DOCSLIB.ORG

Recovery Boiler Capability to Accommodate Alternative Kraft Mill Processes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Recovery Boiler Capability to Accommodate Alternative Kraft Mill Processes P I Recovery Boiler Capability to Accommodate Alternative Kraft Mill Processes John I.. Clement Manage6 Pulp and Paper lndus try Marketing The Babcock & Wilcox Company Barberton, Ohio 1. he Technical Association of the Pulp and The kraft process starts with feeding wood Paper Industry (TAPPI) sponsored a Paper In- chips to the digester. Chips are cooked under pres- Tdustry Research Needs workshop at the State sure in a steam heated aqueous solution of sodium University of New York, College of Environmental hydroxide (NaOH) and sodium sulfide (Na2S) Science and Forestry in Syracuse, New York, May known as white liquor, or cooking liquor. Cooking 26-28,1992, The Pulping and Bleaching Processes can take place in continuous or batch digesters. Panel identified the major need in kraft black liquor After cooking, pulp is separated from the residual recovery, namely, an affordable, incremental, liquor in a process known as brown stock washing. chemical recovery capacity increase to remove the The most common method in use features a bottleneck in the recovery boiler operation. This countercurrent series of vacuum drum washers to paper will explor? kraft mill process factors that displace the liquor with minimum dilution. cause a pulp producer to require more capacity. Modern continuous digester installations incor- Approaches to removing the bottleneck and porate a brown stock washing stage in the lower providing increased black liquor processing part of the digester body. Following washing, the capability include retrofitting the existing recovery pulp is screened and cleaned to remove knots and boiler to increase its capacity. Retrofit case histories shives and to produce pulp for use in the final pulp were selected from an extensive list of retrofit ex- and paper products. Currently, industry is focused perience to represent a spectrum of possible ap- on maximizing washing efficiency to recover proaches. chemicals, thereby reducing the chemical demand in the bleach plant. Kraft Process and the The black liquor rinsed from the pulp in the Recovery Boiler washers is an aqueous solution containing wood lignins, organic ' material, and inorganic com- The kraft process diagram (Fig. 1) shows the typical pounds oxidized during the cooking process. Typi- relationship of the recovery boiler to the overall cally, the combined organic and inorganic pulp mill operation. The primary function of a compounds are present at a 13 to 17 percent con- recovery boiler is to combust the black liquor centration of solids in weak black liquor. The kraft produced in the pulping operation for the purpose cycle processes this black liquor through a series of recovering the .inorganic chemicals in the operations, including evaporation, combustion reduced form required for recycling to the digester. organic materials, reduction of the spent inorgan1 The heat content of the black liquor is recovered as compounds, and reconstitution of the white liqu steam for process heat and cogeneration electrical The recovery boiler furnace (Fig. 2) production. Electrical production is a secondary developed to combust the black liquor organ1 function, but an important economic considera- material while reducing the oxidized inorgan1 tion. material in a pile, or bed, on the furnace floor. fi 66 '. I J.L. CLEMENT Figure 1.Yraft process diagram. molten inorganic chemicals, or smelt, are dis- tario Ministry of the Environment, which describes charged to a tank in which they are dissolved to the impact on the recovery boiler throughput of al- form green liquor. The active chemicals in green ternative kraft mill processes (N. McCubbin Con- liquor are sodium carbonate (Na2C03) and Na2S. sultants, 1992). Several processes have been Green liquor is clarified to remove insoluble developed to extend delignification of the kraft material, then reacted with lime (CaO) in a caus- pulps beyond the conventional levels. This exten- ticiting plant to convert Na2CO3 to active NaOH sion is environmentally desirable in circumstances in the product white liquor. in which the pulp will be bleached in subsequent Energy is released as the black liquor organic processes. "Extended delignification'' is also known compounds are combusted, paralleling the reduc- as "extended cooking." Delignification by oxygen, tion of sulfur compounds to form smelt in the extended cooking, and improved brown stock recovery furnace. This . combustion energy washing and screening can produce up to 12 per- produces steam, which can be introduced to a tur- cent additional black liquor solids in a mill that has bine generator to supply a large portion of the ener- relatively high losses of black liquor solids in the gy demand of the pulp and paper mill. Steam sewer. In mills that already have good washing, extracted from the turbine at low pressure is reused defined as sodium losses under 10 kg of sodium in the process for cooking wood chips, evapora- sulfate (Na2S04) per ton of