’WPCs{ ÕhB‰=¼ Žšµ{®%fĪxFÜ#T+ū¹ļꕜŠ~‹Ž³ŽY€­åöUFąy½×ø©ŁĄ¶\_ˆ=%€z[cX„-Ė.‹šĶ(!¶øķ‰’ƒbdZÜ|]D?&+ i ‚ż¦™ŖĶ曄8ŗ—Q•Iļ+±žŽtD&żé’1$CšČ{/Ż€|sč:Ž'Oßd'\ uÆŗžļ²Ģ‚V÷xõįåĻ°ög:””/Ō’§õŁ ł s¾‡s•ŸˆŹOF“Xģ>…Ų ;QĶŅ5±UŻ{vp@…N—B½ōÆUµĪA•" ŅŌM”² ¶,MPÕ£xėDČ6źjØƏ‹»b€Ę3ēIĆSµlÉßļŸ˜NĶ°mĘ3ņśč—jķ`u {ŹTæĪ°2§čĆ_A’č`B“ĮżåiĢ@0cäõ(ćém'Ŗ|ų€“Cż›9 Ēŗž f“ @S5Ż13 o3U:7U*I7@ s7oū}7 0nxVU:ęVE WU>"WU:`WU*šWMÄWU,ČWMōWōWōWMųW 0nüWU>jXU*ØXØX@ ŅXoūÜXÜXÜXÜXÜXÜX B-×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w×w Ax 0n”x D3y BBy 0n_y 0KĶy AQzĘiz 0D/{˜0 ŠŻ ƒ3­'ŻÓ  ÓÓ °š…°œXÓŻ  ŻŌ_Ōßp€V<,(`~0©č!! `ĄœœE°X!!!!eX··pßā  (# (#°(#°(#āą € ąą  ąŌ‡ņ—įņņ ņŌŃ @ ŃŌ‡ō—įņņ,ņ—įŌą Š ąą  ąą ” ąą  ąą ž ąą # ąą Ø ąą - ąą ² ą€€Ō#†ōūlņņ,ō—įų#ŌŌ‡ōūlņņ ōūlŌEPA„452/F„03„030Ō#†ōūlņņ-ōūlŅ#ŌŌ‡ō—įņņ ōūlŌŠ X ŠÓ  ÓÓ?+Ü Ü4Œ ä <”ģDœōL¤ü!°š…?ÓŌ#†ōūlņņ,ō—į$#ŌĢĢą t ąŌ#†ņūlņņ ōūl"#Ōņ ņŌ‡ 7!ņ ņūlŌAir€Pollution€Technology€Fact€Sheetó óŌ#†ņūlņ! 7ś#ŌŠ ³[ ŠĢņ ņÓ  Óó ó ņ(*ŪL$””Ó  ÓÓ °š…°œXÓ QŻ ƒ3­)ŻÓ  ÓÓ °š…°œXÓŻ  ŻŌ_ŌßA€Y!) °°xd’’E°WxAߊ X ŠņņEPA„Ō_ŌCICAŌ_Ō€Fact€Sheetą€ÜÜ'(#ąWet€Electrostatic€Precipitator€(ESP)ˆŠ g Šą€™™<(#ąWire„Plate€TypeóóCģ.Ę FGHIJK€LMNO2};.8Ü 3|xO’U‹’ĄĄĄ Level 1Level 2Level 3Level 4Level 5ˆĒTABLE A Ń°Xј®TABLE B SŻ ƒ3­'ŻÓ  ÓÓ °š…°œXÓŻ  ŻŌ_ŌÓ  Óßp€V/<,(`~0©č!! `ĄœœE°X!!!!eX··pßā  (# (#°(#°(#āą @€ ąą @ ąŌ‡,ņ…ņņ ņŌŃ @ ŃŌ‡,ō…ņņ,ņ…Ōą @Š ąą @ ąą @” ąą @ ąą @ž ąą @# ąą @Ø ąą @- ąą @² ą€€Ō_ŌŌ#† ōė-ņņ,ō…#ŌŌ‡-ōė-ņņ ōė-ŌEPA„Ō_Ō452/F„03„030Ō#† ōė-ņņ-ōė-ī#ŌŌ‡,ō…ņņ ōė-ŌŠ X ŠÓ  ÓÓ?+Ü Ü4Œ ä <”ģDœōL¤ü!°š…?ÓŌ#† ōė-ņņ,ō…P#ŌĢĢÓ  Óą @t ąŌ_ŌŌ#† ņė-ņņ ōė-.#Ōņ ņŌ‡  „ !ņ ņė-ŌAirŌ_Ō€Pollution€Ō_ŌControl€TechnologyŌ_Ō€Ō_ŌŠ ³[ ŠFactŌ_Ō€Sheetó óŌ#† ņė-ņ! „ B#ŌŠ ģ” ŠĢŌ_Ōņ ņó óŌ_Ō(F33­$§§Ż ƒŪL!ŻÓ  ÓÓ °š…°œXÓŻ  Ż'ČČČČdxd ’WPC__††††††__ ’ĄoŠ™œ’’’0T#4\;c-C~%L„0R,S-]–:^—;ižHjžIt„Vu¦W€­d­eŒ“rŒµs—¼˜¼£Ć£Ä®ĖÆĖŗŅ«ŗӬʌŗŃįĒŅāČÜéÕŻéÖčšćéńäóųńōųņ-Q.T0V2[4_6f8i:m@zDF„Gˆ-O%,M)0P.5^:6g0BdDTxQrŽtv•w…ŸŠ9XF>\KC_Q±¢¤ø±ŗĒæŚįÜZqlŖ®²½Į->š.?š1A›¬/ž]jlfƒD‚jJD‚jJiYND…jg˜«/ ]jlfi`VgNƒjƒjVR‚jlJTYdš-Ŗ/œ`jjGG‚jVVƒjgdƒj]RjjTiž)©/.5œlƒjGT`dƒjd]ƒjdiVljlViœ-ˆ/.ˆ/.ˆ/.Š/(6œYJVd‚]VgƒjVVƒji‚gRjjlV›6'.†/+ˆ/)ˆ/'+ˆ/)$=› fDd]NJjƒjVTƒj…dJjjDg™=$'-„/,%%,…/.)$+…/.)