Principle of the controlled process for washing molecular sieves with liquid nitrogen
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Dear all**, what are the sequence controls for cleaning molecular sieves with liquid nitrogen, and according to which process considerations are these controls programmed? Or, what process requirements must each step of the sequential control meet? To be more specific: to what pressure is the pressure released after high-pressure isolation of the molecular sieve? Why is it that the condition for complete pressure relief is also that the pressure difference before and after the low-pressure nitrogen inlet valve is not high? Why is that?
This is probably to take safety into account. The main purpose is to prevent high voltage from leaking into low voltage. Whether the pressure relief of the molecular sieve has been completed is determined by the pressure value read from the pressure gauge. If the pressure gauge is faulty, for example, when the actual pressure is 10 bar but the gauge reads 0.5 bar, then opening the low-pressure nitrogen valve will result in cross-pressurization. So, an additional constraint is usually added, which is what the original poster mentioned: it is necessary to check whether the pressure difference across the low-pressure nitrogen inlet valve is too large; if it is, the low-pressure nitrogen valve shall not be opened.