Centrifuge surge problem
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I need some expert guidance! Phenomenon: After the centrifuge (2MCL456/2BCL458) was shut down for routine maintenance and restarted, a noise was emitted by the two-stage outlet check valve when the pressure rose to 2.1–2.7 MPA; the operating point of the centrifuge fluctuated significantly within the operating range (it did not exceed the anti-surge line, so the anti-surge valve did not activate). Suspicion: During pressure increase, the overall air volume of the centrifuge is lower than under normal operation, but the operating point is in the normal range; it is possible that both the low air volume and high pressure also have an impact. Preliminary assessment: There is a problem with the second or third compression stage; either the exhaust from the second stage or the intake air in the third stage is not flowing properly, and the gas is drawn back after being expelled (similar to the surge phenomenon that occurs in the second or third stage alone). However, since both the first and second stages share one impeller, and both the third and fourth stages share another impeller, there is no issue with the impellers themselves. The problem might lie in the diffusers of the second or third stage ? ? ), causing the two-stage outlet check valve to move back and forth and producing a loud noise. The cause of the problem is unknown. The judgment might be incorrect; I seek guidance from experts! ! ! !
The abnormal data of the centrifuge lies in the changes in the pressure at the second-stage outlet and the pressure at the third-stage inlet; 15 sets of data were compared. Normal condition: The pressure at the outlet of stage 2 is slightly higher than the pressure at the inlet of stage 3. Abnormal condition: The pressure in stage 2 is lower than the pressure at the inlet of stage 3 (by 0.1 MPA). Phenomenon: The pressure in stage 2 drops suddenly (by about 0.05 MPA), while the pressure in stage 3 rises suddenly (by about 0.05 MPA); gas flows in reverse, causing the check valve to activate and producing a loud noise (clicking…hissing…bang). The pressure in each section fluctuates accordingly, as does the flow rate and the operating point (as long as it remains below the surge line, the surge valve does not activate).
It’s a Shenyang Blower Machinery machine, right? You haven’t described the process, so it’s difficult to judge.
It’s from Shenmu; I already mentioned the model numbers: 2MCL456/2BCL458. There’s no change in the processing process, nor in the components of the process gas or the process parameters. It seems to be a problem with the unit itself, and it’s difficult to identify the cause; it’s quite confusing. The process is a standard compression process: imported gas is compressed in four stages, with a cooler and a separator in each compression stage; that’s about it
You already mentioned that the abnormal noise is coming from the check valve; stop and check whether the check valve opens properly and whether it is stuck.
The equipment is fine; it’s poor process control that causes the check valve to operate repeatedly.