$$)-„/'$%Œ" djVTjNjD‚jJJ‚jG‡`Djf‹ "ˆ&$%)++*'ƒ$'*‚+(%‚$%(‚+)%„$(‚+'‚$ˆ / djVVjgVjdJ‚jJJ‚jJdl‚jƒJTŒ„/  …6Ø$=…  „/Ž jTVjdVjdJ‚jGJ‚jJfl‡jg‹ ‡/ ƒ@%¦$„ ‡/Ž jJiVjVVJjdTƒjƒjRƒfƒdV`‰/ ‚5¦$9‚ ‰/Žl‡j`VƒjƒjVi]„VTN` Š/ @&¤$ Š/N‚jJJNVYiVƒjƒjVY‡jDŒ/ 7£$%? …/‚/‘fddf‚Vƒjƒj VfRJTJjVVDj ƒ/„/5¢$6…/ #‚/iJjV`‚jJVƒjƒjV„TjJjŽ ‚/ƒ „/  $5 „/ „‚/  Tjl`VjGDjgVƒjƒjVƒdljdJjŽ‚/…ƒ/1ž$:ƒ/…#‚/  DlfVji]jYVƒjƒjTiV‚jRdljŽ"// †#ƒ/1œ$:„/#†‚/ jJYldjVVƒjJ‚jJiGjjTJ‚jJ‚/‡‚/2š$Aƒ/ˆ‚/ jG„VjYVƒjJ‚j Jdjl]fNjJf ‚/ˆ#ƒ/30–$09ƒ/ ˆ#‚/ ‘Gj]‚iljdJ‚jGJ‚j JdigYVV`‘‚/‰ƒ/;“$0Aƒ/ #‰‚/‘ `jjGTTDjGJ‚jJTƒj‚iR„jGi"//#‰‚/C<0Ž$0Ah‚/ #‰#//“Y„jGgD‚jJVƒj‚NjjGVTDjR‚/Š! ‚/ <0ˆ$2\KC_Q±¢¤ø±ŗĒæŚįÜZqlŖ®²½Į->š.?š1A›¬/ž]jlfƒD‚jJD‚jJiYND…jg˜«/ ]jlfi`VgNƒjƒjVR‚jlJTYdš-Ŗ/œ`jjGG‚jVVƒjgdƒj]RjjTiž)©/.5œlƒjGT`dƒjd]ƒjdiVljlViœ-ˆ/.ˆ/.ˆ/.Š/(6œYJVd‚]VgƒjVVƒji‚gRjjlV›6'.†/+ˆ/)ˆ/'+ˆ/)$=› fDd]NJjƒjVTƒj…dJjjDg™=$'-„/,%%,…/.)$+…/.)$$)-„/'$%Œ" djVTjNjD‚jJJ‚jG‡`Djf‹ "ˆ&$%)++*'ƒ$'*‚+(%‚$%(‚+)%„$(‚+'‚$ˆ / djVVjgVjdJ‚jJJ‚jJdl‚jƒJTŒ„/  …6Ø$=…  „/Ž jTVjdVjdJ‚jGJ‚jJfl‡jg‹ ‡/ ƒ@%¦$„ ‡/Ž jJiVjVVJjdTƒjƒjRƒfƒdV`‰/ ‚5¦$9‚ ‰/Žl‡j`VƒjƒjVi]„VTN` Š/ @&¤$ Š/N‚jJJNVYiVƒjƒjVY‡jDŒ/ 7£$%? …/‚/‘fddf‚Vƒjƒj VfRJTJjVVDj ƒ/„/5¢$6…/ #‚/iJjV`‚jJVƒjƒjV„TjJjŽ ‚/ƒ „/  $5 „/ „‚/  Tjl`VjGDjgVƒjƒjVƒdljdJjŽ‚/…ƒ/1ž$:ƒ/…#‚/  DlfVji]jYVƒjƒjTiV‚jRdljŽ"// †#ƒ/1œ$:„/#†‚/ jJYldjVVƒjJ‚jJiGjjTJ‚jJ‚/‡‚/2š$Aƒ/ˆ‚/ jG„VjYVƒjJ‚j Jdjl]fNjJf ‚/ˆ#ƒ/30–$09ƒ/ ˆ#‚/ ‘Gj]‚iljdJ‚jGJ‚j JdigYVV`‘‚/‰ƒ/;“$0Aƒ/ #‰‚/‘ `jjGTTDjGJ‚jJTƒj‚iR„jGi"//#‰‚/C<0Ž$0Ah‚/ #‰#//“Y„jGgD‚jJVƒj‚NjjGVTDjR‚/Š! ‚/ <0ˆ$2\KC_Q±¢¤ø±ŗĒæŚįÜZqlŖ®²½Į->š.?š1A›¬/ž]jlfƒD‚jJD‚jJiYND…jg˜«/ ]jlfi`VgNƒjƒjVR‚jlJTYdš-Ŗ/œ`jjGG‚jVVƒjgdƒj]RjjTiž)©/.5œlƒjGT`dƒjd]ƒjdiVljlViœ-ˆ/.ˆ/.ˆ/.Š/(6œYJVd‚]VgƒjVVƒji‚gRjjlV›6'.†/+ˆ/)ˆ/'+ˆ/)$=› fDd]NJjƒjVTƒj…dJjjDg™=$'-„/,%%,…/.)$+…/.)$$)-„/'$%Œ" djVTjNjD‚jJJ‚jG‡`Djf‹ "ˆ&$%)++*'ƒ$'*‚+(%‚$%(‚+)%„$(‚+'‚$ˆ / djVVjgVjdJ‚jJJ‚jJdl‚jƒJTŒ„/  …6Ø$=…  „/Ž jTVjdVjdJ‚jGJ‚jJfl‡jg‹ ‡/ ƒ@%¦$„ ‡/Ž jJiVjVVJjdTƒjƒjRƒfƒdV`‰/ ‚5¦$9‚ ‰/Žl‡j`VƒjƒjVi]„VTN` Š/ @&¤$ Š/N‚jJJNVYiVƒjƒjVY‡jDŒ/ 7£$%? …/‚/‘fddf‚Vƒjƒj VfRJTJjVVDj ƒ/„/5¢$6…/ #‚/iJjV`‚jJVƒjƒjV„TjJjŽ ‚/ƒ „/  $5 „/ „‚/  Tjl`VjGDjgVƒjƒjVƒdljdJjŽ‚/…ƒ/1ž$:ƒ/…#‚/  DlfVji]jYVƒjƒjTiV‚jRdljŽ"// †#ƒ/1œ$:„/#†‚/ jJYldjVVƒjJ‚jJiGjjTJ‚jJ‚/‡‚/2š$Aƒ/ˆ‚/ jG„VjYVƒjJ‚j Jdjl]fNjJf ‚/ˆ#ƒ/30–$09ƒ/ ˆ#‚/ ‘Gj]‚iljdJ‚jGJ‚j JdigYVV`‘‚/‰ƒ/;“$0Aƒ/ #‰‚/‘ `jjGTTDjGJ‚jJTƒj‚iR„jGi"//#‰‚/C<0Ž$0Ah‚/ #‰#//“Y„jGgD‚jJVƒj‚NjjGVTDjR‚/Š! ‚/ <0ˆ$2" €W@94.0 €W@Y €V@90.0„„‰€V@‰Š90.0ŠYOM^*P ?" €V@90.0 $  €V@Y YŠÖ€¶Öņ ņĢĢApplicable€Source€Type:€€ó óPointŠ ł,ė"A ŠŠ Ö-Č#B ŠŃgŠŃā āŃ°XŃā āŃ  ŃŌ_ŌŌ_Ōņ ņŌ& Q ŌTypical€Industrial€Applications:ó óŠ ° ŠĢÓ  ÓWet€ESPs€are€used€in€situations€for€which€dry€are€not€suited,€such€as€when€the€material€to€be€collected€is€wet,Ļsticky,€flammable,€explosive,€or€has€a€high€resistivity.