[{"data":1,"prerenderedAt":574},["ShallowReactive",2],{"site-footer-common":3,"glossary:recausticising":45,"glossary-related:recausticising":183},{"id":4,"extension":5,"footer":6,"meta":40,"navbar":41,"stem":43,"__hash__":44},"common\u002Fcommon.yml","yml",{"tagline":7,"links":8,"sections":9},"Acoustic cleaning intelligence for industrial fouling, soot, ash, dust and build-up.",[],[10,19,31],{"title":11,"links":12},"Product",[13,16],{"label":14,"to":15},"How it works","\u002F#product",{"label":17,"to":18},"Cost assessment","\u002F#hero",{"title":20,"links":21},"Company",[22,25,28],{"label":23,"to":24},"What we build","\u002F#about",{"label":26,"to":27},"Careers","\u002F#careers",{"label":29,"to":30},"Contact","\u002F#contact",{"title":32,"links":33},"Resources",[34,37],{"label":35,"to":36},"Blog","\u002Fresources\u002Fblog",{"label":38,"to":39},"Glossary","\u002Fglossary",{},{"links":42},[],"common","YocmZRy1AYfBbpgGVms-zhdiABlF8VTxHx6h4rDmZBA",{"id":46,"title":47,"aliases":48,"body":53,"category":164,"description":165,"extension":166,"meta":167,"navigation":168,"path":169,"relatedTerms":170,"seo":174,"sources":177,"stem":181,"term":47,"__hash__":182},"glossary\u002Fglossary\u002Frecausticising.md","Recausticising",[49,50,51,52],"recausticizing","causticising","causticizing","causticising plant",{"type":54,"value":55,"toc":158},"minimark",[56,78,83,86,124,131,135],[57,58,59,62,63,66,67,72,73,77],"p",{},[60,61,47],"strong",{}," (also ",[64,65,49],"em",{}," in US spelling) is the chemical step that regenerates kraft cooking liquor by reacting green liquor (sodium carbonate from the ",[68,69,71],"a",{"href":70},"\u002Fglossary\u002Fsmelt-dissolving-tank","smelt dissolving tank",") with burnt lime (CaO from the ",[68,74,76],{"href":75},"\u002Fglossary\u002Flime-kiln","lime kiln",") to produce white liquor (sodium hydroxide + sodium sulphide) and lime mud (CaCO₃). The white liquor is returned to the digester for pulping; the lime mud goes back to the lime kiln for re-calcination.",[79,80,82],"h2",{"id":81},"the-closed-chemical-cycle","The closed chemical cycle",[57,84,85],{},"Kraft recovery is a closed loop:",[87,88,89,97,104,115,118,121],"ol",{},[90,91,92,93],"li",{},"Pulping consumes white liquor; produces ",[68,94,96],{"href":95},"\u002Fglossary\u002Fblack-liquor","black liquor",[90,98,99,100],{},"Black liquor concentrated in evaporators, burned in the ",[68,101,103],{"href":102},"\u002Fglossary\u002Frecovery-boiler","recovery boiler",[90,105,106,107,111,112],{},"Recovery boiler produces ",[68,108,110],{"href":109},"\u002Fglossary\u002Fsmelt","smelt",", which dissolves into green liquor in the ",[68,113,114],{"href":70},"SDT",[90,116,117],{},"Recausticising converts green liquor + burnt lime → white liquor + lime mud",[90,119,120],{},"Lime kiln calcines lime mud → burnt lime",[90,122,123],{},"Burnt lime returns to recausticising",[57,125,126,130],{},[68,127,129],{"href":128},"\u002Fglossary\u002Fsonic-horn","Sonic horns"," appear at several points around this loop, principally on the recovery boiler, SDT vent stack, lime-kiln preheater and lime-kiln ESP hopper.",[79,132,134],{"id":133},"related-terms","Related terms",[136,137,138,143,148,153],"ul",{},[90,139,140],{},[68,141,142],{"href":95},"Black liquor",[90,144,145],{},[68,146,147],{"href":109},"Smelt",[90,149,150],{},[68,151,152],{"href":70},"Smelt dissolving tank (SDT)",[90,154,155],{},[68,156,157],{"href":75},"Lime