pulp, the additional tion, recovery furnace air heating, and drying the recovery load would be about 6 percent. pulp or paper products. If the alternative processes are considered inde- pendently, oxygen delignification increases the Impact of Alternative solid flow to the recovery boiler about 4.4 percent, Manufacturing Processes which represents a 3.3 percent increase in heat input. Applying extended cooking would increase Alternative kraft mill processes are increasing the the solids to the recovery boiler approximately 3 quantity of organic and inorganic material in the percent when the bleached yield of pulp from black liquor that must be processed in the recovery wood is maintained. The alternative of combining boiler. Therefore, additional incremental capacity both oxygen delignification and digesterextended is required to recover the inorganic chemicals. In delignification, as well as efficient washing, could many mills, this capability is limited by the installed result in a drop in the yield of bleached pulp from equipment. wood, with corresponding increases in wood con- Values for the increased capacity requirements sumption and steam production. The combined are quoted from a 1992 reDort DreDared for the On- changes to a mill operating with high losses could Figure 2.-Typical modern recovery boiler. result in a 15 percent increase in solids to the only about 25 percent of the by-product acid can recovery boiler and a 16 percent increase in'heat be used. The excess must be neutralized before input. being discharged to the sewer; this effect is geheral- Chlorine dioxide (C102) is used increasingly to ly accomplished with lime. replace the traditional chlorine in the first stage of the bleach plant. C102 substitution is a simple ap- proach to reducing organochlorines discharged Recovery Boiler Capacity from the mill. C102 is always manufactured on the kraft mill's site since it is impractical to transport There are several ways to increase the recovery significant quantities. The C102 plant is linked with boiler capacity by 6 to 15 percent generally re- the recovery process since the manufacturing quired by the combined application of oxygen process produces significant quantities of sodium- delignification, extended cooking, efficient wah- I based by-product acid. It is general practice to ing, and similar processes. Incremental capacity in- i blend the effluent acid from the C102 generator into creases can also be measured in several ways. It weak black liquor at a rate equivalent to the total can be an increase in the time between shutdowns $1 sodium losses in the mill. In a modern mill with low to waterwash the recovery boiler, or, the capability 'I sodium losses and practicing 100 percent substitu- to burn more black liquor without increasing the 1 tion to produce a molecular chlorine free pulp, time (run campaign) between outages. 1.L. CLEMENT ~ The most significant limiting factor to increased must be totally removed and the boiler cooled. recovery capacity is ash buildup on the boiler heat Total smelt bed removal precludes a possibility of transfer surfaces (Fig. 3). Low melting point, inor- water contacting molten chemical in the bed and ganic ash compounds formed in combustion of producing a smelt water reaction. Interruption in black liquor are borne upward by the gases in the operation for one to two days for waterwashing furnace and stick to the surface of the tubes. As the represents a potential loss in pulp production, or al- black liquor throughput is increased, the increased ternatively, continuing pulp mill production by temperature and velocity of the combustion gases shipping black liquor to an alternate mill site for increase the propensity of ash to stick and block the burning, and purchasing the lost electrical genera- gas passages. Ash is cleaned from tube surfaces tion from the utility. Downtime is an expensive using jets of steam introduced through sootblowers. proposition! Even with sootblowers in constant use to clean Therefore, the operator requiring additional surfaces, the operator has no alternative but to shut capacity to process black liquor solids has two down the boiler periodically and waterwash the basic approaches to consider. The first is to add an tube surfaces. To accomplish this, the smelt bed additional recovery equipment line to process the solids. Alternatives to adding more lines are the focus of development projects. One al- ternative, a black liquor gasifica- tion unit installed at Frovifors in Sweden, is reported to have operated commercially for half a year (Bostrom and Hillstrom, 1992). The purpose of the instal- lation was to increase the recovery boiler capacity by 75 to 100 tons of dry solids per day, corresponding approximately to an 8 to 10 percent increase in the capacity of the existing recovery boiler. Another solution to adding more lines is being developed by MTCl and ThermoChem and is based on pulse-assisted fluid bed gasification technology for indirect gasification of black liq- uor (Mansour et al. 1992). A design is reported to be under way of a 72 to 100 wet ton per day gasifier for demonstration testing at a southeastern mill.
