Equipment spraying includes automotive/motorcycle/container/parts manufacturing and many other sparying. Spraying exhaust gas (the exhaust gas produced when spraying paint) whose main components are benzene, toluene, xylene and some dust particles, most of the spray exhaust gas also contains acetylatate, butyl ketone, isopropyl alcohol and some ether substances. At the present stage, most enterprises use activated carbon adsorption/desorption and catalytic combustion process for the exhaust gas treatment.
1. Pre-processing
Organic exhaust gas may contain a small amount of dust, which will clog the activated carbon micropores, affecting the adsorption effect. So a pre-treatment progress must be added before the gas into activated carbon. The equipment of pre-treatment is dry filter, which is divided into two levels, with characteristics of large dust capacity, small resistance etc.
2. Activated carbon adsorption
After the previous pre-treatment, the exhaust gas is passed into the activated carbon adsorption/desorption box for adsorption treatment. Activated carbon with a large surface area adsorbs the organic solvent on its surface, which has achieved the effect of removing organic matter from the exhaust gas and purifying the gas. The treated clean gas is emitted at high altitude through the fan and chimney.
3.Desorption stage of activated carbon
When the activated carbon adsorption reaches saturation, switch to the desorption mode and start the desorption fan to desorb the adsorption bed. The fresh air introduced by the desorption fan is first heated through the heat exchanger and the electric heating chamber. Before the fresh air enters the activated carbon bed, it is needed to be heated to nearly 120℃. After the carbon bed is heated, the solvent adsorbed by the activated carbon is desorbed out.
4. Catalytic combustion
The desorbed exhaust gas flow is small and the concentration is high. The gas will be sent to the heat exchanger by fan, and then into the preheater. Under the action of the electric heater, the temperature of the gas is increased to about 250-300 ° C, and then enters the catalytic combustion bed. Organic gas is oxidized to CO2 and H2O under the action of the catalyst flameless combustion, while releasing a large amount of heat, the temperature will be further increased. And then the high temperature gas through the catalytic combustion chamber (in front of the heat exchanger) to preheat the untreated organic gas; The gas out of the heat exchanger and then through the fresh air inlet of the heat exchanger to desorbed fresh air for heating. For saving the energy, the electric heating equipment can stop heating after the two exchangers are working normally. Finally, the final gas is emitted high through the chimney.
