[{"data":1,"prerenderedAt":1331},["ShallowReactive",2],{"site-footer-common":3,"glossary:electrostatic-precipitator":45,"glossary-related:electrostatic-precipitator":246},{"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":52,"category":216,"description":217,"extension":218,"meta":219,"navigation":220,"path":221,"relatedTerms":222,"seo":230,"sources":233,"stem":243,"term":244,"__hash__":245},"glossary\u002Fglossary\u002Felectrostatic-precipitator.md","Electrostatic precipitator (ESP)",[49,50,51],"ESP","electrostatic precipitators","dry ESP",{"type":53,"value":54,"toc":208},"minimark",[55,74,79,97,101,139,143,177,181],[56,57,58,59,63,64,69,70,73],"p",{},"An ",[60,61,62],"strong",{},"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, ",[65,66,68],"a",{"href":67},"\u002Fglossary\u002Fwaste-to-energy","waste-to-energy"," plants, ",[65,71,72],{"href":67},"biomass"," plants, sinter strands and many other heavy-industry off-gas streams.",[75,76,78],"h2",{"id":77},"how-an-esp-works","How an ESP works",[56,80,81,82,86,87,91,92,96],{},"Flue gas flows horizontally between a parallel array of vertical ",[65,83,85],{"href":84},"\u002Fglossary\u002Fcollecting-electrode","collecting electrodes"," (plates) and ",[65,88,90],{"href":89},"\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 ",[65,93,95],{"href":94},"\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.",[75,98,100],{"id":99},"where-sonic-horns-fit","Where sonic horns fit",[56,102,103,104,108,109,113,114,118,119,123,124,128,129,133,134,138],{},"ESPs accumulate dust faster than mechanical rapping can release it, and hoppers below ESP fields routinely ",[65,105,107],{"href":106},"\u002Fglossary\u002Fbridging","bridge"," and choke. ",[65,110,112],{"href":111},"\u002Fglossary\u002Fsonic-horn","Sonic horns"," installed on the ESP ",[65,115,117],{"href":116},"\u002Fglossary\u002Fesp-penthouse","penthouse"," and on hopper walls keep dust dislodged, supplement ",[65,120,122],{"href":121},"\u002Fglossary\u002Fesp-rapper","rappers",", prevent ",[65,125,127],{"href":126},"\u002Fglossary\u002Fback-corona","back-corona"," by limiting plate dust thickness, and eliminate hopper ",[65,130,132],{"href":131},"\u002Fglossary\u002Frat-holing","rat-holing"," without the structural fatigue of ",[65,135,137],{"href":136},"\u002Fglossary\u002Ftumbling-hammer-rapper","tumbling-hammer rappers",".",[75,140,142],{"id":141},"common-failure-modes","Common failure modes",[144,145,146,153,159,165,171],"ul",{},[147,148,149,152],"li",{},[60,150,151],{},"High opacity \u002F particulate emissions"," from thick dust layers reducing collection efficiency",[147,154,155,158],{},[60,156,157],{},"Back-corona"," in high-resistivity ash that reverses ionisation and collapses collection",[147,160,161,164],{},[60,162,163],{},"Re-entrainment"," as rapper puffs return dust to the gas stream",[147,166,167,170],{},[60,168,169],{},"Hopper bridging"," that stops ash extraction and triggers field shutdowns",[147,172,173,176],{},[60,174,175],{},"Discharge-electrode breakage"," from rapper fatigue or sparking",[75,178,180],{"id":179},"related-terms","Related terms",[144,182,183,188,193,197,203],{},[147,184,185],{},[65,186,187],{"href":84},"Collecting electrode",[147,189,190],{},[65,191,192],{"href":89},"Discharge electrode",[147,194,195],{},[65,196,157],{"href":126},[147,198,199],{},[65,200,202],{"href":201},"\u002Fglossary\u002Fesp-hopper","ESP hopper",[147,204,205],{},[65,206,207],{"href":111},"Sonic horn",{"title":209,"searchDepth":210,"depth":210,"links":211},"",2,[212,213,214,215],{"id":77,"depth":210,"text":78},{"id":99,"depth":210,"text":100},{"id":141,"depth":210,"text":142},{"id":179,"depth":210,"text":180},"esp","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.","md",{},true,"\u002Fglossary\u002Felectrostatic-precipitator",[223,224,225,226,227,228,127,229],"wet-esp","collecting-electrode","discharge-electrode","corona-discharge","esp-hopper","esp-rapper","sonic-horn",{"title":231,"description":232},"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.",[234,237,240],{"title":235,"url":236},"Wikipedia — Electrostatic precipitator","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FElectrostatic_precipitator",{"title":238,"url":239},"EPA — Monitoring Knowledge Base: Electrostatic Precipitators","https:\u002F\u002Fwww.epa.gov\u002Fair-emissions-monitoring-knowledge-base\u002Fmonitoring-control-technique-electrostatic-precipitators",{"title":241,"url":242},"Babcock & Wilcox — Basics of ESP