Loss of control at the screw compressor stage
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Dear seniors, I have a question: Our unit uses screw compressors manufactured in Dalian as the ammonia compressors, and we have been operating it in manual mode. It has recently been found that the compressor stage can load itself. When the machine was stopped to remove the solenoid valve, a brown, hard plastic piece was found stuck inside it. After replacing the lubricant and filter, the solenoid valve was reinstalled and the oil pump was started; the pressure level kept rising, reaching over 100. It happened the same way after repeating it 2 times; every time I opened it, there was still that same piece of hard plastic. I wonder what’s going on here. :(
In our company, the ammonia compressors used to have the same issue; even the newly replaced units exhibit this problem. Has this situation persisted all along, or was it normal at first? Also, is it possible that the load cannot be removed? Or it’s not easy to remove
It worked normally for three years at first, and then that’s what happened
Well, there was no problem before. How should I put it? The screw compressors we use here are usually sent back to the factory for repair. We have indeed encountered the situation of automatic loading mentioned by you, but we didn’t pay much attention to it; the compressors could still function normally. However, when it came to unloading, the load couldn’t be removed, so we had to shut down the compressor under load, which certainly causes damage to the compressor. But sometimes it’s possible to remove the load after all (though this happens very rarely). One downside of automatic loading up to 100% is that the suction pressure becomes too low, often reaching -0.1 MPA, which causes significant damage to the mechanical seal. In our experience, with ammonia compressors, the mechanical seal needed to be replaced every little over a year
Is a four-way valve or four solenoid valves used for loading and unloading the slide valve? This situation may occur due to internal leakage caused by damage to the internal components of the four-way valve; replacing the four-way valve or switching to four solenoid valves will resolve the issue
It is certain that the shaft seal will be damaged; if the low pressure on the inlet side causes gas to escape from the oil, cavitation can easily occur on the tooth surfaces on the suction side over time
I found the reason; the gauge installed the solenoid valve in the wrong direction. Speechless