (1 micron = 0.0001 millimeter)

The operating pressure range is 9 to 20 bar.

72. What is the use of nanofiltration membranes? 18

Materials removed by NF include selective removal of ions and salts along with all the fat, oil, algae and microbes.

71. What is the pore size of reverse osmosis membranes and what is the applied pressure range?

RO has a pore size lesser than 0.001 microns (1 micron = 0.0001 millimeter)

The operating pressure range is 15 to 40 bar.

72. What is the use of RO membranes?

Materials removed by NF include removal of ions and salts along with desalination and product polishing.

73. Write a note on crystallization Crystallization is an unit operation by which a solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Generally the crystals form by precipitation by freezing and deposition. Crystallization occurs in two major steps. The first is nucleation, the appearance of a crystalline phase from either a supercooled liquid or a supersaturated solvent. The second step is known as crystal growth, which is the increase in the size of particles and leads to a crystal state.

UNIT- IV; Part A

1. Write in short the role of computers in chemical engineering. Process design and application for Chemical Engineers through CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) Chemical engineering flowsheeting softwares like FLOWTRAN, ASPEN PLUS, PROCESS etc. are available by which steady state mass, energy balance, sizing and cost evaluation for a chemical process could be done Mathematical modeling and simulation using FORTRAN, MATLAB, PASCAL

2. Name any four chemical engineering software. Flowsheeting softwares like FLOWTRAN, ASPEN PLUS, PROCESS Mathematical modeling and simulation using FORTRAN, MATLAB, PASCAL Process design and application for Chemical Engineers through CAD/CAM (Computer Aided Design/Computer Aided Manufacturing)

3. Write in short about the role of chemical engineering in food industry. Production of Fertilizers, Pesticides and herbicides for growing food, production of flavour and additives, development of natural sweeteners, development of artificial sweeteners and food packaging

4. Write in short about the role of chemical engineering in medical field. Improvement in dialysis, improvement in treating diabetes, development of antibiotics and tablets and drug delivery

5. Write in short about the role of chemical engineering in energy engineering. • Traditional refining for coal, petrol, diesel, kerosene etc. • Electricity generation from coal • Biofuels like biodiesel, biomethanol, ethanol etc. • Use of Hydrogen as fuel • use of alternative energy resources like Solar and wind energy • energy development from Nuclear energy

6. Write in short about the role of chemical engineering in global environment. • Improvement in Transportation devices to save the environment • Reduction of industrial air pollution • Clean water production • To maintain the rule of 3R (Reduce, reuse and recycle) • Reduction of greenhouse gases to change the global environment 8

7. Write in short about the role of chemical engineering in biochemical engineering. • Upstream Production -fermentation reactor (fermentor) development and scale up -process control, optimization and troubleshooting of pilot plant and commercial scale fermentation processes. -in use of process control softwares, data analysis, design of experiments, and process modeling application packages. • Downstream processing -Removal of insoluble from product stream -Product isolation from a mixture of different products. -Purification of desired product to enhance quality -Product polishing to increase stability of final product

8. Write in short about the role of chemical engineering in electronic industry/ semiconductor processing. a) Development of semiconductor by chemical vapour deposition (CVD), electrochemical deposition and spin-on coating b) Removal of excess materials by dry etching or wet etching technique c) Development and maintenance of clean rooms for processing of semiconductor chips. These rooms have strict specifications such as one particle in a cubic foot.

9. Write the usage of chemical engineering software. (April-May 2018) Process design and application for Chemical Engineers through CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) Chemical engineering flowsheeting softwares like FLOWTRAN, ASPEN PLUS, PROCESS etc. are available by which steady state mass, energy balance, sizing and cost evaluation for a chemical process could be done Mathematical modeling and simulation using FORTRAN, MATLAB, PASCAL

10. Write the names of two flowsheeting softwares. FLOWTRAN, ASPEN PLUS, PROCESS etc.

11. What is mathematical modeling and what is simulation?. A chemical process/unit operation can be represented with mathematical equations which is called mathematical modeling. The model equations could be solved in computers which shows the predictive profile/output of future. This is called simulation. Computers are highly used by chemical engineers for modeling and simulation purposes.

12. What is the relationship between chemical and mechanical engineering?(April-May 2018) The most common subject is fluid mechanics. Chemical engineers study Heat and mass transfer in depth but that much depth is not provided to Mechanical Engineers.

Mechanical Engineers and Chemical Engineers both can deal with equipment design, manufacturing etc. but Chemical Engineers emphasize on process engineering. But in all cases equipment is a common thing because chemical industries deal with a lot of equipment.

13. What is the difference in simulation and optimization? The model equations could be solved in computers which shows the predictive profile/output of future. This is called simulation. To find the best combination of operating parameters to produce the maximum output when a large number of operating variables are involved is called optimization.

14. Write the names of two process simulation softwares. Mathematical modeling and simulation using FORTRAN, MATLAB

15. What is the relation in simulation and optimization? A chemical process/unit operation can be represented with mathematical equations which is called mathematical modeling. The model equations could be solved in computers which shows the predictive profile/output of future. This is called simulation. Computers are highly used by chemical engineers for modeling and simulation purposes. To find the best solution when a large number of operating variables are involved is called optimization.

16. What is the relationship between chemical and electrical engineering? a) Chemical Engineers used to manufacture the circuit materials as per the required specifications of Electrical Engineers. b) The electrical wire, insulated coating, heat insulation cover, electrically inert materials are industrially manufactured by Chemical Engineers. c) The most important operating device i.e. switch, made of Bakelite/plastic is supplied by different small/large scale Chemical companies.

d) Chemical Engineers also need to know the specifications and operating principles for pumps, motors and generators which are also part of Electrical Engineering.

17. What is the relationship between Chemical & Civil Engineering?

a) for a Chemical Engineering project, the estimation of land area, housing space requirement for project implementation could be prescribed by Civil Engineers. b) Civil Engineers work with building materials to construct strong structures. The control or/and improvement of quality of materials (eg.: cement, bricks etc.) are maintained by Chemical Engineers. c) The biggest common similarity of Chemical and Civil Engineering is towards environmental engineering, a multidisciplinary subject. Both of the engineering streams merge here to keep our environment clean through the pathway of sustainable industrialization.

18. Illustrate the differences in Traditional and Modern Chemical Engineering

 The traditional/classical/old Chemical Engineering used to be high energy, area and cost consuming. It used to be a tendency to use high temperature and high pressure to carry out a process.  But, now-a-days, the ‘Modern’ Chemical Engineering is moving towards the development of clean and green processes which will consume less cost, energy, area etc. Moreover, for any process of manufacturing and production, clean technology and cleaning technology are given importance.  Clean technologies are those processes which does not produce or produce minimum wastes. These processes are already clean enough to have ‘Zero Waste discharge’. To clean up the waste generated from existing processes, some waste minimizing techniques or treatment processes are employed which is cleaning technology.  Modern Chemical Engineering is much more inclined in favor of sustainability

19. What is meant by the Versatility of Chemical Engineering

Keeping aside the core regions chemical engineers play important and versatile roles in different industries like Food, Medical, Energy, Environmental, Biochemical and even in Electronics industries. These examples are chosen to show how the interdisciplinary nature of chemical engineering allows a graduate to fit into almost any industry. Such versatility helps the chemical engineer find employment in a wide spectrum of industries: from petroleum refining to semiconductor processing.

UNIT- V; Part A

1. What is meant by paradigm? Paradigm means a typical example or pattern of something; a pattern or model. The starting point is the paradigm definition as “a set of assumptions, concepts, values, and practices that constitutes a way of viewing reality for the community that shares them, especially in an intellectual discipline”.

2. What are the different paradigms of Chemical Engineering? The chemical engineering development is guided by its four main paradigms: unit operations, transport phenomena, product engineering and sustainable chemical engineering.

3. What is meant by paradigm shifts in Chemical Engineering? Due to the strict environmental regulations all over the world, the chemical, pharmaceutical and allied process industries are witnessing paradigm shift in their production strategy from the use of high temperature and high pressure processes to environment-friendly green technologies. New generation or next-gen production strategies that encourage clean production in more efficient, more energy-saving, compact, flexible yet small plant configuration in other words is termed process intensification (PI). Chemical and allied process industries are shifting towards clean technology and cleaning technologies to confirm sustainability through such process intensification.

4. What is meant by the Scale of production? The term, “Scale of production” refers to the size of the production unit of a firm or business. Depending on the size of production, it can be classified into large scale and small scale production. Generally, three scales are considered based on the range of product output: Bench scale (lab scale), Pilot scale and Industrial scale (commercial scale).

5. What are the different scales of Chemical Engineering? Generally, three scales are considered based on the range of product output: Bench scale (lab scale), Pilot scale and Industrial scale (commercial scale).

6. Define: Bench scale/ Lab scale of production. A designed process or a product is first produced in very small scale in laboratory. From here, the researcher gets an idea that the adopted process is suitable for production of desired product or not. If the experimentation live successful and all the desirability are met, then cost evaluation for the same process should be conducted and the same operation should be conducted in pilot scale.

7. Define: Pilot scale of production. A pilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology.

8. Define: Industrial scale of production. It refers to the production of a commodity on a large scale with a large sized firm. It requires huge investments in plant and machinery. Large scale production can be carried out if the market size is large and expanding.

Large scale firms are characterized by mechanization, division of labor and production and sale of goods in large quantities. They cater to a large market. The industrial revolution laid the foundation of the factory system. The factory system which extensively used machinery and adopted division of labor made large scale production possible.

9. What is scale up/ what is scale up factor? The capacity of production in lab scale is the lowest, pilot scale is low and industrial scale is the highest. But to predict the cost of a technology to bring from lab to industrial scale, scale up is required in economic evaluation. Cost of same equipment of higher capacity could be calculated using the standard equation: n capacity of high capacity equipment Cost of higher capacity equipment = Cost of lab scale equipment ×  capacity of lab scale equipment where, n represents the scale-up factor and differs for different equipment.

10. Write few job opportunities in chemical engineering field.  process engineering and control  production supervision  economical process analysis  product quality control  process validation  pollution control  health and safety aspects of manufacturing practises  computer-assisted design

11. Write few field specific job opportunities in chemical engineering.

a) Bioprocess : Biological production of food, drinks and pharmaceuticals Engineering eg: production of Insulin from E.Coli. b) Chemical : Chemical processing Technology for production of processing fertilizer, pesticide, herbicides, caustic soda, glass, specially chemicals. c) Combustion : Recovery of energy from coal/natural/renewable resources to energy. d) Environmental : Water & waste water treatment, environmental regulation, recovery & reuse of valuable material. e) Mineral : Processing of ores like copper, lead, gold. f) Petroleum & : Conversion of natural gas and oil to fuel, synthetic rubber petrochemicals and LPG, plastics.

9 g) Project Delivery : Conversion of a process plant to a safe an efficient one to run the process run smoothly and safely. h) Research & : Development of new product/process integration in lab,. Development Evaluation of production cost and commercial implementation after patenting. Organizing workshops/conference for spreading knowledge in other people.

12. What are the objectives to be met in the future of chemical engineering? The future of chemical engineering can be summarized by four main objectives: (1) Increase productivity and selectivity through intensification of intelligent operations and a multiscale approach to process control; (2) Novel design equipment based on scientific principles and new production methods: process intensification; (3) Extended chemical engineering methodology to product design and product focussed processing using the 3P Engineering “molecular Processes-Product-Process” approach; (4) Implemented multiscale application of computational chemical engineering modelling and simulation to real-life situations from the molecular scale to the production scale.

13. What do you think about the broader future of chemical engineering? a) Space Fuel Processing for Space shuttle to make it less costly and long lasting. b) Nuclear Recycling like uranium recyclers, will be needed for use in nuclear power plants to ensure that the uranium shortage does not cause an energy crisis. c) Genetic Farming could be the option for future to raise livestock and agricultural crops to solve food problems. d) Nano-manufacturing of catalyst, chemicals, nanorobots for production, reaction and medical purposes. e) Smart city project development f) Simplicity in production process and plant design for both upstream and downstream processes paves the pathway towards future. g) Green Process Engineer through the achievements in sustainable technology, water management and energy efficiency, chemical engineers being the Green process engineers will develop environmentally benign chemical processes and products.

14. Define the term day shift and mention its time. (April-May 2018) Chemical Industries Now-a-days run in continuous way, mostly without any break in operation. The engineers work in those production industries has to maintain 3 timings during their job. The Day shift starts in the afternoon session (2 P.M.) and continues to night (10 P.M.). Day shift timing: 2 P.M. to 10 P.M.

15. Illustrate the three types of shifts used in chemical industries. (April-May 2018) Chemical Industries Now-a-days run in continuous way, mostly without any break in operation. The engineers work in those production industries has to maintain 3 timings during their job. These are: Morning shift, Day shift and Night shift. Morning shift: 6 A.M. to 2 P.M. 10

Day shift: 2 P.M. to 10 P.M. Night shift: 10 P.M. to 6 A.M.

16. Write the shift timings in chemical industries. Morning shift: 6 A.M. to 2 P.M. Day shift: 2 P.M. to 10 P.M. Night shift: 10 P.M. to 6 A.M.

