Indian Institute of Technology Delhi Hauz Khas, New Delhi India-110016 http://www.iitd.ac.in Trident Complex, Raikot Road, Barnala, Punjab, India-148101 Tel: +91-161-5039999, Fax: +91-161-5038800 http://www.tridentindia.com CHC410 Internship Project Report Submitted by Lavanya Kumar Jain 2007CH10069, Student Chemical Engineering Department, IIT Delhi, New Delhi, India Phone: +91 9953181003; Email:
[email protected] Faculty Supervisor Anurag S. Rathore Associate Professor Chemical Engineering Department, IIT Delhi, New Delhi, India Phone: +91-9650770650; Email:
[email protected] INTERNSHIP SUMMARY Name of the Company: Internship period: No. of days: Location: Department: Unit: Project Supervisor: Abhishek Industries Ltd (Trident Group) 17th May – 16th July 2010 52 Dhaula complex, Barnala, Punjab Production Paper (PPR) Mr. Sumit Jindal, FLE, Recovery 2, PPR Abhishek Industries Limited Phone: +91 9878997774; Email:
[email protected] Reduction of chemical losses in Recovery Project Title: ABSTRACT The project at Abhishek Industries is concerned to analysing ORE and identifying sources of soda loss in the whole process and suggesting measures to reduce soda loss. The streams carrying alkali are studied and all the possible exit points for alkali are identified. The major sources of loss are individually studied and various measures are suggested to increase their performance and reduce soda loss. Experiments are conducted at several occasions to analyze the affects of suggested measure. The method of ORE calculation is also corrected and automation is suggested at several points for better control of process. ORE is calculated based on individual losses from soda loss sources. Summary of the Report: 1. IDENTIFICATION OF ALKALI EXIT POINTS: Recovery 2 plant and Pulp mill are rigorously analyzed and all the possible exit points of alkali from the system are identified. Process flow diagram for each unit is provided. FMEA ON ALKALI EXIT POINTS: Results are derived from FMEA and a final list of prominent alkali loss points is made based on Perito hypothesis. WBL SAMPLING TO STUDY VARIATION IN COMPOSITION: WBL samples are analysed at frequent intervals to study variation in actual WBL composition to value used for ORE calculation. Error in SRE and ORE values due to above variation is calculated. COMPOSITE SAMPLING AND AUTOMATION: Collection tank design for composite sampling is proposed. Advantages of Automation and suppliers of online analyzers are provided. MUD FILTER ORE LOSS: ORE loss from mud filter is calculated from lime consumption and % composition data of mud cake. Loss from Grifts and stones is also calculated. 2. 3. 4. 5. 2|P a ge 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. MUD FILTER PROCESS PARAMETER ANALYSIS: Process parameters that affect performance of mud filter are identified and analyzed. Experiments are done to test vat solid composition, homogeneity in vat mixture. Impact of displacement washing on alkali content in mud cake is discussed. CAUSTICIZING CONTROL MODELS: 3 causticizing control models, including Advanced control are discussed to maintain consistent causticizing efficiency and avoid excess lime addition. PULP MILL SODA CARRYOVER ORE LOSS: From production data and Soda as kg/MT TTA as Na2O, total soda loss and loss in ORE is calculated. PULP MILL PRODUCTION VERSUS SODA CARRYOVER LOSSES: Soda carryover with production for SFL and WFL are plotted and the trend is analysed. WASHER EFFICIENCY FOR SFL AND WFL: Project in SFL and WFL to reduce soda loss are discussed. TOTAL WASHABLE ALKALI AS SODA CARRYOVER IN WFL: Elemental analysis of filtrate of thoroughly washed pulp is done to calculate total washable alkali of total alkali as soda carryover in WFL. PULP MILL REJECT ORE LOSSES: Total soda loss and total washable soda loss calculations are done for reject streams in SFL and WFL. ORE loss through reject stream is calculated using these data. REJECT STREAM WASHING SOLUTIONS: Reject streams in SFL and WFL are thoroughly studied with sufficient flow diagrams. Solutions are suggested to reduce soda loss through reject. ESP PROCESS PARAMETER ANALYSIS: Various process parameters are identified and analysed that affect the performance of ESP. COLLECTION EFFICIENCY CALCULATION: Ash collection rate from ESP is calculated from AMT density sampling at specific intervals of time. Inlet gas flowrates are noted during the sampling period. With other parameters constant collection efficiency is calculated for the ESP. DUST COMPOSTION: ESP dust composition and Chlorine Enrichment Factor (CEF) and Potassium Enrichment Factor (PEF) are calculated. POTASSIUM AND CHLORIDE PURGING: The problem of high content of chlorides and potassium in the system is discussed. Methods for their removal and systems based on Ash Leaching are provided. ORE LOSS DATA: Tentative % Loss in ORE from all the loss points is presented. ORE based on individual losses is calculated. 3|P a ge INDEX Contents Internship Summary Abstract Abhishek Industries 1. 1.1. 1.2. 1.3. 1.4. 2. 3. 4. 4.1. 4.2. 4.3. 4.4. 5. 5.1. 5.2. 5.3. 5.4. 6. 6.1. 6.2. 6.3. 6.4. 7. 7.1. 7.2. 7.3. 8. 8.1. 8.2. 9. 9.1. 9.2. 9.3. 9.4. 9.5. 9.6. 10. Introduction Paper making process Paper plant at Abhishek Industries Recovery units ORE Objective Project Plan Alkali Exit Points Recovery 2 SFL WFL Significant permanent loss points WBL Sampling ORE fluctuations WBL sampling Composite sampling Automation Mud Filter Lime Mud ClariDisc system Mud Filter ORE loss Process parameter testing Causticizing control models Pulp mill soda carryover Pulp mill soda carryover ORE loss Pulp mill production versus soda carryover losses Washer efficiency for SFL and WFL Pulp mill Reject Pulp mill Reject ORE losses Reject stream washing ESP BHEL ESP system Process parameters Collection Efficiency Dust Composition Potassium and Chloride Purging ESP ORE Loss ORE Loss data Page Number 2 2 6 11 11 11 12 16 17 17 18 17 24 26 26 30 30 32 36 38 39 39 40 41 48 49 49 50 54 56 56 59 63 64 65 70 74 75 77 78 4|P a ge 11. 12. Future Work References 79 80 81 81 82 84 List of Experiments List of Tables List of Figures Appendix A (Data Tables) 5|P a ge ABHISHEK INDUSTRIES Trident Group commenced its operations in 1985 with Single Super Phosphate (capacity 66000 tonnes per annum) & Sulphuric Acid (capacity 33000 tonnes per annum). Since then, the business of the group witnessed a wide range of diversification and expansions and today, Trident Group is a Rs. 25 billion global conglomerate with an employee headcount of more than 10,000, and providing indirect employment to 20,000 people. Therefore, Trident is a pioneer at implementing sound Corporate Governance as the basic management principle. Abhishek Industries Limited (AIL) is the flagship company of the Trident Group and deals in Yarns, Towels, Papers, and Chemicals & Energy. The company is among the top 5 global terry towel giants of the world. It is one of the world's largest agro-based paper manufacturers and one of the largest yarn producers in India. Abhishek Industries has 3 plants located at Dhaula (Punjab), Sangheda (Punjab) and Budhni (Madhya Pradesh). At present the company is having following manufacturing facilities: • Yarns 12592 spindles • Yarn Processing 6825 tonnes/ day • Open end Yarn 1920 rotors • Terry Towels 268 looms • Writing & Printing Papers 400 tonnes/ day • Sulfuric Acid 100000 tonnes/ annum In brief, Leadership: Ownership: Total Assets: CAGR: Employees: Exports: Mr. Rajinder Gupta, CEO and MD Public limited company with Public shareholding 36.52 %, and Foreign shareholding 6.32 %. Rs. 25 billion 30% Over 10,00 (Indirect employment to 20000 people) 47% of Net Sales across 65 countries Financial Performance, (Rs. millions) PERIOD ENDED NO. OF MONTHS GROSS TURNOVER NET SALES EXPORTS GROSS PROFIT (PBIDT) NET PROFIT AFTER TAX NET WORTH FIXED ASSETS (GROSS BLOCK) CURRENT ASSETS (NET) MAR 2009 12 15456 13981 6862 2605 (530) 4463 21032 2365 MAR 2010 12 19768 18034 8392 3560 565 5028 23388 5285 6|P a ge MUSKAAN, SHAAN, SGA Several employee engagement initiatives including Total Quality Assurance (TQA), Kaizen (MUSKAAN), SHAAN, Small Group Activity (SGA) etc have been taken up for creating a quality driven culture through the involvement of ground level employees. These initiatives focused on building awareness and developing skills in Kaizen, 5 S, etc. MUSKAAN MUSKAAN is company’s own nomenclature for KAIZEN. This initiative has been undertaken so as to ensure that members in the Organization undertake small improvements of permanent nature in their own work area and department. The focus of the initiative is to help reduce strain and extra effort, improve quality and reduce inconsistencies and any wasteful activity. The Organization is now moving towards Phase II and the focus is towards facilitating innovation, creativity and process improvements. SHAAN Like Muskaan, SHAAN is company’s own nomenclature for 5 S. The program has been initiated to harness the benefits of increased efficiency due to reduced time in looking for tools and equipment, improved quality, work standardization, reduced changeover time, and improved safety, reduced space requirements & storage costs, reduced machine down time and simplified work environment, etc. Regular trainings are being imparted to our members on the same. SGA Small Group Activities have been undertaken by members for improving the process capability in all the production and support processes and to make the processes more efficient. ABHISHEK YARN, TEXTILES, PAPER, SAP, COGEN, UTILITY ABHISHEK YARNS The Yarn Division of the company manufactures both Combed and Carded yarn in addition to polyester cotton and PVA yarn. Besides catering to the captive consumption by Home Textiles Division, the Yarn Division has developed a significant presence in the export market with its quality products. Currently, AIL has 125,952 spindles operating at almost 100% capacity producing value added yarns such as yarn made from Egyptian cotton, PVA fiber and Bamboo fiber. Also, AIL has upgraded its existing spinning facilities through automation and increasing the value adding processes. Abhishek Yarns supplies the processed yarns to the following mills: Arvind Mills; Elegant Overseas; Kapoor Industries; Abhitex Industry; Chemitax, Belgium; SPL Industries; Aashima Industries and Alok Industries. ABHISHEK TEXTILES The Home Textiles Business of the company is the prime source of Export Earnings and International Recognition to the company. AIL supplies its Toweling products to world’s biggest and most reputed companies and retail chain stores like Wal*Mart, Luxury Linens, JC Penney, Target, BBB, Chris 7|P a ge Madden, TJ Maxx, Franco and Sears. Among the top 20 retailers of the world, AIL has business relationship with at least 11 of them. The company has a significant presence in the mid and high segment of the Terry Towel market, with an impressive product profile. Currently, the division operates with an installed capacity of 268 looms of towels and 6825 TPA of processed yarn. Ultramodern German, Swiss and Italian technology has been adopted in order to provide consumers the products that they cherish. ABHISHEK PAPER The Paper Division of Trident was commissioned in 1992 and presently the production capacity is 400 TPD. The focus is on manufacturing Writing and Printing grades of paper for different segments. The unit specializes in using Wheat Straw, an Agro residue as its prime raw material, thus facilitating an eco-friendly environment and maintaining the ecology of the place. Applications: a. Calendar & Diary Printing b. Business & Computer Stationery c. Multicolor High End Printing & Publishing d. Base paper for coated papers e. Novels publication f. High Speed Photocopying g. Laser & Inkjet Printing h. Multipurpose Office Use Paper At Abhishek Industries there are two pulp units, Pulp 1 for producing pulp from wood i.e. wood fiber line (WFL) and Pulp 2 for producing pulp using wheat straw i.e. straw fiber line(SFL). The SFL unit is the biggest pulp producing unit in the world that utilizes wheat straw as a raw material. SAP (SULFURIC ACID PLANT) Sulfuric acid is produced from sulfur, oxygen and water via the conventional contact process (DCDA) In the first step, sulfur is burned to produce sulfur dioxide. S (s) + O2 (g) → SO2 (g) This is then oxidized to sulfur trioxide using oxygen in the presence of a vanadium (V) oxide catalyst. 2 SO2 (g) + O2 (g) → 2 SO3 (g) (in presence of V2O5) The sulfur trioxide is absorbed into 97-98% H2SO4 to form oleum (H2S2O7), also known as fuming sulfuric acid. The oleum is then diluted with water to form concentrated sulfuric acid. H2SO4 (l) + SO3 → H2S2O7 (l) H2S2O7 (l) + H2O (l) → 2 H2SO4 (l) 8|P a ge The production of SAP is 100000 tonnes/ annum Figure 1. Sulfuric Acid Plant (SAP) at Abhishek Industries, Dhaula complex COGEN The units of Abhisehk Industries meet their own energy demands. There are 5 COGEN units with 2 large units of 20 MW each and 3 units of combined capacity of 9.34 MW. The total power generation capacity is 49.34 MW. The requirement is 40 MW. Steam is the main product of these units and is converted to different temperature and pressure conditions depending on requirements. Figure 2. COGEN-1, a 20 MW unit at Abhishek Industries, Dhaula complex 9|P a ge UTILITY There is waste water treatment plant and effluent treatment plant in the Dhaula industrial campus. It reduces BOD and COD of streams and protects environment. Also, a demineralised water plant supplies demineralised water to all the units. Figure 3. Demineralised water plant at Abhishek Industries at Dhaula complex In brief, BUSINESS UNIT Abhishek Home Textiles (AHT) 1998 Abhishek Yarn 1992 Abhishek Paper 2002 Abhishek Chemicals 1985 COGEN Power CAPACITY 374 looms 224,448 spindles and 1,920 rotors 175,000 tpa 1,00,000 tpa 50 MW PRODUCTION (2010) 29,152 tonnes 48,115 tonnes 123,629 tonnes 4,951.8 84,038 tonnes 328,534 Mwh units REVENUE (Rs. millions) 8,482.5 6,187.0 10 | P a g e 1. 1.1. INTRODUCTION PAPER MAKING PROCESS Paper making process involves pulping of the raw material. Pulping can be carried out through chemical pulping or mechanical pulping. For chemical pulping there could be various processes, viz. Kraft process, sulphite process and soda pulping. Sulfite pulping is carried out between pH 1.5 and 5, depending on the counterion to sulfite (bisulfite) and the ratio of base to sulfurous acid. The pulp is in contact with the pulping chemicals for 4 to 14 hours and at temperatures ranging from 130 to 160 °C.1 In the Soda-AQ process, anthraquinone (AQ) may be used as a pulping additive to decrease the carbohydrate degradation. The soda process gives pulp with lower tear strength than other chemical pulping processes.2 Kraft process is the most common applied process and entails treatment of raw fiber with a mixture of sodium hydroxide and sodium sulfide, known as white liquor, that break the bonds that link lignin to the cellulose. Cooking produces black liquor that contains lignin fragments, carbohydrates from the breakdown of hemicellulose, sodium carbonate, sodium sulfate and other inorganic salts. A Recovery plant process black liquor and produces White liquor to be reused in the digester for cooking. Figure 1.1. Paper making process 1.2. PAPER PLANT AT ABHISHEK INDUSTRIES The paper plant at Abhishek Industries is based on Kraft Process. The capacity of paper plant is 400 MT/day. However, current production is 420 MT/day. The raw material used for making paper is a mixture of wheat straw and wood chips in ratio of approximately 70:30. By using the wheat straw as 1 2 http://en.wikipedia.org/wiki/Sulfite_process http://en.wikipedia.org/wiki/Soda_pulping 11 | P a g e raw material, Abhishek industries has saved thousands of trees for being used to make paper, but using wheat straw has its own disadvantages in purity and paper quality. It also faces problem of limited research on plant processes. A paper plant basically consists of a Pulp Mill, Paper Machine and Finishing section and utility as Recovery. At Abhishek Industries there are 2 pulp mills, SFL and WFL. Straw Fiber Line (SFL) processes wheat straw and produces pulp, with present production around 230 tonnes of bleached pulp per day. Wood Fiber Line (WFL) processes wood chips and produces pulp, with present production around 100 tonnes of bleached pulp per day. There are 2 paper machines, Paper Machine 1 and Paper Machine 2. There are 2 Recovery Units, Recovery 1 and Recovery 2. Figure 1.2. Paper making flowchart3 1.3. RECOVERY UNITS The first step of chemical recovery is the evaporation process, which increases the concentration of solids from approximately 15 percent to more than 60 percent. The concentrated slurry contains approximately 50 percent organic solids and 6 percent total sulfur in the form of sodium sulfate 3 Mckean W. and Jacobs R. S. (1997) Wheat Straw as a Paper Fiber Source 12 | P a g e (Na2SO4) and sodium thiosulfate (Na2S2O3) and is placed into a recovery boiler. The organic solids are burned for energy while the inorganic process chemicals, also known as smelt, flow through the floor of the recovery boiler to be recausticized.4 Raw Material [Wheat Straw/ Wood Chips] White Liquor Quick Lime Pulping Weak Black Liquor (WBL) [10-12 % Solids] To Energy Lime Kiln Causticizer Steam Evaporator Lime Mud Green Liquor Limestone Makeup Figure 1.3. Chemical Recovery Cycle Combustion [Recovery Boiler] Heavy Black Liquor (HBL) At Abhishek Industries, Recovery 1 has a capacity of around 130 tonnes of dry solids fired per day and Recovery 2 has a capacity of 400 tonnes of dry solids fired per day. 1.3.1. MULTIPLE EFFECT EVAPORATORS Figure 1.4. Multiple effect evaporators 4 M. Brongers, A. J. Mierzwa. Pulp and Paper 13 | P a g e The first step in recovering the chemicals from the black liquor is evaporation. This removes excess water from the black liquor and maximizes the fuel value for the recovery furnace. 