02,05,2026 16 views
1.活性炭吸附法
The activated carbon adsorption method for exhaust gas treatment equipment utilizes the micropores inside activated carbon to concentrate one or several components in the exhaust gas on the solid surface, thereby separating them from other components. Activated carbon adsorption is an economically effective process for the treatment of volatile organic components, with high adsorption efficiency and a wide range of applications. The process of treating exhaust gas but regenerating activated carbon is more complex and requires higher investment.
2. Combustion method
The process of using combustion methods to eliminate harmful gases, vapors, or smoke in exhaust gas treatment equipment and turn them into harmless substances is called combustion purification. The chemical reactions that occur during combustion purification are mainly combustion oxidation and thermal decomposition at high temperatures. The combustion and oxidation of organic gaseous pollutants result in the generation of CO2 and H2O. The combustion purification methods are divided into direct combustion and thermal combustion.
3. Catalytic combustion method
Catalytic combustion in exhaust gas treatment equipment is a typical gas-solid phase catalytic reaction, which essentially involves deep oxidation with the participation of reactive oxygen species. In the process of catalytic combustion, the role of the catalyst is to reduce the activation energy, and at the same time, the catalyst surface has adsorption effect, which enriches the reactant molecules on the surface and increases the reaction rate, accelerating the progress of the reaction. With the help of catalysts, organic waste gas can undergo flameless combustion at lower ignition temperatures, and be oxidized and decomposed into CO2 and H2O, while releasing a large amount of heat energy. This process has high processing efficiency and no secondary pollution. However, this process has the disadvantages of high investment, certain requirements for the concentration of organic compounds in organic waste gas, and high requirements for management and operation level. Therefore, there are corresponding limitations in the selection process.
Thermal oxidation of organic waste gas treatment
The thermal oxidation system is a flame oxidizer that eliminates organic matter through combustion, with an operating temperature of up to 700 ℃ to 1000 ℃. This inevitably has high fuel costs, and in order to reduce fuel costs, it is necessary to recover the heat from the exhaust gas leaving the oxidizer.
There are two ways to recover heat: traditional wall to wall heat transfer and new non steady state thermal storage heat transfer technology.
Inter wall thermal oxidation is a method of capturing and purifying exhaust gas using tube or plate type inter wall heat exchangers. It can recover 40% to 70% of thermal energy and use the recovered heat to preheat the organic waste gas entering the oxidation system. The preheated exhaust gas is then passed through a flame to reach the oxidation temperature for purification. The disadvantage of inter wall heat exchange is that the heat recovery efficiency is not high.
Regenerative Thermal Oxidation (RTO) uses a new non steady state heat transfer method to recover heat. The main principle is to alternate the circulation of organic waste gas and purified exhaust gas, and capture heat to the maximum extent through multiple continuous changes in flow direction. The thermal storage system provides high thermal energy recovery for thermal oxidation/catalytic combustion. During a certain cycle, organic waste gas containing VOCs enters the RTO system and first enters the refractory thermal storage bed layer (which has been heated by the purified gas of the previous cycle). The waste gas absorbs thermal energy from the bed layer to raise the temperature, and then enters the oxidation chamber; VOCs are oxidized into CO2 and H2O in the oxidation chamber, and the exhaust gas is purified; The high-temperature purified gas after oxidation leaves the combustion chamber and enters another cold thermal storage bed layer, which absorbs heat from the purified exhaust gas and stores it (used to preheat the organic waste gas entering the system for the next cycle). And lower the temperature of the purified exhaust gas. After a certain period of time, the direction of gas flow is reversed, and organic waste gas enters the system from the bed. This cycle continuously absorbs and releases heat, and the thermal storage bed, which serves as a heat trap, also constantly changes its operation mode of inlet and outlet, resulting in thermal energy recovery. The heat recovery rate can reach up to 95%, and the VOC elimination rate can reach 99%.
Integrated technology (carbon adsorption+catalytic oxidation) for organic waste gas treatment
For high flow and low concentration organic waste gas, using the above single method for treatment is too expensive and uneconomical. The use of carbon adsorption has the advantage of treating low concentrations and atmospheric volumes. First, activated carbon is used to capture organic matter in the exhaust gas, and then a much smaller flow rate of hot air is used for desorption. This can enrich VOCs by 10-15 times, greatly reducing the volume of exhaust gas treatment and significantly reducing the scale of post-treatment equipment.
Send the concentrated gas to the catalytic combustion device, and utilize the characteristic of catalytic combustion that is suitable for treating higher concentrations to eliminate VOCs. The heat released by catalytic combustion can be preheated by a partition heat exchanger to reduce the energy requirements of the system by introducing desorbed gas into the carbon adsorption bed. This technology utilizes the characteristics of carbon adsorption to treat low concentrations and atmospheric volumes, as well as the advantages of catalytic bed treatment for moderate flow rates and high concentrations. Develop a highly effective integrated technology. Used for the treatment of high flow and low concentration organic waste gases in industries such as spray painting, printing, and shoe manufacturing.
Catalytic combustion of organic waste gas treatment
Catalytic combustion is a method similar to thermal oxidation for treating VOCs. It purifies organic matter by using precious metal catalysts such as platinum and palladium, as well as transition metal oxide catalysts, instead of flames. The operating temperature is half that of thermal oxidation, usually between 250 ℃ and 500 ℃. Due to the decrease in temperature, it is allowed to use standard materials instead of expensive special materials, greatly reducing equipment and operating costs. Similar to thermal oxidation, the system can still be divided into two types of heat recovery methods: partition type and thermal storage type.
Inter wall catalytic combustion involves installing a heat exchanger behind the catalytic bed, which not only lowers the exhaust gas temperature but also preheats organic waste gas containing VOCs, achieving a heat recovery rate of 60% to 75%. This type of oxidizer has long been used in industrial processes.
Regenerative Catalytic Combustion (RCO) is a new catalytic technology. It has the characteristics of RTO energy recovery and the advantages of low-temperature operation and energy efficiency in catalytic reactions. The catalyst is placed on top of the thermal storage material to achieve purification, and its heat recovery rate is as high as 95% to 98%. The key to the performance of RCO systems is the use of catalysts, such as precious metal or transition metal catalysts impregnated on saddle shaped or honeycomb shaped ceramics, which allow oxidation to occur at half the temperature of the RTO system, reducing fuel consumption and equipment costs.
Some countries have started using RCO technology for the elimination and treatment of organic waste gas, and many RTO equipment have begun to transform into RCO, which can reduce operating costs by 33% to 75% and increase exhaust gas flow by 20% to 40%.
