concurrent voc and aerosol removalsfrom air stream … · stabilized non-thermal...
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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
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
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
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
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.
Example for plasma processes comparison chart for plasma-catalyst/adsorbent system
Oxidation /Reduction Catalyst
Capillary Wall and Pellets Act as Removable Filters
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.
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.