V.S.B.ENGINEERING COLLEGE, KARUR DEPARTMENT OF CHEMICAL ENGINEERING

CH8201 PRINCIPLES OF CHEMICAL ENGINEERING QUESTION AND QUESTION BANK PART B

NAME : BRANCH : ROLL NO. :

Prepared by Department of Chemical Engineering V. S.B. Engineering College, Karur

Unit I: Part-B 1. Define chemistry, chemical engineering and chemical technology.

Chemistry:

The branch of science concerned with the substances of which matter is composed, the investigation of their properties & reaction & the use of such reactions to form new substances is chemistry. Chemical Engineering: It is the study and practice of transforming substances at a large scale/quantity for the commercial production for the real use and improvement of human beings. Such industrial application we can see in transformation of natural or waste substances to useful substances or energy in the field of chemical, petroleum, pharmaceutical, electronics & energy production industries. Typically the ‘scale’ of production depends on all sizes ranging from barrels to tank cars or lab to industry.

Lab Scale (bench scale) Pilot scale Industrial production

Chemical Technology: It is the study of organic or inorganic chemistry, industrial & physical chemistry, quantitative & instrumental analysis & chemistry related to oil, gas, agricultural, food & environmental sectors, chemical technologists provide technical support to the people in chemical related fields, to set up labs & to conduct chemical experiments under the guidance & supervision of Chemical Engineer.

2. Differentiate chemistry, chemical engineering and chemical technology. a) The main difference in Chemical Engineering and Chemistry is the scale of application. People of chemistry generally carryout experiments in labs and report on the development of a new chemical. But, to bring the small lab scale production to industrial scale, Chemical Engineers are required. b) Chemistry is mostly focused on reaction & testing of chemicals but Chemical Engineering is focused on production, product development, in-depth design of process technology & reactor design. Side- by-side a chemical engineer needs to have a good knowledge on process economics so that the cost of developed product could be lessened. c) Education is also one key issue. Chemistry deals with reaction, reaction kinetics with basic or advanced theoretical approaches. Chemical Engineers study the advanced courses of application oriented courses of Physical Chemistry, Biochemistry, Polymer or Organic Chemistry with subjects of deep knowledge of heat transfer, mass transfer, fluid mechanics, bioprocessing and reactor design. Chemical technologists study General Chemistry, Physics, Instrumentation & Analytical analysis of Chemistry.

d) Chemical technologists work is to maintain laboratory or industrial applications and to assist a Chemical Engineer for successful production of chemicals and running of a chemical plant. e) Chemistry Product development by reaching in lab, testing of product. Chemical Engineering Process development, reactor design for production in industrial scale. Chemical Technology Assist, monitor, maintain Lab/industry under the supervision of Chemical Engineer.

Example: Let’s assume, a Chemical Engineer has developed a new eco-friendly product/ medicine in the Lab. After development he will send the product to Chemistry (Chemistry) for qualitative (how good is the product) & quantitative (how much quantity/concentration) analysis.

3. Explain in detail about the history and role of chemical engineering in society. (April-May 2018)

History of chemical engineering  In the history of development of different engineering practices, Chemical Engineering is a relatively younger, about 100 years old profession.  The industrial revolution started at the time of mid of 1800 to 1900 led to high demand and production of chemicals.  Generally mechanical engineers who had knowledge in Industrial Chemistry used to handle such plants.  But it was inconvenient for those people due to lack of fundamental knowledge. In similar production plants they used to find themselves unsuitable.  Chemical Engineering was first established as a profession to bridge up the gap of knowledge of chemical processing reaction and process monitoring Technology.  The first Chemical Engineering course was given at the University of Manchester in 1887 by George E. Davis, who is said as the father of Chemical Engineering and the first Chemical Engineer.  The 12 lecture series of Davis formed the Handbook of Chemical Engineering. The fundamental similarities observed in different processes in various plants led to the concept of unit operations involving physical phenomena in chemical process technologies.  USA felt interest on the lectures and chemical curriculum started in 1888 in MIT.  In 1908 American Institute of Chemical Engineers (AICHE) was formed.  Demand of ‘Horseless Carriage’ got accepted and demand of gasoline started to shoot up.

 In 1960’s the computer Aided Design (CAD) package was developed which allowed process design with simplicity.  Beginning in the mid of 1990’s new areas of development like Microelectronics, Pharma, biotech, nanotechnology started to merge with Chemical Engineering.  Industrial revolution started to begin with a shift from batch to continuous mode of production.  Today about 70,000 types of commodity chemicals are produced by Chemical Engineers.

The role of a Chemical Engineer

 Chemical Engineers translate process developed in lab to the practical Industrial applications for the commercial production of desired products & to maintain & improve the process of production.  Relying on the main foundations (mathematics, physics, chemistry & biology) the chemical engineers play a key role in designing & troubleshooting processes for the production of chemicals, foods, pharmaceuticals, fuel & energy.  The chemical engineers are given the charge to manufacture a product with high productivity while reducing the cost of production without compromising the quality of desired product.  Chemical Engineers ensure compliances with health, safety & environmental regulations.  They conduct research to improve manufacturing process and product quality.  They are able to design and plan equipment & operating system layout.  Maintenance of process safety during operation.  Monitor & optimize the production performance while minimizing the production cost in a cleaner and safer plant.  The Chemical Engineers can work in diversified fields like:-

a) Bioprocess : Biological production of food, drinks and pharmaceuticals Engineering eg: production of Insulin from E.Coli.

b) Chemical : Chemical processing Technology for production of processing fertilizer, pesticide, herbicides, caustic soda, glass, specially chemicals.

c) Combustion : Recovery of energy from coal/natural/renewable resources to energy.

d) Environmental : Water & waste water treatment, environmental regulation, recovery & reuse of valuable material.

e) Mineral : Processing of ores like copper, lead, gold.

f) Petroleum & : Conversion of natural gas and oil to fuel, synthetic rubber petrochemicals and LPG, plastics.

g) Project Delivery : Conversion of a process plant to a safe an efficient one to run the process run smoothly and safely.

h) Research & : Development of new product/process integration in lab,. Development Evaluation of production cost and commercial implementation after patenting. Organizing workshops/conference for spreading knowledge in other people.

4. Write about the eminent personalities of chemical engineering. a) George Edward Davis: Known as the ‘Father of Chemical Engineering’, who gave the first 12 lectures on the need of a separate Engineering approach to explain what Chemical Engineering actually is. He wrote a book on ‘A Handbook of Chemical Engineering Vol. I & II’ which explains the how industrial operations to be done in industrial scale. b) Arthur D. Little: It is a famous international consultancy firm but the man who framed it was a chemical engineer who laid the foundation of unit operation. c) John. H Perry: He edited the ‘perry’s handbook for Chemical Engineers’ published in 1934. He was a Ph.D. holder and a Chemical Engineer. His handbook contains all important properties and system handling knowledge to teach and practice Chemical Engineering. d) Robert Samuel Langer Jr.: Known as ‘Father of Tissue Engineering’. He has significant contribution in medicine & biotechnology & invented new technology like drug delivery systems. e) Thomas H. Chilton: Known as ‘Father of modern Chemical Engineering Practice’ and developed Chilton-Coulburn analogy which is widely used in heat and mass transfer. He worked as a Chemical Engineer at Dupout for 35 years and gave understanding reports on heat and momentum transfer. f) Elmer L. Gaden Jr.: Known as ‘Father of Biochemical Engineering’ who worked on penicillin production. g) Carl Bosch & Fritz Haber: Haber invented Haber process for production of Ammonia where nitrogen and hydrogen at high temperature & pr react to form Ammonia. Carl Bosch scaled up the process from lab scale to Industrial production. This process enabled the production of synthetic fertilizers that contribute to the half of world’s food production. h) Margaret Hutchinson Roussan: Margaret was the first female to receive Doctorate degree from MIT in Chemical Engineering. She is mainly known for producing the first commercial penicillin production plant and contributed to creating processes which produced high-octane gasoline.

i) Vladimir Haensel: Holding nearly 150 patents and 400 foreign patents, Vladimir is famous for platforming process where platinum is used as a catalyst for production of clean, low-cost gasoline, containing high energy.

5. Write about the greatest achievements by chemical engineers to this world./ Discuss in detail about the greatest achievements of chemical engineering. (April-May 2018) a) Generation of fossil Fuel: By the cracking of hydrocarbon molecules resulted high octane gasoline to jet fuel, from chemical derived from natural gas to the thermal/ catalytic cracking of fossil fuel to petrol or diesel — the World economy depends on the Chemical Engineers. b) Energy Production (Electricity): Chemical Engineering always provided newer options with novel technologies for power generation. From coal based power plant to newer generation of nuclear power plants, everywhere chemical engineering is applicable. c) Downstream Purification: Reverse osmosis for water treatment, Bioreactors for waste water treatment, production of safer fertilizer, Development of pure product by distillation, chemisoption produced more pure substances. d) Catalytic Converter: Use of Catalytic converter cleaned up the produced NOx and other hydrocarbons coming from automobiles. e) Polymer & plastic: Continuous inventions and commercialization improved the journey of human society to a modern one. Use of polymeric fibre like Nylon, Rayon, Polystyrene in clothing, Polyethylene terephthalate (PET) in bottles, Bakelite, a thermosetting plastic are used in our day to day life. f) Polymer & Rubber: Use of Rubber as stretchable material is applied in tire improvement, military, household and industrial sectors. g) Product Manufacturing: Introduction of stainless steel in reactor development, chrome plating for protection of iron & steel products provided more longevity in manufacturing processes. h) Fertilizer & Pesticides: Development of Chemical Fertilizer and pesticides solved the food production of the world, use of aluminum foil for food supply made life more convenient. i) Medical Research: Development of new medicines, vaccines, dialysis process, production of penicillin, painless micro needles save many life of human beings. j) Computers & Chemical Engineering: Development of optical fibre for fast data transfer, softwares like ASPEN, HYSIN enhanced process simulation, design and Development. By the mass production of silicon microchips computerized automation turned successful.

6. Elaborate the Role of Chemical process Industries in Society. By converting the raw material to products, about 70,000 different types of products are obtained from different sectors of chemical process industries. It includes production of basic chemicals and products,

6 petrochemicals, fertilizers, paints, greases, soap & detergent, perfumes, medicines and speciality or fine chemicals, which is used in daily life from Industries to household. It takes an important role in the development of a country’s economy & in India it contributes about 6% of the overall Gross Domestic potential. Major products and their Application in Society

Sl. Common name Molecular formula Use No.

1. Baking Powder NaHCO3 Cooking

2. Soap/Detergent Ester/Alkylbenzene sulphate Cleaning

3. Toothpaste CaCO3, Na2F Teeth & gum care

4. Salt NaCl Cooking

5. Vinegar CH3COOH Food preservation, additive, Taste

6. Bleaching Powder NaOCL Cleaning, pest removal

7. Aspirin C9H8O4 Medicine

8. Caustic Soda NaOH Cleaning, Catalysis

9. Fertilizer (synthetic) Ca(HPO4)2, Nitrogen & Food production phosphate salts

10. Pesticide or Organochloring, Food production Agrochemicals organophosphates, carbamates, DDT

11. Synthetic fibre, Cellulose Actate Clothing textiles

12. Dye Coloring of cloth

13. Polymer coat, paint Sheltering, lifestyle, wall coloring

More than all these things, chemical industries by the production of variety of chemicals take part in health care by production of different detergent, polymers and medicines. The quality of social life by providing fuel, education, Electricity, Energy, water supply, communication, is being steadily updated and upgraded by the role of chemical industries.

7. Describe the history of Chemical Process Industries

 One of the primary chemicals that was industrially produced was Sulphuric Acid (H2SO4). In 1736

in England, Joshua Ward started a small scale H2SO4 production plant by burning a mixture of sulphur and potassium nitrate to oxidize sulphur and combining with water.  The scale of production was increased by John Roebuck in 1747 using large chambers of lead on wooden frames. By the introduction of circulatory system & counter – current absorption, the process became a continuous system employing a homogeneous catalyst Nitrogen-di-oxide. This process became a paramount importance in British Chemical Industry.  Chemicals for Textiles: Discovery of bleaching powder by Charles Tennant by rreaction of Chlorine

with dry slaked lime (Ca(OH)2). His factory started in 1799 with 52 tons of production which became about 10,000 tons within 5 years.

Production of Soda ash (Na2CO3) was industrialized by Nicholas Leblanc. Using the patented process

where NaCl is reacted with H2SO4 to produce Na2SO4 and further reaction with CaCO3 to produce

Na2CO3, the production reached about 20,000 tons in Britain.

2NaCl + H2SO4 Na2SO4 + 2 HCl

Na2SO4 + CaCO3 + 2C Na2CO3 + CaS + CO2.  Coal carbonization: Coke from coal was produced for metallurgical use early in 18th Century. In early 19th Centuries the lightning potential of coal gas was appreciated.  Development of explosives from Coal Tar like TNT (Trinitro toluene), Picric acid, nitroglycerine was started to be produced from 1850.  Ammonia-Soda Process: Though the process started from 1811 but the success in industrial scale came in 1865 in Belgium by Solvey who overcame the problems of gas handling.

CaCO3 CaO + CO2.

CaO + 2NH4Cl CaCl2 + 2NH3 + H2O.

2NH3 + 2H2O + 2CO2 2(NH4) HCO3.

