Patent ID: 8286446

Claim:
A method of producing an oxygen product from a feed stream comprising oxygen and nitrogen, said method comprising: partially condensing a first part of the feed stream and condensing a stream made up, at least in part, of a second part of the feed stream after the first part of the feed stream has been compressed, the second part of the feed stream has been compressed to a higher pressure than that of the first part of the feed stream and the first part of the feed stream and the second part of the feed stream are cooled within a main heat exchange zone; introducing said first part of the feed stream into a higher pressure column of a distillation column system; rectifying liquid resulting from the condensation of the stream made up, at least in part of the second feed stream in the higher pressure column and a lower pressure column of the distillation column system; partially vaporizing a first crude liquid oxygen stream primarily comprised of crude liquid oxygen column bottoms produced in the higher pressure column through indirect heat exchange with a nitrogen-rich stream composed of nitrogen-rich column overhead produced in the higher pressure column, thereby producing a liquid nitrogen containing stream utilized as reflux to the higher pressure column and the lower pressure column; disengaging liquid and vapor phases from the first crude liquid oxygen stream after having been partially vaporized to form a crude oxygen vapor stream and a second crude liquid oxygen stream; passing an oxygen containing stream made up at least in part of the second crude liquid oxygen stream in indirect heat exchange with the first part of the feed stream, thereby to effect the partial condensation of the first part of the feed stream and to at least partially vaporize the oxygen containing stream; introducing the crude oxygen vapor stream, as a vapor and the oxygen containing stream, after having been at least partially vaporized, into successively lower points in the lower pressure column and such that oxygen containing stream is introduced below the crude oxygen vapor stream; producing boil-up within a bottom portion of the lower pressure column by at least partially vaporizing an oxygen-rich liquid column bottoms produced within the lower pressure column by indirect heat exchange with the stream made up at least in part from second part of the feed stream, thereby effectuating the substantial condensation thereof; and forming an oxygen product stream from either residual liquid or vapor produced from the at least partial vaporization of the oxygen-rich liquid column bottoms.