What factors affect the displacement of centrifugal compressors

What factors affect the displacement of centrifugal compressors

1) The air filter is blocked or the resistance increases, causing the suction pressure of the compressor to decrease. When the outlet pressure is constant, the compressor pressure ratio is increased. According to the performance curve of the compressor, when the pressure ratio increases, the displacement will decrease;

2) The air separation equipment pipeline is blocked, the resistance increases or the valve fails, causing the exhaust pressure of the air compressor to increase. Under the condition of constant suction pressure, the pressure ratio increases, resulting in a decrease in exhaust volume;

3) The compressor intercooler is blocked or the resistance increases, causing the exhaust volume to decrease. However, the situation of blockage at different positions is different: if the air-side resistance of the cooler increases, only the internal resistance of the machine is increased, so that the compressor efficiency is reduced, and the displacement is reduced; if the water-side resistance increases, the cooling cycle is performed. The reduction of water volume makes the gas cooling poorly, which affects the suction of the next stage and reduces the discharge volume of the compressor;

4) Poor sealing, causing gas leakage. Including: ① internal leakage, that is, inter-stage blow-by. Rewind the compressed gas and perform a second compression. It will affect the working conditions of each stage, increase the pressure ratio of the low pressure stage and decrease the pressure ratio of the high pressure stage, which will cause the entire compressor to deviate from the design working condition and decrease the displacement; ②External leakage, that is, from the shaft end seal to the outside of the casing Air leak. Although the suction volume remains the same, some of the compressed gas leaks, which naturally causes the exhaust volume to decrease;

5) The cooler leaks. If the first stage leaks, because the water side pressure is higher than the air side pressure, the cooling water will enter the air side channel and be further entrained by the airflow into the impeller and diffuser. After a certain period of time, it will cause fouling and blockage, which will reduce the air flow. If the secondary and tertiary coolers leak, the compressed air will leak into the cooling water and run away because the air side pressure is higher than the water side, reducing the exhaust volume;

6) The frequency or voltage of the power grid drops, causing the speed of the motor and compressor to drop, and the exhaust volume is reduced;

7) The increase in the suction temperature of any stage and the decrease of the gas density will also cause the decrease of the suction volume.