Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Reduction of VOC Emissions from Paint-
Booth Operations Using Dielectric Barrier
Discharge
30th Environmental and EnergySymposium & Exhibition
San Diego, CAApril 7, 2004
Gregory D. HollandJohn N. Veenstra
Arland H. JohannesGary L. FoutchFreddie Hall
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Background
• The Oklahoma City Air Logistics Center (OC-ALC) conducts surface coating as regulated by 40 CFR 63.741 in maintenance paint booths at the facility. Volatile Organic Compounds (VOCs) are emitted as a result. While the emissions rate is currently well below the stationary major source threshold of 10 tons per year, these low emissions are the result of using low-VOC/low-solids paints.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Background
• The low-VOC/low-solids paint has performed and weathered poorly, and as a result, the planes require more frequent painting as well as constant touch-ups. An efficient method of emission treatment is desired to enable renewed use of the better performing high-VOC/high-solids paints.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Background
• The typical emissions control technique for surface coating spray booths is carbon absorption (average control efficiency = 90%). Carbon absorption has a fire potential in the carbon bed when high concentrations of ketones and alcohols are present as at TAFB. Furthermore, the painting operations at TAFB are not continuous but are of short duration. Due to this operational pattern, a technology with an “instant-on”, ”instant off” capability without a concurrent step-up in emissions would be the most efficient treatment for TAFB.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Background
• TAFB has commissioned the investigation of an innovative technology to meet plant and regulatory requirements. A Gas Phase Corona Reactor (GPCR), also known as a dielectric barrier discharge (DBD) or non-thermal plasma (NTP) reactor, is being designed to reduce VOC emissions from painting operations.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Project Goals
• Establish optimum operating conditions using bench-scale studies.
• Test capacity limits for design and cost of full-scale equipment.
• Collect statistically significant data to verify VOC destruction and determine operating costs.
• Two week operation test at Tinker AFB with greater than 90% removal of VOCs from stack exhaust.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Project Phases
• Phase I: Investigate operation of different reactor geometries. Verify destruction capabilities. Investigate operating variables using single-tube, bench-scale reactors.
• Phase II: Design pilot-scale reactor for 1,000 scfm (multi-tube design) and demonstrate unit at TAFB. Develop technology demonstration plan.
• Phase III: Test 1,000 scfm unit. Determine economic and scale-up factors for the plasma unit. Design full-scale reactor for 20,000 cfm.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Plasma Discharge Process
• High electric fields are used to generate high energy electrons (up to 10 eV) which collide with the gas molecules to create highly reactive ions and/or free-radicals.
• The dielectric barrier prevents the direct flow of current and prevents excess heating.
• Essentially no warm-up period required, allowing “instant on” capability.
• “On-the-fly” adjustment of power to handle variation in VOC loading
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Dielectric Barrier DischargeOuter Electrode Dielectric Barrier
Inner Electrode Plasma Zone
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Phase I
• Investigate operation of different reactor geometries.
• Verify destruction capabilities.
• Investigate operating variables using single plasma zone, bench-scale reactors.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Target components:– Toluene– Methyl Isobutyl Ketone– Butyl Acetate– Sec-Butyl Alcohol
– Methyl Propyl Ketone– Ethyl 3-Ethoxypropionate– 1,6-Hexamethylene
Diisocyanate
– Gas Mixture– Actual Stack Gas
Operating variables:– Reactor geometry
• Round, square, plate– Electric field strength
• 16-18 kV– Discharge frequency
• 200-400 Hz– Residence time
• 0.05-0.2 seconds– VOC concentration
• 35-250 ppm– Humidity
• 0-80% relative humidity
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
F T P
F T P
Air
Cyl
ind
er
FlowController
Tolueneand Heater
Thermocouple
PressureTransducer
FlowController
Thermocouple
PressureTransducer
Gas Chromatograph
AC Power SupplyVariable Potential &
FrequencyGround
Step-UpTransformer
Vent
Pla
sma
Rea
cto
r
Process Flow Diagram
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
AC
Ground
Reactor
IsolationAmplifierR3
Z1
R1
R2
DAC
112V
60
Hz
Tra
nsfo
rmer
Circuit Schematic for MeasuringPlasma Electrical Characteristics
10V
15k
V
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Flat Plate Reactor
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Square Tube Reactor
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Single Tube Reactor
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Single Tube Reactor
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Rea
ctor
Tur
ned
Off
Rea
ctor
Tur
ned
On
Initial Total Effluent Concentration
0
20
40
60
80
100
120
-5 0 5 10 15 20 25 30 35 40
Sample time (minutes)
PP
M
Sec-Butanol MIBK Toluene Butyl Acetate total effluent
Figure 3. Plot of destruction data (as concentration) for V” = 17 kVrms, f =
300 Hz, tres = 0.1 second, and rh = 0% (Run #04).
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Rea
ctor
Tur
ned
Off
Rea
ctor
Tur
ned
On
90% of Initial Concentration
Initial Concentration
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-5 0 5 10 15 20 25 30 35 40
Sample time (minutes)
Fra
ctio
n of
inle
t co
ncen
trat
ion
Sec-Butanol MIBK Toluene Butyl Acetate total effluent
Figure 4. Plot of destruction data (as a fraction of inlet conc.) for V” = 17 kVrms, f = 300 Hz, tres = 0.2 second, and rh = 70-80% (Run #40).
