[{"data":1,"prerenderedAt":848},["ShallowReactive",2],{"site-footer-common":3,"glossary:hot-side-esp-cold-side-esp":45,"glossary-related:hot-side-esp-cold-side-esp":222},{"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":203,"description":204,"extension":205,"meta":206,"navigation":207,"path":208,"relatedTerms":209,"seo":212,"sources":215,"stem":219,"term":220,"__hash__":221},"glossary\u002Fglossary\u002Fhot-side-esp-cold-side-esp.md","Hot-side ESP \u002F cold-side ESP",[49,50,51,52],"hot side ESP","cold side ESP","hot precipitator","cold precipitator",{"type":54,"value":55,"toc":196},"minimark",[56,79,143,148,151,155,168,172],[57,58,59,63,64,67,68,73,74,78],"p",{},[60,61,62],"strong",{},"Hot-side"," and ",[60,65,66],{},"cold-side"," describe where an ",[69,70,72],"a",{"href":71},"\u002Fglossary\u002Felectrostatic-precipitator","electrostatic precipitator"," sits in the flue-gas path relative to the boiler ",[69,75,77],{"href":76},"\u002Fglossary\u002Fair-heater","air heater",".",[80,81,82,101],"table",{},[83,84,85],"thead",{},[86,87,88,92,95,98],"tr",{},[89,90,91],"th",{},"Type",[89,93,94],{},"Position",[89,96,97],{},"Gas temperature",[89,99,100],{},"Why used",[102,103,104,129],"tbody",{},[86,105,106,110,113,116],{},[107,108,109],"td",{},"Hot-side ESP",[107,111,112],{},"Upstream of air heater",[107,114,115],{},"300–400 °C",[107,117,118,119,123,124,128],{},"Avoids high ash ",[69,120,122],{"href":121},"\u002Fglossary\u002Fresistivity","resistivity"," that causes ",[69,125,127],{"href":126},"\u002Fglossary\u002Fback-corona","back-corona"," on low-sulphur coals",[86,130,131,134,137,140],{},[107,132,133],{},"Cold-side ESP",[107,135,136],{},"Downstream of air heater",[107,138,139],{},"130–180 °C",[107,141,142],{},"Lower capital cost; standard for medium- and high-sulphur fuels",[144,145,147],"h2",{"id":146},"trade-offs","Trade-offs",[57,149,150],{},"Hot-side ESPs handle larger gas volumes (lower density at high temperature) and need bigger shells. They were popular in the 1970s–80s for Western US sub-bituminous and lignite coals. Most new installations are cold-side, often combined with flue-gas conditioning to manage resistivity.",[144,152,154],{"id":153},"cleaning-implications","Cleaning implications",[57,156,157,158,162,163,167],{},"Both designs benefit from acoustic cleaning. Hot-side ESPs need high-temperature horn materials such as ",[69,159,161],{"href":160},"\u002Fglossary\u002Finconel-625-718","Inconel 625 or 718","; cold-side ESPs can use ",[69,164,166],{"href":165},"\u002Fglossary\u002Faisi-316-316l-stainless","316 stainless"," but face cold-end corrosion risks if dew-point excursions occur.",[144,169,171],{"id":170},"related-terms","Related terms",[173,174,175,181,186,191],"ul",{},[176,177,178],"li",{},[69,179,180],{"href":71},"Electrostatic precipitator",[176,182,183],{},[69,184,185],{"href":121},"Resistivity (fly-ash)",[176,187,188],{},[69,189,190],{"href":126},"Back-corona",[176,192,193],{},[69,194,195],{"href":76},"Air heater",{"title":197,"searchDepth":198,"depth":198,"links":199},"",2,[200,201,202],{"id":146,"depth":198,"text":147},{"id":153,"depth":198,"text":154},{"id":170,"depth":198,"text":171},"esp","Hot-side and cold-side describe where an electrostatic precipitator sits in the flue-gas path relative to the boiler air heater.","md",{},true,"\u002Fglossary\u002Fhot-side-esp-cold-side-esp",[210,122,127,211],"electrostatic-precipitator","air-heater",{"title":213,"description":214},"Hot-side ESP vs cold-side ESP — where they sit in the gas path","A hot-side ESP is installed upstream of the air heater at 300–400 °C. A