€€Also,€as€higher€collection€efficiencies€have€become€moreĻdesirable,€wet€ESP€applications€have€been€increasing€(EPA,€1998).€€Ō'Q°qŌWet€ESPs€are€commonly€used€by€theĻwood€products,€metalurgical,€and€sulfuric€acid€manufacturing€industries,€though€other€ESP€types€are€alsoĻemployed.€€Common€applications€of€wet€wire„plate€ESPs€are€presented€in€Table€2.ĢÓ¶ÓĢÓ  Óņ ņą @ ąTable€2.€€Typical€Industrial€Applications€of€Wet€Wire„Plate€ESPs€(EPA,€1998)ó óŠ ˜ č ŠÓēÓĢŌ*žƒd ŹdN Kd N Kd ĻKd ĻĻKd Ļ°(#°(#žŌŌ,<dd ŌŌ,ždd ŌŌ+  ŌŠ %€YY R ¢  ‚$‚ƒƒ%ŠApplicationŠ +€YYv Ę YY +ŠSource€Category€CodeĻ(SCC)Š 2(S£  $ YY ‚$‚ƒƒ2ŠChemical€ManufactureŠ  XØ  Š3„01„001...999Š #XØ  $ ‚$‚ƒƒ#ŠNon„Ferrous€Metals€Processing€(Primary€andĻSecondary):Š  :Š  ŠŠ #]­  $ ‚$‚ƒƒ#ŠÓ  ÓCopperŠ ? 0 Š3„03„005Ģ3„04„002Š #l $ ‚$‚ƒƒ#ŠÓ  ÓLeadŠ !q0 Š3„03„010Ģ3„04„004Š #žN $ ‚$‚ƒƒ#ŠÓ  ÓZincŠ S0 Š3„03„030Ģ3„04„008Š #ą0 $ ‚$‚ƒƒ#ŠÓ  ÓAluminumŠ å50 Š3„03„000...002Ģ3„04„001Š #Ā $ ‚$‚ƒƒ#ŠÓ  ÓOther€metals€productionŠ Ē0 Š3„03„011...014Ģ3„04„005...006Ģ3„04„010...022Š ,"Ń" $ ‚$‚ƒƒ„„,ŠÓ  ÓFerrous€Metals€Processing:Š †Ö# ŠŠ ,"†Ö$ $ ‚$‚ƒƒ„„,ŠIron€and€Steel€ProductionŠ ‹Ū%3 Š3„03„008...009Š ,"‹Ū& $ ‚$‚ƒƒ„„,ŠSteel€FoundriesŠ ą'3 Š3„04„007,„009Š #ą( $ ‚$‚ƒƒ#ŠMineral€Products:Š  •å) ŠŠ ,"•å* $ ‚$‚ƒƒ„„,ŠStone€Quarrying€and€ProcessingŠ @6š ź+3 L“@1235‰L“@‰@Š3„05„020Š ND1š ź, L“@1235 $ L“@ ‚$‚ƒƒ„„NŠOtherŠ Ÿ!ļ-3 Š3„05„003...999Š *€YŸ!ļ. $ ‚$‚ƒƒ*ŠWood,€Pulp,€and€PaperŠ M€Y<¤"ō/Y ō“@1277‰ō“@‰MŠ3„07„001ŠPFD¤"ō0 ō“@1277 $  ō“@Y PŠĢņ ņŌ& — ŌEmission€Stream€Characteristics:ó óŠ b$²1 ŠĢÓ  Óą  ąņ ņa.ą0 ™ ąAir€Flow:ó 󀀀Typical€gasŌ'—b$N!Ō€flow€rates€for€wet€wire„plate€ESPs€are€50€to€250€standard€cubic€meters€perŠ &l!3 Šsecond€(smņņ3óó/sec)€(100,000€to€500,000€standard€cubic€feet€per€minute€(scfm)).€€Most€smaller€plate„Š ł&I"4 Štype€ESPs€(50€smņņ3óó/sec€to€100€smņņ3óó/sec,€or€100,000€to€200,000€scfm)€use€flat€plates€instead€of€wiresŠ Ö' Šfor€the€high„voltage€electrodes€(AWMA,€1992).Š ™(#™(# ŠĢą  ąņ ņb.ą0 ™ ąTemperature:ó 󀀀Wet€wire„plate€ESPs€are€limited€to€operating€at€temperatures€lower€thanŠ m*½%8 Šapproximately€80€to€90ššC€(170€to€190ššF)€(EPA,€1998;€Flynn,€1999).€Š ™(#™(# ŠĢą  ąņ ņc.ą0 ™ ąPollutant€Loading:ó 󀀀Typical€inlet€concentrations€to€a€wire„plate€ESP€are€2€to€110€g/mņņ3óó€(1€to€50Š -T(; Šgr/scf).