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Developmentsin the control of fine particulateair emissions*
K.DARCOVICH,K.A.JONASSONandC.E.CAPES**Institutefor ChemicalProcessandEnvironmentalTechnology, NationalResearchCouncilof Canada,Ottawa,Ontario,KIAOR6CanadaReceived21October 1996;accepted26 November 1996
Abstract-Acomprehensivereviewof emergingtechnologiesandrecentdevelopmentsinair pollutioncontrolequipmentand processesspecificallyaddressing particulateremovalis providedhere.Emphasisis
placedonapproacheswithahighdegreeof noveltyand/or involvingnewmodificationstoconventionalsystems.Someemergingareas,suchaswasteincineration,have producednew particulatematter controlneedswhichwill bediscussed.Thesubjectandkey problemareasareintroduced,followed bya brief descriptionof thevarious particlecapturemechanismsandthe principaltechnologygroupswhichexploitthesemechanismstoachieve particlecapture.Moredetailsarethengivenfor specificinnovative projects,organized principally bytechnology,aswellas byindustrysector.Finally,alternativestoend-of-pipetreatmentstrategiesarediscussed.Anextensivelistof referencesisincluded,representativeof athoroughliteraturesurvey.
1.INTRODUCTIONIn the1970s,it becamewidelyrecognizedthatfine particlesfromindustrial pro-cessesandautomobileshadasignificantlymorenegativeenvironmentalimpactthantherelativelylarge particlesof windblowndustregulated bytheUSEnviromentalProtectionAgency(EPA)as 'totalsuspended particulatematter'(TSP).Intermsof air pollutioncontrol, particleswithaerodynamicdiameterslessthan10¡Lm,referredto asPM10,have beentargettedfor removal.StudiesinCanadaandtheUShavetypicallyidentifiedsourcessuchasfugitivedust,construction,agricultureandfuelcombustionasthemaincontributorstoPM10loadings.At presentintheUS,PM10is aguidelineusedfor air qualitystandards.Pressurehas been buildingtotightenthestandardtoPM2.5.With particlesinthisfiner sizefraction,impactsonhumanhealtharemore pronouncedduetoanincreasedrelativetoxicsconcentration,aswellasreadyrespirability.
*NRCC No.37624.**Towhomcorrespondenceshould beaddressed.
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Advancedfine particleremovaltechnologiesareconsideredto beendof pipesys-temscapableof treatingPM10(or evenPM2.5)materialto producegasstreamemis-sionsincompliancewithair qualitystandards,andwithsomemarginto beeffectiveunder
tighter anticipatedfuture
regulations.Emission
preventionstrategiesarealso
included.In1990theUSEPA produceda listof 189HazardousAir Pollutants(HAPs)under theCleanAir ActAmendments.ThisActidentifiesspecificchemicalelementsandcompoundsas harmfulto healthandenvironment,and placesrestrictionsonthe permissibleemissionslevels.Thecontrolof HAPsimpacts particulateremoval
practiceinthatsomeHAPsarereleasedin solidform(mostlymetals),or in thecaseof somevolatileorganiccompounds(VOCs),areadsorbedonto particulatesalso
presentintheemissionstream.Theremovalof particles(liquids,solidsor mixtures)fromagasstreamrequirestheir
depositionandattachmenttoa surface.Thesurfacemay becontinuous,suchasthewallandconeof acycloneor thecollection platesof anelectrostatic precipitator,or thesurfacemay bediscontinuoussuchasspraywater dropletsinascrubbingtower.Oncedepositedona surface,a meansmust be providedto removethecollected
particlescontinuouslyor atintervalswithoutappreciablereentrainmentintothegasstream.
Themagnitudeof theforcetomovea particletowardacollectingsurfaceisinflu-encedmarkedly bythesizeandshapeof the particle.Gravitysettlingwill beefficientonlyonlarge particles;40-50/-tmis thelower limitof effectiveness.Flowline
interceptionandinertialimpactionwill beeffectiveon particlesdownto2-3¡Lm.Diffusionaldepositionandthermal precipitation becomeincreasinglyefficientwithdecreasein particlesizeandarehighlyefficienton particlessmaller than0.2itm.Electrostaticforcesarethestrongestforcesthatcanactonfine particles(looselydefinedas particlessmaller than2-3um).
Controlequipmentfor particulatesfallintofivegeneralclasses,i.e.gravity/inertialsettlers;centrifugalseparators(cyclones);electrostatic precipitators;fabric, packed
bedor rigid barrier filters;andwetscrubbers.Suchequipmentmust bematchedtothe particlecharacteristicsaswellas variablessuchasflowrate,temperatureand
requiredremovalefficiency.It is wellrecognizedthatnouniversal particleremovalmethodexistswhichwillsatisfyall problemsandconditions.Thechoiceis often basedonacompromise betweentechnicalandeconomicfactors.
This presentreviewstemsfrom participationin a techno-economicassessmentof emergingair pollutioncontroltechnologies[1].Other overviewsof thefieldof fine
particleremovaltechnologyareavailableina number of monographshavingvarious perspectives[2-7].
Thisarticlefirst presentsa brief overviewof particleremovalmechanisms,thenasummaryof thegenerictechnologygroupsthathave beendevelopedtoexploitthese
mechanisms.The bulk of thereviewwillthenfocusonspecificnoveltechnologies, processesandfundamentalmechanismsthathave beenidentifiedfromanextensiveliteraturesurveyonthesubject.Theemphasiswill betohighlightinnovative pre-commercialsystemsaswellasrecentresearchfindingswith potentialapplicationtoadvancedfine particleremovaltechnologies.
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1. I.Particleremovalmechanisms
1.1.1.Sieving.Whena gasstreamcontaining particulatematter passesthrougha collectiondevice(typicallya screen)wherethegaps betweenthecollectorsaresmaller thanthe particledimension,thesolidis retainedonthe barrier.Generally,thismechanismis bestsuitedfor larger particlesandisnotcommonfor industrialgascleaning.
1.1.2.Gravitysettling.All particlesaresubjecttogravityandwillattaina terminalsettlingvelocityunder quiescentconditions.Brownianmotion,thermal,turbulentandconvectiveforcesmayactonverysmall particlesto stabilizetheir suspension
inair.Generally,however,a netdownwardmotionwillarisefor particleslarger than5ttm.Thecollector may befibrous,agranular bedor simplythefloor of asettlingchamber.Gravitysettlingis nota commonfine particulatematter removalmechanism.
1.1.3.Inertialimpaction.Larger particlesina gasstreamwill possessenoughmomentumtodeviatefromthefluidstreamlinesandcollidewithacollectingobstacleintheir path.These particlesareseparated byimpaction.Collectionefficiencyisenhanced bylarger particlediameter or conversely,a smaller collector dimension
thatwillenhancecontact.Certaintypesof fibrefilters, packed beds,spraysystems,impingingstreamcollectorsandcyclonesemploythisremovalmechanism.
1.1.4.Interception.A particle beingcarried byafluidmayexperienceagrazingcollisionwithacollector,whichis knownasinterception.Thismechanismdiffersfromimpactioninthesensethatthe particledoesnotactuallyneedtodepartfromthefluidstreamlinetocontactthecollector.Thenatureof thefluidflowislessimportantfor thismechanism.Interceptionandimpactionmayoperatesimultaneously,althoughthelatter becomesdominantat
higher gasvelocities.Internal
tortuosityina filter
mediumwillcausenumerousgasstreamdirectionchangesandwillincreasethe probabilitythatinterceptionor impactionwouldoccur.
Collectionefficiencygenerallyincreaseswithincreasing particletocollector sizeratio.Examplesincludethecollectionof particlesinfibrousor granular filter media.
1.1.5.Diffusion.Concentrationgradientsof particlesin agaseousmediumwillinducemigrationof particulatematter toregionsof lower localconcentration.Thegas phase particleconcentrationnexttocollector surfacesisnormallysmall,sothat
thereisusuallya diffusionalforceactingonthe particlestocausethemtoapproachthecollector.Smallgas phasevelocitiesand particlediametersenhancecollection bythismechanism.Alargecollector surfaceareaisnormallyrequiredfor separationsto beeffectedinthisway.Fibrousandgranular mediaandsmallliquiddropletscanremove particulatematter bythismechanism.
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1.1.6.Electrostatics.Inherently, particulatematter will possesssomedegreeof surfaceelectricalcharge.Variouswaysof conditioningthefeedstreamcanenhancethischarging.Anexternallyimposedelectricalfieldwillapplya forceonchargedmatter andwillsetit in motiontowardsa collector of
oppositeelectrical
charge.Electrostaticcollectionisimproved byincreasingthemagnitudeof theelectricalattraction,decreasing particlesizeanddecreasingtheflowrateof thegasstream.Electrostatic precipitatorsareatechnologyemployingthiscapturemechanism.The
performanceof other typesof collectorssuchasfabricfiltersandsomescrubbersisenhancedwithelectrostaticcharging.
1.1.7.Other mechanisms.Other phenomenaexistwhichcannot beusedaloneascapturemechanisms, butknowledgeof their effectsis constructiveindesigningadvancedfine
particleremoval
equipment.Particlessuspendedinagasareknowntodescendthermalgradients,havingatendencytomovetowardscoldsurfacesor awayfromhotsurfaces.Thisis knownasthermophoresis.Basically,a coldcollectionsystemwillenhance particleremovalfroma hotgasstream.Ina parallelfashion,anyspeciesof gasdiffusingwithina carrier streamwillinduce
a flux.For example, particleswouldgenerally becarriedtowarda surfacewherecondensationisoccurringandawayfroma surfacewhereevaporationisoccurring.
1.1.8.Generalremovalmechanismconsiderations.Whileallof theabove particle
removalmechanismscanactatthesametime,theyhavemoremarkedeffectsfor specific particlesizes.Figure1showsschematicallytheeffectof particlediameter ontheefficiencyof thevariouscapturemechanisms[8].It can beseenherethatif thecontributionsof thevariousmechanismsaresummed,thereexistsa particlediameter
Figure1.Relativeextentof particulateremovalmechanismsasafunctionof diameter.Adaptedfrom[8].
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for whichthe particulatematter removalis leastefficient.Ingeneral,allowingfor variationsinthematerialof whichthe particulatematter iscomposed,thediameter rangeof 0.2-2ttm presentsthemostdifficultyfor air pollutioncontrolequipment.
InFig.1,theremovalefficiencyonthey-axisisdefinedastheratioof the particulatematter concentrationinthegasstreamenteringasystemtothatleavingit.
1.1.9.Additionalconsiderations.Inadditiontothetechnologiessummarizedabove,therearea fewmoretechnicaloptionstoconsider for theremovalof airborne partic-ulatematter.Processcontrolequipmentcan beusedtooptimizethe performanceof almostalltypesof existingequipment.
Changescan bemadeto processeswhichgenerate particulateemissions.For exam- ple,cleaner burningfuelsor combustor temperaturecontrolscansignificantlyreduce
theamountof particulatematter createdandcarried byfluegases,therebymakingitsremovallessdifficult.Modellingof unit performancecanalso be beneficial.Anunderstandingof how
alltherelevantvariablesinteractcan pointtosystemmodificationswhichenhance particulatematter removalfromgasstreams.Areviewandanalysisof various perfor-mancemodelsfor filtersandelectronicair cleanerswasdone byLawlessetal.[10].Computationalfluiddynamic(CFD)simulationshaverecently beenmadetoevaluatedustladengasstreamtwo-phaseflow patternsinsideair pollutioncontrolequipment[11, 12].
2.RECENTADVANCESINUNITOPERATIONSFOR AIRBORNEPARTICULATECONTROL
Described belowarethevariousconventionaltechnologiesthathave beendevelopedtoremove particulatematter fromgasstreams.Thecapturemechanismsdescribed
previouslyareexploitedintheseunitsor processes.Eachunitoperationwill betreatedin itsownsection.Theywill beintroduced
withagenericdescription
of the process
andequipment.
Thisisthenfollowed by
adiscussionof specificrecentinnovationsandtechnologydevelopments.Theemphasisinthissectionis onthedesignandoperationof the physicalequipment.Section3discusses particulateemissioncontrolfroma process perspective.
Figure2 is agraphicalguideline,mappinga suggestedtreatmentmethodfor a particle-ladengasstreamdefined byadesired particulateremovallevelandoperat-ingfiltrationvelocity[3].Thereis aroughmonotoniccorrespondence betweenthefiltrationefficiencyandthe pressuredropacrossthefilter for agivenflux.
2.1.CyclonesThegeneral principleof inertialseparationisthatthe particulateladengasisforcedto
changedirection.Asthegaschangesdirection,theinertiaof the particlescausesthemtocontinueintheoriginaldirectionand beseparatedfromthegasstream,exploitingtheinertialseparationmechanism.
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Figure2.Unitoperationmapfor airborne particulatetreatment,with parametersof filtrationefficiencyandfiltrationvelocity.Adaptedfrom[3].
Cyclones,wherethegasisforcedtospinina vortexthroughatube,arethemostcommontypesof inertialseparators.Atypicalcycloneconfigurationis showninFig.3.
Inertialseparatorsarewidelyusedfor thecollectionof medium-sizedandcoarse particles.Their relativelysimpleconstruction,low pressuredropsandabsenceof moving partsmeanthat boththecapitalandthemaintenancecostsarelower than
for alternativemethods.Ingeneral,however,cycloneefficiencydropsif thefinescontentof the particulatematter issignificant.Theyaretypicallyusedas precleanersupstreamof other devicestoreduce particulateloadingsandtoremovelarger,abrasive
particles.Conventionalcycloneseparatorsareseldomcapableof thenecessaryremovaleffi-
cienciesfor anentire particlesizerangeof anindustrialgascleaningapplicationunder presentPM10guidelines,if designedaccordingtostandardelementarycyclonetheo-ry[13].Thedeviation between predictionand performancearisesfromthe presenceof secondarycurrentswithinthecyclone body,whichdisturbthe predicted process
of separation.Primaryflowcharacter can berestored byattentionto thedetaileddesignof thecyclone,includingthegeometryof theseparationchamber,the positionof openings,useof flowguideswithinthecyclone,thedimensionsandthegeometryof thehopper, bleedingand bypassingof thegas,useof multicyclones,andmeansfor dustagglomeration.Alternatively,a 'duststrand'cyclonecan bedesigned,exploiting
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Figure3.Simplifiedschematicof acyclone.
thesecondaryflows(Deanvortices)whichattainhigher localsolidsconcentration,enhancing particleremoval[14].Someinnovativemodificationshave beenmadetoconventionalcycloneunits.The
applicationof anexternalelectricfieldtoacycloneunitfilteringlowresistivitysilicaroughlydoubledthecollectionefficiencyof particleslessthan5Amindiameter atlowflowrates[15].Built-in particulatematter removalcapabilitywasconsideredwiththedesignof acyclonicsuspensioncombustor for the burningof pulverizedcoalor coal-water slurry[16].Cyclonicseparatorsarealso beingconsideredasdieselsootcollectors.Aunitdesigned byKudosCorp.intheUK involvesspinningagasthrough
a tubewhilealsospinningthetubeitself,toseparate particlesdownto0.11 /,Lm.Thissystemexploitssecondaryflows(Rankinevortices)andoperatesatrotationratesof 60000r.p.m.[17].It hasyetto befieldtested.Acompetingsystemmakesuseof a sprayelectrodewhichcharges(presumably,neutralizes) particlessothattheyagglomerateandarecaptured byacyclone.Between75and90%of the particulateemissions,downtodiametersof about0.6>m,werecaptured bythissystemduringtestswithaPeugeotdieselengine[18].
