Sequence of closing the anti-surge valve of the propylene compressor
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The propylene refrigeration compressor features a 6-stage, 3-section design; three anti-surge lines are installed at the compressor outlet, namely Three Circuit 1, Three Circuit 2, and Three Circuit 3. I would like to know the sequence in which these three anti-surge valves close once the rated speed is reached. Experts, please help!
At this time, it cannot be simply determined by the shutdown sequence; it must be decided based on the anti-stall margin! Close the one whose load is increasing gradually first. Theoretically, it’s the coolant at higher temperature that should be used first, so the high-temperature section should be closed first! From the perspective of preventing surge, it is also necessary to close the high-pressure section first before closing the low-pressure section!
First, it should be reduced to three turns at three, then gradually to three turns at two, and finally to three turns at one. Of course, when making these reductions, the anti-surge line must be taken into account.
The 3rd floor is the correct option; you need to understand that only by first closing 3 and sending material back to 3 can the material be transported forward. After that, it’s 3 back to 2, then 3 back to 1. If the order is reversed, the compressor’s first stage will keep sucking in air while the third stage continues to send material forward, which will definitely lead to pressure buildup and surge
First, turn off the one with lower pressure, that is, the third circuit, and so on; otherwise, if the third circuit is turned off first, the inlet pressure will remain unchanged while the outlet pressure will rise and the flow rate will decrease, which can lead to surge. Personal opinion.