Factors affecting the purity degradation of PSA oxygen generation
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Dear seniors: In the practice of PSA oxygen production, the purity of the oxygen generators remains above 93% during the first few years, but it decreases after 3 years. I’ve seen oxygen generators abroad that have been in use for 8 years, and their purity remains the same as before. It’s mainly related to those factors. Seeking guidance?
Maybe the molecular sieve is no longer functional; replace it with a new one
In pressure swing adsorption, purity and yield are inversely proportional within a certain range. After operating for a long time, due to the strength and wear of the molecular sieve, as well as the influence of moisture in the air, it may become powdered and lose its effectiveness. To maintain the original yield, the alcohol concentration is sacrificed; to maintain the concentration, the yield is sacrificed.
Molecular sieves were the first thing that came to mind, but the results after adding them were still not very satisfactory. Our adsorption pressure is 4.5 kilograms. I see that abroad they all reach 7 kilograms. Isn’t this also a reason?
The principle of pressure swing adsorption is adsorption under pressure and desorption under reduced pressure. Theoretically, the higher the adsorption pressure, the lower the desorption pressure should be, which is better. However, in practice many factors need to be considered, such as energy consumption and equipment selection. There is an optimal point. You should get in touch with the molecular sieve manufacturers, or we can talk about it as well.
As far as I know, the adsorption pressure for industrial oxygen production using PSA is generally around 7–8 kg, while that for small household oxygen generators is 2–4 kg. I’ve never seen one that weighs 4.5 kg. Additionally, the pretreatment of raw air, such as dehydration and degreasing, is very important. Failing to do this step properly will affect the lifespan of the molecular sieve
Could the original poster describe in detail the entire addition process? Also: 1. What type of molecular sieve was added? ； 2. The ratio of the added amount to the original amount.
It’s also possible that problems arise after the valve has been in use for a long time
Yes, factors such as molecular sieves, packing techniques, operating pressure, and valves that have been in use for a long time or are leaking can all affect production volume and oxygen concentration. In China, the operating pressure of PSA oxygen generators is generally between 5 and 8 kg; those with a pressure below 5 kg are rare and cannot fully utilize the oxygen-generation capabilities of the molecular sieves.
An unreasonable design of the water removal layer at the air intake side can also have an impact!
Why is the pressure level so high for you? Here, the maximum adsorption pressure for VPSA is 36 KPa, and the vacuum level can reach -67 KPa.