2.2.Electrostatic precipitators(ESPS)
ESPisa particlecontroldevicethatuseselectricalforcestomove particlesoutof theflowinggasstreamandontocollector plates.The particlesaregivenanelectriccharge byforcingthemto passthroughacorona,aregioninwhichgaseousionsflow.Theelectricalfieldthatattractsthecharged particlestothewallscomesfromelectrodesmaintainedathighvoltagein thecenter of theflowchannel.Thisarrangement
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is shownschematicallyinFig.4. Chapter 10of [4]containsa number of goodillustrationsshowingtheconstructionandconfigurationof entireESPunits.
Oncethe particlesarecollected,theymust beremovedfromthe plateswithout
anyappreciablereentrainmentintothe
gasstream.Thisis
usuallyaccomplished byknockingthemloosefromthe plates,allowingthecollectedlayer of particlestoslidedownintoahopper.Some precipitatorsremovethe particles byintermittentor continuouswashingwithwater.
ESPshaveenjoyedverywidespreadusefor fine particulatematter removalappli-cations.Theyareamature,establishedtechnologyandthemovefor innovationintheESPareaappearssomewhatlessurgentthanelsewhere. Nevertheless,thereisstillsignificantandinterestingactivityfor updatingESPtechnologyfor theimprovedcollectionof ultrafine particulates.Quiteextensivereportingonrecentwork appears
regularly[19, 20].Inviewof the presentlargenumber of ESPinstallations,aconsiderablemarketexistsfor retrofitopportunities.Thetighteningof emissionsstandardsfor S02and NOxandsub-100 >m particulatematter mayimpactonthecapabilitiesof theESPinfrastructure.Anoverviewof someof theissuesfacingtheESPuser community,andanintroductionto someof the basictypesof retrofitoptionswasgiven byOffenandAltman[21].Beyondtheneedtoconditionthefluegas,typicalupgradeoptionsincludeenlargingtheESP,sectionalizingtheESP(dividingfluegas passagesintoagreater number of segmentswhichcanindividually beoperatedatmoreoptimumlevels),spacingthe
collector platesfurther apart,implementing processcontroland/or improvedrappingandcollectionequipment[22].Twoindependentstudies,focussingonthetechno-economicsof ESPusefoundthatwiththeincreasinguseof high-resistivitycoals,ESPscannotcompetewith pulse-jetfabricfilter systemswhen particulateemissionsregulationsallowonly0.01lb/MBtu[23,24].
Figure4.Schematicof atypicalelectrodeandcollector arrangementfoundinsideanelectrostatic pre-cipitator.
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Anumber of recent papersdetailspecific physicalmodificationstoESPstohandlehigh-resistivityflyash.CasestudiesarediscussedwhereexistingESPinstallationswererebuilttohouselarge plateheightsandwider platespacings[25].TheESPcan
be placed
downstreamof anon-leaking,high
dustloadgas-gas
heater (withwater astheheatexchangemedium)toreducethegastemperaturethroughtheESPtothe90-100°Crangerather thantheconventional130-140°Crange[26].Pilottesting
hasshownthatthedecreasedtemperaturedecreasestheelectricalresistivityof thedust,improvingcollectionefficiency.Hitachihasintroducedtwonewconfigurationsfor ESPs[27].ThemovingelectrodeESPhasthe platessectionedintoshort panelsthatcirculatelikea verticalconveyor belt.Thedustis collected byrotating brushesinahopper zonewherenogasflowsand particulatematter reentrainmentisminimal.Theyhavealsodevelopeda 'saw-edged'wirethatshowssuperior staticdischargecharacteristics,usefulfor
rapidlychargingsubmicron
particulatematter whichismore
abundantwhenthe boiler fuelis oilinsteadof coal.Operatingexperiencewithintermittentenergizationof theESPtosuppress back coronaandthusincreaseESPefficiencyfor thecaptureof high-resistivity particulatematter wasreported[28,29].Exampleswerecitedongasstreamtreatmentfromcoal-fired boilers,oil-fired boilers,Kraft pulp boilersandiron-oresintering plants.
Anoveltwo-stageESPwithanelectrostaticagglomerator betweenthestageshas beentestedatthelaboratoryscale[30].AquadrupoleACelectricfieldisappliedtotheremainingfinesafter thefirstESPstage,inducingoscillatorymotionandelectrical
polarization,whichhave beenshowntoincreasesubmicronmeandiameters by400%andincreasecollectionefficiencyfrom95to98%.Asystemhas beendesignedwithflowdiversionduringrappingtominimizefinesentrainment[31].Costestimatesfor thistechnologyshowthatthistechnique provides benefitsfor emissionslimits
below50mg/Nm3.Specialhorizontalstripcollectorswithout baffleshave beenshownto increaseESP performanceonlargeinstallations[32].Seoul-Sharp-CEDhasdevelopedwhattheyterma 'SUPER-ESP'[33].Byseparatingthechargingandcollectingfunctions, bothstepscan bedoneindependentlyina moreconsistentandoptimizedway.Ahigh particlechargecan beimpartedfor anylevelof resistivity,andthenthese particlescan besubjectedtotheappropriateelectricfieldfor collection.Thetemperaturecan becontrolledintheseparatechargingareatomodifytheresistivity.Insteadof anESPwithseverallongconventionalsections,a smaller ESPresultsfromthisconfigurationwhena number of chargingandshortcollector pairsareused.For low-resistivity particulatematter thisdesigncan provideaunitaboutone-thirdthe
physicalsizeof aconventionalESPandthesizeisfurther reducedto one-sixthfor high-resistivity particulatematter.
Theelectricalnatureof precipitatorsmakethemespeciallysuitablefor digitalcon-trol.A recentexpertsystemcontroller employingfuzzylogicallowssomeof themoredifficultoperationsto beruninamoreoptimizedfashion,suchasdiagnosingfaults,start-upandshutdownroutinesaswellascontrollingtheoperatingefficien-cy[34].Fieldtestinghasshownsignificantemissionsreductionsaswellasloweredenergyconsumption.Other typesof controllersfor spark rateandspark anticipationcan better enableexistingESPunitstohandlefluegasandflyashvariabilityin anenergyefficientmanner [35].
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WetESPsystemscontinueto playa keyrolefor specialized particulatematter removalapplications.For certainlower temperatureapplications(belowthedew-
point)onlywetelectrostaticsystemscan beused.Dissolvingchemicalagentsinthewash
liquidcan
providea meanstofixunwanted
gaseouscomponentsalongwiththe
suspended particulatematter [36].InJapan,MitsubishiHeavyIndustriesLtdhavedevelopedandtesteda 'highvelocity'wetESP,capableof workingatfaceveloci-tiesof 10m/s,therebyallowingitsinstallationwithinexisting plantconfigurationsinsomecases[37].WetESPsarewellsuitedtoapplicationssuchascoal-firedmag-netohydrodynamicsystemswherethefinescontentinthefluegasissubstantial[38].Asa retrofitoptionfor wasteincineration plants,wetESPshave beenaddedafter awetscrubber totreat particulatematter andacidgas.AunitknownastheSonicKleenwetESPsystemconsistsof a bundleof hexagonal(tosavespace)downflowtubesmadeof a
conductingsteel
alloy,whichcontaindischargeelectrodes[39].Condensed
liquidsfromthegasstreamirrigateandhelpcarry particulatestothe bottomof theunit.Variousinnovationshave beenmadeto addressspecificapplicationneeds.The
final particulatematter cleanupfromwoodfired boilersis oftendonewithESPssincetheflyashhasa lowresistivity.Rappingfor suchsystemsis of paramountimportanceasresinsandunburnedmaterialmay be presentonthecollector surface,andanysparkingcouldcauseit toignite.Sonichornswereinstalledandtested,replacingrappersfor cleaning precipitator internalsfor woodfiredapplications[40].Emissionsof particulatematter withsonichornrappingwereshowntohavedecreased.Anoptionalwayof treatingdieselsootis withanelectrostaticagglomerator [41].Acorona-less pipe-typeESPisusedtocollectandagglomeratedieselsoot particleswhichgrowintolarger particlesandmay becollecteddownstreamwitha simpleinertialdevice.
Anumber of theoreticalmodelshave beendevelopedrecentlytocharacterizeESP behaviour.The performanceof existingESPscan beenhancedwithimprovedfeedstreamdistributionthroughtheir internalvolume.ACFDstudywasconductedtohelpdesigna flowdistributor for ESPsusedinthecementindustry[42].Thedesignrecommendationswereusedto bringadry-processcement plantintoregulatorycom- plianceinIndiana,USA.Ona moremicro-scale,a CFDstudywasmadeonionicwind,whichisthesecondaryflowthatdevelopsunder massconservationrequirementswhenionizedgasdriftstowardsthecollecting plate.It wasfoundthationicwindeffectsaresignificantfor superficialflowvelocitiesunder 0.6m/sanda collectionefficiencyreductionof over 10%mayoccur whenthesuperficialflowvelocityfalls
below0.2m/s[43].Conditioningthecarrier gasoftenincreasesthefeedstreamhumidity.Theinfluenceof humidityonthechargedensityandtheelectricfieldina
precipitator wasmodelledandsolvedwithgoodresults[44].
2.3.FabricfiltersFabricfiltersremovedustfromagasstream by passingthestreamthrougha porousfabric.Dust particlesforma porouscakeonthesurfaceof thefabric.Itisnormallythiscakethatactuallydoesthe bulk of thefiltration.
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Themanner inwhichthedustisremovedfromthefabricisa crucialfactor inthe performanceof a fabricfilter system,sothatfluxlossesfromexcessive pressuredropwitha thick cakeare balancedagainstdustleakageoccurringwithtoothina cake.
Fabricfilter systemsarefrequentlycalled baghouses,sincethefabricisusuallymountedincylindrical bags.Thetwomostcommon baghousedesignsarethereverse-air andthe pulse-jettypes.Thesenamesdescribetheaffiliatedfabriccleaningsystem.
Therehas beenanincreasingrecenttrendtowardsselectingfabricfiltersfor newequipmentinstallationsandupgradesinexisting plants.Improvementsinfabricfilter
performance,simplicityof operationandlowcapitalcosthave beenmotivatingfactors.Themostsignificantinnovationshavecomeintheareaof fabricmaterials.
Sincethelate1980s, baghouseinstallationshave beguntoappear featuring pulse-jetfabricfilters(PJFFs).Thesesystemsarequicklyreplacingconventionalreverse-gas-
cleaned baghouses(RGB),as themostwidelyusedfabricfilter unit.PJFFsarecharacterized bytheir useof periodicshort, powerful burstsof air tocleanthe bags,allowingtheunitto beoperatedattwotothreetimesthefacevelocitiesof thereverse-gas-cleanedsystems.Ingeneraltheyexhibitimproved pressuredropcharacteristicsandcan beretrofittedintoESPcasings.SeeFig.5.
Figure5. Schematicof a pulse-jetfabricfilter baghouse.Thefilter bagsontheleft-handsideareshowninfiltrationmodeandthoseontheright-handsideareshowninthe pulse-jetcleaningmode.
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Athree-partseriesof paperswas publishedto provideanoverviewof the per-formanceandoperatingexperienceswithPJFFsfor coal-fired boilers,aleadingap-
plication[45-47].ExtensivedataonvariousPJFFinstallationswere provided.In
general,theseunits
operate below0.03lb/MBtu
(0.054mg/Kcal)whichistheUS
EPA particulatematter emissionsstandard.WovenfeltssuchasDralonT8,Rytonand Nomexwererecommended bagmaterials.Teflon bagshaveshownsomediffi-cultywith particulatematter collection, possiblyowingtothelargefibrediameters,despitetheir abilitytooperateinhotter andmorecorrosiveatmospheres.Part2 of theseriesreportedon pilottestsfor fossilfuelinstallations,includingoil-fired boilerswithuniformlygoodresults.Higher frequency bagcleaningwasrequiredfor highashcoals.Part3 of theseries providesaneconomiccomparisonwithESPsandRGBs.ESPscouldonlycompetewithPJFFsystemswithlow-resistivityfeeds.ComparedtoRGBs,thePJFFsystemsoffer a 10%lesslevelizedcostover a 30year plantlifeaccordingtothisanalysis.TherearesomecommercialPJFFsystemsavailable.TheOPTIPULSEsystemfromABBisaimedatsteelmakingapplications[48].TheHosokawaMicropulsystemwasdesignedwithinletgasdiffusersto provideuniformface pressuresover thefilter bagsurface,givinganoverallimprovementin performance[49,50].Similarly,filter cagedesignsmadefrom perforatedmetalsheet,rather thanwiremesh,subject pulse-jet
bagstolessstressand prolongtheir lives[51].Baghousesareoftenemployedtocollect particulatematter fromsomeof thefeed
conditioning processesdiscussedinSection3.3.Filter bagsmadefrom3M Nextel
312wovenalumina/boria/silicaceramicfibrehave beeninstalledintheSNRB pro-cessandhave beensuccessfullytestedattemperaturesupto590°CagainsttheEPAstandards[52,53].
Thefabricmaterialsthemselvesareof coursethesubjectof considerableresearch.Theextramechanicaldemands placedon pulse-jetsystemsmakeglass-basedfilter media pronetofailure.Asaconsequenceof this,therehave beennumeroussyntheticfeltsdevelopedfor someof theseapplications,suchasindustrial boilers,combustingfluidized bedsandincinerators[54].Polytetrafluoroethylene(PTFE)or Gore-Texefilter materialshave beendeveloped.Someearlywork showsthatthefavourable
PTFEsurface properties permiteasydustlayer removal,andoperationattemperaturesupto 260°C.Fine particulatematter still posesa problem,with50%escapeat0.86 jum[55].Pulpand paper bark boilers presentspecial problemsas thesegasstreamscancontainincandescent particles.Temperatureresistanceupto600°Cis
providedwithBiothermicastainlesssteelfabricfilters.Afault-free4-year testwasconductedatanindustrialsitewiththismaterial[56,57].
