Molecular sieve issues in pressure swing adsorption for nitrogen production
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Are there any plants that use pressure swing adsorption to produce nitrogen, and what is the consumption of molecular sieves? We have a pressure swing adsorption system equipped with instruments; it produces 300 standard cubic meters per hour at 0.7 MPa, with a purity of 99.9%, and molecular sieves need to be replaced on a monthly basis. But this month is particularly strange – only one tower is missing pieces while the other one is full! ! Has anyone encountered such a situation? What could be the reason, since the valves and seals have been checked and show no problems?
Are you using molecular sieve of the 4A, 5A type, or coke molecular sieve?
The nitrogen production molecular sieve in the adsorption tower is not properly compressed
The poster is probably using dry compressed air to produce nitrogen, right? The two nitrogen production systems on our side are not operating well either; during shutdown for maintenance, the pressure of medium-pressure nitrogen is only 0.7 MPa. Fortunately, there are still a few days before operation resumes, giving us time to carry out the necessary repairs.
Can you afford to top it up every month? 99.9% at 300 M3/H, with carbon molecular sieves in the range of 1250 kg to 1900 kg ； The monthly replenishment amount for these two towers, calculated based on the volume required for proper replenishment, is an absurdly high 20 kg at the very least; the monthly desorption rate of the molecular sieve exceeds 1%, while the annual degradation rate exceeds 12%! Such equipment should be replaced as soon as possible.
It’s really difficult and uncomfortable, right? The amount you mentioned is exactly correct; each time it’s opened, it’s to check whether everything is properly compressed. If the missing material isn’t added in time, the deficiency will become even worse
That’s right – nitrogen is produced using dry instrument air. I was very puzzled by this; upon inspection, it turned out that one of the towers was full while another had less material in it. The compression pistons were in good condition, and the molecular sieves used were identical as well. The cause has been identified: there is a problem with the solenoid valve, as its positioning pins have worn down somewhat. Thank you all for your attention
It was found that the positioning pin of the solenoid valve was worn out; it did not reach the intended position when switched, which led to severe pulverization. The other tower, on the other hand, was in good condition with no defects, as all its solenoid valves were functional. Thank you for following
Coke molecular sieve, carbon molecular sieve 1.5GN-H
Is wear of the solenoid valve positioning pin the cause of pulverization? It is recommended to check again; the cost of replenishing 1.5GN-H on a monthly basis is quite high, around several thousand.