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Energy-saving method for spray booth of automobile coating production line
In the organic waste gas treatment system, the circulating air method in the spray booth can reduce the exhaust air volume of the spray booth, thereby reducing the operation energy consumption of the organic waste gas treatment system. In addition, the use of RTO machinery or TNV machinery and equipment for heat recovery and utilization of the flash drying room, waste gas incineration treatment equipment, and heat recovery and utilization of organic waste gas can reduce the energy consumption of organic waste gas treatment and achieve the purpose of environmental protection and energy saving.
1. The method of circulating air in the spray booth
In our country’s traditional spraying production workshops, wet spray booths (Venturi or hydrocyclone) + newly upgraded exhaust air method are mostly used, that is, the air source used in the spray booth is clean and fresh air, the central air conditioning ventilation is disposable, and the exhaust has been No recycling. For the 3C1B and B1B2 processing technology, the spray booth is longer, and the exhaust air volume to be solved is large, so the operation consumes a lot of energy.
When the spraying workshop is under construction, the spray booth can choose to use circulating system air supply. In industrial workshops with manual hand repair and painting stations, part of the circulating system wind supply can be selected. The manual spraying section and manual repair section will be used for exhaust air. To the intelligent robot painting section, and its clear paint (finish) leveling section, reduce the air supply of the fresh air system; if it is a fully automatic robot electrostatic powder spraying, all circulating system air supply methods can be selected, that is, the intelligent robot painting section In addition to the circulating system air returned from the leveling, paint repair section, and air seal section, the exhaust air also includes the exhaust system of the spraying section.
Among them, the exhaust system circulation solution includes two methods: dry test cycle solution and wet test cycle solution. The moisture content of the gas discharged from the pre-paint preparation section, air curtain, drying room, etc. is not high, and it can be recycled by just filtering. System application, or paint spray room exhaust system solved by dry test paint mist collection equipment, because its cleanliness level (0.3Mg/m3) is qualified, it can be recycled directly, which is called dry cycle; and after wet test (Hand wash type) Paint mist collection equipment solves the problem of increased moisture content in the spray booth, which can only be recycled after dehumidification and temperature control. This is called wet test cycle; both dry test cycles and wet test cycles can only be removed The paint mist and fine particles in the exhaust system are basically incapable of removing VOC. Therefore, it is necessary to strictly control the VOC component in the spraying work fixture, that is, in the manual service spraying fixture, the VOC component should be controlled in the national defense safety and health license specifications Within the scope, the automatic spraying area (no man's area) should be operated below the fire safety concentration value (that is, below 25% of the flammable gas explosion lower limit concentration value).
2. Application of organic waste gas in flash drying room
For water-based paint spray paint production workshops, the color paint is generally water-based paint. After spraying, it needs to enter the water vapor drying oven for baking. The general temperature will be around 80°C. Gas is used as mechanical energy to heat the gas. The resulting organic waste gas is generally discharged directly into the air. With the improvement of the laws and regulations management system at the level of ecological environment protection in my country, clear requirements have been made for the VOC components in industrial waste gas, so the organic waste gas caused in the water vapor drying furnace also needs to carry out centralized incineration treatment. If the organic waste gas is immediately sent to the organic waste gas incineration treatment system software to ignite, the organic waste gas contains a low VOC concentration value, the exhaust volume to be solved is large, and the gas consumption is large; if this gas is combined with the spray room The organic waste gas is tightly combined, and the temperature of the mixed organic waste gas is relatively high, which can easily lead to the lack of efficiency of the extraction drum. In order to avoid reducing all the normal service life of the runner, the heat generated by the organic waste gas discharged from the flash drying room is generally used for the heating solution of the fresh air system.
Under normal conditions, the temperature of industrial waste gas in the flash drying room is around 80°C, and the flash drying fresh air system conducts heat transfer according to the plate heat exchanger, which promotes the specific temperature of the fresh air system to rise up to 25°C, thereby maintaining energy efficiency. Acquisition and rational use. In the whole process here, the temperature of industrial waste gas that has undergone reconditioning and tempering treatment is about 50℃, and it is mixed with the organic waste gas of the spray booth, which always promotes the temperature of the organic waste gas to obtain a small temperature increase, which is not easy The solution to the hazard drum is efficient. This kind of method can not only promote the temperature of flash-dried organic waste gas to drop sharply, but also reasonably reduce the composition of water vapor, avoiding the adverse effect of organic waste gas on the normal service life of the drum under the condition of high environmental humidity.
3. Utilization of calorific value of organic waste gas after incineration
There are two common types of organic waste gas incineration treatment equipment, R T O and TAR. They all ignite and dissolve the VOC in the organic waste gas according to the high temperature, and then produce carbon dioxide and water, and finally produce a clean vapor and then discharge it. However, because there are certain differences in the structure of RT O and TAR equipment, the temperature at the inlet and outlet of the two is different. Among them, the temperature of the first one can reach 110℃～130℃. , TAR temperature reaches 560℃. It must be emphasized that TAR is a very important part of TNV machinery and equipment. It is composed of engine combustion chamber, heat exchanger, burner and main flue gas control valve. The smoke and dust discharged from the sewage can be burned. The organic waste gas in the room is heated to increase the temperature, and the fresh air system entering the drying room is heated to solve the problem. Basically, when the organic waste gas treatment equipment is officially used, the 110℃～130℃ high temperature steam discharged by RT O, in most of the production workshops, the steam discharge is carried out according to a very immediate method. The steam is heated by a heat exchanger, and organic matter is also produced in the heat exchanger for a long time, which will cause certain harm to the high efficiency of the overall operation of the heat exchanger. For this matter, this type of vapor is generally sent to the paint residue solution area according to the pipeline, and the paint residue is air-dried according to the waste heat recovery, and the water content of the paint residue is reduced to the minimum level, so that the paint can be removed. Slag solves the cost control in very few cases.