€€It€is€common€to€pretreat€a€waste€stream,€usually€with€a€water€spray€or€scrubber,€to€bring€theŠ į-1)< Štemperature€and€pollutant€concentration€into€a€manageable€range.€€Highly€toxic€flows€withĻconcentrations€below€1€g/mņņ3óó€(0.5€gr/scf)€are€also€sometimes€controlled€with€ESPs€(Bradburn,€1999;Š Ż ŠBoyer,€1999;€Brown,€1999).Š ™(#™(# ŠÓJ!ÓĢÓ  Óą  ąņ ņd.ą0 ™ ąOther€Considerations:ó 󀀀Dust€resistivity€is€not€a€factor€for€wet€ESPs,€because€of€the€high€humidityŠ $t Šatmosphere€which€lowers€the€resistivity€of€most€materials.€€Particle€size€is€much€less€of€a€factor€forĻwet€ESPs,€compared€to€dry€ESPs.€€Much€smaller€particles€can€be€efficiently€collected€by€wet€ESPsĻdue€to€the€lack€of€resistivity€concerns€and€the€reduced€reentrainment€(Flynn,€1999).Š ™(#™(# ŠÓ^&ÓĢņ ņEmission€Stream€Pretreatment€Requirements:ó óŠ u Å  ŠĢÓ  ÓWhen€the€pollutant€loading€is€exceptionally€high€or€consists€of€relatively€large€(>€2€ššm)€particles,€venturiĻscrubbers€or€spray€chambers€may€be€used€to€reduce€the€load€on€the€ESP.€Much€larger€particles€(>€10€ššm),Ļare€controlled€with€mechanical€collectors€such€as€cyclones.€€Gas€conditioning€equipment€to€reduce€both€inletĻconcentration€and€gas€temperature€is€occasionally€used€as€part€of€the€original€design€of€a€wet€ESP€(AWMA,Ļ1992;€Flynn,€1999).€ĢÓŒ(ÓĢņ ņCost€Information:ó óŠ ]­ ŠĢÓ  ÓThe€following€are€cost€ranges€(expressed€in€2002€dollars)€for€wire„plate€ESPs€of€conventional€design€underĻtypical€operating€conditions,€developed€using€EPA€cost„estimating€spreadsheets€for€dry€wire„plate€ESPs€withĻadjustments€made€to€reflect€wet€wire„plate€ESPs€(EPA,€1996).€€Costs€can€be€substantially€higher€than€in€theĻranges€shown€for€pollutants€which€require€an€unusually€high€level€of€control,€or€which€require€the€ESP€to€beĻconstructed€of€special€materials€such€as€titanium.€€Capital€and€operating€costs€are€generally€higher€due€toĻnoncorrosive€materials€requirements,€increased€water€usage,€and€treatment€and€disposal€of€wet€effluent.€€InĻmost€cases,€smaller€units€controlling€a€low€concentration€waste€stream€will€not€be€as€cost€effective€as€a€largeĻunit€cleaning€a€high€pollutant€load€flow€(EPA,€1998).Ģӝ*ÓĢą  ąņ ņa.ą0 ™ ąCapital€Cost:ó ó€€$ńCń42ńCńńCń65ńCń,000€to€$ńDń85ńDńńDń130ńDń,000€per€smņņ3óó/sec€($20€to€$40€per€scfm)ŠÜ,™(#™(# ŠĢą  ąņ ņb.