Efficient single column air separation cycle and its integration with gas turbines

摘要

The cryogenic distillation of air in a single distillation column system is improved by (a) operating the column (152) at a pressure between 70 and 300 psia (0.5 and 2 MPa); (b) withdrawing a portion (160) of the liquid oxygen bottoms having an oxygen concentration greater than 80% oxygen from the bottom of the column and reducing the pressure of and vaporizing the withdrawn liquid oxygen by heat exchange (164) against a condensing nitrogen stream (182) removed from a top section of the column; (c) feeding the condensed, nitrogen stream (184) to a top section of the column (152) as reflux; and (d) recovering the vaporized oxygen (168) as at least a substantial portion of the oxygen product. Preferably boilup is provided by boiling at least another portion of the liquid oxygen bottoms by heat exchange (142) against (a) an air stream (141) at a higher pressure than the feed air stream or (b) a recycle nitrogen stream (140) at a pressure greater than the operating pressure of the column, or by recycling a portion of the oxygen product (168) at a pressure of at least the operating pressure of the column to the bottom thereof and/or by providing intermediate boilup to the stripping section of the column by vaporizing a portion of descending column liquid by heat exchange (264) against either an air stream (141) at a higher pressure than the feed air stream or a recycle nitrogen stream (203) at a pressure greater than the operating pressure of the column.