Water Conservation In Pulp & Paper Industry Through Innovative Water Management & Modeling Techniques. R. M. Mathur, B.P. Thapliyal, A.K.Goel Central Pulp And Paper Research Institute P.O.Box. 174, Saharanpur Central Pulp & Paper Research Institute , Saharanpur •Pulp and paper industry is one of the major water consuming industries. •Water is used for a variety of processes and gets contaminated during processing with raw materials,chemicals, by-products & residues. •Treatment of contaminated wastewater has always been an expensive & technically challenging subject. Central Pulp & Paper Research Institute , Saharanpur Water Consumption In Indian Paper Mills Raw Material Bamboo Wood+Bamboo Wood+Bamboo Wood+Bamboo+RCF Agro Residues RCF Market Pulp Products Writing/Printing Paper Writing/Printing Paper Writing/Printing Paper Unbleached varieties News print Writing/Printing Paper News print/ writing Printing Speciality Paper Water Consumption m3/t 100-120 90-125 80-120 95 100 35 90 Central Pulp & Paper Research Institute , Saharanpur Typical Water Consumption in Wood/ Bamboo Based Mill Others 11% Bleaching 30% Stock Preparation 4% Power House 6% Chemical Recovery 10% Pulping 14% Paper Machine 25% Central Pulp & Paper Research Institute . Saharanpur . • recycle and • regeneration opportunities. Saharanpur . Central Pulp & Paper Research Institute .Water management techniques can prove to be highly effective as they enable efficient usage of water with considerations of • reuse. Central Pulp & Paper Research Institute . Saharanpur .Process Integration The application of methodologies aimed at designing/modernizing an Industrial Facility by optimizing its various constituent units rather than improving each individual unit by itself. Saharanpur .Process Integration Methods •Classical pinch based •Mathematical programming based Central Pulp & Paper Research Institute . Central Pulp & Paper Research Institute . •Water surplus diagrams are utilized to target water requirement. Saharanpur .Pinch Based Approach •Graphical technique to minimize fresh water flow •An extension of the pinch analysis technique for heat integration. Purity Fresh Water Water Sources Concentration Water Demands Water Pinch Waste water •Not suitable for multiple contaminant systems Central Pulp & Paper Research Institute . Saharanpur Water Flow .Water Pinch – Composite Curves •Each water related process operation considered as having water inputs and output streams and composite of water demand (Input) and water sources (Output) can be constructed. •A system of equations is solved with constraints to get values for various water streams.Mathematical Programming Approach •The pinch point ( pinch concentration and pinch mass load) is calculated by application of Composite Table Algorithm (CTA). •A Network is generated by applying Nearest Neighbor Algorithm (NNA) •Network of all possible matches is created and the system is optimized for minimum fresh water requirement based on capital/operating expenses. Central Pulp & Paper Research Institute . Saharanpur . reuse & regeneration. •Provides insight into water targeting with a consideration of recycle. Central Pulp & Paper Research Institute . Saharanpur .Advantages of Mathematical Programming Approach •Provides a robust way of water network design. Saharanpur . •This demand may be fulfilled by mixing fresh water with effluent streams from other water using operations and regenerated water. •The process outlet streams may be used to satisfy the demand of other operations. Central Pulp & Paper Research Institute . sent to treatment units or discharged without treatment. •Each water using operation demands a certain quality and quantity of water to satisfy its process needs.Basic Network Structure •A basic integrated water network consists of a set of water using and water treating operations. Unit operation mass flow C P in C Water out C P out Process C Water in C P in Concetration C W out C P out C W in m. Mass flow rate Central Pulp & Paper Research Institute . Saharanpur . Saharanpur .Water limiting profile Process 4 800 Concetration Limiting Profile curve Process 3 400 Water Supply Line 100 Process 1& 2 m. Mass flow rate Central Pulp & Paper Research Institute . Mass flow rate m. Printing and writing papers •Raw materials .000 tpa •Products .hardwood and bamboo .CASE STUDY Mill Details:•Production 75. ratio(84:16) •6 paper machines •3 stationary batch digesters •Pulp is bleached by using C/DEopD1D2 bleaching sequence. • Central Pulp & Paper Research Institute . Saharanpur . Central Pulp & Paper Research Institute . •A complete water balance of the pulp mills was prepared using online & portable flow meters. •The water samples from various streams were characterized with respect to their pollution load. Saharanpur .METHODOLOGY •The study was carried out for two contaminants (TS & COD) in the bleach plant for reuse & recycle options. Saharanpur .Water Balance Flow Diagram for Mill ( All