[{"data":1,"prerenderedAt":1001},["ShallowReactive",2],{"site-footer-common":3,"glossary:selective-non-catalytic-reduction":45,"glossary-related:selective-non-catalytic-reduction":204},{"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":51,"category":182,"description":183,"extension":184,"meta":185,"navigation":186,"path":187,"relatedTerms":188,"seo":194,"sources":197,"stem":201,"term":202,"__hash__":203},"glossary\u002Fglossary\u002Fselective-non-catalytic-reduction.md","Selective Non-Catalytic Reduction (SNCR)",[49,50],"SNCR","SNCR system",{"type":52,"value":53,"toc":175},"minimark",[54,72,77,105,109,112,135,142,146],[55,56,57,60,61,66,67,71],"p",{},[58,59,47],"strong",{}," reduces NOx in flue gas by injecting ammonia or aqueous urea directly into the furnace at high temperature (850–1100 °C), where the reagent reacts homogeneously with NOx without needing a catalyst. SNCR is cheaper to install than ",[62,63,65],"a",{"href":64},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR"," but achieves lower reduction (typically 30–60%) and produces higher ",[62,68,70],{"href":69},"\u002Fglossary\u002Fammonia-slip","ammonia slip",".",[73,74,76],"h2",{"id":75},"where-sncr-is-used","Where SNCR is used",[78,79,80,84,95,102],"ul",{},[81,82,83],"li",{},"Smaller industrial and utility boilers where SCR capital cost is unjustified",[81,85,86,90,91,94],{},[62,87,89],{"href":88},"\u002Fglossary\u002Fwaste-to-energy","Waste-to-energy"," and ",[62,92,93],{"href":88},"biomass"," plants — often as the primary DeNOx with optional SCR polish",[81,96,97,101],{},[62,98,100],{"href":99},"\u002Fglossary\u002Fpreheater-tower","Cement preheater towers"," where the gas temperature window is naturally available",[81,103,104],{},"As a retrofit on units where space prevents SCR installation",[73,106,108],{"id":107},"fouling-implications","Fouling implications",[55,110,111],{},"SNCR does not have a catalyst to foul, but the reagent injection itself creates downstream deposit risks:",[78,113,114,129],{},[81,115,116,119,120,124,125],{},[58,117,118],{},"Ammonia salt deposits"," — un-reacted ammonia combines with SO₃ and ash to form ",[62,121,123],{"href":122},"\u002Fglossary\u002Fammonium-bisulphate","ammonium bisulphate"," on cold-end heat-transfer surfaces, particularly the ",[62,126,128],{"href":127},"\u002Fglossary\u002Fair-heater","air heater",[81,130,131,134],{},[58,132,133],{},"Urea \u002F ammonia deposits on lance tips"," — injection lances can plug with urea solids or carbon deposits",[55,136,137,141],{},[62,138,140],{"href":139},"\u002Fglossary\u002Fsonic-horn","Sonic horns"," on the cold-end air heater address ABS fouling that follows SNCR operation.",[73,143,145],{"id":144},"related-terms","Related terms",[78,147,148,153,159,165,170],{},[81,149,150],{},[62,151,152],{"href":64},"Selective Catalytic Reduction (SCR)",[81,154,155],{},[62,156,158],{"href":157},"\u002Fglossary\u002Fdenox","DeNOx",[81,160,161],{},[62,162,164],{"href":163},"\u002Fglossary\u002Furea-sncr-aqueous-ammonia-sncr","Urea SNCR \u002F aqueous-ammonia SNCR",[81,166,167],{},[62,168,169],{"href":69},"Ammonia slip",[81,171,172],{},[62,173,174],{"href":122},"Ammonium bisulphate",{"title":176,"searchDepth":177,"depth":177,"links":178},"",2,[179,180,181],{"id":75,"depth":177,"text":76},{"id":107,"depth":177,"text":108},{"id":144,"depth":177,"text":145},"scr-sncr","Selective Non-Catalytic Reduction (SNCR) reduces NOx in flue gas by injecting ammonia or aqueous urea directly into the furnace at high