kiln",{"title":159,"searchDepth":160,"depth":160,"links":161},"",2,[162,163],{"id":81,"depth":160,"text":82},{"id":133,"depth":160,"text":134},"pulp-paper","Recausticising (also recausticizing in US spelling) is the chemical step that regenerates kraft cooking liquor by reacting green liquor (sodium carbonate from the smelt dissolving tank) with burnt lime (CaO from the lime kiln) to produce white liquor (sodium hydroxide + sodium sulphide) and lime mud (CaCO₃). The white liquor is returned to the digester for pulping; the lime mud goes back to the lime kiln for re-calcination.","md",{},true,"\u002Fglossary\u002Frecausticising",[171,110,172,173],"black-liquor","smelt-dissolving-tank","lime-kiln",{"title":175,"description":176},"Recausticising — regenerating kraft cooking liquor from green liquor and lime","Recausticising converts green liquor (sodium carbonate) and burnt lime back into white liquor (sodium hydroxide and sulphide) for re-use in kraft pulping.",[178],{"title":179,"url":180},"Wikipedia — Kraft process","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FKraft_process","glossary\u002Frecausticising","JpSdvS8pBLnO_IYyDt3rZMJhESv-c65so_nB-QqIwiI",[184,291,382,461],{"id":185,"title":142,"aliases":186,"body":190,"category":164,"description":276,"extension":166,"meta":277,"navigation":168,"path":95,"relatedTerms":278,"seo":282,"sources":285,"stem":289,"term":142,"__hash__":290},"glossary\u002Fglossary\u002Fblack-liquor.md",[187,188,189],"kraft black liquor","weak black liquor","heavy black liquor",{"type":54,"value":191,"toc":272},[192,205,219,223,250,252],[57,193,194,196,197,201,202,204],{},[60,195,142],{}," is the concentrated spent cooking liquor from kraft pulping, containing dissolved lignin, hemicellulose, sodium carbonate, sodium sulphate and other inorganic compounds. After pulping, the weak black liquor (~15% solids) is concentrated in a ",[68,198,200],{"href":199},"\u002Fglossary\u002Fmulti-effect-evaporator","multi-effect evaporator"," train to heavy black liquor (~70–75% solids) and burned in the ",[68,203,103],{"href":102},". Combustion serves three purposes simultaneously:",[87,206,207,210,216],{},[90,208,209],{},"Generate steam and electrical power for the mill",[90,211,212,213,215],{},"Recover the sodium and sulphur chemicals as ",[68,214,110],{"href":109}," for re-use in pulping",[90,217,218],{},"Destroy the organic-loaded waste stream",[79,220,222],{"id":221},"why-it-matters-for-cleaning","Why it matters for cleaning",[57,224,225,226,230,231,235,236,240,241,245,246,249],{},"Burning concentrated black liquor produces uniquely sticky, alkali-rich ",[68,227,229],{"href":228},"\u002Fglossary\u002Fcarry-over","carry-over"," that deposits on the recovery-boiler ",[68,232,234],{"href":233},"\u002Fglossary\u002Fgenerating-bank","generating bank",", ",[68,237,239],{"href":238},"\u002Fglossary\u002Fsuperheater","superheater"," and ",[68,242,244],{"href":243},"\u002Fglossary\u002Feconomiser","economiser"," tubes. Black-liquor combustion is what makes recovery boilers the iconic application for ",[68,247,248],{"href":128},"sonic horns"," — no other industrial-boiler fuel produces fouling so aggressive yet so responsive to acoustic cleaning.",[79,251,134],{"id":133},[136,253,254,259,263,268],{},[90,255,256],{},[68,257,258],{"href":102},"Recovery boiler",[90,260,261],{},[68,262,147],{"href":109},[90,264,265],{},[68,266,267],{"href":199},"Multi-effect