2(NH4)HCO3 + 2NaCl 2NaHCO3 + 2NH4Cl

2NaHCO3 Na2CO3 + H2O + CO2. Net reaction:

CaCO3 + 2NaCl Na2CO3 + CaCl2.  Nitrogen Fixation/Haber Process:

Production of Ammonia (NH3) was first commercialized by German Scientist Haber and Bosch in o 1913. At 150-200 atm & 400-500 C, N2 & H2 react to form Ammonia in presence of Catalyst Al2O3.  Synthetic dyestuff manufacturing started from 1857 in Germany. Major industries like BASF, Bayer, Hoechst produced 80% of the World dyes.

 Production of Artificial fertilizer started in London by the commercial production of Ca(H2PO4)2 or super phosphate of lime in the 1840’s.

 Chemical firms from 19th Century started to have expansion with maturity. Production of Rubber, plastic & the growth of petrochemical industries to polymer production companies are taking a huge role in the growth of chemical productions which are being used in daily lives.

8. Classify the major Chemical Process Industries with examples

Chemical process industries are those where the raw materials undergo chemical conversion or physical conversions during their processing to finished products. a) Chemical industries are broadly classified in two groups based on quantity of production & consumption: i) Heavy Chemicals: Produces simple compounds from locally available large amount of raw materials. Usually they are very large industries and the products purified to such an extent that they could be used as raw material for other industries (directly marketable). Large quantity production in large industries to produce crude/less pure product.

eg: NaOH, Na2CO3, Mineral Acid. ii) Fine Chemicals: Products are speciality chemical & are produced in small quantity with very high purity as finished goods. eg: Special solvents, medicines, organic acids (Acetone, Acetonitrile). b) Based on chemical composition:

i) Organic Chemicals: products are having organic carbon atoms in molecules. Eg: hydrocarbons, phenol, organic acids

ii) Inorganic Chemicals: products are having no organic carbon atoms in molecules. Eg: NaOH,

K2Cr2O7

iii) Polymers: products are having big macromolecular structure formed by covalent bondings. Eg: polystyrene (rubber), Poly vinyl chloride c) Based on availability:

i) Natural: products are processed after being naturally extracted. eg: coal, petrol, natural gas

ii) Synthetic Chemicals: products are entirely man-made and not naturally extracted. Eg: NaOH,

K2Cr2O7 , Poly vinyl chloride d) Based on application:

i) Catalyst: products are used as catalyst in different process industries. Eg: AlCl3, MnO2, platinum

ii) Drug/Medicines: products are used for medicinal purposes. Eg: Paracetamol, pantafol

iii) Resin: products are used as cation or anion exchange purposes. Eg: urea formaldehyde, epoxy resin, polyester

9 iv) Dye: products are used as coloring agent or pigments. Eg: Methyle red v) Solvent: products are used as solvents of chemical reactions. Eg: benzene, ethanol, di methyle formamide (DMF) vi) Food production: fertilizer, pesticides vii) Miscellaneous: glass, cement etc.

Unit-2

1. Write in brief about role of physics in chemical engineering.

 The major part of chemical engineering is organizing the physics of a system (physical or chemical process) to work and to get desired output. For example, the mechanics of a pressurized vessel should be understood so that the pressure vessel does not burst or a distillation column do not fail. Handling with energy (heating/cooling etc.) should be understood very well along with the flow of heat in a physical system. A simple compound which is prepared by simple stirring in lab, cannot be manufactured in a huge quantity in an industry without facing complexities of the physical/real world. Interaction of two entities during a reaction is also governed by the laws of physics.  Physics is the eye to see the true existence of nature and physical phenomenon to explain all micro and macro level scenario. Chemical Engineers need to deal with very fine charged particles and ionized gases. When there is flow of charged particles, or electron flow, there is flow of current or electricity. By the generation of electric field, there would be generation of magnetic field.  Chemical Engineers need to deal with thermodynamics which is dealing with relationships between heat and all other forms of energy (mechanical, electrical or chemical energy) which is driven by the fundamental principles of physics. For any physical system, the three laws of conservation of mass, momentum and energy should be obeyed to analyze the specific physical or chemical reacting systems. Types of Systems:

A) Control mass system or closed system: a) System of fixed mass or identity b) No mass transfer across Boundary c) Energy transfer may happen in or out of the system. eg: A nuclear reactor.

B) Control Volume System or open system: a) System of fixed volume.

b) No transfer/change in volume but transfer of mass and energy may occur across control boundary. c) Most of the engineering devices use this concept. eg: Heat exchanger & pumps.

C) Isolated System: a) System with fixed mass or fixed identity. b) No interaction of mass or energy across the system boundary with the surroundings. eg: Thermoflask.

Laws of Conservation:

1. Conservation of mass: Mass can neither be created, nor be destroyed by any chemical reaction or physical process.

eg: CH4 + 2O2 CO2 + 2H2O. Where one molecule of methane is reacting with two molecules of oxygen, to form carbondioxide and water. The number of molecules of carbon, hydrogen and oxygen are same even after the reaction. 2. Conservation of momentum: The net momentum of a system is constant if no external forces acting on the system. This fact, known as the law of conservation of momentum, is implied by Newton's third laws of motion 3. Conservation of Energy: The total energy of an isolated system is constant. It can neither be created nor be destroyed.

2. Describe the role of mathematics in chemical engineering

 A wide number of variables are required to be taken care off during a practical problem like distillation, absorption or in case of reaction engineering, the mathematics play the crucial role in solving complex equations.  To solve the process control systems of first / second / higher orders, laplace transformation helps to quickly and smoothly reach towards solution.  To conduct one experiment successfully, huge investment cost is involved. If something is wrong in the production, whole batch will be wasted. So, the involved money, man power will be spoiled. So there is a need of mathematical techniques for modeling and simulation of a practical system to predict the system performance and product quality.  The laws chemical engineers follow for theoretical analysis are all mathematical expressions, like Vector algebra, ODE, PDES, integration, laplace transformation etc. So mathematics play an important role in the concept of chemical engineering. eg:

dC a) Mass transfer: Ficks Law of diffusion: J = - D A A dx J is the diffusion flux, (mol m−2 s−1) or is amount of substance diffused per unit area per unit 2 3 time. D is the diffusion coefficient or diffusivity ( m /s.). CA is the concentration (mol/m .) and x is position (m).

dT b) Heat transfer: Fourier’s Law of Heat conduction: QKA dx Q is the total heat transferred (W), K is the material's conductivity (W·m−1·K−1), T is the temperature gradient (Kelvin), A is area of heat transfer area (m−2) and x denotes position (m). dq Newton’s Law of Cooling:  hA  T dt q is the thermal energy (Joule) and t denotes time (sec). h is the heat transfer coefficient, (W/(m2 K)) A is the heat transfer surface area (m2), T is the temperature (kelvin). F du c) Momentum transfer / fluid mechanics: = τ = - μ (Newton’s Law of Viscosity) A dy u is velocity (m/s), y denotes position (m), µ is dynamic viscosity (cm2/s), and τ is the amount of shear stress (Pascal-second). d) Process Control: If, the transfer function of a 1st order system is G t  eat at t  0 Then, G S  L eat 

1  Sa

3. Write in detail about he role of chemistry in chemical engineering (April-May 2018).

 Though Chemical Engineering is mostly based on the concepts of Physics, Mathematics but as it is involving the commercialized production of chemicals at an industrial scale, basic knowledge of chemistry is a must. The concept of redox reactions, electrons or charged particle transfer, reaction kinetics, reaction parameters, equipments for chemical production is very much necessary to learn and apply the knowledge of Chemical Engineering.  Industrial Chemistry plays a major role in providing proper direction to the chemical engineers. The existing plants, production processes of commercial chemicals, equipment design, the raw materials required to get desired product, use and development of catalyst, intensification of reaction by the use of catalyst, are the knowledge which is provided by the subjects like basic and industrial chemistry.  The concepts of reactor design for a specific chemical reaction, the type of reaction (endothermic or exothermic) by the use of a specific catalyst, the reaction thermodynamics are derived from the concepts of chemistry which are highly applicable in chemical engineering.  The concept of molecular weight, equivalent weight, concentration, molecular and atomic mass, the proper balancing of reactions for industrial applications are derived from the concept of chemical Stoichiometry.  For preparation of stock solution or a dilute solution, for any acid/base solution or to conduct, any acid/base reaction, concept of chemistry is very necessary to be applied in Chemical Engineering fields, because of the use of units like molarity (M), normality is widely done.

4. Discuss in detail about the role of Biology in Chemical Engineering (April-May 2018)  Chemical Engineers and biologists collaborate to generate cross disciplinary subjects like Biotechnology, industrial biotechnology, biochemical or bioprocess technology. As Chemical Engineering is basically the industrial production of commodity chemicals, a lot of process technologies are present which involve biological species like microbes and other living species.  To handle the microbes and to produce/extract organic acids/proteins from the cells proper knowledge of industrial biotechnology is required to control the upstream or production

process. Chemical engineering could get involved in the downstream purification of the product to maintain and increase the product purity or quality.  Different types of proteins, vaccines, immunity growing drugs and medicines are developed from the integration of chemical engineering and bioprocess and pharmaceutical engineering technologies.  Development of Biomedical engineering as a separate educational stream is fostering the growth of industrial production of life saving drugs. But the industrial productions of Biotechnology / Biochemical / pharmaceutical / bioprocess engineering are based on Chemical Engineering principles.

5. Describe Newton’s law of viscosity. Newton’s law of viscosity states that the shear stress between adjacent fluid layers is proportional to the velocity gradients between the two layers. The ratio of the shear stress to shear rate is a constant for a given temperature and pressure and is defined as the coefficient of viscosity.

du  dy

du  dy Where,

T is Shear stress = F/A μ Viscosity du/dy is the rate of shear deformation

6. Explain the three modes of heat transfer. Heat transfer which is defined as the transmission of energy from one region to another as a result of temperature gradient takes place by the following three modes:

15 a) Conduction- The transfer of heat only due to relative molecular vibration of substance is heat conduction. It is the transfer of heat from one part of a substance to another part of the same substance, or from one substance to another in physical contact with it, without appreciable movement of molecules forming the substance.

dT Fourier’s Law of Heat conduction: QKA dx

Q is the total heat transferred (W), K is the material's conductivity (W·m−1·K−1), T is the temperature gradient (Kelvin), A is area of heat transfer area (m−2) and x denotes position (m).

b) Convection- It is the transfer of heat within a fluid by mixing of one portion of the fluid with another. dq Newton’s Law of Cooling:  hA  T dt q is the thermal energy (Joule) and t denotes time (sec). h is the heat transfer coefficient, (W/(m2 K)) A is the heat transfer surface area (m2), T is the temperature (kelvin).

c) Radiation- It is the transfer of heat through space or matter by means other than conduction or convection. Stefan- Boltzmann law states that the total radiant heat energy emitted from a surface is proportional to the fourth power of it’s absolute temperature. It applies to blackbodies and theoretical surfaces that absorb all incident heat radiation. E= σT4 Where, E is the radiant heat energy emitted from a unit area in one second

T is the absolute temperature σ is the Stefan-Boltzmann constant

7. Explain Conservation of momentum.

Conservation of momentum: The net momentum of a system is constant if no external forces acting on the system. This fact, known as the law of conservation of momentum, is implied by Newton's third laws of motion

If two bodies of mass m1 and m2 are interacting with each other with velocities of v1 and

v2, the force applied by m1 on m2 is F12 and the force applied by m2 on m1 is F21. Now as per Newton’s law of motion:

F12 = -F 21

or, m1 a 1 +m 2 a 2 =0 dv dv or, m12 +m =0 12dt dt dm v dm v or, 1 1 + 2 2 =0 dt dt d(m v +m v ) or, 1 1 2 2 =0 dt

 m1 v 1 + m 2 v 2 =constant

8. Derive continuity equation in (1-D) one dimensional flow.

Let us consider a tube of flow as shown in the Figure. The areas of cross section perpendicular to fluid flow at positions P and Q is A1 and A2 respectively. v1 and v2 are the velocities of fluid entering at P and leaving at Q.

The mass of fluid crossing the surface A1 in the time interval is,

Fig.8 : One Dimensional flow and the mass of fluid leaving the surface A2 during the same time interval is, where and are the densities of liquid at positions P and Q.

No fluid can leave through the walls and there is no source or sink in the above tube, i.e., in the control volume.

So, as per conservation of mass,

or,

9. What are the roles of Thermodynamics in Chemical Engineering?  Thermodynamics provides an idea about various energy interactions, mostly heat and energy transfer. It describes about transformation of heat (form of energy) to some other form, the maximum usefulness or availability (energy) of a system and how equilibrium of energy is reached when the system is interacting between the surrounding.  Thermodynamic equilibrium as represented by Gibb’s phase rule (G=C–P+2) is widely used in Chemical Engineering to find the state of a material which limit the operation of a homogeneous/heterogeneous system.  In case of reactions, the displacement of equilibrium could well understood by Le Chatelier’s principle which is employed in reactor design and reaction input-output strategies in an industrial scale of chemical production.  Activation energy of a reaction could be found by Arrhenius equation:-

E . KAexp RT 

 Concept of Chemical Engineering is highly dependent on the concept of thermodynamics. The reaction dynamics/kinetics, heat of reaction, catalyst activity, progress of reaction, to reactor design are dependent on the concepts of thermodynamics.

