Patent ID: 8443625
Filing Date: 2013-05-21
Classification: F25J

Abstract:
1. A method of separating air comprising: compressing, purifying and cooling the air; the air being cooled such that a superheated air stream is formed from part of the air having a temperature at least about 5 K above a dew point temperature of the air at a pressure of the superheated air stream; introducing the air into an air separation unit comprising a higher pressure column and a lower pressure column, separating the air into component fractions enriched in at least oxygen and nitrogen within the air separation unit and utilizing streams of the component fractions to assist in the cooling of the air; introducing at least part of the superheated air stream into a mass transfer contacting zone located in a bottom portion of the higher pressure column or in an auxiliary column connected to the bottom portion of the higher pressure column and washing krypton and xenon from the at least part of the superheated air stream within the mass transfer contacting zone such that a bottoms liquid rich in krypton and xenon is produced, the mass transfer contacting zone being operated with a liquid to vapor ratio is between about 0.04 and about 0.15; introducing a stream of the bottoms liquid rich in krypton and xenon into the top of a stripping column and stripping the stream of the bottoms liquid with a stripping gas generated by reboiling the stripping column with a reboiler located in the bottom of the stripping column, thereby producing a krypton-xenon-rich bottoms liquid having a higher concentration of krypton and xenon than the liquid rich in krypton and xenon produced in the mass transfer contacting zone; and withdrawing a krypton-xenon-rich stream composed of the krypton-xenon-rich bottoms liquid from the stripping column.