The pollution of painting production lines generally includes exhaust gas, wastewater, waste residue, and noise. At present, the exhaust gas from painting production lines in China mainly comes from pre-treatment, spray painting rooms, leveling rooms, and drying furnaces. The pollutants emitted generally include the following categories:; Organic solvents that can form photochemical smog, paint volatiles that emit foul odors, thermal decomposition products and reaction products, acid and alkali mist, dust generated during shot blasting, and dust in paint mist. The use of coatings that do not contain organic solvents or have low organic solvent content is the most effective way to solve organic solvent pollution. It is recommended to minimize the amount of organic solvents used and reduce the amount of organic solvent waste gas treatment. Waste gas containing high concentrations of organic solvents should be centrally treated and diluted before being discharged into the atmosphere; For the high concentration and low air volume organic solvent waste gas emitted from the drying and solidification furnace in the production line, combustion method, catalytic combustion method, and adsorption method are usually used for treatment.
The wastewater mainly comes from degreasing, phosphating, passivation wastewater generated during pre-treatment of painting, and wastewater containing electrophoretic paint generated during cathodic electrophoresis. The wastewater generated from the spray booth and cleaning of water-based intermediate coatings, and the wastewater regularly discharged from the circulating water of the topcoat spray booth. Generally, all wastewater is collected in the basement and treated separately according to the type of wastewater. Neutralization, sedimentation, filtration, and discharge of acidic and alkaline wastewater; Treat wastewater containing hexavalent chromium (Cr6-) using electrolysis and chemical reduction methods; Both water-based paint and solvent based paint wastewater are treated with paint mist coagulants, and paint residue is automatically discharged. The treated wastewater is further recycled, and the paint residue is burned or treated together with other industrial waste.
The paint mist coagulant iwaterA is mostly composed of medium molecular weight cationic polymers with extremely high charges, which can generate strong attraction to paint droplets. When the paint droplets are "captured" and adsorbed, it uses its different polar affinities to completely wrap and penetrate the paint droplets, destroying the functional groups of the coating, completely eliminating its stickiness, and driving the wrapped and broken paint droplets to float up.
The main sources of noise come from fans and transportation equipment, so we must choose fans and transportation equipment that meet the noise requirements on the production line. It is best to install sound-absorbing materials inside the painting workshop. The control system of the painting production line has been continuously improved with the development of the times, requiring the control system to become more and more reliable. So the electrical control of the coating production line is generally controlled by multiple control, which can be controlled by various electrical cabinets or by the central room for full line control. The central control room and drying oven are generally equipped with microcomputers, which can accurately control the temperature of each area of the drying and curing furnace. The central control room can be equipped with a TV monitor to display and record the temperature rise and fall curves, and can also set and modify parameters at any time to adjust the temperature according to different workpiece sizes and coating colors. The tank solution can be controlled by a thermocouple. All motors on the painting production line are generally equipped with dual protection and interlocked with the main control. If any motor fails, the sub control cabinet and central control room can alarm. If the equipment fails, the entire line can automatically shut down to ensure safe operation.