Minimum inlet pressure of reciprocating compressors
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I have a question regarding compressor operation: when nitrogen is used for purging the system, the inlet pressure drops to 0 MPa. Does this have any impact on the compressor? The outlet pressure is around 0.12 MPa.
When the gauge pressure (the value shown on the pressure gauge) is 0, if the inlet is an open container, it corresponds to atmospheric pressure and there is no issue; however, if the inlet is a closed container, a negative pressure is created, which is dangerous.
It should have little impact; the compression ratio is only 2.2, which is acceptable
During displacement, the inlet is connected to the nitrogen line; if the pressure is zero, it indicates that there is insufficient nitrogen. This has no effect on the compressor itself, but it may cause the pressure in the nitrogen system to become too low, which, as mentioned on the second floor, can have an impact on the entire installation or the factory.
Controlling the inlet pressure depends on whether the compression ratio exceeds the design value, whether the motor power is too high, and whether there are significant differences in the compression ratios across various stages, which could lead to overheating or overpressure in certain stages.
This post was last edited by YAN*NHAN on 2009-8-5 at 21:28. The inlet pressure at the first stage of a reciprocating compressor should generally not be too high; an inlet pressure of around 0.48 MPa poses a risk of motor overload. A decrease in inlet pressure is not a major issue; when it drops below 0 MPa, the load on the compressor motor actually tends to decrease (of course, it also depends on whether the compression ratio remains within the designed range). However, such a condition is not within the normal operating range; it may be acceptable for short-term use, but it is incorrect for long-term operation. The compressor cannot be regarded as a universal power device. If it is to operate for a long time, a vacuum pump should still be added before the compressor; of course, a safety valve must be installed on the vacuum pipeline to prevent accidental operation.
If the system always operates at an inlet pressure of 0 MPa and an outlet pressure of around 0.12 MPa, it is recommended to use rotary vane, water ring, or liquid ring compressors, as they are inexpensive and easy to use.
Controlling the inlet pressure depends on whether the compression ratio exceeds the design value, whether the motor power is too high, and whether there are significant differences in the compression ratios across various stages, which could lead to overheating or overpressure in certain stages.