Ona morefundamentallevel,therehave beenstudiesconductedonsomeof thedetailedfabric properties.A parametricstudywasconductedontheeffectsof yam
processingandweavingvariablesonthefiltrationefficiencyof wovenglassfabrics.
It wasfoundthat processingconditionswhichkeeptheglassfilamentsintheyarn bundleseparated producedthe best performance[58].A number of commerciallyavailableconductivefabricshave beendesignedtoreduceelectrostaticchargeindustcollectorswhereflammabledustsare present,suchasinflour mills,woodworkingoperationsand polyvinylchloridemanufacturing[59].
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Analternativetothefilter bagisthefilter 'box'or cartridgefilter.Theseunitsaremadeof stiff corrugatedfilter materials,whichcanoffer muchhigher filter surfaceareacomparedto baghousesof thesamefootprint.Manyof thetechnicalcapabilities
aresimilar to baghouses, buttheir designmakestheminherentlylesscleanable.Theyareratedfor particulatematter loadingsof about25%of thatfor baghouses[60].Owens-ComingFiberglashave beendevelopingavanadium/titaniumcatalystcoated
wovenglassfabricfor simultaneous NOxand particulatematter control.Over 90% N0?removalhas beenobtained, butmanyoperating parametersrequiredtoachievethisleveleconomicallyhaveyetto beresolved[61,62].
Fabricfilter systemscan beelectrostaticallyenhanced.Anearlystudyshowedthatanelectricfieldcanalter thedustdeposition patterninsidea bag,givingalower pressuredrop[63].A number of analyticalandexperimentalinvestigationsof this
phenomenaarereviewed
byRaoandMurthy[64].A portableelectrostaticcartridge-typefilter hasrecently beendeveloped,for applicationssuchascookingodour controlandsmoketreatment.Over 98% particulatematter capturehas beenachievedatdiameters between0.01and1.0 however facevelocitiesmust belessthan0.1m/s[65].
2.4.WetscrubbersIntheseunits,a particleladengasstreamissubjectedto a sprayof liquidwhichcontactsandcapturesthesolidmaterial.Avarietyof geometriesanddesignsareavailablefor implementingthistechnique.Themechanismsof impaction,interceptionanddiffusionall playa rolein particulatematter captureinwetscrubbers.
Condensationscrubberscan beconsideredto bea subclassof wetscrubbers.Incondensationscrubbers,usuallysupersaturatedwater vapour is broughtintocontactwith particulatematter andliquidcondensationoccursonthesurfaceof thesolids.Thiscancreatea nucleationsitefor agglomerationwithother wetted particles.Themassof the particlesgrowsinthiswayandtheycan bemorereadilycollected byinertialimpactionor evengravitysettling.Thethermophoresismechanismis alsoexploitedincondensationscrubbers[9].
Wetscrubber technologiescontinuetoenjoyfavour for particulatematter removal,especiallyincoal-fired power generationapplicationswherethefluegasalsocontainsS02and NOxandcan beremovedsimultaneously bythescrubbingliquid.Con-ventionalunitsincludeventuriscrubbers,mechanicallyaidedscrubbers, pump-aidedscrubbers,wetted-filter typescrubbersandtrayor sievetypescrubbers.Anoverviewof recentwork inthisfieldis providedinan NTIS bibliographicdatabase[66].SeeFig.6.
Somerecentdevelopmentsinwetscrubbingequipmentareintheareaof rotaryor centrifugaldesigns.Onesuchsystem, basedonaConfinedVortexScrubber (CVS),for
fine particulateremovalfromcombustionfluegaseshas beendevelopedandconsistsof acylindricalvortexchamber withmultipletangentialfluegasinlets[67].Water isintroducedintothechamber andis confinedwithinthevortexchamber bytheextremelyhighcentrifugalforcesgenerated bythegasflow.Theconfinedwater formsalayer throughwhichthefluegasis forcedto bubble,leadingtocollection
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Figure6.Componentsof astandardventuriscrubber.Theoutletisoftenconnectedtoamisteliminator wherethewater andgasstreamsareseparated.efficienciesinexcessof 99.5%for fineflyashof diameter 3gmand98%for 0.3¡Lmdiameter particles.A commercialunitknownas theRotorfilterTMmakesuseof scrubbingwater inconjunctionwitha seriesof rotatingairfoils,arrangedsothatthetwostreamscarryingtheliquidandsolid phasescontacteachother atrightangles.Inthisway, particulatecaptureoccursinrecirculationregionscreated bythechevronshapedspokes[68].Theseunitsaredesignedfor smallindustryandcanhandle
between50and500m3gas per minute.Upwardsof 99%of particulatesat0.25diameter can berecovered.Asystemdesignedfor the power industriesemploysa
jet bubblereactor andvesselsmadefromfibreglassreinforced plasticstowithstandthecorrosiveelementsinthestreams[69].DownstreamfromanESP,thisscrubber
wasabletoremoveupwardsof 90%of theescaping particulatematter whilealsoachievinggoodS02control. Newdevelopmentscontinuetooccur withventuriscrubbers.Aspecialintegrated
systemhas beendesignedwitha two-fluidnozzlewhichcan becontrolledtoenhance particleremoval,aided byimpingement platesinthevessel[70].Another suchsystem,aimedatacidgascontrolwhichscrubs particulatesaswell,isintegratedwitha steamstripper toremoveandseparatesaleableS02andVOCs[71].Amulti-stagedsystemusinga saturatedvapour chamber to aidin thenucleationof water-wettablesub-micron particulatematter canachieve99%removalat0.155 >m,withhighturbulence
contributingto particlecaptureatthescrubber walls[72].Somerecentwork has beencarriedoutontheelectrificationof wetscrubbingsys-tems.Anionizingwetscrubber has beendevelopedtoremovefine particulatematter downto0.05itm,whilesimultaneouslyremovingacidgases[73].Itsmainareaof applicationiswasteincineration.Theunitcombinesthe principlesof wetscrubbing
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andelectrostatic precipitation,chargingandagglomerating particulatematter withsubsequentcollection byinertialimpactionandimageforceattractionwithinanirri-gated packed bed.Ascrubber withoppositelychargedrotating brushesdownstream
of anionizingatomizer toremove particulatematter is presentlyinthedevelopmentstage[74].Thisdesigntargets particulatematter below5ttmdiameter,andcanoperateatcomparativelylowliquidadditionrates.Treatmentof metalfumefromahazardouswasteincinerator inanionizingwetscrubber wasinvestigated[75].Col-lectionefficienciesrangedfrom22to71%andweregenerallyhigher for lessvolatilemetals.Afundamentalstudyhasmodelledacomplexinterdependenceof theappliedfield,the particlechargeandthedirectionof thefieldrelativeto particlemotionfor electrifiedwetscrubbers[76].Additionally,afundamentalstudyexaminingtheinflu-enceof surfaceelectric propertiesof spraydropletsand particulates,inconjunctionwithsurfactantadditionfor dust
suppressionhas beencarriedout
[77].Themostim- portanteffectfor enhanced particulatematter capturewasanelevateddropletchargefor cationicdropletsolutions.Somerecentwork hasaddressedsector-specificwetscrubbingneeds.Mistelimina-
torsusedinfluegasdesulfurizationareexpectedtohavesomedifficultycomplyingwithanticipated0.002lb/MMBtu(14mg/Nm3)emissionsregulations[78].It has
beenshownthathorizontalflowconfigurationscanupgradethe performanceof sys-tems,whichmayneedtoremoveupwardsof 99.5%of PM10dust.Atwo-stagescrubber designedfor thealuminumindustryhas beenshowntoremoveover 99%of
particulatematter aswellasHClandmorethan90%of
C12fromaluminumreduc-
tioncast-housefurnaceoffgas[79].Irrigationwithchemicalcleansingagentsallowscrubbedmaterialsto berecycledintothereduction process.Finally,a lessrecent, butrarelyimplementedtechnologyis thatof counterflow
inertialimpactionwetscrubbers[5].Anearlystudyfor thecollectionof alunitedust(analumino-silicate)hadtwocollidingaxisymmetricdustygasstreams,sprayedwithfluidattheimpactionzone.Decelerationof the particlesandturbulentmixingattheimpactionzone bringaboutagglomerationof the particulates,wherebytheydropoutof thestreamandcan beremoved[80].
2.4.1.Condensationscrubbers.Condensationscrubberscan beconsidereda sub-classof wetscrubbers,althoughtherearekeydifferencesinthemechanismsemployedtoremove particulatematter.Inthecaseof condensationscrubbers,the particlestravelinavapour saturatedgasstream,wherevapour condensesontheir surfacesandactsasanagglomeratingagent.Onesuchdesign,for thetreatmentof sub-0.25itm particulatematter frommunicipalwastewater incineratorsis documented[81].Existingwetscrubberscan beretrofittedtooperateinthecondensationmode.Asimilar designfor municipalwasteincineratorsmakesuseof fluegasmoisturemixedwitha coldgasstreamresultinginfluxforcecondensation
scrubbing[9].
2.5.Granular bed filters(GBFS)In ananalogousfashionto wetscrubbers,a particleladenstreamcan be passedthrougha bedof solidmaterialwherethe particulatematter iscaptured.The bedcan
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bestationary,movingor fluidized.Thecollector materialtypically possessessomefavourablesurface propertiestoenhancecaptureof the particulatematter.Granular
bedfiltersareoftenusedwhenwastewater problems posed bywetscrubbingsystemsare
unacceptable,suchasfor fluorinecontrolinsomealuminum
plants.Fluidized
GBFsarecurrentlyunder considerationfor hotgascleanupapplications,especiallyasanalternativetoceramiccandlefilterswhichhavehada troublesomedebut.Are-centstudyhasfoundthattheeconomic performanceof GBFscomparesfavourablytocandlefiltersfor coal-fired power generationfacilities[82,83].Theseunitsareme-chanicallysimpleandrequirelessfine-tuningandmaintenance.Themovingcollector
bedhassome by-productvalueandalsoeliminatestheneedfor costlyfilter mediacleaning.Morethan97%of flyashcan beremoved byGBFsata facevelocityof 1.6m/s(basedonthestandpipecross-section), buttheyareknowntohave problemscollecting particulatematter under 2ttm.Atfacevelocitiesover 4m/s,thecollectionefficiencydropstoabout80%[84].MovingGBFshavealso beeninvestigatedcombinedwithelectrostaticenhancement.The basicunitdeveloped bytheCombustionPower Co. performedwellfor particulatematter over 2 >m.Variousfieldstrengths, bothunder ACandDCmodeweretested.TheACenhancementat75Hz producedaslightoptimum.DCoperationalsoshowedvery promisinginitialresults, butitsimplementationisconsideredto beless practical[85, 86].Atlowfacevelocities(0.11m/s),upwardsof 98%of 0.5>mflyashcould
becollected.Theefficiencydropsoff to50%atfacevelocitiesnear 0.7m/s.Anovelsystemhas beendevelopedwitha fluidizedGBFexitingacrossa metal
filter screen[87].Asketchof theunitis showninFig.7. Thescreensurfacecan becleaned bymomentarilyinterruptingthegasflow.The pressuredropinthissystemislow,althoughmaterialfiner thanabout1.5 pmisdifficulttocapture.Thissystemallowsrelativelyhighfacevelocities,over 2.5m/s.Therearea fewinstanceswhereGBFsystems provideagood particulatematter
removalsolution.Mosttraditionalair pollutioncontroldevicesareineffectivefor collectingsubmicronmetalfume,whichoftenarisesin wasteincineration.Oneapproachhas beentotestvarioussorbentsina fluidized bedfilter [88];another has
beentouseactivatecharcoal packed beds[89].
Anumber of fundamentalstudieshave beenconductedrecentlytofurther theunder-standingof granular bedfilters.Finematerialwasfoundto bemorereadilycollectedatelevatedtemperatures[90].Reynoldsnumber effectswereconsideredinanother study[91].
Sometimesgranular bedfiltersarereferredtoasdryscrubbers, butmoreoftendryscrubber meansa somewhatsimilar, butdifferenttypeof unit.Anumber of systemsexistwherethestreamdustmay beremoved, butthena sorbentisintroducedfor NOxand/or SOxremoval.Thiscreatesa needfor subsequent particulatematter removalfromthegasstream.Inviewof this,thesorbentmaterialcan bechosensothat
it issufficientlylargeanduncohesiveto beeasilyseparated bylow pressuredrop baghouses.Withanappropriatechoiceof sorbent,thesulfur andnitrogencontaining productcan beusedtomakea number of saleable by-products[92,93].Anelectron beamdryscrubber existsinwhichtheelectronsgenerateOH-radicalswhichoxidizeS02and NOxintosulfuricandnitricacid, precursorsfor makingfertilizers[94].
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Figure7.Fluidizedgranular bedfilter fittedwithmetalscreento preventfilter materialentrainment.Adaptedfrom[87].
2.6.CeramicfiltersCeramicfiltersarerigid barrier filtersconstructedwith poresizesdesignedtoremovefineairbornesolids.The physical propertiesof theceramicmaterialallowtheseunits
to beoperatedunder hightemperaturesandincorrosiveenvironmentsaswellas beingsuitablefor cleaningwithcorrosiveagents.Theyaremadeintwostandardformats:dead-endlowdensity'candle'filtersandmulti-channelcross-flowmodules.
Intherapidlyevolvingfieldof hotgasfiltration,ceramicfilter elementshave provento besuitablefor efficient particulateremoval,withtheabilityto performinharshenvironments.Ceramicmembraneswerefirstusedinthe1940sfor uraniumenrich-ment,yetit took untilthemid-1980sfor particulatematter removalapplicationsfromgasstreamstofirstappear.Generaloverviewsof thisfieldare provided byEggerstedtetal.[95]aswellas byWhiteetal.[96].Recently,ceramicmaterialshavealsofound
their wayintohotgasapplicationsasstructuralfilter components,replacingexoticalloysandsimplifyingdesignapproaches.Anumber of differentceramicfiltrationde-vicesarecurrentlyavailable,eachwithadvantagesanddisadvantages.Thesedevicesincludeceramiccrossflowor ceramicmembranefilters,ceramicfabricfilter bags,and porousceramicfilter tubesor 'candles'.Inaddition,thesedesignsareavailablein
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differentceramicmaterials,eachhaving propertieswhichmay or maynot besuitablefor agiven processapplication.
Despitetheroughly40%higher cost per unitfiltrationareacomparedto bagfilters(1991),ceramicunitsaregaining popularity[97].Inadditionto benefits previouslymentioned,theycanalsohandleheavydustloadingsandfacevelocitiesupwardsof 3cm/s,comparedto about1.5cm/sfor fabricsystems.Providedthatthesystemselectediscleanable,theunitlifecan beseveraltimeslonger thanwithother materials.
