Impact of highly concentrated contaminants on the quality of oxygen 93 % produced by pressure swing adsorption.

Abstract

A zeolite based pressure swing adsorption (PSA) module designed to produce medicinal oxygen with 90 - 96 % oxygen content was exposed to high input concentrations and high total amounts of CO (17.7 %, 44 mol), CO2 (16.5 %, 23 mol), NO2 (0.98 %, 2 mol), NO (6.2 %, 6 mol) and SO2 (4.2 %, 6 mol). In addition the system was operated with up to 35 % argon in the feed gas. An empirical model was developed to describe the dependence of the oxygen concentration in the product on the oxygen concentration in the input. If the oxygen concentration in the feed gas was reduced below 18 % by dilution, the oxygen concentration in the product fell under the 90 % threshold. Additional effects were observed with NO, NO2 and SO2 which are apparently due to chemical reactions on the adsorbent. These effects consisted of a further decrease in the oxygen concentration measured in the product and could not be reversed by excessive regeneration of the module with air. Under the experimental conditions used, only CO was detected in the product. Appropriate CO monitoring of the input gas is considered a possible remedy for PSA modules in order to ascertain the pharmaceutical quality of the oxygen produced.