 Chemical Engineers need to follow the laws of thermodynamics to tackle a practical situation of production. a) First Law of Thermodynamics: Also known as the conservation of energy which states energy can neither be created nor destroyed. It only changes from one form to the other. Change in internal energy = E = heat flow across the boundary + work done on the system = q + w b) Second law of thermodynamics: Entropy (randomness) of an isolated system never decreases but always increases, simply we can say the entropy of universe (ultimate isolated system) only increases and never decreases. dQ 0 T

Entropy 0 c) Third law of Thermodynamics: Entropy of system reaches a constant value as the temperature reaches absolute zero. The entropy of a system at absolute zero is typically zero. d) Zeroth Law of Thermodynamics: If two thermodynamic systems each are in thermal equilibrium with the third one, then they are in thermal equilibrium with each other.

A Thermal Thermal Equilibrium Equilibrium

B C Thermal Equilibrium

10. Describe the Role of Transport Phenomena in Chemical Engineering.  Transport phenomena is the unified description of heat, mass, momentum transfer, their analogy and dependence on each other during a practical problem. Transport phenomena brings deep mathematical connections and frameworks among all the transfer processes.  For a practical R & D or industrial process involve fluid flow inside a reactor to carry out reaction, which could be end a or exothermic in nature. For those situations, heat transfer, mass transfer, fluid mechanics and if required reactor design/reaction kinetic knowledge is necessary.  The basic transfer equations could be used for more difficult purposes to solve/model such cases containing multiple transport processes in a single system.

By following the basic transport equations, we can note an analogy among them:

For all cases, flux is directly V I  proportional to gradient These are also analogous to ohm’s law = R .

So, flux = constant × gradient. Potential Or, Rate of Flow = Resistance .

Fluid Mechanics / Heat Transfer Mass Transfer Momentum Transfer

dT QKA dx dCA du JDA AB τ = - μ Q dT dx dy Or qK   A dx

constant = Thermal conductivity constant = Diffusivity constant = viscosity (thermal diffusivity) (mass diffusivity) (momentum diffusivity)

dT dC du Potential= Potential = A Potential = dx dx dy

Resistance= - 1/KA Resistance= - 1/DAB Resistance= - 1/µ

11. Explain the role of Chemical Kinetics in chemical engineering.  As the Chemical Engineers mostly deal with production of chemicals at an industrial scale, role of chemical kinetic theorems are highly important and applicable for Chemical Engineers to carry out a reaction at an industrial scale, to design a reactor or to predict the system performance. Along with those factors, proper choice of reactors are also important to carry out desired reactions to generate desired product.  By the knowledge of Chemical Kinetics, a chemical engineer is able to understand how fast a reaction is occurring. This is the base line from where the chemical reaction engineering is developed where the concept of thermodynamics and physical chemistry is integrated to design a chemical reactor for industrial production of chemicals.  A chemist is successful to carry out a reaction in a small lab scale but he is more interested in finding the mechanism of the reaction and molecular structure of that developed product. But for a chemical engineer, these information are not of that much concern. Rather by the laws of thermodynamics he is more interested to build a reactor for the particular production. Gibb’s free energy change and heat of reaction (Thermodynamics) indicates a reaction is feasible or not. If it is negative, the reaction can take place. The concept of reaction rates

(physical chemistry) lets us understand that how fast a reaction can proceed to form the end product, or how the reaction could be controlled to minimize the by-product and maximize desired product.  The time spent by any react and inside a reactor is called residence time. In slow reactions, the residence time is very high.

In case of exothermic reactions, if the reactor is cooled or the heat of reaction could be removed, then the rate of product formation could be improved.

Reactions could be homogeneous (single phase of gas / liquid / solid anyone) or heterogeneous (more than one phase like, gas-liquid, liquid-solid or gas-solid mixture) based on which there are classical reactors –

a) Batch reactor b) Continuous stirred tank reactor (CSTR) c) Plug flow reactor (PFR)

These are also called as ideal reactors.

Batch CSTR PFR

Reactants are added and well Continuous operation, with i Continuous operation in a tubular mixed, product collection at the of reactants and outlet of reactor velocity is uniform across end of reaction. products. Homogeneous the cross section. Composition is reactor due to continuous Homogeneous:Uniform conc., assumed to be radically uniform. pH, temperature stirring.

For a single phase reaction in an ideal reactor aA bB  rR  sS , the rate of reaction for reactant A is:

1 dN moles of A disappearing -r = -A = A v dt Volume of reactor . Time

(-) minus sign signifies the disappearance or loss of A.

12. Discuss in detail about the role of Process Dynamics, Design and Control in chemical engineering with neat sketch (April-May 2018)

We need control systems for needs like:

a) To suppress the influence of external disturbances b) To ensure the stability of a running process c) To optimize the performance of a chemical process.

Moreover, now-a-days, the plants are getting updated from manual to semi-automatic to fully-automatic processes. There are the uses of Digital Control System (DCS) which is basically the brain of a control system.

The advantages of analysis of process dynamics, design and control systems are:-

Block diagram of a closed loop control system

Disturbance

+ Set Controller Final control element Process Output Point –

Measuring device

1. Set point or reference point is a specific set of input values of signal to produce a specific action.

2. Controllers receive the process variables and compare with the value of set point. Then they send a feedback or controller output to the final control element. 3. Final control element is a device that directly controls the valve of a manipulated variable in control loop eg: a control valve for controlling heat/energy/fluid flow. 4. Process could be any physical or chemical process which is being controlled to produce the optimum output. 5. Disturbances are the undesirable input signals that upsets the value of controlled output of a process. 6. A measuring device could be any device which measures the valve of controlled output and send the signal to the summing point to compare with the valve of set point.

13. Draw the generalized process control system and explain it.

Block diagram of a closed loop control system

Disturbance

+ Set Controller Final control element Process Output Point –

Measuring device

1. Set point or reference point is a specific set of input values of signal to produce a specific action. 2. Controllers receive the process variables and compare with the value of set point. Then they send a feedback or controller output to the final control element. 3. Final control element is a device that directly controls the valve of a manipulated variable in control loop eg: a control valve for controlling heat/energy/fluid flow. 4. Process could be any physical or chemical process which is being controlled to produce the optimum output. 5. Disturbances are the undesirable input signals that upsets the value of controlled output of a process. 6. A measuring device could be any device which measures the valve of controlled output and send the signal to the summing point to compare with the valve of set point.

14. What is the role of Laplace Transform in process control? Explain in the aspects of process dynamics and control with some important Laplace functions. The use of Laplace transforms offers a very simple and elegant method of solving linear or linearized differential equations which result from the mathematical modeling of chemical processes. The Laplace transforms also allow: a) Simple development of input-output models which are very useful for control purposes. b) Straightforward qualitative analysis of how chemical processes react to various external influences. Laplace transform is an integral transform that takes a function of a real variable t (often time) to a function of a complex variable s (complex frequency)

Considering a function f(t). The Laplace transform of the function is represented by f(s) and defined by the following expression:

If, the transfer function of a 1st order system is G t  eat at t  0

   Then, G S  L eat  G() t e  st dt  e  at e  st dt  e () s  a t dt   0   0    0 1  Sa

Hence, the Laplace Transform is a transformation of a function from the t -domain (time domain) to s -domain (Laplace domain) where both t and s are independent variables.

Few basic functions which are frequently used in process control applications are shown below:

(a) Step function (b) Ramp function

Unit-III , Part B

1. Draw the chemical engineering tree. Define unit operations and unit process. Describe in detail about unit operations and unit process with few examples.

Chemical engineering tree

Unit operations: The operations which involve only physical operations and not chemical operations are referred as unit operations. eg.- Fluid flow, heat transfer, distillation, crushing, grinding and crystallization etc.

Unit process: The processes where in a chemical reactor, reactions occur and reactants get converted to products are referred as unit processes. eg.- sulphonation, nitrification, esterification, alkylation etc.

Different unit operations:

Distillation: The unit operation where the separation is based on the boiling points of the constituents is called distillation. This is essentially a mass transfer operation where a mixture of two or more components boil. The vapor phase becomes richer in more volatile or ‘lighter’ components and liquid phase becomes richer in ‘heavier’ or less volatile components.

yyAB/  AB  xxAB/

Heat Exchanger: A heat exchanger is a device to transfer heat between two or more liquids. It could be used for both the purposes of heating and cooling, where the fluids are separated by a soil wall to avoid direct mixing. These are widely used in industries for space heating, refrigeration, air conditioning, power plants and chemical plants etc.

Such equipment employ both the principles of fluid mechanics and heat transfer.

The temperature drop in hot fluid = the temperature gain by cold fluid

Or, hh Ah (T h,in-T h,o) = hc Ac (T c,in - T c,o)

Different unit processes:

2. How do you represent the process flowsheet/ flow sheet representation of process plants? Explain with one industrial example.

A flowsheet is a part of chemical process design where sufficient information of all the processes and operations are provided in a schematic diagram. Types: a) Block diagram: Simple rectangular box diagrams which give a graphic layout of various steps in a process. Eg.: For a basic bioprocess system, the block diagram is like following:

b) Simplified Engineering Flow-sheets: Visualization of a process in terms of possible physical shape of equipment (symbolic), stram quantities, material and energy balances, instrumentation details and other auxiliary requirements.

c) Detailed Design Flow Sheets: A detailed design flow sheet of complete plant design is the combination of intricate and detailed flow sheets, specifications and details of equipments, detailed piping and electrical layout and plant layout etc.

Industrial example: Lead chamber process with recycle of NO

J. Gay-Lussac (1835) modified the lead chamber process by recovering nitrogen and recycling it. It reduced the use of KNO3. This reduced the consumption and dependence on saltpetre as a source of nitrogen. It made the process more economical and also reduced the impact on the environment. The basic idea can be summarized as follows: nitric oxide was absorbed in water to give nitrous acid. This was reacted with sulphur dioxide to give sulphuric acid, simultaneously releasing the nitric oxide which could be recycled again. In the first reaction, nitric oxide is oxidized and absorbed with water to give nitrous acid. This in turn converts sulphurdioxide to sulphuric acid liberating NO. Thus, we can see that NO consumed in the first reaction is liberated in the second reaction as a product.

4NO O  2 H O  4 HNO 2 2 2

4HNO 2 SO  2 H SO  4 NO 2 2 2 4 The SO2 produced in the sulphur burner is taken to the first column (B). Here it reacts with nitrous acid giving sulphuric acid which is withdrawn from the bottom. The NO released here is absorbed with water to give nitrous acid in the second column (C) which is recycled to the first column.

Schematic representation of NO recycle proposed by Gay-Lusaac. A-Sulphur burner, B-SO2 absorption, C-Nitrous acid production.

3. Explain manufacture of sulphuric acid by lead chamber process with neat flow diagram.

Lead Chamber Process: It was invented by John Roebuck in 1946 and the oldest

method of H2SO4 synthesis. Potassium Nitrate (salt peter) was used as an oxidizing agent to oxidize sulpher to

sulpher trioxide. This used to be absorbed in water to produce H2SO4.

6KNO3 S  7 S  3 K 2 S  4 SO 3  6 NO

4SO3 4 H 2 O 4 H 2 SO 4 . In the original lead chamber process two chemicals, sulphur and potassium nitrate, were mixed and ignited in a room lined with a lead foil. Potassium nitrate or saltpetre was used as an oxidizing agent and it oxidized the sulphur to sulphur trioxide according to the reaction given above. The floor of the room was covered with water. The sulphur trioxide liberated reacted with this water, and sulphuric acid was produced.

The process was essentially a batch process, KNO3 was highly expensive and resulted release of Nitric Oxide which is highly polluting. It also generated potassium sulphide as a waste to be disposed of. Recycle of NO: J. Gay-Lussac (1835) modified the lead chamber process by recovering nitrogen and

recycling it. It reduced the use of KNO3. This reduced the consumption and dependence

on saltpetre as a source of nitrogen. It made the process more economical and also reduced the impact on the environment. The basic idea can be summarized as follows: nitric oxide was absorbed in water to give nitrous acid. This was reacted with sulphur dioxide to give sulphuric acid, simultaneously releasing the nitric oxide which could be recycled again. In the first reaction, nitric oxide is oxidized and absorbed with water to give nitrous acid. This in turn converts sulphurdioxide to sulphuric acid liberating NO. Thus, we can see that NO consumed in the first reaction is liberated in the second reaction as a product.

4NO O2  2 H 2 O  4 HNO 2

4HNO2 2 SO 2  2 H 2 SO 4  4 NO The SO2 produced in the sulphur burner is taken to the first column (B). Here it reacts with nitrous acid giving sulphuric acid which is withdrawn from the bottom. The NO released here is absorbed with water to give nitrous acid in the second column (C) which is recycled to the first column.

Schematic representation of NO recycle proposed by Gay-Lusaac. A-Sulphur burner,

B-SO2 absorption, C-Nitrous acid production.

