Cryogenic production of krypton and xenon from air

In a process for the production of krypton and xenon from a liquid feed stream comprising oxygen, methane, krypton and xenon in a single krypton/xenon cryogenic distillation column, wherein the liquid feed stream is introduced to the bottom of the single distillation column for fractionation into an bottoms liquid enriched in krypton and xenon and an overhead lean in krypton and xenon and the single distillation column has a region wherein oxygen is enriched, the improvement for simultaneously maximizing the concentration of krypton and xenon and the rejection of methane comprises operating said region wherein oxygen is enriched so that ratio of liquid to vapor flow is in the range between 0.05 and 0.2.

In a process for the production of krypton and xenon from a liquid feed stream comprising oxygen, methane, krypton and xenon in a krypton/xenon cryogenic distillation system comprising a first and a second distillation column, wherein a first portion of the liquid feed stream is introduced into the top of the first distillation column for fractionation into a first bottoms liquid and a first overhead, wherein a second portion of the liquid feed stream is introduced into the top of the second distillation column for fractionation into a second bottoms and a second overhead, wherein a vapor stream is withdrawn from an intermediate location of the first distillation column and fed to the bottom of the second distillation column and wherein the second bottoms liquid is withdrawn and fed to the intermediate location of the first distillation column, the improvement for simultaneously maximizing the concentration of krypton and xenon and the rejection of methane comprises operating said second distillation column so that ratio of liquid to vapor flow is in the range between 0.05 and 0.2.

In a process for the production of krypton and xenon from a liquid feed stream comprising oxygen, methane, krypton and xenon in a krypton/xenon cryogenic distillation system comprising a first and a second distillation column, wherein the liquid feed stream is introduced into the top of the first distillation column for fractionation into a first bottoms liquid and a first overhead, wherein a vapor stream is withdrawn from an intermediate location of the first distillation column and fed to the bottom of the second distillation column for rectification, wherein the second bottoms liquid is withdrawn and fed to the intermediate location of the first distillation column and wherein reflux is provided to the second distillation column by condensing at least a portion of the second column overhead and returning said condensed overhead portion to the top of the second distillation column, the improvement for simultaneously maximizing the concentration of krypton and xenon and the rejection of methane comprises operating said second distillation column so that ratio of liquid to vapor flow is in the range between 0.05 and 0.2.