There is a problem with the dry gas seal in my hydrogen compressor; since it started operating again after maintenance, nitrogen is present in the hydrogen output.
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I have installed a hydrogen compressor; the dry gas seal type used is one that features intermediate labyrinth-type dry gas seals in series. The primary sealing gas enters the compressor after being filtered from the hydrogen gas at the compressor outlet, while both the secondary sealing gas and the isolation gas are supplied with nitrogen. Under normal circumstances, nitrogen shouldn’t enter the compressor, right? What could be the reason? Please ask the fellow sailors for help.
The sealing surface might be fine; could there be leakage at the area where the auxiliary seal ring is located?
So, this friend, it means that the auxiliary seal ring of the primary seal is damaged, allowing low-temperature nitrogen from the intermediate labyrinth to enter the primary seal chamber through the damaged auxiliary seal ring, and thus into the machine body?
In other words, can the pressure of the secondary sealed nitrogen gas coming out of the middle labyrinth penetrate through the auxiliary sealing ring? Rather than with primary sealing, more hydrogen gas passes through the auxiliary seal ring.
How can one tell if nitrogen has leaked into the hydrogen outlet?
We detected the presence of nitrogen in the hydrogen at the compressor outlet.
The sealing gap of the dry gas seal is above the specified limit, and there are issues with the installation. By monitoring the flow rate of the sealing gas, if it is only slightly above the normal value, the seal can still be used, but close monitoring is necessary. If the excess is significant, it is recommended to shut down the equipment for maintenance or gently tap the seal to prevent poor sealing caused by the presence of fine impurities
The problem now is that the gas used for the primary seal is hydrogen, which is the process medium. If the primary seal leaks, then both the gas used for the primary seal and the process medium will leak into the flare line. As a result, the amount of gas leaking from the primary seal should increase, or it might penetrate the labyrinth seal between the primary seal chamber and the secondary seal chamber, entering the secondary seal chamber and thereby causing an increase in leakage from the secondary seal and an increase in secondary emissions. But the question is: how does the nitrogen gas used for the secondary seal get into the compressor?
Could it be that there is a leak in the nitrogen filling valve of the system?
Blind plates are always installed on the machine’s nitrogen flushing valves after maintenance – it’s part of the procedure.
This requires different treatment; our compressor system has high-pressure nitrogen and low-pressure nitrogen, and only high-pressure nitrogen is equipped with a blind flange!