1.3.2. RECOVERY BOILER Figure 1.5. Recovery Boiler Process flow Figure 1.6. Recovery Boiler 14 | P a g e A recovery boiler consists of heat transfer surfaces made of steel tube; furnace-1, superheaters-2, boiler generating bank-3 and economizers-4. The steam drum-5 design is of single-drum type. The air and black liquor are introduced through primary and secondary air ports-6, liquor guns-7 and tertiary air ports-8. The combustion residue, smelt exits through smelt spouts-9 to the dissolving tank-10. 1.3.3. RECAUSTICIZING PLANT Figure 1.7. Recausticizing Process flow Recausticizing is the process used to transform the inorganic smelt recovered from the recovery boiler into white liquor so that the chemicals may be recycled. The recycled inorganic chemicals are discharged as molten smelt from the recovery boiler and then dissolved using water to form green liquor. Any unwanted substances are precipitated out. Lime is then added to the clarified green liquor to produce sodium hydroxide (NaOH) from the remaining sodium carbonate (Na2CO3). The resulting solution (white liquor) contains sodium hydroxide, sodium sulfide (Na2S), and a solid phase of calcium carbonate (lime mud). Before the white liquor is recycled back to the digester, the white liquor is clarified further to remove the lime mud.5 The main necessities for Soda Recovery Plant are: a. Maintaining required Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) levels as per Environmental regulations. COD of inlet liquor to recovery plant is in lakhs, while regulations are 300 for COD and 30 for BOD. b. Recovery of caustic soda (NaOH) that results in cost benefits. c. Energy production as steam by burning organic material in black liquor, lignin. 5 M. Brongers, A. J. Mierzwa. Pulp and Paper 15 | P a g e 1.4. OVERALL RECOVERY EFFICIENCY As the purpose of a Soda Recovery unit is to recover caustic soda from Black liquor, it calculates the total efficiency of caustic soda recovered through a generalized term as Overall Recovery Efficiency (ORE) which incorporates caustic soda losses both at pulp mills and in recovery units. ORE = SRE X PME Soda Recover Efficiency, SRE = (WL supply to Pulp mill) ± (Recovery stock difference) WBL Received Pulp Mill Efficiency, PME = (WBL received by recovery) ± (WBL stock difference of Pulp mill) (WL supply to Pulp mill) + (Purchased caustic) ± (WL stock difference of PM) 1.4.1. ORE CALCULATIONS Basis: TTA as Na2O A B C D E F G J P Q R WL used in cooking in SFL and WFL OS of WBL+WL in SFL and WFL OS of WBL+SCBL+GL+WWL+WL in Rec-1 OS of WBL+HBL+GL+WWL+WL in Rec-2 CS of WBL+WL in SFL and WFL CS of WBL+SCBL+GL+WWL+WL in Rec-1 CS of WBL+HBL+GL+WWL+WL in Rec-2 Purchased caustic used in cooking in SFL and WFL = = = B+C+D E+F+G A + [J x 31/40] Glossary: Total Titrable Alkali (TTA): Na2CO3, NaOH, Na2S Total Active Alkali (TAA): NaOH, Na2S OS: Opening Stock CS: Closing Stock WL: White Liquor WBL: Weak Black Liquor SCBL: Semi-Conc. Black Liquor Loss % = ORE % = ∗ ∗ 100 HBL: Heavy Black Liquor GL: Green Liquor WWL: Weak White Liquor 100 – Loss % The present ORE varies between 94-95 % on a general basis for the paper plant at Abhishek Industries. 16 | P a g e 2. OBJECTIVE The objective of the project is to identify the potential sources of soda loss in the whole stream including both pulp mill and recovery units and present some solutions for further increment in ORE. 3. PROJECT PLAN 17.05.10 25.05.10 26.05.10 03.06.10 04.06.10 15.06.10 16.06.10 24.06.10 25.06.10 01.07.10 02.07.10 08.07.10 09.07.10 12.07.10 • Induction programme • WBL Sampling • Mud Filter • Pulp mill soda carryover • Pulp mill Reject • ESP • ORE Loss data 17 | P a g e 4. 4.1. ALKALI EXIT POINTS RECOVERY 2 WBL from pulp mill Pulp Mill WBL Storage Tank Rotary Lime Kiln Evaporator, 7 effects and 11 bodies [10% to 65%, 170T/hr] Lime Mud Steam, 460 °C, 64 kg/cm2 WL Storage Tank Causticizing [110 MT/day] HBL Storage Tank [65-67% solids] Recovery Boiler [Total heat transfer area = 7283 m2] Smelt Dissolving tank, Green liquor [97-102 GPL Na2O TTA] Figure 4.1. Process Flow Diagram of Recovery 2 4.1.1. EVAPORATOR Before WBL is sent to evaporation it is filtered to remove fibers (cellulose) that has come along it. It is necessary to remove it else it will scale the evaporator. These fibers are recycled and some amount is thrown away with some amount of Black liquor. Before feeding into evaporator WL is added to WBL to reduce the viscosity and fraction. LP steam is preferred in evaporators. First it’s difficult to deal with very high pressures. More importantly latent heat, λ of steam decreases with increasing temperature or high pressure. It is advisable to feed the steam at saturation temperature as retention time of steam in evaporator is less and latent heat transfer is more effective. Effects 1(A, B, C) and 2(A, B, C) have high pressure, while rest work in vacuum. Inlet temperature and pressure of steam is 140 °C, 2.5 kg/cm2. Pressure in the last effect is 0.14 kg/cm2. It is feed backward system of evaporator. The concentration in outlet of 3rd effect is 25% solids. Concentration in inlet of 7th effect was 10% solids. In 2nd effect concentration rises to 36% solids. In 1st effect it rises to 6567% solids. As there is significant change in concentration in first 2 effects there is considerable rise in viscosity. Thus, first 2 effects are divided into 3 separate bodies. Same steam is fed in 3 bodies of an effect, while flow of Black liquor is continuous and simultaneous. First body is called wash, second as intermediate and third as product. Vapors from each effect sent to condenser. It contains same amount of soda. 18 | P a g e Black liquor [11-12% solids] Vibratory Screens [5 Nos] Fibres BL Pit WBL Storage Tank [3 Nos] WWL (to reduce viscosity) LP Steam Thrown Out Evaporator [7 effects] Boiler HBL Storage Tank [65-67% solids] BL Pit Washing Figure 4.2. Evaporator Process Flow Diagram Vapor to condenser [40 ppm] The identified exit points of soda for permanent losses are: a. b. c. d. e. Vibratory Screens reject Vapors to Condensers Washing/Scaling Tank overflows Seepages and Pump leakages Figure 4.3. 7 effect-11 body Evaporator at Recovery 2 at Abhishek Industries, Dhaula complex 19 | P a g e Figure 4.4. Condensers at Recovery 2 at Abhishek Industries, Dhaula complex 4.1.2. RECOVERY BOILER The Recovery boiler has 3 main parts: a. Black liquor burning and Green liquor collection b. Flue gas flow and heat transfer c. Demineralised and deaerated water flow and heat transfer 4.1.2.1. Black liquor firing HBL from storage tank is preheated to reach a desired temperature of 120 °C in an indirect heater. If indirect heater is not able to heat it, direct heater is used. The liquor stream distributes into 6 nozzles. With pressurized steam, BL is sprayed in furnace from these 6 nozzles. Initially fuel oil is used by its own component, lignin. Green liquor falls at the bottom and is collected in Main Dissolving Tank (MDT). It is highly concentrated and very hot at temperature of around 1000 °C. Precautions are taken in dissolving GL. As it’s very hot direct addition of water will convert it into steam and explode. Thus, hot water/steam jets hit the fine stream of GL falling and dilute it. Instead of using hot water, WWL from Mud Washer 1 is used to dilute to GL that helps to maintain desired concentration. 20 | P a g e MDT has outlet for vapors. The soda carryover is very limited as WWL is sprinkled at 2 points in exiting vapors that settles solid particles in the stream. 4.1.2.2. Flue gas flow Air is pumped in furnace at 3 levels, viz. Primary, Secondary and Tertiary. ID fan sucks the air from furnace and pushes it through chimney. Flue gas generated on burning lignin travels through superheaters, boiler bank and then economizer. It passes through ESP and exits from chimney top. 4.1.2.3. Water and steam system Demineralised water is pumped in deaeration tank. The water is then pumped in economizer, then to boiler bank and then to superheaters to produce to produce high pressure superheated steam, which is sent to power boiler. The water from deaeration tank is passed through economizer and not through superheaters as flue gas has enough heat to provide latent heat to water, which if otherwise had been passed through superheaters would have extracted heat from high temperature flu gas. Thus, final temperature of the steam would be less and exit temperature of the flue gas would be high. Steam HBL Storage Tank [65-67% solids] Indirect heater 120 °C Direct heater 3 air pumps (Pri-Sec-Ter) Flue Gas Stem Drum Hot Water Boiler Bank Steam Economiser – 1, 2 Pri - Sec -Ter Superheaters Furnace [6 firing guns] Fuel Oil De-aeration Tank DM water ESP Power Boiler [HP steam, 460 °C, 63 bars] Main dissolving tank WWL MDT Outlet GL Storage Tank Chimney Soot Blower WWL Ash Mixing Tank Figure 4.5. Recovery Boiler Process Flow Diagram 21 | P a g e The identified exit points of soda for permanent losses are: a. b. c. d. e. f. Flue gas carryover [ESP] MDT Outlet Dregs washer [Recovery 1] Washing/Scaling Tank overflows Seepages and pump leakages 4.1.3. RECAUSTICIZING PLANT Raw material to this unit is Green Liquor. The GL feed contains sodium carbonate in large proportion and some amount of sodium hydroxide and sulfide. The basic reaction that occurs in a Lime slaker is: Ca(OH)2 + Na2CO3 ↔ 2 NaOH + CaCO3 85% of equilibrium concentration is achieved in slakers. The rest is achieved in causticizers that provide retention time for completion of reaction. Rakes installed in clarifier and mud washers are bottleneck in the process. To prevent rake failure automatic rake lifting mechanism is put where rakes lift automatically on reaching certain limit loads. Rakes do not disturb the settling of suspended limestone and silica particles in clarifier and mud washer as it rotates at speed of 7 rev/min. Its purpose is to prevent deposition at the bottom and maintain continuous flow underflow concentrated with solids. The vacuum based rotating disk mud filters remove calcium carbonate as mud cake. It is fed to lime kiln to produce lime. Lime kiln is not functional at present as cost of furnace oil fed to lime kiln is higher than purchased lime. Lime kiln is 76m long and 4m wide huge rotary kiln. Figure 4.6. Rotary lime kiln 22 | P a g e Lime (Lime bin) GL Storage Tank [32-34% TTA as Na2O] Agitator GL Heater Slaker Rake Classifier Recovery Boiler Rake White liquor clarifier Steam Agitator Grits [Stones & Silica] Causticizer (4) [100°C, each gives retention time of 27-30 min] Overflow WL Storage Tank [95 GPL TTA as Na2O] Steam Underflow Rake Overflow Lime Mud [25 GPL as TTA as Na2O] Washer 1 Hot Water Weak White Liquor Storage Tank [25 GPL as TTA as Na2O] Overflow Underflow To Pulp Mill LMW 2 MDT Rake [5 GPL as TTA as Na2O] Hot Water Underflow Lime Mud Storage Tank Hot Water Overflow Mud Filter (Vacuum disk filters) [Pr = 550mmHg] Thrown Out Limestone Lime Kiln Furnace Oil Figure 4.7. Recausticizing Process Flow Diagram The identified exit points of soda for permanent losses are: a. b. c. d. e. Sludge/Mud cake carryover Grits and stones carryover Washing/Scaling Tank overflows Seepages and leakages Sludge Cake Lime to Lime bin 23 | P a g e 4.2. STRAW FIBER LINE (SFL) Figure 4.8. Wet Washing in SFL Figure 4.9. Digester in SFL 24 | P a g e Figure 4.10. Pulp washing in SFL Brownstock washing is a counterflow washing system with pulp and liquor stream flowing in opposite direction. The nomenclature of washer is based on pulp flow. The amount of water used for pulp washing is constrained at both lower and upper ends: a. For Recovery, more water for washing implies more load on evaporator and thus higher steam consumption. Thus, Recovery would like to reduce water content. b. For pulp mill, more water for washing implies better washing or more soda recovery. Thus, pulp mill would prefer high water usage. Soda carryover in pulp has 2 major disadvantages for pulp mill: a. Reduced paper quality, i.e. Brightness. b. Increased use of chemicals in bleaching and further processes in paper making. The identified exit points of soda for permanent losses are: a. Soda carryover with pulp b. Reject from HD cleaner c. Reject from Delta Knotter through Vibratory Screen 1 d. Reject from Delta Screen through Vibratory Screen 2 e. Reject from Centricleaner 25 | P a g e f. g. h. i. Carryover with Blow Tank vapors Washing/Scaling Tank overflows Seepages and Leakages Figure 4.11. Digester Feed Belt in SFL at Abhishek Industries, Dhuala complex 4.3. WOOD FIBER LINE (WFL) The process stream for WFL is almost similar with slight modifications. WFL has 3 Batch digesters as compared to continuous digesters in SFL. There are 5 simultaneous washers and no press. The different in the reject streams is discussed in details later. The identified exit points of soda for permanent losses are: a. b. c. d. e. f. g. Soda carryover with pulp Reject from Vibratory Screen Reject from Pressure Screen through centricleaner and vibratory screen Carryover with Blow Tank vapors Washing/Scaling Tank overflows Seepages and Leakages 4.4. SIGNIFICANT PERMANENT LOSS POINTS On discussion with experts, as well as workers employed in the company and on the basis of general information derived from case studies of paper plants around the globe, significant permanent loss points are identified as follows: a. b. c. d. e. f. Mud cake carryover Flue gas carryover Reject streams in Pulp mill Grifts and stones Soda carryover with pulp Carryover with Blow Tank vapors 26 | P a g e To confirm the identified loss points, FMEA (Failure Mode Effectiveness Analysis) statistical analysis was performed. Experiment: FMEA on identified exit points of soda for permanent losses Objective: To identify the significant permanent loss points Survey Format: FMEA on identified exit points of soda for permanent losses Cause No. C1 C2 C3 C4 Cause Severity Occurrence Detection RPN No. Soda carryover with pulp Mud cake carryover Reject streams in Pulp mills Flue gas carryover [ESP] Carryover with Blow Tank C5 vapors C6 MDT Outlet C7 Dregs washer [Recovery 1] C8 Grifts and stones C9 Seepages and Leakages at WFL Vibratory Screens reject in C10 Evaporator C11 Washing/Scaling at WFL Washing/Scaling in C12 Recausticizing C13 Vapors to Condensers C14 Washing/Scaling in Evaporator Seepages and Pump leakages C15 in Evaporator Seepages and Pump leakages C16 in SFL C17 Tank overflows in WFL C18 Tank overflows in Evaporator Washing/Scaling in Recovery C19 Boiler Tank overflows in Recovery C20 Boiler Seepages and Pump leakages C21 in Recovery Boiler Tank overflows in C22 Recausticizing Seepages and Pump leakages C23 in Reausticizing C24 Washing/Scaling at SFL C25 Tank overflows in SFL *Fill with 1, 3 or 9 27 | P a g e Observation table and Results: FMEA on identified exit points of soda for permanent losses P1 P2 P3 P4 P5 P6 P7 P8 P9 RPN No. 729 621 549 531 99 18.7906 18.1746 3.38848 21.255 24.9515 24.9515 46.2065 64.9971 83.1717 86.5602 89.5836 60.3333 2.06503 27 9 3 9 27 1 9 1 9 27 9 27 81 3 9 9 27 3 9 27 3 9 43.6667 1.49458 41 1.40331 33.6667 1.15231 3 25 0.85568 24.1111 0.82525 23.2222 0.79483 91.6486 93.1432 94.5465 95.6988 96.5545 97.3797 98.1746 28 | P a g e Cause No. 729 729 243 243 729 729 729 27 27 3 3 9 3 9 27 3 81 81 81 81 243 81 9 81 9 81 27 1 27 3 81 3 27 9 27 81 81 27 9 81 81 9 9 243 3 27 27 81 81 81 81 81 9 81 9 9 81 243 243 81 243 243 27 81 27 729 81 729 81 729 729 729 81 729 729 243 729 729 243 729 729 729 243 729 729 729 729 729 729 729 729 729 729 729 Cause Actual % Cumulative % C1 Soda carryover with pulp C2 Mud cake carryover C3 C4 C5 Reject streams in Pulp mills Flue gas carryover [ESP] Carryover with Blow Tank vapors 88.3333 3.02339 C6 MDT Outlet C7 Dregs washer [Recovery 1] C8 Grifts and stones C9 C10 C11 C12 Seepages and Leakages at WFL Vibratory Screens reject in Evaporator Washing/Scaling at WFL Washing/Scaling in Recausticizing C13 Vapors to Condensers C14 27 27 3 9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 9 1 1 1 3 1 1 1 2.11111 0.07226 0.03423 0.03423 0.03423 0.03423 0.03423 0.03423 3 1 9 1 1 9 1 3 3.22222 0.11029 1 9 3 3 9 3 3 1 4.55556 0.15592 99.6121 99.7224 99.7946 99.8289 99.8631 99.8973 99.9315 99.9658 100 100 9 3 1 27 3 9 9 3 7.44444 0.2548 99.4562 3 3 27 9 9 27 3 3 12.3333 0.42213 99.2014 27 9 27 27 9 27 3 3 17.6667 0.60468 98.7792 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 Washing/Scaling in Evaporator Seepages and Pump leakages in Evaporator Seepages and Pump leakages in SFL Tank overflows in WFL Tank overflows in Evaporator Washing/Scaling in Recovery Boiler Tank overflows in Recovery Boiler Seepages and Pump leakages in Recovery Boiler Tank overflows in Recausticizing Seepages and Pump leakages in Reausticizing Washing/Scaling at SFL C25 Tank overflows in SFL 29 | P a g e 800 700 600 500 400 300 200 100 0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223242526 120 100 80 60 40 20 0 Average RPN Np. Cumulative % Conclusion: The finally identified significant permanent loss points based on Perito hypothesis are as follows: a. b. c. d. Mud cake carryover Flue gas carryover [ESP] Reject streams in Pulp mill Soda carryover with pulp Experiment 4.1. FMEA on identified exit points of soda for permanent losses 5. 