[{"data":1,"prerenderedAt":716},["ShallowReactive",2],{"site-footer-common":3,"glossary:catalyst-poisoning":45,"glossary-related:catalyst-poisoning":220},{"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":201,"description":202,"extension":203,"meta":204,"navigation":205,"path":206,"relatedTerms":207,"seo":211,"sources":214,"stem":218,"term":47,"__hash__":219},"glossary\u002Fglossary\u002Fcatalyst-poisoning.md","Catalyst poisoning",[49,50],"SCR catalyst poisoning","catalyst deactivation",{"type":52,"value":53,"toc":194},"minimark",[54,77,82,150,154,174,178],[55,56,57,60,61,66,67,71,72,76],"p",{},[58,59,47],"strong",{}," is the chemical deactivation of ",[62,63,65],"a",{"href":64},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR catalyst"," active sites by trace species in the flue gas. Unlike ",[62,68,70],{"href":69},"\u002Fglossary\u002Fcatalyst-masking","masking"," (physical blanket) or ",[62,73,75],{"href":74},"\u002Fglossary\u002Fcatalyst-pluggage","pluggage"," (channel blockage), poisoning is a chemical process that binds molecules to the catalyst's vanadium, tungsten or titanium active centres. Cleaning cannot reverse it; the affected layer must be regenerated off-site or replaced.",[78,79,81],"h2",{"id":80},"common-poisons","Common poisons",[83,84,85,98],"table",{},[86,87,88],"thead",{},[89,90,91,95],"tr",{},[92,93,94],"th",{},"Poison",[92,96,97],{},"Source",[99,100,101,110,118,126,134,142],"tbody",{},[89,102,103,107],{},[104,105,106],"td",{},"Arsenic",[104,108,109],{},"Coal-fired flue gas, especially sub-bituminous",[89,111,112,115],{},[104,113,114],{},"Alkali metals (K, Na)",[104,116,117],{},"Biomass, agricultural-residue and waste-fuel ash",[89,119,120,123],{},[104,121,122],{},"Phosphorus",[104,124,125],{},"Animal-fat biofuels, sewage-sludge co-firing",[89,127,128,131],{},[104,129,130],{},"Calcium",[104,132,133],{},"Wet limestone scrubbers upstream, biomass",[89,135,136,139],{},[104,137,138],{},"Sulphur trioxide (high concentration)",[104,140,141],{},"SO₂ + V₂O₅ oxidation at high SCR temperature",[89,143,144,147],{},[104,145,146],{},"Lead and zinc",[104,148,149],{},"Waste-to-energy, some industrial off-gas streams",[78,151,153],{"id":152},"mitigation","Mitigation",[155,156,157,161,164,167],"ul",{},[158,159,160],"li",{},"Fuel selection \u002F blending to control fuel-bound poison content",[158,162,163],{},"Guard layers (sacrificial top catalyst layers protecting layers below)",[158,165,166],{},"Catalyst formulation tuned to expected poisons (e.g. alkali-resistant for biomass)",[158,168,169,173],{},[62,170,172],{"href":171},"\u002Fglossary\u002Fcatalyst-regeneration-vs-replacement","Catalyst regeneration vs replacement"," campaigns to extend catalyst life",[78,175,177],{"id":176},"related-terms","Related terms",[155,179,180,185,190],{},[158,181,182],{},[62,183,184],{"href":64},"Selective Catalytic Reduction (SCR)",[158,186,187],{},[62,188,189],{"href":69},"Catalyst masking",[158,191,192],{},[62,193,172],{"href":171},{"title":195,"searchDepth":196,"depth":196,"links":197},"",2,[198,199,200],{"id":80,"depth":196,"text":81},{"id":152,"depth":196,"text":153},{"id":176,"depth":196,"text":177},"scr-sncr","Catalyst poisoning is the chemical deactivation of SCR catalyst active sites by trace species in the flue gas. Unlike masking (physical blanket) or pluggage (channel blockage), poisoning is a chemical process that binds molecules to the catalyst's vanadium, tungsten or titanium active centres. Cleaning cannot reverse it; the affected layer must be regenerated off-site or replaced.","md",{},true,"\u002Fglossary\u002Fcatalyst-poisoning",[208,209,210],"selective-catalytic-reduction","catalyst-masking","catalyst-regeneration-vs-replacement",{"title":212,"description":213},"Catalyst poisoning — chemical deactivation of SCR active sites","Catalyst poisoning is the chemical binding of trace species (arsenic, alkali metals, phosphorus, sulphur) to SCR active sites. Usually irreversible — the catalyst layer must be replaced.",[215],{"title":216,"url":217},"Power Engineering — Selective Catalytic Reduction: Operational