ą0 ™ ąO€&€M€Cost:ó ó€€$1ńEń1ńEńńEń2ńEń,000€to€$ńFń85ńFńńFń95ńFń,000€per€smņņ3óó/sec€($5€to€$40€per€scfm),€annuallyŠ–ę™(#™(# ŠĢą  ąņ ņc.ą0 ™ ąAnnualized€Cost:ó ó€€$ńGń19ńGńńGń22ńGń,000€to€$1ńHń0ńHńńHń1ńHń0,000€per€smņņ3óó/sec€($9€to€$47€per€scfm),€annuallyŠP   ™(#™(# ŠĢą  ąņ ņd.ą0 ™ ąCost€Effectiveness:ó ó€€$ńIń53ńIńńIń60ńIń€to€$ńJń570ńJńńJń600ńJń€per€metric€ton€($48€to€$520€per€short€ton)Š "Z"™(#™(# ŠńKńą  ąą ™ ąą  ąą £ ąą ( ąą ­ ąą 2 ąą · ąńKńĢņ ņŌ& — ŌTheory€of€Operation:ó óŠ Ä#$ ŠĢÓ  ÓAn€ESP€is€a€particulate€control€deviceŌ'—Ä#?1Ō€that€uses€electrical€forces€to€move€particles€entrained€within€an€exhaustĻstream€onto€collector€plates.€€The€entrained€particles€are€given€an€electrical€charge€when€they€pass€throughĻa€corona,€a€region€where€gaseous€ions€flow.€€Electrodes€in€the€center€of€the€flow€lane€are€maintained€at€highĻvoltage€and€generate€the€electrical€field€that€forces€the€particles€to€the€collector€walls.€€In€wet€ESPs,€theĻcollectors€are€either€intermittently€or€continuously€washed€by€a€spray€of€liquid,€usually€water.€€The€collectionĻhoppers€used€by€dry€ESPs€are€replaced€with€a€drainage€system.€€The€wet€effluent€is€collected,€and€oftenĻtreated€on„site€(EPA,€1998).ĢĢIn€the€wire„plate€ESP,€the€exhaust€gas€flows€horizontally€and€parallel€to€vertical€plates€of€sheet€metal.€€PlateĻspacing€is€typically€between€19€to€38€cm€(9€to€18€inches€(in.))€(AWMA,€1992).€€The€high€voltage€electrodes€areĻlong€wires€that€are€weighted€and€hang€between€the€plates.€€Some€later€designs€use€rigid€electrodes€(hollowŠ  .p)0 Špipes€approximately€25€mm€to€40€mm€in€diameter)€in€place€of€wire€(Cooper€and€Alley,€1994).€€Within€each€flowĻpath,€gas€flow€must€pass€each€wire€in€sequence€as€it€flows€through€the€unit.€€The€flow€areas€between€the€platesĻare€called€ducts.€€Duct€heights€are€typically€6€to€14€meters€(m)€(20€to€45€feet)€(EPA,€1998).ĢĢThe€power€supplies€for€the€ESP€convert€the€industrial€AC€voltage€(220€to€480€volts)€to€pulsating€DC€voltage€inĻthe€range€of€20,000€to€100,000€volts€as€needed.€€The€voltage€applied€to€the€electrodes€causes€the€gas€betweenĻthe€electrodes€to€break€down€electrically,€an€action€known€as€a€š šcorona.šš€€The€electrodes€are€usually€given€aĻnegative€polarity€because€a€negative€corona€supports€a€higher€voltage€than€does€a€positive€corona€beforeĻsparking€occurs.€€€The€ions€generated€in€the€corona€follow€electric€field€lines€from€the€wires€to€the€collectingĻplates.