The air intake volumes of the two molecular sieves are different. What’s going on?
Thread Content
For the air separation unit with model 23500 and an air flow rate of 120,000, the issue with the molecular sieves is that, ever since they have been in use, the amount of air flowing through them has been different for the two molecular sieves. When one of them passes through the air compared to the other, the amount of air is about 4000 units less. The sizes of the two molecular sieves are almost the same, and the amount of molecular sieve used is roughly identical; this has a slight impact on the air flow conditions. What is the reason for this situation? Has any other member of this forum experienced something similar with their flight crew?
Is there a large difference in pressure drop between the two molecular sieves when they are operating normally? Is your compressor pressure-controlled?
This post was last edited by Tianxia Di Ji on 2011-9-18 at 20:34. Such issues should occur in the molecular sieve itself; it’s unlikely that a 1’ leak would result in such a large amount of leakage that it can be detected. Check the actual opening degree of the 2” valve; the fact that the butterfly valve cannot be opened fully has some impact. 3’ One of the molecular sieves has had problems, such as poisoning in the ‘punching machine’. 4’ Key point, pay attention. . The total amount of material filled is fine; the bed layer is level and its height is approximately the same. However, it’s possible that the ratio of activated alumina to molecular sieve differs between the two sets. Over time, as the molecular sieve fills in the gaps left by the alumina, the air volume changes. This is the most likely scenario. I’ve encountered this before: when filling with alumina, I noticed that the amounts placed on each side of the empty tank differed significantly. Upon checking, it turned out that the filling quantity was indeed different. These people are extremely irresponsible; such things can happen at any installation site. I didn’t understand that; let me explain in detail.
1 Is the purifier that’s missing causing high resistance? 2 Check if there is any internal leakage. 3 It’s possible to tell whether the valves are in place or not
Reply to 3# Tianxia Di Ji: “Molecular sieves fill the gaps in alumina, which causes a change in the amount of air.” It’s about this – please explain it, Brother Tianxia! Thanks first!
Internal leakage in the switch valve of the purification system.
First, install the magnetic balls and then lay a layer of mesh as a barrier between them and the molecular sieve, right? The edges of the mesh are raised, so the molecular sieve will definitely leak downward, but not in large amounts. As for whether you believe me or not, I do believe it. That’s not the key point; what matters is that different amounts of magnetic balls in the tank result in different resistances for the two tanks, yet the changes in the resistance meter are not significant. It is possible to determine this using other methods: the pressure release speed – more magnetic balls mean a faster pressure release, and by looking at the curve of the pressure release during molecular sieve regeneration, it can be seen that greater depths of depression correspond to faster pressure release. 2’ Check the opening degree of the air compressor vanes; in pressure-controlled compressors, the opening degree of the vanes also changes due to variations in resistance. I’ve been working on the regulations these past few days, and my mind is a bit confused; I can’t think of everything. I’ll just say what comes to mind – it’s a bit chaotic. If there’s anything you don’t understand, ask again.
This post was last edited by solo14 on 2011-9-19 12:50. I have seen this issue on several sets of equipment. The flow rate of air entering the fractionation tower is automatically controlled by the air compressor vanes, resulting in a constant amount of air entering the tower. When #1 molecular sieve is in operation, the opening degree of the air compressor vanes needs to be increased by 3%; as a result, the pressures in both the upper and lower towers increase, and the adsorption resistance of the molecular sieve also rises. It has a significant impact on the argon content in the argon fraction; the fluctuations during the period of switching between the two molecular sieves are much greater than those during normal pressure equalization phases. The manufacturer came and said that in the 2# molecular sieve, some of the air did not pass through the entire molecular sieve, resulting in a short circuit. I think it’s true that this kind of situation likely exists in many air separation units, and it’s almost certainly a problem with the molecular sieves; after all, it’s still very difficult in China to produce molecular sieves that are perfect in quality.
By combining the answers from the above individuals and examining them, perhaps an answer will emerge~
It seems that the possibility of internal leakage is high; switch valves and check valves are prone to problems.