cold-side ESP sits downstream at 130–180 °C. The choice depends on ash resistivity and back-corona risk.",[216],{"title":217,"url":218},"EPA — Monitoring Knowledge Base: Electrostatic Precipitators","https:\u002F\u002Fwww.epa.gov\u002Fair-emissions-monitoring-knowledge-base\u002Fmonitoring-control-technique-electrostatic-precipitators","glossary\u002Fhot-side-esp-cold-side-esp","Hot-side and cold-side ESPs","Td7RBK0xN81CoINK0_swkR0JHhF33UsxSDhYe3ch7bk",[223,402,540,667],{"id":224,"title":225,"aliases":226,"body":230,"category":203,"description":379,"extension":205,"meta":380,"navigation":207,"path":71,"relatedTerms":381,"seo":389,"sources":392,"stem":400,"term":180,"__hash__":401},"glossary\u002Fglossary\u002Felectrostatic-precipitator.md","Electrostatic precipitator (ESP)",[227,228,229],"ESP","electrostatic precipitators","dry ESP",{"type":54,"value":231,"toc":373},[232,248,252,270,274,309,313,344,346],[57,233,234,235,238,239,243,244,247],{},"An ",[60,236,237],{},"electrostatic precipitator (ESP)"," is an air-pollution-control device that removes particulate matter from a flue-gas stream by electrostatically charging dust particles and collecting them on grounded plate electrodes. ESPs are the dominant particulate-control technology on coal-fired boilers, cement kilns, ",[69,240,242],{"href":241},"\u002Fglossary\u002Fwaste-to-energy","waste-to-energy"," plants, ",[69,245,246],{"href":241},"biomass"," plants, sinter strands and many other heavy-industry off-gas streams.",[144,249,251],{"id":250},"how-an-esp-works","How an ESP works",[57,253,254,255,259,260,264,265,269],{},"Flue gas flows horizontally between a parallel array of vertical ",[69,256,258],{"href":257},"\u002Fglossary\u002Fcollecting-electrode","collecting electrodes"," (plates) and ",[69,261,263],{"href":262},"\u002Fglossary\u002Fdischarge-electrode","discharge electrodes"," (high-voltage wires or rigid spikes). A negative DC potential of 40–80 kV applied to the discharge electrodes generates a ",[69,266,268],{"href":267},"\u002Fglossary\u002Fcorona-discharge","corona discharge"," that ionises the gas. Charged dust particles drift to the collecting plates, accumulate as a dust layer, are rapped down into hoppers below and removed by ash-handling equipment.",[144,271,273],{"id":272},"where-sonic-horns-fit","Where sonic horns fit",[57,275,276,277,281,282,286,287,291,292,296,297,299,300,304,305,78],{},"ESPs accumulate dust faster than mechanical rapping can release it, and hoppers below ESP fields routinely ",[69,278,280],{"href":279},"\u002Fglossary\u002Fbridging","bridge"," and choke. ",[69,283,285],{"href":284},"\u002Fglossary\u002Fsonic-horn","Sonic horns"," installed on the ESP ",[69,288,290],{"href":289},"\u002Fglossary\u002Fesp-penthouse","penthouse"," and on hopper walls keep dust dislodged, supplement ",[69,293,295],{"href":294},"\u002Fglossary\u002Fesp-rapper","rappers",", prevent ",[69,298,127],{"href":126}," by limiting plate dust thickness, and eliminate hopper ",[69,301,303],{"href":302},"\u002Fglossary\u002Frat-holing","rat-holing"," without the structural fatigue of ",[69,306,308],{"href":307},"\u002Fglossary\u002Ftumbling-hammer-rapper","tumbling-hammer rappers",[144,310,312],{"id":311},"common-failure-modes","Common failure modes",[173,314,315,321,326,332,338],{},[176,316,317,320],{},[60,318,319],{},"High opacity \u002F particulate emissions"," from thick dust layers reducing collection efficiency",[176,322,323,325],{},[60,324,190],{}," in high-resistivity ash that reverses ionisation and collapses collection",[176,327,328,331],{},[60,329,330],{},"Re-entrainment"," as