High-efficiency particulateair (HEPA)filtershave beenin existencefor over 50years.Theyaretypicallymadeof glassmicrofibresandareusedfor veryhighefficiencyremovalof submicron particulatematter.HEPAfiltersaresuitablefor applicationswhereaveryhighlevelof air purityisrequiredor for theremovalof hazardous particulatematerials[98].
2.6.1.Candle filters.Figure8 showsa schematicunitwhereceramiccandlefiltersareusedtoremove particulatematter fromagasstream[3].Here,thefilter mediumis providedin theformof long,hollowtubesor 'candles',closedat oneendandhungverticallyfromasupport platesothatthegas passesfromtheoutsideinwards.Adustcakeaccumulatesontheoutsidesurfaceof thecandleandiscleanedatregular intervalswithastrong pulseor jetof gassentfromtheinsideoutviathe pulsenozzles.
Therearetwocommontypesof filtrationmediausedinceramiccandles.Thefirstisahigh-densitysinteredor bondedgranular siliconcarbide(SiC).Theother type
Figure8.Simplifiedschematicof aceramiccandlefilter unitwith pulseair cleaning.
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is primarilyalow-densityalumina(ash03)intheformof bondedfibres.Thelow-densityunitsshowlessresistancetoflow,areless pronetothermalshock andarelessexpensive[99].
Themostattractivefeatureof ceramiccandlefiltersistheir abilityto performgascleaningathightemperatures, presentlynear 1000°C.Thedemandfor hotgascleaningisstrongestincoal-fired power plantsusing pressurizedfluid bedcombustion(PFBC)or integratedgasificationcombinedcycle(IGCC) processes.Conventional
bagfiltershavethermaltoleranceswhichrequirethatgasstreams becooled,typically bydilutingthestreamwithatmosphericair.Directhotfiltrationeliminatestheneedfor extra processequipment,reducesthegasvolumefor treatmentandallowswasteheatto berecovered,givinga 2-3%increaseinoperatingefficiency[100].
TheSchumacher SiCcandlefiltersweresomeof thefirsttoundergoextensivetestingin pilot
facilities.In1988atGrimethorpe
intheUK,
a pilot
hotgas particulateremovalsystemusingceramiccandlefilterswas builtina PFBCtestfacility[101].EarlytestswereconductedwithSchumalithSC40modelcandles(mean poresize100/tm),as
wellastheDiaSchumalithF40candleswhicharemadewithanadditionalsurfacelayer of aluminafibres.TheDiaSchumalithF40candleswerefoundto besuperior
becausetheywereabletowork inasurfacefiltrationmodeathigher facevelocitiesandrequiredlower stressesfor dustcakedetachment.TheF40candleswereusedinmostsubsequentwork atGrimethorpewheretheygave promisingdustremovalresultsover 800h testsconductedat850°Cand10 bar pressure[102].Further testingatGrimethorperevealedthatextendedusewithcold
pulsecleaningcausedthecandlesto
liftanddescendrepeatedlyresultinginfractures bothinthecandlesandtheir sealinggaskets[103].Asimilar pilottestwasreported bySchumacher themselves,withover 4000hattemperatures between780and850°C.Attemperaturesabove700°Cmorethan99.999%of all particulatematter wasremoved,withthemost penetrationoccurringinthe0.2-0.4fLmsizerange(cf.Fig.1)[104].
Increasingly,demandingtestingof theDiaSchumalithF40has beenreportedmorerecently.Concernsover performancehavefocussedoncandleintegrityover repeatedhot-coldcleaningcycles.Thestrengthof thecandlewasfoundtodecrease by2.2%over a 4 month periodattestsconductedat 850°C.Athermalshock (temperaturechange)of over 600°Cwasfoundtooccur bynumericalsimulationof thecleaning pulseflowinsidethecandle[105].By1993,newtestshadshownimprovedversionsof theDiaSchumalithF40candles, butstilla recommendationfor hot pulsingwasmadeto minimizetheseverematerialsduty[106].Other testshaverevealedthat
breakageof candlefiltersarosefromthemechanicalstressesassociatedwithliftinganddropping.Specifically,thedeteriorationmechanismsweretheoxidationof SiCtoformcristobalite(Si02),microcrackingandcrystallizationintheglass bondnecksandglass/SiCinterfaceand pittingof theglass bond byCaS04[107].Servicelivesof uptoaboutoneyear could beexpectedfromtheSiCcandlefilters.Thethermalshock
resistanceof theDiaSchumalithF40filterswascomparedtoother SiCcandlesmade byRefractonaswellascandlesfromAsahiGlassCo.madeof cordierite[108,109].Schumacher SiCcandlefiltershave been pilottestedfor hotgascleaningata low-
level-wasteincinerator ata Germannuclear facility,andwerefoundto be promisingwhenthefeedstream particulatematter containsverylittlesubmicronmaterial[110].
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Fibrous,layered,low-densityalumina-silica basedcandlefiltersmade byFoseco(FosecoCerafil2000i)have beentestedfor PFBChotgascleaning[111].Thesetestswereconductedattemperaturesupto740°Candtypicallyupwardsof 99.9%of the
particulatematter wasremoved.Thenominal
poresizefor theseunitsis lessthan
10fLm[3].Althoughnoneof thefiltersinthesetestsfailed,thetesting periodof 340h wasconsideredtooshorttocommentontheir durability.Candlefiltersmadeof ?-cordierite bytheAsahiGlassCo.weretestedonPFBC
dusts[112].Of noteisthatthesecandlesfilter fromtheinsideout,usinga positive pressurerather thansuction.Atcomparable permeationrates,theywerefoundtogivea downstreamdustlevelunder 3 p.p.m.w.,comparedtolessthan1 p.p.m.w.for theSchumacher SiCcandles.TheAsahifiltersweretestedfor over 2000h attemperaturesupto 880°C.Likelyduetotheir quitelarge physicalsize(lengthof 5.8
m)and
beingfastenedtothevesselat both
ends,thethermalshocksrelatedto
the pulsecleaning produceda muchhigher rateof filter mechanicalfailurecomparedwithother candles.Anupdateonthestatusof theAsahicandlefilterswas provided byHigashiandMaeno[113].
Testinghas beenconductedonsurfacetreatedSiCcandles(LayCer 50/5)made bytheIndustrialPumpandFilter ManufacturingCo.(USA)[114].Theyhavea nominal
poresizeof 24ttm,weretestedat870°Candgavea filtrationefficiencynear 100%.Thisstudyfocussedonthenatureof thecake builduponthefilter surfaceandhowdifferentoperatingconditionsrelatedtothe pressure-fluxrelationship.
Westinghousehas
developeda new
housingunitfor candlefiltersandhastestedthe
DiaSchumalithF40candles[115].TheywereexpectedtoreplacetheSiCfilterswithalumina/mullitecandles.A projectsponsored bytheUSDOEis beingconductedtodevelop practicalhotgasfilter designsthatmeettheoperationalrequirementsof PFBC[116].
Theeconomicsand processoptionstoconsider for implementingceramiccandlefilter systemsarediscussed byZievers etal.[117].
2.6.2.Cross-flowfilters.Particulatefilterscanalso bemadefromdensesinteredce-
ramicconstructedinto box-likestructures.Suchdesignsincludeseparate passagewaysfor thefeedandcleanedgaswhicharelinked bythe porousceramicfilter material.Figure9showsa schematicsketchof onecomer of ageneric block shapedceramiccross-flowfilter.Ascan beseen,thisarrangementgivesaveryhighfiltrationareatovolumeratiocomparedtoconfigurationsusedinother technologies.Alltheother
benefitsattributedtoceramiccandlefiltersinthe previoussectionapplytoceramiccross-flowfilters[95].Backflow pulsingisusedtocleanthe particulatematter whichcakesonthe passagewalls.
Theemissionof sootfromdieselengineshas poseda problemfromaregulatory
standpoint.Tomeetthesestandards,andsinceit is not practicalto coolexhaustgasesfromavehicle,various particulatetrapsmakinguseof ceramiccross-flowfilter technology(andother typesof ceramicfilters)have been beinginvestigatedsincetheearly1980s[118-120].The proposedEPAair qualitystandardsfor 1994haverenewedinterestinthistopic[121].
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Figure9.Simplifiedschematicof aceramiccross-flowfilter.Shownhereisthetopcomer of a box-shapedunit.
TheAsahiGlassCo.hasdevelopeda new particulatetrapsystem[122,123].Itfeatures botha cross-flowtypeceramicfilter andreversecleaningregeneration.Thefilter ismadeupof thin plateelementsof modifiedcordierite.Each platehasa rowof sometwodozenopen-end,oval-sectionedchannels.A periodicreverse jetcleaning
bycompressedair injectionremovesthe particulatefromthefilter wallanddropsitintothevessel bottom.It is burned byanelectricheater.Thetrapefficiencyof thissystemrangesfrom88to95%.Thedurabilityhas beenconfirmed by bothlaboratorytestsandfieldtestswith public busesinLosAngeles,USA. NGK InsulatorsLtdalso producea cordieritediesel particulatetrap[124].Recent
attentionhasfocussedoncleaningrequirementsunder specifiedcombustionflowrateswithminimalthermalshock.The NGK unithas beentestedextensivelyon busesinItalyand performedwellin principle[125].Itwasrecommendedthatthecross-flowfilter unit beenabledwithcontinuousfilter loadingcontrol,to bring particulatematter collectionefficiencytoacceptablelevelsfor practicaloperatingconditions.
In NorthAmerica,GeneralMotorsincooperationwithCominghavedevelopeda
cordieritewall-flowfilter for lightdutydieselengines[126].Thethermaldurabilitywastestedanddesignedtoachievearequired120000vehiclemiles( 192 000km),withoutexceedingthe0.13g/mile particulateemissionsregulation.Theuseof Com-ing particulatetrapsonheavydieselequipmentinundergroundmineshas beenshowntoimproveair quality[127].
Inrelatedresearchonfilter regeneration,ithas beenshownthatitis possibleto pro-videa moreuniformenergyinputtoa filter byincorporatingmicrowave-susceptiblematerialsinthefilter bodyandthenusingRF(microwave)energytoinitiatecombus-tion[128].Thismethodgivesimprovedcontrolover thesootcombustionandlower
thermalstresseswithinthefilter.For genericair pollutioncontrolapplications, preliminarycommercialunitshave beenmadeavailable byCeraMem(USA)[129].The particulatematter removalabilityisnear 100%withnominal poresizesfrom0.5to0.004 >m,dependingonthesurfacemembranecoatingused.Asetof 36moduleseachwithexternaldimensions
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of 12x 12x30cmandover 3.4m2filter areawasabletocleansatisfactorilythe0.28m3/sfluegasat120°CfromanEPRI baghousefacilityover a periodof 1100h.Testingonhotgasstreamsfromamagnetohydrodynamic(MHD) power generationcombustor revealedsomeunit
sealing problemsalongwith
unsatisfactory pressuredropsandfacevelocities[130].Ceramiccross-flowfiltersfor MHD plantswere,however,stillconsideredto bea promisingtechnology.Arecentadvancewastheuseof acatalyticvanadiacoatingfor simultaneous NOand particulatematter removalfromhotgasstreams[131].TheUSDOEisalsoinvestigatingacatalyticmixedmetaloxidecoatingonceramiccross-flowfiltersfor integratedS02, N0?and particulatematter removal[132].
Across-flowceramicfilter unithas beenunder development byWestinghouseandCoorsCeramics[133].Itunderwenttestsat900°Cfor periodsof 1000hwithvarious
typesof PFBC
flyash.In
general, particulatematter removalwas
quitehigh, but
posttestinspectionrevealeda number of materialflaws.Whenthemeansizeof theairborne particulatematter fell below5tim,theflowresistancefromthedustcakeandtherequiredcleaning pulseintensityincreasedmarkedly.
Anew product byCeraNovaandSpecificSurfaceCorp.usesa novel powder pro-cessingmethodtotailor ceramiccrossflowfilter elements[134].Theyemploya'three-dimensional printing' process,wherebyfunctionalceramiccomponentsarecre-ateddirectlyfromcomputer generatedmodelstructureswhichcontrolafabricatingunitwhich'prints'themonolith,layer bylayer.Thecompositionwithineach build-
planecan beselectivelycontrolled byvaryingthecompositionof powder andsus- pendingfluid.Anink jet printingheadisusedtometer thematerials.Inthiswaythemicrostructurecan becontrolled bytherelativeinfluenceof cohesiveandcapillaryforcesof thematerialsintroducedtoeachlayer.Functioningfiltershaveyetto bemadeinthisway, butsamplemonolithshave been preparedinthelaboratory.
3.RECENTPROCESSINGINNOVATIONSIn additiontoimprovementsmadeonair pollutioncontrolequipment,therehas
beenmuchrecentattentiongiventoaddressingairborne particulateemissionremovaland/or reductionfromanintegrated perspective.Researchanddevelopmenton pro-cessmodificationsaimedat producingahigher qualitygasemissionarediscussed
below.
3.1.HybridsystemsTheneedfor simultaneouscontrolof particulatematter andtoxicgases,or even
particulatematter of variablesizeandcharacter often,resultsintheuseof hybrid
systems.Thesesystemscompriseeither asingleunitor a processinwhichvarious particulatematter collectionmethodsareemployedin seriestoobtainsignificantlyreducedsolidsemissions.
For the purposeof thistreatiseahybridsystemwill beconsideredto beasingle physicalunitwhichcombinestwoor more particulatematter removaltechnologies.
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Atechnologydeveloped byEPRIintheUScombineselectrostatic precipitationwithfabricfiltration.ThissystemisknownastheCompactHybridParticulateCollector (COHPAC)[135].The baghousefollowstheESP,either inseriesor actuallyinside
theESPhousing.Ina COHPACsystem,theair leavinga power plantflowsfirstthroughanESP,thenthrougha baghouse.TheinitialESPtreatmentsignificantlyreducestheconcentrationandoftenimpartssomeelectricchargeto the particlesenteringthe baghouse.Thecharged particlesaremoreliabletorepeleachother aswellasthefabricfilter material,sothatthelevelof porecloggingis reducedand
bagcleanabilityis increased.For thesereasons,thefacevelocityintheCOHPAC baghousecan befour toeighttimeshigher thaninconventionalinstallations.Inturn,theincreasedthroughputallowsa muchsmaller physicalunitsize[136].Anumber of pilotandcommercialscaletestsof theCOHPACsystemhave beenmade.The
particulatematter emissionrequirementsweremetsatisfactorily, but baglifeconcernswereraised, perhapsowingtothecomparativelyhigher facevelocitiestowhichthe bagsaresubjected[137].
