Patent ID: 8191386
Filing Date: 2012-06-05
Classification: F25J

Abstract:
1. A distillation method comprising: forming a first compressed stream and a second compressed stream from a compressed feed stream containing components to be separated; discharging the first compressed stream from a main heat exchanger such that the first compressed stream is fully cooled and is substantially condensed; discharging the second compressed stream from a main heat exchanger such that the second compressed stream is partially cooled; expanding at least part of the second compressed stream in a turboexpander to produce an exhaust stream, the second compressed stream being partially cooled such that the exhaust stream is superheated; combining at least part of the exhaust stream with at least part of the first compressed stream after the first compressed stream has been fully cooled and substantially condensed such that a combined stream is produced having a temperature that is no greater than about 10° C. of a saturation temperature of the exhaust stream; introducing the combined stream into a cryogenic distillation process configured to separate the components in the compressed feed stream and to produce at least one product stream enriched in one of the components of a feed stream; and fully warming the at least one product stream within the main heat exchanger; the components of the feed stream comprise oxygen and nitrogen; the distillation process is conducted, at least in part, in a double column unit having a higher pressure column in a heat transfer relationship with a lower pressure column such that a nitrogen-rich column overhead of the higher pressure column is condensed against boiling an oxygen-rich liquid of the lower pressure column; the higher pressure column and the lower pressure column being connected such that a stream of a crude-liquid oxygen column bottoms of the higher pressure column is expanded and introduced into the lower pressure column, streams of nitrogen-rich liquid produced from the condensation of the nitrogen-rich column overhead, at least in part, reflux both the higher pressure column and the lower pressure column; the at least one product stream comprises an oxygen product stream composed of the oxygen-rich liquid column bottoms and a nitrogen product stream composed of nitrogen-rich vapor produced as column overhead in the lower pressure column; the combined stream is introduced into the higher pressure column; the first compressed stream is divided into a first portion and a second portion; the first portion of the first compressed stream is combined with the exhaust stream; and the second portion of the first compressed stream is introduced into at least one of the higher pressure column or the lower pressure column.