5L-10L oxygen concentrator psa system modification

I have designed a medical oxygen concentrator that has a pressure swing adsorption (PSA) system for 5L/min,10L/min, and 20L/min capacity. The system works, but there are errors in the PSA system design of the system that I designed. I could not make the column pressure balance, PSA loop structure, cycle time software, and orifice design at an optimal level in my system. because of these reasons, I cannot permanently get 95.6% pure oxygen output in the system. (The system reaches 93.3% purity up to 3 liters, but drops to a value between 75-85% above 5 liters.)

My wish is to optimize the PSA system of the oxygen concentrator that I designed and obtain 95.6% pure oxygen permanently over 5 liters.