Medical oxygen on-site
Master thesis developing a medical oxygen purifying system using PSA
J.P.K. Schretlen (TU Delft - Mechanical Engineering)
T. J.H. Vlugt – Mentor (TU Delft - Engineering Thermodynamics)
M. van der Elst – Mentor (TU Delft - Medical Instruments & Bio-Inspired Technology)
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Abstract
When COVID-19 hit the Western world, it exposed an already existing shortage of medical oxygen. This study focuses on designing an oxygen purifier capable of producing high-purity oxygen on-site using Pressure Swing Adsorption (PSA) technology. Although small-scale oxygen devices are available on the market, little public information exists about their dimensions and working conditions. This research fills this gap by making the design open source, providing a foundation for other technicians, particularly in the developing world, to implement on-site oxygen production, which is essential for surgical use. Building upon a previous multi-column project that achieved peak oxygen concentrations of 75%, this study develops and thoroughly tests a single-column system. By varying adsorption and desorption pressures, fluctuating mass flow, and different desorption times, a comprehensive overview of its performance is obtained. These results are integrated into a configuration scheme representing multiple single-column systems giving insights into the amount of columns and pumps necessary to meet a patients demand. Experimental results showed that for lithium-treated zeolite, an adsorption pressure of 2 bar is sufficient, as higher pressures do not significantly improve outlet concentration performance. During desorption, a substantial increase in oxygen concentration was observed when using 0.3 bar instead of 0.5 bar, with peak concentration differences of almost 20%. Desorption time also plays a significant role in both outlet concentration and the overall system configuration. It can be concluded that a single-column system does not meet the requirements to provide the necessary oxygen concentration for a patient. While peak concentrations of 70% were measured, achieving a sustained average of 70% would require higher peak concentrations. Future works should explore alternative setups, particularly those incorporating a recycling system to enhance oxygen concentration peaks.