Brief description of the molecular sieve problem
The purifier CO₂ suddenly started to run abnormally and suddenly went out of range in liquid air separation plants, the dew point never changed significantly.
The dew point did not change significantly. In order to ensure that the other molecular sieve had enough time to regenerate, the time could not be shortened any further. At this point there was a relatively stable situation with no further deterioration. Check the trend graph for a cold blow peak of 135 degrees. Same as before. There was no reduction in the regenerated gas volume either. After the problem appeared, the process staff discussed and analysed together the possible causes.
1 The analysis table had drift and there was a leak in the analysis tube. There was nothing unusual about the analysis table with the standard gas calibration team. Using foam water to check for leaks, no leaks were found either. And the purifier was running CO₂ normally. This also means that there is no problem with the analysis table.
The purifier was analysed for water in the molecular sieve and the inlet temperature trend was carefully checked. There was no sign of water in the curves such as cold blow peak.
The steam heater was analysed for leaks and the trace water analyser was connected to the steam heater outlet and no significant change was found. And the other purifier could be operated normally.
The purifier was analysed for unevenness, uneven bed convexity and unevenness, caused by bias flow of gas volume. On closer analysis, this is not very likely, but if it is a bias flow, the phenomenon should be CO₂, which is getting worse and worse, which means that the switching time is getting shorter and shorter. Therefore, this is not very likely either.
The analysis shows that there is a leak in the alumina or molecular sieve of the purifier and that the screen is broken. At first the leakage is small, but later it increases, because the space under the molecular sieve adsorber is limited. The leakage reaches a certain level and a self-sealing phenomenon is formed. This is more in line with the exceedance of the standard at the site.
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