AIR SEPARATION METHOD AND APPARATUS

摘要

Provided is an air separation method and apparatus in which consumed power source can be reduced when oxygen is collected in a three-column process, including:
a first separation step in which feed air is separated into high pressure nitrogen gas and high pressure oxygen-enriched liquid air;
a second separation step in which a high pressure oxygen-enriched liquid air is separated into medium pressure nitrogen gas, and medium pressure oxygen-enriched liquid air;
a first indirect heat exchange step in which a medium pressure nitrogen gas is condensed and a low pressure oxygen-enriched liquid air is vaporized by indirect heat exchange;
a third separation step in which a low pressure oxygen-enriched air is separated into low pressure nitrogen gas and low pressure liquid oxygen;
a second indirect heat exchange step in which a high pressure nitrogen gas is condensed and a low pressure liquid oxygen is vaporized by indirect heat exchange;
a third indirect heat exchange step in which a high pressure nitrogen-enriched air in an intermediate stage in the first separation step is condensed and a medium pressure oxygen-enriched liquid air is vaporized by indirect heat exchange; and
a product gas collecting step in which low pressure oxygen gas and/or low pressure liquid oxygen is/are collected as a product oxygen gas after heat recovery.