Seeking help to start a centrifugal compressor
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I would like to ask everyone: We have a centrifugal compressor used for circulating the gas in the pipeline. Since it is a circulating pipeline, it is not desirable to drain the medium in order to avoid wasting it when starting up, but at the same time the circulating pipeline is not unobstructed during startup. When it’s time to start the machine now, open all of the return pipes of the compressor, set the inlet valve to a slight opening degree, and close the exhaust valve. This allows the compressor to start up and load under the influence of the return flow; once a minimum load is reached and stability is achieved, then the exhaust valve is opened to allow high-pressure gas to enter the circulation pipes and start the circulation process. I don’t see what’s wrong with that. Additionally, the loading of the centrifugal compressor can range from 0 to the designed value. According to the manufacturer’s specifications, there is a minimum current requirement; is it necessary to reach this minimum current value immediately upon startup, even for a minimal amount of suction flow? Is it possible to increase the load gradually, starting from 0?
The method you mentioned above should work, but be sure to equalize the pressure in both the compressor and the downstream system before opening the circulation valve; open the valve only after the pressure equalization is complete. The normal start-up of a centrifugal compressor requires a minimum load, which corresponds to a minimum current; the load can only be increased gradually from this minimum current value.
Thank you. What do you mean by the latter system? Do you refer to the pipeline behind the circulation valve? We want to wait until the compressor stabilizes at the minimum current level, then close the return valve while opening the exhaust valve, in order to gradually build up the pressure throughout the entire circulation system. Is this what you mean by pressure equalization? Then, after the check valve is fully closed, adjust the settings of the circulation system to gradually load the compressor.