4. Explain manufacture of sulphuric acid by Contact process with neat flow diagram./ illustrate in detail about the production of sulphuric acid by contact process with neat flowsheet. (April-May 2018)

Contact Process: (wet absorption/DCDA process): Vanadium Pentoxide (V2O5) was

found to be effective in conversion of SO2 to SO3. Sulpher is oxidized to SO3 in a burner

which is further converted to SO3 using V2O5 catalyst pellets in an exothermic reaction at a pressure of 20 atm.

Schematic representation of Contact process for sulphuric acid manufacture. The reactor has three adiabatic beds with intermediate cooling

The gases leaving the last bed contain unreacted sulphur dioxide and trioxide. The SO3 is absorbed in a solution of sulphuric acid. This is necessary since when SO3 is absorbed in water the heat liberated is very high. Further, there is a significant loss in the form of mist which is very corrosive. When it is absorbed in sulphuric acid solution the amount of SO3 absorbed is lower and so the heat liberated during the absorption (heat of absorption) is lower. Here oleum is formed (H2SO4(SO3)).

The formed oleum combines with the aqueous part of the diluted H2SO4 input and forms concentrated sulphuric acid.

DCDA: Double Contact Double Absorption

Due to difficulty in operation with such exothermic reaction the SO3 forming reactor could be divided in 4 beds or stages. Each stage is operated adiabatically so that the gas pass through a stage, the temperature rises. The head generated could be removed by the use of heat exchanger and that heat could be used to generate steam or to move turbine and produce electricity.

The gas leaving bed 3 contains SO3 and unconverted SO2. This gas mixture from bed 3 is sent to absorption tower 1. Diluted H2SO4 (H2SO4 + H2O) solution is also used for absorption.

Finally from absorption tower 1 oleum (H2SO4(SO3)) is obtained.

Excess SO2 from absorption tower 1 is sent back to reactor bed 4 where due to presence of low temperature SO2 get converted to SO3 which is sent to absorption tower 2, to be absorbed with water. Finally, the oleum from absorption tower 1 is sent to absorption tower 2 which altogether get converted to concentrated sulphuric acid as the end product.

This process is used in modern chemical process industries for commercial production of H2SO4. This process is also called wet absorption process and DCDA (Double Contact

Double Absorption Process) of H2SO4 production.

Schematic diagram for Double-contact, double-absorption process for sulphuric acid manufacture

5. Explain manufacture of soda ash by Le-Blanc with neat flow sheet.

Le-blanc Process: In 1791, French chemist Nicolas Leblanc patented this process. First sodium chloride was treated with sulphuric acid to yield sodium sulphate and hydrogen chloride in gaseous state.

22NaCl H2 SO 4  Na 2 SO 4  HCl

Sodium sulphate thus produced was blended with crushed limestone (CaCO3) and Coal (Carbon). This mixture was burnt to produce calcium sulphide and sodium carbonate.

Na2 SO 4 CaCO 3  Na 2 CO 3 2 CO 2  CaS This sodium carbonate was extracted using water and concentrated by evaporation. The hydrochloric acid produced by the Leblanc process was a major source of air pollution, and the solid calcium sulphide by-product also presented waste disposal issues. However, it remained the major production method for sodium carbonate until the late 1880s when the Solvay process was born.

Block diagram for Le-blanc Process process for sodium bicarbonate manufacture

6. Give a detailed note on production of soda ash by Solvey Process with neat flow sheet (April-May 2018).

Solvay Process: In 1861, Belgian Scientist Ernest Solvay developed this method to convert sodium chloride to sodium carbonate using ammonia. The Solvay process is centered around a large hollow carbonation tower as represented in the flow-sheet.

Flow-sheet of Solvay Process for Na2CO3 production

At the bottom of the tower Calcium Carbonate was heated to form Calcium oxide

NaCl NH3  CO 2  H 2 O  NaHCO 3  NH 4 Cl The sodium bicarbonate to sodium carbonate by heating with release of water and carbon- dioxide.

22NaHCO3 NaCO 3  H 2 O  CO 2 Ammonia was regenerated from the byproduct ammonium chloride by treating it with lime

(calcium hydroxide) left over from CO2 generation.

CaO H2 O Ca OH 2

Ca OH2 2 NH4 Cl  CaCl 2  2 NH 3  2 H 2 O . Solvay process only recycles ammonia & consumes only brine and limestone where calcium chloride is the only by-product. This made this process to be substantially more economical than Le-blanc process and soon it started to dominate the global production of soda ash. Because the Solvay process recycles its ammonia, it consumes only brine and limestone, and has calcium chloride as its only waste product. This made it substantially more economical than the Leblanc process, and it soon came to dominate world sodium carbonate production. By 1900, about 90% of sodium carbonate was produced by the

Solvay process, forcing the last plant operating on the Leblanc process to close in the early 1920s.

7. What do you know about the designing of chemical equipments/ Process Eqipment design? Explain it.

Proper design of process equipments is the platform for operation of unit processes to produce high-quality, cost effective design end-product. The design of equipment play a major role in industrial competitions. By the proper design and choice of such equipment, process safety and cost effective production both could be ensured. Some of the few things should be considered while equipment design:- a) Material of Construction (MOC): The choice of material for construction of vessel, reactor or pipeline is based on the material strength, corrosion resistance, elasticity, toughness, ease of fabrication, availability and cost. At the design stage, all possible hazards which are reasonable, that should be listed and the equipment should be checked with critical analysis subjected to those hazards. b) Precaution in design and construction: A properly designed equipment has in-built safety and loss prevention features. Precaution of design and construction include unit reliability and flexibility, ease of operation and maintenance, able to withstand process pressure and temperature. c) Pressure Vessels: For design and construction of pressure vessels and storage tanks, it should be tested at 1.3 times the design pressure. Weld joints and any other flange joints should be leak proof and enough attention has to be provided. d) Heat Transfer Equipment: Choice of insulation should be appropriate and consistent with the material of construction. Allowances should be there due to the stress of thermal expansion. Excessive rate of heat input per unit area should be avoided. e) Electrical Equipments: Special design features are required to prevent ignition of flammable vapor and dust because all electrical installations are inherent sources of ignition. f) Rotating Equipments: The equipment involving rotary motion should be protected by guards. The bearings should be well lubricated and cooled to reduce temperature. g) Use of Pressure relief devices: Use of pressure relief devices are important to maintain / stop excessive liquid/flow, to stop ignition and to avoid the chances of fire hazards. These are maintain valves like:

1. Safety Valve 2. Relief Valve 3. Safety Relief Valve 4. Pressure Relief Valve etc.

7. Write a note on distillation. Explain the process of batch distillation with schematic diagrams and applications.

yyAB/  AB  xxAB/

Where, yA is mole fraction of vapor phase of A, xA is mole fraction of liquid phase of A and yB is mole fraction of vapor phase of B, xB is mole fraction of liquid phase of B

Batch distillation

It refers to the use of distillation in batches, meaning that a mixture is distilled to separate it into its component fractions before the distillation still is again charged with more mixture and the process is repeated. Batch distillation has always been an important part of the production of seasonal, or low capacity and high-purity chemicals. It is a very frequent separation process in the pharmaceutical industry.

Example: Separation of ethanol and water solution. Boiling point of ethanol is 78.37oC and water is 100oC. So if a solution of ethanol and water is boiled, ethanol due to low boiling point comes out or get separated before water. This ethanol vapor could be cooled and condensed to liquid.

8. Explain the process of heat exchange by heat exchanger with schematic diagrams and applications. Based on the flow pattern how it is classified and which is more efficient one?

Such equipment employ both the principles of fluid mechanics and heat transfer.

The temperature drop in hot fluid = the temperature gain by cold fluid

Or, hh Ah (T h,in-T h,o) = hc Ac (T c,in - T c,o)

Counter current flow of heat exchanger is highly favored because high temperature gradient is thoroughly maintained all throughout the length of the heat exchanger. That’s why high exchange of heat occurs throughout the length of it. But in case of parallel flow the heat gradient is highest at the inlet and lowest at the outlet. That’s why the temperature gradient falls to produce reduced energy exchange. This is why the counter current flow mechanism of heat exchange is more efficient than parallel one.

9. Describe the process of crushing and grinding of solid materials with neat sketches and applications.

Crushing: Breaking down the size of large sized ones to smaller sized particles by the use of compressive force. eg.: Jaw crusher, where the crushing is performed in stages using a combination of a jaw, a cone and impact crusher. One jaw is stationary and the other jaw swings front and back due to the rotation of the eccentric. These combined motions compress and push the material through the crushing chamber at a predetermined size..

eg.: Jaw crusher, where the crushing is performed in stages using a combination of a jaw, a cone and impact crusher.

Applications

Jaw crushers are used for primary crushing of a wide variety of materials in the mining, iron and steel and pit and quarry industries. Furthermore they are used in recycling processes.

Grinder: Grinding is performed to get grinded, blended very fine powdery particles by the principles of impact and attrition.

Applications

10. Describe the process of drying of liquid showing two types of dryers with neat sketches and applications.

Spray drying

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. A consistent particle size distribution is a reason for spray drying some industrial products such as catalysts. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen-sensitive then nitrogen is used.

All spray dryers use some type of atomizer or spray nozzle to disperse the liquid or slurry into a controlled drop size spray. A spray dryer takes a liquid stream and separates the solute or

42 suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporized. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximizing heat transfer and the rate of water vaporization. Depending on the process needs, drop sizes from 10 to 500 µm can be achieved with the appropriate choices. The most common applications are in the 100 to 200 µm diameter range. The dry powder is often free-flowing.

Applications:

Food: milk powder, coffee, tea, eggs, cereal, spices, flavorings, blood, starch and starch derivatives, vitamins, enzymes, stevia, nutracutical, colourings, animal feed, etc.

Pharmaceutical: antibiotics, medical ingredients, additives

Industrial: paint pigments, ceramic materials, catalyst supports, microalgae

Vacuum drying

Vacuum drying is the mass transfer operation in which the moisture present in a substance, usually a wet solid, is removed by means of creating a vacuum. In chemical processing industries like food processing, pharmacology, agriculture, and textiles, drying is an essential unit operation to remove moisture. Vacuum drying is generally used for the drying of substances which are hygroscopic and heat sensitive, and is based on the principle of creating a vacuum to decrease the chamber pressure below the vapor pressure of the water, causing it to boil. With the help of vacuum pumps, the pressure is reduced around the substance to be

43 dried. This decreases the boiling point of water inside that product and thereby increases the rate of evaporation significantly. The result is a significantly increased drying rate of the product. The pressure maintained in vacuum drying is generally 0.03–0.06 atm and the boiling point of water is 25-30 °C. The vacuum drying process is a batch operation performed at reduced pressures and lower relative humidity compared to ambient pressure, enabling faster drying.

Applications

Vacuum dryer can be used to dry heat sensitive hygroscopic and toxic materials. If the feed for drying is a solution, it can be dried using vacuum dryer as the solvent can be recovered by condensation. To improve quality of products, such as for fruit preservation, hybrid drying combining osmotic dehydration followed by heat pump drying and microwave-vacuum drying proved effective

11. Describe the working mechanism of open pan evaporator with a diagram.

Open Pan Evaporator

Evaporation is a process for concentrating a solution by vaporizing part or all of the solvent. In most of the cases the solvent is water. The Pan Evaporator set-up is designed to study the fundamentals of evaporation process. The set-up consists of a jacketed pan evaporator made of stainless steel and an electrically heated steam generator of suitable capacity. To evaporate the solution in pan, steam is allowed to enter in the jacket using a control valve. Condensate is collected from steam trap for energy measurement. Tilting is done by a worm gear arrangement to empty the pan.

12. Elucidate the process of Dialysis.

Dialysis works on the principles of the diffusion of solutes and ultrafiltration of fluid across a semi-permeable membrane. Diffusion is a property of substances in water; substances in water tend to move from an area of high concentration to an area of low concentration. Blood flows by one side of a semi-permeable membrane, and a dialysate, or special dialysis fluid, flows by the opposite side. A semipermeable membrane is a thin layer of material that contains holes of various sizes, or pores. Smaller solutes and fluid pass through the membrane, but the membrane blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus.

Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite. The counter-current flow of the blood and dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood. The concentrations of solutes normally found in the urine (for example potassium, phosphorus and urea) are undesirably high in the blood, but low or absent in the dialysis solution, and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to act as a pH buffer to neutralize the metabolic acidosis that is often present in these patients.

13. Describe on agitation of liquids with applications.

 Dispenses a liquid which is immiscible with the other liquid by forming an emulsion or suspension of few drops,  Suspends relatively lighter solid particles,

 Promotes heat transfer between the liquid in the think or container and a coil or jacket surrounding the container,  Blends miscible liquids

Two types of impellers: Radial flow impellers (flow is induced in radial or tangential directions) and Axial flow impellers (currents are parallel to the axis of impeller shaft)

14. Give a detailed note on the following unit operations and their uses: i) Batch distillation, ii) Spray dryer, iii) Open pan evaporator, iv) Dialysis and v) Agitation (April- May 2018) i) Batch distillation:

It refers to the use of distillation in batches, meaning that a mixture is distilled to separate it into its component fractions before the distillation still is again charged with more mixture and the process is repeated. The simplest and most frequently used batch distillation configuration is the batch rectifier, including the alembic and pot still. The batch rectifier consists of a pot (or reboiler), rectifying column, a condenser, some means of splitting off a portion of the condensed vapour (distillate) as reflux, and one or more receivers. The pot is filled with liquid mixture and heated. Vapour flows upwards in the rectifying column and condenses at the top. Usually, the entire condensate is initially returned to the column as reflux.