Operation","https:\u002F\u002Fwww.babcock.com\u002Fhome\u002Fabout\u002Fresources\u002Flearning-center\u002Fbasic-esp-operation","glossary\u002Felectrostatic-precipitator","Electrostatic precipitator","hT_C4hmid3iZaYWhLpiSJ2tBfL0bSJ-uhzn7TY4Vtj4",[247,336,441,539,644,775,979,1102],{"id":248,"title":249,"aliases":250,"body":254,"category":216,"description":322,"extension":218,"meta":323,"navigation":220,"path":324,"relatedTerms":325,"seo":328,"sources":331,"stem":333,"term":334,"__hash__":335},"glossary\u002Fglossary\u002Fwet-esp.md","Wet ESP (WESP)",[251,252,253],"WESP","wet electrostatic precipitator","wet ESPs",{"type":53,"value":255,"toc":317},[256,273,277,280,284,294,296],[56,257,258,259,262,263,265,266,269,270,272],{},"A ",[60,260,261],{},"wet electrostatic precipitator (WESP)"," is an ",[65,264,49],{"href":221}," in which the collecting surfaces are continuously washed with water rather than rapped dry. WESPs are specified where the particulate is sub-micron, sticky, hygroscopic or acidic — typically downstream of ",[65,267,268],{"href":221},"FGD scrubbers",", on ",[65,271,72],{"href":67}," and waste-to-energy plants, in coke-oven flue paths and on certain refinery and metals off-gas streams.",[75,274,276],{"id":275},"tube-type-vs-plate-type-wesps","Tube-type vs plate-type WESPs",[56,278,279],{},"Most WESPs are tube-type, with vertical cylindrical collectors and a coaxial discharge electrode in each tube. Plate-type WESPs also exist for retrofit duty into existing dry-ESP shells. Water sluicing is either continuous, intermittent flushing, or condensate-driven.",[75,281,283],{"id":282},"where-sonic-horns-help","Where sonic horns help",[56,285,286,287,290,291,293],{},"The wash-water film usually keeps the collecting surfaces clean, but solids accumulate in the ",[60,288,289],{},"sumps and dust-handling hoppers below the WESP",". ",[65,292,112],{"href":111}," prevent sludge bridging and pluggage in these low-level hoppers and pipework, where conventional rapping is impractical and manual cleaning is hazardous.",[75,295,180],{"id":179},[144,297,298,302,308,313],{},[147,299,300],{},[65,301,244],{"href":221},[147,303,304],{},[65,305,307],{"href":306},"\u002Fglossary\u002Fplate-type-esp-tube-type-esp","Plate-type ESP \u002F tube-type ESP",[147,309,310],{},[65,311,312],{"href":94},"Corona discharge",[147,314,315],{},[65,316,207],{"href":111},{"title":209,"searchDepth":210,"depth":210,"links":318},[319,320,321],{"id":275,"depth":210,"text":276},{"id":282,"depth":210,"text":283},{"id":179,"depth":210,"text":180},"A wet electrostatic precipitator (WESP) is an ESP in which the collecting surfaces are continuously washed with water rather than rapped dry. WESPs are specified where the particulate is sub-micron, sticky, hygroscopic or acidic — typically downstream of FGD scrubbers, on biomass and waste-to-energy plants, in coke-oven flue paths and on certain refinery and metals off-gas streams.",{},"\u002Fglossary\u002Fwet-esp",[326,327,226,229],"electrostatic-precipitator","plate-type-esp-tube-type-esp",{"title":329,"description":330},"Wet ESP (WESP) — definition, applications and cleaning issues","A wet electrostatic precipitator continuously washes its collecting surfaces with water, used for sub-micron particulate, acid mist and sticky aerosols downstream of FGD or biomass scrubbers.",[332],{"title":235,"url":236},"glossary\u002Fwet-esp","Wet electrostatic precipitator","y9WXPV9UgI-euyX7Gvtpd4HQjiXQ-8yMrDGvpZkJcgM",{"id":337,"title":187,"aliases":338,"body":342,"category":216,"description":431,"extension":218,"meta":432,"navigation":220,"path":84,"relatedTerms":433,"seo":434,"sources":437,"stem":439,"term":187,"__hash__":440},"glossary\u002Fglossary\u002Fcollecting-electrode.md",[339,340,341],"collecting plate","collection plate","ESP plate",{"type":53,"value":343,"toc":425},[344,355,359,381,385,393,397,400,402],[56,345,346,347,350,351,354],{},"The ",[60,348,349],{},"collecting electrode"," — usually called the \"collecting plate\" in plate-type ESPs — is the grounded surface on which charged particulate accumulates inside an ",[65,352,353],{"href":221},"electrostatic precipitator",". Collecting plates are typically 9–15 m tall, rolled or profiled steel sections with stiffening pockets, hung in parallel rows 250–400 mm apart.",[75,356,358],{"id":357},"how-dust-accumulates-and-releases","How dust accumulates and releases",[56,360,361,362,365,366,368,369,372,373,376,377,380],{},"Charged particles migrate from the ",[65,363,364],{"href":89},"discharge electrode"," towards the grounded plate, transfer their charge and adhere as a dust layer. The layer must be released regularly: too thick and it raises