€€Therefore,€each€wire€establishes€a€charging€zone€through€which€the€particles€must€pass.€€As€largerĻparticles€(>10€ššm€diameter)€absorb€many€times€more€ions€than€small€particles€(>1€ššm€diameter),€the€electricalĻforces€are€much€stronger€on€the€large€particles€(EPA,€1996).ĢĢDue€to€necessary€clearances€needed€for€nonelectrified€internal€components€at€the€top€of€the€ESP,€part€of€theĻgas€may€flow€around€the€charging€zones.€€This€is€called€š šsneakagešš€and€places€an€upper€limit€on€the€collectionĻefficiency.€€Anti„sneakage€baffles€are€placed€to€force€the€sneakage€flow€to€mix€with€the€main€gas€stream€forĻcollection€in€later€sections€(EPA,€1998).ĢĢWet€ESPs€require€a€source€of€wash€water€to€be€injected€or€sprayed€near€the€top€of€the€collector€plates€eitherĻcontinuously€or€at€timed€intervals.€€This€wash€system€replaces€the€rapping€mechanism€usually€used€by€dryĻESPs.€€The€water€flows€with€the€collected€particles€into€a€sump€from€which€the€fluid€is€pumped€or€drained.€€AĻportion€of€the€fluid€may€be€recycled€to€reduce€the€total€amount€of€water€required.€€The€remainder€is€pumped€intoĻa€settling€pond€or€passed€through€a€dewatering€stage,€with€subsequent€disposal€of€the€sludge€(AWMA,€1992).ĢĢUnlike€dry€ESPs,€resistivity€of€the€collected€material€is€generally€not€a€major€factor€in€performance.€€BecauseĻof€the€high€humidity€in€a€wet€ESP,€the€resistivity€of€particles€is€lowered,€eliminating€the€š šback€coronašš€condition.€ĻThe€frequent€washing€of€the€plates€also€limits€particle€buildup€on€the€collectors€(EPA,€1998).ĢĢņ ņAdvantages:ó óŠ Ü, ŠĢWet€wire„plate€ESPs€and€other€ESPs€in€general,€because€they€act€only€on€the€particulate€to€be€removed,€andĻonly€minimally€hinder€flue€gas€flow,€have€very€low€pressure€drops€(typically€less€than€13€mm€(0.5€in.)€waterĻcolumn).€€As€a€result,€energy€requirements€and€operating€costs€tend€to€be€low.€€They€are€capable€of€very€highĻefficiencies,€even€for€very€small€particles.€€Operating€costs€are€relatively€low.€€ESPs€are€capable€of€operatingĻunder€high€pressure€(to€1,030€kPa€(150€psi))€or€vacuum€conditions,€and€relatively€large€gas€flow€rates€can€beĻeffectively€handled€(AWMA,€1992).ĢĢWet€ESPs€can€collect€sticky€particles€and€mists,€as€well€as€highly€resistive€or€explosive€dusts.€€The€continuousĻor€intermittent€washing€with€a€liquid€eliminates€the€reentrainment€of€particles€due€to€rapping€which€dry€ESPsĻare€subject€to.