US 5,331,818 A · Air separation

Abstract

Air is rectified in a rectification system comprising a higher pressure rectification column, an intermediate pressure rectification column, and a lower pressure rectification column. A first reboiler-condenser provides liquid nitrogen reflux for the higher pressure rectification column and for the lower pressure rectification column and also reboils the intermediate pressure rectification column. Another reboiler-condenser provides liquid nitrogen reflux for the intermediate pressure rectification column and reboils the lower pressure rectification column. Air is fed to the higher pressure rectification column through a pair of inlets. A first oxygen product is withdrawn from the intermediate pressure rectification column by a pump. Gaseous nitrogen products are withdrawn from the intermediate and lower pressure rectification columns through a pair of outlets thereof.

Claims23

Dependent claims

A method of separating air, comprising:

rectifying air in a rectification system comprising a higher pressure rectification column, a lower pressure rectification column and an intermediate pressure rectification column;
providing each column with liquid nitrogen reflux;
employing vapour from the higher pressure rectification column to reboil liquid obtained in the intermediate pressure rectification column and vapour from the intermediate pressure rectification column to reboil liquid obtained in the lower pressure rectification column;
introducing a stream of feed air into the higher pressure rectification column;
withdrawing a first oxygen product and a first gaseous nitrogen product from the intermediate pressure rectification column;
and also withdrawing a second nitrogen product or stream from the lower pressure rectification column.

3 more elements

An apparatus for separating air comprising:

a higher pressure rectification column,
a lower pressure rectification column;
and
an intermediate pressure rectification column;
means for providing each rectification column with liquid nitrogen reflux;
a first reboiler for reboiling, by heat exchange with vapour from the higher pressure rectification column, liquid obtained in the intermediate pressure rectification column;
a second reboiler for reboiling, by heat exchange with vapour from the intermediate pressure rectification column, liquid obtained in the lower pressure rectification column;
an inlet to the higher pressure rectification column for a feed air stream;
an outlet from the intermediate pressure rectification column for the withdrawal of a first oxygen product;
an outlet from the intermediate pressure rectification column for the withdrawal of a first gaseous nitrogen product;
and
an outlet from the lower pressure rectification column for the withdrawal of a second nitrogen product or stream.

9 more elements

Dependencies are inferred from the claim text.

Air separation

Life of this patent

Air separation

Life of this patent

Abstract

Claims23