plate-face voltage, reducing the field, eventually triggering ",[65,367,127],{"href":126},". Release is achieved by ",[65,370,371],{"href":121},"rapping"," (mechanical impact) or ",[65,374,375],{"href":111},"sonic horns"," (acoustic vibration), with the released dust sheet falling into the ",[65,378,379],{"href":201},"hopper"," below.",[75,382,384],{"id":383},"the-re-entrainment-problem","The re-entrainment problem",[56,386,387,388,392],{},"Aggressive rapping releases dust faster than the hopper can swallow it, and some of the falling sheet is caught back up by the gas stream — this is ",[65,389,391],{"href":390},"\u002Fglossary\u002Fre-entrainment","re-entrainment",", and it shows up as periodic opacity spikes on stack CEMS traces. Sonic horns produce gentler, more continuous release that reduces re-entrainment compared to mechanical rapping alone.",[75,394,396],{"id":395},"profile-types","Profile types",[56,398,399],{},"Collecting plates come in many profiled forms (CW, ZT, ECO, Opzel, baffle, etc.), each chosen to balance electrical performance against dust-release behaviour. Specialist ESP vendors (B&W, FLSmidth, Hamon, Mitsubishi) supply matched plate-and-rapping packages.",[75,401,180],{"id":179},[144,403,404,408,412,417,421],{},[147,405,406],{},[65,407,244],{"href":221},[147,409,410],{},[65,411,192],{"href":89},[147,413,414],{},[65,415,416],{"href":121},"ESP rapper",[147,418,419],{},[65,420,207],{"href":111},[147,422,423],{},[65,424,163],{"href":390},{"title":209,"searchDepth":210,"depth":210,"links":426},[427,428,429,430],{"id":357,"depth":210,"text":358},{"id":383,"depth":210,"text":384},{"id":395,"depth":210,"text":396},{"id":179,"depth":210,"text":180},"The collecting electrode — usually called the \"collecting plate\" in plate-type ESPs — is the grounded surface on which charged particulate accumulates inside an electrostatic precipitator. Collecting plates are typically 9–15 m tall, rolled or profiled steel sections with stiffening pockets, hung in parallel rows 250–400 mm apart.",{},[326,225,228,229,391],{"title":435,"description":436},"Collecting electrode (ESP plate) — function, fouling and cleaning","The collecting electrode is the grounded plate or tube on which charged particulate accumulates inside an ESP. Dust must be released to hoppers without re-entraining into the gas stream.",[438],{"title":241,"url":242},"glossary\u002Fcollecting-electrode","9E4jLiOYVWf0Kj-hlJN58FMZ0Nz2mF0Iv1OuBtFwtqM",{"id":442,"title":192,"aliases":443,"body":448,"category":216,"description":529,"extension":218,"meta":530,"navigation":220,"path":89,"relatedTerms":531,"seo":532,"sources":535,"stem":537,"term":192,"__hash__":538},"glossary\u002Fglossary\u002Fdischarge-electrode.md",[444,445,446,447],"emitting electrode","corona electrode","discharge wire","rigid discharge electrode",{"type":53,"value":449,"toc":524},[450,466,470,473,490,494,500,502],[56,451,346,452,454,455,457,458,460,461,463,464,138],{},[60,453,364],{}," (also called the ",[60,456,444],{},") is the high-voltage element inside an ",[65,459,353],{"href":221}," that generates the ",[65,462,95],{"href":94},". It is energised at 40–80 kV DC negative relative to the grounded ",[65,465,85],{"href":84},[75,467,469],{"id":468},"geometry","Geometry",[56,471,472],{},"Two families dominate:",[144,474,475,484],{},[147,476,477,480,481,483],{},[60,478,479],{},"Wire electrodes"," — fine spiral or barbed wires, typically weighted at the bottom and suspended from a top frame. Lightweight; easy to retrofit; prone to fatigue and breakage under ",[65,482,371],{"href":121}," impacts.",[147,485,486,489],{},[60,487,488],{},"Rigid discharge electrodes (RDE)"," — pipe or mast sections with formed spikes or points. Used in modern American-style and rigid-frame ESPs. More robust against rapper breakage but heavier.",[75,491,493],{"id":492},"fouling-on-discharge-electrodes","Fouling on discharge electrodes",[56,495,496,497,499],{},"Just like the collecting plates, discharge electrodes accumulate dust. A thick coating on a wire or RDE reduces the local field gradient, suppresses corona, and lowers collection efficiency. The cleaning challenge is geometrically harder than for plates — discharge electrodes are point or line sources surrounded by gas. ",[65,498,112],{"href":111}," addressing the whole field volume help dislodge dust from discharge electrodes as well as from