Experimental determination of the loss of krypton and xenon in an adsorption purification unit of a contemporary ASU

Abstract

Results are provided for a study in a laboratory test unit of the adsorption dynamics for krypton, xenon, ethane and nitrogen hemioxide (lower oxide) from air in two-layer equipment simulating an industrial adsorber of a combined purification unit (CPU) of a contemporary air separation unit (ASU). As a result of the studies, it is established that the loss of krypton in a CPU is insignificant (about 0.25%) and it is mainly determined by the presence of this component in the gas phase (air) at the end of the purification stage before the start of switching over adsorbers. The loss of xenon is more marked and it depends on the ratio of the calculated adsorber operating time (before the start of the breakthrough carbon dioxide) to the actual adsorber operating time in the purification stage. According to experimental data, the maximum loss of xenon is about 8%. The data obtained point to a marked reduction in the loss of gases in a CPU compared with regenerators used in old ASU schemes within which the losses were about 10-11% for krypton and 25-30% for xenon. It has been established by experiment that during operation of adsorbers of an industrial CPU about 18% of nitrogen hemioxide and 10% ethane is retained within them, but methane is hardly retained. The data obtained may be used in designing units for primary enrichment of krypton and xenon in an ASU.In the industrial production of heavy rare gases, i.e., krypton and xenon, atmospheric air is processed in air separation units (ASU), as a result of which either a primary krypton concentrate (PKC), or so-called dirty oxygen enriched in these air components is obtained.In order to extract rare gases with the use of an ASU, the firm Khrom has created special units for processing both PKC (if the ASU is equipped with a krypton concentration unit), and also dirty oxygen (if there is no unit for primary concentration in the ASU) [1,2].An important problem in the technology for preparing heavy rare gases is achievement of total extraction of krypton and xenon in the first stage of preparing PKC or dirty oxygen, for which it is necessary to estimate possible losses of krypton and xenon in the main ASU assemblies.

Experimental determination of tetrafluoromethane and hexafluoroethane accumulation in khrom-3 krypton–xenon mixture producing equipment

“…The experimental data on Kr and Xe adsorption in the CPU adsorbers for the AFP are cited in [8]. The calculated extraction coefficient values for these constituents, which we obtained on the basis of the experimental data in [8], are adduced in Table 2.…”

“…The calculated extraction coefficient values for these constituents, which we obtained on the basis of the experimental data in [8], are adduced in Table 2.…”