evaporator",[90,269,270],{},[68,271,47],{"href":169},{"title":159,"searchDepth":160,"depth":160,"links":273},[274,275],{"id":221,"depth":160,"text":222},{"id":133,"depth":160,"text":134},"Black liquor is the concentrated spent cooking liquor from kraft pulping, containing dissolved lignin, hemicellulose, sodium carbonate, sodium sulphate and other inorganic compounds. After pulping, the weak black liquor (~15% solids) is concentrated in a multi-effect evaporator train to heavy black liquor (~70–75% solids) and burned in the recovery boiler. Combustion serves three purposes simultaneously:",{},[279,110,280,281],"recovery-boiler","multi-effect-evaporator","recausticising",{"title":283,"description":284},"Black liquor — concentrated kraft pulping spent liquor burned in recovery boilers","Black liquor is the concentrated spent cooking liquor from kraft pulping. It is burned in the recovery boiler to generate steam, power and to recover the pulping chemicals.",[286],{"title":287,"url":288},"Wikipedia — Black liquor","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FBlack_liquor","glossary\u002Fblack-liquor","gg0HQ0VOAJ4Y-oJjXnj1VtHfSrn5coQQ7Kgldrp5uaY",{"id":292,"title":147,"aliases":293,"body":296,"category":164,"description":369,"extension":166,"meta":370,"navigation":168,"path":109,"relatedTerms":371,"seo":372,"sources":375,"stem":379,"term":380,"__hash__":381},"glossary\u002Fglossary\u002Fsmelt.md",[294,295],"kraft smelt","recovery boiler smelt",{"type":54,"value":297,"toc":364},[298,311,315,332,336,344,346],[57,299,300,302,303,306,307,310],{},[60,301,147],{}," is the molten inorganic phase recovered from the bottom of a ",[68,304,305],{"href":102},"kraft recovery boiler",". It consists primarily of sodium carbonate (Na₂CO₃) and sodium sulphide (Na₂S) at ~800 °C and is the chemical-recovery product of black-liquor combustion. Smelt is discharged from the boiler bottom through spouts into a ",[68,308,309],{"href":70},"smelt dissolving tank (SDT)"," where it is quenched into water to form green liquor.",[79,312,314],{"id":313},"smelt-carry-over","Smelt carry-over",[57,316,317,318,320,321,235,323,240,325,327,328,331],{},"A portion of the inorganic burden — sodium sulphate, sodium chloride, fume — does not settle as smelt but is entrained upward in the flue gas as ",[68,319,229],{"href":228},". This carry-over is what fouls the ",[68,322,234],{"href":233},[68,324,239],{"href":238},[68,326,244],{"href":243},", and is the target of ",[68,329,330],{"href":128},"sonic-horn"," cleaning.",[79,333,335],{"id":334},"safety","Safety",[57,337,338,339,343],{},"Molten smelt contact with water is the leading documented cause of catastrophic recovery-boiler explosions. ",[68,340,342],{"href":341},"\u002Fglossary\u002Fblrbac","BLRBAC"," Recommended Good Practices govern smelt-handling procedures and any change to cleaning systems — including acoustic-horn additions — requires review against the smelt-water-explosion protocols.",[79,345,134],{"id":133},[136,347,348,352,356,360],{},[90,349,350],{},[68,351,258],{"href":102},[90,353,354],{},[68,355,142],{"href":95},[90,357,358],{},[68,359,152],{"href":70},[90,361,362],{},[68,363,47],{"href":169},{"title":159,"searchDepth":160,"depth":160,"links":365},[366,367,368],{"id":313,"depth":160,"text":314},{"id":334,"depth":160,"text":335},{"id":133,"depth":160,"text":134},"Smelt is the molten inorganic phase recovered from the bottom of a kraft recovery