plates.",[75,501,180],{"id":179},[144,503,504,508,512,516,520],{},[147,505,506],{},[65,507,244],{"href":221},[147,509,510],{},[65,511,187],{"href":84},[147,513,514],{},[65,515,312],{"href":94},[147,517,518],{},[65,519,157],{"href":126},[147,521,522],{},[65,523,207],{"href":111},{"title":209,"searchDepth":210,"depth":210,"links":525},[526,527,528],{"id":468,"depth":210,"text":469},{"id":492,"depth":210,"text":493},{"id":179,"depth":210,"text":180},"The discharge electrode (also called the emitting electrode) is the high-voltage element inside an electrostatic precipitator that generates the corona discharge. It is energised at 40–80 kV DC negative relative to the grounded collecting electrodes.",{},[326,224,226,127,229],{"title":533,"description":534},"Discharge electrode — the high-voltage emitter inside an ESP","The discharge electrode is the high-voltage electrode that generates the corona discharge inside an ESP. Charged dust drifts from it to the collecting plates.",[536],{"title":235,"url":236},"glossary\u002Fdischarge-electrode","E8VJGt3XxJD7K99lsPd9v-FQlmpjndXP4FYfB-pqPJk",{"id":540,"title":312,"aliases":541,"body":544,"category":216,"description":632,"extension":218,"meta":633,"navigation":220,"path":94,"relatedTerms":634,"seo":635,"sources":638,"stem":642,"term":312,"__hash__":643},"glossary\u002Fglossary\u002Fcorona-discharge.md",[542,543],"corona (electrical)","negative corona",{"type":53,"value":545,"toc":627},[546,560,564,567,571,603,606,608],[56,547,258,548,550,551,553,554,556,557,559],{},[60,549,95],{}," is a self-sustaining electrical discharge that occurs when the field gradient around a sharp electrode exceeds the breakdown threshold of the surrounding gas. In an ",[65,552,49],{"href":221}," the corona forms around the ",[65,555,364],{"href":89},", ionises flue-gas molecules, and the resulting ions attach to dust particles. The charged particles then drift to the ",[65,558,85],{"href":84}," under the electric field.",[75,561,563],{"id":562},"negative-corona-dominates","Negative corona dominates",[56,565,566],{},"Industrial ESPs almost always run on negative corona because it sustains a higher voltage before sparking — but it also produces some ozone, which is one of the reasons WESPs in confined ventilation paths sometimes use positive corona instead.",[75,568,570],{"id":569},"what-disrupts-the-corona","What disrupts the corona",[144,572,573,579,591,597],{},[147,574,575,578],{},[60,576,577],{},"Excessive dust on the collecting plate"," — raises plate-face voltage, narrows the working gap",[147,580,581,588,589],{},[60,582,583,584],{},"High ash ",[65,585,587],{"href":586},"\u002Fglossary\u002Fresistivity","resistivity"," — traps charge in the dust layer, leading to ",[65,590,127],{"href":126},[147,592,593,596],{},[60,594,595],{},"Bent or broken discharge electrodes"," — local field collapse, sparking, eventual short",[147,598,599,602],{},[60,600,601],{},"Fouled discharge electrode tips"," — suppressed corona, reduced ion current",[56,604,605],{},"Acoustic cleaning addresses two of these (plate dust thickness and discharge-electrode fouling) without the broken-electrode risk of aggressive mechanical rapping.",[75,607,180],{"id":179},[144,609,610,614,618,622],{},[147,611,612],{},[65,613,244],{"href":221},[147,615,616],{},[65,617,192],{"href":89},[147,619,620],{},[65,621,157],{"href":126},[147,623,624],{},[65,625,626],{"href":586},"Resistivity (fly-ash)",{"title":209,"searchDepth":210,"depth":210,"links":628},[629,630,631],{"id":562,"depth":210,"text":563},{"id":569,"depth":210,"text":570},{"id":179,"depth":210,"text":180},"A corona discharge is a self-sustaining electrical discharge that occurs when the field gradient around a sharp electrode exceeds the breakdown threshold of the surrounding gas. In an ESP the corona forms around the discharge electrode, ionises flue-gas molecules, and the resulting ions attach to dust particles. The charged particles then drift to the collecting electrodes under the electric field.",{},[326,225,127,587],{"title":636,"description":637},"Corona discharge — the ionisation mechanism that powers an ESP","Corona discharge is the electrical breakdown around an ESP's discharge electrode that ionises gas molecules and charges dust particles for collection.",[639],{"title":640,"url":641},"Wikipedia — Corona discharge","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FCorona_discharge","glossary\u002Fcorona-discharge","dShpP0lym_kkFMbohrkUgv75_uA0O8qlKu9VJ1eimyA",{"id":645,"title":202,"aliases":646,"body":650,"category":216,"description":761,"extension":218,"meta":762,"navigation":220,"path":201,"relatedTerms":763,"seo":766,"sources":769,"stem":773,"term":202,"__hash__":774},"glossary\u002Fglossary\u002Fesp-hopper.md",[647,648,649],"ESP ash hopper","precipitator