organic-waste-gas-vocs

- Main ingredients: Various volatile organic compounds, such as benzene, toluene, xylene, formaldehyde, acetone, ethyl acetate, alkanes, alkenes, etc. 
- Sources: Chemical production, coating, printing, pharmaceuticals, rubber and plastics processing, etc.

For organic waste gas, primarily composed of various volatile organic compounds (VOCs) from a wide range of sources, the following equipment can be used for treatment:

Activated Carbon Adsorption Equipment
- Principle: Activated carbon, with its rich microporous structure and large surface area, has a strong adsorption capacity for various VOCs. As organic waste gas passes through the activated carbon layer, VOC molecules are adsorbed on the surface, thereby purifying the waste gas. Once the activated carbon reaches saturation, it can be regenerated through hot air purging or water vapor desorption. The desorbed high-concentration organic waste gas can be further treated.
- Application: Suitable for treating low- to medium-concentration organic waste gas with high air volume. It has excellent adsorption performance for most common VOCs, such as benzene, toluene, xylene, formaldehyde, acetone, and ethyl acetate. However, for high-concentration waste gas, the activated carbon requires frequent replacement, resulting in high operating costs.

Catalytic Combustion Equipment
- Principle: Under the action of a catalyst (such as a precious metal catalyst like platinum or palladium, or a metal oxide catalyst), VOCs in organic waste gas undergo an oxidation reaction at a relatively low temperature (generally 200-400°C) to produce carbon dioxide and water. The catalyst reduces the activation energy of the reaction, facilitating the reaction while also reducing energy consumption.
- Applications: Suitable for treating low- to medium-concentration organic waste gas, it effectively treats various VOCs, including alkanes, alkenes, benzene series, aldehydes, and ketones. It is particularly well-suited for continuously emitted waste gas. This equipment offers high purification efficiency (over 95%), low energy consumption, and zero secondary pollution. However, it is sensitive to catalyst poisoning substances, such as dust and heavy metals, in the waste gas, requiring pretreatment.

Regenerative Thermal Oxidation (RTO) Equipment
- Principle: After entering the RTO equipment, organic waste gas is first preheated in a regenerator. It then enters the oxidation chamber, where the organic components are oxidized and decomposed into carbon dioxide and water at a high temperature (approximately 760°C). The resulting high-temperature gas then passes through another regenerator, releasing heat to heat the regenerator, which is then used to preheat incoming waste gas, achieving heat recovery. By switching the inlet and outlet channels, the regenerator alternately absorbs and releases heat.
- Applications: It can treat high-concentration, high-volume organic waste gas. It has a high treatment efficiency for all types of volatile organic compounds, achieving a purification efficiency of over 99%. Furthermore, due to heat recovery, operating costs are relatively low. However, the equipment investment is relatively large, requiring a large floor space, and is more suitable for treating organic waste gas with a relatively stable composition.

Condensation Recovery Equipment
- Principle: Based on the characteristic that substances have different saturated vapor pressures at different temperatures, VOCs in organic waste gas are supersaturated by lowering the temperature or increasing the system pressure, thereby condensing them into a liquid form and separating them from the waste gas for recovery.
- Application: Suitable for treating high-concentration, high-boiling-point organic waste gas, such as alkanes and benzene series. For low-concentration waste gas, the high energy required to lower the temperature or increase the pressure makes this less economical. Condensation recovery equipment can recover and reuse organic solvents, offering certain economic benefits, but it requires high pressure and low-temperature resistance.

Biological Treatment Equipment (Biological Filters, Biotrickling Filters, etc.)
- Principle: Utilizing microbial metabolism, VOCs in organic waste gas serve as a carbon source and energy source for microbial growth. Microbial degradation converts these VOCs into carbon dioxide, water, and microbial cell matter. In a biofilter, waste gas passes through a filter layer containing microorganisms, where VOCs are adsorbed and decomposed by the microorganisms. A biotrickling filter, on the other hand, sprays a nutrient solution onto the microbial-containing media to maintain microbial activity and purify the waste gas.
- Applicable Applications: Suitable for treating low- to medium-concentration, biodegradable organic waste gases, such as ethanol, acetone, and ethyl acetate. This method offers low operating costs and no secondary pollution, but treatment efficiency is significantly affected by factors such as waste gas composition, temperature, humidity, and pH, and is less effective for treating difficult-to-biodegrade organic matter.

In practical applications, a single device or a combination of multiple devices is typically selected for organic waste gas treatment based on multiple factors, including its specific composition, concentration, air volume, emission patterns, and economic costs. For example, for low-concentration, high-volume organic waste gas, activated carbon adsorption and concentration can be used first, followed by catalytic combustion. For high-concentration waste gas, organic solvents can be recovered through condensation, followed by deep purification using RTO.