Cryogenic gas separation with liquid exchanging columns

Claim 2

A subambient multi-component gas distillation process, comprising: rectifying said multi-component gas to provide a substantially pure first component overhead liquid and a liquid bottom mixture enriched in a second component and a source of reboil; providing a first and second low pressure column; providing reboil to said first and second low pressure columns from said source; feeding said liquid bottom mixture to said first LP columns; feeding the bottom liquid from said first column to said second column; providing reflux to said second LP column by indirect heat exchange with at least part of said substantially pure first component overhead liquid; feeding the overhead from said second LP column to said first LP column; withdrawing a substantially pure gaseous first component from the overhead of said LP column; withdrawing a substantially pure fluid second component from the bottom of said second LP column.

Claim 3

The process according to claim 1 further comprising supplying cooled and cleaned air near its dewpoint to at least one high pressure column; reboiling the first and second columns by indirect heat exchange with the reflux portion of the HP column; and distilling the supply air to the liquid N 2 and the liquid mixture of N 2 and O 2 in the HP column.

Claim 4

The process according to claim 2 wherein the first and second columns are operated over approximately the same temperature range, within the range of 80 K to 100 K, and the first column operates at an average pressure at least 5% higher than the second column average pressure.

Claim 5

The process according to claim 3 wherein the second column bottom product is gaseous O 2 at a purity in the range of 90 to 99%.

Claim 6

The process according to claim 3 wherein the first column overhead nitrogen is the useful product and the second column bottom product is gaseous O 2 at a purity in the range of 70 to 85% O 2 .

Claim 7

The apparatus according to claim 1 further comprising means to supply air which has been pressurized and cooled to near its dewpoint as the mixture, and wherein N 2 is the more volatile fraction.

Claim 8

In an apparatus, comprising elements designed, dimensioned and arranged for distilling multi-component gas mixture at subambient temperatures, including; first means for generating reboil and rectifying the multi-component feed mixture to a substantially pure first component overhead liquid and a liquid bottom mixture enriched in a second component; a first LP column; a second LP column; means for providing reboil to said first and second LP columns from said first means; means for feeding said liquid bottom mixture from said first means to said first LP column; means for feeding the liquid bottom product from said first LP column to said second LP column; means for feeding the overhead of said second LP column to said first LP column; means for refluxing the second LP column by indirect meat exchange with at least part of said first component liquid; means for withdrawing a substantially pure first component stream from the top of said first LP column; means for withdrawing a substantially pure second component stream from the bottom of said second LP column.

Claim 9

In an apparatus, comprising elements designed, dimensioned and arranged for distilling multi-component gas mixture at subambient temperatures, including; first means for generating reboil and rectifying the multi-component feed mixture to a substantially pure first component overhead liquid and a liquid bottom mixture enriched in a second component; a first LP column; a second LP column; means for providing reboil to said first and second LP columns from said first means; means for feeding said liquid bottom mixture from said first means to said first LP column; means for feeding the liquid bottom product from said first LP column to said second LP column; means for feeding the overhead of said second LP column to said first LP column; means for refluxing the second LP column by indirect meat exchange with at least part of said first component liquid; means for withdrawing a substantially pure first component stream from the top of said first LP column; means for withdrawing a substantially pure second component stream from the bottom of said second LP column.