Afewmiscellaneoushybrid-typetechnologieshave beendeveloped.A processandapparatusfor treating particulatematter andacidgasinoneunithas been patented[138,139].Here,theexhaustgas(i.e.fromsintering plantsor fuel-fired plants)isfirstde-dustedinacyclonestage,thenafter carefullycontrolledmoistureaddition, passedtoanESPstagewherethe particulatematter collectedis humidified butessentiallydry,thusallowingit to beseparatedfromtheacidgas.A smallindustrialmodule
has beendevelopedwhichcombinescentrifugationandwetscrubbingfor particulatematter removal,followed by passingthegasstreamthroughactivatedcarbonsponge bagsfor demisting[140].Thedemistingstepcanincludeacidgasfixationand/or odour removal.
3.2.Feedsamplingand processcontrolTheelectricalnatureof ESPsmakesthemwellsuitedfor implementingon-linecontrolsystems, principallyfor power efficiency.Someof thesecontrolstrategieshave beennotedinSection2.2.On-linemonitoringof emissionstotheatmospherefor regulatorycomplianceisa differentmatter andsometechnologiesfor this purposehaverecently beendeveloped.
A prototypeESPdevicewasdevelopedcontaininga total-reflectionX-rayfluores-cencespectrometer (TXRF),intendedtodetectheavyelementsandmetals[141].Atflowratesunder 1.31/min,essentially100%of submicron particulatematter is col-lectedandtheconcentrationof HAPsinthestreammay beaccuratelymonitored.Anon-lineair samplingapparatushas beendevelopedfor measuringVOCconcen-trationsingasstreams[142].Twoinitialfiltrationstagesremove particulatematter above2.5fLmindiameter,atwhich pointimpactionseparatorsmakesizeclasses be-
low2.5,1.5,0.8and0.32itm.Thecaptured particulatematter canthen beanalyzedfor adsorbedVOCs.Somedeviceshave beendevelopedfor on-linemeasurementof particulateconcentrationsingasstreams.Aglassfibrefilter has beenincorporatedintoagravimetricdevicefor continuoussamplingof particulatesdownto0.011 >minsize.Theglassfibreshavesuperior opticalcharacteristicswhichcan beexploitedfor
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other analyticalmeasurementsandareavailablewiththissampler [143].Similarlyaconceptualdesignhas been patentedfeaturingaseriesof impingingcollectorswhich
provideagasstream particulateconcentrationandsizedistribution[144].Practical
operatingrangeshavenot
yet beenestablished.
TheBHAGrouphavea lineof continuous particulatemonitoringdevicesusingamodulatedLEDlightsignalwhichrespondsonlytomoving particulates,soitremainsunaffected byaccumulationof dustor moisture[145].Theextentof signalmodulationcan becalibratedtodustconcentrationinthegasstream.A primaryintendeduseis in baghouseinstallationsasa monitor for filter bagleaksor failures.Another
potentiallyusefuldevicefor baghouseinstallationsistheHansentekTMspark detector andextinguisher [146].Sparksof diametersdownto0.4itmcan bedetected byinfraredsensorsandanappropriateextinguisher can betriggeredtoeliminatethem.Sucha
systemwouldallowtheintroductionof fabricfiltersto control
particulateemissionsfromwood-fired pulpand paper boilers.Fabricfiltershave beenslowtogainwidespreaduseinthissector duetotherisk of firefromairbornemicro-embers.
Processcontrolsystemshavefounda morelimitedapplicationin particulatecontrolinstallations.TheHarwellLaboratoryinEnglandhas beendevelopinganexpertsystemfor thecontrolof fabricfilters[147].Thestateof theartin thisareaissomewhatrudimentary becausethe primaryoperatingvariable,the pressuredropatsteadystate,is notreadily predictable.Usingon-line pressuredropmeasurements,theflow,compressor pressureand pulse periodscan beadjustedinrealtime,and
earlyresultshaveshown
upto20%
savingsin power consumption.3.3.Feedstreamconditioning
Oftenthe performanceof air filtrationunitscan beenhancedif the particulatematter in thefeedstreamenteringtheseunitsisgivensome preliminarytreatment.Feedstream'conditioning'mayconsistof suchtreatmentsasinjectingadditivesto thestream,irradiatingitor subjectingittoacousticshock.Theobjectivestypicallyaretomodifythesurface propertiestoimprovethe particulatematter collectionefficiencyor toagglomeratethe particulatematter tolarger,morereadilyremovableentities.
Awellknownconditioningapproachistheinjectionof S03intotheexhauststreamsfromlow-sulfur coal burning power plants,whichisknownasflue-gasconditioning(FGC).The presenceof theS03reducestheresistivityof theflyashinthesestreamsfor easier capture byESPs.Areviewof recentadvancesinthisareais provided byKrigmontandCoe[148].Someinnovationsincludehot-sideinjection,co-injectionof ammonia(dual-conditioning),anddual-conditioninginfrontof fabricfilterswheretheresultingfilter cakedragcan besignificantlyreduced.A patented processwasdesignedwhere NH3andS03areinjectedataratioof 2:1,inconcentrationsof 1to100 p.p.m.[149].Fabricfilter pressuredropsfor cleaningflyashfromPittsburgh#8
andMonticellocoalsampleswerefoundto betypicallytwoto threetimeslower,andthe particulatematter capturewasalsoimproved.Thisresultwasfollowedup bytestsinAustraliawhichshowedoppositeresults,whereahighlycohesivefilter cakewasreported[150].Thedisparityintheresultswasattributedtodifferencesinthecoalandfabricmaterials.
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Testshave beenconductedwithanumber of differentsulfur andammoniacontainingconditioningcompoundsfor ESPfeeds.Regardingcosteffectiveness,ammoniumsulfate[(NH4)2S041inlowdosageswasfoundto perform bestfor lowsulfur coal
fiyash[151].A relatedtechnologyis knownas sorbentinjection.In thiscase,solidsorbent particulatessuchassilicates,calciumsalts,limes,etc.areinjectedintoagasstreamto adsorbSOxfromthegas.Arecentreview presentssixsuchcommercial pro-cesses[152].Afollowuparticleonhigh-temperaturesorbentinjectionreportsthattheelectricalresistivityof the particulatematter is increasedsubstantiallyandthe
performanceof theelectrostatic precipitator isdegradedaccordingly.Theresistivitymay be brought back to anacceptablelevel bytheuseof fluegashumidificationor conditioningwithS03.Certainmixturesof ashandhighlyreactivesorbentdonot
appear to
respondto
S03conditioning.Various
catalyticadditiveswereviewed
asa potentialmeanstomakehigh-temperaturesorbentinjectiona moreviable pro-cess[153].Sorbentinjection putsincreasedloadson particulatematter collectionequipmentandalsomodifiesthe particulate properties,especiallywithhumidifiedsorbentinjection.Recentresearchhasfocussedondesigningsorbentsystemswhich
possibly benefit,or atleastdonothinder the performanceof the particulatematter removalequipment.TheADVACATE processdeveloped bytheUSEPAusesaspe-cially preparedcalciumsilicatesorbentwhichappearsto bequitecohesiveandentersthesysteminanagglomeratedstatewhichaidstheoverall particulatematter control
bynot
introducingadditionalsubmicronmaterial[154].Babcock &Wilcoxhavede-
velopeda sorbent processdesignedtowork infrontof baghouses[155].ItisknownastheSO,-NO,-RoxBoxTMsystem(SNRB)andisanadvancedair pollutioncontrol processthatsignificantlyreducessulfur oxide(SOx),nitrogenoxide(NOx)and par-ticulateemissionsfromcoal-fired boilers[156].The processusesahigh-temperaturecatalytic baghousefor integratingSOxreduction byinjectinganalkalisorbent(suchashydratedlimeor sodium bicarbonate), NOxremovalthroughammoniainjectionandselectivecatalyticreduction,and particulatecollection.
TheWestinghouseILEC(IntegratedLowEmissionsCleanup)systemrepresentsadifferentapproachtofeedconditioning.Theuseof ceramicfiltersisenvisionedfor
particulatecontrolattemperaturesabove900°Cindirectcoal-firedturbineapplica-tions.Someadhesiveflyash particleswill beemittedthatcouldforma difficult-to-removefilter cake.TheILEC processinjectssorbent particlestoeither removetheadhesive particles beforetheyreachtheceramic barrier filters,or modifytheadhesivenatureof thefilter cakesothatit ismoreeasilyremovable[157].
Froma morefundamental perspective,a recentreviewis availableonhowthe performanceof fabricfiltersandelectrostatic precipitatorsusedtocollectashfromthecombustionof coaldependson bulk propertiesof theash,suchascohesivityor electricalresistivity[158].Anumber of recentfindingshave beencited;thesurface
of flyashwasfoundto beextremelycomplexintermsof chemicalspecies;sorbentmaterialscan beaddedtoenhancesurfacecharge propertiesfor streamstreated byESPs; NH3addedaloneor withS03changesthecohesivityof ash,reducingrappingemissionsfromESPs;smallsizedsorbent particulateshave beenfoundtoactasstericinhibitorstoreducecohesivityof coalashcleaned byfabricfilters;ahumidifiedstream
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infabricfilterswillexhibitalower pressuredropduetothehigher porosityinthedustcake,whichformsmorecompactashagglomerates.AUSDOEexperimental
programisnowunderwaytofollowuponcharacterizingthemechanismsatwork in
fluegasconditioning[159].Acousticagglomerationhas beenrecentlyemployedtoenlargethesizeof submi-cronmaterialsothattheycan beremovedmorereadily byESP.At present,somelaboratorytestinghasshownimprovedresultsonmodelsystems[160,161].Sometheoreticalanalysessuggestthatorthokinetic,hydrodynamicandturbulentmecha-nismscontributetoanincreaseof particle-particlecollisionsfor systemssubjectedtoacousticalvibration[162,163].Anumericalsimulationwasruntomodel bimodal(flyashwithsorbent)acousticagglomeration,withsomecomparisontoexperimentaldata provided.Theneteffectof thecontributingcollisionmechanismswasestimated
bycurve-fitting;no
modellingof theadhesion
process between
particleswas
provid-ed[164].TheUSDOEisaimingtodevelopacousticagglomerationmethodsthatwouldallowtheuseof conventionalcyclonestoachieveveryhigh particulatecollec-tionefficiencyandeliminatetheneedfor barrier filters,whichhave been problematicin viewof durabilityandeconomicsfor proposeddirectcoal-firedturbines[165].A patenthas been procured[166]andinitialtestingisunderway[167].
Yetanother noveltechnologyto beinvestigatedis knownas theelectron beam precharger [168],alsoenvisionedfor coalflyashremoval.Anelectron beamisem- ployedtoionizegasmoleculesina precharger region, producinga bipolar plasmaof ionsandelectronsinacontinuousstateof formationandrecombination.Whensub-
jectedtoastrongelectricfield,the plasmaisseparatedintotwomonopolar fractions.Onlythenegativefractionisusedandisdrawnacrosstheducttochargethedusttoveryhighlevels,whichfacilitatesitsremoval byESP.Theelectron beam precharg-er wasfoundtoimprovethe particulatecollectionefficiencyof aconventionalESP.Testinghasalso beenconductedtocompare pulsecharginginsteadof directcurrentcharging,whichcan bedoneathigher strengthwhereit shouldcreatea morestableenvironmentfor freeelectronsto precharge particles.
3.4.Processmodifications
toreduceemissionsAs partof anoverallstrategytocomplywithenvironmentalstandards,a preferredlonger termsolutionissimplytomodifythe processwhichemitsthe particulatesto lower emissionlevels.Thus,reducedloadis placedonthe particulateremovalequipment.Withoutaugmentationof existingequipment,lower emissionlevelsof
particulatematter can beattained.For example,inthesteelmakingindustry,ithas beendemonstratedthat byreducing
thequantityof limeaddedto thefurnaceearlyintheoxygen blowingcycle,theresultingslag becomesmoreviscousandfoamy,reducing particulateemissions by
upto59%[180].Thechromeelectroplating process producesa toxichexavalentchromiumemission.Changesinfour processconditionswereimplementedwiththeobjectiveof reducingemissionsfromthe process[181].Theseincludedthefreeboardheightof theelectro-
plating bath,eliminationof compressedair for bathagitation,theuseof floating balls
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onthetank surfaceandananti-mist bathadditive.Infour differenttestfacilitiesusingtheir existingcommon particulatematter controlequipment,reductionsinchromiumemissionsof 85-95%wereobserved,allmeetingthequantitativeindustryobjective
of 0.006mg/Ah.Unfortunatelyatthistime,therearenotmanyexamplesof such processesintheliterature, butuseof emissionreductionstrategiesisexpectedtoincreaseinthefuture.
3.5.Sector-specificairborne particulatematter controlconsiderationsAsubjectreceivingconsiderableattentionrecentlyisthetreatmentof emissionsfromincinerationsites.Medical,municipalandindustrialwastes beingincineratedhave
beensubjecttoincreasinglytightregulationsdueto the potentiallytoxiccontentof theemissions.ThewetESPsystem(alsodescribedin Section2.2)has beenfoundto beaneffectivemeansfor reducing particulateandtoxicemissionsfromsewagesludgeincineratorsunder the proposedPart503USEPA(February1989)regulations[169].Part503wouldlimitarsenic, beryllium,cadmium,chromium,lead,mercuryandnickelcontentsof particulateemissionstomaximumconcentrationsof 6.3,42.3,1.8,233.9,125.1,135.5and72.6mg/kg,respectively.TheUSEPAhas
projectedthatmorethan50%of theexistingsewagesludgeincineratorswill beoutof compliancewiththese proposedregulations.Pilottestingwitha post-scrubber feedconsistingof particulatematter whichwas50% below0.6ftm,wasabletoincreasetheoverall particulatematter removalefficiencyfrom98.3to 99.88%.Equipmentoptionsandcostconsiderationsarediscussedfor cleanair actcompliancefor wasteincinerators[170].Astudyof thethenatureandcompositionof incinerator generated
particulatematter asrelatedtofueltypewasdone byHackfortandBorchardt[171].Ashortreviewisavailablewhichdiscusses particulatematter treatmentintheminer-
al processingindustries[172].Four mainsourcesof pollutionareconsidered:miningandsitetreatment,smelting,recyclingandlargescalecombustion processes.Atten-tionisgivento processmodificationswhichreduce particulatematter emissionsor
producegasstreamsmoreamenableto particulatematter removal.A paper devotedtorecentdevelopmentsinironoresinteringdiscussesenvironmentalaspectsinclud-
ing particulatecontrol[173].PertinentESPandscrubbingsystemsarenotedaswellassome processes byBritishSteelandLurgiwhichhave beenupdatedto producelower particulatematter emissionlevels.TheUSDOEconducteda study provid-inganoverviewof particulatematter controltechnologiesfor hotgassteamsfromcoal-firedinstallations[174].Themajor particulatecontroldeviceissuesaddressedincludedtheintegrationof the particulatecontroldevicesintocoalutilizationsystems,on-linecleaningtechniques,chemicalandthermaldegradationof components,fatigueor structuralfailures, blinding,collectionefficiencyasa functionof particlesize,andscale-upof particulatecontrolsystemstocommercialsize.
