Patent ID: 6385996
Filing Date: 2002-05-14
Classification: F25J,Y10S

Abstract:
Air separation plant for producing an oxygen-rich fluid by cryogenic distillation, comprising:a double column comprising at least one medium-pressure column and a low-pressure column which includes a reboiler for vaporizing liquid in the bottom of the low-pressure column; a mixing column; means for sending cooled and compressed air to at least the medium-pressure column; means for sending an oxygen-enriched liquid from the medium-pressure column to an injection point of the low-pressure column and a nitrogen-enriched liquid from the medium-pressure column to the low-pressure column; means for sending gas to the bottom of the mixing column; means for sending a second oxygen-enriched liquid from the low-pressure column to the top of the mixing column, the second liquid being less volatile than the gas feeding the bottom of the mixing column; means for withdrawing an oxygen-rich fluid from the low-pressure column; means for sending at least one portion of a gas from the mixing column to passages for warming the reboiler, wherein the means for sending the second liquid further comprises means for withdrawing the second liquid from the low-pressure column at a level at least 5 theoretical trays below the injection point of the low-pressure column.