Patent ID: 8820115
Filing Date: 2014-09-02
Classification: F25J

Abstract:
1. A method of producing an oxygen product comprising: separating air by a cryogenic rectification process employing a plurality of air separation units having higher pressure columns and lower pressure columns operatively associated with the higher pressure columns to produce oxygen-rich streams that are utilized in producing the oxygen product, the cryogenic rectification process generating at least one liquid stream composed of air or an air-like substance having an argon content no less than air and at least one impure oxygen stream containing oxygen and nitrogen and having an oxygen content no less than that of the air; introducing the at least one impure oxygen stream into a bottom region of an auxiliary column operating at substantially the same pressure as the lower pressure column and rectifying the at least one impure oxygen stream in a rectification conducted within the auxiliary column to form an oxygen containing liquid as a column bottoms and an auxiliary column nitrogen-rich vapor column overhead; withdrawing oxygen containing streams from the auxiliary column having a lower nitrogen content than that of the at least one impure oxygen stream and introducing the oxygen containing streams into the lower pressure columns for rectification within the lower pressure columns; introducing intermediate reflux streams composed of the at least one liquid stream into the lower pressure columns above locations at which the oxygen containing streams are introduced and into the auxiliary column above the bottom region thereof and the at least one impure oxygen stream and rectifying the intermediate reflux streams within the lower pressure columns and the auxiliary column; and the at least one impure oxygen stream valve expanded to initiate formation of an ascending vapor phase within the auxiliary column for the rectification conducted within the auxiliary column and the ascending vapor phase produced solely as a result of the introduction of the at least one impure oxygen stream and one of the intermediate reflux streams into the auxiliary column.