Centrifugal compressor
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What are the reasons for a compressor running in reverse?
The surge valve does not operate in a timely manner; the check valve at the compressor outlet is faulty
When the compressor shuts down, the system does not have enough time to release pressure. If the outlet valve and check valve do not function properly, the backflow valve opening in time can prevent the compressor from reversing; otherwise, the compressor may reverse
Reply to 2# jinglongwo: Thank you. The anti-surge valve of our vehicle is fully open; it seems that the check valve at the outlet, as you mentioned, isn’t working properly. :)
Reply to 3# lizhenpeng: Thank you for your guidance. Even when parking normally, reverse rotation can occur; at that time the anti-surge valve is already fully open, and it is due to this reverse rotation that the dry gas seal gets damaged as well.
Reply to 5# Scatter￥Person: Then you need to check whether the diameter of the return pipeline is smaller than that of the outlet pipe. Most of the gas flows back into the unit, which causes reverse flow. Johnson Controls’ dry gas seals come in single-direction and double-direction types; those of the single-direction type are very sensitive to reverse flow, as it can damage the stationary and rotating rings, and in severe cases, they may not be repairable. Double-direction seals aren’t affected by this issue. Both types have their advantages
Reply to 6# lizhenpeng: There are three return lines, so the problem you mentioned should not occur. However, the outlet pipeline is a bit long, and the check valve is installed at a relatively far distance. For dry gas seals, the ones with single-direction spiral grooves used to get damaged due to reversal, so they were later replaced with those of the double-direction T-type.
The volume formed between the compressor exhaust port, the check valve, and the vent valve has specific requirements, with different manufacturers having varying specifications; an excessive volume in this area can lead to the compressor reversing direction during an emergency shutdown
Reply to 7# Scattered￥ People: Consult the manufacturer; there might be a problem with the design. The check valve is too far away from the compressor outlet, and even if both the anti-surge device and the check valve are functioning properly, the large volume of gas between the compressor outlet and the check valve could cause the compressor to reverse direction. It seems that your dry gas seal groove is unidirectional