Why does the new hydrogen compressor still require a separate nitrogen startup valve?
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The molecular weights vary under different operating conditions; the reason compatibility is possible is that the molecular weights in those other conditions are similar, which allows for compatible use. Is the difference in molecular weight too large for nitrogen? What problems might arise if valves designed for other hydrogen operating conditions are forced to be used?
The vessel needs to be purged with nitrogen for maintenance purposes, and the system also requires nitrogen purging and airtightness
Since the molecular weight of the medium needs to be taken into account when designing the gas valve (issues such as springs), a separate nitrogen startup valve is provided. In my opinion, it’s mainly to avoid damaging the official valves; startup valves are cheaper. We just used the standard valves for the testing, and there were no issues.
What the poster is referring to is probably the valve used for nitrogen testing of the compressor, right?
If it is a test air valve, please refer to the answer on the third floor.
Nitrogen molecules have a higher molecular weight, so their compressibility is lower compared to hydrogen. When using a hydrogen valve to handle nitrogen, the outlet pressure should not be too high, and attention should be paid to the exhaust temperature.
The nitrogen valve is primarily used to ensure the airtightness of nitrogen in the reaction system and for thermal testing. Hydrogen valves can be used to transport nitrogen, but only for a short period of time, usually a few hours or days; prolonged use will reduce the valve’s lifespan or even cause it to get damaged. All valve manufacturers do not recommend using hydrogen valves for nitrogen. Generally, when new plants purchase units, they also acquire a set of nitrogen valves for use during the first startup, or after the catalyst in the plant is replaced. After starting up, switch to the regular hydrogen gas valve.