5.1. WBL SAMPLING ORE FLUCTUATIONS SRE and PME fluctuate between 80 to 120 on per day basis and thus, ORE fluctuates. With approximately steady process, the losses are also steady. Thus, fluctuations in SRE, PME and ORE values should be low. The reasons identified are: a. Measurement error of WBL GPL: There is high variability in WBL GPL values. Sampling followed is Grab sampling which doesn’t normalize these variations. b. Increase or decrease in processed liquor: When more liquor is processed losses associated with processing are higher, thus ORE decreases. Increase in processing liquor can be associated with decrease in stock. Thus, when stock increases, ORE increase and vice versa. The process streams are sampled once per shift for GPL TTA as Na2O. These values when multiplied with the stock volumes give stock data as TTA as Na2O. The same data is used for ORE calculation. 30 | P a g e The GPL values fluctuate drastically during a shift. Thus, even small errors in measurement get magnified when multiplied with stock values and produce incorrect SRE, PME and ORE values. Period Feb-09 Mar-09 Apr-09 May-09 Jun-09 Jul-09 Aug-09 Sep-09 Oct-09 Dec-09 Jan-10 Feb-10 Mar-10 Apr-10 May-10 Jun-10 PME 102.69 96.41 94.93 95.33 98.88 98.64 108.11 103.6 101.39 103.04 103.89 103.26 97.22 94.77 92.49 88.42 SRE 89.58 93.87 98.55 97.86 94.99 94.53 85.91 90.62 93.98 90.5 91.44 92.29 97.22 101.29 102.42 106.68 ORE 91.99 90.50 93.55 93.29 93.93 93.24 92.88 93.88 95.29 93.25 95.00 95.30 94.52 95.99 94.73 94.33 120 100 80 60 40 20 0 Dec-08 Mar-09 Jul-09 PME y = -0.0092x + 466.33 R² = 0.0802 PME Linear (PME) Oct-09 Jan-10 May-10 Aug-10 Figure 5.1. PME versus Time plot 120 100 80 60 40 sre Linear (sre) SRE y = 0.0164x - 560.5 R² = 0.2338 Average 98.94 95.10 93.85 Coeffici ent of 0.08 0.233 0.564 Determi nation Table 5.1. PME, SRE and ORE over Time 20 0 Dec-08 Mar-09 Jul-09 Oct-09 Jan-10 May-10 Aug-10 Figure 5.2. SRE versus Time plot 97.00 96.00 95.00 94.00 93.00 92.00 91.00 90.00 Dec-08 Mar-09 Jul-09 ORE y = 0.0065x - 167.26 R² = 0.5649 ORE Linear (ORE) Oct-09 Jan-10 May-10 Aug-10 Figure 5.3. ORE versus Time plot The low coefficient of determination, R2 values signify high unexplained variations in SRE, PME and ORE values. 31 | P a g e 5.2. WBL SAMPLING For Soda recovery unit, the minimum GPL concentration is for incoming WBL, and thus highest volume. Also the GPL values of incoming WBL stream fluctuates heavily. Discrete sampling neglects these fluctuations and is based on assumption of uniform flow. Under failure of such assumption, the error is further highly magnified due to huge volumes. WBL GPL measurement was identified to be the bottleneck in SRE and thus ORE calculation. More frequent WBL samples were taken and analyzed with generally accepted GPL for a day to measure the variation in total WBL TTA and thus, variation in actual ORE to calculated ORE. Experiment: Frequent sampling of WBL from SFL and WFL for measuring TTA & RAA as Na2O and %solids for 2 days To study variation in WBL TTA, RAA and % solids. Analyzing effect of error in WBL GPL value on ORE Objective: Observation table and Results: For WFL: Day 1: 26th May 2010 Time 600 900 1030 1200 1400 1630 2200 AVG STD DEV Avg selected for a day GPL Error (Positive) Avg Stock m3 Total Error MT With Composite sampling the error is zero Avg for Pulp Mill Error (Positive) Total Error (g) Sample 1 2 3 4 5 6 7 Stream WFL WFL WFL WFL WFL WFL WFL (Na2O GPL) % Solids RAA Factor 17.02 6 2.5 16.56 7.3 2 16.9 7.94 1.5 16.18 7.62 2 15.24 7 2.5 12.2 5.39 5.5 15.86 7.3 8 15.2275 6.762292 1.55111 0.848317 16.04 6.766667 0.8125 0.004375 1350 1350 1.096875 0.005906 13 -2.2275 3007125 6 -0.76229 1029094 32 | P a g e 20 18 16 14 12 10 8 6 4 2 0 0 2 R² = 0.4123 % Solids RAA Linear (RAA) R² = 0.0053 Linear (RAA) 4 6 8 Day 2: 27th May 2010 Time 600 830 1030 1200 1400 1630 2200 AVG STD DEV Avg selected for a day GPL Error (Positive) Avg Stock m3 Total Error MT Sample 1 2 3 4 5 6 7 Stream WFL WFL WFL WFL WFL WFL WFL (Na2O GPL) % Solids RAA 15.8 6.6 17.57 8.25 14.4 7.93 15.7 7.61 14.5 6.6 15.07 8.56 15.48 6.6 15.44229 7.353958 0.986578 0.784098 15.26 -0.18229 1350 -0.24609 6.6 -0.75396 1350 -1.01784 TTA 31.7 41.98 36.39 36.81 31.7 38.75 34.4 35.79125 3.457622 32.6 -3.19125 1350 -4.30819 Factor 2.5 2 1.5 2 2.5 5.5 8 With Composite sampling the error is zero Avg for Pulp 13.07 Mill Error (Positive) Total Error (g) -2.37229 3202594 6 -1.35396 1827844 34.67 -1.12125 1513688 33 | P a g e 45 40 35 30 25 20 15 10 5 0 0 2 R² = 0.004 % Solids RAA TTA R² = 0.1801 Linear (% Solids) Linear (RAA) R² = 0.0042 4 6 8 Linear (TTA) For SFL: Day 1: 26th May 2010 Time 600 900 1030 1200 1400 1630 2200 AVG STD DEV Avg selected for a day GPL Error (Positive) Avg Stock m3 Total Error MT Sample 1 2 3 4 5 6 7 Stream SFL SFL SFL SFL SFL SFL SFL (Na2O GPL) % Solids RAA Factor 11.37 7 3 11.32 7.3 1.5 10.92 7.61 1.5 10.81 6.98 2 10.63 7.6 2.5 11.18 6.66 5.5 11.45 7.6 8 11.19813 7.239792 0.291906 0.350651 11.15 7.4 -0.04812 0.160208 3300 3300 -0.15881 0.528688 With Composite sampling the error is zero 14 12 10 8 6 4 2 0 0 2 R² = 0.0066 % Solids RAA R² = 0.0108 Linear (% Solids) Linear (RAA) 4 6 8 34 | P a g e Day 2: 27th May 2010 Time 600 830 1030 1200 1400 1630 2200 AVG STD DEV Avg selected for a day GPL Error (Positive) Avg Stock m3 Total Error MT Sample 1 2 3 4 5 6 7 Stream SFL SFL SFL SFL SFL SFL SFL % Solids 11.43 11.4 11.06 10.92 10.29 10.8 12.03 11.29938 0.512186 (Na2O GPL) RAA TTA 7 23.1 7.61 25.14 7.3 22.75 6.98 22 7.3 23.1 7.61 22.94 7.7 24.3 7.459583 23.47729 0.275402 0.97089 11.25 7.333333 23.5 -0.04937 -0.12625 0.022708 3300 3300 3300 -0.16294 -0.41663 0.074937 With Composite sampling the error is zero 30 25 20 15 R² = 0.0006 10 5 0 0 2 4 6 8 R² = 0.3019 R² = 0.0011 % Solids RAA TTA Linear (% Solids) Linear (% Solids) Linear (RAA) Linear (TTA) *While calculating Average GPL, weighted average is taken with weights equal to time gap between present and next sample. Calculation: Considering for 27th May, total error in Na2O TTA = -4.308 (WFL) + 0.075 (SFL) MT = -4.233 MT = 3300 ∗ 23.477 + 1350 ∗ 35.791 1000 3.365 % = 125.792 − 121.559 125.792 ∗ 100 = 3.5 % 35 | P a g e = 125.792 Thus, % error in WBL received = ℎ ,% Individual errors in WFL and SFL streams are: SFL WFL = = 8.92 % 0.1 % Assuming PME as 97 %, the error in ORE = 3.4 % Conclusion: Very low R2 values imply the high variability in WBL streams TTA, RAA and % solids value. Also, the analysis of error in sampling results 3.5 % in SRE and 3.4 % error in ORE. Thus, it is immediate requirement to adopt some other sampling method for correct calculation of SRE, PME and ORE and avoid per day fluctuations. Experiment 5.1. Frequent sampling of WBL from SFL and WFL 5.3. COMPOSITE SAMPLING There are different kinds of sampling methods: a. Grab Sampling / Discrete Sampling Advantage: Gives values of specific types of unstable parameters; No infrastructure cost Disadvantage: For highly varying values results can be very misleading due to huge errors; Human intervention b. Grab and composite sampling Advantage: Higher precision in sampling; No infrastructure cost Disadvantage: High labor hours are required; Human intervention c. Composite sampling Advantage: High precision in sampling; No human intervention Disadvantage: Moderate infrastructure cost; Issues of tank fouling d. Automation/online analyzer Advantage: High precision in sampling; Discrete values available instantly; Better process control Disadvantage: High infrastructure cost Grab sampling is presently followed by QC lab to analyze the samples. It has advantage that it gives values of specific types of unstable parameters like temperature at a given moment of time. But as experimental results have shown it gives large errors as fluctuations are large. In composite sampling sample is collected continuously with constant flow rate in a collection tank through sampling pipe. After every shift the liquor collected in sampling tank can be analyzed and average value can be noted down. 36 | P a g e The following design of the collection tank is proposed: SFL/WFL receive Discrete Sampling Point Overflow outlet Hot Water Temp. measurement device Valve head Sampling Point Agitator Drain Figure 5.4. Proposed collection tank design for WBL composite sampling After every shift sample is collected and the tank is emptied in BL pit. It is then washed with hot water to prevent fouling. Advantage and disadvantage: It has a limitation that composite liquor will be cooler than current measurement temperature i.e. 70 °C. Thus, new basis needs to be chosen. However, it has advantage that error in measurement will be negligible. Also the tank is designed keeping in mind the fouling problem. Significant design parameters: a. Hot water washing: To remove fouling due to deposition of WBL solids on cooling of WBL in the tank, hot water washing needs to be done for few moments after draining the tank. b. Valve head: it provides liquid for point temperature measurement. c. Agitators: With time WBL cools and solids start settling, thus, agitation helps in maintaining uniformity of the sample. In case, tank volume is reduced due to fouling then hot incoming liquor will float at top and may exit from overflow without mixing, thus, agitation helps in proper mixing. d. Composite sampling point: It is provided at an intermediate point where concentration can be assumed equal to general volume concentration. e. Temperature measurement device: It helps to record temperature of inlet stream. f. Discrete sampling point: Discrete samples can be taken, when required. g. Overflow outlet: In case of overflow or if due to fouling inside tank volume is reduced, the liquor flows to drain through overflow outlet. 37 | P a g e 5.4. AUTOMATION Online analyzers can be installed at WBL stream pipes that give value of TTA, RAA, temperature etc almost instantly. It gives value of measured variable almost instantly and can exactly measure the total amount of incoming black liquor as TTA. There are negligible errors and there is no human intervention. It is suggested to have a service tank where both SFL and WFL streams mix in desired proportion. Online analyzer measures the stream composition and helps to maintain desired flow rates to attain desired ratio. If streams are uniform the recovery process can be standardized easily and attainable performance can be reached. Also, operators can operate processes more uniformly as incoming stream composition is uniform. A list of suppliers for online Analyzers is prepared: a. b. c. d. e. f. Duralyzer-NIR [Canmark] Process NIR Analyzer [MODCON] kajaaniALKALi Alkali analyzer [Metso] Process Analytical systems Online TCC/TC Analyzer [AppliTOC] In-line Process Refractometer [Liquids Solids Control, Inc] A standard of minimum deviation in WBL measurements should be targeted. 38 | P a g e 6. MUD FILTER Figure 6.1. Lime mud filter flowsheet 6.1. LIME MUD CLARIDISC SYSTEM Figure 6.2. Vacuum disk filter sketch Figure 6.3. Vacuum disk filter in operation ClariDisc system consists of 3 meter diameter filter discs consisting of 18 separate sectors each mounted on the central barrel. The sectors are made of 316L stainless steel perforated plate and dressed with an underbag to improve liquor flow and an outer shrunk on filter bag of special polypropylene material. The outer layer of the cake is scrapped off the filter disc with a scrapper; the inner layer of lime mud is retained on the filter discs to act as a filtration precoat. HiPac system breaks the precoat and helps in its removal to prevent cake hardening. 39 | P a g e 6.2. MUD FILTER ORE LOSS The total amount of mud cake produces is not known, but the % composition of it is known. By using lime consumption data and % composition of mud cake, total quick lime produced can be calculated, The Mud cake sampling is done on composite basis to minimize the errors. Lime consumption data is taken from shift in-charge of both the units. The soda loss from Mud filters is calculated based on these data. Recausticizing reaction: CaO + H2O → Ca(OH)2 [74] + Na2CO3 → CaCO3 [100] + 2 NaOH In reaction between Ca(OH)2 and Na2CO3, Ca(OH)2 is the limiting reagent. Thus, the whole CaO that converts to Ca(OH)2 can be assumed to convert to CaCO3. As the concentration of impurities in mud cake is very low, the dry solids in mud cake can be assumed to be 100% limestone. CaO Initial Final A yX/100 → CaCO3 0 (A – yX/100) * (100/56) X = mass of dry solids y = % CaO in dry mud Now, (A – yX/100) * (100/56) = X; Thus, X can be calculated And if z = % TTA as Na2O, Total TTA as Na2O = Zx/100 Data table 6.1, 6.2, 6.3, and 6.4 in Appendix A The combined loss from Recovery 1 and Recovery 2 of the total soda loss through MUD CAKE in MUD FILTER is 7.232 %. The corresponding loss in ORE from Recovery 1 and Recovery 2 through MUD CAKE in MUD FILTER is 0.677 %. The combined loss from Recovery 1 and Recovery 2 of the total soda loss through GRIFTS and STONES is 0.269 %. The corresponding loss in ORE from Recovery 1 and Recovery 2 through GRIFTS and STONES is 0.035 %. The combined loss from Recovery 1 and Recovery 2 of the total soda loss through MUD CAKE in MUD FILTER and GRIFTS and STONES is 7.232 %. The corresponding loss in ORE from Recovery 1 and Recovery 2 through MUD CAKE in MUD FILTER and GRIFTS and STONES is 0.677 %. A standard of 0.3% TTA as Na2O and 1% Ca(OH)2 by weight in Mud cake should be sought. 40 | P a g e 6.3. PROCESS PARAMETER TESTING Based on information collected through journals and case studies and on discussion with experts, a few process parameters that could affect the performance of mud filter were analyzed. The parameters are: a. b. c. d. e. f. g. h. i. j. Vacuum Precoat mud cake thickness Vat solid composition Vat solid concentration % Moisture content Homogeneity in vat mixture Temperature Disc RPM [Retention time] Pre-Scrapper washing [Displacement washing] Proper disc cleaning/Disc maintenance 6.3.1. VACUUM For proper process the pressure should be close to 550 mmHg vacuum. The vacuum is manually controlled through vacuum pump. The pressure kept is 530-560 mmHg, which is ideal requirement. 6.3.2. PRECOAT MUD CAKE THICKNESS Less thickness would imply better effective pressure and better moisture control. The operation is done with mud cake thickness of 10 mm approximately. The designed value is 12 mm. 6.3.3. VAT SOLID COMPOSITION Vat solid sampling is done to quantify the % TTA as Na2O, % CaO and % Moisture in the mud cake. The results are discussed later. Minimum % TTA, % CaO and % Moisture are desirable. 6.3.4. VAT SOLID CONCENTRATION In ideal condition, the vat solid concentration should be 15-18% solids. There are 3 points of dilution of feed from Mud Washer 2. First, a hot water stream dilutes the feed to 1.12-1.13 kgpl; this is maintained by an autovalve. Second, the hot water from HiPac system, used to scrap mud cake from filter, dilutes vat. Third, to maintain vat level hot water dozers are placed at bottom, however, they rarely open. Vat solid concentration sampling is done and results are discussed later. 