Process for producing krypton and xenon

A process for producing krypton and xenon, comprising the steps of:

• supplying to a first concentrating column liquid oxygen containing small concentrations of krypton, xenon, and hydrocarbons including methane accumulated in a main condensation section of an air separation plant;
• rectifying and concentrating said liquid oxygen in the first concentrating column in which concentrations of said Kr,Xe and hydrocarbons are increased;
• introducing the concentrated liquid into a methane purging column;
• maintaining operation conditions within the purging column below explosive limits solely by bringing said concentrated liquid into countercurrent contact with oxygen gas introduced into the purging column in the absence of extraneous argon gas, and purging the methane with the oxygen from the top of the purging column;
• bringing out of the methane purging column and vaporizing the concentrated liquid remaining in the bottom of the purging column;
• thereafter effecting combustion of the vaporized concentrated liquid in a catalytic combustion reactor;
• absorbing and removing water and carbon dioxide produced from the combustion for producing a purified gas mixture;
• and
• separating a mixture of krypton and xenon from the purified gas mixture in a second concentrating column.