Destruction Technology During VOCs Treatment-1

Destruction technology

Combustion method

Combustion method refers to the oxidation and combustion of flammable volatile organic waste gas under certain conditions to generate non-toxic, harmless or low-harm substances, and then achieve the purpose of purifying waste gas. Direct combustion, thermal combustion and catalytic combustion are the three most widely used combustion methods in the industry.

Direct combustion method

Direct combustion of VOCs as fuel is called direct combustion method. The temperature requirements of the direct combustion method are relatively high, generally above 1100 °C. Moreover, there are certain restrictions on the oxygen concentration. Low oxygen concentration will lead to incomplete combustion of VOCs, which is likely to cause secondary pollution; too high oxygen concentration will indirectly lead to the reduction of the concentration of combustibles, which will not reach the limit of ignition concentration.

The direct combustion method is easy to operate, has no requirements on the type and nature of the treated gas, and the degradation rate can reach more than 98%. However, due to the high energy consumption and potential safety hazards, this method has been rarely used in recent years.

Thermal combustion method

Thermal combustion is generally used when the concentration of VOCs is low. The difference from the direct combustion method is that the organic waste gas needs to be preheated, and the combustion temperature is greatly reduced, generally at 350 to 600 C, which belongs to flameless combustion, which reduces energy consumption and increases safety.

The equipment commonly used in the industry can be divided into thermal oxidizer without heat recovery, thermal oxidizer with partition heat exchanger, and regenerative thermal oxidizer (RTO).

Catalytic combustion method

Catalytic combustion method refers to the use of catalysts to reduce the activation energy required for the oxidation of volatile organic compounds, increase the reaction rate, and make the oxidation reaction proceed at a lower temperature (200-400°C).

According to different heat energy recovery methods, catalytic oxidizers can also be divided into non-heat recovery, partition type, and regenerative catalytic oxidizers (RCO). Compared with RTO, the fixed bed of the regenerator in RCO has an additional layer of catalyst.

The effect of catalytic combustion mainly depends on the properties of the catalyst. How to prepare highly active and multi-selective catalysts is one of the research focuses of domestic and foreign researchers.