Issues","https:\u002F\u002Fwww.power-eng.com\u002Fenvironmental-emissions\u002Fselective-catalytic-reduction-operational-issues-and-guidelines\u002F","glossary\u002Fcatalyst-poisoning","bDfLprEkBdDowKQkBMNA0KvZrpMlXenCOlLhfqJMgdQ",[221,388,542],{"id":222,"title":184,"aliases":223,"body":227,"category":201,"description":365,"extension":203,"meta":366,"navigation":205,"path":64,"relatedTerms":367,"seo":375,"sources":378,"stem":385,"term":386,"__hash__":387},"glossary\u002Fglossary\u002Fselective-catalytic-reduction.md",[224,225,226],"SCR","SCR system","SCR reactor",{"type":52,"value":228,"toc":360},[229,248,252,268,272,275,302,320,322],[55,230,231,233,234,238,239,243,244,247],{},[58,232,184],{}," is the dominant flue-gas NOx-control technology on coal-fired and gas-fired utility boilers, ",[62,235,237],{"href":236},"\u002Fglossary\u002Fheat-recovery-steam-generator","HRSGs"," in combined-cycle plants, ",[62,240,242],{"href":241},"\u002Fglossary\u002Fwaste-to-energy","waste-to-energy"," and ",[62,245,246],{"href":241},"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.",[78,249,251],{"id":250},"reactor-layout","Reactor layout",[55,253,254,255,259,260,263,264,267],{},"A typical SCR reactor is a vertical or horizontal duct containing 2–4 layers of catalyst modules. Upstream of the catalyst sits the ",[62,256,258],{"href":257},"\u002Fglossary\u002Fammonia-injection-grid","ammonia injection grid (AIG)"," that distributes the ammonia evenly into the flue gas. Most installations operate in the ",[58,261,262],{},"high-dust"," position (between economiser and air heater) where catalyst temperature is around 300–400 °C; ",[58,265,266],{},"tail-end"," SCRs sit downstream of particulate control at lower temperatures, with the trade-off of needing flue-gas reheating.",[78,269,271],{"id":270},"fouling-and-cleaning","Fouling and cleaning",[55,273,274],{},"SCR catalysts foul in two ways:",[155,276,277,294],{},[158,278,279,284,285,243,289,293],{},[58,280,281],{},[62,282,283],{"href":74},"Pluggage"," — fly ash, ",[62,286,288],{"href":287},"\u002Fglossary\u002Fpopcorn-ash","popcorn ash",[62,290,292],{"href":291},"\u002Fglossary\u002Flarge-particle-ash","large-particle ash"," wedge into the catalyst cells, blocking the gas path",[158,295,296,301],{},[58,297,298],{},[62,299,300],{"href":69},"Masking"," — a thin layer of deposit covers the active sites; gas flow continues but catalytic activity falls",[55,303,304,305,309,310,314,315,319],{},"Both reduce NOx-reduction efficiency, raise ",[62,306,308],{"href":307},"\u002Fglossary\u002Fammonia-slip","ammonia slip",", and shorten catalyst life. Cleaning options include steam ",[62,311,313],{"href":312},"\u002Fglossary\u002Fsteam-sootblower","sootblowers",", ",[62,316,318],{"href":317},"\u002Fglossary\u002Fsonic-horn","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.",[78,321,177],{"id":176},[155,323,324,330,335,340,344,349,355],{},[158,325,326],{},[62,327,329],{"href":328},"\u002Fglossary\u002Fselective-non-catalytic-reduction","Selective Non-Catalytic Reduction (SNCR)",[158,331,332],{},[62,333,334],{"href":257},"Ammonia injection grid",[158,336,337],{},[62,338,339],{"href":307},"Ammonia slip",[158,341,342],{},[62,343,189],{"href":69},[158,345,346],{},[62,347,348],{"href":74},"Catalyst pluggage",[158,350,351],{},[62,352,354],{"href":353},"\u002Fglossary\u002Fhoneycomb-catalyst","Honeycomb catalyst",[158,356,357],{},[62,358,359],{"href":317},"Sonic horn",{"title":195,"searchDepth":196,"depth":196,"links":361},[362,363,364],{"id":250,"depth":196,"text":251},{"id":270,"depth":196,"text":271},{"id":176,"depth":196,"text":177},"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.",{},[368,369,370,371,209,372,373,374],"selective-non-catalytic-reduction","denox","ammonia-injection-grid","ammonia-slip","catalyst-pluggage","honeycomb-catalyst","sonic-horn",{"title":376,"description":377},"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.",[379,382],{"title":380,"url":381},"Wikipedia — Selective catalytic