What are the causes of surge in centrifugal compressors, and how to adjust them?
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What are the causes of surge in centrifugal compressors, and how can it be adjusted?
Compressor inlet flow rate, outlet pressure, molecular weight of the compressed gas. The outlet pressure should not be too high; it is necessary to maintain the inlet flow rate and increase the molecular weight of the medium to keep it close to the design value
Excessively high suction temperature; reduced suction pressure; decreased rotational speed; lower molecular weight; changes in pipeline pressure, such as closing the exhaust pipeline valves, can all cause surge in centrifugal compressors
As a supplementary note, for compressors driven by back-pressure turbines, a decrease in the turbine’s inlet pressure and an increase in its exhaust pressure can also cause surging; this issue can be alleviated by reducing the exhaust pressure. In my current practice, I adjust the situation by maintaining a stable inlet flow rate and reducing the pressure on the downstream side; of course, it is also possible to vent gas at the outlet
It is mainly caused by a mismatch between flow rate and pressure and the unit; the current solution adopted is to vent.
Simply put, it is surge caused by low inlet flow and pressure, as well as high outlet pressure due to blockage. The solution is to open a vent to reduce the pressure at the compressor outlet, thereby bringing the anti-surge point back to its normal level. Alternatively, the compressor circuit can be activated to return the outlet flow and pressure to the inlet, thereby maintaining the inlet flow and reducing the outlet pressure; at the same time, the load on the unit will decrease accordingly.
The main reasons are low inlet flow and high outlet pressure; common solutions are to enable backflow or reduce the outlet pressure
A low flow rate at the compressor inlet can cause surge