boiler. It consists primarily of sodium carbonate (Na₂CO₃) and sodium sulphide (Na₂S) at ~800 °C and is the chemical-recovery product of black-liquor combustion. Smelt is discharged from the boiler bottom through spouts into a smelt dissolving tank (SDT) where it is quenched into water to form green liquor.",{},[279,171,172,281],{"title":373,"description":374},"Smelt — molten inorganic recovered from kraft recovery boilers","Smelt is the molten sodium carbonate and sulphide mixture that accumulates in the bottom of a kraft recovery boiler. It is dissolved into green liquor and recausticised to pulping reagent.",[376],{"title":377,"url":378},"Wikipedia — Recovery boiler","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FRecovery_boiler","glossary\u002Fsmelt","Smelt (recovery boiler)","5L_O2eD74h-akmEsbjqyXkvnBQBYbTR5ZDvCt6_gCD4",{"id":383,"title":152,"aliases":384,"body":387,"category":164,"description":450,"extension":166,"meta":451,"navigation":168,"path":70,"relatedTerms":452,"seo":453,"sources":456,"stem":458,"term":459,"__hash__":460},"glossary\u002Fglossary\u002Fsmelt-dissolving-tank.md",[114,385,386],"smelt dissolving tanks","dissolving tank",{"type":54,"value":388,"toc":445},[389,408,412,415,419,424,426],[57,390,391,392,394,395,397,398,400,401,404,405,407],{},"A ",[60,393,309],{}," receives molten ",[68,396,110],{"href":109}," discharged from the ",[68,399,103],{"href":102}," bottom and dissolves it into weak wash water to form ",[64,402,403],{},"green liquor"," (the alkaline solution sent on to the ",[68,406,281],{"href":169}," plant). Internal agitators and shatter jets break the smelt stream into small droplets to control the otherwise-violent quench reaction.",[79,409,411],{"id":410},"sdt-vent-stack","SDT vent stack",[57,413,414],{},"The dissolution is exothermic and steamy. SDT vent gas carries sodium-rich fume that condenses on the vent stack walls as a fine sticky deposit. Over time the build-up narrows the stack and disrupts vent flow.",[79,416,418],{"id":417},"sonic-horn-duty","Sonic-horn duty",[57,420,421,423],{},[68,422,129],{"href":128}," mounted on the SDT vent stack keep the sodium-fume deposit from consolidating, preventing the periodic outages otherwise needed for vent cleaning.",[79,425,134],{"id":133},[136,427,428,432,436,440],{},[90,429,430],{},[68,431,147],{"href":109},[90,433,434],{},[68,435,258],{"href":102},[90,437,438],{},[68,439,47],{"href":169},[90,441,442],{},[68,443,444],{"href":128},"Sonic horn",{"title":159,"searchDepth":160,"depth":160,"links":446},[447,448,449],{"id":410,"depth":160,"text":411},{"id":417,"depth":160,"text":418},{"id":133,"depth":160,"text":134},"A smelt dissolving tank (SDT) receives molten smelt discharged from the recovery boiler bottom and dissolves it into weak wash water to form green liquor (the alkaline solution sent on to the recausticising plant). Internal agitators and shatter jets break the smelt stream into small droplets to control the otherwise-violent quench reaction.",{},[110,279,281,330],{"title":454,"description":455},"Smelt dissolving tank (SDT) — quench tank that converts smelt to green liquor","An SDT receives molten smelt from the recovery boiler and dissolves it into weak wash to form green liquor. The vent stack accumulates sodium fume; sonic horns prevent stack-line plugging.",[457],{"title":377,"url":378},"glossary\u002Fsmelt-dissolving-tank","Smelt dissolving