A simple issue with dry gas seals
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There is a problem related to dry gas seals that has been bothering me: generally, large compressors use series-connected dry gas seals. The primary seal gas uses its own process gas, namely the process gas at the final outlet, to enter the dry gas seal system. So I have a question for the experts: As the exhaust gas passes through components such as pressure drops in pipelines, filters, and control valves to reach the dry gas seal, will its pressure be lower than that of the high-pressure cylinder? How can the gas inside the cylinder be sealed in such a situation? The amount of primary seal gas that leaks into the cylinder is approximately 90% of the amount that enters the dry gas seal. Please, an expert, help to answer.
A small amount of process gas leaked between the sealing surfaces and was burned in the flare along with the secondary buffer gas.
Judging from the arrows on the diagram, the flow direction of the gas can be determined: most of the process gas enters the compressor through a labyrinth to prevent dirty process gas from entering the sealed chamber, while a small amount of the process gas leaks through the annular gap and mixes with the secondary buffer gas before being discharged to the flare
We use high-pressure nitrogen, with a pressure higher than that of the process gas. If the primary seal gas is the outlet process gas, I have the same question as the original poster; I’m waiting for an expert to provide an answer.
The pressure of the primary process gas must be higher than the pressure inside, and it is necessary to ensure that the flow velocity through the seal is not less than 5 m/s. Otherwise, it is easy to cause unclean process gas to backflow
We are all aware of this trend; the question is whether the main sealing gas can still enter the cylinder with relatively high pressure after passing through the comb-tooth seal In fact, that’s exactly how he left. I know that, but I just want to ask what really happened?
Those with balance tubes on the high-pressure side of the compressor
The primary seal gas is controlled based on the pressure difference with that of the high-pressure cylinder; obviously the pressure is higher, but it’s quite amazing that it can still enter the cylinder after passing through the comb teeth: lol
Don’t worry about this; it’s definitely possible to get in. For a first-class sealed system, there are requirements regarding flow rate and pressure – if these conditions aren’t met, sealing issues will arise