Particulatecontrolis alsoanissuein the pulpand paper sector.Powers etal.conductedasurveyof applicabletechnologiesfor magnesiumor ammoniumsulfiterecoveryfurnacesin pulpmills[175].WetsystemsarerecommendedinthiscaseassimultaneousS02removalis alsodesired. Normally, pulpmillshavea wastewater treatmentsystem,sotransfer of airbornecontaminantstoanaqueousstreamdoesnot
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poseanadditionalenvironmentalconcern.Successfulsystemstestedona pilotscalewerewetESPsfromFluid-IonicsandBeltran,andMonsanto'sDynawaveScrubber.A similar approachis takenin the particleboardindustry.Fine particulatecleaninghas beensuccessfulwithwetESPsfor
treatingthegasstreamfroma sander dustfireddrumdryer [176].Withtighteningenvironmentalregulations,recoveryof heavymetalemissionsis becomingamorecrucialissue.Of the189HAPsregulatedunder thenewCleanAir Act,11areheavymetalsandmostarecapturedasPM10.Theviabilityof variousexistingandemergingtechnologyfor particulateheavymetalcaptureisdiscussed by
Nudo[177].Ageneraloverviewonthescrubbingof inorganictoxicsisgiven byMcInnesetal.[178].Wetscrubbingor absorptionarethemostcommon particulatematter removalmethodsfor nonmetallicinorganics,whileESPsand baghousesarethe
primaryeffectivemeansof controllingmetals.Aspecialventuriscrubber operatedatalarger pressuredropwhencomparedtostandardventuriscrubbers,wasdesignedtoremoveheavymetalsfromwasteincinerator gasstreamsdowntoUSEPAguidelinelevels[179].Theincreasedoperatingcostsof thissystemmayhinder itswidespreadacceptance.
4.SUMMARYIngeneral,manyof theconventional processunitsusedfor airborne particulatecon-trolareconsideredto
employeffectivemature
technology.Thechoiceof
specificunitsandthewaytheyareinsertedintoanengineeringdesigndependonthesourceof theairborne particulatesandthefinalemissionrequirements.Asurveyof recentrelevantscientificandengineeringliteratureonthissubjecthasrevealedthatmostof theresearchanddevelopmentinthisareaisincremental,andis oftenundertak-entoachievesitespecificobjectivestoreachcompliancewithtighteningemissionsregulations,i.e.air pollutioncontrolunitsaretypicallyinstalledasadd-onsandsomeresearchmay bedonetofinetunetheunittofunction properlyfor eachspecificgasstreaminquestion.Mostreportsof newtechnologiesdescribeenhancedversionsof conventionalunits,whicharesometimesimproved bycombiningcapturemechanismsthatarenormallyexploitedinisolation(i.e.electrificationof fabricfilters).TheUSCleanAir ActAmendmentsof 1990didnotspecificallyupdateregulationsfor all particulateemissions, butthereisgrowingexpectationthatstricter legislationisforthcominginthisarea[182].Asstated previously, particulateemissioncomplianceat presentdoesnot posea serioustechnologicalchallenge.However, particulateemissionsareoftenconcentratedin the0.1-2.0Amdiameter range,sinceexisting
processunitsarecollectivelyleastefficientinremovingsolidsof thissizefromgasstreams.Further,thelistof 189HazardousAir Pollutantstargetedfor controlintheUSCleanAir ActAmendmentscontainsmanyheavymetalsandheavyorganics
whichexistassubmicron particulatematter [183].Healthrelatedstudiesrecommendcleaningof sub-2.5Am particulates,sincematerialinthissizeclassisrespirableandcontributestohumanillness.
TheUSEPAhasanAir andEnergyEngineeringResearchLaboratorywhichalsomonitorstrendsanddevelopmentsinair pollutioncontrol.Theycitedevelopment
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occurringinthe processdesignareawherevariationsof combinationsandsequencesof particulatecontrolunitscan producesomedesired benefit[1].Theconceptof
processdesignandintegrationisincreasinglyimportantfor newinstallationswhere,
for example,novelheat-resistantfilter materialsmay beusedfor particulateremovalatelevatedtemperaturessothattheheatenergymay bemoreefficientlyretained.Coupledwith processdesignaremethodstoreducetheat-sourceemissionof par-
ticulatessothattheir post-processingrequirementsareminimized.For regulationswhichallowemissionsasmass per unitof energygenerated(i.e.fossilfuel based
power stations),upgradingof thefuelsource prior to combustionmay becomein-creasinglynecessary.Scrubbersandagglomeratingsystemswhere particulatesandgaseoustoxicsaresimultaneouslyremovedarealsounder consideration.
Oneareawherenewadvancesare beingmadeinairborne particulatecontroltech-
nologiesis thatof filter materials.Manyof thefabricsusedin baghousesarenowavailablewithhigher thermalandchemicalresistance,longer servicelifeandfiner particlediameter control.Cross-flow, pulsed-jet,ceramictubular andrigidcandle-typefiltersarealsoemployedandshow promisingresults.Manyof thesefilter typesoffer theadvantageof beingreadilyandeasilycleaned.Ceramiccross-flow particulatetrapshave beenshownto performatlevelsmeeting1994EPAstandards.
For the problematicsubmicron particles,muchattentionhas beendevotedtoag-glomerationof these particlestoformlarger conventionallytreatableunits.Modi-ficationsto wetscrubbinghave beenmadewitha pre-treatmentstepwherethegas
streamwassubjectedtoacondensingsteaminjector whichinduced particleagglom-eration[81].Similar pre-treatmentsare beingstudiedfor streamssenttoESPs[184].Other newdirectionsin particulatecontrolrelatetothesourcesgeneratingthe pol-
lution.Municipalwasteincinerationisarelativelyrecent processand posesdifficultyowingto thevariabilityin thefeedstock.Specialcatalyticscrubbersand processdesigncombinationshave beenstudiedfor particulatesfromwasteincineration.
Fromthe presentscientificandtechnical perspective,thefollowingtrendscan beidentifiedasemerginginthedevelopmentof advancedfine particlecontroltechnolo-gies.
(1)Processmodelling,simulationandcontrolfor improved performance.(2)Asaresultof,or closelyrelatedto(1),areopportunitiestointegrateseveraltech-
nologiesthrough processmodelswhichidentifysynergy betweenthetechniques.(3)Sizeenlargementtechniqueswhichmovesub-3fLm particlesintothelarger more
treatablerange.(4)Filtrationmodulesandmaterialsapplicabletohightemperaturesituationsand/or
whicharecleanableandanti-fouling.
AcknowledgementsTheliteraturesurveyusedin preparingthisreviewwascommissioned byDr K.Ra-machadranof EnvironmentCanadafor their TechnologyAdvancementProgramfor AdvancedFineParticleRemoval,under DSScontractno.K2610-4-2050.
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REFERENCES1.EnvironmentCanada.Technologyadvancement programfor advancedfine particleremoval.Envi-
ronmentalProtectionServicereportno.TS-34(1995),82.2.B.B.Crocker,D.A. Novak andW.A.Scholle.Air pollutioncontrolmethods.In:Kirk-Othme
Encyclopediaof ChemicalTechnology,3rdedn,Vol.1.Wiley, NewYork (1984), pp.649-716.3.K.V.Thambimuthu.GasCleaningfor AdvancedCoal-basedPower Generation.IEACoalResearch,London(1993).
4.W.Strauss.IndustrialGasCleaning,2ndedn.PergamonPress,Oxford(1975).5.A.Tamir.Impinging-StreamReactors.FundamentalsandApplications.Elsevier,Amsterdam(1994).6.A.J.BuonicoreandW.T.Davis(Eds).Air PollutionEngineeringManual.Van NostrandReinhold, NewYork (1992).
7.P. N.Cheremisinoff (Ed.).Air PollutionDesignandControl for Industry.MarcelDekker, NewYork (1993).
8.J.E.Brockmann,C.L.J.AdkinsandF.Gelbard.Alternate particleremovaltechnologiesfor theAirborne
ActivityConfinement
SystemattheSavannahRiver Site.USDOE
reportWSRC-RP-9
0928(1991),), 108.9.K.Schifftner.FluxForceCondensationScrubbersfor utilizationonmunicipalsolidwasteinciner-ators.In:JointASME/IEEEPower GenerationConf.Dallas,TX(1989)(ASME paper 89-JPGC/EC-5).
10.P.A.Lawless,A.S.Viner,D.S.Ensor andL.E.Sparks.Computationsonthe performanceof particlefiltersandelectronicair cleaners.In:5thInt.Conf.Indoor Air QualityandClimate,Vol.3.Toronto,Canada(1990), pp.187-192.
11.J.vanHeerdenandP.Sullivan.Theapplicationof CFDfor evaluationof dustsuppressionandauxiliaryventilatingsystemsusedwithcontinuousminers.In:Proc.6thUSMineVentilationSymp.SaltLakeCity,UT(1993), pp.293-297.
12.A.Samanta,
R.Bhaskar andR.Gong.Studiesontheuseof scrubbersincontinuousminer faces.In:Proc.6thUSMineVentilationSymp.SaltLakeCity,UT(1993), pp.51-56.13.P.Schmidt.Unconventionalcycloneseparators.Int.Chem.Eng.33,8-17(1993).
14.P.SchmidtandT.Richter.Duststrandsincycloneseparatorsatlowdustconcentration.Part.Sci.Technol.11,107-113(1993).
15.J.Plucinski,L.GradonandJ. Nowicki.Collectionof aerosol particlesinacyclonewithanexternalelectricfield.J.AerosolSci.20,695-700(1989).
16.C.E.Romero,D.W.ShawandJ.S.Ontko.Particlecollectionefficiencyof acycloniccombustor.In:AIAA/ASME NationalFluidDynamicsCongr.LosAngeles,CA(1992)(reportDOE/METCC-92/7020).
17.J.Barrett.Spinningtubecleansupemissions.Eureka13,26-27(1993).
18.C.WadenpohlandF.Löffler.Anelectro-mechanicaltwo-stagesystemfor theseparationof dieselsoot particles.In:Air PollutionControl:Papersfromthe9thWorldCleanAir Congr.Montreal,Canada(1992)(paper IU-18F-02).19. NationalTechnicalInformationService,UnitedStates.Electrostatic precipitators(Latestcitations
fromthe NTISBibliographicDatabase),Feb.1994,250citations,documentPB94-866779/X20.EPRI-Int.Soc.Electrostatic precipitation.10thParticulateControlSymp.and5thInt.Conf.on
ElectrostaticPrecipitation.Washington,DC(1993).21.G.R.OffenandR.F.Altman.Issuesandtrendsinelectrostatic precipitationtechnologyfor US
utilities.J.Air WasteManage.Ass.41, 222-227(1991).22.H.J.DelGatto.Don'tletESP becomeAchilles'heelof compliancestrategy.Power 138,81-84
(1994).
23.R.P.Gaikwad,D.G.Sloat,R.AltmanandR.L.Chang.Economicevaluationof electrostati precipitator retrofitoptions.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostatiPrecipitation,Vol.1.Washington,DC(1993).24.R.L.Andrews,C.A.AltinandR.Salib.ESPsinthe21 stcentury:extinctionor evolution.In:10th
ParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.1.Washington,DC(1993).
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 31/37
209
25.R.A.MastropietroandR.LeBeau.Rebuildandenlargementof existingweighted-wireESPsasaresultof coalswitching.In:5thInt.Conf.andExhibitionfor thePower GeneratingIndustries-POWER-GEN'92.Orlando,FL(1992), pp.48-65.
26.T.Tanaka,H.FujishimaandY.Tsuchiya.Developmentof advanceddustcollectingsystemfor coal-
fired power plant.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).27.H.Yabuta.Recentdustcollectiontechnologyfor utility-use boilers.HitachiRev.39,355-362(1990).28.G.Dinelli,V.BoganiandM.Rea.Enhanced precipitationefficiencyof electrostatic precipitators by
meansof impulseenergization.IEEETrans.Ind.Appl.27,323-330(1991).29. N.TachibanaandY.Matsumoto.Intermittentenergizationonelectrostatic precipitators.J.Electro-
statics25, 55-73(1990).30.T.Watanabe,F.Tochikubo,Y.Koizumi,J.Tsuchida,J.HautanenandE.I.Kauppinen.Submicron
particleagglomeration byanelectrostaticagglomeration.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.1.Washington,DC(1993).
31.H.R.Falaki.Experimentalstudy
of flowdiversionduring
therapping
of collector plates
insideanelectrostatic precipitator.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).
32.L.LindandE.M.Bojsen.Experiencewith baffle-freecollecting platesinanelectrostatic precip-itator.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).
33.V.S.Lee.USEPA-developedair-pollutioncontroltechnology.In:1st N.AmericanConf.onEmergingCleanAir TechnologiesandBusinessOpportunities.Toronto,Canada(1994).
34.V.ReyesandP.Lausen.Utilizationof expertcomputer systemsfor controlandoperationof elec-trostatic precipitators.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecip-itation,Vol.2.Washington,DC(1993).
35.Anon.UseadvancedcontrolstomaximizeESPefficiency.Power 135,56-57(1991).36.C.Eyraud.Gascleaning bywetelectrostatic precipitation:new prospects.Filtr.Sep.30,637-639(1993).
37.H.FujishimaandY.Tsuchiya.Applicationof wettypeelectrostatic precipitator for utilities'coal-fired boiler.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation.Washington,DC(1993).
38.A.C.Sheth,J.K.Holt,J.R.DouglasandB.R.Thompson.Roleof thewetelectrostatic precipitator inthecoal-firedmagnetohydrodynamicssystem.In:Symp.onEngineeringAspectsof Magnetohy-drodynamics(SEAM30Proc.).Baltimore,MD(1992), pp.9.1-9.11.
39.M.Valenti.Emissioncontrol:retrofitting process plantsfor the1990s.Mech.Eng.114,68-74(1992).
40.E.H.Weaver.Innovativedesignfeaturesfor electrostatic precipitatorsinstalledon biomassfired boilers.In:Proc.1994IndustrialPower Conf.SanFrancisco,CA(1994), pp.73-85.41.D.B.Kittelson,J.ReinertsenandJ.Michalski.Further studiesof electrostaticcollectionandag-
glomerationof diesel particles.In:GlobalDevelopmentsinDieselParticulateControl.Warrendale,PA,Societyof AutomotiveEngineers,Publ.P-240(SAEtech. paper 910329)(1991), pp.145-163.