Load more

Recommended publications
  • Entrained-Flow Gasification of Black Liquor and Pyrolysis Oil
    LICENTIATE T H E SIS Department of Engineering Sciences and Mathematics Division of Energy Science Yawer Jafri Entrained-Flow Gasification of Black Liquor and Pyrolysis Gasification of Black Liquor and Pyrolysis Jafri Entrained-Flow Yawer ISSN 1402-1757 Entrained-Flow Gasification of ISBN 978-91-7583-761-1 (print) ISBN 978-91-7583-762-8 (pdf) Black Liquor and Pyrolysis Oil Luleå University of Technology 2016 Pilot-Scale and Equilibrium Modelling Studies of Catalytic Co-gasification Yawer Jafri Energy Engineering Licentiate Thesis Entrained-Flow Gasification of Black Liquor and Pyrolysis Oil Pilot-scale and Equilibrium Modelling Studies of Catalytic Co-gasification Yawer Jafri Energy Engineering Division of Energy Science Department of Environmental Sciences and Mathematics Luleå University of Technology a Printed by Luleå University of Technology, Graphic Production 2016 ISSN 1402-1757 ISBN 978-91-7583-761-1 (print) ISBN 978-91-7583-762-8 (pdf) Luleå 2016 www.ltu.se b Abstract The last couple of decades have seen entrained-flow gasification of black liquor (BL) undergo an incremental process of technical development as an alternative to combustion in a recovery boiler. The ability of the technology to combine chemical recovery with the production of clean syngas renders it a promising candidate for the transformation of chemical pulp mills into integrated forest biorefineries. However, techno-economic assessments have shown that blending BL with the more easily transportable pyrolysis oil (PO) can not only increase the energy efficiency of the conversion process for methanol production, but also remove a significant roadblock to commercial deployment by partially decoupling production capacity from BL availability.
    [Show full text]
  • TECHNICAL REPORT – PATENT ANALYSIS Enhancing Productivity in the Indian Paper and Pulp Sector
    TECHNICAL REPORT – PATENT ANALYSIS Enhancing Productivity in the Indian Paper and Pulp Sector 2018 TABLE OF contEnts ACKNOWLEDGEMENTS 10 EXECUTIVE SUMMARY 11 1 INTRODUCTION 13 2 OVERVIEW OF THE PULP AND PAPER SECTOR 15 2.1. Status of the Indian Paper Industry 15 2.2. Overview of the Pulp and Papermaking Process 20 2.3. Patenting in the Paper and Pulp Industry: A Historical Perspective 22 2.4. Environmental Impact of the Pulp and Paper Industry 25 3 METHODOLOGY 27 3.1. Search Strategy 27 4 ANALYSIS OF PATENT DOCUMENTS USING GPI 31 4.1. Papermaking; Production of Cellulose (IPC or CPC class D21) 31 4.2. Analysis of Patenting Activity in Different Technology Areas using GPI 38 5 ANALYSIS OF THE INDIAN PATENT SCENARIO WITHIN THE CONTEXT OF THIS REPORT 81 5.1. Analysis of Patents Filed in India 81 6 CONCLUDING REMARKS 91 REFERENCES 93 ANNEXURE 94 Annexure 1. Technologies related to paper manufacturing 94 Annexure 2. Sustainable/green technologies related to pulp and paper sector 119 Annexure 3. Emerging Technology Areas 127 List OF FIGURES Figure 2.1: Geographical Spread of Figure 4.11: (d) Applicant vs. Date of Indian Paper Mills .................................16 Priority Graph: Paper-Making Machines Figure 2.2: Share of Different Segments and Methods ........................................42 in Total Paper Production .......................19 Figure 4.11: (e) Applicant vs. Date of Figure 2.3: Variety Wise Production of Priority Graph: Calendars and Accessories ..43 Paper from Different Raw Materials ........19 Figure 4.11: (f) Applicant vs. Date of Figure 2.4: Different Varieties of Paper Priority Graph: Pulp or Paper Comprising Made from Various Raw Materials ..........19 Synthetic Cellulose or Non-Cellulose Fibres ..43 Figure 2.5: Diagram of a Process Block Figure 4.11: (g) Applicant vs.
