Process and apparatus for the separation of air by cryogenic distillation

摘要

The present invention relates to a process and apparatus for the separation of air by cryogenic distillation. In particular, it relates to a process for separation of air using three cryogenic distillation columns for the production of gaseous oxygen. Certain embodiments of the invention are particularly efficient for the production of gaseous oxygen at pressures between 30 and 45 bars abs, in which the oxygen is produced by removing liquid oxygen from a distillation column, pressurizing the oxygen and vaporizing the pressurized liquid by heat exchange with air.

主权项

1. A process for the separation of air by cryogenic distillation in which air is purified, cooled and sent to a first distillation column of a column system, wherein the air is separated into an oxygen enriched liquid and a nitrogen enriched gas, the process comprising the steps of:
introducing the oxygen enriched liquid or a liquid derived from the oxygen enriched liquid from the first column to a top condenser of a second column operating at a lower pressure than the first column, wherein the oxygen enriched liquid or a liquid derived from the oxygen enriched liquid is partially vaporized; warming the bottom of the second column via a bottom reboiler; introducing liquid from the bottom of the second column to an intermediate point of a third column operating at a lower pressure than the second column; introducing nitrogen enriched liquid from the top of the second column to the top of the third column; and removing oxygen rich liquid from the bottom of the third column, such that the oxygen rich liquid is pressurized and vaporized by heat exchange with air, wherein the oxygen enriched liquid from the top condenser of the second column is sent to an intermediate point of the second column to be separated within the second column.