Working principle
Plasma generation mechanism
The core of a plasma scrubber is to generate low-temperature plasma through dielectric barrier discharge (DBD) or corona discharge technology. When a sufficiently high AC voltage (usually 5-30kV, frequency 50Hz-100kHz) is applied, the gas in the electrode gap is broken down, forming a large number of micro discharge channels.
During the discharge process, electrons obtain energy from the electric field (with an average energy of 1-10 eV), and these high-energy electrons collide with gas molecules, triggering the following main reactions:
• Electron collision excitation: e+M → M *+e
• Electron collision ionization: e+M → M ⁺+2e
• Electron dissociation: e+AB → A+B+e
• Attachment reaction: e+AB → AB ⁻
Degradation process of pollutants
Organic pollutants in exhaust gases undergo complex physicochemical processes and are degraded in plasma environments. The main degradation pathways include:
1. Direct electron collision: High energy electrons collide directly with pollutant molecules, causing them to excite, ionize, or dissociate.
2. Free radical reaction: Active free radicals such as · OH, · O, · N generated by discharge react with pollutants.
3. Ozone oxidation: The O3 generated by discharge undergoes an oxidation reaction with pollutants.
4. UV photolysis: The UV radiation generated during the discharge process causes pollutants to undergo photolysis.
Technical features
Compared to traditional exhaust gas treatment technologies, plasma scrubbers have the following characteristics:
|
Comparison items |
Plasma |
Thermal combustion |
Activated carbon adsorption |
|
Processing temperature |
Room temperature |
700-800℃ |
Room temperature |
|
Energy consumption |
Low |
Tall |
Middle |
|
Remove efficiency |
85-99% |
95-99% |
60-90% |
|
Secondary pollution |
Nothing |
NOx |
Waste activated carbon |
|
Floor area |
Small |
Big |
Middle |
Comparison between plasma scrubbers and traditional technologies
Core technological advantages:
1. Broad spectrum: It can simultaneously handle multiple types of VOCs, including alkanes, alkenes, aromatic hydrocarbons, oxygen-containing organic compounds, etc.
2. Adaptability: Strong adaptability to fluctuations in exhaust gas concentration, capable of treating low concentration (<100ppm) exhaust gas.
3. Safety: Operated at room temperature, with no risk of fire or explosion.
4. Modularization: It can be flexibly combined according to processing capacity, making it easy to expand.
Technical indicators
Performance parameters
|
Parameter name |
Numerical range |
Remark |
|
Handling air volume |
1000-50000 m³/h |
Customizable |
|
VOCs removal rate |
≥90% |
Depending on the composition |
|
Odor removal rate |
≥95% |
NH₃、H₂S, etc |
|
Input voltage |
AC 380V ± 10% |
Three-phase five-wire |
|
Discharge voltage |
5-30 kV |
Adjustable |
|
Discharge frequency |
50 Hz - 100 kHz |
Adjustable |
|
Power density |
5-50 W/L |
Depending on concentration |
|
Equipment resistance |
<500 Pa |
Low resistance |
Structural parameters
|
Parameter name |
Specifications |
Material |
|
Reactor shell |
Carbon steel/stainless steel |
Q235/SUS304 |
|
Discharge electrode |
Stainless steel needle/wire |
SUS316 |
|
Grounding electrode |
Stainless steel plate |
SUS304 |
|
Dielectric layer |
Ceramic/Quartz |
Al₂O₃/SiO₂ |
|
Insulating material |
Polytetrafluoroethylene |
PTFE |
|
High voltage power supply |
High frequency inverter |
IGBT module |
|
Control system |
PLC automatic control |
Siemens/Mitsubishi |
Application field
Plasma scrubbers are used for exhaust gas treatment in the following industries:
Printing and packaging industry
The main components of ink waste gas generated during printing, lamination, and coating processes are toluene, xylene, ethyl acetate, etc.
Painting and spraying industry
Dealing with paint mist and organic solvent waste gas generated during the painting and baking process, including alcohols, ketones, esters, etc.
Chemical and pharmaceutical industry
The process exhaust gases emitted from reaction vessels, distillation towers, drying equipment, etc. are complex and diverse in composition.
Electronic semiconductor industry
Process special gases and organic waste gases generated by photolithography, etching, cleaning, and other processes.
Food processing industry
Dealing with oil fumes and odors generated during processes such as frying, baking, and fermentation.
Equipment selection
According to the processing air volume and pollutant concentration, plasma scrubbers are divided into the following standard models:
|
Model |
Handling air volume |
Installed capacity |
Dimensions (mm) |
|
PS-1000 |
1000 m³/h |
3 kW |
1200×800×1500 |
|
PS-3000 |
3000 m³/h |
8 kW |
1800×1000×1800 |
|
PS-5000 |
5000 m³/h |
12 kW |
2200×1200×2000 |
|
PS-10000 |
10000 m³/h |
22 kW |
2800×1500×2200 |
|
PS-20000 |
20000 m³/h |
40 kW |
3600×2000×2500 |
|
PS-50000 |
50000 m³/h |
90 kW |
5000×2800×3000 |
Selection precautions:
• The particulate matter content in the exhaust gas should be less than 5mg/m ³, and if it is too high, pre-treatment is required
• The relative humidity should be less than 80%. If it is too high, dehumidification treatment is required
• The exhaust gas temperature should be less than 60 ℃. If it is too high, it needs to be cooled down
• Halogen containing exhaust gas requires special design to prevent corrosion
• Explosion proof measures must be taken for flammable and explosive exhaust gases