6.3.5. % MOISTURE CONTENT Lower the moisture implies lower the dissolved alkali content in a sample of mud cake. The % moisture in mud filter in recovery 1 is around 50, while in recovery 2 is 45. It is considerably high and should be reduced to 35-40%. Moisture content could be reduced by lowering disc RPM or lowering cake thickness 41 | P a g e 6.3.6. HOMOGENEITY IN VAT MIXTURE As pressure is uniform across disc, homogeneity of vat solution is important for uniform functioning of disc. Vat homogeneity sampling is done and results are discussed later. 6.3.7. TEMPERATURE Ideally, vat temperature should be 72-75 °C. Temperature results are discussed later. 6.3.8. DISC RPM Disc RPM is kept at 85%. It could be decreased to provide sufficient time for moisture absorbance. 6.3.9. DISPLACEMENT WASHING The rising side of the disc should be washed with hot water to facilitate displacement washing and thus reduction content in the mud cake. Samples are taken at different flow rates of washing; results are discussed later. 6.3.10. PROPER FILTER DISC CLEANING As silica content is high in vat, around 8% as compared to wood based plants as 3%, choking of pores is more frequent. Cleaning is done with hot water once in every shift. Once in every 2 or 3 weeks cleaning is done though acid. Experiment: Mud cake (from Mud filter of recovery 2) sampling to test % Moisture, % TTA as Na2O and % Ca(OH)2. Grits tested for % TTA as Na2O and % Ca(OH)2. To analyze variation in mud cake composition that could adversely affect mud filter performance. Also, to confirm the values of % TTA for ORE calculations Objective: Observation table: Co de % Moist ure Time Sample W1 W2 W3 % TTA as Na2O Dry wt g 11.03 8.32 9.58 m 1.7 1.4 1.5 % TTA % 0.44 0.45 0.44 0.32 0.93 0.91 Dry wt % Ca(OH)2 p 6.7 4.5 4.1 % 5.27 3.84 2.85 2.02 3.2 3.4 Units Hours 930 1100 1500 930 1100 1500 1MC 2MC 3MC 1G 2G 3G g 47.87 49.02 48.32 49.01 50.14 47.28 G 65.7 71.21 70.4 103.89 69.18 71.28 g 57.57 61.62 60.15 93.28 65.14 65.65 W 5 M N E 3 % 45.6 43.21 46.42 23.97 21.22 23.47 4.38 3.79 4.92 42 | P a g e Conclusion: `The % TTA is around 0.45, approximately same as generally reported by QC laboratory. However, % Ca(OH)2 value is highly different and highly varying as well. The excess presence of lime decreases cake porosity and thus higher amount of alkali is retained in mud cake. The inefficient process of lime addition in slaker results in highly varying concentrations of lime in the liquor that adversely affects the performance of the Mud filter. Causticizing control models are discussed later. Experiment 6.1. Mud cake sampling from Mud filter of Recovery 2 Experiment: Vat and Mud sampling to test for % Solids, Twaddell, GPL TTA as Na2O, % Ca(OH)2 and Temperature at different zones in vat and mud filter To analyze vat solid concentration, homogeneity in vat and mud cake and temperature of vat Objective: Theory: The vat samples were taken at 3 different zones from vat to check for homogeneity. Zone A is deadzone with little turbulence, zone B is central volume, and zone C is highly turbulent just above feed inlet. AP BP A C Disk Vat B INLET 43 | P a g e Observation table and Results: Vat Homogeneity Sampling Time 1045 1045 1045 STD DEV 1300 1300 1300 STD DEV 1600 1600 1600 STD DEV Sample A1 B1 C1 A2 B2 C2 A3 B3 C3 % Solid 12.42 15.69 13.4 12.12 19.57 29.34 30.81 22.99 23.36 21.05 20.64 6.76 40 30 20 10 0 0 2 4 Sample 1 Sample 2 Sample 3 Twaddell 18 24 19 15.80 24 26 22 8.3 27 26 27 2.16 TTA (Na2O GPL) 1.84 2.27 1.97 10.88 2.46 2.4 2.4 1.43 2.21 2.77 2.58 11.30 Ca(OH)2 (%) 3.23 2.15 2.55 20.65 1.61 1.42 1.42 7.39 2.02 1.55 1.9 13.39 Temp (°C) 65 Avg % Solid 13.83 65 26.57 64 21.68 31.04 % Solid 4 3 2 1 0 0 2 4 % Ca(OH)2 Sample 1 Sample 2 Sample 3 3 2.5 2 1.5 1 0.5 0 0 2 4 TTA (GPL) Sample 1 Sample 2 Sample 3 Mud Cake Homogeneity Time Sample % Moisture 1045 AP1 41.88 1045 BP1 42.73 STD DEV 1.42 1300 AP2 46.7 1300 BP2 49.96 STD DEV 4.76 TTA, % Na2O 0.347 0.357 2.00 0.483 0.447 5.47 44 | P a g e 0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 0.483 0.447 0.347 0.357 Sample 1 Sample 2 52 50 48 46 44 42 40 0 1 49.96 46.7 42.73 Sample 1 Sample 2 41.88 2 2 3 3 Conclusion: a. The % Solid variation is huge. It should remain between 15-20 % for proper moisture absorbance. The last 2 observations were taken with autovalve maintaining density of 1.135 kgpl, and first observation was taken with 1.12 kgpl. Density (solid phase) of limestone = 2.25 gcm-3; thus, K = 1.8 Thus, for 1.135 kgpl, %Solid = 21.41 % & for 1.12 kgpl, % Solid = 19.28 % Glossary: Twaddell: % Solid and Density: It helps to measure density instantly. To convert °Tw to kg/l or gcm-3, remove the decimal and 1 before it. Multiply the rest with 2. E.g. 1.12 kg/l = 24 °Tw. % −1 = = , = = ℎ b. There is contrasting difference in concentrations at different zones in vat and mud cake. The difference in vat concentration result in non-uniform mud cake formation on mud filter and thus, performance of the filter suffers. However, the deviations are minimized over mud cake as disk passes through huge volumes. The %Standard Deviations are calculated that give standard deviation over average of that quantity. A proper agitation system needs to be installed to maintain homogeneity and reduce alkali loss. Such system is installed in Drum filter of Recovery 1. The temperature of vat solution is 65 °C, but it should be 72-75 °C. The feed to the Mud filter is received from LMS tank, which is dozed by hot water to maintain required density. LMS tank has supply of steam from power boiler (Pr. 4.55 atm and temp. 150 °C). With complete opening of steam valve the temperature inside LMS tank is 70 °C, thus it cannot be further increased. There is no steam line in Mud filter. The hot water is received from evaporator at approximately 67-70 °C. The reason of loss in temperature from LMS to vat is due to presence of no insulation of feedline to Mud filter. By providing insulation temperature can be kept at around 70 °C. c. Experiment 6.2. Vat and Mud sampling to test homogeneity from Mud filter of Recovery 2 g e 45 | P a A washer system is installed in the mud filter that is used to clean the disk. The same washer can be used with less flowrate during process for displacement washing. The experiment was conducted with different flowrates of washing. Experiment: Objective: Calculation of % TTA as Na2O at different flowrates of washing To analyze effect of displacement washing on Mud cake at different flowrates of washing Observation table and Results: Day 1 Sample A1 A2 Flowrate (%) 0 20 % Moisture 50.63 48.97 TTA (NA2O %) 0.543 0.34 % Reduction 37.39 Cumulative % Reduction 37.38 Day 2 Sample B1 B2 B3 B4 B5 Flowrate (%) 0 10 20 30 40 % Moisture 48.58 48.76 48.54 48.41 48.28 TTA (NA2O %) 0.796 0.442 0.478 0.486 0.423 % Reduction 44.47 39.94 38.94 46.85 Cumulative % Reduction 44.472 -8.14 -1.67 12.96 Day 3 Sample C1 C2 C3 C4 C5 Flowrate % (%) Moisture 1 10 20 30 40 43.52 43.71 45.76 46.78 47.4 TTA (Na2O % ) 0.61 0.51 0.55 0.5 0.56 % Reduction 16.39 9.83 18.03 8.19 Cumulative % Reduction 16.39 -7.84 9.09 -12 46 | P a g e % Moisture - B 48.8 48.6 48.4 48.2 0 20 48.76 48.58 48.54 48.41 48.28 40 60 48 47 46 45 44 43 0 % Moisture - C 47.4 46.78 45.76 % Moisture 43.71 43.52 20 40 60 % Moisture % TTA Na2O - B 1 0.8 0.6 0.4 0.2 0 0 20 40 60 0.442 0.478 0.486 0.423 % TTA 0.2 0 0 0.796 0.8 0.6 0.4 0.61 % TTA Na2O - C 0.51 0.55 0.5 0.56 % TTA 20 40 60 *Composite sampling is done to minimize variation due to non-homogeneity. Conclusion: There is considerable reduction in alkali content on displacement washing. However, the curve is not linearly decreasing as assumed; thus, there is no considerable difference on increasing the flowrate. There is no major difference in % Moisture content of mud cake on washing, thus, most of the water reabsorbed by mud cake is extracted back with filtrate. The effects of displacement washing can be increased by increasing the porosity of the cake. Lime mud cake has very less porosity and thus, displacement washing is not much effective. Considerable decrease in moisture content on displacement washing can be achieved by using Filter Aids. Principle types of Filter Aids include Diatomaceous Earth (DE), Perlite, cellulose and Rice hull ash. Each type has its own characteristics, advantage and disadvantages. NALCO supplies filter aids for mud washing in lime mud filters with a product code NALCO 7560. It is a surfactant based filter aid, which is currently used by BILT and ITC. The feed is very small as 200g/T i.e. 0.02% by wt. Thus, there is no increase in impurity of mud cake. Also it evaporates at 800 °C and thus, will not stick on walls of lime kiln, if operated. Experiment 6.3. Displacement washing in mud filter of Recovery 2 47 | P a g e 6.4. CAUSTICIZING CONTROL MODELS In the slaker the amount of lime to be added depends upon causticizing efficiency required and feed TTA (as Na2O). Presently, the operator measure the °Tw in inlet GL and keeping the °Tw difference to a certain value depending upon GL TTA in slaker outlet, adds lime. The lime addition is manually controlled and temperature variation provides information to operator when to stop adding further lime. GL TTA °Tw difference 92-93 8 85-86 9-10 The objective is to maintain TAA above 80. But causticizing efficiency is compromised and this leads to excess lime addition in the system. 6.4.1. CAUSTICIZING EFFICIENCY TTA is measured in lab once in 2 hours (as done presently). TTA and density (Twaddell) are used to calculate a conversion factor for converting TTA values into density (Twaddell) and vice versa. The conversion factor is calculated form results in the previous 8 or 24 hours. Now, based on Goodwin’s curve the degree of causticizing is decided. The sulfidity can be taken as 5% (based on general observation). TTA (Na2O GPL) CE% 80 89 85 88 90 87 95 87 100 86 105 85 The NaOH (GPL Na2O) can be related to continuous temperature difference measurement and density (Twaddell) measurement, verified by titration results. 6.4.2. GREEN LIQUOR CONTROL AND CAUSTICIZING CONTROL In this model the incoming GL is made uniform by WWL dozing. The TTA is maintained at around 85 GPL as Na2O. The corresponding CE% is 88 and NaOH GPL as Na2O is 70. Particular lime feeding rate can be noted based on temperature and density. Uniform lime feeding needs to be done. 6.4.3. ADVANCED CAUSTICIZING CONTROL WITH KAJAANI ALKALI In causticizing control there are 2 different control loops, GL TTA control and WL CE% control. GL TTA control stabilizes the TTA value of GL flowing to the slaker. WL CE% control stabilizes the causticizing degree of produced white liquor. The CE% of lime milk is used as a short feedback signal to the dT controller. Recovery 2 doesn’t have a proper lime feeding system and it’s presently manually controlled. In order to switch on to advanced control, the feeding system needs to be automated as well. Metso Kajaani Causticizing Control and Kajaani Alkali Analyzers are 2 such causticizing control models supplied by Metso. 48 | P a g e 7. 7.1. PULP MILL SODA CARRYOVER PULP MILL SODA CARRYOVER ORE LOSS Data table 7.1, 7.2 and 7.3 in Appendix A The loss through SODA CARRYOVER WITH PULP in SFL from total soda losses is 36.75 %. The loss through SODA CARRYOVER WITH PULP in WFL from total soda losses is 32.84 %. The corresponding loss in ORE in SFL as SODA CARRYOVER WITH PULP is 4.975 %. The corresponding loss in ORE in WFL as SODA CARRYOVER WITH PULP is 5.427 %. The combined loss through SODA CARRYOVER WITH PULP in SFL and WFL from total soda losses is 69.59 %. The corresponding loss in ORE in SFL and WFL as SODA CARRYOVER WITH PULP is 5.108 %. The losses from Soda carryover with pulp in SFL and WFL lines are huge and solutions must be sought for reduction in these losses. The solutions are discussed later in this section A standard of 8-10 kg/MT of TTA as Na2O as soda carryover with pulp in both SFL and WFL individually needs to be targeted. 49 | P a g e 7.2. PULP MILL PRODUCTION VERSUS SODA CARRYOVER LOSSES Soda carryover as kg/MT TTA as Na2O for WFL is very high. It is suggested that as the WFL production has increased, Soda carryover as kg/MT has also increased manifold. Soda carryover versus Production curves are plotted for SFL and WFL and their relationship is studied. Data table 7.4 and 7.5 in Appendix A For WFL, Production 1000 800 600 400 Linear (Production) 200 0 03-Dec 22-Jan 13-Mar 02-May 21-Jun y = 0.5626x - 21966 Production Figure 7.1. Production versus Time in WFL Soda carryover 30 25 20 15 10 5 0 03-Dec 22-Jan 13-Mar 02-May 21-Jun Linear (Soda carryover as kg/MT) y = 0.0859x - 3437.6 Soda carryover as kg/MT Figure 7.2. Soda carryover as kg/MT of unbleached pulp versus Time in WFL 50 | P a g e Production and Soda Carryover 900 800 700 600 500 400 300 200 100 0 03-Dec 22-Jan 13-Mar 02-May 30 25 y = 0.5626x - 21966 20 15 10 5 0 21-Jun Weekly Production Soda Carryover as kg/MT Linear (Weekly Production) y = 0.0859x - 3437.6 Figure 7.3. Production and Soda carryover versus Time in WFL Soda Loss vs Production 50 45 40 35 30 25 20 15 10 5 0 500 550 600 650 700 750 800 Linear (% Soda Loss vs Production) y = 0.0301x - 2.0499 R² = 0.1547 % Soda Loss vs Production Figure 7.4. Soda carryover versus Production in WFL 51 | P a g e For SFL, Production 1800 1600 1400 1200 1000 800 600 400 200 0 03-Dec 22-Jan 13-Mar 02-May 21-Jun y = 1.2705x - 49723 Production Linear (Production) Figure 7.4. Production versus Time in SFL Soda carryover 40 35 30 25 20 15 10 5 0 03-Dec 22-Jan 13-Mar 02-May 21-Jun y = -0.0013x + 68.687 Soda carryover as kg/MT Figure 7.5. Soda carryover as kg/MT of unbleached pulp versus Time in SFL 52 | P a g e Production and Soda Carryover 1800 1600 1400 1200 1000 800 600 400 200 0 03-Dec 22-Jan 13-Mar 02-May 5 0 21-Jun y = -0.0013x + 68.687 25 20 15 10 35 30 y = 1.2705x - 49723 Production Soda Carryover as kg/MT Linear (Production) Figure 7.6. Production and Soda carryover versus Time in SFL Soda Loss vs Production 40 35 30 25 20 15 10 5 0 500 700 900 1100 1300 1500 1700 1900 Linear (% Soda Loss vs Production) y = -0.0009x + 17.369 % Soda Loss vs Production Figure 7.8. Soda carryover versus Production in SFL A standard of constant soda carryover with production is targeted. 53 | P a g e Observation (WFL): The production has risen over last few months but soda loss as kg/MT has also risen very swiftly over the same period. Observation (SFL): There has been an increase in production, but the soda loss has remained constant over the same period. Conclusion: As soda loss as kg/MT is rising with production, it shows the maximum capable load of washers has been reached. Further increase in production affects the washer performance. It is necessary that steps should be taken to improve the efficiency of washers to make them capable of handling the increased load. Else, new washers need to installed in the process line to reduce the load on individual washers. On the other hand, for SFL, the operation is within the maximum capable load of washers and even an increase in production doesn’t affect the washers’ performance. 7.3. WASHER EFFICIENCY FOR SFL AND WFL Figure 7.9. Brown Stock Washer 54 | P a g e Presently, Soda carryover as kg/MT of unbleached pulp TTA as Na2O for SFL is around 15 and for WFL is around 24. It is necessary to further reduce the soda loss as it contributes approximately 70% to the total soda loss in the system. Various steps can be taken to reduce soda loss from washers. Presently 2 projects are going on, one in each, in SFL and WFL to reduce soda loss by increasing the efficiency of washers. Solutions given in WFL are maintaining proper vat concentration, proper nozzle (for displacement washing) flow rate, maintenance of nozzles and proper vacuum. In SFL, the project is focused on increasing the vacuum in the washers, which are inefficient presently. 7.3.1. TOTAL WASHABLE ALKALI AS SODA CARRYOVER IN WFL It was suggested that the increase in loss in WFL is due to increase in bound soda loss and it cannot be retrieved. Elemental analysis of washed pulp is conducted to calculate washable alkali in the sample. Thus, % of bound alkali to total alkali is calculated. Experiment: Elemental analysis of filtrate of thoroughly washed pulp from final washer in WFL to calculate total washable alkali as kg/MT of dry unbleached pulp TTA as Na2O. To calculate total washable alkali in a sample of pulp from final washer Objective: Observation table and Results: Sample Wet Wt Dry Wt Vol. of Solution Density Wt. of solution PPM g TWA1 g ml 1000 g/ml 0.9758 g 975.48 15.8 0.0154 0.0208 14.79 Na g as Na2O TWA kg/MT TTA as Na2O 10.701 1.626 Total soda carryover as kg/MT TTA as Na2O for same sample is 24.19 and % Moisture is 84.8. Thus, % washable alkali = 62.87 of total soda carryover in unbleached pulp. Conclusion: A large percentage of total soda carryover in unbleached pulp is washable and can be retrieved. Experiment 7.1. Analysis of total washable alkali in washed pulp in WFL 55 | P a g e 8. 