Use: Batch distillation has always been an important part of the production of seasonal, or low capacity and high-purity chemicals. It is a very frequent separation process in the pharmaceutical industry. ii) Spray dryer:

All spray dryers use some type of atomizer or spray nozzle to disperse the liquid or slurry into a controlled drop size spray. A spray dryer takes a liquid stream and separates the solute or suspension as a solid and the solvent into a vapor. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapor stream and vaporized. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximizing heat transfer and the rate of water vaporization. Depending on the process needs, drop sizes from 10 to 500 µm can be achieved with the appropriate choices. The most common applications are in the 100 to 200 µm diameter range. The dry powder is often free-flowing.

Applications:

Food: milk powder, coffee, tea, eggs, cereal, spices, flavorings, blood, starch and starch derivatives, vitamins, enzymes, stevia, nutracutical, colourings, animal feed, etc.

Pharmaceutical: antibiotics, medical ingredients, additives

Industrial: paint pigments, ceramic materials, catalyst supports, microalgae iii) Open pan evaporator:

Use: Used widely in crystallization and pharmaceutical industries for concentrating aqueous liquids and thermo stable liquors for the purpose of evaporation.

iv) Dialysis

50 dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood. The concentrations of solutes normally found in the urine (for example potassium, phosphorus and urea) are undesirably high in the blood, but low or absent in the dialysis solution, and constant replacement of the dialysate ensures that the concentration of undesired solutes is kept low on this side of the membrane. The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to act as a pH buffer to neutralize the metabolic acidosis that is often present in these patients.

Use: In medicine, dialysis is the process of removing excess water, solutes, and toxins from the blood in people whose kidneys can no longer perform these functions naturally. This is referred to as renal replacement therapy. Hemodialysis is used to remove toxic materials like urea, creatinine etc. v) Agitation of liquids

 Dispenses a liquid which is immiscible with the other liquid by forming an emulsion or suspension of few drops,

 Suspends relatively lighter solid particles,  Promotes heat transfer between the liquid in the think or container and a coil or jacket surrounding the container,  Blends miscible liquids

Two types of impellers: Radial flow impellers (flow is induced in radial or tangential directions) and Axial flow impellers (currents are parallel to the axis of impeller shaft)

14. Illustrate a detailed note on the following processes with their industrial uses: i) Calcination, ii) Combustion, iii) Dehydration, iv) Hydrolysis and v) Nitration, vi) Oxidation and vii) Sulphonation (April-May 2018) i) Calcination:

Calcination is defined as "heating to high temperatures in air or oxygen". However, calcination is also used to mean a thermal treatment process in the absence or limited supply of air or oxygen applied to ores and other solid materials to bring about a thermal decomposition. A calciner is a steel cylinder that rotates inside a heated furnace and performs indirect high- temperature processing (550–1150 °C, or 1000–2100 °F) within a controlled atmosphere.

For example, in limestone calcination, a decomposition process, the chemical reaction is

CaCO3 → CaO + CO2(g) Use: Production of calcium oxide from calcium carbonate. This is highly used in cement industries ii) Combustion:

Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion in a fire produces a flame, and the heat produced can make combustion self-sustaining. It could be seen by burning solid fuels, such as wood and coal or liquid fuels like petrol and diesel.

Wood (Carbon) +O2 → CO2 Hydrogen fuel (H2) +O2 → H2O Use: Energy production in coal fired power plants, fuel combustion car engines iii) Dehydration a dehydration reaction is a conversion that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction. Common dehydrating agents used in organic synthesis include sulfuric acid and alumina. Often dehydration reactions are effected with heating.

Use: The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol in the presence of a dehydrating agent:

RCO2H + R′OH ⇌ RCO2R′ + H2O iv) Hydrolysis

Hydrolysis is a term used for both an electro-chemical process and a biological one. The hydrolysis of water is the separation of water molecules into hydrogen and oxygen atoms (water splitting) using electricity (electrolysis).

Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g. sucrose being broken down into glucose and fructose), this is termed saccharification. Generally, hydrolysis or saccharification is a step in the degradation of a substance.

Use: Sucrose is a disaccharide also known as table sugar. Hydrolysis of this compound results in the creation of two separate monosaccharide sugars known as glucose and fructose. These sugars are used in a variety of applications, widely in the food industry

v) Nitration:

Nitration is a general class of chemical process for the introduction of a nitro group into an organic chemical compound.

Use: There are many major industrial applications of nitration in the strict sense; the most important by volume are for the production of Nitroaromatic compounds such as nitrobenzene. Nitration reactions are notably used for the production of explosives, for example the conversion of of toluene to trinitrotoluene. However, they are of wide importance as chemical intermediates and precursors. vi) Oxidation:

The chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in simple terms:

Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion.

Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.

As an example, during the combustion of wood, oxygen from the air is reduced, gaining electrons from carbon which is oxidized.

Wood (Carbon) +O2 → CO2 Hydrogen fuel (H2) +O2 → H2O Use: such as the oxidation of carbon to yield carbon dioxide (CO2) or the reduction of carbon by hydrogen to yield methane (CH4), and more complex processes such as the oxidation of glucose (C6H12O6) in the human body. vii) Sulphonation

Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution.

Typical conditions involve heating the aromatic compound with sulfuric acid

C6H6 + H2SO4 → C6H5SO3H + H2O Sulfur trioxide or its protonated derivative is the actual electrophile in this electrophilic aromatic substitution. Use: Aryl sulfonic acids are used as detergents, dye, and drugs.

Unit-IV, Part B

1. Explain the role of computers in chemical engineering.

The capabilities provided by computers for fast calculation, large storage, logical decision making and available technical and mathematical tools and softwares permit engineers to solve critical problems more rapidly than manual. A Chemical Engineers emphasis thus got shifted from problem solving to planning, designing, conceiving, interpreting with the solved problems and informations available.  By the development of FORTRAN programming language, chemical engineers got extremely involved for numerical problem solving and mathematical simulation.  One of the most popular design and application for Chemical Engineers is CAD/CAM (Computer Aided Design/Computer Aided Manufacturing), which is concerned with product as object and is much less graphical.  The integration of a system in a chemical/manufacturing/physical process is proper or not could be understood by the use of such process design software workframe.  Design and layout of an overall plant for chemical synthesis, heat exchanger design, selection of pumps and other machineries for flow monitoring based on the specifications could be performed in a smart model. The specifications and dimensions could be changed as per the requirements.  Different chemical engineering flowsheeting softwares like FLOWTRAN, ASPEN PLUS, PROCESS etc. are available by which steady state mass, energy balance, sizing and cost evaluation for a chemical process could be done.  The general technique of computer modeling as applied to chemical processes is called process simulation. This could be used for process design as well as for plant operation and control. A chemical process/unit operation can be represented with mathematical equations which is called mathematical modeling. The model equations could be solved in computers which shows the predictive profile/output of future. This is called simulation. Computers are highly used by chemical engineers for modeling and simulation purposes.  To find the best solution when a large number of operating variables are involved is called optimization. The calculated variable which is maximized (product output) or minimized (production cost) is called objective function or objective variable.

Such process of optimization involves large number of variables, mathematical methods which require computerized simulation environment to produce improvement of objective function.

Relation between simulation and optimization

 Dynamic simulation of online application (value of target variable is dependent on time) process control requires computerized control, inputs and signal to perform desired work. This online signaling extends towards robotics, automatic processes and industrial automation.

Chemical Engineering Software: The Computer Aids for Chemical Engineering (CACHE) made several programmes in USA to generate awareness among Chemical Engineers. Some extremely important and highly used software of Chemical Engineering are:- a) Spreadsheet: Microsoft Excel, Lotus 1-2-3 to analyze data, preparing bar chart, pie chart, graphs. b) Design: CAD/CAM software like Auto CAD and CHEMCAD for process/plant design, numerical simulation for manufacturing process. c) Modeling and Simulation: FORTRAN, MATLAB, PASCAL, C, C++ to analyze energy and mass balances, steady state operations.

57 d) FLOWTRAN simulator of Monsanto Company for flowsheeting is based on FORTRAN Language. CHEMCAD-II, a flowsheeting software provided by Chemistation, Inc. PROCESS is a product of simulation science Inc. ASPEN PLUS by Aspen Technology was developed to handle gas-liquid processes.

2. Relate chemical engineering and other engineering disciplines./ Explain the collaboration of chemical engineering with mechanical, civil and electrical engineering

The purpose of engineering to apply scientific knowledge to practical applications which makes human life easier and comfortable while making it economical. Chemical engineering and other engineering disciplines share cordial relation when it comes about engineering practices and innovations.

 Chemical & Mechanical Engineering: 1. The most common subject is fluid mechanics. Chemical engineers study Heat and mass transfer in depth but that much depth is not provided to Mechanical Engineers. 2. Mechanical Engineers and Chemical Engineers both can deal with equipment design, manufacturing etc. but Chemical Engineers emphasize on process engineering. But in all cases equipment is a common thing because chemical industries deal with a lot of equipment. 3. A Mechanical Engineer will sit at the table listening to a Chemical Engineer layout their pipe schematic and flow patterns but the Mechanical Engineer will think about how many nuts and bolts and bends are required to make it work. Then the Chemical Engineer is going to hope the layout is not going to get cancelled because the Mechanical Engineer is using too many nut bolts. 4. Mechanical Engineers are good in pipe fittings and Chemical Engineers are good in flow profile and dynamics. 5. Mechanical Engineers are good in strength of materials and Chemical Engineers are interested in nature of materials. 6. Mechanical Engineers are good in designing machines and Chemical Engineers are good in designing reactors.

Thus to run a process plant the collaboration of Chemical and Mechanical Engineers is very much required.

Lets take an example of a Car. Mechanical Engineers design, develop car engines and Chemical Engineers produce diesel/petrol in petrochemical plants. Now, if the fuel quality is very low or engine design is poor, the exhaust gas will be highly toxic. Chemical Engineers can suggest it in report that what modifications are required to be made. Thus both of the Engineering streams can take part in air quality management.

 Chemical & Civil Engineering: A Civil Engineer’s role is to organize and execute various construction assignments using the knowledge and skills to construct secure and strong structures. Therefore, analysis of location, site specification and following the guidelines and procedures are important. 1. Design and planning of a chemical/physical/manufacturing process could be done and that project could be executed or not on a selected land area is judged by a Civil Engineer. 2. Moreover, for a Chemical Engineering project, the estimation of land area, housing space requirement for project implementation could be prescribed by Civil Engineers. 3. Civil Engineers work with building materials to construct strong structures. The control or/and improvement of quality of materials (eg.: cement, bricks etc.) are maintained by Chemical Engineers. 4. Both the Civil and Chemical Engineers are interested in reduction of pollution (air, water, land) using appropriate strategies. Though somewhere the approach differs but both the engineering disciplines are putting efforts in water treatment, waste water treatment and waste reduction issues.

5. The biggest common similarity of Chemical and Civil Engineering is towards environmental engineering, a multidisciplinary subject. Both of the engineering streams merge here to keep our environment clean through the pathway of sustainable industrialization. 6. Analysis of sustainability of existing or proposed processes or schemes are performed by researchers of both Chemical and Civil Engineers.

 Chemical & Electrical Engineering: Electrical Engineering is a profession that deal with the study of electrical circuits, flow of electricity, electronics and electromagnetism. 1. Chemical Engineers used to manufacture the circuit materials as per the required specifications of Electrical Engineers. 2. The electrical wire, insulated coating, heat insulation cover, electrically inert materials are industrially manufactured by Chemical Engineers. 3. The most important operating device i.e. switch, made of Bakelite/plastic is supplied by different small/large scale Chemical companies. 4. Chemical Engineers also need to know the specifications and operating principles for pumps, motors and generators which are also part of Electrical Engineering. 5. For proper planning/design and development of a chemical process, knowledge on electrical machines is highly required for Chemical Engineers for cost analysis.

3. Compare traditional and modern chemical engineering.

To clean up the waste generated from existing processes, some waste minimizing techniques or treatment processes are employed which is cleaning technology.  Modern Chemical Engineering is much more inclined in favor of sustainability (meeting the needs of future generation without compromising the needs of present generation) and green process engineering. Previous traditional chemical processes were concerned about the cost of a process but not that much on environment and sustainability. The awareness required a long time to get adopted.  Modern Chemical Engineering is successful in process innovation and integration. By the use of automatic systems, use of mathematical modeling, simulation software and tools, modern chemical plants are more productive without any compromise with product quality.  New age Chemical Engineering has turned out to be a multidisciplinary, and multiscale approach due to the amalgamation of physical-chemistry, environmental awareness, process system engineering, product design and engineering, biological processes. But, traditional Chemical Engineering was only concerned with industrial chemical technologies for production of chemicals. It used to deal mostly with the existing processes with respective troubleshooting. Although, due to progress of age, these requirements were felt, which gave birth to modern Chemical Engineering.  Modern Chemical Engineering is following the principles of green chemistry for efficient production, maximum utilization of resources with maximum production of product and lowest generation of wastes. The principles of Green Chemistry are: 1. Prevention of waste generation 2. Renewable feedstock use 3. Omit derivatization steps 4. Degradable product generation 5. Use of safe method for accident prevention 6. Catalytic reagent 7. Temperature, pressure ambient 8. In process monitoring 9. Very few auxiliary substances 10. E-factor/atom economy 11. Lowest toxicity

12. Yes, it is a safe process.

4. Describe in detail about the role of chemical engineers in food, medical and biochemical industries. (April-May 2018)

Role of chemical engineering in food industry.

