Patent ID: 6276170
Filing Date: 2001-08-21
Classification: F25J,Y10S

Abstract:
A process for separating air by cryogenic distillation comprising the steps offeeding compressed, cooled and purified air to a high pressure column where it is separated into a first nitrogen enriched stream at the top and a first oxygen enriched stream at the bottom,feeding at least a portion of the first oxygen enriched stream to an intermediate pressure column to yield a second nitrogen enriched stream at the top and a second oxygen enriched stream at the bottom, sending at least a portion of the second nitrogen enriched stream to one of a low pressure column and a top condenser of an argon column having a bottom reboiler heated by a gas stream containing at least 95% nitrogen, sending at least a portion of the second oxygen enriched stream to a low pressure column,separating a third oxygen enriched stream at the bottom and a third nitrogen enriched stream at the top of the low pressure column, the gas stream heating the bottom reboiler of the argon column being at least a portion of one of the first, second and third nitrogen enriched streams,sending a heating gas to a bottom reboiler of the low pressure column,removing at least a portion of the third oxygen enriched stream at a removal point,removing a first argon enriched stream containing between 3 and 20% argon from the low pressure column,sending the first argon enriched stream to the argon column having a top condenser, recovering a second argon enriched stream, richer in argon than the first argon enriched stream, at the top of the argon column, removing at least part of the fourth oxygen enriched stream at the bottom of the argon column as a product stream rich in oxygen, andcompressing at least a portion of the third nitrogen enriched stream and sending it as heating gas to the bottom reboiler of the argon column.