8.1. PULP MILL REJECT PULP MILL REJECT ORE LOSSES 8.1.1. TOTAL SODA LOSS CALCULATIONS To calculate soda losses from pulp mill reject the amount of reject and its composition is required to be known. There are 3 reject streams in SFL. The total reject is 1.2 % of unbleached pulp. The ratio of reject from these exit streams is: Screen 1 (Thick mesh) : Sand Box : Screen 2 (Thin) = 0.35 : 0.15 : 0.50 There are 2 reject streams in WFL. The total reject is 1 % of unbleached pulp. The ratio of reject from these exit streams is: Vibratory Screen (Thick) : Pressure Screen (Thin) = 0.42 : 0.58 Samples were collected from the reject streams in SFL and WFL respectively with weights from different streams in the ratio of their reject ratio. Experiment: Objective: Reject stream analysis for TTA as Na2O in kg/MT of dry sample rejected To calculate TTA as Na2O in kg/MT for ORE loss calculation Observation table and Results: For SFL, Sample % Moisture % 82.29 82.77 80.72 81.31 Wet wt g 11.988 11.405 D11 D12 D21 D22 For WFL, Sample TTA (as Na2O in kg/MT) Dry wt m g ml 6.8 7.2 1.381 3.221 TTA kg/MT 49.2 56.27 52.79 52.76 % Moisture % 68.71 63.02 64.10 68.21 Wet wt g 8.32 7.97 D11 D12 D21 D22 TTA (as Na2O in kg/MT) Dry wt m g ml 13.56 16.10 4.597 2.068 TTA kg/MT 80.06 83.95 52.79 52.76 TTA as Na2O in kg/MT for SFL is 52.76 and for WFL is 81.82. Experiment 8.1. Reject stream analysis for TTA in WFL and SFL 56 | P a g e 8.1.2. TOTAL WASHABLE SODA LOSS CALCULATIONS Experiment: Elemental analysis of filtrate of thoroughly washed pulp from reject streams to calculate total washable alkali as kg/MT of dry unbleached pulp TTA as Na2O. To calculate total washable alkali in a sample of pulp from reject stream Objective: Observation table and Results: Sampl e Unit Form ula A Wet wt g B Sol. Density g/ml C Sol. Wt g 100 0*B D Dry wt g H Na PPM I g H* (C/10 ^6) E Na as Na2CO3 g I*(53/2 3) F Na as Na2O g I*(31 /23) 0.153 0.154 0.311 0.038 0.232 0.061 0.235 0.068 G % Moist % [1(D+E) /A]*1 00 85.65 71.57 73.5 74.13 82.73 76.32 68.28 69.71 TWA as Na2O kg/MT [F/(E+D) ]*1000 117.440 TWA avg kg/MT S Thick 117. 9.096 0.966 966 1.042 0.114 0.262 1 6 S Thin 120. 20.026 0.952 952 5.429 0.115 0.264 1 4 WThic 11.079 0.97 970 2.404 238 0.231 0.532 k1 W Thin 7.676 0.968 968 1.922 28.9 0.028 0.064 1 S Thick 178. 10.616 0.963 0.172 0.396 963 1.112 2 6 S Thin 8.381 0.978 978 2.213 46.3 0.045 0.104 2 WThic 178. 9.612 0.979 979 2.118 0.174 0.402 k2 1 W Thin 14.781 0.959 959 2.927 52.6 0.050 0.116 2 *For average TWA, the weights are taken as equal to reject ratio. 50.990 27.136 105.981 55.3 18.981 153.690 50.82 26.337 93.265 57.28 22.345 Conclusion: Assuming the total soda content same as for previously done sampling, % Soda as washable with respect to total soda are: SFL: WFL: 96.54% 68.96% 57 | P a g e Thus, a large fraction of soda rejected in the reject stream can be retrieved by hot water washing. Assuming that we can retrieve 50% of washable alkali content, then we soda washable in SFL is 24.45 kg/MT and in WFL 28.145 kg/MT. Thus, % alkali retrieved of total alkali content is: SFL: WFL: 48.27% 34.48% Average pulp loss through reject in MT (from June 1 to June 17): SFL: WFL: Thus, % Alkali that can be retrieved, = 48.27 ∗ 2.369 + 34.48 ∗ 1.399 2.369 + 1.399 2.369 MT 1.399 MT = 43.15 % Thus, Reduction in ORE, = (0.4315) * 0.201 = 0.087 % Or, New ORE loss, = 0.114 % Experiment 8.2. Analysis of total washable alkali in pulp from reject stream in WFL and SFL Based on above data, ORE losses are calculated for Reject stream in SFL and WFL. Data table 8.1 and 8.2 in Appendix A The total soda loss as SODA CARRYOVER WITH REJECT in SFL and WFL from total soda losses is 2.81 %. The corresponding total soda loss in ORE as SODA CARRYOVER WITH REJCT in SFL and WFL is 0.201 %. The total washable soda loss as SODA CARRYOVER WITH REJECT in SFL and WFL from total soda losses is 2.34 %. The corresponding total washable soda loss in ORE as SODA CARRYOVER WITH REJCT in SFL and WFL is 0.167 %. A standard of reduction of loss in ORE from Reject to 0.1 % should be set. 58 | P a g e 8.2. REJECT STREAM WASHING The reject streams in SFL and WFL are thoroughly studied and measures are suggested to decrease soda loss. To reduce washable soda loss in reject stream principle solutions are hot water alkali washing and pressure drying for reduction in moisture content. The devices related to reject stream in SFL line are HD (High density) Cleaner, Delta Knotter, Delta Screen, Opti Screen, Centricleaner and Vibratory Screen. The devices related to reject stream in WFL line are Vibratory Screen, Pressure Screen and Centricleaner. For SFL, Blow tank Pulp + liquor Filtrate tank 1 [Conc. WBL] Liquor for dilution HD Cleaner Accept Reject [Sand] Sand Box (Mixed with Reject from Centricleaner and thrown out) Liquor for dilution Liquor for washing Delta Knotter Reject Accept Washer 1 & 2 Accept tank Accept Vibratory Screen [Thick mesh] Reject [Wood chips, uncooked waste] Thrown out Blow tank Figure 8.1. HD Cleaner, Delta Knotter and Vibratory Screen in SFL HD Cleaner is a centrifugation based filtering device similar to cyclone separator but for liquids. High density sand is settled at bottom and accept comes from top. In the system as there is no pressure drying moisture content is very high in reject and thus soda content is high. Also, concentrated liquor of Filtrate tank 1 is used which has highest BL content of all Filtrate tanks. Delta Knotter has pressure screens. High pressure difference in inlet and outlet pushes material through the screen. Again, washing is done with liquor from Filtrate tank 1. Vibratory Screen [Delta Knotter stream] receives reject from Delta Knotter, where vibratory action filters the pulp. The reject falling down is washed with liquor from Filtrate tank 1 that increases moisture and alkali content of the reject. 59 | P a g e Figure 8.2. HD cleaner Figure 8.3. Delta Knotter Figure 8.4. Vibratory Screen Press 1 Low Consistency Tank Delta Thickener Accept Liquor for dilution Liquor for dilution Delta Screen Reject Accept Centricleaner [Pri-Sec-Ter-Quar] Filtrate tank 3 Liquor for dilution Opti Screen Reject Accept [Sand] Reject LC tank Sand Box Liquor for washing Vibratory Screen [Thin mesh] Reject [Shives] Accept Dump tank Thrown out Figure 8.5. Delta Screen, Opti Screen, Centricleaner and Vibratory Screen in SFL Delta Screen and Opti Screen are similar to Delta Knotter but the screens are thin. Also, a pressure plug, moved by a rotor pushes material through screen. The outlet is dry but the moisture content is increased on washing at Vibratory Screen. Centricleaner is based on principle same as cyclone separator. In the 4 units, pulp and paper flow counter wise. 60 | P a g e For WFL, Blow tank Filtrate tank 1 [Conc. WBL] Liquor for washing Vibratory Screen Accept Washer 1 Reject [Uncooked waste] Thrown out Figure 8.6. Vibratory Screen in WFL The alkali content in reject from vibratory screen is very high as there is no washing or pressure drying. Figure 8.7. Centricleaner Figure 8.8. Delta Screen Figure 8.9. Pressure Screen Washer 3 Liquor for washing Accept Filtrate tank 4 Centricleaner [Pri-Sec-Ter-Quar] Reject Pressure Screen Reject Washer 4 Dilution tank Vibratory Screen [Shives] Thrown out Figure 8.10. Pressure Screen, Centricleaner and Vibratory Screen in WFL 61 | P a g e Solutions suggested to reduce alkali loss from reject stream are: a. Hot water header for washing Instead of using liquor for washing the pulp in Vibratory Screens and especially liquor from Filtrate tank 1, a common hot water header can be made that takes its feed from hot water tank used to wash pulp in final washer or press. To avoid increase in hot water consumption and black liquor dilution, the Accept can be fed back to the hot water tank. Hot water tank Hot Water Header Hot water for washing Vibratory Screen [Thick mesh] Vibratory Screen [Thin mesh] Sand Box Accept Figure 8.11. Hot water header for washing b. Parallel cleaning in Centricleaner Presently, flow in centricleaner bodies is anti-parallel. The liquor in the first stage gets highly concentrated. To incorporate soda washing in the process, a system of parallel flow of liquor into the different bodies can be provided. c. Pressure filter dryer A pressure filter dryer can be installed common to both SFL and WFL. In these dryers, the reject streams are first washed with hot water. They are then dried by applying pressure. Thus maximum washable alkali can be extracted. The required size of such dryers is less considering the load. Thus, the capital cost is not too high. Further, depending upon the extent of alkali washing, best suitable size can be selected. Some of the suppliers of such filters are: a. 3Di Equipment Ltd b. Dhananjaya Global Business Solutions c. GEA Barr-Rosin Inc. d. Aeroglide Corporation e. MET-CHEM Inc. f. Bhagwati Machines India Pvt Ltd g. Arjun Technologies (I) Ltd 62 | P a g e 9. ESP – ELECTROSTATIC PRECIPITATOR ESP PHOTO!! Figure 9.1. ESP Electrostatic precipitator (ESP) essentially consists of 2 sets of electrodes, viz. collecting electrodes and emitting (discharge) electrodes. These two electrodes are arranged in alternate rows. A unidirectional high voltage from a rectifier is applied between these 2 electrodes, connecting its negative polarity to the emitting electrodes and the positive polarity to the collecting electrodes which are earthed. Because of physical configuration field in the neighborhood of the emitting electrode is very high. The dust laden flue gas from boiler passes between rows of collecting and discharge electrodes. The gas molecules which are normally neutral are ionized due to the presence of high electric field. The positive charges of the ions created travel towards the discharge electrodes and the negative charges (ions and electron) towards the collecting electrodes. On the way to the collecting electrode, the negative charges get attached to the dust particles. Thus the dust particles are electrically charged. In the presence of high electric field between emitting and collecting electrodes the charged dust particle experience a force which causes the particles to move towards the collecting electrodes and finally get deposited on them. A minor portion of dust particles which have acquired positive charges get deposited on the emitting electrodes also. Periodically these particles are dislodged from the electrodes by rapping the electrodes. The particles then fall into the bottom from where they are removed by the ash deposal system. 63 | P a g e Various parts of the precipitator are: a. b. c. d. e. f. g. Precipitator chamber Discharge system Collecting system Gas distribution system Dust conveying system Flue gas valve Rectifier-Transformers 9.1. BHEL ESP SYSTEM Design Value 31.45 170 16 75 99.53 3 25 0.66 14.65 8 25 for field 1 and 21 for field 2 and 3 97.68 Table 9.1. BHEL ESP Design Conditions Unit m3/s °C g/Nm3 mg/Nm3 % Units mmWC m/s s Units Units s/m Design Parameter Gas Flow rate Inlet Temperature Inlet dust concentration Outlet dust concentration ESP efficiency No. of fields in series Press. drop across precipitator Gas velocity (inside ESP) Treatment time No. of collecting electrode in a row in a field No. of rows of CEs per field Specific collection area 64 | P a g e 9.2. PROCESS PARAMETERS The parameters are divided as constant and variable parameters based on the scope of variation in their values in the installed ESP at Recovery unit in Abhishek Industries. Constrained/constant parameters are: a. b. c. d. e. f. Aspect ratio; Height, length and spacing of collection plate i.e. crossection area of ESP Diameter of entering particles Gas uniformity/Gas distribution No. and type of discharge electrodes and collection plates Sneakage Particulate size distribution Variable parameters are: a. b. c. d. e. f. g. h. i. j. k. l. m. Gas flow rate; Treatment time; Velocity Temperature Moisture Gas composition [Flue gas conditioning] Gas viscosity ESP ash composition Peak Voltage; Spark rate; Energization Pressure drop Resistivity Re-entrainment Specific Collection Area Inlet dust load Effectiveness of dust removal system Many of the above mentioned parameters are inter-related. All the parameters can be reduced to 5 basic variables: a. Collection Efficiency Theoretical collection efficiency is given by Matts-Ohnfeldt equation6, 6 Rose, H. E., and A. J. Wood. An Introduction to Electrostatic Precipitation in Theory and Practice 65 | P a g e Or, Certain values like particle size distribution and gas viscosity could not be calculated, thus, theoretical collection efficiency could not be calculated. Practical collection efficiency is calculated from inlet dust concentration and outlet dust concentration of an ESP under process. Practical Collection Efficiency, = Practical Collection Efficiency calculations are done and results are discussed later. *100 b. Resistivity Resistivity, which is a characteristic of particles in an electric field, is a measure of a particle's resistance to transferring charge (both accepting and giving up charges). Resistivity is a function of a particle's chemical composition as well as flue gas operating conditions such as temperature and moisture. Particles can have high, moderate (normal), or low resistivity7. 7 Rose, H. E., and A. J. Wood. An Introduction to Electrostatic Precipitation in Theory and Practice 66 | P a g e Table 9.2. ESP characteristics with Resistivity; Source: Adapted from U.S. EPA 1985 Fly ash from Recovery boilers tends to have a good resistivity. The reason for this good resistivity comes from the chemistry of the process. Typical alumina (Al2O3) and silica (SiO2) content (which are poor electrical conductors) is high. Also since combustion is commonly done with a wet fuel in a mass type firing mode, it typically generates a higher level of conductive carbon in the ash. Lastly, the surface moisture of the fuel and inherent hydrogen in cellulose, cause the flue gas to have appreciable moisture (typically 15-25%). This flue gas moisture tends to give some "surface conditioning", or a conductive liquid film to the particulate. These factors result in "good" resistivity for ESP ash8. Resistivity measurements could not be done in laboratories of the company. The company can send sample for resistivity to some other labs which will provide important information on flue gas characteristics. Also, the reason of ash build up on ESP and frequent conveyor failures can be high resistivity of ESP ash that means high cohesivity. Thus, the correct reason for current problems in ESP can be known. 8 Prakash H. Dhargalkar, Jose Astolphi, Jr. Advancements in air pollution control for pulp and paper industry 67 | P a g e c. Specific Collection Area (SCA) The specific collection area (SCA) is defined as the ratio of collection surface area to the gas flow rate into the collector. Most conservative designs call for an SCA of 20 to 25 m2 per 1000 m3/h to achieve collection efficiency of more than 99.5%. Total collection area in Recovery 1 = 3276.8 m2 [(48*8*0.4*8) + 2*(40*8*0.4*8)] d. Aspect Ratio Aspect ratio relates the length of an ESP to its height and is an important factor in reducing rapping loss (dust re-entrainment). Aspect ratios for ESPs range from 0.5 to 2.0. However, for high-efficiency ESPs (those having collection efficiencies of > 99%), the aspect ratio should be greater than 1.0 (usually 1.0 to 1.5). For Recovery 1, Length of each plate = 0.4 m No. of plates in each field =8 Thus, total length of plates in each field = 3.2 m No. of fields =3 Thus, total length of plates = 9.6 m Thus, Effective length = 9.6 m Effective height =8m Thus, AR = 9.6/8 = 1.2 e. Corona Power The corona power is the power that energizes the discharge electrodes and thus creates the strong electric field. A strong electric field is needed for achieving high collection efficiency of dust particles. 68 | P a g e The following values are recorded for Recovery 1 and 2: For Recovery 1, Field 1 2 Peak Voltage Average Voltage Current [mA] (Supplied) [kV] [kV] 65 50 80 65 50 100 Table 9.3. Corona power of ESP of Recovery 1 Corona Power, Pc [kW] 4 5 *The values are taken normal performance; ESP at Recovery 1 is producing less corona power most of the time For Recovery 2, Field 1 2 3 Peak Voltage Average Voltage Current [mA] (Supplied) [kV] [kV] 65 62 53 95.5 83.6 154 55 45 250 Table 9.4. Corona power of ESP of Recovery 2 9.00 kW 27.41 kW Corona Power, Pc [kW] 3.286 12.874 11.250 For Recovery 1, total Pc = For Recovery 2, total Pc = The corona power generated in Recovery 1 and Recovery 2 at normal conditions is close to ideal values. However, as mentioned ESP of Recovery 1 often produces reduced Corona power and thus its performance is adversely affected. f. Dust dislodging system Dust build up on collection plate reduces corona power of the field and sometimes lead to back corona, further reducing electric field strength. With the installment of Alstom controller for rapping, dust dislodging is highly improved. The problem of inefficient performance of ESP and frequent failures of conveyor belt was supposed to be due to rapping problems. 