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Phase I Results
• Reactor geometry: Single dielectric barrier, annular gap.• Electric field strength: Greater destruction at higher electric
field strengths. • Discharge frequency: Greater destruction at higher discharge
frequencies.• Residence time: Greater destruction efficiency at higher
residence times.• VOC concentration: Greater destruction efficiency at higher
concentrations.• Humidity: Improves destruction efficiency of some components,
reduces destruction efficiency of others. Humid conditions improve overall destruction efficiency. May increase energy requirements.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Phase II
• Design pilot-scale reactor for treating 1,000 cfm (multi-tube design) and demonstrate unit at TAFB.
• Determine economic and scale-up factors for the plasma unit.
• Develop technology demonstration plan.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Phase II – Current Status
• Comparing energy consumption parameters of different size reactors to determine scaling factors:– Single-tube reactor with a 1 to 50 cm plasma zone.– 10-tube reactors with 1-cm or 5-cm plasma zones in each
tube.
• Difficulties measuring the secondary current – require customized circuitry.
• Economics will depend on energy requirements and final size.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
10-Tube Reactor
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Acknowledgments
• Oklahoma City – Air Logistics Center
• Center for Aircraft andSystems/Support Infrastructure
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Acknowledgments
• Vijay Kalpathi – Ph.D. student, Chemical Engineering
• Visalakshi Annamalai – M.S. student, Electrical Engineering
• Rajbarath.P – M.S. student, Environmental Engineering
• Elangovan Karuppasamy – M.S. student, Environmental Engineering
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Run #Sec. Volt.
(kV) Freq. (Hz)Residence Time (sec) RH (%)
Total Influent Conc. (ppm) Destr. (%)
Ave. Dest. (%)
1 17.0 300 0.2 0 77.3 92.0%2 17.0 300 0.2 0 76.2 91.2% 91%3 17.0 300 0.2 0 82.6 89.9%4 17.0 300 0.1 0 90.8 82.3%5 17.0 300 0.1 0 83.1 84.6% 83%6 17.0 300 0.1 0 81.6 82.3%7 17.0 300 0.05 0 89.6 73.4%8 17.0 300 0.05 0 88.3 69.2% 70%9 17.0 300 0.05 0 76.9 66.4%
Table 1. Summary of destruction data for residence time comparisons.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Run #Sec. Volt.
(kV) Freq. (Hz)Residence Time (sec) RH (%)
Total Influent Conc. (ppm) Destr. (%)
Ave. Dest. (%)
28 13.6 200 0.05 0 79.8 51.9%29 13.6 200 0.05 0 81.2 57.2% 56%30 13.6 200 0.05 0 79.2 59.2%7 17.0 300 0.05 0 89.6 73.4%8 17.0 300 0.05 0 88.3 69.2% 70%9 17.0 300 0.05 0 76.9 66.4%31 17.0 400 0.05 0 90.4 85.3%32 17.0 400 0.05 0 81.3 81.4% 83%33 17.0 400 0.05 0 88.4 82.9%
Table 2. Summary of destruction data for line operating frequency comparisons.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Run #Sec. Volt.
(kV) Freq. (Hz)Residence Time (sec) RH (%)
Total Influent Conc. (ppm) Destr. (%)
Ave. Dest. (%)
16 16.0 300 0.05 0 77.8 50.9%17 16.0 300 0.05 0 88.7 72.6% 64%18 16.0 300 0.05 0 89.9 69.8%7 17.0 300 0.05 0 89.6 73.4%8 17.0 300 0.05 0 88.3 69.2% 70%9 17.0 300 0.05 0 76.9 66.4%25 18.0 300 0.05 0 92.6 77.5%26 18.0 300 0.05 0 90.6 75.7% 76%27 18.0 300 0.05 0 91.5 75.5%
Table 3. Summary of destruction data for applied electric potential comparisons.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Run #Sec. Volt.
(kV) Freq. (Hz)Residence Time (sec) RH (%)
Total Influent Conc. (ppm) Destr. (%)
Ave. Dest. (%)
43 13.6 200 0.2 0 256.6 47.0% 47%46 13.6 200 0.2 0 157.3 57.3% 57%49 13.6 200 0.2 0 37.5 67.1% 67%
Table 4. Summary of destruction data for VOC concentration comparisons.
Reduction of VOC Emissions from Paint-BoothOperations Using Dielectric Barrier Discharge
Run #Sec. Volt.
(kV) Freq. (Hz)Residence Time (sec) RH (%)
Total Influent Conc. (ppm) Destr. (%)
Ave. Dest. (%)
1 17.0 300 0.2 0 77.3 92.0%2 17.0 300 0.2 0 76.2 91.2% 91%3 17.0 300 0.2 0 82.6 89.9%34 17.0 300 0.2 30-45 96.0 97.2%35 17.0 300 0.2 30-45 88.1 97.2% 97%36 17.0 300 0.2 30-45 81.6 97.3%40 17.0 300 0.2 65-80 91.1 97.4%41 17.0 300 0.2 65-80 87.9 96.0% 97%42 17.0 300 0.2 65-80 92.5 96.2%
Table 5. Summary of destruction data for relative humidity comparisons.