Do centrifugal compressors also surge under high load conditions?
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Do centrifugal compressors also surge under high load conditions? When we first started driving the centrifugal compressor here, we tried to open the large return line but found that there was a tendency to surge. At that time, the technician said that our curve was wrong, but now he says that it is indeed possible. Can you explain it?
Haha, when the centrifugal compressor is under high load, if the speed of the centrifuge driver cannot keep up or drops, it may cause surge. I personally think that the diameter of the outlet pipe is certain, that is, the area is certain. The high load of the centrifuge means that the flow rate increases. Of course, the weight of the gas also affects the load of the compressor. Generally speaking, the gas will be heavier at night and lighter at noon. When the flow rate increases, if the air flow velocity does not increase, the gas on the same cross-section of the pipe will increase than before, causing the outlet to be pressurized. Affects surge. If the flow rate increases and the inlet butterfly valve is not opened, the inlet flow rate is not enough, which may also cause the turbine or motor to be overloaded.
Centrifugal compressors will surge under any load.
Surge, also known as surge, is a phenomenon unique to centrifugal compressors. I think this question is not difficult to answer. Just look at the surge diagram of the compressor to understand!
The centrifuge will surge, and the refrigerator in our factory often surges.
The surge curve is a graph showing the relationship between flow and pressure ratio, and has little to do with load.
Generally, centrifugal compressors will give users a theoretical surge curve when they leave the factory. The actual surge line can only be obtained through experiments. Sometimes the deviation is very large. The anti-surge control system is based on the surge curve. A certain speed (load) corresponds to a certain surge line. The situation you mentioned It is very likely that your anti-surge control system is based on the theoretical curve, so you see that the surge flow rate is low at low speeds. In fact, at low speeds, the anti-surge valve is generally fully open. If the flow rate is very low, it is wrong. Generally speaking, the same is true at high speeds. You can ask your technician if your anti-surge control system is based on the theoretical curve to find out.
Whether a centrifugal compressor surges is determined by the outlet pressure head and flow rate.
I feel that increasing the load alone should not cause surge. Our unit is rated at 276,000. Due to process requirements, I mentioned the 300,000. It seems that the surge line has not changed. I would like to ask experts for advice.
When the compressor speed remains unchanged and the outlet flow rate is increased without much change in pressure, the only option is to stay away from the surge line.； If it is a steam turbine, the surge line corresponding to the compressor speed at this time should be