hopper","dust hopper",{"type":53,"value":651,"toc":756},[652,663,667,705,708,712,724,726],[56,653,58,654,656,657,659,660,662],{},[60,655,202],{}," is the inverted-pyramid (or trough) vessel below each ",[65,658,49],{"href":221}," field that collects ash dislodged from the ",[65,661,85],{"href":84},". Ash falls into the hopper and is extracted by pneumatic, drag-chain or hydraulic conveyors. ESP hoppers are one of the most chronic failure points in a coal, biomass, WtE or cement-plant flue-gas train.",[75,664,666],{"id":665},"why-esp-hoppers-fail","Why ESP hoppers fail",[144,668,669,677,685,691,699],{},[147,670,671,676],{},[60,672,673],{},[65,674,675],{"href":106},"Bridging"," — the ash forms a stable arch across the narrowing hopper, stopping discharge.",[147,678,679,684],{},[60,680,681],{},[65,682,683],{"href":131},"Rat-holing"," — a narrow channel forms above the outlet and the surrounding mass packs and hardens.",[147,686,687,690],{},[60,688,689],{},"Sneakage"," — gas short-circuits through hopper voids when extraction stops.",[147,692,693,696,697,138],{},[60,694,695],{},"Pluggage"," — full hoppers back ash up into the field, raising plate-face voltage and triggering ",[65,698,127],{"href":126},[147,700,701,704],{},[60,702,703],{},"Failed level switches"," that mask developing pluggage from operators.",[56,706,707],{},"Once an ESP hopper plugs, the affected field must be taken offline; full-load operation may not be possible while the hopper is cleaned by vacuum truck or manual lancing. A single hopper-cleaning outage can cost hundreds of MWh in lost generation.",[75,709,711],{"id":710},"sonic-horns-on-esp-hoppers","Sonic horns on ESP hoppers",[56,713,714,715,718,719,723],{},"A 60–125 Hz ",[65,716,717],{"href":111},"sonic horn"," mounted at the hopper wall is the standard mitigation. The horn fires every few minutes during normal operation, keeping the ash mobile and preventing the cohesive structures that lead to bridging and rat-holing. Acoustic horns are particularly favoured over ",[65,720,722],{"href":721},"\u002Fglossary\u002Fair-cannon-air-blaster","air cannons"," here because they cause no impact stress on the hopper structure, no fatigue on weld joints, and can be installed during a routine outage rather than a major shutdown.",[75,725,180],{"id":179},[144,727,728,732,738,742,746,752],{},[147,729,730],{},[65,731,244],{"href":221},[147,733,734],{},[65,735,737],{"href":736},"\u002Fglossary\u002Fhopper","Hopper",[147,739,740],{},[65,741,675],{"href":106},[147,743,744],{},[65,745,683],{"href":131},[147,747,748],{},[65,749,751],{"href":750},"\u002Fglossary\u002Ffly-ash-hopper","Fly-ash hopper",[147,753,754],{},[65,755,207],{"href":111},{"title":209,"searchDepth":210,"depth":210,"links":757},[758,759,760],{"id":665,"depth":210,"text":666},{"id":710,"depth":210,"text":711},{"id":179,"depth":210,"text":180},"An ESP hopper is the inverted-pyramid (or trough) vessel below each ESP field that collects ash dislodged from the collecting electrodes. Ash falls into the hopper and is extracted by pneumatic, drag-chain or hydraulic conveyors. ESP hoppers are one of the most chronic failure points in a coal, biomass, WtE or cement-plant flue-gas train.",{},[326,379,764,132,765,229],"bridging","fly-ash-hopper",{"title":767,"description":768},"ESP hopper — bridging, pluggage and sonic-horn de-bridging","An ESP hopper is the inverted-pyramid vessel below each ESP field that collects rapped-down fly ash. Bridging and rat-holing are common failures; sonic horns are the standard mitigation.",[770],{"title":771,"url":772},"Power Engineering — Tuning in to Acoustic Cleaning","https:\u002F\u002Fwww.power-eng.com\u002Fcoal\u002Ftuning-in-to-acoustic-cleaning\u002F","glossary\u002Fesp-hopper","ahXWkBIudy7ZPXa82rBmYAWPJ32yu6Pvp9wqbeOrGtU",{"id":776,"title":416,"aliases":777,"body":781,"category":216,"description":964,"extension":218,"meta":965,"navigation":220,"path":121,"relatedTerms":966,"seo":969,"sources":972,"stem":977,"term":416,"__hash__":978},"glossary\u002Fglossary\u002Fesp-rapper.md",[778,779,780],"rapper","collecting plate rapper","discharge electrode rapper",{"type":53,"value":782,"toc":959},[783,806,810,824,828,922,929,931],[56,784,58,785,787,788,791,792,794,795,797,798,800,801,805],{},[60,786,416],{}," is a mechanical device used to dislodge accumulated dust from the ",[65,789,790],{"href":84},"collecting"," and ",[65,793,90],{"href":89}," of an ",[65,796,353],{"href":221},". Two principal designs dominate: ",[65,799,137],{"href":136},", favoured in European-style ESPs, and ",[65,802,804],{"href":803},"\u002Fglossary\u002Fmagnetic-impulse-gravity-rapper","magnetic-impulse-gravity (MIGI) rappers",", favoured in American-style ESPs.",[75,807,809],{"id":808},"how-rapping-is-sequenced","How rapping is sequenced",[56,811,812,813,815,816,820,821,823],{},"Rappers are fired in a programmed sequence — usually one rapper at a time per field — to avoid simultaneous releases that would overwhelm the ",[65,814,379],{"href":201},". The interval depends on dust load: every few minutes on heavily-loaded inlet fields, every 20–60 minutes on lightly-loaded outlet fields. Tuning the rap interval is a perennial trade-off between low ",[65,817,819],{"href":818},"\u002Fglossary\u002Fopacity","opacity"," (frequent rapping) and high ",[65,822,391],{"href":390}," (also frequent rapping).",[75,825,827],{"id":826},"sonic-horns-vs-rappers","Sonic horns vs rappers",[829,830,831,847],"table",{},[832,833,834],"thead",{},[835,836,837,841,843],"tr",{},[838,839,840],"th",{},"Attribute",[838,842,416],{},[838,844,845],{},[65,846,207],{"href":111},[848,849,850,862,873,884,900,911],"tbody",{},[835,851,852,856,859],{},[853,854,855],"td",{},"Mechanism",[853,857,858],{},"Mechanical impact",[853,860,861],{},"Acoustic vibration",[835,863,864,867,870],{},[853,865,866],{},"Release pattern",[853,868,869],{},"Large, periodic",[853,871,872],{},"Small, frequent",[835,874,875,878,881],{},[853,876,877],{},"Re-entrainment risk",[853,879,880],{},"High",[853,882,883],{},"Low",[835,885,886,889,892],{},[853,887,888],{},"Hopper coverage",[853,890,891],{},"Plates only",[853,893,894,895,899],{},"Plates ",[896,897,898],"em",{},"and"," hoppers",[835,901,902,905,908],{},[853,903,904],{},"Wear \u002F fatigue",[853,906,907],{},"Discharge-electrode breakage, hammer-shaft failure",[853,909,910],{},"Diaphragm replacement every 3–5 years",[835,912,913,916,919],{},[853,914,915],{},"Cost",[853,917,918],{},"Hardware + ongoing maintenance",[853,920,921],{},"Lower lifecycle cost in retrofit",[56,923,924,925,928],{},"In practice, modern ESPs increasingly use ",[60,926,927],{},"both",": rappers handle the heavy bottom of the plate, sonic horns handle the upper plate area, the discharge electrodes and the hopper. The combination outperforms either alone.",[75,930,180],{"id":179},[144,932,933,937,942,947,951,955],{},[147,934,935],{},[65,936,244],{"href":221},[147,938,939],{},[65,940,941],{"href":136},"Tumbling-hammer rapper",[147,943,944],{},[65,945,946],{"href":803},"Magnetic-impulse-gravity rapper",[147,948,949],{},[65,950,187],{"href":84},[147,952,953],{},[65,954,163],{"href":390},[147,956,957],{},[65,958,207],{"href":111},{"title":209,"searchDepth":210,"depth":210,"links":960},[961,962,963],{"id":808,"depth":210,"text":809},{"id":826,"depth":210,"text":827},{"id":179,"depth":210,"text":180},"An ESP rapper is a mechanical device used to dislodge accumulated dust from the collecting and discharge electrodes of an electrostatic precipitator. Two principal designs dominate: tumbling-hammer rappers, favoured in European-style ESPs, and magnetic-impulse-gravity (MIGI) rappers, favoured in American-style ESPs.",{},[326,967,968,224,391,229],"tumbling-hammer-rapper","magnetic-impulse-gravity-rapper",{"title":970,"description":971},"ESP rapper — mechanical cleaning of collecting plates and discharge electrodes","An ESP rapper is the mechanical hammer or magnetic impulse device used to dislodge accumulated dust from ESP plates and discharge electrodes. Sonic horns complement and partly replace this duty.",[973,974],{"title":238,"url":239},{"title":975,"url":976},"Neundorfer — Sonic Horns to Enhance RA & Shaker Cleaning","https:\u002F\u002Fwww.neundorfer.com\u002Fknowledge-base\u002Fsonic-horns-to-enhance-ra-shaker-cleaning\u002F","glossary\u002Fesp-rapper","QhQ46PxPUjS4GrAWsOxuHzUNaT9DIyjEK5DT4bGc6os",{"id":980,"title":157,"aliases":981,"body":985,"category":216,"description":1091,"extension":218,"meta":1092,"navigation":220,"path":126,"relatedTerms":1093,"seo":1094,"sources":1097,"stem":1100,"term":157,"__hash__":1101},"glossary\u002Fglossary\u002Fback-corona.md",[982,983,984],"reverse ionisation","back ionisation","back corona",{"type":53,"value":986,"toc":1085},[987,1001,1005,1011,1031,1035,1051,1055,1061,1063],[56,988,989,991,992,994,995,997,998,1000],{},[60,990,157],{}," (also ",[896,993,982],{},") is a destructive failure mode in an ",[65,996,353],{"href":221}," in which the dust layer on the ",[65,999,85],{"href":84}," 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.",[75,1002,1004],{"id":1003},"when-back-corona-occurs","When back-corona occurs",[56,1006,1007,1008,1010],{},"Back-corona