temperature (850–1100 °C), where the reagent reacts homogeneously with NOx without needing a catalyst. SNCR is cheaper to install than SCR but achieves lower reduction (typically 30–60%) and produces higher ammonia slip.","md",{},true,"\u002Fglossary\u002Fselective-non-catalytic-reduction",[189,190,191,192,193],"selective-catalytic-reduction","denox","urea-sncr-aqueous-ammonia-sncr","ammonia-slip","ammonium-bisulphate",{"title":195,"description":196},"Selective Non-Catalytic Reduction (SNCR) — DeNOx without a catalyst","SNCR injects ammonia or urea directly into the furnace at 850–1100 °C to reduce NOx without a catalyst. Cheaper than SCR but lower efficiency and higher slip.",[198],{"title":199,"url":200},"Wikipedia — Selective non-catalytic reduction","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSelective_non-catalytic_reduction","glossary\u002Fselective-non-catalytic-reduction","Selective Non-Catalytic Reduction","IXdCJcIAQIaUzfIpBXuWLUA2b5T-pTWfhvZ703VsbdA",[205,364,546,710,844],{"id":206,"title":152,"aliases":207,"body":210,"category":182,"description":342,"extension":184,"meta":343,"navigation":186,"path":64,"relatedTerms":344,"seo":351,"sources":354,"stem":361,"term":362,"__hash__":363},"glossary\u002Fglossary\u002Fselective-catalytic-reduction.md",[65,208,209],"SCR system","SCR reactor",{"type":52,"value":211,"toc":337},[212,228,232,248,252,255,284,299,301],[55,213,214,216,217,221,222,90,225,227],{},[58,215,152],{}," is the dominant flue-gas NOx-control technology on coal-fired and gas-fired utility boilers, ",[62,218,220],{"href":219},"\u002Fglossary\u002Fheat-recovery-steam-generator","HRSGs"," in combined-cycle plants, ",[62,223,224],{"href":88},"waste-to-energy",[62,226,93],{"href":88}," boilers, cement plants and major refining furnaces. Ammonia or aqueous urea is injected upstream of a catalyst bed; the catalyst lowers the activation energy for the reaction NOx + NH₃ → N₂ + H₂O, achieving 80–95% NOx reduction across the reactor.",[73,229,231],{"id":230},"reactor-layout","Reactor layout",[55,233,234,235,239,240,243,244,247],{},"A typical SCR reactor is a vertical or horizontal duct containing 2–4 layers of catalyst modules. Upstream of the catalyst sits the ",[62,236,238],{"href":237},"\u002Fglossary\u002Fammonia-injection-grid","ammonia injection grid (AIG)"," that distributes the ammonia evenly into the flue gas. Most installations operate in the ",[58,241,242],{},"high-dust"," position (between economiser and air heater) where catalyst temperature is around 300–400 °C; ",[58,245,246],{},"tail-end"," SCRs sit downstream of particulate control at lower temperatures, with the trade-off of needing flue-gas reheating.",[73,249,251],{"id":250},"fouling-and-cleaning","Fouling and cleaning",[55,253,254],{},"SCR catalysts foul in two ways:",[78,256,257,275],{},[81,258,259,265,266,90,270,274],{},[58,260,261],{},[62,262,264],{"href":263},"\u002Fglossary\u002Fcatalyst-pluggage","Pluggage"," — fly ash, ",[62,267,269],{"href":268},"\u002Fglossary\u002Fpopcorn-ash","popcorn ash",[62,271,273],{"href":272},"\u002Fglossary\u002Flarge-particle-ash","large-particle ash"," wedge into the catalyst cells, blocking the gas path",[81,276,277,283],{},[58,278,279],{},[62,280,282],{"href":281},"\u002Fglossary\u002Fcatalyst-masking","Masking"," — a thin layer of deposit covers the active sites; gas flow continues but catalytic activity falls",[55,285,286,287,289,290,294,295,298],{},"Both reduce NOx-reduction efficiency, raise ",[62,288,70],{"href":69},", and