Preferably oxygen is displaced by a co current flow of cold nitrogen, following which krypton and xenon are collected by thermal regeneration and {HEAD ~ counter current purging} with {TAIL ~ hot nitrogen} 20, thus avoiding potentially explosive concentrations of hydrocarbons and oxygen in the desorbed gas 22 
with
Preferably oxygen is displaced by a co current flow of cold nitrogen , following which krypton and xenon are collected by thermal regeneration and { HEAD ~ counter current purging } with { TAIL ~ hot nitrogen } 20 , thus avoiding potentially explosive concentrations of hydrocarbons and oxygen in the desorbed gas 22
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH