There are many factors that affect the displacement of centrifugal compressor. Except for the connection with design, manufacture and installation, the main factors that can affect the displacement of compressor are:
1) the air filter is blocked or the resistance increases, which causes the pressure of the compressor's suction to decrease. When the outlet pressure remains unchanged, make the compressor pressure ratio increase. According to the performance curve of the compressor, when the pressure ratio increases, the displacement will decrease;
2) the pipeline of the air separation plant is blocked, and the resistance increases or the valve breaks down, which causes the exhaust pressure of the air compressor to rise. Under the condition of constant suction pressure, the pressure ratio increases, resulting in the reduction of exhaust volume;
3) the blocking or resistance of the compressor intermediate cooler increases, which causes the reduction of exhaust volume. However, the situation of blocking in different positions is different: if the gas side resistance of the cooler increases, only the internal resistance of the machine will be increased, which will reduce the efficiency of the compressor and the exhaust volume; if the resistance of the water side increases, the circulating cooling water will decrease, which will make the gas cooling bad, thus affecting the next level of suction and reducing the air discharge of the compressor;
4) bad sealing causes gas leakage. Including: ① internal leakage, that is, the air running between levels. Reverse the compressed gas, and then conduct the second compression. It will affect the working condition at all levels, increase the low pressure grade ratio and decrease the high pressure grade ratio, which will make the whole compressor deviate from the design working condition and reduce the displacement; ② external leakage, that is, air leakage from the shaft seal to the outer shell. Although the amount of absorption remains unchanged, a part of the compressed gas leaks out, which naturally causes the reduction of exhaust volume;
5) cooler leakage. If the first level leakage, because the water side pressure is higher than the gas side pressure, the cooling water will enter the air side channel, and will be further carried into the impeller and the diffuser by the airflow. After a certain period of time, it will cause scaling and blocking, which will reduce the air flow. If the second and third level cooler leaks, because the pressure of the air side is higher than that of the water side, the compressed air will leak into the cooling water and run away, which will reduce the displacement;
6) the decrease of the frequency or voltage of the power grid causes the decrease of the rotation speed of the motor and compressor and the decrease of the exhaust volume;
7) when the temperature of any primary suction increases and the density of gas decreases, it will also lead to the reduction of suction.