    [Show full text]
  • XXL Size Recovery Boilers – Present Status and Future Prospects
    Published May 24, 2017 XXL Recovery Boilers XXL size recovery boilers – present status and future prospects Executive Summary XXL size recovery boilers have operated since 2004, when the first XXL size recovery boiler started up in China. From the process point of view, those boilers have run extremely well, either reaching or exceeding all process requirements. The XXL size recovery boilers are typically designed for high dry solids content, high energy efficiency, low air emissions, and environmentally friendly process solutions. Those boilers burn Non-Condensable Gases (NCG) and other side streams coming from the other parts of the mill, and therefore the XXL size recovery boilers are very important in targeting for odorless pulp mills. However, some units have encountered mechanical problems after start-up due to the large size of certain components in the pressure part. However, all those challenges have been solved and these experiences have helped to develop boilers further toward even safer operation and higher availability. In the future, larger and larger recovery boilers will be built; therefore development work is still needed to reach even lower emissions and better availability. New recovery boilers are very typically planned to operate for at least 18 months. This creates challenges for the engineering of many process systems and components in order to meet the requirements for safety and process optimization. However, long experience with XXL size recovery boilers helps meet these new demands for longer operation periods. © Valmet Page | 1 Published May 24, 2017 XXL Recovery Boilers Introduction Large recovery boilers producing bioenergy have been built all over the world.
    [Show full text]
  • Systematic Review on Isolation Processes for Technical Lignin
    processes Review Systematic Review on Isolation Processes for Technical Lignin Marlene Kienberger *, Silvia Maitz, Thomas Pichler and Paul Demmelmayer Institute of Chemical Engineering and Environmental Technology, Graz University of Technology, Inffeldgasse 25c, A-8010 Graz, Austria; [email protected] (S.M.); [email protected] (T.P.); [email protected] (P.D.) * Correspondence: [email protected]; Tel.: +43-031-6873-7484 Abstract: Technologies for the isolation of lignin from pulping process streams are reviewed in this article. Based on published data, the WestVaco process, the LignoBoost process, the LigoForce SystemTM and the SLRP process are reviewed and discussed for the isolation of lignin from Kraft black liquor. The three new processes that have now joined the WestVaco process are compared from the perspective of product quality. Further, isolation processes of lignosulfonates from spent sulfite liquor are reviewed. The limitation for this review is that data are only available from lab scale and pilot scale experiments and not from industrial processes. Key output of this paper is a technology summary of the state of the art processes for technical lignins, showing the pros and cons of each process. Keywords: Kraft lignin; lignosulfonates; lignin isolation processes; technical lignin 1. Introduction Citation: Kienberger, M.; Maitz, S.; After cellulose, lignin is the second most abundant biopolymer worldwide. Lignins are Pichler, T.; Demmelmayer, P. non-toxic and renewable, and hence may play an essential role during the change-over from Systematic Review on Isolation a fossil-based to a bio-based economy. The value-added application of technical lignin not Processes for Technical Lignin.
    [Show full text]
  • Energy Generation and Use in the Kraft Pulp Industry
    ENERGY GENERAnON AND USE IN THE KRAFT PULP INDUSTRY Alex Orr, H.A.Simoos Ltd INTRODUCTION The pulp and paper industry is one of the largest users of energy among the process industries, but most of its requirements, both steam and electrical power, can be produced from by-product and waste material produced within the process. This paper will discuss energy utilisation and generation in kraft pulp mills, and briefly describe the basic kraft pulping process. THE KRAFT PROCESS The kraft process is the most widely used chemical pulping process for a number of reasons: it produces the strongest pulp; it can handle a wide range of furnish: softwood, hardwood, bagasse and bamboo; the cooking chemicals can be recovered economically; it is energy efficient Figure 1 shows a simplified schematic of a kraft mill. The wood furnish supplied to the mill can be in the form of logs (roundwood) or by-product chips from sawmills.. The source of the wood supply has a significant affect on the energy production.. Ifroundwood is chipped the waste wood produced per ton ofchips will be around 200 kg, but when sawmill by-product chips are used the waste wood produced in the sawmill will be in the range of 450 kg/ton chips, as most of the log goes to produce lumbero This waste wood may be available to the pulp mill at a low cost, or even negative cost, allowing the production of low cost steam and electrical power" The chips are mixed with white liquor (NaOH and N~S) and cooked, using steam, in a large pressure vessel called a digester, either in a continuous or batch process.