reduction","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSelective_catalytic_reduction",{"title":383,"url":384},"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":389,"title":189,"aliases":390,"body":394,"category":201,"description":528,"extension":203,"meta":529,"navigation":205,"path":69,"relatedTerms":530,"seo":532,"sources":535,"stem":540,"term":189,"__hash__":541},"glossary\u002Fglossary\u002Fcatalyst-masking.md",[391,392,393],"SCR catalyst masking","catalyst fouling","face plugging",{"type":52,"value":395,"toc":522},[396,404,408,462,465,469,483,487,498,500],[55,397,398,400,401,403],{},[58,399,189],{}," is the deposition of a thin blanket of fine ash on the face of an ",[62,402,65],{"href":64}," that physically blocks ammonia and NOx molecules from reaching the underlying active sites. Gas continues to flow through the catalyst cells, but the active surface area is shadowed and reaction efficiency falls.",[78,405,407],{"id":406},"how-masking-differs-from-related-failure-modes","How masking differs from related failure modes",[83,409,410,423],{},[86,411,412],{},[89,413,414,417,420],{},[92,415,416],{},"Failure mode",[92,418,419],{},"Mechanism",[92,421,422],{},"Reversible?",[99,424,425,437,449],{},[89,426,427,431,434],{},[104,428,429],{},[58,430,300],{},[104,432,433],{},"Ash blanket on the active surface",[104,435,436],{},"Yes — cleaning restores activity",[89,438,439,443,446],{},[104,440,441],{},[62,442,283],{"href":74},[104,444,445],{},"Particles physically block catalyst channels",[104,447,448],{},"Sometimes (depends on hardness)",[89,450,451,456,459],{},[104,452,453],{},[62,454,455],{"href":206},"Poisoning",[104,457,458],{},"Chemical species bind to active sites",[104,460,461],{},"Usually no — catalyst replacement",[55,463,464],{},"Masking is the most operationally manageable of the three because it responds to cleaning.",[78,466,468],{"id":467},"what-deposits-cause-masking","What deposits cause masking",[155,470,471,474,477,480],{},[158,472,473],{},"Calcium-rich fly ash (Western US sub-bituminous, biomass)",[158,475,476],{},"Ammonium-salt films on tail-end SCRs",[158,478,479],{},"Sub-micron silica from biomass fuels",[158,481,482],{},"Iron-oxide carry-over from blast-furnace or sinter-plant SCR applications",[78,484,486],{"id":485},"sonic-horns-and-masking-control","Sonic horns and masking control",[55,488,489,492,493,497],{},[62,490,491],{"href":317},"Sonic horns"," positioned upstream of each catalyst layer continuously dislodge the developing ash blanket before it consolidates. Combined with periodic steam ",[62,494,496],{"href":495},"\u002Fglossary\u002Fsonic-sootblower","sootblowing",", this two-tier cleaning typically restores catalyst activity by 10–30% within months of installation.",[78,499,177],{"id":176},[155,501,502,506,510,514,518],{},[158,503,504],{},[62,505,184],{"href":64},[158,507,508],{},[62,509,348],{"href":74},[158,511,512],{},[62,513,47],{"href":206},[158,515,516],{},[62,517,354],{"href":353},[158,519,520],{},[62,521,359],{"href":317},{"title":195,"searchDepth":196,"depth":196,"links":523},[524,525,526,527],{"id":406,"depth":196,"text":407},{"id":467,"depth":196,"text":468},{"id":485,"depth":196,"text":486},{"id":176,"depth":196,"text":177},"Catalyst masking is the deposition of a thin blanket of fine ash on the face of an SCR catalyst that physically blocks ammonia and NOx molecules from reaching the underlying active sites. Gas continues to flow through the catalyst cells, but the active surface area is shadowed and reaction efficiency falls.",{},[208,372,531,373,374],"catalyst-poisoning",{"title":533,"description":534},"Catalyst masking — fine-ash blanket that suppresses SCR activity","Catalyst masking is the deposition of a thin ash layer on the SCR catalyst face that blocks ammonia and NOx from reaching the active sites. Distinct from pluggage and poisoning.",[536,537],{"title":383,"url":384},{"title":538,"url":539},"Integrated Global Services — SCR Fouling Solved","https:\u002F\u002Fintegratedglobal.com\u002Fen\u002Fcase_studies\u002Fscr-performance\u002F","glossary\u002Fcatalyst-masking","WbNY355NxnwGZ3FW-bDAalSFTSrruJrjYN-62Fgc5Ig",{"id":543,"title":172,"aliases":544,"body":548,"category":201,"description":703,"extension":203,"meta":704,"navigation":205,"path":171,"relatedTerms":705,"seo":707,"sources":710,"stem":714,"term":172,"__hash__":715},"glossary\u002Fglossary\u002Fcatalyst-regeneration-vs-replacement.md",[545,546,547],"catalyst