Cryogenic distillation system for air separation
AssigneeAir Liquide Process & Construction, Inc.
InventorBao Ha
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Abstract
Air is separated in a triple column system comprising a high pressure column, an intermediate pressure column and a low pressure column. An argon enriched liquid from the low pressure column feeds an argon column. Oxygen enriched fluids containing at least 95% oxygen are removed from the argon column and optionally from the low pressure column.
Claims46
A process for separating air by cryogenic distillation comprising the steps of
- feeding 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, and
- compressing at least a portion of the third nitrogen enriched stream and sending it as heating gas to the bottom reboiler of the argon column.
An apparatus for separating air by cryogenic distillation comprising a high pressure column, an intermediate pressure column, a low pressure column having a bottom reboiler and an argon column having a top condenser and a bottom boiler, a conduit for sending air to the high pressure column, a conduit for sending at least part of a first oxygen enriched liquid from the high pressure column to the intermediate pressure column, a conduit for sending a second oxygen enriched fluid from the bottom of the intermediate pressure column to the low pressure column, a conduit for sending a second nitrogen enriched fluid from one of the top of the intermediate pressure column to the low pressure column and the top condenser of the argon column, a conduit for sending a heating gas to the bottom reboiler of the low pressure column, a conduit for removing a third oxygen enriched fluid from the low pressure column, a conduit for sending a nitrogen enriched liquid from the high pressure column to the low pressure column, a conduit for sending a first argon enriched stream from the low pressure column to the argon column, a conduit for withdrawing a second argon enriched stream from the argon column, a conduit for withdrawing a fourth oxygen enriched stream from the argon column and removing at least part of the fourth oxygen enriched stream as a product stream, a conduit for sending a third nitrogen enriched stream from the low pressure column to the bottom reboiler of the argon column, and a compressor for compressing the third nitrogen enriched stream before sending it to the bottom reboiler of the agron column.
Dependencies are inferred from the claim text.