The waste gas from coating and painting is mainly caused by volatile organic compounds VOCs, benzene series, particles, odor gas and other pollution factors, and is mainly generated during surface treatment such as automobile manufacturing, furniture industry, ship manufacturing, container manufacturing, metal products, mechanical equipment, aviation and railway manufacturing.
The main pollution sources of paint waste gas are divided into two categories: 1 Particles are generated from dust generated during basic surface treatment, spray mist during spraying operation, putty layer and grinding dust of intermediate coating; 2. VOCs organic waste gas is generated from solvent volatilization during paint mixing, solvent volatilization during coating / coating, spray mist separation after spraying, solvent volatilization during drying and curing, and new volatiles generated by drying and curing reaction.
1. Main source of spraying waste gas in painting workshop
The waste gas from the paint spraying workshop mainly comes from the paint mist volatilized by the organic solvent contained in the paint during the spraying process and the volatile waste gas generated during the drying process, which is called volatile organic compounds (VOCs), and the main components are benzene, toluene, xylene, etc. Generally speaking, VOCs (organic waste gas) produced during the use of intermediate coating, surface coating and cleaning solvents. Specific to the production workshop, the most organic waste gas is produced in the paint spraying room, drying room, paint mixing room, drying room, etc., while the components of waste gas produced by different workshops are different.
2. Waste gas treatment process of spraying industry
According to the composition structure of paint waste gas, the general treatment process and equipment flow: gas collection system - pretreatment spray dust system - waste gas purification device system. In the design of pretreatment system, multi-stage spray washing or higher dust removal equipment (mechanical dust removal is recommended); In the waste gas purification process, if the air volume is large or the concentration is high, concentration can be considered and catalytic thermal combustion process equipment can be adopted; If the concentration is low, the air volume is medium or lower, activated carbon adsorption and desorption can be used.
① Spray tower + photocatalysis + nano adsorption decomposition
② Spray tower + plasma equipment + fan
③ Activated carbon adsorption desorption catalytic combustion equipment
3. Characteristics and advantages of coating and painting waste gas process
Catalytic thermal combustion process is the first treatment technology under the working conditions of stable and complex waste gas composition, high waste gas concentration and high dust content in the coating industry. Its purification effect is very ideal, the purification effect is relatively complete, and there are no or few secondary pollutants. If the heat can be recycled in the treatment process, it can save a lot of operating costs. Activated carbon adsorption and desorption is only for those projects with low concentration and small air volume, so as to reduce the first cost of environmental protection equipment in the enterprise from the perspective of the enterprise. It is also more cost-effective compared with catalytic thermal combustion in the later stage of operation. It is a good choice for coating and painting waste gas treatment process in addition to catalytic thermal combustion.