    [Show full text]
  • A-RECOVERY+ CHEMICAL RECOVERY SOLUTION A-Recovery+ Chemical TABLE of CONTENTS Recovery Solution: New Opportunities in Kraft Mills
    SEE THE CHEMICAL CYCLE IN A NEW LIGHT A-RECOVERY+ CHEMICAL RECOVERY SOLUTION A-Recovery+ chemical TABLE OF CONTENTS recovery solution: new opportunities in kraft mills A-RECOVERY+ CHEMICAL SULFURIC ACID With the goal of operating chemical recovery systems in a way that is as effi- RECOVERY SOLUTION PRODUCTION cient and and environmentally sound as possible, while minimizing capital and The next generation solution Production of concentrated operating expenses, A-Recovery+ chemical recovery solutions from ANDRITZ for the chemical recovery commercial-grade sulfuric cycle of pulp mills. acid in the mill can lead to offer new opportunities for kraft mills. significant savings. Over the years, chemical recovery loops have been “closed” to reduce emissions METHANOL LIGNIN RECOVERY and effluents – and to increase recov- PURIFICATION Production of high- ery efficiency. These closures some- Raw methanol is purified to a quality lignin on site can times resulted in an overabundance of merchantable bio-methanol. debottleneck a recovery certain chemicals in the chemical cycle boiler and reduce the cost and sometimes created side streams or of purchased fossil fuels or waste streams that were either disposed generate additional revenue of or ignored. by selling bioproducts. BENEFITS OF A-RECOVERY+ SOLUTIONS • Environmental and economic savings • Further closure of chemical recovery loops • Management and control of sodium/sulfur (Na/S) balance • Generation of key chemicals avoids purchasing costs • Additional opportunities for revenue generation • Removes obstacles to fossil-free operation 2 3 SEEING CHEMICAL RECOVERY IN A NEW LIGHT ANDRITZ has taken a fresh look at chemical recovery and developed technical solutions called “A-Recovery+”. This shines a new light by further closing the chemical cycle and converting side streams.
    [Show full text]
  • High Power Generation from Recovery Boilers
    Published October 25, 2015 High Power Generation from Recovery Boilers High Power Generation from Recovery Boilers - What Are the Limits? Executive Summary Increasing power generation from recovery boilers has been an item of interest since 2000 and really became a strong driver in the last 5 to 10 years. This trend came partly from the pulp and paper (P&P) industry desire to increase efficiency and reduce cost, but also from the legislative authorities' desire to reduce Green House Gas (GHG) emissions and their role in climate change. Current European Union (EU) legislation gives strict limits on how much electrical power consumption of each member country must come from renewable sources by the year 2020. Since the P&P industry represents, especially in Nordic countries, a large portion of the energy generation and consumption, companies are trying to take full benefits of the available financial incentives for renewable electrical power generation and improve their environmental image by minimizing fossil fuel usage. Although current prices for fossil fuel are coming down*, mostly due to shale oil and gas increased production, the demand for increased energy efficiency in pulp mills is a key factor in new recovery boiler projects around the world, with the goal to minimized energy purchase and maximize in-house power generation, often with the goal to generate revenue by selling excess green energy. (* Note: This paper was written in mid-2015. The Äänekoski mill is scheduled to come online in late 2017.) © Valmet Page | 1 Published October 25, 2015 High Power Generation from Recovery Boilers Introduction So, where are we with the technology? The discussion with recovery boilers has traditionally been around the maximum achievable steam parameters (temperature and pressure).
