Extraction of krypton or xenon-enriched mixture

摘要

The extraction system is integrated into an air separation plant with a double column (1) having a high-pressure section (2) and a low-pressure section (3). A krypton/xenon-rich fraction is taken from the low-pressure column at (16) and passed into a material exchange column (15). The major portion enters the column near its middle at (25) whilst a minor portion enters the head at (26). The other component of the fraction is oxygen. In an alternative method the fraction is injected in its entirety at (25) whilst almost pure oxygen is injected in the head. Nitrogen (18), as the inert gas, is passed into the base of the column at (19). The krypton/xenon rich mixture then collects at the base of the column and is withdrawn at (23). In the above description all gases are liquefied except that, at the base, an evaporator (21) vaporizes the product, gaseous nitrogen being used as the heat exchange medium.