42.R.Ettema.Electrostatic precipitator performanceimprovementthroughnumericalsimulation.WorldCement25,63-66(1994).
43.W.-J.LiangandT.H.Lin.Thecharacteristicsof ionicwindanditseffectonelectrostatic precipitators.J.AerosolSci.20,330-344(1994).
44.M.Abdel-Salam.Influenceof humidityonchargedensityandelectricfieldinelectrostatic precipi-
tators.J. Phys.D.Appl.Phys.25,1318-1322(1992).45.V.H.Belba,W.T.GrubbandR.L.Chang.The potentialof pulse-jet baghousesfor utility boilers.Part1:Aworldwidesurveyof users.J.Air WasteManage.Ass.42,209-213(1992).46.C.J.Bustard,J.M.CushingandR.L.Chang.The potentialof pulse-jet baghousesfor utility boilers.
Part2:Performanceof pulse-jetfabricfilter pilot plants.J.Air WasteManage.Ass.42,1240-1249(1992).
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 32/37
210
47.D.G.Sloat,R.P.GaikwadandR.L.Chang.The potentialof pulse-jet baghousesfor utility boilers.Part3:Comparativeeconomicsof pulse-jet baghouse, precipitatorsandreverse-gas baghouses.Air Waste43,120-128(1993).
48.B.Svensson.Advancedfabricfiltersfor effectiveemissioncontrolinthesteelmakingindustry.ABB
Rev.10, 23-26(1990).49.Anon.Advancedfiltrationtechnologytosatisfytomorrow'slegislation.Filtr Sep.30,37-38(1993).50.W.Brame.Fabricfilter apparatus,AustralianPat.AU-B-35992/89(1989).51.T.G.Ebner,C.J.Bustard,F.J.SaganandR.L.Chang.Designanddevelopmentof anovelfilter
cagefor improvedcleaningandextended baglife.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.1.Washington,DC(1993).
52.T.Gennrich.Filter bagshelpmeet particulatecontrolstandards.Power Eng.97,37-39(1993).53.G.A.Kudlac,G.A.Farthing,T.SzymanskiandR.Corbett.SNRBcatalytic baghouselaboratory
pilottesting.Environ.Prog.11,33-38(1992).54.W.T.McKenna.Filter mediaselectionfor fabricfilters.Industrial boilers,CFBs,andincinerators
In:Proc.1990 Ind.Power Conf.,PWR Vol.9.StLouis,MO(1990), pp.9-13.
55.G.A.Brinckman.MicroporousGore-Tex®membranefilter mediacanhelpcontrolsubmicron par-ticulatematter,heavymetal,anddioxan/furanemissions.In:Air andWasteManagementAss.85thAnn.MeetingandExhibition.KansasCity,MO(1992)(paper 92-111.05).
56.F. Noël,M.Dufour andG.Gosselin.Developmentof adustcollector for bark boiler exhaustgases.In:1st N.AmericanConf.onEmergingCleanAir TechnologiesandBusinessOpportunities.Toronto,Canada(1994).
57.G.Gosselin.Processfor removingdustfromhightemperaturegasstreams.USPat.5112368(1992).58.R.Barnes.A parametricstudyof theeffectsof textile processingvariablesonthefiltrationefficiency
of a wovenglassfabric.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostatiPrecipitation,Vol.1.Washington,DC(1993).
59.L.Bergmann.Conductivefabricsindustcollectors.Staub.Reinhaltungder Luft53, 307-309(1993).60.T.GrafeandG.Kelley.Baghouseandcartridgedustcollectors:acomparison.Am.Cer.Soc.Bull.72,69-73(1993).61.G.F.Weber,S.R. NessandD.L.Laudal.Simultaneous NOxand particulatecontrolusinga
catalyst-coatedfabricfilter.In:Int.Power GenerationConf.SanDiego,CA(1991)(ASME paper 91-JPGC-FACT-2).
62.G.F.Weber,S.R. NessandG.L.Schelkoph.Catalyticfabricfiltrationfor simultaneous NOxand par-ticulatecontrol.Quarterlytechnical progressreport,Oct.1-Dec.31, 1993.ReportDOE/PC/9036T13(1994).
63.A.S.Viner,G.P.Greiner andL.S.Hovis.Advancedelectrostaticstimulationof fabricfiltration: performanceandeconomics.JAPCA38,1573-1582(1988).
64.S.RaoandD.V.S.Murthy.
Electrostaticallyenhancedfabricfiltration.CEWChem.Eng.World24, 21-24(1989).65.Y.Yamamoto.Filter for particulatematerialsingaseousfluids.USPat.5368635(1994).
66. NationalTechnicalInformationService,UnitedStates.Gasscrubbers(Latestcitationsfromthe NTISDatabase),July1993,111citations,documentPB93-881811/XAD.
67.P.J.Loftus,D.B.Stickler andR.C.Diehl.Confinedvortexscrubber for fine particulateremovalfromthefluegases.Environ.Prog.11,27-32(1992).
68.K.A.Jonsson.Gascleaningmethodsandapparatus.USPat.5076818(1991).69.D.P.Burfordand1.G.Pearl.InitialresultsfromtheCT-121innovativecleancoaltechnology
demonstration projectatGeorgia power's plantYates.In:Proc.JointASME/IEEEPower GenerationConf.KansasCity,KS(1993)(ASME paper 93-JPGC-EC-12).
70.J.J.Schwab.Venturiscrubber and process.USPat.5279646(1994).71.K.D. NguyenandD.R.Spink.Scrubber productsfor acidrainandair toxicscontrol.In:1st N.AmericanConf.andExhibition:EmergingCleanAir TechnologiesandBusinessOpportunitieToronto,Canada(1994).
72.C-C.Chen,H-K.ShuandY-K.Yang. Nucleation-assisted processfor theremovalof fineaerosol particles.Ind.Eng.Chem.Res.32,1509-1519(1993).
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 33/37
211
73.S.V.Sheppard.Fine particleremovalfor hazwasteincineratorswiththeionizingwetscrubber.In:86thAnn.MeetingAir andWasteManagementAssociation.Denver,CO(1993)(paper 93-TP51.01).
74.T.F.Burger,D.M.Collins,S.M.CollinsandM.R.Burger.Circulatingair scrubber.CanadianPat.1316122(1993).
75.L.R.Waterland,D.J.Fournier,Jr.,J.W.LeeandG.J.Carroll.Tracemetalfateinarotarykilnincinerator withanionizingwetscrubber.WasteManage.11,103-109(1991).76.S.Sumiyoshitani.Effectsof anappliedelectricfieldoncollectionefficiency byachargeddropletfor dust particlesinchargeddropledscrubbers.AerosolSci.Tech.20, 71-82(1994).77.H.Polat,Q.Hu,M.PolatandS.Chander.Theeffectof dropletand particlechargeondustsup-
pression bywettingagents.In:Proc.6thUSMineVentilationSymp.SaltLakeCity,UT(1993), pp.535-541.
78.E.B.Hanf andW.Ellison.FGDmisteliminatorsfor 0.002LB/MMBTUsolid particulateemission.In:Proc.JointASME/IEEEPower GenerationConf.KansasCity,KS(1993)(ASME paper 93-JPGC-EC-9).
79.Anon.Two-stagescrubber
systemremoves
HCl,Cl2.Chem.Eng.Prog.10,23(1994).80.A.1.Lainer,T.D.Israfilov,1.T.ElperinandV.L.Meltser.Studyof counterflowtrappingof alunitedust.Sov.J. Non-FerrousMetals48,43-45(1975).81.J.Sun,B.Y.H.Liu,P.H.McMurryandS.Greenwood.Methodtoincreasecontrolefficienciesof
wetscrubbersfor submicron particlesand particulatemetals.J.Air WasteManage.Ass.44,184-185(1994).
82.K.W.Wilson,J.C.HaasandM.B.Eshelman.Applicationsof movinggranular-bedfilterstoadvancedsystems.In:Coal-firedPower Systems'93:AdvancesinIGCCandPFBCReviewMeeting.Morgantown,WV(1993)(reportDOE/MC/27423-93/C0215).
83.K.W.Wilson,J.C.HaasandM.B.Eshelman.Granular-bedandceramiccandlefiltersincommercial plants:acomparison.ReportDOE/MC/27423-3513(1993).
84.W.Yang,R. Newby,T.LippertandD.Keairns.MGBFconceptlooksgoodfor hotgascleanup.ModemPower Sys.12, 21-24(1992).85.C.A.P.Zevenhoven,B.ScarlettandJ.Andries.Thefiltrationof PFBCcombustiongasinagranular
bedfilter.Filtr.Sep.29,239-244(1992).86.C.A.P.Zevenhoven,K.R.G.HeinandB.Scarlett.Movinggranular bedfiltrationwithelectrostatic
enhancementfor high-temperaturegasclean-up.Filtr.Sep.30,550-553(1993).87.J.S.Mei,P.C.YueandJ.S.Harlow.Fluidized-bedfiltrationfor particulateclean-up.In:Proc.1993
Int.Conf.onFluidizedBedCombustion.SanDiego,CA(1993), pp.1351-1358.88.T.C.Ho,L.Tan,C.ChenandJ.R.Hopper.Metalemissionscontrolthroughheterogeneousdepo-
sitionduringfluidized bedincineration.J.Hazard.Mater.24,292-293(1990).89.B. Neukirchen.Reductionof
heavymetalanddioxanemission
bymeansof anactivatedcarbonfilter
onthehazardouswasteincinerationfacilityatRZR Herten.In:Air PollutionControl:Papersfromthe9thWorldCleanAir Congr.Montreal,Canada(1992)(paper IU-18E-04).90.W.PeukertandF.Löffler.Influenceof temperatureon particleseparationingranular bedfilters.
Powder Technol.68,263-270(1991).91.Y.Otani,C.KanaokaandH.Emi.Experimentalstudyof aerosolfiltration bythegranular bedover
awiderangeof Reynoldsnumbers.AerosolSci.Technol.10, 463-474(1989).92.SorbentTechnologiesCorp.Supported-sorbentinjection.In:1st N.AmericanConf.andExhibition:
EmergingCleanAir TechnologiesandBusinessOpportunities.Toronto,Canada(1994).93.J.G.Toher,P.FeldmanandK.S.Kumar.Circulatingdryscrubbers-presentandfuturecapabil-ities.In:1st N.AmericanConf.andExhibition:EmergingCleanAir TechnologiesandBusiness
Opportunities.Toronto,Canada(1994).94.H.R.Paur,W.Schikarski,W.Baumann,C.H.Leichsenring,W.Linder andH.Mätzing.Stateof theartinelectron beamdryscrubbingof fluegas.In:Air PollutionControl:Papersfromthe9thWorldCleanAir Congr.Montreal,Canada(1992)(paper IU-18A-03).
95.P.M.Eggerstedt,J.F.ZieversandE.C.Zievers.Choosetherightceramicfor filteringhotgases.Chem.Eng.Prog.89,62-68(1993).
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 34/37
212
96.L.R.White,T.L.Tompkins,K.C.HsiehandD.D.Johnson.Ceramicfiltersfor hotgascleanup.J.Eng.GasTurb.Power 115,665-669(1993).
97.C.Butcher.Hotnewsinceramicfilters.Chem.Eng.(London)505,27-29(1991).98.T.W.Smith. Newdevelopmentsinhigh-efficiency particulateair filtration.Am.Cer.Soc.Bull.72,
79-84(1993).99.J.Seville.Handlinghotgas.ProcessEng.74,51-54(1993).100.G.OndreyandS.Moore.Gascleaningcomesoutof the bag.Chem.Eng.101, 28-31(1994).101.W.Cheung,J.P.K.Seville,R.Clift,C.J.Bower andA. N.Twigg.Filtrationandcleaningcharacter-
isticsof ceramicmedia.In:4thInt.FluidizedCombustionConf.London(1988), pp.II/9/ 1-II/9/ 1102.J.Stringer andA.J.Leitch.Ceramiccandlefilter performanceattheGrimethorpe(UK) pressurized
fluidized bedcombustor.In:Int.GasTurbineandAeroengineCongr.andExposition.Orlando,FL(1991)(ASME paper 91-GT-381).
103.J.Stringer andA.J.Leitch.Ceramiccandlefilter performanceattheGrimethorpe(UK) pressurizedfluidized bedcombustor.J.Eng.GasTurbinesPower Trans.ASME114,371-379(1992).
104.M.Durst,M.Müller,M.R.SchnellandA.R.Wagner.Performanceof rigidceramicfilter elements
inan8,000hour durabilitytestathightemperatures.In:Proc.1991Int.Conf.onFluidizedBedCombustion,Vol.3.Montreal,Canada(1991), pp.1081-1086.105.S.Laux,B.Giernoth,H.Bulak andU.Renz.Hotgasfiltrationwithceramicfilter elements.In:
Proc.1993 Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.1241-1251.106.R.Clark,P.Holbrow,J.E.Oakley,K.BurnardandJ.Stringer.Somerecentexperienceswiththe
EPRIhotgasrigidceramicfilter atGrimethorpePFBCestablishment.In:Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.1251-1258.
107.C.E.Selmer andW.T.Bakker.Evaluationof siliconcarbidecandlefilters.In:Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.1259-1264.
108.T.Eriksson,J.Isaksson,P.StÅberg,E.KurkelaandV.Helanti.Durabilityof ceramicfiltersinhot
gasfiltration.BioresourceTechnol.46,103-112(1993).
109.K.R.Valentino, N.R.Brown,J.J.Brown,Jr.andW.T.Bakker.Durabilitytestingof ceramiccandlefiltersinPFBSenvironments.In:Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.1375-1383.
110.H.Leibold,F.DirksandV.Rüdinger.ParticulateemissionsfromaLLWincinerator andoff-gascleaningwithanewtypeof ceramiccandlefilter.WasteManage.9, 87-94(1989).
11 J. Jalovaara,I.HippinenandA.Johkola.ParticleremovalinPFBCusingafibrousceramiccandlefilter.In:Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993),
pp.713-718.112.R.A.BrownandA.J.Leitch.Filtrationof PFBCdustsusingarigidceramictubetypefilter.In:
Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.1229-1239.
113.K.HigashiandH.Maeno.Thelateststatusof the
developmentof theadvancedceramictubefilter.
ReportsRes.AsahiGlassCo.,Ltd.42,81-95(1992).114.J.P.K.Seville,R.Legros,C.M.H.Brereton,C.J.LimandJ.R.Grace.Performanceof rigidceramicfiltersfor CFBCgascleaning.In:Proc.1991Int.Conf.onFluidizedBedCombustioVol.1.Montreal,Canada(1991), pp.279-286.