rapper puffs return dust to the gas stream",[176,333,334,337],{},[60,335,336],{},"Hopper bridging"," that stops ash extraction and triggers field shutdowns",[176,339,340,343],{},[60,341,342],{},"Discharge-electrode breakage"," from rapper fatigue or sparking",[144,345,171],{"id":170},[173,347,348,353,358,362,368],{},[176,349,350],{},[69,351,352],{"href":257},"Collecting electrode",[176,354,355],{},[69,356,357],{"href":262},"Discharge electrode",[176,359,360],{},[69,361,190],{"href":126},[176,363,364],{},[69,365,367],{"href":366},"\u002Fglossary\u002Fesp-hopper","ESP hopper",[176,369,370],{},[69,371,372],{"href":284},"Sonic horn",{"title":197,"searchDepth":198,"depth":198,"links":374},[375,376,377,378],{"id":250,"depth":198,"text":251},{"id":272,"depth":198,"text":273},{"id":311,"depth":198,"text":312},{"id":170,"depth":198,"text":171},"An electrostatic precipitator (ESP) is an air-pollution-control device that removes particulate matter from a flue-gas stream by electrostatically charging dust particles and collecting them on grounded plate electrodes. ESPs are the dominant particulate-control technology on coal-fired boilers, cement kilns, waste-to-energy plants, biomass plants, sinter strands and many other heavy-industry off-gas streams.",{},[382,383,384,385,386,387,127,388],"wet-esp","collecting-electrode","discharge-electrode","corona-discharge","esp-hopper","esp-rapper","sonic-horn",{"title":390,"description":391},"Electrostatic precipitator (ESP) — how it works and how it fouls","An ESP removes particulate from flue gas by charging dust and collecting it on plate electrodes. Sonic horns are widely used to dislodge ash from plates and to keep hoppers from bridging.",[393,396,397],{"title":394,"url":395},"Wikipedia — Electrostatic precipitator","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FElectrostatic_precipitator",{"title":217,"url":218},{"title":398,"url":399},"Babcock & Wilcox — Basics of ESP Operation","https:\u002F\u002Fwww.babcock.com\u002Fhome\u002Fabout\u002Fresources\u002Flearning-center\u002Fbasic-esp-operation","glossary\u002Felectrostatic-precipitator","hT_C4hmid3iZaYWhLpiSJ2tBfL0bSJ-uhzn7TY4Vtj4",{"id":403,"title":185,"aliases":404,"body":408,"category":203,"description":530,"extension":205,"meta":531,"navigation":207,"path":121,"relatedTerms":532,"seo":533,"sources":536,"stem":538,"term":414,"__hash__":539},"glossary\u002Fglossary\u002Fresistivity.md",[405,406,407],"ash resistivity","fly ash resistivity","dust resistivity",{"type":54,"value":409,"toc":524},[410,424,428,474,478,492,496,503,505],[57,411,412,415,416,418,419,421,422,78],{},[60,413,414],{},"Fly-ash resistivity"," is the electrical resistance of the dust layer deposited on the ",[69,417,258],{"href":257}," of an ",[69,420,227],{"href":71},". It is the single most important fuel-dependent variable in ESP performance, because it controls whether the collected dust can discharge its acquired charge to ground or instead accumulates trapped charge that triggers ",[69,423,127],{"href":126},[144,425,427],{"id":426},"the-resistivity-window","The resistivity window",[80,429,430,440],{},[83,431,432],{},[86,433,434,437],{},[89,435,436],{},"Resistivity (Ω·cm)",[89,438,439],{},"ESP behaviour",[102,441,442,455,463],{},[86,443,444,447],{},[107,445,446],{},"Below 10⁸",[107,448,449,450,454],{},"Dust discharges too quickly; ",[69,451,453],{"href":452},"\u002Fglossary\u002Fre-entrainment","re-entrainment"," dominates",[86,456,457,460],{},[107,458,459],{},"10⁸–10¹¹",[107,461,462],{},"Ideal range; standard ESP operation",[86,464,465,468],{},[107,466,467],{},"Above 