The lighting with sufficient illumination and the air supply and exhaust system that can ensure the health of employees are with the vigorous development of China's auto industry. More and more automobile factories are put into operation, and the total amount of energy consumed in the automobile production process is also increasing. Painting is the process with the largest energy consumption in automobile production. This paper studies the automobile painting equipment. Grasp its energy usage. Targeted energy-saving measures are proposed and applied, which have achieved cost savings while reducing the environmental load, resulting in good economic and social benefits. 1 Introduction of automobile coating equipment The process equipment used for coating electrophoresis, middle coating and surface coating in turn and drying them respectively can be divided into pretreatment equipment, electrophoresis equipment, paint spraying room, drying room, paint conveying equipment, conveying equipment, Workplace etc.
1 Pre-processing equipment
The main function of pretreatment is to remove impurities such as iron powder and oil stains on the surface of the body in white. And attach a layer of phosphating film on the surface of the steel plate. After pre-treatment, the chemicals attached to the car body need to be washed with pure water before entering the electrophoresis process. The pre-treatment process is generally carried out in the tank body, and the tank liquid needs to maintain a certain temperature, so usually The circulation and spraying of the tank liquid in the supporting boiler system requires the use of various types of pumps. In addition, the iron powder removal device, the oil removal device, the phosphorus removal slag removal device and the pure water device also consume a lot of energy.
12 Electrophoresis equipment
The pre-treated car body enters the electrophoresis tank and is plated with electrophoresis paint. In the swimming production, high-power equipment such as paint circulation pump, water washing spray pump, UF ultrafiltration device, pure water device, and paint heat exchange device are used. In addition, large-scale equipment is required. The rectifier provides DC power for the electrophoresis process. The energy consumption of the entire electrophoresis equipment accounts for about 25% of the entire painting workshop.
1.3 Spray booth
In order to ensure the quality of spraying. The temperature and humidity of the spray booth need to be controlled within a certain range, especially for water-based paints. The allowable range of temperature and humidity fluctuations is very small. Therefore, the air conditioning system of the spray booth needs to be equipped with high-power heating, cooling and humidification modules. In addition, the spray booth also installs large The exhaust fan discharges the exhaust gas produced by spraying to the outdoor spray booth. The lower part of the spray booth is a circulating water tank or a dry adsorption system to separate the overspray paint mist that is not attached to the car body in order to improve the working conditions. More and more spray booths are equipped with robots for automatic spraying. The energy consumption of spray booths accounts for about 40c of the entire paint shop.
1.4 Drying room
The main function of the drying room is to provide heat energy. Evaporate the solvent in the heat-curable paint coated on the surface of the car body, cross-link the resin to form a film, or solidify the sealant, UBC and other materials, and play the role of car body sealing and stone attack prevention. At present, most car coatings The heating method of circulating hot air used in the drying room is under the action of the circulating fan, and the air in the drying room enters the heat exchanger. Exchange heat generated by burning natural gas, liquefied petroleum gas or diesel. Then back to the drying room, the energy consumption of the drying room equipment is second only to the electrophoresis equipment and the spray booth equipment.
1.5 Other equipment
The paint conveying equipment is mainly the equipment that uses the pump to convey the paint to the paint spraying room. The water-based paint needs to use the heat changer for heat preservation during the conveying process. The conveying equipment is responsible for moving the car body from one process inside the painting to the next process. It runs through the entire process of automobile painting. The conveying equipment is generally composed of chains, elevators, moving machines, friction wheels, roller beds, etc. The workplace is mainly used for coating grinding, polishing, repair, sealant, PVC coating and other operations field needs
2 Equipment energy saving measures
The electric energy consumed by the pre-treatment equipment, electrophoresis equipment, spray booth and drying room accounts for nearly 90% of the total energy consumption of the painting workshop. If the energy-saving transformation of the above four kinds of equipment is realized. It will play a key role in reducing the overall energy consumption of the paint shop. The energy saving solutions for these four types of equipment will be discussed below.