    [Show full text]
  • Organosolv Pulping of Wheat Straw by Glycerol
    CELLULOSE CHEMISTRY AND TECHNOLOGY ORGANOSOLV PULPING OF WHEAT STRAW BY GLYCEROL E. SABERIKHAH, J. MOHAMMADI ROVSHANDEH* and P. REZAYATI-CHARANI** Department of Chemistry, Faculty of Science, Islamic Azad University of Rasht, Gilan, Iran *Caspian Faculty of Engineering, University College of Engineering, University of Tehran, Rezvanshahr, Gilan, Iran **Department of Pulp and Paper Technology, Faculty of Forestry and Wood Technology, Gorgan University of Agriculture and Natural Resources, Gorgan, Iran Received May 6, 2010 Pulping of wheat straw was studied with an organic solvent (glycerol) and 2% NaOH as a catalyst, and without catalyst, at various cooking times (180, 90, 45 and 30 min), and at reflux temperature (195-205 °C) as cooking temperature, to investigate the properties of the obtained pulp (cooking yield, kappa number, freeness (CSF), fiber length, α-cellulose, γ-cellulose, ash) and paper (breaking length, burst index, fold endurance, tear index). The best properties of the handsheets were obtained with 2% sodium hydroxide in the cooking solvent, at 30 min as cooking time. As a result of using the processing variables over the variation ranges considered, the following optimum values of the dependent variables were obtained: 64.1% (yield), 64 (kappa number), 300 mL CSF (freeness), 11.89 km (breaking length), 60.38 (folding endurance), 9.27 mNm2g-1 (tear index) and 4.60 kNg-1 (burst index) for pulps and handsheets. The results obtained showed that, under the cooking conditions applied, either including the use of a catalyst or not, delignification increased by increasing the cooking time, although the brightness of the handsheets was reduced. These results involved a secondary reaction between the organic solvent glycerol and the micro-fragments of fibers during cooking.
    [Show full text]
  • Black Liquor Recovery Boiler Advisory Committee
    BLACK LIQUOR RECOVERY BOILER ADVISORY COMMITTEE MINUTES OF MEETING Crowne Plaza Hotel/Atlanta Airport October 24, 25 & 26, 2016 OBJECTIVE BLRBAC’s objective is to promote improved safety of chemical recovery boilers and their auxiliaries through the interchange of technical knowledge, experience, and data on past and any future recovery boiler incidents. Bylaws - 2.1 OFFICERS Chairman: John Gray Tel: 912-277-1388 Rayonier Advanced Materials Cell: 912-321-7582 10 Gum Street [email protected] Fernandina Beach, FL 32035 Vice- Dave Slagel Tel: 912-966-4312 Chairman: International Paper Cell: 912-247-6295 1 Bonnybridge Road [email protected] Port Wentworth, GA 31407 Secretary: Everett Hume Tel: 781-255-4733 FM Global Cell: 413-323-6781 1151 Boston-Providence Turnpike [email protected] Norwood, MA 02062 Treasurer: Len Olavessen Cell: 901 573 8343 LENRO, Inc. [email protected] 1851 N. Virginia Avenue Bartow, FL 33830 REGULAR MEMBERSHIP Organizations operating, manufacturing, or insuring chemical recovery boilers are eligible. ASSOCIATE MEMBERSHIP Organizations having a direct interest or role in the safety of chemical recovery boilers are eligible. CORRESPONDING MEMBERSHIP A company residing outside of the United States which finds it impractical to attend meetings on a regular basis because of distance and expenses, but desires to be involved and informed of BLRBAC activities. Bylaws - 3.1 BLRBAC INTERNET ADDRESS: ---- www.blrbac.org IRS Employer ID/Tax ID (IRS E.I.N.T./T.I.N) ---- #13-366-5137 Meeting Minutes BLRBAC October 7, 2015 EXECUTIVE COMMITTEE John Gray Dave Slagel BLRBAC Chairman BLRBAC Vice-Chairman Rayonier Advanced Materials International Paper 10 Gum Street 1 Bonnybridge Road Fernandina Beach, FL 32035 Port Wentworth, GA 31407 Tel: 904-277-1388 Tel: 912-9664312 Cell: 912-321-7582 Cell: 912-247-6295 [email protected] [email protected] Everett Hume Len Olavessen BLRBAC Secretary BLRBAC Treasurer FM Global LENRO, Inc.