10¹¹",[107,469,470,471,473],{},"High risk of ",[69,472,127],{"href":126},"; collection efficiency collapses",[144,475,477],{"id":476},"what-raises-resistivity","What raises resistivity",[173,479,480,483,486,489],{},[176,481,482],{},"Low sulphur content in coal (less SO₃ to condition the ash)",[176,484,485],{},"Low gas temperature near the acid dew point",[176,487,488],{},"High-alkali biomass ash",[176,490,491],{},"Certain cement-kiln dust compositions",[144,493,495],{"id":494},"mitigation","Mitigation",[57,497,498,499,502],{},"The classic remedy is flue-gas conditioning — injecting SO₃ or ammonia ahead of the ESP to lower ash resistivity. A complementary remedy is to keep the plate dust layer thin enough that back-corona cannot establish, which is where ",[69,500,501],{"href":284},"sonic horns"," earn their keep on high-resistivity ESPs: continuous gentle dislodging prevents the critical thickness from developing.",[144,504,171],{"id":170},[173,506,507,511,515,520],{},[176,508,509],{},[69,510,180],{"href":71},[176,512,513],{},[69,514,190],{"href":126},[176,516,517],{},[69,518,519],{"href":267},"Corona discharge",[176,521,522],{},[69,523,372],{"href":284},{"title":197,"searchDepth":198,"depth":198,"links":525},[526,527,528,529],{"id":426,"depth":198,"text":427},{"id":476,"depth":198,"text":477},{"id":494,"depth":198,"text":495},{"id":170,"depth":198,"text":171},"Fly-ash resistivity is the electrical resistance of the dust layer deposited on the collecting electrodes of an ESP. It is the single most important fuel-dependent variable in ESP performance, because it controls whether the collected dust can discharge its acquired charge to ground or instead accumulates trapped charge that triggers back-corona.",{},[210,127,385,388],{"title":534,"description":535},"Fly-ash resistivity — why high-resistivity ash triggers ESP back-corona","Fly-ash resistivity is the electrical resistance of a deposited dust layer. Resistivity above ~10¹¹ Ω·cm triggers back-corona and degrades ESP performance.",[537],{"title":217,"url":218},"glossary\u002Fresistivity","J1-xKuznLqtCFjFw4yljyJW2c3Rl6O26UKlXuDzmDdo",{"id":541,"title":190,"aliases":542,"body":546,"category":203,"description":654,"extension":205,"meta":655,"navigation":207,"path":126,"relatedTerms":656,"seo":657,"sources":660,"stem":665,"term":190,"__hash__":666},"glossary\u002Fglossary\u002Fback-corona.md",[543,544,545],"reverse ionisation","back ionisation","back corona",{"type":54,"value":547,"toc":648},[548,563,567,573,593,597,614,618,624,626],[57,549,550,552,553,556,557,559,560,562],{},[60,551,190],{}," (also ",[554,555,543],"em",{},") is a destructive failure mode in an ",[69,558,72],{"href":71}," in which the dust layer on the ",[69,561,258],{"href":257}," accumulates so much charge that the gas trapped within it breaks down and emits ions of the opposite polarity. These positive ions discharge incoming negatively-charged dust particles before they reach the plate, and collection efficiency collapses.",[144,564,566],{"id":565},"when-back-corona-occurs","When back-corona occurs",[57,568,569,570,572],{},"Back-corona is triggered by high-",[69,571,122],{"href":121}," ash — typically above ~10¹¹ Ω·cm — combined with a thick, undisturbed dust layer. The conditions are common on:",[173,574,575,578,587,590],{},[176,576,577],{},"Low-sulphur Western US coals and sub-bituminous lignite",[176,579,580,581,63,583,586],{},"Some ",[69,582,246],{"href":241},[69,584,585],{"href":241},"WtE"," ashes",[176,588,589],{},"ESPs that have slipped behind on rapper maintenance",[176,591,592],{},"Cement-kiln ESPs after