PSA hydrogen production – vacuum pumping, but the vacuum level is not sufficient
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For PSA hydrogen production during vacuuming, if the vacuum level is not satisfactory, what could be the reasons? The vacuum pump seems fine; is there a problem with the adsorbent? Leakage inside the valve? If there is internal leakage in a valve, shouldn’t multiple valves have internal leakage as well? :):):):)
If there is suspicion of internal leakage in the valve, checking the pressure trend will reveal whether it is indeed caused by internal leakage; for any suspected issue, simply investigate each possibility one by one.
1. First, clarify the following factors: confirm that the vacuum pump reflux is turned off to rule out internal leakage issues; check whether the operation of all towers follows the operating manual (to rule out the possibility of programming errors); and verify whether the pressure at the start of vacuum pumping was 0.01–0.03 MPaG If it is higher than this pressure, then there is a problem with the pressure reduction mechanism mentioned earlier. 2. View the vacuum pumping curve. If a particular tower cannot be lowered, it is a problem with that specific tower; check the valves of that tower. If none can be extracted, it’s a common issue. 3. If it’s a common issue, is it possible that the adsorption time is too short, resulting in failure to extract it? Can the time be extended? If the time cannot be extended, then check the vacuuming curve; if the curve continues to show a downward trend toward the end of the vacuuming process, it may be a problem with the vacuum pump – for example, an undersized pump, quality issues with the pump itself that prevent adequate vacuum levels from being achieved, or excessively high water temperature in the pump (in the case of water ring pumps). It is possible to diagnose problems with the vacuum pump by checking the pressure gauge at its inlet.