Four factors affect the discharge capacity of screw air compressor

2020-07-11 23:26:43 keepwin

What factors will affect the actual discharge capacity of screw compressor?

Answer: the theoretical displacement of screw compressor depends on the volume between teeth, number of teeth and speed. The volume between teeth is determined by the geometry of the rotor. For the compressor, the actual displacement is less than the theoretical displacement, the possible reasons are as follows:

1) Leakage. 

There is no contact between the rotors and between the rotors and the shell during operation, and there is a certain gap, so gas leakage will occur. When the pressure increases, the gas will leak to the suction pipe and the meshing groove, which will reduce the exhaust volume. In order to reduce the leakage, a sealing tooth is made on the tooth top of the driven rotor, a sealing groove is opened on the tooth root of the driving rotor, and the ring or strip-shaped sealing teeth are also processed on the end face. If these sealing lines are worn, the leakage will increase and the exhaust volume will decrease;

2) Inspiratory state. 

Screw compressor is a positive displacement compressor, the suction volume remains unchanged. When the suction temperature increases or the suction pressure decreases due to the excessive resistance of the suction pipe, the density of the gas decreases and the mass displacement of the gas is reduced accordingly;

Four factors affect the discharge capacity of screw air compressor

3) Cooling effect. 

During the compression process, the temperature of the gas will rise, and the temperature of the rotor and the casing will also rise accordingly. Therefore, in the process of suction, the gas will be heated by the rotor and the casing and expand, so the suction volume will be reduced accordingly. Some rotors of screw air compressor are cooled by oil, and the casing is cooled by water. One of the purposes is to reduce the temperature. When the exhaust temperature is not good, the cooling effect will be reduced;

4) Speed. 

The displacement of screw compressor is directly proportional to the rotational speed. However, the speed will change with the voltage and frequency of the power grid. When the voltage decreases (for asynchronous motors) or the frequency decreases, the speed will decrease and the air volume will decrease.