Fundamental Research Of Charge Effects And Regulation In Electrostatic Precipitation

Particulate(?)matter(?)emitted(?)by(?)combustion,especially(?)fine(?)particulate(?)matter,is(?)one(?)of(?)the(?)important(?)causes(?)of(?)haze.Emissions(?)of(?)particulate(?)matter(?)from(?)industrial(?)combustion(?)sources(?)account(?)for(?)80%(?)of(?)the(?)total(?)national(?)emissions.Under(?)the(?)demand(?)for(?)the(?)continuous(?)improvement(?)of(?)air(?)quality(?)in(?)China,the(?)emission(?)level(?)of(?)particulate(?)matter(?)is(?)becoming(?)increasingly(?)strict,and(?)the(?)emission(?)of(?)particulate(?)matter(?)in(?)power(?)plants,steel(?)industry,building(?)materials(?)industry,and(?)other(?)industries(?)has(?)been(?)required(?)to(?)reach(?)ultra-low(?)emission(?)level.Further(?)reduction(?)of(?)particulate(?)matter(?)from(?)industrial(?)flue(?)gas(?)is(?)of(?)great(?)significance(?)to(?)winning(?)the(?)blue(?)sky(?)defense(?)war.Electrostatic(?)precipitation(?)is(?)an(?)important(?)method(?)for(?)the(?)efficient(?)removal(?)of(?)particulate(?)matter(?)from(?)industrial(?)flue(?)gas,and(?)has(?)wide(?)application(?)prospects(?)in(?)power,steel,cement,building(?)materials,nonferrous(?)metals,and(?)other(?)industries.Electrostatic(?)precipitation(?)is(?)a(?)complex(?)physical(?)process(?)involving(?)gas(?)ionizationelectron/ion(?)formation-ion(?)transport,and(?)particle(?)charge-particle(?)transport-particle(?)deposition(?)in(?)flue(?)gas(?)under(?)the(?)action(?)of(?)an(?)electric(?)field.Efficient(?)charge(?)and(?)migration(?)of(?)particles(?)is(?)the(?)key(?)to(?)improving(?)particle(?)removal(?)efficiency.However,electrons,ions,and(?)charged(?)particles(?)interact(?)with(?)the(?)electric(?)field-ion(?)density(?)fieldflow(?)field(?)during(?)the(?)transport(?)process.For(?)example,the(?)particle(?)charge(?)changes(?)the(?)electric(?)field(?)distribution,the(?)momentum(?)exchange(?)between(?)the(?)ion(?)charge(?)and(?)gas(?)molecules(?)exists,etc.It(?)manifested(?)as(?)particle-induced(?)air(?)gap(?)breakdown,ion(?)wind,and(?)other(?)phenomena,which(?)is(?)called(?)the(?)charge(?)effect.Among(?)them,the(?)charge(?)effect(?)of(?)charged(?)particles(?)and(?)ions(?)was(?)the(?)fundamental(?)reason(?)for(?)the(?)influence(?)of(?)their(?)charge(?)on(?)corona(?)discharge,particle(?)charging,particle(?)migration,particle(?)deposition,and(?)other(?)processes.With(?)the(?)application(?)of(?)electrostatic(?)precipitator,although(?)a(?)large(?)number(?)of(?)investigations(?)on(?)particle(?)removal(?)enhancement(?)have(?)been(?)reported,the(?)properties(?)of(?)combustion(?)flue(?)gas(?)have(?)become(?)complex(?)and(?)diverse,and(?)the(?)impact(?)of(?)the(?)charge(?)effect(?)on(?)particle(?)removal(?)is(?)becoming(?)increasingly(?)obvious.Therefore,this(?)study(?)focused(?)on(?)a(?)series(?)of(?)problems(?)caused(?)by(?)the(?)charge(?)effects(?)of(?)particles(?)and(?)ions(?)during(?)electrostatic(?)precipitation,and(?)the(?)charge(?)effect(?)and(?)regulation(?)in(?)electrostatic(?)precipitation(?)were(?)investigated(?)by(?)combining(?)theory,experiment,and(?)simulation.First,the(?)model(?)coupling(?)charged(?)particles(?)and(?)the(?)electric(?)field(?)was(?)established,and(?)the(?)local(?)enhancement(?)effect(?)of(?)the(?)electric(?)field(?)around(?)the(?)particle(?)was(?)revealed.Taking(?)the(?)particle,the(?)relative(?)permittivity(?)of(?)80,as(?)an(?)example,the(?)maximum(?)electric(?)field(?)strength(?)around(?)the(?)particle(?)could(?)reach(?)2.94(?).Moreover,the(?)mechanism(?)of(?)the(?)effect(?)of(?)the(?)local(?)enhancement(?)of(?)the(?)electric(?)field(?)on(?)the(?)particle(?)charging(?)process(?)was(?)further(?)clarified.It(?)was(?)found(?)that(?)the(?)particles(?)have(?)the(?)maximum(?)charge(?)in(?)the(?)electric(?)field,and(?)the(?)effective(?)strengthening(?)method(?)of(?)particle(?)charge(?)was(?)proposed.On(?)this(?)basis,an(?)experimental(?)platform(?)for(?)particle(?)optical(?)detection(?)was(?)established.For(?)the(?)charge(?)effect(?)of(?)transported(?)particles,this(?)study(?)revealed(?)the(?)dual(?)effects(?)of(?)particle(?)space(?)charge(?)on(?)the(?)discharge,clarified(?)the(?)phenomenon(?)of(?)air(?)gap(?)breakdown(?)throughout(?)the(?)entire(?)discharge(?)space(?)developed(?)from(?)local(?)gas(?)ionization(?)on(?)the(?)particle(?)surface,and(?)obtained(?)the(?)particle(?)charge(?)and(?)transport(?)characteristics(?)under(?)the(?)condition(?)of(?)gas(?)breakdown.For(?)the(?)charge(?)effect(?)of(?)the(?)deposited(?)particles,the(?)particle(?)deposition(?)characteristics(?)under(?)the(?)influence(?)of(?)the(?)particle(?)charge(?)effect(?)were(?)studied,and(?)the(?)formation(?)and(?)fracture(?)process(?)of(?)particle(?)chains(?)on(?)the(?)surface(?)of(?)the(?)collection(?)plates(?)were(?)revealed.The(?)growth(?)of(?)particle(?)chains(?)was(?)an(?)important(?)reason(?)for(?)the(?)gas(?)breakdown(?)and(?)particle(?)re-entrainment.Second,the(?)evolution(?)of(?)ionic(?)wind,formed(?)by(?)ion(?)charge(?)transport(?)in(?)the(?)electric(?)field,was(?)studied(?)by(?)PIV(?)technology.The(?)effects(?)of(?)applied(?)voltage(?)and(?)inlet(?)velocity(?)on(?)the(?)formation(?)of(?)ion(?)wind(?)were(?)revealed,and(?)it(?)was(?)found(?)that(?)the(?)maximum(?)velocity(?)of(?)ionic(?)wind(?)can(?)exceed(?)10(?)m/s.A(?)multi-process(?)coupling(?)electrostatic(?)precipitation(?)model(?)was(?)further(?)combined,and(?)the(?)effects(?)of(?)high-speed(?)ionic(?)wind(?)on(?)the(?)gas(?)flow(?)disturbance,particle(?)migration,and(?)deposition(?)in(?)the(?)plate-type(?)and(?)honeycomb-type(?)electrostatic(?)precipitators(?)were(?)studied.It(?)was(?)found(?)that(?)the(?)ionic(?)wind(?)promoted(?)the(?)migration(?)of(?)particles(?)to(?)the(?)collection(?)plates,and(?)the(?)maximum(?)Y-direction(?)velocity(?)of(?)the(?)1.0(?)