Figures in m3/hr) Central Pulp & Paper Research Institute . The limiting contaminant levels are fixed at 10 % above the current values. •Restriction on re use of water streams •All matches prohibited by pH are disallowed.Data Extraction: •All operations assumed to be fixed contaminant (FC) and fixed flowrate operations type. Saharanpur . •Order and flowrate from one process to another is maintained • Central Pulp & Paper Research Institute . Saharanpur . Extracted Flow Diagram Central Pulp & Paper Research Institute .368 D1 1854 403 CD Pulp washing EOP Pulp washing 368 2970 403 2081 367 1910 373 1447 847 656 S1 D2 D3 1190 367 1037 373 S2 S3 D1 Pulp washing D4 990 847 D2 Pulp washing S4 D5 656 Decker Pulp washing S5 Fig. Saharanpur .No Detail of Streams Fin Cin max m3/hr TS COD ppm ppm 4457 3827 3683 3134 2617 1854 1190 1037 990 656 Fout m3/hr 63 51 57 63 63 Cin m ax COD ppm 2970 2081 1910 1447 656 TS ppm 8797 6982 5674 5063 2617 1 2 3 4 5 C/D Washer 368 EOP Washer 403 D1 Washer D2 Washer Decker washer 367 373 847 Central Pulp & Paper Research Institute .Flow rate and Contamination Data for Mill S. 1 423.4 65.6 149. Net Flow..2 293.7 326. C . Cmin Concentration. Flow ppm t/hr 600 0 d 847 656 847 s 847 Load Kg/hr 0 47.4 47. FlowSource Flow x ( C2 – C1)/1000 Cumulative Load.5 471.1 980.0 d d d s d s s s 373 367 403 373 368 367 403 368 990 1037 1190 1447 1854 1910 2081 2970 3000 0 373 740 1143 770 1138 771 368 0 Pinch conc.9 1308.4 436.0 Slope 0 72.9 62. Central Pulp & Paper Research Institute .5 113.2 0..8 327.9 785.0 17.0 178. kg/hr (m) 0 47.0 ……….3 47.0 1308.8 313..3 849.4 0.4 63.m…….6 444.2 471.4 440. Saharanpur Pinch Load Pinch point .7 131.Composite Table Algorithm Flow = FlowDemand . kg/hr Central Pulp & Paper Research Institute .Limiting Composite Curve Limiting Composite Curve Contaminant Concentration. Saharanpur . ppm 3000 2500 2000 1500 1000 500 Water Composite curve Pinch Concentration Pinch Line Pinch Load 0 250 500 750 1000 1250 1500 Contaminant Load. than whatever is available of that source is used completely & next neighbor is considered to satisfy the demand. Saharanpur .Nearest Neighbour Algorithm ØSources which are immediate higher/ lower in concentration for a demand are mixed in ratio determined by mass balance to satisfy the demand. Central Pulp & Paper Research Institute . ØIf the required flow rate is not available for a source. DP + FS (K+1). Saharanpur . Central Pulp & Paper Research Institute .DP CS(K+1) =FDP CDP Where F&C are flowrate & concentration SK & S(K+1) are immediate cleaner& dirtier sources ( Nearest Neighbour) DP is the particular demand. Dp CSK +FS (K+1). DP = FDP FSK .Nearest Neighbour Algorithm The mass balance equations areFSK . 0 63 Used 191.0 0.0 51.0 0.0 179.W.0 0.0 0.0 125.0 47.0 0. Saharanpur .0 63.0 179.0 784.0 76.0 76.0 305.0 EOP Washer D1 Washer D2 Washer Decker Washer D4 {373} D5 {847} 76.0 0.0 66.0 57.0 6.0 37.0 275.0 63.0 47.0 708.0 235.0 0.Fresh water Network before study No.0 63.0 51.0 63.0 0.0 0.0 306.0 51.0 63.0 Extra D2 {403} D3 {367} 50.0 40.0 C/D Washer D1 {368} 65.0 37. B/W C/D Washer o/l EOP Washer o/l D1 Washer o/l D2 Washer o/l Decker Washer o/l F (m3/hr) Available 191 37 47 304 351 311 310 784 63.0 250.0 55.0 4.0 57.0 63. Streams Name S1 S2 S3 S4 S5 S6 S7 S8 P1 P2 P3 P4 P5 Freshwater B/W from PM 4 Feed from BSW C/D Washer B/W EOP Washer B/W D1 Washer B/W D2 Washer B/W D.0 57.0 Central Pulp & Paper Research Institute .0 240. Saharanpur .0 234.5 290.0 67.0 √ 50.0 0.0 47.0√ 37.0 305.0 5.0 30.0 716.0 47.0 21.0 21.0 Central Pulp & Paper Research Institute .0 51.0 310. Streams Name S1 S2 S3 S4 S5 S6 S7 S8 P1 P2 P3 P4 P5 Freshwater B/W from PM 4 Feed from BSW C/D Washer B/W EOP Washer B/W D1 Washer B/W D2 Washer B/W D.0 63.0 37.0 63.0 290.0 784.0 √ 0.0 0.0 0.0 0.0 C/D Washer D1 {368} 70.0 √ 0.5 63.0 63.0 57.0 63.0 17.0 Extra D2 {403} D3 {367} 30.0 234.Fresh Water Network After Study No.W.5 30.0 √ 21.0 242.0 57.0 11.0 70.0 √ 0.0 √ 0.5 EOP Washer D1 Washer D2 Washer Decker Washer D4 {373} D5 {847} 70.0 0. B/W C/D Washer o/l EOP Washer o/l D1 Washer o/l D2 Washer o/l Decker Washer o/l F (m3/hr) Available 191 37 47 304 351 311 310 784 63 51 57 63 63 Used 121.0 301. Proposed Water Balance Network for Mill -1 Central Pulp & Paper Research Institute . Saharanpur . Saharanpur .Results for Mill –I Particulars Min. Fresh Water 191 Min. Fresh Water after PI Consumption before PI 121 (considering TS and COD as contaminants) Fresh Water Saving % 36 Units m3/hr M3/hr - Central Pulp & Paper Research Institute . Fw Min. Central Pulp & Paper Research Institute . •Application of the mathematical programming model developed for water minimization has shown scope of water savings in both the mills after selecting suitable water networks. Saharanpur .Conclusion •The study conducted in selected mills in the pulp mill section has shown that PI studies can be a valuable tool for water conservation. Saharanpur .THANK YOU Central Pulp & Paper Research Institute .