Every day we can choose from a broad variety of fresh, safe, wholesome, good-tasting foods to make our meals. We expect our foods to be ready to eat or easy to prepare. For much of this abundance we can credit chemical engineers. Their contributions include:

 Fertilizers, Pesticides and herbicides for growing food

Constant trial-and-error attempts to boost crop size eventually gave way to more focused applications of science and technology. Today synthetic and organic fertilizers significantly increase crop yields, while herbicides and pesticides help protect crops from damage. Thus the overall growth of food supply for human society got increased. Initiation of experiments with such fertilizers and pesticides to soil maximized the yield of their crops.

Most modern fertilizers stem from a chemical-engineering breakthrough pioneered by Fritz Haber in 1908. Haber, a chemist, engineered a process to synthesize ammonia through a reaction between hydrogen and nitrogen.

In addition to developing new, more effective nitrogen fertilizers, chemical engineers are helping protect valuable crops against weeds, insects, and other pests. One such compound is glyphosate, the primary ingredient in Monsanto’s popular herbicide Roundup. It works by inhibiting a specific growth enzyme in plants. When applied to crops, glyphosate is rapidly metabolized by weeds. It also binds tightly to soil, so it does not accumulate in runoff and contaminate surface waters.

 Taste and look

People have always looked for new ways to improve the flavor, texture, and appearance of food. Today an entire branch of chemical engineering is dedicated to applying science and technology to enhance the gustatory and visual appeal of the food we eat.

 Flavour and additives

Chemical engineers have been working closely with food scientists to isolate and produce natural and artificial flavors and other food additives in commercial quantities. The ultimate result has been to create significantly more satisfying dining experiences.

 Natural sweeteners

Refined sugar is produced primarily from sugar cane or sugar beets and has long dominated the natural sweetener market. The commercial-scale production of refined sugar involves a variety of chemical-engineering operations, which include:

Milling shredded raw materials and mixing with water,

Adding chemicals to adjust the pH level to control the acid content,

Removing impurities,

Crystallizing the sugar and drying it, and

Treating wastewater.

In recent years high-fructose corn syrup, made from cornstarch, has been used in foods and beverages. Production of corn syrup also requires many chemical-engineering operations, including:

Dry milling the corn,

Reacting the cornstarch with enzymes, and

Purifying by ion exchange.

High-fructose corn syrup is valued by food processors because it tastes sweeter than refined sugar and is produced as a syrup, which makes it easier to blend into various foods and beverages.

 Artificial sweeteners

Artificial sweeteners are novel chemical molecules that provide a sweetness level 500 to 600 times greater than that of traditional sugar. They are widely valued by calorie-conscious consumers and diabetics who need to limit their sugar intake. The first commercial artificial sweetener was saccharin, discovered in the late 19th century. It is sold under the trade name Sweet’N Low.

 Starches

Starches from various sources are incorporated into processed foods as a major source of nutritional carbohydrates. Starches are also routinely added to foods to act as thickeners, to improve stability, and to provide a good “mouth feel” for the consumer. Chemical engineers have played a key role in effectively isolating the desired starch from cereal grain seeds, roots, and tubers.

 Packaging

Now-a-days the variety of foods available is not limited to only local consumers but also for global people by modern packaging developed by chemical engineers. This enables fresher- tasting, longer-lasting foods like, fruits, seafood, and meat against spoilage and decay. These modern packaging marvels run from basic to high tech and include:

Among the more popular packaging methods being used are sterilization, vacuum packaging, and multilayered packaging.

 Convenience

Prepackaged, frozen, fast-cook, dehydrated, and microwavable foods without compromising the nutritional levels are among the developments that make our fast-paced modern lifestyle more easier. These present-day time-saving conveniences have been brought forward largely through the efforts of the chemical-engineering community.

Role of chemical engineering in medical field.

Over the past half century chemical engineers have made rich and varied contributions to many medical and biomedical advancements in an effort to modernize disease diagnosis and treatment options, improve the safety and efficacy of drug-delivery mechanisms, and achieve better therapeutic outcomes

 Kidney dialysis

Over the past 50 years many pioneering breakthroughs in kidney dialysis have been made by chemical engineers. Often called artificial kidneys, kidney dialysis machines cleanse the blood of impurities. This is one of the treatment techniques used on patients suffering from renal failure (when the two kidneys fail to function). Failure of the kidneys results in the accumulation of toxins like creatinine, urea, and water in the blood stream. It is, hence, necessary to remove these from the blood stream through some artificial means. The principle on which dialysis is based is that of transport of species across a semi-

permeable membrane. The two streams, blood and dialysate (the fluid used to extract the toxins) flow on either side of a membrane. The dialysate consists of a solution of several salts such as chlorides of sodium, magnesium, potassium and calcium, and sodium bicarbonate. The flow is counter current to increase the process (the rate of solute transfer) efficiency. Here the toxins move from the blood to the aqueous phase when the pressure is reduced in the dialysate compartment. The dialyser is typically a rigid cylinder which houses fibres made of a proprietary polymer. The area of the fibres available and the flow rates of the various streams are optimized for efficient solute transfer or extraction. The dialysis unit can be a portable one. The patient is connected to the dialyser till the concentrations of toxins in the blood reduces to acceptable limits. He can then be taken off the dialyser. He is connected to the dialyser again when the concentrations of the toxins in the blood reaches a high value.

 Treating diabetes

To control this chronic disease, patients must test glucose levels in their blood and regularly inject themselves with insulin. Through the combined efforts of chemical engineers, physicians, and biomedical researchers, improved techniques for monitoring blood glucose levels and administering insulin have been developed. For glucose level monitoring, recent innovations include microanalytical techniques that require smaller blood samples, continuous glucose monitors that are implanted beneath the skin, and use of implanted microchips to control insulin addition.

In case of Insulin injection, new advances include automatic, continuous-infusion insulin injection pumps little larger than a cell phone, and compact pens that combine the insulin container with the syringe.

 Antibiotics and tablets

Chemical and pharmaceutical engineers are engaged in developing new drugs and antibiotics to combat the microbial, fungal or viral infections. Thus the average human life is increased than the earlier days while offering strong health and immunity.

In development of tablet and capsules, chemical engineers are working constantly on the shape, size and dosage of drugs that has to be supplied in a medicine. Moreover the coating over the tablets or capsules is an important field of research so that it helps in travelling through body it does not can release the drug but at the specific location and does not harm human/animal bodies.

 Drug Delivery

Historically, the conventional method of delivering medications to patients has been by mouth or injection. Early advancements have included nasal sprays, dermal patches, and controlled-release products. Now, with the help of chemical engineers, targeted drug- delivery vehicles distribute medications directly to the desired location within the body and release it on demand.

Micro medical robots, many shaped like little beetles, are designed to travel inside the body in order to treat infected areas, tissue, or tumor and thus minimize the need for surgery.

Such delivery systems have the advantage of being able to Reduce or delay premature degradation of a drug once it is in the body, Maximize the ability of a drug to travel through the body to the target site without affecting healthy tissue and organs, Minimize the total amount of the drug that must be administered, and Reduce potential side effects that often result when healthy tissue and organs are exposed to a drug.

Role of chemical engineering in biochemical engineering.

Biochemical engineering, a subset of chemical engineering, impacts a broad range of industries, including health care, agriculture, food, enzymes, chemicals, waste treatment, and energy. Biochemical engineering has been central to the development of the biotechnology industry, especially with the need to generate prospective products (often using genetically engineered microorganisms) on scales sufficient for testing, regulatory evaluation, and subsequent sale. The role of chemical engineers could be described in two sub-sections:

 Upstream Production

In biochemical processes the production is mainly dependent on biological resources, biocatalysts (enzymes) and living organisms (microbes/algae/fungi). Chemical engineers work there for

-fermentation reactor (fermentor) development and scale up

-process control, optimization and troubleshooting of pilot plant and commercial scale fermentation processes.

-in use of process control softwares, data analysis, design of experiments, and process modeling application packages.

- in running automated fermentation and quality control

- a chemical engineer will put his efforts for technology transfer, post transfer process optimization, cost of goods reduction, and troubleshooting of manufacturing issues as they arise.

- a chemical engineer can work for chemical products processing, biological systems engineering, food processing technology, bio-fuel, industrial biotechnology, bioreactor design and electrochemical energy conversion

 Downstream processing

For a biochemical process not only product development but also purification of desired product take an important role. The downstream purification or separation of desired product from a mixture of products is necessary for commercialization. This is a complete field of application with research and development following chemical engineering principles. This could be illustrated in four stages:

-Removal of insoluble: capture of the product as a solute in a particulate-free liquid, for the separation of cells or other particulate matter from fermentation broth. Typical operations to achieve this are filtration, centrifugation, sedimentation, precipitation, flocculation, electro-precipitation, and gravity settling.

-Product isolation: removal of those components whose properties vary considerably from that of the desired product. Solvent extraction, adsorption, membrane filtration, and precipitation are some of the unit operations involved.

-Product purification: separation of those contaminants that resemble the product very closely in physical and chemical properties. Unit operations include membrane filtration, size exclusion, reversed phase chromatography, ion-exchange chromatography, crystallization and fractional precipitation.

-Product polishing: the final processing steps which end with packaging of the product in a form that is stable, easily transportable and convenient. Crystallization, membrane filtration, desiccation, lyophilization and spray drying are typical unit operations.

5. Explain in detail about the role of chemical engineering in the area of energy and environment fields. (April-May 2018)

Chemical engineering in the area of energy

Energy and Fuels Engineering is an option in Chemical Engineering. As other chemical engineers do, energy and fuels engineers play an important role in society. They work to safeguard the environment and at the same time provide society with energy technology choices to meet ever-growing needs in areas such as fuel processing and use, and technology development.

 Traditional refining

Crude oil refineries use complex physical and chemical separation and conversion processes to turn crude oil into natural gas, gasoline, diesel and jet fuel, kerosene, lubricating oils, waxes, asphalt and numerous other end products. Some of the important chemical process operations instrumental in modern-day refining include Thermal cracking, Distillation, Fluid catalytic cracking and Hydrocracking.

 Electricity from coal

Coal fueled the Industrial Revolution and for years was the primary power-plant fuel. Chemical engineers have been working to provide greener options for generating electricity from coal. Some power plants now generate power by using coal gasification as an intermediate step instead of coal combustion, with significant environmental benefits.

 Synthetic liquid fuels

In order to reduce our dependence on foreign oil, chemical engineers have been working vigorously to develop, scale up, and commercialize new processes to produce synthetic liquid fuels. Essentially two routes are used to produce synthetic liquid fuels:

The Bergius process, which uses hydrogen and brown or soft coal, and

The Fischer-Tropsch process, which starts with carbon monoxide and hydrogen

 Biofuels

Chemical engineers are involved with developing technologies to convert renewable biomaterials into electricity and transportation fuels, just as they have been with nonrenewable fossil fuels. Waste biomass, corn and sugar are now widely used to

produce ethanol through fermentation, a gasoline substitute. Through transesterification, different vegetable oils (like, soybean oil, jatropha oil etc.) are being used to produce biodiesel fuel.

 Hydrogen fuel

Today use of hydrogen as a fuel has inherent limitations. It is costly to produce and difficult to store and distribute to households and gas stations. Chemical engineers are in the forefront of the race to develop viable processes to produce safe, economical sources of hydrogen and to deliver it where needed.

 Solar and wind energy

To harness the sun's energy chemical engineers are working on development of solar collectors, using the knowledge of material science and heat transfer, in designing the most efficient systems for collecting solar energy and converting it to electricity.

Modern windmill designs are the domain of mechanical and chemical engineers which involves material of constructions, the materials used, sensor and control systems to combat with environmental issues and climate changes.

 Nuclear energy

Nuclear power plants create less air pollution than conventional power plants. But they do produce radioactive products that require long-term confinement storage. Advances spearheaded by chemical engineers have helped improve safety, increase power output, and maximize operating life. Chemical engineers work with nuclear engineers to design, develop, monitor, and operate nuclear power plants in the safest, most efficient manner possible. These scientists are also involved with the production, handling, use, and safe disposal of nuclear fuels.

Role of chemical engineering in global environment.

Chemical engineers meet environmental challenges. Their unique expertise enables them to develop advanced technologies, monitoring devices, modeling techniques, and operating strategies that reduce the volume and toxicity of pollutants allowed to enter the air, waterways, and soil; significantly reduce the negative environmental impact of industrial facilities, power plants, and transportation vehicles; and allow greater reuse of post-consumer and post-industrial waste streams.

 Transportation and the environment

By designing more efficient engines, maintaining and upgrading the fuel quality, that produce fewer hazardous pollutants, chemical engineers have helped reduce the environmental impact of gasoline- and diesel-powered cars, buses, and trucks. The efforts include: improved engines with more efficient fuel- and air-management systems, catalytic devices that destroy pollutants found in exhaust tailpipes, and advanced petroleum-refining techniques that produce cleaner-burning fuels.