2.1 Energy-saving measures for pre-treatment equipment
According to the characteristics of many pumps in the pretreatment equipment. Motor frequency conversion system can be used. Reduce the energy consumption when the pump is running. In addition, the washing and spraying pump is set up to be interlocked with the automatic detection device of the vehicle body. The above measures can minimize the energy loss of the water pump. The use of new pre-treatment chemicals can also achieve the effect of energy saving of the equipment, such as the use of a degreaser with a good degreasing effect at a lower temperature. The temperature of the bath can drop. The load of the boiler can also be reduced. The effect of silane on the surface treatment of steel plate can reach the level of phosphating. Because the silane treatment is carried out at room temperature. Therefore, the consumption of heat energy can be greatly reduced
22 Energy saving measures for electrophoresis equipment
The working principle of electrophoresis equipment is similar to that of electroplating. The electricity consumption of the rectifier is the most in the electrophoresis equipment. The use of ICBT (insulated gate bipolar transistor) rectifier can realize the independent control of the voltage of more than ten segments. Compared with conventional two-stage or three-stage voltage-controlled thyristor rectifiers. Energy efficiency can be improved by more than 10%, similar to pre-processing equipment. Electrophoresis equipment also uses a lot of water pumps because the electrophoresis circulating pump needs to run 24 hours a day. After installing the frequency conversion system, the energy saving effect will be more obvious during production. The pump works under the power frequency state. And when not in production. The pump operates at low frequency. Ensure that the solid content in the paint does not deposit after installing the inverter. The high-pressure pump of the UF device and the pure water device will adjust the output power according to the pressure of the UF membrane and the ultrafiltration membrane permeate. To achieve the purpose of energy saving, the paint heat exchange device originally used solenoid valve and bypass to adjust the flow of cold and hot water. By using the frequency conversion device, this adjustment can be realized by adjusting the speed of the pump
2.3 Energy saving measures of spray booth
After the spray booth is turned on, once the process conditions of temperature and humidity are reached. It needs to be put into production immediately. Otherwise, there will be energy loss in dry operation, but it will be affected by the experience of equipment startup personnel and changes in ambient temperature and humidity. The spray booth usually reaches the process conditions 10 to 15 minutes before production starts and uses computer control. By collecting outside air temperature and humidity data.
After the correlation calculation with the temperature and humidity set in the spray booth. The best time to start the air conditioner can be obtained. Then perform automatic or manual equipment start-up operation according to the time after optimization calculation. The time for the temperature and humidity of the spray booth to reach the set value can be controlled within ±2 minutes of the production start time. Because the temperature, humidity and cleanliness of the outside air are in a state of change, the surface cooler, humidification pump and feeder of the air-conditioning equipment are in a state of change. The negative port of the air fan is also in a state of change. After the inverter is installed, the flow of the conveying medium can be controlled by adjusting the operating frequency of the fan and the water pump, so as to meet the adjustment of temperature, humidity and air volume, and reduce the use of electric energy. The interior is divided into purging area, manual spraying area, robot spraying area and inspection area, among which the robot spraying area has no personnel to work. without compromising safety. The content of volatile organic compounds in the air can be set higher accordingly. The exhaust air from the purging area, manual spraying area and inspection area can be sent to the robotic spraying area for recycling after being filtered. At present, the dry spray booth technology using lime powder to absorb volatile organic compounds in exhaust gas has entered the application stage. This technology can realize the recycling of exhaust gas in all areas of the painting room. The recycling of exhaust gas greatly reduces the power consumption of the air conditioner in the spray booth.
2.4 Energy saving measures of drying room
The principle of drying room startup time optimization is similar to that of air conditioners. The computer will calculate the best ignition time of the drying room according to the set temperature of the standby area of the drying room and the completion time of heating, and then output the command to start the burner. In this way, the start-up time of each drying room can be delayed by 10 to 15 minutes. The production of painting is not carried out when the workers are eating. Therefore, the drying room equipment is basically in an idle state. At this time, the energy saving is mainly realized by setting the low combustion state of the drying room. When there is no car body into the drying room. Reduce the combustion power of the burner through the control program. Reduce the air volume of circulating hot air in the drying room, and automatically return to normal combustion before production starts again
state. After the car body leaves the drying room, it needs to enter the cooling section for cooling. By installing the vehicle body detection device, when no vehicle body passes through the cooling section, the cooling fan will automatically stop running. In winter, the indoor temperature is relatively low. The cooling fan can be turned off.
2.5 Energy-saving measures for other equipment
Replacing pneumatic or hydraulic pumps with electric pumps can greatly reduce the energy consumption of paint mixing equipment, and at the same time, it can prevent the appearance of conveying pulses and improve the spraying quality. The energy saving of conveying equipment mainly focuses on reducing the ineffective operation of equipment in a car-free state. And the use of efficient Zhaoyin "responsible editor: Cao Mingming]
Lamps, recycling of air-conditioning condensate to cooling towers, and humidification, dust-proof and cooling in workshops can all play an effective energy-saving role.
3 Energy saving effect
By implementing the above energy-saving measures. The power consumption of painting and producing a car can be reduced by more than 15%. Natural gas consumption can be reduced by more than 10%. A factory with an annual production capacity of 100,000 vehicles will save millions in energy costs every year.
After the automobile painting equipment adopts energy-saving measures. While achieving huge benefits. It can also reduce the workload of employees and make the human-machine relationship more reasonable. Promoting equipment energy conservation activities can greatly stimulate the enthusiasm of employees, improve energy conservation awareness, increase energy conservation knowledge, and respond to the country's call for "constructing a conservation-minded society" with practical actions.