€€The€humid€atmosphere€that€results€from€the€washing€in€a€wet€ESP€enables€them€to€collect€highĻresistivity€particles,€absorb€gases€or€cause€pollutants€to€condense,€and€cools€and€conditions€the€gas€stream.€ĻLiquid€particles€or€aerosols€present€in€the€gas€stream€are€collected€along€with€particles€and€provide€anotherĻmeans€of€rinsing€the€collection€electrodes€(EPA,€1998).ĢĢņ ņDisadvantages:ó óŠ ¬*ü%, ŠĢESPs€generally€have€high€capital€costs.€€The€wire€discharge€electrodes€(approximately€2.5€mm€(0.01€in.)€inĻdiameter)€are€high„maintenance€items.€€Corrosion€can€occur€near€the€top€of€the€wires€because€of€air€leakageĻand€acid€condensation.€€Also,€long€weighted€wires€tend€to€oscillate€„€the€middle€of€the€wire€can€approach€theŠ  .p)0 Šplate,€causing€increased€sparking€and€wear.€€Newer€ESP€designs€are€tending€toward€rigid€electrodes€(CooperĻand€Alley,€1994).ĢĢń5ńą  ąń5ńESPs€in€general€are€not€suited€for€use€in€processes€which€are€highly€variable€because€they€are€very€sensitiveĻto€fluctuations€in€gas€stream€conditions€(flow€rates,€temperatures,€particulate€and€gas€composition,€andĻparticulate€loadings).€ESPs€are€also€difficult€to€install€in€sites€which€have€limited€space€since€ESPs€must€beĻrelatively€large€to€obtain€the€low€gas€velocities€necessary€for€efficient€PM€collection€(Cooper€and€Alley,€1994).€ĻRelatively€sophisticated€maintenance€personnel€are€required,€as€well€as€special€precautions€to€safeguardĻpersonnel€from€the€high€voltage.€€Ozone€is€produced€by€the€negatively€charged€electrode€during€gas€ionizationĻ(AWMA,€1992).€€Wet€ESPs€add€the€complexity€of€a€wash€system,€and€the€fact€that€the€resulting€slurry€mustĻbe€handled€more€carefully€than€a€dry€product,€and€in€many€cases€requires€treatment,€especially€if€the€dust€canĻbe€sold€or€recycled.€€Wet€ESPs€are€limited€to€operating€at€stream€temperatures€under€approximately€80€to€90ššCĻ(170€to€190ššF),€and€generally€must€be€constructed€of€noncorrosive€materials€(EPA,€1998;€Flynn,€1999).€ĢĢņ ņŌ& — ŌOther€Considerations:ó óŠ Ę  ŠĢń6ńą  ąń6ńFor€wet€ESPsŌ'—ĘJKŌ,€consideration€must€be€given€to€handling€wastewaters.€€For€simple€systems€with€innocuousĻdusts,€water€with€particles€collected€by€the€ESP€may€be€discharged€from€the€ESP€system€to€a€solids„removingĻclarifier€(either€dedicated€to€the€ESP€or€part€of€the€plant€wastewater€treatment€system)€and€then€to€finalĻdisposal.