115.M.J.MuddandJ.D.Hoffman.OperatingdatafromtheTIDDhotgascleanup program.In:Proc.1993 Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.719-727.
116.T.E.Lippert,G.J.Bruck,R.A. NewbyandE.E.Smeltzer.Specificfilter designsfor PFBC.In:Coal-firedPower Systems'93:AdvancedinIGCCandPFBCReviewMeeting.Morgantown,WV(1993)(reportDOE/MC/21023-93/C0212).
117.J.F.Zievers,P.Eggerstedt,E.C.ZieversandD. Nicolai.Whataffectsthecostof hotgasfilter
stations?J.Eng.GasTurbinesPower,Trans.ASME115, 652-657(1993).118.C.M.Urban,L.C.LandmanandR.D.Wagner.Dieselcar particulatecontrolmethods.In:DieselParticulateEmissionsControl.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 830084)(1983), pp.87-96.
119.P.R.Miller,J.Scholl,S.Bagley,D.LeddyandJ.H.Johnson.Theeffectsof a porousceramic particulatetraponthe physical,chemicaland biologicalcharacter of diesel particulateemissions.
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 35/37
213
In:DieselParticulateEmissionsControl.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 830457)(1983), pp.159-185.
120.J.J.Tutko,S.S.Lestz,J.W.Brockmeyer andJ.E.Dore.Feasibilityof ceramicfoamasadiesel particulatetrap.In:DieselParticulateTraps.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 840073)(1984), pp.15-24.121.C.Bertoli,F.E.Corcione, N.DelGiacomo,G.PoliceandM.Migliaccio.Performanceevaluationof particulatetrapsfor passenger car dieselengines.In:AdvancesinEngineEmissionControlTechnology.Presentedatthe12thAnn.Energy-SourcesTechnologyConf.andExhibition.Houston,TX(1989), pp.27-35.
122.K.Takesa,T.UchiyamaandS.Enamito.Developmentof particulatetrapsystemwithcrossflowceramicfilter andreversecleaningregeneration.SAETrans.100, 428-439(1991)(SAEtech. paper 910326).
123.K.Takesa,T.UchiyamaandS.Enamito.Developmentof Asahi particulatetrapsystem.ReportsRes.AsahiGlassCo.,Ltd41,197-214(1991).
124.J.Kitagawa,
T.HijikataandS.Satoru.Electricheatingregenerationof largewall-flowtypeDPF.In:GlobalDevelopmentsinDieselParticulateControl.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 910136)(1991), pp.63-71.
125.A.Balzotti,G.M.Cornetti,F.Pidello,M.SigneandV.Scorsone.Italiancity buseswith particulatestraps.In:AdvancesinDieselParticulateControl.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 900114)(1990), pp.79-86.
126.S.T.Gulati,D.W.Lambert,M.B.HoffmanandA.Tuteja.Thermaldurabilityof aceramicwall-flowdieselfilter for lightdutyvehicles.In:DieselParticulateControl,Trap,andFiltrationSystems.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 920143)(1992), pp.69-79.
127.M.G.Grenier andS.G.Hardcastle.SafetyandhealthintheCanadianmineenvironment.Anoverviewof ventilation,dust,radiationanddieselemissionresearch.CIMBull.83,41-46(1990).
128.F.B.Walton,P.J.HaywardandD.J.Wren.Controlledenergydepositionindiesel particulatefiltersduringregeneration bymeansof microwaveirradiation.In:AdvancesinDieselParticulateControl.Warrendale,PA,Societyof AutomotiveEngineers(SAEtech. paper 900327)(1990), pp.131-140.129.R.F.AbramsandR.L.Goldsmith.Fieldtestingof ceramicmembranegasfilters.In:10thParticulate
ControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).130.C.J.Bustard,S.M.Sjostrom,R.H.SlyeandJ.Foote.Applicationof novelfiltrationtechnolo-
giestotheMHD process.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).
131.R.L.GoldsmithandB.A.Bishop.Catalyticfiltrationdeviceandmethod.USPat.5221484(1993).132.K.Benedek andM.Flytzani-Stephanopoulos.Cross-flow,filter-sorbentcatalystfor particulate,SO2
and NOxcontrol.Seventhquarterlytechnical progressreport.ReportDOE/PC/89805-T8,1992.
133.R.A. Newby,T.E.Lippert,E.E.Smeltzer,A.RobertsonandD.Bonk.Crossflowfilter performancewithsecond-generationPFBCcarbonizer fuelgas.In:Proc.1993Int.Conf.onFluidizedBedCombustion,Vol.2.SanDiego,CA(1993), pp.703-712.134.M.ParishandA.B.Jeffrey.Ceramicfilter elementswithtailoredmacro-andmicrostructures.Filtr.
Sep.32,31-35(1995).135.R.Chang.CompactHybridParticulateCollector (COHPAC).USPat.5158580(1992).136.L.Lamarre.COHPingwith particulates.EPRIJ.18,18-23(1993).137.A.K.Hindocha,B.BrownandR.Chang.Commercialdemonstrationof COHPAC.In:10thPar-
ticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.1.Washington,DC(1993).
138.K.Steinbacher,H.SchmidtandW.Leussler.Processandapparatusfor purifyingdustand pollutant-
containingexhaustgases.AustralianPat.AU643794(1993).139.K.Steinbacher,H.SchmidtandW.Leussler.VerfahrenandVorrichtungzunReinigungstaub-undschadstoffhaltiger Abgase.EuropeanPat.EP461695(1991).
140.H.Schen.Pollutionemissioncontrolsystem.USPat.5171446(1992).141.J.Dixkens,H.FissanandT.Dose. New particlesamplingtechniquefor directanalysisusing
total-reflectionX-rayfluorescencespectrometry.Spectrochim.Acta48B,231-238(1993).
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 36/37
214
142.R.M.Burton.Methodandapparatusfor samplingair contaminants.PCTInt.Pat.WO9306910(1993).
143.Anon.Highvolume particlesamplingandanalysis.AtmosphericMonitoring&Abatement News,July,7(1994).
144.D.E.Pike.Apparatusfor thequantificationof dustcollectibility.USPat.5119684(1992).145.Anon.Choosingthecorrect particulatemonitor for your facility.BHAGroupInc.,companyliter-ature,June14(1994).
146.S.Rowsell.Spark detectionhelpto preventfiresindustcollectionsystems.Cdn.Firefighter,July,19 (1995).
147.K.Morris.Expertsystemcontrolof fabricfilters.Filtr.Sep.28, 275-280(1991).148.H.V.KrigmontandE.L.Coe,Jr.Flue-gasconditioning:keyadvancesinrecentyears.Power 136,
30-36(1992).149.D.L.LaudalandS.J.Miller.Controlling particulateemissionsfromcoalcombustion plantstacks-
ammoniaandsulphur trioxidegasesareinjectedupstreamof baghouse.USPat.5034030(1991).150.W.
Humphries,R.Beck
andA.Lowe.Effectof ammoniainjectiononfabricfilter pressuredrop.J.Air WasteManage.Ass.41,1523-1527(1991).151.L.A.Rikhter,S.L.Chernov,A.A.AverinandS.V.Cherepov.Improvingtheefficiencyof removalof high-resistanceashinelectrostatic precipitators bychemicalconditioningof fluegases.ThermalEng.38, 137-140(1991).
152.R.S.Dahlin,T.R.Snyder andP.V.Bush.Effectsof sorbentinjectionon particulate properties.PartI.Low-temperaturesorbentinjection.J.Air WasteManage.Ass.42,1592-1602(1992).153.R.S.Dahlin,T.R.Snyder andP.V.Bush.Effectsof sorbentinjectionon particulate properties.PartII.High-temperaturesorbentinjection.J.Air WasteManage.Ass.43,91-96(1993).154.C.B.Sedman,R.E.Valentineand N.Plaks.Evaluationof pilotESP performancewithelevated
loadingsfromsorbentinjection processes.In:9thSymp.onParticulateControl.Williamsburg,VA
(1991)(reportEPA/600/D-91/244).155.J.B.Doyle,E.A.PirshandW.Downs.Integratedinjectionand bagfilter housesystemfor SOx-NOx particulatecontrolwithreagent/catalystregeneration.CanadianPat.1273474(1990).
156.G.A.Kudlac,G.A.Farthing,T.SzymanskiandR.Corbett.SNRBcatalytic baghouselaboratory pilottesting.Environ.Prog.11, 33-38(1992).
157.R.A. Newby,M.A.Alvin,D.M.Bachovchin,W.C.Yang,E.E.Smeltzer andT.E.Lippert.IntegratedLowEmissionsCleanupsystemfor directcoalfueledturbines(moving bed,fluid bedcontactor/ceramicfilter).Twenty-fifthquarterlyreport,Oct.-Dec.1993.ReportDOE/MC/2423705(1993).
158.P.V.BushandT.R.Snyder.Implicationsof particulate propertiesonelectrostatic precipitator andfabricfilter performance.Powder Technol.72, 207-213(1992).
159.T.R.Snyder.Fundamentalmechanismsinfluegasconditioning.Quarterlyreport,Oct.-Dec.1993.ReportDOE/PC/90365-T13(1994).160.J.Magill,P.Caperan,J.Somers,K.Richter,S.Fourcaudot,P.Barraux,P.Lajarge,J.A.Gallego-
Juarez,E.Riera-FrancoDeSarabia,G.Rodriguez-Corraland N.Seyfert.Characteristicsof anelectro-acoustic precipitator (EAP).J.AerosolSci.23,S803-S806(1992).
161.A.Renoux.Actiondesondesacoustiquessur lesaerosols.In:Air PollutionControl:Papersfromthe9thWorldCleanAir Congr.Montreal,Canada(1992)(paper IU-18F-05).162.L.Song,G.H.KoopmanandT.L.Hoffmann.Animprovedtheoreticalmodelof acousticagglom-eration.J.Vib.Acoustics,Trans.ASME116,208-214(1994).163.M.A.Al-Nimr andV.S.Arpaci.Acoustical propertiesof interactingandagglomerated particles.
J.SoundWb,165,19-30(1993).164.T.L.Hoffmann,W.Chen,G.H.Koopman,A.W.ScaroniandL.Song.Experimentalandnumericalanalysisof bimodalacousticagglomeration.J.Vib.Acoustics,Trans.ASME115,232-240(1993).165.M. N.Mansour,R.R.Chandran,J. N.Duqum,A.W.Scaroni,G.H.KoopmanandJ.L.Loth.
Particlecollectionenhancement byacoustics.In:Coal-firedPower Systems'93:AdvancesinIGCCandPFBCReviewMeeting.Morgantown,WV(1993)(reportDOE/MC/26288-93/C0
7/27/2019 Developmentsin the control of fine particulate.pdf
http://slidepdf.com/reader/full/developmentsin-the-control-of-fine-particulatepdf 37/37
215
166.M. N.Mansour.Pulsecombustedacousticagglomerationapparatusand process.USPat.5197399(1993).
167.USDOE.SonicEnhancedAshAgglomerationandSulfur Capture.Quarterlytechnical progressreport,Sept.1993-Jan.1994.ReportDOE/MC/26288-3688(1993).
168.W.C.FinneyandW. N.Shelton.Pulsedelectron beam precharger.Finalreport,Sept.1989-May1992(progressreport).ReportDOE/PC/89768-T14(1992).169.L.H.Hentz,F.B.JohnsonandA.Baturay.Air emissionstudiesof sewage-sludgeincineratorsat
thewestern branchwaste-water treatment-plant.Water Environ.Res.64,111-119(1992).170.V.J.PettiandP.Maurin.'Cleanair actcompliance'trash-to-energyfacilities-retrofittingfor acid
gascontrol.In:Proc.JointASME/IEEEPower GenerationConf.KansasCity,KS(1993)(ASME paper 93-JPGC-FACT-5).
171.H.HackfortandJ.Borchardt.Influencingandcontrollingultrafine particulateemissionsfromaCFB-wasteincinerator.J.AerosolSci.23,S729-S732(1992).
172.A.Arrowsmithand N.Ashton.Air pollutioncontrolfromthemineral processingindustries.Min-eralsEng.4,1071-1080(1991).
173.P.R.Dawson.Recentdevelopmentsiniron-oresintering.Part4:Thesintering process.Ironmaking&Steelmaking20,150-159(1993).174.USDOE.Hotgascleanuptestfacilityfor gasificationand pressurizedcombustion.Quarterly
technical progressreport,Oct.-Dec.1992.ReportDOE/MC/25140-3555(1992).175.W.E.Powers,M.W.Short,J.A.EvensenandB.A.Dennison.Retrofitoptionsfor controlling
particulate-emissionsfromamagnesiumsulfiterecoveryfurnace.TappiJ.75,113-120(1992).176.D.Adair,J.L.StaffordandG.A.Raemhild.Innovativedryer andemissioncontrolsystemsat
a particleboardinstallation.In:Proc.WashingtonStateUniversityInt.Particle-board/ComposMaterialsSeriesSymp.Pullman,WA(1990), pp.209-225.
177.L. Nudo.Capturingheavymetals.Pollut.Eng.25,80-82(1993).178.R.McInnes,K.JamesonandD.Austin.Scrubbingtoxicinorganics: particulatesarecontrolled
with baghousesor electrostatic precipitators,whilenonmetallicsarescrubbed.Chem.Eng.97(9),116-121(1990).179.R.J.Cowley,B.P.Gallagher andB.M.,Jr. Nee.Developmentandexecutionof ametals pretest
programfor ahazardouswasteincinerator.Hazard.WasteHazard.Mater.11(1), 31-51(1994).180.E.Cocchiarella,M.S.GreenfieldandS.Chubbs.Theeffectof foamyslagon basicoxygen
steelmaking processemissions.CIMBull.86(974), 56-61(1993).181.C.A.PopejoyandF.R.Weintraub.Asystemsapproachtocontrollingchromeelectroplating
emissions.In:Air PollutionControl:Papersfromthe9thWorldCleanAir Congr.Montreal,Canada(1992)(paper IU-18E-10).
182.R.W.McIlvaine.Forecastandmarketsfor particulatecontrolsystems.In:10thParticulateControl
Symp.and5thInt.
Conf.onElectrostatic
Precipitation,Vol.1.
Washington,DC
(1993).183.P.L.FeldmanandK.S.Kumar.Thechallengeof high-efficiencycontrolof fine particles.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.2.Washington,DC(1993).
184.M.D.Durham,D.B.Holstein,R.G.Rhudy,R.F.Altman,T.A.Burnett,L.LepovitzandG.Blythe.Performanceof ESPswithsmallSCAsinspraydryer retrofitapplications.In:10thParticulateControlSymp.and5thInt.Conf.onElectrostaticPrecipitation,Vol.1.Washington,DC(1993).