69 | P a g e 9.3. Collection Efficiency Practical Collection Efficiency, = *100 The outlet dust concentration is taken from flue gas analyzer. For inlet dust concentration, an experiment is performed on Ash mixing tank. Experiment: For Recovery 2, density of AMT is noted at different time intervals with ESP ash falling rate as the only variable and rest as constants. Gas flowrates are noted down for different sampling periods. To calculate rate of ash collected in ESP through sampling AMT density. With known gas flowrate practical collection efficiency is calculated. Objective: Procedure: To calculate inlet dust concentration, two parameters can be evaluated – ash collection rate and inlet gas flow rate. The ratio of Ash collection rate to Inlet gas flow rate when added with outlet dust concentration will give Inlet dust concentration. = ℎ + . To calculate ash collection rate AMT density sampling is done. The outlet flow to MDT from AMT was closed and the level in the tank is made to rise to 65% as displayed on DCS. WWL and hot water inlet supply is then closed to maintain the volume constant during sampling period. Density of AMT sample was taken at an interval of 15 minutes. The solids fired in the boiler remained constant during the experiment. The soot blowing was switched off to prevent ash from superheaters, boiler bank and economizer from falling into the tank. The system is assumed to be in steady state with no excess ash falling and no ash building on collection plate. Multiple samples are taken to determine average ash collection rate as there is variability in ash falling rate depending upon rapper frequency. We assume that all the ash falling is collected and is falling from ESP only during the experiment. Constants during the experiment are time interval, tank level, MDT outlet flow = 0, Hot water inlet flow = 0, WWL inlet flow = 0, firing rate, % solids in BL, soot blower = off. Variables during the experiment are Gas flow rate and ESP ash quantity. 70 | P a g e Gas flowrates and their temperatures are taken are taken from DCS. Collection efficiency is calculated after processing these values in appropriate units. Observation table and Results: Thus, Tank Volume = 10 m3 Tank Level = 63.5 % Volume of tank filled = 6.35 m3 ρ 0.75 (kg/m3) Temp 200 (°C) Pressure = 1 bar 0.8 160 1.2 30 Firing rate = 26 TPH Solids firing rate = 17.5 TPH Amount of water = 8.5 TPH Vapor generation rate = 3.11 (m3/s) Symbol Sample Time Temp. at density Twaddell calculation Weight Unit Formula 1 2 3 4 5 1445 1500 1515 1530 1545 39 40 41 40 40 15 16 17 18 19 53.138 53.29 53.558 53.724 54.01 50 50 50 50 50 1062.76 1065.8 1071.16 1074.48 1080.2 Hours °C g Density A ∆ρ B ESP Ash collected (/15 min) kg A*6.35 Volume ml Ρ kg/m3 kg/m3 3.04 5.36 3.32 5.72 19.304 34.036 21.082 36.322 71 | P a g e Symbol D2 D3 D4 D7 D8 D9 D1 D10 Net Sample Temp °C Time Unit Flow rate TPH Nm3/s D1+D2+D3 14.66474 14.66474 14.31385 13.96295 13.96295 Formula 34 34 33 32 32 159 159 159 160 159 1 2 3 4 5 Primary Flow Flow Temp Normal FR rate rate Hours TPH °C m3/s Nm3/s D1*10 / D2*293/468 (36*0.75) 1445 23 195 8.518519 5.3331751 1500 23 197 8.518519 5.3331751 1515 22.5 196 8.333333 5.2172365 1530 22 197 8.148148 5.1012979 1545 22 196 8.148148 5.1012979 D5 D6 Gas Flow Rate Secondary Flow Normal FR rate m3/s Nm3/s D4*10 / D5*293/468 (36*0.75) 11.80556 7.98851681 11.80556 7.98851681 11.45833 7.75356043 11.11111 7.51860405 11.11111 7.51860405 Tertiary Flow Flow Temp Normal FR rate rate TPH °C m3/s Nm3/s D7*10 / D8*293/468 (36*0.75) 6 30 1.388889 1.34305097 6 30 1.388889 1.34305097 6 30 1.388889 1.34305097 6 30 1.388889 1.34305097 6 30 1.388889 1.34305097 Symbol Time E Flow to ESP Inlet Sample F G H I Inlet Dust Inlet Dust Outlet Dust Net Inlet Dust Concentration Concentration Concentration Concentration Average g/Nm3 F average mg/Nm3 g/Nm3 G+H Collection Efficiency Unit Hours D10+3.11 Nm3/s g/Nm3 [B*1000 / (15*60)] / E Formula (G/I)*100 1 2 3 4 5 15.6389098 28.12917122 17.78138801 30.63540343 1445 1500 1515 1530 1545 17.77474 17.77474 17.42385 17.07295 17.07295 23.046 120 23.166 99.482 72 | P a g e Conclusion: The collection efficiency is close to designed value of 99.53. But to meet environmental norms outlet dust concentration, must be 75 mg/Nm3. Thus, required CE = 99.676. When the amount of liquor burned is increased to 27 TPH or 28 TPH, it is believed that outlet dust concentration increases significantly. Thus, it can be deduced that maximum capable load of ESP is reached at firing rate of 26 TPH. It can be concluded that maximum collection efficiency of ESP is 99.50, under these conditions. To get 75 mg/Nm3 outlet dust concentration inlet dust concentration should be 15 g/Nm3. Thus, either process conditions can be varied like moisture or dust composition or inlet dust load can be reduced to reduce outlet dust concentration. A multi-cyclone or other mechanical dust collector is used to reduce the inlet dust load. Specific Collection Area calculation: Total collection area = Gas flow rate = Inlet temperature = Outlet temperature = Gas flow rate (@170 °C) = Thus, For SCA = 1000 m3/hr, CA = 3276.8 m2 17.424 Nm3/s 180 °C 160 °C 26.344 m3/s 124.38 m2/m3s-1 34.55 m2 For 99.5 % above efficiencies conservative SCA is 20-25 m2 for 1000 m3/hr. The SCA in operation is sufficiently above the ideal value. Experiment 9.1. Calculation of Practical Collection Efficiency A standard of outlet dust concentration equal to 75 mg/Nm3 in ESPs of both the units is targeted. Figure 9.2. Dust collection systems 9.4. DUST COMPOSITION To understand dust characteristics, dust composition is very important. Quantity Moisture Loss on Ignition Carbonates as Na2CO3 Sulfates as Na2SO4 Chlorides as NaCl Acid insoluble Water insoluble Unit % by weight % by weight % by weight % by weight % by weight % by weight % by weight Value 0.31 24.8 28 27.9 33.1 0.42 15.85 18.86 20.09 As Base Group 0.19 Table 9.5. ESP dust composition Elemental analysis of ESP is also done to determine the amount of Na and K in the ash. Experiment: Objective: Elemental analysis of ESP ash to determine Na and K To determine % of Na and K in ESP ash Observation table and Results: Sample 1 2 Wt of sol. (g) 10002 6251.88 PPM Na 39.8 76.3 Wt in g Na 0.398 0.477 % Wt K 0.678 0.68 23.044 - Na 35.765 – K K 67.8 108.8 Conclusion: Based on above data and various journals, articles and discussions, the final composition of ESP ash is concluded to be: 74 | P a g e Quantity Na2SO4 K2SO4 NaCl KCl Na2CO3 K2CO3 Units mole mole mole mole mole mole Value 0.098 0.098 0.283 0.283 0.198 0.066 The presence of K and Cl expressed as ratios: Chloride Enrichment Factor (CEF), Cl/(Na + K) mole % = 29.525 For wood based paper plants, the general CEF value is 1.5-2.5 %. Potassium Enrichment Factor, (PEF), K/(K + Na) mole % = 47.835 For wood based paper plants, the general PEF value is 1.2-2 %. Experiment 9.2. ESP Dust elemental analysis To increase the collection efficiency of ESP, treating K and Cl can help. 9.5. POTASSIUM & CHLORIDES PURGING The chloride and potassium content in the ESP dust are very large. The presence of these elements adversely affects ESP and Recovery Boiler. High content of Chlorides and Potassium causes corrosion, cracking and fouling in Recovery boilers and causes ESP problems in form of inlet corona suppression and build ups on the ESP internals. Also, it is important to note that at low chloride concentrations, potassium has very little effect on sticky deposit temperature. On the other hand, when the chloride mole % [Cl/(Na+K)] exceeds 10%, potassium has a significant effect on lowering the sticky temperature.9 Figure 9.3. Effect of Chloride and Potassium on Sticky Deposit Temperature (TSTK) 9 Moyer S., Wiggins D., Blair M.A. and Hiner L.A. (2000). Liquor Cycle Chloride Control Restores Recovery Boiler Availability 75 | P a g e The sticky temperature is the temperature that results in a sticky deposit with 15% liquid phase (TSTK). Of the various sources of potassium and chlorides in the system the important ones are10: a. Bound to wheat straw or wood b. Makeup caustic c. Make up lime d. Fresh water The 2 major points that can be interfered for reduction of potassium and chlorides are: a. Wet washing By adapting to rigorous wet washing and using hot water with minimum reuse of water, potassium and chloride content can be reduced. Potassium and chlorides easily dissolve in water and can be removed at the potential source. b. Purging precipitator dust The potassium and chlorine content is highest in precipitator dust. Thus purging precipitator dust and treating it is one important method of potassium and chlorides removal. Various methods for potassium and chlorides removal through precipitator dust purging are: a. Ash Purging By purging some amount of ESP ash highly concentrated with potassium and chlorides, a proper balance can be maintained. It is practiced at Alabama River Pulp and Alabama Pine Pulp of 1200 and 1600 TPD capacity. It has disadvantage that alkali is also lost with ash and needs to be covered by makeup caustic. b. Ash leaching It is the most popular method where ash and water are mixed in a slurry. Most of the alkali remains solid while most of the potassium and chlorine dissolve. By centrifuge liquid fraction is separated from solid fraction, where liquid fraction is sent to waste water treatment and alkali is returned to liquor cycle. c. Electrodialysis using a bipolar membrane d. Specific crystallization processes Sodium sulfate and carbonate crystals are selectively removed from a concentrated filtrate stream containing potassium and chlorine. It is used in Champion International Corporation’s bleach filtrate recycle process in Canton, North Carolina. Systems based on Ash Leaching: a. AshLeach [Metso Power] b. ARC [Andritz] CEF in the range of 1.5 – 2.5 % and PEF in the range of 1.2 – 2 % are targeted. Michael A., Craig J., A. Mark and Douglas W. An overview of various strategies for balancing saltcake, chloride and potassium levels in an ECF kraft mill 10 76 | P a g e 9.6. ESP ORE LOSS For Recovery 2 Outlet gas concentration = 120 mg/Nm3 Gas Flow Rate = 17.424 Nm3/s Thus, Outlet SPM flow rate = 2.091 g/s or 0.181 MT/day % Weight of Na as Na2O = 31.06 Thus, Outlet Na flow rate = 0.0561 MT of Na as Na2O/day Thus, Outlet Na flow rate = 10.83 MT of Na as Na2O/day Inlet dust concentration = 23.166 g/Nm3 With ESP shutdown, Outlet SPM flow rate = 403.64 g/s Outlet Na flow rate (considering 2 hour ESP shut down) = 0.954 MT of Na as Na2O/day For Recovery 1 Inlet dust concentration = 23 g/Nm3 (Considering similar performance as Recovery 2 boiler) With 80% collection efficiency, outlet dust concentration = 4.6 g/Nm3 Gas flow rate = 5.5 Nm3/s Thus, Outlet SPM flow rate = 25.3 g/s or 2.186 MT/day Thus, Outlet Na flow rate = 0.6789 MT of Na as Na2O/day Data table 9.6 in Appendix A The soda loss in Recovery 2 through Flue gas carryover of total soda losses is 11.48 %. The corresponding loss in ORE in Recovery 2 through Flue gas carryover is 0.817 %. The soda loss in ORE in Recovery 1 through Flue gas carryover is 8.15 %. The corresponding loss in ORE in Recovery 1 through Flue gas carryover is 0.580 %. The combined soda loss in ORE in Recovery 1 and Recovery 2 through Flue gas carryover is 19.63 %. The corresponding loss in ORE in Recovery 1 and Recovery 2 through Flue gas carryover is 1.397 % A standard of 75 mg/Nm3 of outlet dust concentration is targeted for Recovery 1 and Recovery 2. Also identified performance parameters must be in desired range. 77 | P a g e 10. ORE LOSS DATA Mud Filter, Grifts and Stones % Loss of Total soda loss % Loss in ORE Flue gas carryover [ESP] Soda Carryover with Pulp Screen Losses in Pulp mill Total 7.50 0.712 19.63 1.397 69.59 5.108 2.81 0.201 99.53 7.418 Table 10.2. % Loss from significant loss points 99.53 % of the total soda losses are explained by these 4 major loss points. Steps to reduce soda losses from these points and set targets are discussed in the report before. % Loss (ORE) Recovery I & II Mud Filter Grifts and Stones Dregs Washer Flue gas carryov er [ESP] Condenser, Vibro Screen, & MDT Outlet Seepage & Overflow SFL and WFL Soda Carryover with Pulp Screen Losses in Pulp mill Seepage & Overflow Date 01-Jun 17-Jun 0.677 0.035 0 1.397 0.05 0 5.108 0.201 0 Table 10.3. % Net Loss in ORE from individual loss points ORE based on individual losses is 92.532 %. Data table 10.1 in Appendix A The average ORE based on stock (June 1st – June 17th 2010) is 94.000 %. If the suggestions are implemented and standards are met, ORE can be increased to 97-97.5 %. While the ORE from stock has come out to be 94 %, in general the ORE on average basis is approximately 94.5 %. However ORE based on individual losses has come significantly higher than that based on stock. The reason of difference in ORE based on stock and ORE based on individual losses could be: a. Screen losses are calculated based on limited number of sampling and could be lower than estimated. b. Due to very high soda carryover through pulp in WFL, ORE could have been affected. 78 | P a g e 11. FUTURE WORK a. A rigorous study can be done by quantifying loss data from every possible major soda loss source. b. WBL sampling should be done for few weeks and results should be analyzed. c. Quotations for online analyzers can be invited from suppliers and the economic viability of the change can be analyzed. d. Samples should be analyzed while displacement washing for weeks and results should be tabulated to see any benefits. e. Mud cake sampling can be done with Filter Aids and benefits can be noted. f. Causticizing control models can be studied for better lime control. g. Proper steps should be taken to reduce soda loss in pulp carryover. h. % Charging (White liquor charged per tonne of fibres cooked in the digester) could be plotted against the soda carryover as kg/MT and production. A relative study can be done whether higher production has resulted in increased charging and thus, increased soda loss. i. Pulp mill reject should be treated with hot water and moisture should be reduced. Samples should be analyzed to observe any benefits. j. ESP process parameters like resistivity and theoretical collection efficiency should be evaluated through an external lab for better understanding of performance limitations. k. The amount of Potassium and Chlorine needs to be reduced through proper steps. In brief, First, Check Technical and Economic viability for a. Composite sampling or Automation in WBL testing b. Automation in lime slaking c. Filter Aid use in Mud filter d. Pulp mill reject washing e. Potassium and Chlorides purging With the proposed benefits if technical and economical viability is found then, Perform rigorous sampling for a month to validate observations in a. WBL TTA b. Mud cake displacement washing c. ESP collection efficiency d. ESP Dust composition 79 | P a g e 12. REFERENCES Dalmon J. (1980). Electrostatic precipitators for large power station boile, Dalmon J. and Tidy D. (1972). A comparison of chemical additives as aids to the electrostatic precipitation of fly ash Johnson M. (1996). The effect of humidity on the performance of electrostatic precipitators at Tarong Power Station Harker J.R. and Pimkarkar P.M. (1988). The effect of additives on the electrostatic precipitation of flu ash Tran H.N. Kraft Recovery Boiler Plugging and Prevention Jaye P. H. History of Alabama River Pulp Company and The Claiborne Mill Complex Unified Air Toxics, (August 2000). www.epa.gov/ttn/uatw/pulp/pulppg.html Moyer S., Wiggins D., Blair M.A. and Hiner L.A. (2000). Liquor Cycle Chloride Control Restores Recovery Boiler Availability Mckean W. and Jacobs R. S. (1997). Wheat Straw as a Paper Fiber Source M. Brongers, A. J. Mierzwa. Pulp and Paper American Forest & Paper Association (AF&PA). (October 1999). www.afandpa.com Michael A., Craig J., A. Mark and Douglas W. An overview of various strategies for balancing saltcake, chloride and potassium levels in an ECF kraft mill Uschan R.M. and Trick L.C. (Sept. 1994). Corrosion Control Needs of the Pulp and Paper Industry Rose, H. E., and A. J. Wood. An Introduction to Electrostatic Precipitation in Theory and Practice U.S. EPA 1985 Pirita Mikkanen. Fly ash particle formation in Kraft Boilers Hein A.G and Gibson D. Skewed Gas Flow Technology Improves Precipitator Performance Prakash H. Dhargalkar, Jose Astolphi, Jr. Advancements in air pollution control for pulp and paper Industry Ibach, S. Conversion to high solids firing Kraft Recovery Boilers, TAPPI Press ESP Design Parameters and Their Effects on Collection Efficiency, Lesson 3 Gallaer C. A. (1983). Electrostatic