Patent ID: 6253576
Filing Date: 2001-07-03
Classification: F25J

Abstract:
A process for separating air to produce oxygen at an intermediate pressure, said process using a higher pressure column and a lower pressure column in thermal communication with the higher pressure column through a main reboiler-condenser, wherein each column has a top and a bottom, and wherein the main reboiler-condenser provides at least a fraction of boilup at the bottom of the lower pressure column, comprising the steps of:providing a first stream of compressed air;dividing the first stream of compressed air into a first portion of air and a second portion of air;feeding the first portion of air to the higher pressure column at a first pressure;withdrawing a stream of liquid oxygen from the lower pressure column; andheat exchanging the stream of liquid oxygen with the second portion of air, said second portion of air being at a second pressure lower than the first pressure, thereby at least partially condensing the second portion of air and at least partially vaporizing the stream of liquid oxygen.