Universal Research Cryogenic Unit for Xenon Production

Abstract

Xenon is a cryogenic product that is currently in short supply. Requirements for its purity are increasing. Its consumption in microelectronics, medicine, and space technology and for high-energy particle physics research is rising. The permissible impurity contents in Xe for various applications were analyzed. A universal research cryogenic unit for Xe production of throughput up to 10 Nm³/h of feedstock mixture was designed. A scheme with separation by rectification and preliminary catalytic and adsorptive purification of the feedstock was chosen. The unit was built in blocks so that processing schemes for Xe production from various mixtures, e.g., Kr–Xe, Xe–N₂, Xe–O₂, could be studied. Trace impurities in Xe were analyzed by gas chromatographs with thermal conductivity (TCD), He-ionization (HID), and flame-ionization detectors (FID). Water vapor in the analyzed gases was measured using laseroptical and coulometric hygrometers. The first runs showed that the unit could produce Xe of purity up to 99.9999 %. Experimental data for rectification of Xe to a purity of 99.999 % are presented. Xe could be purified experimentally from traces of CF₄, C₂F₆, SF₆, hydrocarbons, CO₂, and H₂ to 0.05; O₂ and N₂, 0.1; Kr, 0.01; and water vapor, 0.2 ppm.