shorten catalyst life. Cleaning options include steam ",[62,291,293],{"href":292},"\u002Fglossary\u002Fsteam-sootblower","sootblowers",", ",[62,296,297],{"href":139},"sonic horns"," and offline campaigns (vacuum \u002F water wash \u002F regeneration). Sonic horns are increasingly favoured because they continuously dislodge ash before it cements onto the catalyst face, without the steam erosion of mechanical sootblowing.",[73,300,145],{"id":144},[78,302,303,307,312,316,321,326,332],{},[81,304,305],{},[62,306,47],{"href":187},[81,308,309],{},[62,310,311],{"href":237},"Ammonia injection grid",[81,313,314],{},[62,315,169],{"href":69},[81,317,318],{},[62,319,320],{"href":281},"Catalyst masking",[81,322,323],{},[62,324,325],{"href":263},"Catalyst pluggage",[81,327,328],{},[62,329,331],{"href":330},"\u002Fglossary\u002Fhoneycomb-catalyst","Honeycomb catalyst",[81,333,334],{},[62,335,336],{"href":139},"Sonic horn",{"title":176,"searchDepth":177,"depth":177,"links":338},[339,340,341],{"id":230,"depth":177,"text":231},{"id":250,"depth":177,"text":251},{"id":144,"depth":177,"text":145},"Selective Catalytic Reduction (SCR) is the dominant flue-gas NOx-control technology on coal-fired and gas-fired utility boilers, HRSGs in combined-cycle plants, waste-to-energy and biomass boilers, cement plants and major refining furnaces. Ammonia or aqueous urea is injected upstream of a catalyst bed; the catalyst lowers the activation energy for the reaction NOx + NH₃ → N₂ + H₂O, achieving 80–95% NOx reduction across the reactor.",{},[345,190,346,192,347,348,349,350],"selective-non-catalytic-reduction","ammonia-injection-grid","catalyst-masking","catalyst-pluggage","honeycomb-catalyst","sonic-horn",{"title":352,"description":353},"Selective Catalytic Reduction (SCR) — how the dominant NOx-control technology works","SCR is the dominant NOx-control technology on industrial combustion plant. Ammonia is injected upstream of a catalyst that converts NOx to nitrogen and water.",[355,358],{"title":356,"url":357},"Wikipedia — Selective catalytic reduction","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSelective_catalytic_reduction",{"title":359,"url":360},"Power Engineering — SCR Catalyst Cleaning: Sootblowers vs. Acoustic Horns","https:\u002F\u002Fwww.power-eng.com\u002Foperations-maintenance\u002Fscr-catalyst-cleaningsootblowers-vs-acoustic-horns\u002F","glossary\u002Fselective-catalytic-reduction","Selective Catalytic Reduction","fmMCMd4NY3eZdSk_UYlbZ9ryi-9CR2Os6DivQjXEPCU",{"id":365,"title":158,"aliases":366,"body":370,"category":182,"description":533,"extension":184,"meta":534,"navigation":186,"path":157,"relatedTerms":535,"seo":537,"sources":540,"stem":544,"term":158,"__hash__":545},"glossary\u002Fglossary\u002Fdenox.md",[367,368,369],"deNOx","NOx reduction","NOx control",{"type":52,"value":371,"toc":528},[372,382,386,410,414,503,506,508],[55,373,374,376,377,90,379,381],{},[58,375,158],{}," is the collective term for post-combustion NOx-reduction technologies on industrial flue gas. The two dominant options are ",[62,378,152],{"href":64},[62,380,47],{"href":187},". Both rely on a reagent — ammonia or urea — that reacts with NOx to produce nitrogen and water.",[73,383,385],{"id":384},"why-denox-is-mandatory","Why DeNOx is mandatory",[55,387,388,389,294,393,294,397,294,401,405,406,409],{},"NOx is a regulated pollutant under the ",[62,390,392],{"href":391},"\u002Fglossary\u002Findustrial-emissions-directive","Industrial Emissions Directive (IED)",[62,394,396],{"href":395},"\u002Fglossary\u002Fmats-us-mercury-and-air-toxics","MATS",[62,398,400],{"href":399},"\u002Fglossary\u002Fepa-nsps","EPA NSPS",[62,402,404],{"href":403},"\u002Fglossary\u002Fta-luft-2021","TA Luft 2021"," and most national emission codes. Limits for coal-fired power stations and large ",[62,407,408],{"href":88},"WtE"," plants are usually 100–200 mg\u002FNm³ on a 30-day average, with stricter site-specific BAT-AEL values from BREF revisions.",[73,411,413],{"id":412},"choice-of-technology","Choice of technology",[415,416,417,433],"table",{},[418,419,420],"thead",{},[421,422,423,427,430],"tr",{},[424,425,426],"th",{},"Factor",[424,428,429],{},"Favours SCR",[424,431,432],{},"Favours SNCR",[434,435,436,448,459,470,481,492],"tbody",{},[421,437,438,442,445],{},[439,440,441],"td",{},"Reduction efficiency required",[439,443,444],{},"> 70%",[439,446,447],{},"30–60%",[421,449,450,453,456],{},[439,451,452],{},"Plant size",[439,454,455],{},"Large",[439,457,458],{},"Small \u002F medium",[421,460,461,464,467],{},[439,462,463],{},"Capital available",[439,465,466],{},"Higher",[439,468,469],{},"Lower",[421,471,472,475,478],{},[439,473,474],{},"Space available",[439,476,477],{},"More",[439,479,480],{},"Less",[421,482,483,486,489],{},[439,484,485],{},"Catalyst cost tolerance",[439,487,488],{},"Yes",[439,490,491],{},"Avoid",[421,493,494,497,500],{},[439,495,496],{},"Fuel chemistry",[439,498,499],{},"Predictable",[439,501,502],{},"Variable",[55,504,505],{},"Many plants run combined systems: SNCR provides bulk reduction, SCR polishes to meet permit limits.",[73,507,145],{"id":144},[78,509,510,514,518,524],{},[81,511,512],{},[62,513,152],{"href":64},[81,515,516],{},[62,517,47],{"href":187},[81,519,520],{},[62,521,523],{"href":522},"\u002Fglossary\u002Fnox-reduction-efficiency","NOx reduction efficiency",[81,525,526],{},[62,527,311],{"href":237},{"title":176,"searchDepth":177,"depth":177,"links":529},[530,531,532],{"id":384,"depth":177,"text":385},{"id":412,"depth":177,"text":413},{"id":144,"depth":177,"text":145},"DeNOx is the collective term for post-combustion NOx-reduction technologies on industrial flue gas. The two dominant options are Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). Both rely on a reagent — ammonia or urea — that reacts with NOx to produce nitrogen and water.",{},[189,345,536,346],"nox-reduction-efficiency",{"title":538,"description":539},"DeNOx — the family of post-combustion NOx-reduction technologies","DeNOx is the collective term for post-combustion NOx-reduction technologies. SCR and SNCR are the dominant options; both rely on reaction of NOx with ammonia or urea.",[541],{"title":542,"url":543},"Wikipedia — NOx","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FNOx","glossary\u002Fdenox","VgFeaJejynSvoxZt9xXRFXJSI6fE03o5ewbcMFuDDJA",{"id":547,"title":164,"aliases":548,"body":552,"category":182,"description":697,"extension":184,"meta":698,"navigation":186,"path":163,"relatedTerms":699,"seo":700,"sources":703,"stem":707,"term":708,"__hash__":709},"glossary\u002Fglossary\u002Furea-sncr-aqueous-ammonia-sncr.md",[549,550,551],"urea SNCR","aqueous ammonia SNCR","reagent choice SNCR",{"type":52,"value":553,"toc":692},[554,569,573,663,667,676,678],[55,555,556,560,561,564,565,568],{},[62,557,558],{"href":187},[58,559,49],{}," systems use one of two principal NOx-reducing reagents: ",[58,562,563],{},"urea"," (CO(NH₂)₂, usually delivered as 32–50% aqueous solution) or ",[58,566,567],{},"aqueous ammonia"," (NH₃ at 19–29% in