 Reducing industrial air pollution

SO2 and NOx react with water to create acid gases, which in turn lead to acid rain. Acid rain damages cars and buildings, kills trees, destroys lakes and streams, and leads to respiratory and other health problems. Chemical engineers developed flue gas desulfurization (FGD), now a widely used method of reducing acid gases in smokestacks. FGD works by using a wet scrubber spray tower in the flue or smokestack. During operation, acid gases are converted to neutral salts and other solid by-products, which are then removed. Solutions to NOx emissions include selective catalytic reduction (SCR) systems that convert NOx emissions to harmless nitrogen gas and water.

 Clean water

Clean water, which is essential to human health, is also necessary for numerous manufacturing processes. Many innovative methods of treating raw water to make it suitable for drinking or for use in manufacturing have been developed by chemical engineers. Chemical engineers refer to separating dangerous materials from good water as a treatment train. At various stages in the multistage treatment process, unwanted constituents are separated using vacuum or pressure filtration, centrifugation, membrane-based separation, distillation, carbon-based and zeolite-based adsorption, and advanced oxidation treatments.

 3R (Reduce, reuse and recycle)

Chemical engineers helps making the industries run with lower consumption of raw materials and fuels without compromising the product quality. Reuse and recycling post-consumer paper, metal, and plastic reduces the environmental impact of acquiring

more raw materials. In manufacturing, reusing industrial waste also offsets raw- material and energy requirements.

 Reducing greenhouse gases

The proper management of Carbon di oxide and other key greenhouse gas (Methane, Nitrous oxide, Hydrofluorocarbons, Perfluorocarbons, and Sulfur hexafluoride) emissions are critical due to global warming. Chemical engineers are at the forefront of efforts to develop and commercialize cost-effective strategies like advanced combustion systems that reduce the formation of GHGs; pollution-control systems engineered to capture CO2 emissions; and generation of cleaner-burning alternative energy sources, such as biomass-derived fuels and solar- and wind-generated power.

6. Explain the role of chemical engineering in electronic industry.

All the extraordinary electronic gadgets and devices that abound in our modern life owe their existence to the semiconductor chip. Providing a source of cheap, fast computing power, these chips are found in everything from children’s toys to phones, automobiles, medical sensors, and communications satellites. Chemical engineers contributed to the invention of semiconductor chips. These versatile scientists are vital in the ongoing development of advanced materials and the manufacturing processes required to produce them. Semiconductors are materials whose ability to conduct electricity lies between that of a conductor and an insulator. Germanium was the first known semiconductor. The present-day industry exploits the semiconducting properties of silicon. Semiconductor chips are shrinking with increase in their data capacity, where the ingenuity and creativity of chemical engineers could be seen.

-Chemical engineers are involved in developing new materials and coming up with suitable processes for chip manufacturing.

- Here chemical engineering principles like chemical kinetics, fluid mechanics and transport phenomena are used. More than a few hundred steps are involved in creating a chip from the silicon wafer.

-Of these, chemical engineers play a major role in developing and implementing deposition (chemical vapour deposition, electrochemical deposition, spin-on coating), removal of excess materials (wet etching, dry etching or plasma etching, chemical

71 mechanical planarization), cleaning (removal of contaminants from the wafer using hydrofluoric acid, ammonia, hydrogen peroxide) and material modification (oxidation of silicon to silicon dioxide using oxygen or steam, diffusion of boron or phosphorous in silicon to form different types of semiconductors).

- In chemical vapour deposition (CVD), the reaction is carried out using vapour phase reactants while the desired product is formed on the wafer, in the solid phase.

- Copper wires are used to connect the transistors. Cu is deposited in very thin wires, with thickness of the order of 100 nm, using electrochemical deposition

- For creating insulating materials around the copper wires, organic films are dissolved in a solvent which is poured on the wafer. A thin layer of the solution is formed on the wafer by rotating the wafer with the solution on the top. The solvent evaporates leaving the organic coating. This technique is called spin-on coating.

- To remove the excess materials, etching process is performed by applying suitable chemicals. For example, to remove silicon dioxide, Hydrogen Fluoride is used, whereas to remove silicon nitride without affecting the silicon dioxide, hot phosphoric acid is used. Based on the property of material, process of wet etching and dry etching (reactants in gas phase, along with plasma created by a high voltage are used) could be used.

- The silicon material is converted into different types of semiconductors by adding small quantities of materials called dopants. If boron is added to Si, the silicon is called P-type silicon and if phosphorous is added, it is called N-type silicon. Addition of such dopants for material modification is called ion implantation which enhances the charge carrying features through semiconductor material.

-The entire processing of these chips is done in clean rooms. These rooms have strict specifications such as one particle in a cubic foot. If a dust particle is lodged in a circuit, then it would completely damage it since it would obstruct the pathway of current. Chemical engineers design the clean rooms by designing filtration systems to capture chemical vapours, microbes, and dust particles.

Unit-V

1. What are the different paradigms in chemical engineering? Explain on the paradigm shifts in Chemical Engineering.

The chemical engineering development is guided by its four main paradigms: unit operations, transport phenomena, product engineering and sustainable chemical engineering.

Paradigm means a typical example or pattern of something; a pattern or model. The starting point is the paradigm definition as “a set of assumptions, concepts, values, and practices that constitutes a way of viewing reality for the community that shares them, especially in an intellectual discipline”.

The developed new technologies are required to become much more eco-friendly with less feed material and energy consuming while giving the same or higher product output. Generation of wastes are aimed to be minimized (clean technologies) or if the waste are getting formed there has to be efficient cleaning technology confirming zero discharge (cleaning technologies).

 The chemical engineering development is guided by its four main paradigms: unit operations, transport phenomena, product engineering and sustainable chemical engineering.

 Related to the paradigms role in the evolution of chemical engineering, it is relevant that even when paradigms are known to be inadequate, their inadequacies are frequently minimized, or even ignored by the scientific community.

 Nevertheless, if and when a paradigm reaches a crisis where its technical inadequacies are brought into focus, perhaps driven by social requirements, a new paradigm will arise to explain what the prior paradigm could not.

 During the evolution of chemical engineering, from its beginning at the end of 19th century up today’s, each new paradigm was a step forward to solve the difficulties. In fact, almost all paradigms must be used together in order to solve the complex chemical engineering problems.

 Due to the strict environmental regulations all over the world, the chemical, pharmaceutical and allied process industries are witnessing paradigm shift in their production strategy from the use of high temperature and high pressure processes to environment-friendly green technologies.

 Sustainability is defined as “Meeting the needs of future generation without compromising the needs of the present generation”. Embracing the concepts of sustainable technology and sustainable development all currently practiced energy-intensive and polluting processes and technologies will have to eventually leave space for green production technologies.

 New generation or next-gen production strategies that encourage clean production in more efficient, more energy-saving, compact, flexible yet small plant configuration in other words is termed process intensification (PI)

 Chemical and allied process industries are shifting towards clean technology and cleaning technologies to confirm sustainability through such process intensification.

2. Explain on the range of scales in Chemical Engineering.

Typically, the job of a chemical engineer is to generate chemical products in bulk amount in industries. The term, “Scale of production” refers to the size of the production unit of a firm or business. Depending on the size of production, it can be classified into large scale and small scale production.

Generally, three scales are considered based on the range of product output: Bench scale (lab scale), Pilot scale and Industrial scale (commercial scale).

Before making a process commercialized for production of a target product, first the bench scale operation is performed in lab to check the validity of the idea. Then after cost evaluation, the process is developed for pilot scale to check the performance and selectivity of the developed system towards the target product. Finally, if the pilot scale testing live successful then the process is considered for commercialization at a full scale to generate the desired product.

1. Bench scale (lab scale): a designed process or a product is first produced in very small scale in laboratory. From here, the researcher gets an idea that the adopted process is suitable for production of desired product or not. If the experimentation live successful and all the desirability are met, then cost evaluation for the same process should be conducted and the same operation should be conducted in pilot scale.

2. Pilot scale: A pilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology.

The knowledge obtained is then used for design of full-scale production systems and commercial products, as well as for identification of further research objectives and support of investment decisions. Other (non-technical) purposes include gaining public support for new technologies and questioning government regulations.

Pilot plant is a relative term in the sense that pilot plants are typically smaller than full-scale production plants, but are built in a range of sizes. In the pharmaceutical industry for example, bench

scale is typically conducted on samples 1–20 kg or less, whereas pilot scale testing is performed with samples of 20–100 kg.

3. Industrial scale (commercial scale/ Large scale):

It refers to the production of a commodity on a large scale with a large sized firm. It requires huge investments in plant and machinery. Large scale production can be carried out if the market size is large and expanding.

Lab Scale (bench scale) Pilot scale Industrial production

Cost of same equipment of higher capacity could be calculated using the standard equation:

n capacity of high capacity equipment Cost of higher capacity equipment = Cost of lab scale equipment ×  capacity of lab scale equipment where, n represents the scale-up factor and differs for different equipment.

3. Write in detail about the job opportunities in chemical engineering field./ Write in detail about the opportunities of chemical engineering. (April- May 2018)

Chemical engineers use science and math to take ideas and turn them into products in a cost effective and safe manner. Chemical engineers work in areas such as chemicals, biotechnology, pharmaceuticals, food, energy, environment, consumer products, electronics, nanotechnology, advanced materials, and finance. Chemical engineers have jobs in research, design, development, manufacturing, optimization, teaching, and consulting. Chemical engineers work in laboratories, plants, and offices. Chemical engineers by satisfying their own roles and applying new research and innovations can enrich the respective job fields in the following areas:

 process engineering and control

 production supervision

 economical process analysis

 product quality control

 process validation

 pollution control

 health and safety aspects of manufacturing practises 84

 computer-assisted design

Opportunities for Chemical Engineers are in diversified fields like:-

a) Bioprocess : Biological production of food, drinks and Engineering pharmaceuticals eg: production of Insulin from E.Coli.

b) Chemical : Chemical processing Technology for production of processing fertilizer, pesticide, herbicides, caustic soda, glass, specially chemicals.

c) Combustion : Recovery of energy from coal/natural/renewable resources to energy.

d) Environmental : Water & waste water treatment, environmental regulation, recovery & reuse of valuable material.

e) Mineral : Processing of ores like copper, lead, gold.

f) Petroleum & : Conversion of natural gas and oil to fuel, synthetic petrochemicals rubber and LPG, plastics.

g) Project : Conversion of a process plant to a safe an efficient Delivery one to run the process run smoothly and safely.

h) Research & : Development of new product/process integration in Development lab,. Evaluation of production cost and commercial implementation after patenting. Organizing workshops/conference for spreading knowledge in other people.

4. What do you think about the future of chemical engineering? Explore your view in detail./ Illustrate in detail about the future of chemical engineering. (April- May 2018)

The future of chemical engineering can be summarized by four main objectives:

(1) Increase productivity and selectivity through intensification of intelligent operations and a multiscale approach to process control;

(2) Novel design equipment based on scientific principles and new production methods: process intensification;

(3) Extended chemical engineering methodology to product design and product focussed processing using the 3P Engineering “molecular Processes-Product-Process” approach;

(4) Implemented multiscale application of computational chemical engineering modelling and simulation to real-life situations from the molecular scale to the production scale.

Chemical Engineering is vital for sustainability: to satisfy, both, the market requirements for specific end-use properties of products and the social and environmental constraints of industrial-scale processes. A multidisciplinary, multiscale approach to chemical engineering is evolving due to breakthroughs in molecular modelling, scientific instrumentation and related signal processing and powerful computational tools.

The broader future for chemical engineering:

1. Space Fuel Processing for Space shuttle to make it less costly and long lasting. Chemical engineers are currently working to find new sources for fuels e.g. bio-refineries, wind farms, hydrogen cells, algae factories and fusion technology. These could be applied to fuel space travel.

2. Nuclear Recycling like uranium recyclers, will be needed for use in nuclear power plants to ensure that the uranium shortage does not cause an energy crisis.

3. Genetic Farming could be the option for future to raise livestock and agricultural crops to solve food problems. Growth of therapeutic proteins, pharmaceuticals and chemicals based on bioproducts are showing new directions to future of chemical engineers.

4. Nano-manufacturing of catalyst, chemicals, nanorobots for production, reaction and medical purposes.

5. Smart city projects has already started to grow with proper infrastructure of water recycle, use of alternate energy resources and cycle economy where chemical engineers can contribute in each section of their expertise.

6. Simplicity in production process and plant design for both upstream and downstream processes paves the pathway towards future. Chemical engineers, who excel at math, have an eye for design and a keen sense of planning will do well in this line of work.

7. Green Process Engineer

Achievements in sustainable technology, water management and energy efficiency, chemical engineers being the Green process engineers will develop environmentally benign chemical processes and products. They will select processes that minimise pollution, use less hazardous materials and develop alternative reactions while meeting emerging regulations and laws.

8. Climate Change Reversal Engineer

As the threats and impacts of climate change increase and manifest further, a new breed of chemical engineers will be needed to help reduce and reverse the effects of climate change. They will need to be able to apply multi-disciplinary solutions to solve a range of problems.