μm(?)particle(?)size(?)could(?)be(?)enhanced(?)to(?)197.50(?)cm/s.However,it(?)also(?)caused(?)the(?)uneven(?)distribution(?)of(?)deposited(?)particles,particles(?)were(?)significantly(?)deposited(?)in(?)upstream(?)of(?)the(?)electrode(?)tips(?)and(?)significantly(?)reduced(?)in(?)downstream.Based(?)on(?)the(?)mechanism(?)of(?)ion(?)wind(?)effect(?)on(?)particle(?)migration(?)and(?)deposition(?)in(?)different(?)regions,the(?)distributions(?)of(?)ion(?)wind(?)acceleration,vortex,and(?)reflux(?)regions(?)in(?)the(?)flow(?)field(?)were(?)clarified,and(?)the(?)divisional(?)regulation(?)method(?)based(?)on(?)the(?)ionic(?)wind(?)distribution(?)was(?)proposed.Finally,based(?)on(?)the(?)analysis(?)of(?)the(?)particle(?)and(?)ion(?)charge(?)effects,the(?)particle(?)removal(?)enhancement(?)through(?)charge(?)effect(?)regulation(?)was(?)further(?)studied.For(?)the(?)problem(?)of(?)low(?)removal(?)efficiency(?)of(?)fine(?)particles,the(?)correlation(?)between(?)the(?)electrode(?)configuration(?)and(?)corona(?)discharge(?)and(?)particle(?)removal(?)was(?)revealed,and(?)the(?)enhanced(?)particle(?)removal(?)method(?)based(?)on(?)the(?)electrode(?)configuration(?)regulation(?)was(?)proposed,which(?)effectively(?)minimized(?)the(?)adverse(?)effect(?)of(?)the(?)particle(?)charge(?)effect.For(?)problems(?)such(?)as(?)gas(?)breakdown(?)and(?)re-entrainment(?)within(?)deposited(?)particles,five(?)patterns(?)for(?)particle(?)re-entrainment(?)in(?)an(?)electric(?)field(?)were(?)revealed,and(?)a(?)new(?)type(?)of(?)collection(?)plate(?)was(?)proposed.This(?)collection(?)plate(?)could(?)realize(?)the(?)efficient(?)removal(?)of(?)particles,and(?)inhibit(?)gas(?)breakdown(?)and(?)re-entrainment(?)within(?)deposited(?)particles.For(?)the(?)long-needle(?)electrode(?)and(?)the(?)arista(?)electrode,the(?)maximum(?)removal(?)efficiency(?)could(?)be(?)increased(?)by(?)11.5%(?)and(?)6.1%,respectively,and(?)the(?)amount(?)of(?)re-entrainment(?)was(?)reduced(?)by(?)85.2%(?)and(?)79.1%,respectively.Moreover,the(?)effect(?)of(?)the(?)layout(?)between(?)the(?)discharge(?)electrode(?)and(?)the(?)collection(?)plate(?)on(?)the(?)electric(?)field(?)distribution(?)and(?)particle(?)removal(?)was(?)studied,and(?)the(?)electric(?)field(?)partition(?)design(?)method(?)was(?)proposed.By(?)the(?)methods(?)of(?)local(?)strengthening(?)of(?)the(?)electric(?)field(?)and(?)overall(?)optimization(?)of(?)the(?)electrostatic(?)field,the(?)particle(?)charges(?)of(?)1.0(?)μm,2.5(?)μm,and(?)5.0(?)μm(?)were(?)increased(?)by(?)14.4%,11.7%,and(?)5.6%,respectively,and(?)the(?)removal(?)efficiency(?)was(?)increased(?)by(?)123.6%,117.2%,and(?)51.4%,respectively.The(?)results(?)of(?)this(?)study(?)are(?)conducive(?)to(?)strengthening(?)the(?)knowledge(?)of(?)electrostatic(?)precipitation,and(?)providing(?)key(?)theoretical(?)and(?)methodological(?)support(?)for(?)the(?)efficient(?)and(?)stable(?)removal(?)of(?)particulate(?)matter(?)from(?)various(?)industries.