Precipitator Reference Manual. Electric Power Research Institute Coal and Ash Testing and Predictive Analyses, Neundorfer, Inc. Chandra A., Sanjeev Kumar, Subodh Kumar and Sharma P.K. Investigations on Fly Ash Resistivity: Development of Empirical Relations Based on Experimental Measurement Thomas e. Sulpizio. Advances in filter aid and precoat Filtration technology. Presentation at the American filtration & separations society Rees, R. H. and Cain, C. W. (1990). Let Diatomite Enhance Your Filtration Environmental, Health, and Safety Guidelines Pulp and Paper Mills Arpalahti.O., White liquor preparation, Paper Making Science and Technology 80 | P a g e LIST OF EXPERIMENTS Experiment 4.1. FMEA on identified exit points of soda for permanent losses [Page 27] Experiment 5.1. Frequent sampling of WBL from SFL and WFL [Page 32] Experiment 6.1. Mud cake sampling from Mud filter of Recovery 2 [Page 42] Experiment 6.2. Vat and Mud sampling to test homogeneity from Mud filter of Recovery 2 [Page 43] Experiment 6.3. Displacement washing in mud filter of Recovery 2 [Page 46] Experiment 7.1. Analysis of total washable alkali in washed pulp in WFL [Page 55] Experiment 8.1. Reject stream analysis for TTA in WFL and SFL [Page 56] Experiment 8.2. Analysis of total washable alkali in pulp from reject stream in WFL and SFL [Page 57] Experiment 9.1. Calculation of Practical Collection Efficiency [Page 70] Experiment 9.2. ESP Dust elemental analysis [Page 74] LIST OF TABLES Table 5.1. PME, SRE and ORE over Time [Page 31] Table 6.1. Loss through Mud filter for Recovery 1 and 2 [Page 84] Table 6.2. Loss through Mud filter for Recovery 1 and 2 combined [Page 85] Table 6.3. Loss through Grifts and stones for Recovery 1 and 2 [Page 86] Table 6.4. Combined loss through Mud filter and Grifts and stones for Recovery 1 and 2 [Page 87] Table 7.1. Soda carryover with pulp in SFL [Page 88] Table 7.2. Soda carryover with pulp in WFL [Page 90] Table 7.3. Combined soda carryover with pulp in SFL and WFL [Page 92] Table 7.4. WFL production and total soda loss [Page 94] Table 7.5. SFL production and total soda loss [Page 98] Table 8.1. Soda loss from Screens as Reject in WFL and SFL [Page 101] Table 8.2. Combined soda loss from Screens as Reject in WFL and SFL [Page 104] Table 9.1. BHEL ESP Design Conditions [Page 64] Table 9.2. ESP characteristics with Resistivity [Page 67] Table 9.3. Corona power of ESP of Recovery 1 [Page 69] Table 9.4. Corona power of ESP of Recovery 2 [Page 69] Table 9.5. ESP dust composition [Page 75] Table 9.6. ESP ORE Loss [Page 106] Table 10.1. Average ORE based on stock [Page 108] Table 10.2. % Loss from significant loss points [Page 31] Table 10.3. %Loss in ORE from individual loss points [Page 31] 81 | P a g e LIST OF FIGURES Figure 1. Sulfuric Acid Plant (SAP) at Abhishek Industries, Dhaula complex [Page 9] Figure 2. COGEN-1, a 20 MW unit at Abhishek Industries, Dhaula complex [Page 9] Figure 3. Demineralised water plant at Abhishek Industries at Dhaula complex [Page 10] Figure 1.1. Paper making process [Page 11] Figure 1.2. Paper making flowchart [Page 12] Figure 1.3. Chemical Recovery Cycle [Page 13] Figure 1.4. Multiple effect evaporators [Page 13] Figure 1.5. Recovery Boiler Process flow [Page 14] Figure 1.6. Recovery Boiler [Page 14] Figure 1.7. Recausticizing Process flow [Page 15] Figure 4.1. Process Flow Diagram of Recovery 2 [Page 18] Figure 4.2. Evaporator Process Flow Diagram [Page 19] Figure 4.3. 7 effect/11 body Evap. at Recovery2 at Abhishek Industries, Dhaula complex [Page 19] Figure 4.4. Condensers at Recovery 2 at Abhishek Industries, Dhaula complex [Page 20] Figure 4.5. Recovery Boiler Process Flow Diagram [Page 20] Figure 4.6. Rotary lime kiln [Page 21] Figure 4.7. Recausticizing Process Flow Diagram [Page 23] Figure 4.8. Wet Washing in SFL [Page 24] Figure 4.9. Digester in SFL [Page 24] Figure 4.10. Pulp washing in SFL [Page 25] Figure 4.11. Digester Feed Belt in SFL at Abhishek Industries, Dhuala complex [Page 26] Figure 5.1. PME versus Time plot [Page 31] Figure 5.2. SRE versus Time plot [Page 31] Figure 5.3. ORE versus Time plot [Page 31] Figure 5.4. Proposed collection tank design for WBL composite sampling [Page 37] Figure 6.1. Lime mud filter flowsheet [Page 39] Figure 6.2. Vacuum disk filter sketch [Page 39] Figure 6.3. Vacuum disk filter in operation [Page 39] Figure 7.1. Production versus Time in WFL [Page 50] Figure 7.2. Soda carryover as kg/MT of unbleached pulp versus Time in WFL [Page 50] Figure 7.3. Production and Soda carryover versus Time in WFL [Page 51] Figure 7.4. Soda carryover versus Production in WFL [Page 51] Figure 7.5. Production versus Time in SFL [Page 52] 82 | P a g e Figure 7.6. Soda carryover as kg/MT of unbleached pulp versus Time in SFL [Page 52] Figure 7.6. Production and Soda carryover versus Time in SFL [Page 53] Figure 7.8. Soda carryover versus Production in SFL [Page 53] Figure 7.9. Brown Stock Washer [Page 54] Figure 8.1. HD Cleaner, Delta Knotter and Vibratory Screen in SFL [Page 59] Figure 8.2. HD cleaner [Page 60] Figure 8.3. Delta Knotter [Page 60] Figure 8.4. Vibratory Screen [Page 60] Figure 8.5. Delta Screen, Opti Screen, Centricleaner and Vibratory Screen in SFL [Page 60] Figure 8.6. Vibratory Screen in WFL [Page 61] Figure 8.7. Centricleaner [Page 61] Figure 8.8. Delta Screen [Page 61] Figure 8.9. Pressure Screen [Page 61] Figure 8.10. Pressure Screen, Centricleaner and Vibratory Screen in WFL [Page 61] Figure 8.11. Hot water header for washing [Page 62] Figure 9.1. ESP [Page 63] Figure 9.2. Dust collection systems [Page 74] Figure 9.3. Effect of Chloride and Potassium on Sticky Deposit Temperature (TSTK) [Page 75] 83 | P a g e APPENDIX A Table 6.1. Loss through Mud filter for Recovery 1 and 2 Loss through Mud Filter Recovery I CaCO3 Producti on (MT) CaCO3 Production (MT) Recovery II % Soda (TTA Na2O) Date Shift Total Loss (MT) 1.489 13.641 10.123 4.394 17.856 22.419 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun C A B C A B C A B C A B C A B C A B C A B 22.625 WL Consumed (TTA Na2O MT) 46.83205 48.4345 37.6221 44.39643 46.4072 38.4144 35.28467 38.22762 42.49794 39.73044 30.30216 27.8812 40.97628 40.44386 41.22212 44.54126 41.74747 49.50078 45.65228 40.76672 41.49194 19.10005 19.12522 19.12522 20.02093 15.64791 19.12522 17.4095 19.20112 19.17575 19.15045 17.85714 19.17575 17.4095 19.12522 19.12522 19.15045 19.15045 20.8914 19.17575 17.4095 19.15045 49.07032 45.50486 45.50486 47.31781 47.25504 47.25504 50.75542 40.36136 40.36136 54.32785 38.50411 38.65793 40.36136 26.2528 7.019368 50.82283 49.07032 52.57534 50.75542 43.75467 42.00448 Lime consum ption (MT) 11 11 11 11.5 9 11 10 11 11 11 10 11 10 11 11 11 11 12 11 10 11 % Ca(OH)2 in Mud Cake 2.1 2 2 1.9 2 2 1.9 1.7 1.8 1.9 0 1.8 1.9 2 2 1.9 1.9 1.9 1.8 1.9 1.9 Total % Soda Soda loss (TTA (Na2O Na2O) MT) 0.44 0.0840402 0.45 0.0860635 0.45 0.0860635 0.45 0.0900942 0.5 0.0782395 0.46 0.087976 0.45 0.0783428 0.45 0.086405 0.45 0.0862909 0.45 0.086177 0 0 0.43 0.0824557 0.44 0.0766018 0.46 0.087976 0.46 0.087976 0.45 0.086177 0.46 0.0880921 0.45 0.0940113 0.44 0.0843733 0.45 0.0783428 0.45 0.086177 Lime consum ption (MT) 28 26 26 27 27 27 29 23 23 31 22 22 23 15 4 29 28 30 29 25 24 % Ca(OH)2 in Mud Cake 1.4 1.5 1.5 1.4 1.5 1.5 1.5 1.3 1.3 1.4 1.5 1.2 1.3 1.5 1.3 1.4 1.4 1.4 1.5 1.5 1.5 0.48 0.46 0.45 0.46 0.45 0.44 0.45 0.44 0.46 0.46 0.44 0.43 0.44 0.45 0.45 0.44 0.45 0.46 0.46 0.45 0.45 Total Soda loss (Na2O MT) 0.2355375 0.2093223 0.2047719 0.2176619 0.2126477 0.2079222 0.2283994 0.17759 0.1856623 0.2499081 0.1694181 0.1662291 0.17759 0.1181376 0.0315872 0.2236204 0.2208164 0.2418466 0.2334749 0.196896 0.1890202 Table 6.2. Loss through Mud filter for Recovery 1 and 2 combined Loss through Mud Filter Combined Total Loss (MT) % Loss (ORE) 1.489 0.905799 60.83270334 Total Soda loss (Na2O MT) % Loss through Mud filter of Total loss General Loss % (%) Avg % Loss (ORE) Date Shift 13.641 0.8945415 6.557741653 10.123 0.8426904 8.324512127 4.394 0.7541881 17.16404402 7.232 0.677 17.856 0.5798686 3.247472103 22.419 0.9545639 4.257834314 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 22.625 0.8682842 3.837720434 C A B C A B C A B C A B C A B C A B C A B WL Consumed (TTA Na2O MT) 46.83205 48.4345 37.6221 44.39643 46.4072 38.4144 35.28467 38.22762 42.49794 39.73044 30.30216 27.8812 40.97628 40.44386 41.22212 44.54126 41.74747 49.50078 45.65228 40.76672 41.49194 0.682391 0.609867 0.773044 0.6932 0.626815 0.770279 0.869335 0.690587 0.639921 0.845913 0.559096 0.891945 0.620339 0.509629 0.290046 0.695529 0.739945 0.67849 0.696237 0.675156 0.663255 85 | P a g e Table 6.3. Loss through Grifts and stones for Recovery 1 and 2 Grifts and Stones Recovery I Total Loss (MT CaCO3) % Soda (TTA Na2O) 0.5 0.0125 6 0.5 0.03 0.0425 % Soda (TTA Na2O) General Loss % (%) 2.5 Total Soda loss (Na2O) Total Loss (MT CaCO3) Total Soda loss (Na2O) Total Soda loss (Na2O) Recovery II Combined % Loss (ORE) Avg % Loss (ORE) 0.032 Date Shift Total Loss (MT) 1.489 13.641 2.5 0.5 0.0125 6 0.5 0.03 0.0425 0.033 10.123 2.5 0.5 0.0125 6 0.5 0.03 0.0425 0.037 4.394 2.5 0.5 0.0125 6 0.5 0.03 0.0425 0.269 0.043 0.035 17.856 2.5 0.5 0.0125 6 0.5 0.03 0.0425 0.035 22.419 2.5 0.5 0.0125 6 0.5 0.03 0.0425 0.031 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 2.5 0.5 0.0125 6 0.5 0.03 0.0425 C A B C A B C A B C A B C A B C A B C A B 22.625 WL Consumed (TTA Na2O MT) 46.83205 48.4345 37.6221 44.39643 46.4072 38.4144 35.28467 38.22762 42.49794 39.73044 30.30216 27.8812 40.97628 40.44386 41.22212 44.54126 41.74747 49.50078 45.65228 40.76672 41.49194 0.033 86 | P a g e Table 6.4. Combined loss through Mud filter and Grifts and stones for Recovery 1 and 2 Mud Filter and Grifts Combined Date Shift Total Loss (MT) General Loss % (%) 1.489 Avg % Loss (ORE) 13.641 10.123 4.394 7.501 0.712 17.856 22.419 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 22.625 C A B C A B C A B C A B C A B C A B C A B WL Consumed (TTA Na2O MT) 46.83205 48.4345 37.6221 44.39643 46.4072 38.4144 35.28467 38.22762 42.49794 39.73044 30.30216 27.8812 40.97628 40.44386 41.22212 44.54126 41.74747 49.50078 45.65228 40.76672 41.49194 87 | P a g e Table 7.1. Soda carryover with pulp in SFL Soda Carryover SFL Date Shift Total Loss (MT) % Soda (TTA Na2O, Kg/MT) Pulp Production (MT) Soda Loss (MT) Total Soda Loss (MT) % Loss in Soda Carryover WL Consumed (TTA Na2O MT) % Loss (SFL PME) % General Loss (Total Loss) Avg % Loss (SFL PME) 36.75 3.766081 252.92685 4.975 1.489 13.641 3.554537 26.057747 10.123 2.893575 28.584164 4.394 2.500159 56.899389 36.75 4.975 17.856 3.535516 19.800156 22.419 3.722962 16.606282 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 86 88.88 84.58 81.9 83.51 86.67 74.47 80.47 88.41 84.07 53.11 61.43 87.88 89.12 86.1 86.67 86.99 87.63 85.69 90.27 79.34 3.46285 15.305415 1.250392 1.237936 1.277754 1.176476 1.257943 1.120118 0.923428 0.924045 1.046102 1.075504 0.630737 0.793918 1.14343 1.144 1.248086 1.290406 1.154639 1.277917 1.092487 1.237589 1.132774 24.98705 26.1545 21.1951 27.47343 24.6942 22.0274 18.66867 21.32362 25.78394 22.63644 13.41116 16.7262 24.22728 23.63286 24.60912 28.35826 24.55047 27.35278 23.20928 24.21172 24.62994 C A B C A B C A B C A B C A B C A B C A B 22.625 14.5394366 13.928169 15.1070423 14.3647887 15.0633803 12.9239437 12.4 11.4830986 11.8323944 12.7929577 11.8760563 12.9239437 13.0112676 12.8366197 14.4957746 14.8887324 13.2732394 14.5830986 12.7492958 13.7098592 14.2774648 5.0041584 4.7331651 6.0285332 4.2822327 5.0940824 5.0851131 4.9464049 4.3334337 4.0571844 4.7512063 4.7030783 4.7465525 4.7195979 4.8407156 5.0716409 4.5503724 4.7031242 4.6719819 4.7071135 5.1115286 4.5991751 88 | P a g e 2.468 3.078792 124.74846 -6.834 3.594019 -52.59027 -9.661 3.18591 -32.97702 1.108 1.635419 147.60103 3.38 2.465111 72.932286 16.98 3.148556 18.542735 -2.08 2.917103 -140.2454 6.93 3.302852 47.660199 11.62 3.363751 28.94794 08-Jun 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 3.770259 72.925712 C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.17 14.5394366 12.9239437 12.7492958 14.3647887 14.7140845 13.4478873 12.4873239 12.8366197 14.4521127 11.7014085 14.5830986 0 12.1380282 13.4478873 15.0197183 15.456338 12.8802817 12.1380282 13.1859155 13.1859155 13.0112676 12.5746479 12.3126761 12.1816901 13.971831 12.7492958 11.9197183 15.1070423 12.8366197 11.6577465 72.83 78.92 78.43 80.92 83.67 89.27 86.2 83.6 71.71 71.33 54.91 0 20.14 80.18 76.06 90.51 79.84 59.42 81.11 55.84 85.41 90.58 89.33 87.34 89.13 88.88 82.66 96.57 94.53 94.18 1.058907 1.019958 0.999927 1.162399 1.231127 1.200493 1.076407 1.073141 1.036361 0.834661 0.800758 0 0.24446 1.078252 1.1424 1.398953 1.028362 0.721242 1.06951 0.736302 1.111292 1.139012 1.099891 1.063949 1.245309 1.133157 0.985284 1.458887 1.213446 1.097927 19.581 20.15745 23.19216 24.9565 21.44608 24.28979 23.60832 26.16104 16.74419 22.67496 3.834 0 12.61416 23.46552 22.0563 23.2686 19.43172 19.52412 19.67256 19.15182 24.88068 25.8447 26.99169 21.5016 23.2848 24.98796 23.3709 26.8422 25.43688 20.92122 5.4078299 5.0599537 4.3114883 4.6576992 5.740571 4.9423766 4.5594406 4.1020594 6.1893767 3.6809832 20.885705 0 1.9379799 4.5950467 5.1794715 6.0121931 5.2921805 3.6941057 5.4365553 3.8445512 4.4664871 4.407138 4.0749258 4.9482309 5.348164 4.5348136 4.2158578 5.4350503 4.7704186 5.2479089 89 | P a g e Table 7.2. Soda carryover with pulp in WFL Soda Carryover WFL Date Shift Total Loss (MT) % Loss (SFL PME) % Soda (TTA Na2O, Kg/MT) Pulp Production (MT) Soda Loss (MT) Total Soda Loss (MT) % Loss in Soda Carryover % General Loss (Total Loss) WL Consumed (TTA Na2O MT) Avg % Loss (SFL PME) 32.84 3.298064 221.49521 5.427 1.489 13.641 2.892856 21.207067 10.123 2.475641 24.455608 4.394 2.486506 56.588675 32.84 5.427 17.856 2.872252 16.085641 22.419 2.977925 13.283041 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 08-Jun 3.207578 14.177142 2.463371 99.812433 49.267 51.179 36.246 32.698 52.187 38.88 40.081 34.207 34.687 38.203 40.124 24.549 36.533 49.341 38.456 36.862 37.187 51.089 39.559 38.91 50.768 22.059 1.1788 1.253597 0.865667 0.712402 1.221323 0.959131 0.899508 0.788592 0.787541 0.989135 0.924999 0.572372 0.803932 1.178416 0.889904 0.90613 0.878399 1.193396 1.039789 0.953076 1.214714 0.504685 21.845 22.28 16.427 16.923 21.713 16.387 16.616 16.904 16.714 17.094 16.891 11.155 16.749 16.811 16.613 16.183 17.197 22.148 22.443 16.555 16.862 11.354 C A B C A B C A B C A B C A B C A B C A B C 22.625 2.468 23.9267606 24.4943662 23.8830986 21.7873239 23.4028169 24.6690141 22.4422535 23.0535211 22.7042254 25.8915493 23.0535211 23.315493 22.0056338 23.8830986 23.1408451 24.5816901 23.6211268 23.3591549 26.284507 24.4943662 23.9267606 22.8788732 5.3961992 5.6265582 5.2697802 4.2096668 5.624846 5.853001 5.4135048 4.6651195 4.7118671 5.7864447 5.4762861 5.1310806 4.7998795 7.009791 5.3566745 5.5992725 5.1078609 5.3882782 4.6330206 5.7570268 7.2038535 4.4449979 90 | P a g e -6.834 3.042044 44.513382 34.898753 240.7899 -9.661 3.371569 1.108 2.667952 3.38 2.745697 81.233626 16.98 2.01311 11.855772 -2.08 3.204601 154.06737 6.93 3.111317 44.896354 11.62 2.813581 24.213263 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 2.753342 53.256133 A B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.17 23.3591549 25.8042254 25.4112676 23.315493 23.6647887 24.5816901 24.0577465 24.8 24.9746479 22.3985915 25.4985915 23.6647887 23.0535211 20.9140845 23.1408451 25.6732394 22.7478873 24.1450704 25.4112676 22.6605634 20.171831 25.2366197 23.4028169 22.5295775 21.3507042 19.3859155 21.5690141 22.1802817 23.7084507 39.506 40.143 39.676 48.294 38.362 36.853 50.46 50.472 32.742 51.613 27.224 49.726 36.711 34.552 23.531 20.934 40.933 54.331 36.456 42.646 46.767 51.021 37.617 44.16 50.648 38.033 24.756 46.786 49.841 0.922827 1.035859 1.008217 1.125998 0.907829 0.905909 1.213954 1.251706 0.81772 1.156059 0.694174 1.176755 0.846318 0.722623 0.544527 0.537444 0.931139 1.311826 0.926393 0.966382 0.943376 1.287598 0.880344 0.994906 1.08137 0.737305 0.533963 1.037727 1.181653 16.886 16.777 16.592 22.103 16.382 21.886 17.08 21.767 17.01 22.177 11.014 16.339 16.862 21.857 11.494 10.73 17.003 16.718 16.433 22.4 21.706 22.049 16.572 21.895 22.266 16.621 19.353 23.439 10.212 5.4650407 6.1742804 6.0765276 5.0943239 5.5416227 4.139217 7.1074584 5.7504737 4.8072894 5.2128715 6.3026481 7.2021255 5.0190832 3.306142 4.7374911 5.008794 5.4763234 7.8467868 5.6373953 4.3142071 4.3461532 5.8397096 5.3122361 4.5439879 4.8565996 4.4359817 2.7590684 4.4273504 11.571219 91 | P a g e Table 7.3. Combined soda carryover with pulp in SFL and WFL Soda Carryover Combined Shift Total Loss (MT) Total Soda Loss (MT) % Loss in Soda Carryover Avg % Loss (ORE) % General Loss % Loss (ORE) Date 69.59 1.489 7.064145 474.42206 5.108 13.641 6.447393 47.264814 10.123 5.369216 53.039772 4.394 4.986666 113.48806 69.59 17.856 6.407768 