Production of oxygen-lean argon from air.

摘要

The present invention is an improvement to a method of producing crude argon directly from the cold box of a cryogenic air separation unit. The improvement is the production of crude argon containing greatly decreased concentrations of oxygen, i.e. <0.5% oxygen, without any loss in recovery. The improvement is accomplished by using an effective number of theoretical stages in the side arm column (135) so as to produce the desired argon product purity without sacrificing argon recovery; feeding crude liquid oxygen (129) from the bottom of the high pressure column (107) to the reboiler condenser (133) located in the top of the argon side arm column (135) at a rate in the range from about 1.04 to about 1.36 times the theoretical minimum flow of crude liquid oxygen necessary to completely vaporize that minimum flow of crude liquid oxygen to its dew point; and effectuating the intimate contact between the vapor and liquid phases in the argon side arm column (135) by a combination of conventional sieve trays and low pressure drop, structured packings so that the pressure drop across this combination results in a pressure at the top of the argon side arm column (135) such that the flow of crude liquid oxygen to the reboiler/condenser (133) located in the top of the side arm column can be maintained in the appropriate range. Furthermore, the improvement is accomplished without an energy penalty in the cryogenic air separation unit.