water).",[73,570,572],{"id":571},"reagent-comparison","Reagent comparison",[415,574,575,588],{},[418,576,577],{},[421,578,579,582,585],{},[424,580,581],{},"Attribute",[424,583,584],{},"Urea",[424,586,587],{},"Aqueous ammonia",[434,589,590,601,612,621,632,641,652],{},[421,591,592,595,598],{},[439,593,594],{},"Storage hazard class",[439,596,597],{},"Non-hazardous",[439,599,600],{},"Toxic \u002F corrosive",[421,602,603,606,609],{},[439,604,605],{},"Required setback distance",[439,607,608],{},"Modest",[439,610,611],{},"Large (depends on jurisdiction)",[421,613,614,617,619],{},[439,615,616],{},"Permit complexity",[439,618,469],{},[439,620,466],{},[421,622,623,626,629],{},[439,624,625],{},"Reaction rate",[439,627,628],{},"Slower (decomposes first to NH₃)",[439,630,631],{},"Faster (direct NH₃)",[421,633,634,637,639],{},[439,635,636],{},"Reagent cost per kg-NO removed",[439,638,466],{},[439,640,469],{},[421,642,643,646,649],{},[439,644,645],{},"Suitability for cold furnaces",[439,647,648],{},"Good",[439,650,651],{},"Less good — vaporisation\u002Fdistribution issues",[421,653,654,657,660],{},[439,655,656],{},"Solid by-product risk",[439,658,659],{},"Urea solids at lance tips",[439,661,662],{},"None",[73,664,666],{"id":665},"selection-drivers","Selection drivers",[55,668,669,670,672,673,675],{},"Many plants choose urea for the permitting and safety advantages despite its higher reagent cost; large utilities with established ammonia handling tend towards aqueous ammonia for the lower OPEX. Both reagents produce the same ",[62,671,70],{"href":69}," and downstream ",[62,674,193],{"href":122}," consequences when slip is high.",[73,677,145],{"id":144},[78,679,680,684,688],{},[81,681,682],{},[62,683,47],{"href":187},[81,685,686],{},[62,687,169],{"href":69},[81,689,690],{},[62,691,174],{"href":122},{"title":176,"searchDepth":177,"depth":177,"links":693},[694,695,696],{"id":571,"depth":177,"text":572},{"id":665,"depth":177,"text":666},{"id":144,"depth":177,"text":145},"SNCR systems use one of two principal NOx-reducing reagents: urea (CO(NH₂)₂, usually delivered as 32–50% aqueous solution) or aqueous ammonia (NH₃ at 19–29% in water).",{},[345,192,193],{"title":701,"description":702},"Urea SNCR vs aqueous-ammonia SNCR — reagent choice for NOx reduction","SNCR systems use either solid urea (dissolved on site) or aqueous-ammonia solution as the NOx-reducing reagent. Urea is safer to store; aqueous ammonia is more reactive.",[704],{"title":705,"url":706},"Mehldau & Steinfath — SNCR Process for Coal-fired Boilers","https:\u002F\u002Fwww.ms-umwelt.de\u002Fwp-content\u002Fuploads\u002F2020\u002F08\u002F2013.06-PG-Europe__Vienna-SNCR-Process-for-Coal-Fired-Boilers-Experiences-and-Potential-for-the-Future.pdf","glossary\u002Furea-sncr-aqueous-ammonia-sncr","Urea SNCR and aqueous-ammonia SNCR","nnM_JfiERkVAReJLvNxC2rGAlhJF_Q2qHY2BF1w62bc",{"id":711,"title":169,"aliases":712,"body":715,"category":182,"description":832,"extension":184,"meta":833,"navigation":186,"path":69,"relatedTerms":834,"seo":835,"sources":838,"stem":842,"term":169,"__hash__":843},"glossary\u002Fglossary\u002Fammonia-slip.md",[713,714],"NH3 slip","ammonia breakthrough",{"type":52,"value":716,"toc":826},[717,728,732,770,774,789,793,802,804],[55,718,719,721,722,724,725,727],{},[58,720,169],{}," is the concentration of unreacted ammonia (NH₃) in the flue gas leaving an ",[62,723,65],{"href":64}," or ",[62,726,49],{"href":187}," system. It is the single most important operational KPI after NOx reduction itself: slip is regulated (typically capped at 2–10 ppm in permits), represents wasted reagent, and drives downstream fouling.",[73,729,731],{"id":730},"causes-of-high-ammonia-slip","Causes of high ammonia slip",[78,733,734,743,753,759,764],{},[81,735,736,739,740],{},[58,737,738],{},"Poor NH₃\u002FNOx mixing"," at the ",[62,741,742],{"href":237},"AIG",[81,744,745,724,749,752],{},[58,746,747],{},[62,748,320],{"href":281},[62,750,751],{"href":263},"pluggage"," reducing active surface area",[81,754,755,758],{},[58,756,757],{},"Catalyst age and de-activation"," towards end of life",[81,760,761],{},[58,762,763],{},"Operating temperature outside the catalyst window",[81,765,766,769],{},[58,767,768],{},"Over-injection of ammonia"," to compensate for falling NOx-reduction efficiency",[73,771,773],{"id":772},"downstream-consequences","Downstream consequences",[55,775,776,777,780,781,294,784,788],{},"Slipped ammonia combines with SO₃ in cooling flue gas to form ",[62,778,779],{"href":122},"ammonium bisulphate (ABS)",", a sticky low-melting deposit that fouls ",[62,782,783],{"href":127},"air heaters",[62,785,787],{"href":786},"\u002Fglossary\u002Feconomiser","economisers"," and downstream catalysts and filters. Excessive slip can therefore destroy the cold end of a boiler within months.",[73,790,792],{"id":791},"sonic-horns-and-slip-reduction","Sonic horns and slip reduction",[55,794,795,797,798,801],{},[62,796,140],{"href":139}," reduce slip indirectly by keeping the catalyst face clear of ",[62,799,800],{"href":281},"masking"," deposits, which preserves active surface area, which lets the catalyst convert ammonia to nitrogen instead of letting it slip. They also keep the AIG decks clean, preserving the designed spray pattern.",[73,803,145],{"id":144},[78,805,806,810,814,818,822],{},[81,807,808],{},[62,809,152],{"href":64},[81,811,812],{},[62,813,47],{"href":187},[81,815,816],{},[62,817,311],{"href":237},[81,819,820],{},[62,821,174],{"href":122},[81,823,824],{},[62,825,320],{"href":281},{"title":176,"searchDepth":177,"depth":177,"links":827},[828,829,830,831],{"id":730,"depth":177,"text":731},{"id":772,"depth":177,"text":773},{"id":791,"depth":177,"text":792},{"id":144,"depth":177,"text":145},"Ammonia slip is the concentration of unreacted ammonia (NH₃) in the flue gas leaving an SCR or SNCR system. It is the single most important operational KPI after NOx reduction itself: slip is regulated (typically capped at 2–10 ppm in permits), represents wasted reagent, and drives downstream fouling.",{},[189,345,346,193,347],{"title":836,"description":837},"Ammonia slip — unreacted NH3 leaving an SCR or SNCR system","Ammonia slip is unreacted ammonia leaving the DeNOx system in the flue gas. It is regulated, expensive in lost reagent, and causes ammonium-bisulphate fouling downstream.",[839],{"title":840,"url":841},"Power Engineering — Selective Catalytic Reduction: Operational Issues","https:\u002F\u002Fwww.power-eng.com\u002Fenvironmental-emissions\u002Fselective-catalytic-reduction-operational-issues-and-guidelines\u002F","glossary\u002Fammonia-slip","BU6p3qY3enI-T7Yz_rpYjEbWD0YUtLcL2fA38Y4iZN0",{"id":845,"title":846,"aliases":847,"body":852,"category":182,"description":987,"extension":184,"meta":988,"navigation":186,"path":122,"relatedTerms":989,"seo":992,"sources":995,"stem":999,"term":174,"__hash__":1000},"glossary\u002Fglossary\u002Fammonium-bisulphate.md","Ammonium bisulphate (ABS)",[848,849,850,851],"ABS","ammonium bisulfate","ammonium