Failure of the centrifugal compressor. The outlet flow pressure decreases at the fourth and fifth stages.
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I have a centrifugal compressor installed, and recently the flow rates and pressures at the fourth and fifth stages of discharge have suddenly decreased, while the suction pressure has increased. The size of the turbine speed control valve has decreased significantly, from 60% to 45%. It is preliminarily judged that there may be blockages in the first three sections. But there is no concrete evidence. I would like to ask fellow sailors if anyone has any good suggestions?
It’s probably due to the backflow of gas inside the compressor, causing inter-stage leakage
In such cases, it is recommended to disassemble and check the impeller; it may be clogged or damaged. Whether there is a blockage or damage, it needs to be inspected by opening it.
This situation is intermittent; the flow rate increases, and the outlet pressure at stages 4 and 5 rises. But after some time, the flow and pressure at stages four and five decreased slowly again.
Could it be that the inter-stage exit heat exchanger is blocked?
The difficulty now is that this phenomenon is periodic. If it’s about blockage or backflow of air, then it should be continuous.
Is there a pattern to the cycles, or do they occur occasionally?
A pattern can generally be observed: suddenly, the outlet pressure and flow rate increase, then they gradually decline, before increasing again suddenly.
The problem for this sea friend is that this phenomenon is periodic rather than continuous, and that’s where the difficulty lies.