is triggered by high-",[65,1009,587],{"href":586}," ash — typically above ~10¹¹ Ω·cm — combined with a thick, undisturbed dust layer. The conditions are common on:",[144,1012,1013,1016,1025,1028],{},[147,1014,1015],{},"Low-sulphur Western US coals and sub-bituminous lignite",[147,1017,1018,1019,791,1021,1024],{},"Some ",[65,1020,72],{"href":67},[65,1022,1023],{"href":67},"WtE"," ashes",[147,1026,1027],{},"ESPs that have slipped behind on rapper maintenance",[147,1029,1030],{},"Cement-kiln ESPs after fuel switches or raw-mill stoppages",[75,1032,1034],{"id":1033},"symptoms","Symptoms",[144,1036,1037,1042,1045,1048],{},[147,1038,1039,1040],{},"Falling secondary voltage at the ",[65,1041,364],{"href":89},[147,1043,1044],{},"Rising secondary current with falling efficiency (the classic back-corona signature)",[147,1046,1047],{},"Persistent stack opacity rise that does not respond to rapper intensification",[147,1049,1050],{},"Sparking and arcing in the ESP power supply",[75,1052,1054],{"id":1053},"sonic-horns-and-back-corona","Sonic horns and back-corona",[56,1056,1057,1058,1060],{},"Because back-corona is fundamentally a dust-thickness problem, the strongest mitigation is to keep the plates thinner — continuously, not in periodic bursts. ",[65,1059,112],{"href":111}," 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.",[75,1062,180],{"id":179},[144,1064,1065,1069,1073,1077,1081],{},[147,1066,1067],{},[65,1068,244],{"href":221},[147,1070,1071],{},[65,1072,626],{"href":586},[147,1074,1075],{},[65,1076,312],{"href":94},[147,1078,1079],{},[65,1080,187],{"href":84},[147,1082,1083],{},[65,1084,207],{"href":111},{"title":209,"searchDepth":210,"depth":210,"links":1086},[1087,1088,1089,1090],{"id":1003,"depth":210,"text":1004},{"id":1033,"depth":210,"text":1034},{"id":1053,"depth":210,"text":1054},{"id":179,"depth":210,"text":180},"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.",{},[326,587,226,224,229],{"title":1095,"description":1096},"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.",[1098,1099],{"title":771,"url":772},{"title":238,"url":239},"glossary\u002Fback-corona","G6FyEgaY8SP8-TTBfd1_Oq0GIZQSeNR8jVcFF2LPxto",{"id":1103,"title":207,"aliases":1104,"body":1107,"category":1308,"description":1309,"extension":218,"meta":1310,"navigation":220,"path":111,"relatedTerms":1311,"seo":1318,"sources":1321,"stem":1329,"term":207,"__hash__":1330},"glossary\u002Fglossary\u002Fsonic-horn.md",[375,1105,1106],"sonic cleaning horn","industrial sonic horn",{"type":53,"value":1108,"toc":1301},[1109,1138,1142,1150,1154,1216,1220,1257,1261,1269,1271],[56,1110,258,1111,1113,1114,1118,1119,1122,1123,1122,1127,1122,1131,791,1135,138],{},[60,1112,717],{}," is a pneumatically-driven sound emitter that produces high-intensity, low-frequency sound waves — typically between 60 and 400 Hz at sound pressure levels of 140 to 180 dB — used to dislodge particulate fouling from inside industrial process equipment. Sonic horns are the most common form of ",[65,1115,1117],{"href":1116},"\u002Fglossary\u002Facoustic-cleaner","acoustic cleaner"," and the default specification for cleaning ",[65,1120,1121],{"href":221},"ESPs",", ",[65,1124,1126],{"href":1125},"\u002Fglossary\u002Ffabric-filter","baghouses",[65,1128,1130],{"href":1129},"\u002Fglossary\u002Fselective-catalytic-reduction","SCR catalysts",[65,1132,1134],{"href":1133},"\u002Fglossary\u002Fsuperheater","boiler heat-transfer surfaces",[65,1136,1137],{"href":736},"hoppers and silos",[75,1139,1141],{"id":1140},"how-a-sonic-horn-works","How a sonic horn works",[56,1143,1144,1145,1149],{},"Compressed plant air admitted through a ",[65,1146,1148],{"href":1147},"\u002Fglossary\u002Fsolenoid-valve","solenoid valve"," drives a metal diaphragm — typically titanium or 316 stainless — into resonant oscillation at the horn's fundamental frequency. The oscillating pressure field is amplified by an exponential bell horn and projected into the vessel as a near-spherical sound wave. Particulate already deposited on internal surfaces receives an oscillating acceleration that overcomes adhesion; loosened material is then carried out with the gas flow before it can sinter, bridge or bond. Because the cleaning is acoustic and non-contact, the horn can fire while the plant is online without tube erosion, refractory damage or thermal shock.",[75,1151,1153],{"id":1152},"key-parameters","Key parameters",[829,1155,1156,1166],{},[832,1157,1158],{},[835,1159,1160,1163],{},[838,1161,1162],{},"Parameter",[838,1164,1165],{},"Typical range",[848,1167,1168,1176,1184,1192,1200,1208],{},[835,1169,1170,1173],{},[853,1171,1172],{},"Fundamental