35.885798 5.108 22.419 6.700887 29.889323 22.625 2.468 6.670429 29.482557 5.542163 224.5609 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 08-Jun 08-Jun C A B C A B C A B C A B C A B C A B C A B C A 5.19 5.14 5.70 4.25 5.34 5.41 5.17 4.48 4.31 5.20 5.13 4.90 4.75 5.74 5.19 4.93 4.87 4.99 4.67 5.37 5.66 5.05 5.24 92 | P a g e -6.834 6.636064 -97.10365 -9.661 6.557478 -67.87577 1.108 4.303371 388.39093 3.38 5.210808 154.16591 16.98 5.161667 30.398507 -2.08 6.121705 -294.3127 6.93 6.414169 92.556553 11.62 6.177332 53.161203 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 5.17 6.523601 126.18184 B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.09 5.22 5.41 5.18 4.36 5.29 5.94 4.16 7.52 6.30 4.91 4.77 4.25 5.59 5.19 4.52 6.54 4.67 4.39 4.38 4.87 5.11 4.96 4.69 4.31 4.31 4.61 7.32 93 | P a g e Table 7.4. WFL production and total soda loss WFL Period Bleached Pulp (MT) 01-Jan 02-Jan 03-Jan 04-Jan 05-Jan 06-Jan 07-Jan 08-Jan 09-Jan 10-Jan 11-Jan 12-Jan 13-Jan 14-Jan 15-Jan 16-Jan 17-Jan 18-Jan 19-Jan 20-Jan 21-Jan 22-Jan 23-Jan 24-Jan 25-Jan 26-Jan 27-Jan 28-Jan 29-Jan 30-Jan 31-Jan 01-Feb 02-Feb 03-Feb 04-Feb 05-Feb 06-Feb 07-Feb 08-Feb 09-Feb 10-Feb 11-Feb 81.11 85.71 61.59 88.6 94.91 89 98.32 89.61 92.47 95.71 58.43 92.3 98.13 96.14 87.55 97.42 95.67 94.53 97.33 90.21 95.77 92.38 96.56 90.67 80.33 97.85 98.25 90.52 93.43 79.55 97.4 105.27 106.83 105.45 106.24 92.04 105.13 103.18 100.65 96.73 42.99 39.84 Production Weekly Bleached Production 532.956667 Unbleached Pulp (MT) 102.63 99.23 86.44 88.72 87.95 103.89 94.74 97.06 106.75 98.45 76.42 96.79 115.43 102.42 99.28 113.05 98.5 112.23 100.44 109.23 110.11 90.94 94.29 122.05 108.46 91.72 103.17 111.08 119.31 90.39 103.22 107.97 127.9 109.46 120.15 99.57 123.91 121.84 111.63 105.47 28.24 64.06 Soda Loss % Soda Soda Loss (TTA (Weekly Na2O, basis MT) Kg/MT) 10.69718 7.1959951 648.62 10.60986 7.1888162 625.64 11.70141 8.2131016 657.45 14.62676 10.813418 637.33 11.30845 8.2252016 724.14 12.31268 9.9831177 596.93 15.1507 9.778416 12-Feb 13-Feb 14-Feb 15-Feb 16-Feb 17-Feb 18-Feb 19-Feb 20-Feb 21-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb 27-Feb 28-Feb 01-Mar 02-Mar 03-Mar 04-Mar 05-Mar 06-Mar 07-Mar 08-Mar 09-Mar 10-Mar 11-Mar 12-Mar 13-Mar 14-Mar 15-Mar 16-Mar 17-Mar 18-Mar 19-Mar 20-Mar 21-Mar 22-Mar 23-Mar 24-Mar 25-Mar 26-Mar 27-Mar 28-Mar 29-Mar 30-Mar 31-Mar 01-Apr 02-Apr 105.2 105.33 106.19 103.11 92.4 90.01 105.68 106.32 106.75 102.56 83.72 98.37 103.83 94.26 108.73 110.31 109.07 109.48 110.65 92.54 111 109.36 110.59 110.8 108.13 70.74 91.16 107.62 87.57 102.06 98.01 114.4 106.32 112.28 101.94 96.44 112.47 109.18 104.05 109.73 112.95 100.11 108.14 106.21 92.7 95.53 79.76 52.31 98.02 83.34 706.83 708.29 754.42 665.29 753.03 733.89 619.73 107.69 114.13 114.19 116.56 104.67 108.41 107.92 42.64 120.11 94.45 111.02 131.3 112.87 105.23 115.22 113.96 123.19 121.25 116.04 108.33 126.83 128.31 118.77 107.41 110.65 84.59 110.28 121.58 107.8 109.9 118.2 118.61 112.63 118.45 133.76 106.16 115.07 122.02 105.81 121.33 120.9 122.24 112.06 112.61 100.6 115.04 94.62 71.82 74.91 99.6 17.55211 12.194506 22.79155 18.524743 18.9493 15.669931 19.34225 14.758139 18.20704 15.051762 18.42535 14.658289 19.42958 13.468195 95 | P a g e 03-Apr 04-Apr 05-Apr 06-Apr 07-Apr 08-Apr 09-Apr 10-Apr 11-Apr 12-Apr 13-Apr 14-Apr 15-Apr 16-Apr 17-Apr 18-Apr 19-Apr 20-Apr 21-Apr 22-Apr 23-Apr 24-Apr 25-Apr 26-Apr 27-Apr 28-Apr 29-Apr 30-Apr 01-May 02-May 03-May 04-May 05-May 06-May 07-May 08-May 09-May 10-May 11-May 12-May 13-May 14-May 15-May 16-May 17-May 18-May 19-May 20-May 21-May 22-May 100.5 110.27 76.3 110.1 110.02 110.73 110.81 104.47 105.95 90.2 102.45 103.83 84.99 103.18 99.26 98.81 100.04 90.35 99.37 98.04 91.17 77.29 60.62 83.82 96.58 101.17 70.5 96.34 94.98 100.79 100.15 100.49 103.13 103.26 103.67 96 104.66 104.13 105.23 102 112.35 114.04 112.58 112.53 106.11 60.55 104.61 98.5 92.66 108.66 728.38 682.72 616.88 644.18 711.36 762.86 677.4 117.66 119.53 91.28 128.84 106.25 121.03 129.43 121.57 95.32 108.52 114.53 121.37 103.43 94.44 108.28 110.19 109.16 107.38 106.41 108.93 109.3 97.88 65.76 95.34 105.71 111.61 83.49 110.99 97.23 97.39 109.28 110.16 109.58 122.74 106.09 114.87 113.98 119.7 105.92 155.33 113.03 135.51 118.09 121.53 120.6 74.83 115.98 104.95 122.96 108.84 20.7831 16.495961 21.48169 16.342411 23.75211 16.740964 24.97465 17.526209 22.57324 17.758367 19.95352 17.341805 21.39437 16.610158 96 | P a g e 23-May 24-May 25-May 26-May 27-May 28-May 29-May 30-May 31-May 106.31 68.06 86.78 111.82 114.36 74.82 110.89 102.04 110.02 668.77 770.14 128.22 101.92 73.13 103.35 126.26 88.14 130.71 123.98 112.24 23.27183 17.395461 23.5338 18.490038 97 | P a g e Table 7.4. SFL production and total soda loss SFL Period Production Bleached Weekly Unbleached Pulp Bleached Pulp (MT) (MT) Production 01-Jan 02-Jan 03-Jan 04-Jan 05-Jan 06-Jan 07-Jan 08-Jan 09-Jan 10-Jan 11-Jan 12-Jan 13-Jan 14-Jan 15-Jan 16-Jan 17-Jan 18-Jan 19-Jan 20-Jan 21-Jan 22-Jan 23-Jan 24-Jan 25-Jan 26-Jan 27-Jan 28-Jan 29-Jan 30-Jan 31-Jan 01-Feb 02-Feb 03-Feb 04-Feb 05-Feb 06-Feb 07-Feb 08-Feb 09-Feb 10-Feb 11-Feb 210.9 161.76 110.88 190.81 195.73 173.98 124.68 255.84 203.76 219.74 175.76 226.86 198.93 226.01 241.11 150.85 227.13 217.41 234.27 204.78 207.34 225.1 216.96 226.43 135.45 170.71 211.03 200.98 183.38 226.45 240.06 202.779 211.93 198.86 190.08 169.13 179.18 222.06 205.01 205.91 57.1 81.83 1128.26 267.36 218.92 160.11 134.03 198.33 234.3 127.86 268.38 213.35 219.52 165.62 240.51 193.95 244.67 239.17 177.26 208.19 231.07 209.28 232.66 215.89 227.42 219.44 248.21 228.4 206.68 199.6 236.3 189.29 222.03 250.59 237.27 204.82 237.81 196.68 173.78 142.06 226.45 212.54 203.57 96.44 52.83 Weekly Unbleached Pulp (MT) Soda Loss % Soda Soda Loss (TTA (Weekly Na2O, basis MT) Kg/MT) 1508.243333 17.94507 27.065533 1364.54 1395.77 14.88873 20.781246 1446.65 1469.37 17.3338 25.46977 1532.29 1583.97 17.11549 27.110427 1368.06 1532.89 14.80141 22.688931 1374.019 1418.87 15.10704 21.434929 1151.77 1220.48 15.41268 18.810863 98 | P a g e 12-Feb 13-Feb 14-Feb 15-Feb 16-Feb 17-Feb 18-Feb 19-Feb 20-Feb 21-Feb 22-Feb 23-Feb 24-Feb 25-Feb 26-Feb 27-Feb 28-Feb 01-Mar 02-Mar 03-Mar 04-Mar 05-Mar 06-Mar 07-Mar 08-Mar 09-Mar 10-Mar 11-Mar 12-Mar 13-Mar 14-Mar 15-Mar 16-Mar 17-Mar 18-Mar 19-Mar 20-Mar 21-Mar 22-Mar 23-Mar 24-Mar 25-Mar 26-Mar 27-Mar 28-Mar 29-Mar 30-Mar 31-Mar 01-Apr 02-Apr 192.16 194.78 214.98 145.29 189.83 165.1 196.56 193.63 220.43 212.14 205.08 233.91 205.41 223.68 177.19 225.35 202.49 186.42 220.63 227.64 230.68 240.33 232.86 197.06 179.58 215.88 216.81 215.2 85.61 125.51 182.13 224.06 168.05 181.68 180.98 271.06 221.41 177.48 198.61 223.51 268.87 204.16 204.65 218.66 161.53 303.02 99.52 211.08 208.3 221.63 1322.98 1473.11 1535.62 1220.72 1424.72 1479.99 1481.47 208.4 210.22 236.48 198.25 162.34 198.59 176.79 258.11 234.16 216.23 196.82 211.89 223.29 249.81 279.19 231.51 248.99 218.26 235.87 244.09 231.93 241.53 231.83 247.89 180.96 195.55 296.68 262.92 86.6 151.98 266.44 230 230.41 224.24 228.82 237.96 253.84 213.97 223.67 211 272.71 216.14 226.19 241.23 180 341.12 135.44 247.62 186.76 251.49 1444.47 18.6 26.867142 1641.5 15.67465 25.729935 1651.4 14.40845 23.794115 1441.13 15.76197 22.71505 1619.24 16.32958 26.441505 1570.94 16.94085 26.613051 1662.56 14.93239 24.826002 99 | P a g e 03-Apr 04-Apr 05-Apr 06-Apr 07-Apr 08-Apr 09-Apr 10-Apr 11-Apr 12-Apr 13-Apr 14-Apr 15-Apr 16-Apr 17-Apr 18-Apr 19-Apr 20-Apr 21-Apr 22-Apr 23-Apr 24-Apr 25-Apr 26-Apr 27-Apr 28-Apr 29-Apr 30-Apr 01-May 02-May 03-May 04-May 05-May 06-May 07-May 08-May 09-May 10-May 11-May 12-May 13-May 14-May 15-May 16-May 17-May 18-May 19-May 20-May 21-May 22-May 225.83 212.09 175 223.82 227.31 210.9 228.28 190.29 200.36 230.92 177.93 211.74 231.06 221.66 170.44 235.76 163.16 147.35 206.49 200.81 197.49 210.53 214.96 225.53 98.84 213.6 236.3 239.23 244.69 232.15 171.13 241.09 227.04 226.18 242.45 238.14 243.14 220.75 238.63 240.56 245.45 245 245.93 240.8 205.36 224 205 193 204 222 1455.96 1479.51 1340.79 1490.34 1589.17 1677.12 1449.36 267.71 232.42 230.41 257.37 258.7 244.38 263.2 220.63 240 240 200.59 216.3 253 228.21 174.36 255.89 190.61 158.05 242.1 213.52 239.43 229.05 235.41 239.62 124.72 243.13 257.99 272.63 268 272.33 185.68 271.98 252.06 247.94 278.68 271.53 274.78 230.59 277.73 276.94 269.35 276.22 277.99 284.51 248.82 225.06 230.97 227.64 216.8 258.59 1714.69 13.3169 22.834358 1568.35 16.02394 25.131152 1508.17 16.15493 24.36438 1678.42 16.19859 27.18804 1782.65 16.80986 29.966095 1893.33 17.72676 33.562608 1657.66 17.72676 29.384942 100 | P a g e 23-May 24-May 25-May 26-May 27-May 28-May 29-May 30-May 31-May 196 46 210.01 224.01 208 169 210 225 222 1292.02 1554 249.78 73.6 222.13 172.54 331.46 172.18 241.17 247.44 255.97 1460.52 16.7662 24.487366 1791.79 13.70986 24.565189 101 | P a g e Table 8.1. Soda loss from Screens as Reject in WFL and SFL Screen Loss SFL % Washable Soda loss Mass of Pulp (MT) Total Soda Loss (MT) % Washable Soda loss Mass of Pulp (MT) Total Washable Soda Loss (MT) % Total Soda (TTA Na2O, Kg/MT) WFL Total Soda Loss (MT) Total Washable Soda Loss (MT) Date Shift Total Loss (MT) TTA (Na2CO3) % Total Soda (TTA Na2O, Kg/MT) 1.489 52.76 50.9 2.5946 0.136891 0.1320651 81.82 56.29 1.36692 0.111841 0.0769439 13.641 52.76 50.9 2.5208 0.132997 0.1283087 81.82 56.29 1.23765 0.101265 0.0696673 10.123 52.76 50.9 2.4335 0.128391 0.1238652 81.82 56.29 1.08975 0.089163 0.061342 4.394 52.76 50.9 1.9861 0.104787 0.1010925 81.82 56.29 1.02876 0.084173 0.0579089 17.856 52.76 50.9 2.631 0.138812 0.1339179 81.82 56.29 1.49196 0.122072 0.0839824 22.419 52.76 50.9 2.6129 0.137857 0.1329966 81.82 56.29 1.501656 0.122865 0.0845282 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 08-Jun 52.76 52.76 50.9 50.9 2.553 2.3018 0.134696 0.1299477 0.121443 0.1171616 81.82 81.82 56.29 56.29 C A B C A B C A B C A B C A B C A B C A B C 22.625 1.550844 0.12689 0.087297 1.220496 0.099861 0.0687017 2.468 33.3 31.9 34.6 32.9 34.5 29.6 28.4 26.3 27.1 29.3 27.2 29.6 29.8 29.4 33.2 34.1 30.4 33.4 29.2 31.4 32.7 33.3 -6.834 52.76 50.9 2.5386 0.133937 0.1292147 81.82 56.29 1.515984 0.124038 0.0853347 -9.661 52.76 50.9 2.4151 0.127421 0.1229286 81.82 56.29 1.65342 0.135283 0.093071 1.108 52.76 50.9 1.2624 0.066604 0.0642562 81.82 56.29 1.338948 0.109553 0.0753694 3.38 52.76 50.9 1.7638 0.093058 0.0897774 81.82 56.29 1.451868 0.118792 0.0817256 16.98 52.76 50.9 2.2977 0.121227 0.1169529 81.82 56.29 1.024776 0.083847 0.0576846 -2.08 52.76 50.9 2.2236 0.117317 0.1131812 81.82 56.29 1.601196 0.13101 0.0901313 6.93 52.76 50.9 2.6725 0.141001 0.1360303 81.82 56.29 1.62486 0.132946 0.0914634 11.62 52.76 50.9 2.6067 0.137529 0.132681 81.82 56.29 1.594092 0.130429 0.0897314 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 52.76 50.9 2.8528 0.150514 0.1452075 81.82 56.29 A B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.17 29.6 29.2 32.9 33.7 30.8 28.6 29.4 33.1 26.8 33.4 0 27.8 30.8 34.4 35.4 29.5 27.8 30.2 30.2 29.8 28.8 28.2 27.9 32 29.2 27.3 34.6 29.4 26.7 1.456596 0.119179 0.0819918 103 | P a g e Table 8.2. Combined soda loss from Screens as Reject in WFL and SFL Screen Loss Date Shift Total Loss (MT) TTA (Na2 CO3) Total Soda Loss (MT) % Total Loss in Screen Total Washable Soda Loss (MT) % Washable Loss in Screen Combined % % General General Total Washab Soda le Soda Loss Loss % Loss for Total Soda (ORE) Avg % Loss for Total Soda (ORE) % Loss for Washable Soda (ORE) Avg % Loss for Washable Soda (ORE) 2.81 0.2090091 16.70467 14.0368749 0.187174 2.34 0.201 0.1572814 0.167 1.489 0.248732 13.641 0.234262 0.197976 1.717337 1.45133083 0.181292 0.1532108 10.123 0.217555 0.1852072 2.149114 1.82956809 0.187531 0.1596473 4.394 0.18896 0.1590014 4.300405 3.61860242 2.809 2.340 0.192986 0.201 0.1623892 0.167 17.856 0.260884 0.2179003 1.461042 1.22031994 0.212719 0.1776715 22.419 0.260722 0.2175248 1.162952 0.2172447 1.156183 0.97026998 0.96019761 0.192005 0.204507 0.1601927 0.1698406 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun C A B C A B C A B C A B C A B C A B C A 22.625 33.3 31.9 34.6 32.9 34.5 29.6 28.4 26.3 27.1 29.3 27.2 29.6 29.8 29.4 33.2 34.1 30.4 33.4 29.2 31.4 0.261586 104 | P a g e 2.468 0.221304 0.1858633 8.966935 7.53092949 0.205011 0.1721792 -6.834 0.257974 0.2145495 -3.77487 -3.1394422 0.205117 0.1705896 -9.661 0.262704 0.2159996 -2.71922 -2.2357893 0.206452 0.1697489 1.108 0.176157 0.1396255 15.89864 12.6015833 0.22964 0.1820175 3.38 0.21185 0.1715031 6.267749 5.07405532 0.187157 0.1515125 16.98 0.205074 0.1746376 1.207737 1.02848982 0.20214 0.1721391 -2.08 0.248327 0.2033126 -11.9388 -9.7746424 0.20823 0.1704841 6.93 0.273947 0.2274936 3.953061 3.28273621 0.203429 0.168933 11.62 0.267958 0.2224125 2.306008 1.91404878 0.202346 0.1679527 07-Jun 08-Jun 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 0.2271993 5.216488 4.39457077 0.213695 0.180025 B C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.17 32.7 33.3 29.6 29.2 32.9 33.7 30.8 28.6 29.4 33.1 26.8 33.4 0 27.8 30.8 34.4 35.4 29.5 27.8 30.2 30.2 29.8 28.8 28.2 27.9 32 29.2 27.3 34.6 29.4 26.7 0.269692 105 | P a g e Table 9.6. ESP ORE Loss Recovery 2 SFL Recovery 1 Total WFL Date Shift Total Loss (MT) % Loss (ORE) % Loss (ORE) WL Consumed (TTA Na2O MT) Avg % Loss (ORE) % Loss through ESP Avg % Loss (ORE) % Loss through ESP WL Consumed (TTA Na2O MT) % General Loss though ESP % General Loss though ESP Avg % Loss (ORE) % General Loss though ESP 0.817 11.48 0.580 8.15 1.397 19.63 1.49 0.72 64.08 0.51 45.53 13.64 0.74 6.99 0.52 4.97 10.12 0.82 9.43 0.58 6.70 4.39 0.97 21.71 0.82 11.48 0.69 0.58 15.43 8.15 1.40 19.63 17.86 0.78 5.34 0.55 3.80 22.42 0.70 4.26 0.50 3.02 RESULT 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 25.0 26.2 21.2 27.5 24.7 22.0 18.7 21.3 25.8 22.6 13.4 16.7 24.2 23.6 24.6 28.4 24.6 27.4 23.2 24.2 24.6 0.75 4.22 0.53 3.00 C A B C A B C A B C A B C A B C A B C A B 22.63 21.8 22.3 16.4 16.9 21.7 16.4 16.6 16.9 16.7 17.1 16.9 11.2 16.7 16.8 16.6 16.2 17.2 22.1 22.4 16.6 16.9 2.47 0.88 38.66 0.63 27.47 -6.83 0.76 -13.96 0.54 -9.92 -9.66 0.75 -9.88 0.53 -7.02 1.11 1.24 86.11 0.88 61.19 3.38 0.84 28.23 0.60 20.06 16.98 0.94 5.62 0.67 3.99 -2.08 0.80 -45.87 0.57 -32.60 6.93 0.71 13.77 0.50 9.78 11.62 0.72 8.21 0.51 5.83 08-Jun 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun 0.76 18.45 0.54 13.11 C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B 5.17 11.4 16.9 16.8 16.6 22.1 16.4 21.9 17.1 21.8 17.0 22.2 11.0 16.3 16.9 21.9 11.5 10.7 17.0 16.7 16.4 22.4 21.7 22.0 16.6 21.9 22.3 16.6 19.4 23.4 10.2 19.6 20.2 23.2 25.0 21.4 24.3 23.6 26.2 16.7 22.7 3.8 0.0 12.6 23.5 22.1 23.3 19.4 19.5 19.7 19.2 24.9 25.8 27.0 21.5 23.3 25.0 23.4 26.8 25.4 20.9 107 | P a g e Table 10.1. Average ORE based on stock SFL Date 01-Jun 01-Jun 01-Jun 02-Jun 02-Jun 02-Jun 03-Jun 03-Jun 03-Jun 04-Jun 04-Jun 04-Jun 05-Jun 05-Jun 05-Jun 06-Jun 06-Jun 06-Jun 07-Jun 07-Jun 07-Jun 08-Jun 08-Jun 08-Jun 09-Jun 09-Jun 09-Jun 10-Jun 10-Jun 10-Jun 11-Jun 11-Jun 11-Jun 12-Jun 12-Jun 12-Jun 13-Jun 13-Jun 13-Jun 14-Jun Shift C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B C A B C Total Loss (MT) 1.489 WFL Average ORE 13.641 10.123 4.394 17.856 22.419 22.625 2.468 -6.834 -9.661 1.108 3.38 16.98 -2.08 WL WL Consumed Consumed Total WL % Loss ORE (TTA (TTA Consumed Na2O MT) Na2O MT) 24.98705 21.845 46.83205 26.1545 22.28 48.4345 1.1205 98.88 21.1951 16.427 37.6221 27.47343 16.923 44.39643 24.6942 21.713 46.4072 10.557 89.443 22.0274 16.387 38.4144 18.66867 16.616 35.28467 21.32362 16.904 38.22762 8.726 91.274 25.78394 16.714 42.49794 22.63644 17.094 39.73044 13.41116 16.891 30.30216 4.4876 95.512 16.7262 11.155 27.8812 24.22728 16.749 40.97628 23.63286 16.811 40.44386 14.559 85.441 24.60912 16.613 41.22212 28.35826 16.183 44.54126 24.55047 17.197 41.74747 16.51 83.49 27.35278 22.148 49.50078 23.20928 22.443 45.65228 24.21172 16.555 40.76672 17.688 82.312 24.62994 16.862 41.49194 19.581 11.354 30.935 20.15745 16.886 37.04345 2.2863 97.714 23.19216 16.777 39.96916 24.9565 16.592 41.5485 21.44608 22.103 43.54908 -5.434 105.43 24.28979 16.382 40.67179 23.60832 21.886 45.49432 26.16104 17.08 43.24104 -7.592 107.59 16.74419 21.767 38.51119 22.67496 17.01 39.68496 3.834 22.177 26.011 1.4444 98.556 0 11.014 11.014 12.61416 16.339 28.95316 23.46552 16.862 40.32752 2.986 97.014 22.0563 21.857 43.9133 23.2686 11.494 34.7626 19.43172 10.73 30.16172 16.737 83.263 19.52412 17.003 36.52712 19.67256 16.718 36.39056 -1.744 101.74 94.0003 14-Jun 14-Jun 15-Jun 15-Jun 15-Jun 16-Jun 16-Jun 16-Jun 17-Jun 17-Jun 17-Jun A B C A B C A B C A B 6.93 11.62 5.17 19.15182 24.88068 25.8447 26.99169 21.5016 23.2848 24.98796 23.3709 26.8422 25.43688 20.92122 16.433 22.4 21.706 22.049 16.572 21.895 22.266 16.621 19.353 23.439 10.212 35.58482 47.28068 47.5507 49.04069 38.0736 45.1798 47.25396 39.9919 46.1952 48.87588 31.13322 5.1461 94.854 8.7747 91.225 4.0965 95.903 109 | P a g e