    [Show full text]
  • Techno Economic Evaluation of Lignin Extraction in a Dissolving Pulp Biorefinery
    NWBC 2017, Stockholm, March 28-30 Techno economic evaluation of lignin extraction in a dissolving pulp biorefinery Lindgren Karin, Samuelsson Åsa, Kulander Ida RISE, Bioeconomy, Stockholm, Sweden Abstract Material and energy balances of a modern theoretical dissolving softwood kraft pulp mill, using pre-hydrolysis in water, have been established. The mill produces 1000 ADt/day and there is an energy excess in the mill that could be used to produce power. If lignin is removed with the LignoBoost process the recovery boiler is unloaded enabling an increased pulp production. With a lignin removal of 0.2 ton/ADt the pulp production could increase 8.5%. According to a sensitivity analysis the lignin price has the largest impact on the economic performance. Introduction Full mill simulation models for market kraft pulp production have been developed in different projects for European softwood, birch and eucalyptus [1]. The models have been used during a number of years both in research activities and in mill specific projects for trouble shooting and as a basis for evaluation of new process concepts. Recently, many mills have shown an interest in upgrading their process to production of dissolving pulp, which traditionally has a higher market price than the market pulp. To meet this trend a simulation model for dissolving pulp production using pre-hydrolysis kraft process was developed at Innventia. Material and energy balances have been established using the simulation program WinGEMS 5.0 and all data presented are for steady state operation. The model has been used to evaluate effects of a lignin removal combined with an increased pulp production.
    [Show full text]
  • The Next Generation Lignoboost – Tailor-Maid Lignin Production for Different Lignin Bioproduct Markets
    Published May 26, 2017 Next Generation LignoBoost The next generation LignoBoost – tailor-maid lignin production for different lignin bioproduct markets Executive Summary The list of end products that can be made from lignin ranges from fuel applications to carbon fibers and fine chemicals. As more lignin becomes available on the market one key question that needs to be addressed is, of course; What to do with the produced lignin? This paper describes highlights and important results from collaborations aimed to develop add-on processes that will produce lignin with a tailored specification. Pilot scale trials have been carried out producing a bio based carbon black from lignin. Carbon black can be used as reinforcement filler in rubber products. It was also shown that an odor free lignin could be produced by decreasing the guaiacol content in the lignin from 1.42 mg/kg to 0.04 mg/kg. The odor free lignin concept is ready for commercialization enabling production of a completely odor free bio- composite from lignin. © Valmet Page | 1 Published May 26, 2017 Next Generation LignoBoost Introduction Kraft lignin production at large scale is commercial and purified lignin is sold globally. Known trade names for lignin are BioChoice™ (Domtar) and BioPiva™ (UPM). Several pulp and paper manufacturers, such as Stora Enso, Domtar, UPM, Metsä Fibre, Suzano and Fibria, are changing their image to a broader bioproduct scope, including a production of lignin. When producing pulp according to the traditional kraft method the overall yield going from wood to pulp is about 50%. Part of the other 50% is used to produce new cooking chemicals, electricity and heat.
    [Show full text]
  • Increasing Electricity Generating Potential from Pulp Mills
    Recovery boiler history and future Esa K. Vakkilainen, Lappeenranta University of Technology, P.O. Box. 20, FI-53581 Lappeenranta, Finland INTRODUCTION Recovery boilers are built all over the world. The roots of recovery technology are longer than the roots of recovery boilers. But it wasn’t until the invention of recovery boilers before the Second World War that the pulping technology was revolutionalized. This led to long development of essentially the same type of equipment, culminating into units that are largest biofuel boilers in the world. Early recovery technology concentrated on chemical recovery as chemicals cost money and if one could recycle these chemicals then the profitability of pulp manufacture would improve. For pulp mills the significance of electricity generation from the recovery boiler was for long secondary. The most important design criterion for the recovery boiler was a high availability. The electricity generation in recovery boiler process can be increased by elevated main steam pressure and temperature or by higher black liquor dry solids as well as improving its steam cycle. This has been done in the modern Scandinavian units. EARLY RECOVERY TECHNOLOGY Early recovery technology concentrated on chemical recovery (Deeley and Kirkby, 1967). Chemicals cost money and it was easy to discover that recycling these chemicals would improve the profitability of pulp manufacture (Vakkilainen, 2005). Recovery of pulping chemicals could be based to French chemist Nicholas LeBlanc’s process for producing soda at reducing furnace. A flame oven was hand filled with black liquor, Figure 1. Then the black liquor was dried with flue gases from burning wood.
    [Show full text]