frequency",[853,1174,1175],{},"60–400 Hz",[835,1177,1178,1181],{},[853,1179,1180],{},"Sound pressure level",[853,1182,1183],{},"140–180 dB",[835,1185,1186,1189],{},[853,1187,1188],{},"Compressed-air consumption",[853,1190,1191],{},"8–14 Nm³\u002Fmin at 4–7 bar",[835,1193,1194,1197],{},[853,1195,1196],{},"Operating temperature (with appropriate materials)",[853,1198,1199],{},"−40 °C to +500 °C",[835,1201,1202,1205],{},[853,1203,1204],{},"Firing cycle",[853,1206,1207],{},"5–15 s burst, repeated every 3–15 minutes",[835,1209,1210,1213],{},[853,1211,1212],{},"Mass",[853,1214,1215],{},"15–60 kg depending on horn size",[75,1217,1219],{"id":1218},"frequency-selection","Frequency selection",[56,1221,1222,1223,1122,1227,1231,1232,1122,1236,1240,1241,1122,1244,1248,1249,791,1253,138],{},"Lower frequencies (60–125 Hz) project longer wavelengths and penetrate further into large open vessels — ",[65,1224,1226],{"href":1225},"\u002Fglossary\u002Fpreheater-cyclone","preheater cyclones",[65,1228,1230],{"href":1229},"\u002Fglossary\u002Frecovery-boiler","recovery-boiler superheaters",", large ",[65,1233,1235],{"href":1234},"\u002Fglossary\u002Fesp-field-bus-section","ESP fields",[65,1237,1239],{"href":1238},"\u002Fglossary\u002Fsilo","silos",". Higher frequencies (230–400 Hz) carry more energy per unit volume and suit finer dust loads in ",[65,1242,1243],{"href":1125},"fabric-filter compartments",[65,1245,1247],{"href":1246},"\u002Fglossary\u002Fhoneycomb-catalyst","catalyst layers"," and smaller hopper geometries. See ",[65,1250,1252],{"href":1251},"\u002Fglossary\u002Flow-frequency-acoustic-cleaner","low-frequency acoustic cleaner",[65,1254,1256],{"href":1255},"\u002Fglossary\u002Fhigh-frequency-acoustic-cleaner","high-frequency acoustic cleaner",[75,1258,1260],{"id":1259},"sonic-horn-vs-steam-sootblower","Sonic horn vs steam sootblower",[56,1262,1263,1264,1268],{},"Sonic horns are increasingly specified alongside or in place of ",[65,1265,1267],{"href":1266},"\u002Fglossary\u002Fsteam-sootblower","steam sootblowers"," because they consume no boiler-grade steam, cause no tube erosion, require almost no moving parts and can fire every few minutes without operator intervention. They are less effective on hard, fused slag than retractable steam lances, so on furnace waterwalls and high-temperature superheaters they typically complement rather than replace mechanical cleaning.",[75,1270,180],{"id":179},[144,1272,1273,1278,1284,1290,1296],{},[147,1274,1275],{},[65,1276,1277],{"href":1116},"Acoustic cleaner",[147,1279,1280],{},[65,1281,1283],{"href":1282},"\u002Fglossary\u002Fsonic-sootblower","Sonic sootblower",[147,1285,1286],{},[65,1287,1289],{"href":1288},"\u002Fglossary\u002Fbell-horn","Bell horn",[147,1291,1292],{},[65,1293,1295],{"href":1294},"\u002Fglossary\u002Fdiaphragm-horn","Diaphragm horn",[147,1297,1298],{},[65,1299,1300],{"href":1251},"Low-frequency acoustic cleaner",{"title":209,"searchDepth":210,"depth":210,"links":1302},[1303,1304,1305,1306,1307],{"id":1140,"depth":210,"text":1141},{"id":1152,"depth":210,"text":1153},{"id":1218,"depth":210,"text":1219},{"id":1259,"depth":210,"text":1260},{"id":179,"depth":210,"text":180},"core-technology","A sonic horn is a pneumatically-driven sound emitter that produces high-intensity, low-frequency sound waves — typically between 60 and 400 Hz at sound pressure levels of 140 to 180 dB — used to dislodge particulate fouling from inside industrial process equipment. Sonic horns are the most common form of acoustic cleaner and the default specification for cleaning ESPs, baghouses, SCR catalysts, boiler heat-transfer surfaces and hoppers and silos.",{},[1312,1313,1314,1315,1316,1317],"acoustic-cleaner","acoustic-cleaning-system","sonic-sootblower","bell-horn","diaphragm-horn","low-frequency-acoustic-cleaner",{"title":1319,"description":1320},"Sonic horn — definition, frequency, SPL and industrial applications","A sonic horn is a pneumatically-driven low-frequency sound emitter (typically 60–400 Hz at 140–180 dB SPL) used to dislodge particulate fouling from boilers, ESPs, baghouses and process vessels.",[1322,1325,1326],{"title":1323,"url":1324},"Power Engineering — Sonic Horns: A User's Introduction","https:\u002F\u002Fwww.power-eng.com\u002Fcoal\u002Fsonic-horns-a-userrsquos-introduction\u002F",{"title":771,"url":772},{"title":1327,"url":1328},"Wikipedia — Sonic soot blowers","https:\u002F\u002Fen.wikipedia.org\u002Fwiki\u002FSonic_soot_blowers","glossary\u002Fsonic-horn","YzrhN0kKzqSaQo0wfn0rueNZ-V43mcg5zahqeWi3lnU",1782613735403]