regeneration","SCR catalyst replacement","catalyst recycling",{"type":52,"value":549,"toc":697},[550,570,574,636,643,647,658,662,675,677],[55,551,552,555,556,558,559,562,563,565,566,569],{},[58,553,554],{},"Catalyst regeneration"," is the off-site process of removing accumulated ",[62,557,70],{"href":69}," deposits and reversing partial ",[62,560,561],{"href":206},"poisoning"," from used ",[62,564,65],{"href":64}," modules, restoring activity to 80–95% of fresh-catalyst performance. Major service providers (CORMETECH, MHPS \u002F Mitsubishi Power, STEAG \u002F SCR-Tech) operate dedicated facilities. ",[58,567,568],{},"Catalyst replacement"," is the alternative — install a fresh layer, discard or recycle the spent one.",[78,571,573],{"id":572},"economic-comparison","Economic comparison",[83,575,576,592],{},[86,577,578],{},[89,579,580,583,586,589],{},[92,581,582],{},"Option",[92,584,585],{},"Cost vs new (typical)",[92,587,588],{},"Performance recovery",[92,590,591],{},"Downtime",[99,593,594,608,622],{},[89,595,596,599,602,605],{},[104,597,598],{},"Regeneration",[104,600,601],{},"30–40% of new",[104,603,604],{},"80–95% of fresh activity",[104,606,607],{},"Few weeks (round-trip + change-out)",[89,609,610,613,616,619],{},[104,611,612],{},"Replacement (new)",[104,614,615],{},"100% reference",[104,617,618],{},"100%",[104,620,621],{},"Layer change-out only",[89,623,624,627,630,633],{},[104,625,626],{},"Skip change-out",[104,628,629],{},"0%",[104,631,632],{},"Continuing decay",[104,634,635],{},"None until permit excursion",[55,637,638,639,642],{},"For a large coal-fired or ",[62,640,641],{"href":241},"WtE"," SCR with 100–300 m³ of catalyst, regeneration typically saves USD 0.5–2 million per layer cycle.",[78,644,646],{"id":645},"where-regeneration-falls-short","Where regeneration falls short",[155,648,649,652,655],{},[158,650,651],{},"Severely poisoned catalyst (heavy arsenic, alkali, phosphorus) cannot be fully restored",[158,653,654],{},"Physical damage (broken modules, eroded channels) is not reversible",[158,656,657],{},"Layers that have already been regenerated twice tend not to support a third cycle",[78,659,661],{"id":660},"where-active-cleaning-fits","Where active cleaning fits",[55,663,664,666,667,669,670,674],{},[62,665,491],{"href":317}," and steam ",[62,668,496],{"href":495}," defer the need for ",[671,672,673],"em",{},"either"," regeneration or replacement by keeping masking under control during operation. A catalyst kept clean from the start lasts 30–50% longer before needing service.",[78,676,177],{"id":176},[155,678,679,683,687,691],{},[158,680,681],{},[62,682,184],{"href":64},[158,684,685],{},[62,686,47],{"href":206},[158,688,689],{},[62,690,189],{"href":69},[158,692,693],{},[62,694,696],{"href":695},"\u002Fglossary\u002Fcatalyst-layer-module","Catalyst layer \u002F module",{"title":195,"searchDepth":196,"depth":196,"links":698},[699,700,701,702],{"id":572,"depth":196,"text":573},{"id":645,"depth":196,"text":646},{"id":660,"depth":196,"text":661},{"id":176,"depth":196,"text":177},"Catalyst regeneration is the off-site process of removing accumulated masking deposits and reversing partial poisoning from used SCR catalyst modules, restoring activity to 80–95% of fresh-catalyst performance. Major service providers (CORMETECH, MHPS \u002F Mitsubishi Power, STEAG \u002F SCR-Tech) operate dedicated facilities. Catalyst replacement is the alternative — install a fresh layer, discard or recycle the spent one.",{},[208,531,209,706],"catalyst-layer-module",{"title":708,"description":709},"Catalyst regeneration vs replacement — defer the catalyst capex cycle","Regeneration removes accumulated masking and partial poisoning from used SCR catalyst, restoring activity to 90% of fresh and saving 60–70% of replacement cost.",[711],{"title":712,"url":713},"CORMETECH — SCR Catalyst Management Services","https:\u002F\u002Fwww.cormetech.com\u002Fonline-catalystcleaning\u002F","glossary\u002Fcatalyst-regeneration-vs-replacement","aA6xsWdxVur8-edCW8kWhJJp_fzCDOcmMkBIhRqHv8Q",1782613751075]