sulphate","NH4HSO4",{"type":52,"value":853,"toc":982},[854,873,877,880,916,920,956,958],[55,855,856,859,860,863,864,867,868,870,871,71],{},[58,857,858],{},"Ammonium bisulphate (NH₄HSO₄, ABS)"," — sometimes written ",[861,862,849],"em",{}," in US technical literature — is a sticky, low-melting deposit formed when ",[62,865,866],{"href":69},"slipped ammonia"," reacts with SO₃ in cooling flue gas. ABS condenses between roughly 150 °C and 250 °C, coating the cold end of any ",[62,869,128],{"href":127}," downstream of an ",[62,872,65],{"href":64},[73,874,876],{"id":875},"why-abs-is-the-most-feared-cold-end-deposit","Why ABS is the most-feared cold-end deposit",[55,878,879],{},"ABS is uniquely problematic because it is:",[78,881,882,888,898,904,910],{},[81,883,884,887],{},[58,885,886],{},"Sticky"," — bonds tenaciously to air-heater baskets and economiser tubes",[81,889,890,893,894],{},[58,891,892],{},"Hygroscopic"," — picks up moisture and accelerates ",[62,895,897],{"href":896},"\u002Fglossary\u002Fcold-end-corrosion-dew-point-corrosion","cold-end corrosion",[81,899,900,903],{},[58,901,902],{},"Hard to remove"," — resists steam sootblowing once consolidated",[81,905,906,909],{},[58,907,908],{},"Self-reinforcing"," — coated surfaces trap more ash, accelerating fouling",[81,911,912,915],{},[58,913,914],{},"Concentrated in a narrow temperature band"," — predictably plugs the same air-heater rows",[73,917,919],{"id":918},"mitigation","Mitigation",[78,921,922,930,936,942,950],{},[81,923,924,929],{},[58,925,926,927],{},"Minimise ",[62,928,70],{"href":69}," at the SCR (the single biggest lever)",[81,931,932,935],{},[58,933,934],{},"Manage SO₃ formation"," — fuel sulphur control, catalyst formulation",[81,937,938,941],{},[58,939,940],{},"Avoid the dew-point window"," — keep cold-end gas temperature above the formation band",[81,943,944,949],{},[58,945,946,948],{},[62,947,140],{"href":139}," on the cold end"," — continuous cleaning prevents ABS from consolidating before periodic water-washing",[81,951,952,955],{},[58,953,954],{},"Water-washing campaigns"," — periodic offline washes restore air-heater performance",[73,957,145],{"id":144},[78,959,960,964,968,973,978],{},[81,961,962],{},[62,963,169],{"href":69},[81,965,966],{},[62,967,152],{"href":64},[81,969,970],{},[62,971,972],{"href":127},"Air heater",[81,974,975],{},[62,976,977],{"href":896},"Cold-end corrosion \u002F dew-point corrosion",[81,979,980],{},[62,981,336],{"href":139},{"title":176,"searchDepth":177,"depth":177,"links":983},[984,985,986],{"id":875,"depth":177,"text":876},{"id":918,"depth":177,"text":919},{"id":144,"depth":177,"text":145},"Ammonium bisulphate (NH₄HSO₄, ABS) — sometimes written ammonium bisulfate in US technical literature — is a sticky, low-melting deposit formed when slipped ammonia reacts with SO₃ in cooling flue gas. ABS condenses between roughly 150 °C and 250 °C, coating the cold end of any air heater downstream of an SCR.",{},[192,189,990,991,350],"air-heater","cold-end-corrosion-dew-point-corrosion",{"title":993,"description":994},"Ammonium bisulphate (ABS) — sticky deposit from SCR slip plus SO3","Ammonium bisulphate is a sticky low-melting deposit formed when slipped ammonia reacts with SO3 in cooling flue gas. The dominant cold-end fouling species on SCR-equipped boilers.",[996],{"title":997,"url":998},"POWER Magazine — SO3's impacts on plant O&M","https:\u002F\u002Fwww.powermag.com\u002Fso3s-impacts-on-plant-om-part-ii\u002F","glossary\u002Fammonium-bisulphate","eVfkw0arMYLXvUn7Eb2ZquRKgct13PXCySe8Iclt3GY",1782613751818]