The optimal design of pressure swing adsorption process of air oxygen enrichment under uncertainty

The paper formulates and studies the problem of optimal (by the criterion of profits from oxygen production) design of a pressure swing adsorption (PSA) unit for air oxygen enrichment under partial uncertainty of the source data (the air composition, temperature, atmospheric pressure) with limitations on oxygen purity, unit capacity, and resource saving granular adsorbent. A heuristic iterative algorithm was developed for solving an optimal design problem under partial uncertainty of the source data. An auxiliary optimization problem related to the class of nonlinear programming problems (assuming the approximation of continuous control functions at the stages of the adsorption-desorption cycle by step-functions) was formulated and then solved by the sequential quadratic programming method. The problem of optimal design was solved for the range of PSA units with a capacity of 1 to 4 l/min allowing to obtain oxygen with a purity of 40 to 90% vol. According to the findings, we analyze the most promising operational and design parameters ensuring the maximum profit in the operation of the PSA unit, taking into account the saving of the granular adsorbent. It was established that the introduction of limitations on the gas flow rate in the frontal layer of the PSA unit adsorbent allows to increase the reliability of its operation and the adsorbent service life.