fuel switches or raw-mill stoppages",[144,594,596],{"id":595},"symptoms","Symptoms",[173,598,599,605,608,611],{},[176,600,601,602],{},"Falling secondary voltage at the ",[69,603,604],{"href":262},"discharge electrode",[176,606,607],{},"Rising secondary current with falling efficiency (the classic back-corona signature)",[176,609,610],{},"Persistent stack opacity rise that does not respond to rapper intensification",[176,612,613],{},"Sparking and arcing in the ESP power supply",[144,615,617],{"id":616},"sonic-horns-and-back-corona","Sonic horns and back-corona",[57,619,620,621,623],{},"Because back-corona is fundamentally a dust-thickness problem, the strongest mitigation is to keep the plates thinner — continuously, not in periodic bursts. ",[69,622,285],{"href":284}," installed across the field deliver gentle, frequent dislodging that holds the plate dust layer below the critical thickness for back-corona, while reducing the re-entrainment penalty of aggressive rapping. Acoustic cleaning is therefore one of the most cost-effective retrofits on a back-corona-limited ESP.",[144,625,171],{"id":170},[173,627,628,632,636,640,644],{},[176,629,630],{},[69,631,180],{"href":71},[176,633,634],{},[69,635,185],{"href":121},[176,637,638],{},[69,639,519],{"href":267},[176,641,642],{},[69,643,352],{"href":257},[176,645,646],{},[69,647,372],{"href":284},{"title":197,"searchDepth":198,"depth":198,"links":649},[650,651,652,653],{"id":565,"depth":198,"text":566},{"id":595,"depth":198,"text":596},{"id":616,"depth":198,"text":617},{"id":170,"depth":198,"text":171},"Back-corona (also reverse ionisation) is a destructive failure mode in an electrostatic precipitator in which the dust layer on the collecting electrodes accumulates so much charge that the gas trapped within it breaks down and emits ions of the opposite polarity. These positive ions discharge incoming negatively-charged dust particles before they reach the plate, and collection efficiency collapses.",{},[210,122,385,383,388],{"title":658,"description":659},"Back-corona — what it is, why it kills ESP performance, and how sonic horns help","Back-corona is reverse ionisation through a high-resistivity dust layer on ESP collecting plates. It collapses collection efficiency and is mitigated by keeping plates clean.",[661,664],{"title":662,"url":663},"Power Engineering — Tuning in to Acoustic Cleaning","https:\u002F\u002Fwww.power-eng.com\u002Fcoal\u002Ftuning-in-to-acoustic-cleaning\u002F",{"title":217,"url":218},"glossary\u002Fback-corona","G6FyEgaY8SP8-TTBfd1_Oq0GIZQSeNR8jVcFF2LPxto",{"id":668,"title":669,"aliases":670,"body":674,"category":831,"description":832,"extension":205,"meta":833,"navigation":207,"path":76,"relatedTerms":834,"seo":839,"sources":842,"stem":846,"term":195,"__hash__":847},"glossary\u002Fglossary\u002Fair-heater.md","Air heater (APH)",[671,672,673],"air preheater","APH","air heaters",{"type":54,"value":675,"toc":825},[676,689,693,736,740,751,781,785,791,793],[57,677,234,678,680,681,683,684,688],{},[60,679,77],{}," — also called an ",[60,682,671],{}," (APH) — is the final heat-recovery device in a boiler's ",[69,685,687],{"href":686},"\u002Fglossary\u002Fconvective-pass-backpass","convective pass",", recovering low-grade heat from cooling flue gas to preheat the combustion air. APHs lift overall boiler efficiency by 5–10 percentage points and are critical to heat-rate performance.",[144,690,692],{"id":691},"aph-types","APH types",[80,694,695,704],{},[83,696,697],{},[86,698,699,701],{},[89,700,91],{},[89,702,703],{},"Description",[102,705,706,717,728],{},[86,707,708,714],{},[107,709,710],{},[69,711,713],{"href":712},"\u002Fglossary\u002Fljungstrom-air-preheater","Ljungström \u002F regenerative",[107,715,716],{},"Rotating matrix of heat-exchange baskets cycling between gas and air sides",[86,718,719,725],{},[107,720,721],{},[69,722,724],{"href":723},"\u002Fglossary\u002Ftubular-air-preheater","Tubular",[107,726,727],{},"Fixed tube bundle with flue gas through tubes, air around them",[86,729,730,733],{},[107,731,732],{},"Plate-type",[107,734,735],{},"Cross-flow plate exchanger; smaller industrial duty",[144,737,739],{"id":738},"the-cold-end-problem","The cold-end problem",[57,741,742,743,745,746,750],{},"The APH cold end is the coolest point in the flue-gas path before the ",[69,744,227],{"href":71}," \u002F ",[69,747,749],{"href":748},"\u002Fglossary\u002Fbaghouse","baghouse",". Two related failure modes dominate:",[173,752,753,767],{},[176,754,755,761,762,766],{},[60,756,757],{},[69,758,760],{"href":759},"\u002Fglossary\u002Fammonium-bisulphate","Ammonium bisulphate (ABS)"," fouling on boilers with upstream ",[69,763,765],{"href":764},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR",": sticky deposits plug Ljungström baskets and tubular APH tubes",[176,768,769,775,776,780],{},[60,770,771],{},[69,772,774],{"href":773},"\u002Fglossary\u002Fcold-end-corrosion-dew-point-corrosion","Cold-end corrosion"," below the ",[69,777,779],{"href":778},"\u002Fglossary\u002Facid-dew-point","acid dew point"," — sulphuric acid condenses and attacks baskets and tubes",[144,782,784],{"id":783},"why-sonic-horns-are-routinely-specified-on-aphs","Why sonic horns are routinely specified on APHs",[57,786,787,788,790],{},"ABS fouling is the single most common reason plants install ",[69,789,501],{"href":284}," on the cold end. Continuous low-amplitude vibration prevents ABS from consolidating between water-wash campaigns, extending the campaign interval from quarterly to annual and avoiding capacity-derate excursions.",[144,792,171],{"id":170},[173,794,795,801,806,811,816,821],{},[176,796,797],{},[69,798,800],{"href":799},"\u002Fglossary\u002Fboiler","Boiler",[176,802,803],{},[69,804,805],{"href":712},"Ljungström air preheater",[176,807,808],{},[69,809,810],{"href":723},"Tubular air preheater",[176,812,813],{},[69,814,815],{"href":759},"Ammonium bisulphate",[176,817,818],{},[69,819,820],{"href":773},"Cold-end corrosion \u002F dew-point corrosion",[176,822,823],{},[69,824,372],{"href":284},{"title":197,"searchDepth":198,"depth":198,"links":826},[827,828,829,830],{"id":691,"depth":198,"text":692},{"id":738,"depth":198,"text":739},{"id":783,"depth":198,"text":784},{"id":170,"depth":198,"text":171},"boiler","An air heater — also called an air preheater (APH) — is the final heat-recovery device in a boiler's convective pass, recovering low-grade heat from cooling flue gas to preheat the combustion air. APHs lift overall boiler efficiency by 5–10 percentage points and are critical to heat-rate performance.",{},[831,835,836,837,838,388],"ljungstrom-air-preheater","tubular-air-preheater","ammonium-bisulphate","cold-end-corrosion-dew-point-corrosion",{"title":840,"description":841},"Air heater (APH) — final flue-gas heat-recovery device before the stack","An air heater (also air preheater, APH) recovers low-grade heat from flue gas to preheat combustion air. Cold-end fouling and corrosion are the dominant operational challenges.",[843],{"title":844,"url":845},"Wikipedia — Air preheater","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FAir_preheater","glossary\u002Fair-heater","3pBQ2ZyiQ7VOKuf9rxsx43EFarkhgykVhd2amXg0TMY",1782613735533]