tank","FWvHPD8ZbLOg2d-uphcTK_-LT70su9VULlLehqK5XtY",{"id":462,"title":157,"aliases":463,"body":467,"category":164,"description":561,"extension":166,"meta":562,"navigation":168,"path":75,"relatedTerms":563,"seo":565,"sources":568,"stem":572,"term":157,"__hash__":573},"glossary\u002Fglossary\u002Flime-kiln.md",[464,465,466],"kraft lime kiln","rotary lime kiln","lime recovery kiln",{"type":54,"value":468,"toc":555},[469,482,486,493,497,505,509,514,534,536],[57,470,391,471,473,474,476,477,481],{},[60,472,76],{}," at a kraft pulp mill calcines spent lime mud (CaCO₃) back to burnt lime (CaO) at ~1,200 °C for re-use in the ",[68,475,281],{"href":169}," chemical-recovery cycle. The kiln is a long inclined rotating cylinder, similar in form to a ",[68,478,480],{"href":479},"\u002Fglossary\u002Frotary-kiln","cement rotary kiln"," but smaller and lower-temperature.",[79,483,485],{"id":484},"preheater-and-chain-section","Preheater and chain section",[57,487,488,489,492],{},"Most modern lime kilns have a preheater (often a chain section inside the kiln itself or an external preheater) where incoming damp lime mud is pre-dried by exhaust gas. The chain section accumulates lime-mud build-up — ",[64,490,491],{},"mud rings"," — that progressively narrow the gas path and reduce kiln throughput.",[79,494,496],{"id":495},"lime-kiln-esp","Lime-kiln ESP",[57,498,499,500,504],{},"The flue gas exiting the kiln carries entrained lime dust, captured in a downstream ",[68,501,503],{"href":502},"\u002Fglossary\u002Felectrostatic-precipitator","ESP"," before the stack. The ESP hopper handles fine lime, which bridges easily.",[79,506,508],{"id":507},"cleaning","Cleaning",[57,510,511,513],{},[68,512,129],{"href":128}," are installed at three points on a typical lime-kiln gas-cleaning train:",[136,515,516,522,528],{},[90,517,518,521],{},[60,519,520],{},"Lime-kiln preheater \u002F chain section"," — prevent mud-ring formation",[90,523,524,527],{},[60,525,526],{},"Lime-kiln ESP hopper"," — prevent fine-lime bridging",[90,529,530,533],{},[60,531,532],{},"Stack adjacency"," — if vent fouling becomes problematic",[79,535,134],{"id":133},[136,537,538,542,546,551],{},[90,539,540],{},[68,541,47],{"href":169},[90,543,544],{},[68,545,258],{"href":102},[90,547,548],{},[68,549,550],{"href":479},"Rotary kiln",[90,552,553],{},[68,554,444],{"href":128},{"title":159,"searchDepth":160,"depth":160,"links":556},[557,558,559,560],{"id":484,"depth":160,"text":485},{"id":495,"depth":160,"text":496},{"id":507,"depth":160,"text":508},{"id":133,"depth":160,"text":134},"A lime kiln at a kraft pulp mill calcines spent lime mud (CaCO₃) back to burnt lime (CaO) at ~1,200 °C for re-use in the recausticising chemical-recovery cycle. The kiln is a long inclined rotating cylinder, similar in form to a cement rotary kiln but smaller and lower-temperature.",{},[281,279,564,330],"rotary-kiln",{"title":566,"description":567},"Lime kiln — calcines lime mud back to burnt lime in the kraft chemical cycle","A lime kiln calcines spent lime mud back to burnt lime (CaO) for re-use in the kraft pulping chemical recovery cycle. Preheater chain section fouling is a recurring operational issue.",[569],{"title":570,"url":571},"Pulp & Paper Canada — TAPPI lime kiln guide","https:\u002F\u002Fwww.pulpandpapercanada.com\u002Ftappi-releases-lime-kiln-and-recausticizing-reference-guide\u002F","glossary\u002Flime-kiln","ORNW3CIwCuLywQAq2sTutCYomKMixgT2qQfcpkNkjI8",1782613748856]