Concurrent VOC and Aerosol Removals from Air Stream by Flow Stabilized Non-Thermal Plasma-Adsorbent-Catalyst Hybrid Systems

Jen-Shih Chang

McIARS and

Department of Engineering Physics McMaster University

Baltic Workshop, September,Griswold

Table of Contents

� Health Impact of VOCs: Cl-type vs HC type VOCs

� Conventional VOC treatment techniques

� Plasma VOC treatment

� Plasma- Catalysis/Adsorbent VOC treatment

� Concluding remarks

VOCs Problem

� Sick Building Syndrome -Indoor Air Quality

� Heath Problem via Air, Soil and Ground Water

� Chemical Industry vs Semiconductor Plants

� Clean Room-Air Re-circulation� PFCs in Semiconductor & Power Industries

VOC world wide 2009

Indoor Air Problems

Bounding Energy and Ionization Potential

Thermal Oxidation Treatment of VOCs

9

Regenerative Thermal Oxidizers (RTOs)

Figure 3: Schematic of RTO Process

Ideal Oxidation Reaction of VOCs:

Indoor Air Cleaning

� Baking of Room-3 to 7 days

� Continuous Force Air Re-circulation

� Indoor Air Cleaner-4 to 10hrs treatment with small flow rates –ideal for plasma systems

�Ozonizer based system is no longer in market and must be remove or control ozonegeneration below 0.1-0.2 ppm

�Ozone killer-MnO2‘

� Combined with air conditioning, water cluster ion generators, EHD flow (electric wind) gas blower etc.

Plasma Air Cleaner is on the market for past 10 years

Commercial Air Cleaner and Incinerator Cleaning System (Mizuno 2000)

Commercial Plasma Air Cleaners

Vibration Vibration Vibration Vibration ∝∝∝∝ HeatHeatHeatHeat

SolidSolidSolidSolid LiquidLiquidLiquidLiquid GasGasGasGas

PlasmaPlasmaPlasmaPlasma

VibratingVibratingVibratingVibrating

atomatomatomatom

Kinetic energy Kinetic energy Kinetic energy Kinetic energy ∝∝∝∝ HeatHeatHeatHeat

atomatomatomatomorororor

moleculemoleculemoleculemolecule

atomatomatomatom

dipoledipoledipoledipole 0(10)K0(10)K0(10)K0(10)K 0(100)K0(100)K0(100)K0(100)K

LatentLatentLatentLatentHeatHeatHeatHeat

LatentLatentLatentLatentHeatHeatHeatHeat

IonizationIonizationIonizationIonizationorororor

AttachmentAttachmentAttachmentAttachment0(100(100(100(103333----101010104444)K)K)K)K

Formation ofFormation ofFormation ofFormation ofPlasmaPlasmaPlasmaPlasma

What Is PlasmasWhat Is PlasmasWhat Is PlasmasWhat Is Plasmas

e

e

ee

ElectronElectronElectronElectron

AttachmentAttachmentAttachmentAttachment

Negative IonNegative IonNegative IonNegative Ion

IonizationIonizationIonizationIonization

Positive IonPositive IonPositive IonPositive Ion

HighHighHighHigh LowLowLowLow HighHighHighHigh LowLowLowLow HighHighHighHigh LowLowLowLow

PressurePressurePressurePressureGas Gas Gas Gas TemperatureTemperatureTemperatureTemperature

Electron Electron Electron Electron TemperatureTemperatureTemperatureTemperatureTypeTypeTypeType

TypicalTypicalTypicalTypicalApplicationsApplicationsApplicationsApplications

Nuclear FusionNuclear FusionNuclear FusionNuclear FusionPlasmaPlasmaPlasmaPlasma

ThermalThermalThermalThermalPlasmaPlasmaPlasmaPlasma

NonNonNonNon----ThermalThermalThermalThermalPlasmaPlasmaPlasmaPlasma

Low PressureLow PressureLow PressureLow PressurePlasmaPlasmaPlasmaPlasma

---- SemiconductorSemiconductorSemiconductorSemiconductor---- Lump and LasersLump and LasersLump and LasersLump and Lasers---- DisplayDisplayDisplayDisplay

---- EnergyEnergyEnergyEnergy---- MilitaryMilitaryMilitaryMilitary

---- Solid Waste TreatmentsSolid Waste TreatmentsSolid Waste TreatmentsSolid Waste Treatments---- CoatingCoatingCoatingCoating---- Ceramic ProcessingCeramic ProcessingCeramic ProcessingCeramic Processing---- Water TreatmentsWater TreatmentsWater TreatmentsWater Treatments---- Cutting & WeldingCutting & WeldingCutting & WeldingCutting & Welding

---- Air Pollution ControlAir Pollution ControlAir Pollution ControlAir Pollution Control---- Waste TreatmentWaste TreatmentWaste TreatmentWaste Treatment---- Polymer CoatingPolymer CoatingPolymer CoatingPolymer Coating---- Polymer TreatmentsPolymer TreatmentsPolymer TreatmentsPolymer Treatments

Type of Industrial PlasmasType of Industrial PlasmasType of Industrial PlasmasType of Industrial Plasmas

Electron Impact Reactions and Electron Energy Distribution

� Thermal Plasma: Ionization dominated by Thermal Ionizations� Non-Thermal Plasma: Ionization dominated by Electron Impact

Ionizations

Around Tg = 2000 –3000 K

Effectiveness of Reactions-Ionic or Radical Reaction

Mechanism of Plasma Processes

Ion Induced Particle Formations (Chang 1996)