€€More€complicated€systems€may€require€skimming€and€sludge€removal,€clarification€in€dedicatedĻequipment,€pH€adjustment,€and/or€treatment€to€remove€dissolved€solids.€€Spray€water€from€an€ESPĻpreconditioner€may€be€treated€separately€from€the€water€used€to€wash€the€ESP€collecting€plates€so€that€theĻcleaner€of€the€two€treated€water€streams€may€be€returned€to€the€ESP.€€Recirculation€of€treated€water€to€theĻESP€may€approach€100€percent€(AWMA,€1992).Ģń7ńÓł1Óń7ńĢņ ņReferences:ó óŠ E• ŠĢAWMA,€1992.€€Air€&€Waste€Management€Association,€€ņņAir€Pollution€Engineering€Manualóó,€Van€NostrandŠ ’O ŠReinhold,€New€York.€ĢĢBoyer,€1999.€€James€Boyer,€Beaumont€Environmental€Systems,€(724)€941„1743,€personal€communicationĻwith€Eric€Albright,€January€18,€1999.ĢĢBradburn,€1999.€€Keith€Bradburn,€ABB€Environmental€Systems,€(800)€346„8944,€personal€communicationĻwith€Eric€Albright,€January€18,€1999.ĢĢBrown,€1999.€€Bob€Brown,€Environmental€Elements€Corp.,€(410)€368„6894,€personal€communication€withĻEric€Albright,€January€18,€1999.ĢĢCooper€&€Alley,€1994.€€C.€D.€Cooper€and€F.€C.€Alley,€ņņAir€Pollution€Control:€A€Design€Approachóó,€SecondŠ [&«!' ŠEdition,€Waveland€Press,€Inc.€IL.ĢĢEPA,€1996.€€U.S.€EPA,€Office€of€Air€Quality€Planning€and€Standards,€š šOAQPS€Control€Cost€Manual,šš€FifthĻEdition,€EPA€453/B„96„001,€Research€Triangle€Park,€NC.€February.€ĢĢEPA,€1997.€€U.S.€EPA,€Office€of€Air€Quality€Planning€and€Standards,€š šCompilation€of€Air€Pollutant€EmissionĻFactors,€Volume€I,€Fifth€Edition,€Research€Triangle€Park,€NC.,€October.Ģā āŠ C-“(/ ŠEPA,€1998.€€U.S.€EPA,€Office€of€Air€Quality€Planning€and€Standards,€š šStationary€Source€ControlĻā āTechniques€Document€for€Fine€Particulate€Matter,šš€EPA„452/R„97„001,€Research€Triangle€Park,€NC.,ĻOctober.ĢĢFlynn,€1999.€€Brian€Flynn,€Beltran€Associates,€Inc.,€(718)€338„3311,€personal€communication€with€EricĻAlbright,€February€5,€1999.ĢĢICAC,€1999.€€Institute€of€Clean€Air€Companies€internet€web€page€www.icac.com,€Control€TechnologyĻInformation€„€Electrostatic€Precipitator,€page€last€updated€January€11,€1999.ĢSTAPPA/ALAPCO,€1996.€€State€and€Territorial€Air€Pollution€Program€Administrators€and€Association€ofĻLocal€Air€Pollution€Control€Officials,€š šControlling€Particulate€Matter€Under€the€Clean€Air€Act:€A€Menu€ofĻOptions,šš€July.€ĢĢĢ