I. Overview

 

As an important power equipment, air compressors are widely used in many fields such as machinery manufacturing, chemicals, cement and building materials, mines, power plants, and transportation construction. Screw air compressors account for most of the compressor market share due to their advantages of stability, high efficiency, easy maintenance, and low noise. Based on our country’s industrial design concept, when selecting air compressors in general factories, the maximum load will be increased by 10-40%, resulting in the actual loading rate of most industrial and mining screw air compressors being between 50%-80%. between. According to statistics, the electricity consumption of air compressors accounts for about 10%-30% of the total electricity consumption of industrial enterprises. It can be seen that the energy-saving transformation of the screw compressor is a matter of economic value and practical significance. The air compressor control system currently produced and designed by our company is based on the CV3100 series inverter combined with the Plot MAM-880 series controller, which fully considers the various working conditions and actual operating trajectories of the screw air compressor, and eliminates pressure fluctuations. , Constant pressure gas supply, process intervention and other technical means, save power consumption to the greatest extent, and save 15%-50% of operating costs on average. The effect is very significant.

 

Second, the shortcomings of the traditional air compressor

 

①Large power frequency starting inrush current Although the main motor adopts Y-△ decompression starting, the starting current is still very large, which has a large impact on the power grid, which is likely to cause instability of the power grid and threaten the safety of other electrical equipment.

 

②The pressure is unstable and the degree of automation is low. The traditional air compressor has a low degree of automation, and the output pressure is adjusted by the control of the loading and unloading valve and the regulating valve. The adjustment speed is slow, the fluctuation is large, the accuracy is low, and the output pressure is unstable.

 

③Large equipment maintenance The air compressor has a large power-frequency starting current, up to 5-8 times the rated current. The working mode determines that the loading and unloading valve will inevitably operate repeatedly, the components are easy to age, the power-frequency high-speed operation, the bearing wear is large, and the equipment maintenance is large.

 

④Large noise Continuous high-speed operation of power frequency, additional pressure exceeding the required working pressure, repeated loading and unloading, will directly cause high noise of power frequency operation.

 

⑤Serious waste of electric energy When loading and unloading air compressors, energy is mainly wasted in the following aspects. After the electric energy consumption pressure during loading reaches the required working pressure, the control method determines that the pressure will continue to rise until the unloading pressure. During the pressurization process, the compressor will generate more heat and noise, and consume more electricity. On the other hand, before the high-pressure gas enters the pneumatic components, its pressure needs to be reduced by a pressure reducing valve, which also consumes energy. When the power consumption during unloading reaches the unloading pressure, the air compressor automatically opens the unloading valve, causing the motor to run idly, causing serious energy waste. The power consumption when the air compressor is unloaded accounts for about 35% to 50% of the full load, which shows that the traditional air compressor has obvious energy saving space.

 

Third, the benefits of energy-saving transformation

 

①The starting current of the air compressor is small, and there is no impact on the power grid. The energy-saving control cabinet with CV3100 series inverter and Plot MAM-880 series controller can control the compressor to start and load the current to rise gently without any impact; It can make the motor realize soft stop, avoid the harm caused by excessive reverse current, and help to extend the service life of the equipment.

 

②The output compressed gas pressure is stable. After adopting the energy-saving control cabinet of the CV3100 series inverter and Plot MAM-880 series controller, the pressure of the gas in the gas supply pipeline can be monitored in real time to keep the pressure of the gas in the gas pipeline constant. Improve production efficiency and product quality.

 

③The amount of equipment maintenance is small. The starting current of the air compressor is small, less than 2 times the rated current. The loading and unloading valve does not need to be operated repeatedly. The energy-saving control cabinet controls the air compressor to automatically adjust the motor speed according to the air consumption. The operating frequency is low, the speed is slow, and the bearing wear is small. , The service life of the equipment is extended, and the maintenance workload is reduced.

 

④ The overall noise of the unit is reduced by more than 15%. The energy-saving control cabinet provides energy according to the gas demand without too much energy loss. The motor running frequency is low, and the mechanical rotation noise is therefore reduced. Due to the way the energy-saving control cabinet adjusts the motor speed, there is no need to repeatedly load , Unloading, the noise of frequent loading and unloading is gone, and the noise caused by the continuous pressurization and unstable air pressure also disappears.

 

Four, conclusion

 

In a word, after adopting the energy-saving control cabinet of CV3100 series inverter and Protech MAM-880 series controller, not only can save a considerable amount of electricity cost, extend the service life of compressor, but also realize the purpose of constant pressure air supply. , Improve production efficiency and product quality.