Plasma Density

Electron Temperature

Gas TemperatureElectric

FieldTreatment Flue

Gases

Power Supply&

ReactorImprovements

Electron Beam Very High Extremely High Low Very Low Acid Gases, VOCs DC → PulseEnergy

Efficiency

Barrier Discharge (silent/surface)

High Medium Low MediumOxidation of VOCs

or Acid Gases

Parallel plate↓

Trench, Pylamid

PressureDrop

Barrier Discharge(ferro-electric)

Low High Low Very HighPFCs, Oxidation of

VOCsShape of PelletsSphere → Hollow

Pressure drop &Energy

Efficiency

Pulsed Corona High Medium Low High VOCs Pulsed corona↓

Pulse Power

ElectronEnergy

Pulsed Power Very High High Medium High Acid Gases

Capillary High Low Medium Low VOCs

DC → AC/DC StabilityFlow StabilizedCorona

LocallyHigh

LocallyHigh

Low HighAcid Gases, VOCs,

Toxic Gases

Arc/PlasmaTorch

ExtremelyHigh

LocallyHigh

ExtremelyHigh

LowODS/VOCs*Toxic Gases

Lower PowerEnergy

Efficiency

RF Discharge High Medium High Low ODS/VOCs* Inductive → CapacitiveEnergy

Efficiency

MicrowaveDischarge

High Medium Medium Medium ODS/VOCs* Cavity → Torch Temperature

Table 1 Plasma parameters for gaseous pollution control plasma devices (*Waste gas destructions)

Fig. 3. Schematics of dielectric barrier discharge reactors: a) silent discharge; b) surface discharge; c) and d) packed bed; and e) trench reactor.

Fig.2 Experimental apparatus.

Experimental Apparatus� Air-VOCs

� Packed-bed (BaTiO3) reactor

� Carbon or Zeolite filter

� Oxidation or reduction catalyst

� FTIR#1 upstream of

reactor#2 downstream

of reactor#3 downstream

of filter

catalyst

VOCs

Plasma Catalytic or Adsorption Processes

The destruction effeciency for o-xylene and TCE in a gas mixture (111 ppm of xylene and 111 ppm of TCE) using the pulsed corona reactor for gas flow rate of (a) 0.7 L/min and (b) 1.0 L/min.

Toluene Decomposition

Cl-VOC Compounds

Pulsed Corona Corona Torch

CCl4 removal from Air Stream

Aerosol Formation

Example for plasma processes comparison chart for plasma-catalyst/adsorbent system

Oxidation /Reduction Catalyst

Capillary Wall and Pellets Act as Removable Filters

Energy Efficiency VOC Removal of dc vs Pulse

Why catalysis/adsorbent works under low gas temperature non-thermal plasmas

�Catalytic material site activation by a plasma vibrationally/rotationally and electronically excited molecules

�Prevent de-sorption of

pollutant but slowdownkinetic energy of molecules

114

114

85

85

mesh: 100 x 100

Units: [mm]13

pellets

reactor packed with pelletElectrodes

Schematics of catalytic packed bed reactor.

Pellet with catalyst

Catalytic material site

Powersupply

Pump

Environmentalchamber

Outlet VOCmeter

RH&Temp. transmitterMultimeter

Air inlet

C

Bubbly column

Digital oscilloscope

Probe

HV probe

Currenttransformer

Reactor

AC 7 kHzor Pulse 200 Hz

Vacuum

IR camera

Computer

Schematic of experimental

apparatus.

Adsorption of Gas and the Effect of Plasmas

Ceramics can adsorb various gases

andPlasma generated heat effects?

-1000

-800

-600-400

-2000

200

400

600800

1000

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]

Q [

nC]

-1000

-800

-600-400

-2000

200

400

600800

1000

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]

Q [

nC]

t = 0 [min.] t = 6 [min.]

-1500

-1000

-500

0

500

1000

1500

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]

Q [

nC]

-1000

-800

-600-400

-2000

200

400

600800

1000

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]

Q [

nC]

-2500

-2000

-1500

-1000

-500

0

500

1000

15002000

2500

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]

Q [

nC]

-1000

-800

-600

-400

-200

0

200

400

600800

1000

-8 -6 -4 -2 0 2 4 6 8

Vpp [kV]Q

[nC

]

Lissajous figures at (a) PV = 9, RH =

20%,(b) (b) PV = 6.5,

RH = 50% and(c) PV = 6.5, RH =

80%.

(a)

(b)

(c)

-8-6-4-202468

-100 -80 -60 -40 -20 0 20 40 60 80 100

Time [µs]

Vpp

[kV

]

-200-150-100-50050100150200

I [

mA

]

V

I

T = 1 [min.]

T = 4 [min.]

T = 10 [min.]

T = 1 [min.]

T = 4 [min.]

T = 11 [min.]

Transient IR thermal images at (a) PV = 8.5, RH 20%, (b) PV=6, RH 80%.

(a)(b)

0

50

100

150

200

250

300

0 5 10 15 20Time [min.]

Te

mp

. [o C

]

RH 20%

RH 80%

Reactor surface temperature transient for various reactors.

Principle of Plasma-Catalyst/Adsorbent System

Activation of catalysis site

Advantage Disadvantage

Catalytic material siteRotational Excitation of Molecule O(100)K

Why Non-Thermal Plasma-Catalysis Works

Vibrational Excitationof Molecules O(1000)K

Electronically Excitationof Molecules O(104)K

Plasma / Energetic Electron

Translation TemperatureO(100)K ?Normally by Gas Heating

Concluding Remarks� VOCs Plasma-Catalyst-Adsorbent

techniques now commertical for indoor air equipments, however, for larger Industrial system only limited commertialization has been aceived for 1000 Nm3/h level multi-module system.