Seeking advice on dry gas seal issues with centrifugal compressors
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Dear sea friends, I have a question: we have a CO centrifugal compressor that uses dry gas seals. The normal main seal gas is the CO return from the fifth stage outlet; during startup and shutdown phases, nitrogen is used. There is a crossover with two valves between the isolated nitrogen and the main sealing gas. The PID tag is set to NC, but we keep it enabled in normal operation to prevent nitrogen from automatically filling in as the sealing gas when the compressor stops. However, recently the company conducted a survey to check for backflow issues, and it was found that in our case, even with two check valves in place, it is still possible for CO to mix with N2. We have been instructed to close the cross-line in accordance with the PID requirements ； But I would like to ask that in this case, when the compressor stops suddenly, even if an operator runs over to open this bypass line, it won’t have any impact on the dry gas seal, right – at least not for 5 minutes? Dear sea friends, how do you manage this situation with your devices? How can we prevent backflow? Thank you!
Do you mean to add a pump for the nitrogen?
Thank you. I haven’t seen this process; could you share it?
You can ask the manufacturer; we should be using a pressure pump, and I think I’ve seen information about nitrogen tanks online
Then could you share the process of the booster pump? I’ve never even heard of it before; this is the first time I’m hearing about dry gas seals and pressure boost pumps. It’s tricky, thank you
Media crosstalk is quite severe; isolation is definitely necessary. The booster pumps for the circulators in hydrogenation units are standard equipment
Technical upgrades are indeed needed; adding a pressure pump would be just right.
You can contact the manufacturer to add a pressure booster pump. We use hydrogen circulation compressors, which already come equipped with one; however, this pump is used only when the machine is turned on. Once the system pressure reaches the appropriate level, we can use our process gas for sealing purposes