Cryogenic distillation system for air separation

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 a low pressure column or to a top condenser of an argon column, sending at least a portion of the second oxygen enriched stream to the 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,
• 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, sending nitrogen enriched liquid to the top condenser of the argon column, and
• recovering a second argon enriched stream, richer in argon than the first argon enriched stream, at the top of the argon column and removing a fourth oxygen enriched stream at the bottom of the argon column,
• wherein the nitrogen enriched liquid sent to the argon column top condenser contains at least 90% nitrogen.

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 a low pressure column or to a top condenser of an argon column, sending at least a portion of the second oxygen enriched stream to the 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,
• 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, sending nitrogen enriched liquid to the top condenser of the argon column, and
• recovering a second argon enriched stream, richer in argon than the first argon enriched stream, at the top of the argon column and removing a fourth oxygen enriched stream at the bottom of the argon column,
• wherein the removing of the first argon enriched stream is at least 5 theoretical trays above the bottom of the low pressure column and the removing of the fourth oxygen enriched stream is as a product.

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 a low pressure column or to a top condenser of an argon column, sending at least a portion of the second oxygen enriched stream to the 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,
• 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, sending nitrogen enriched liquid to the top condenser of the argon column, and
• recovering a second argon enriched stream, richer in argon than the first argon enriched stream, at the top of the argon column and removing a fourth oxygen enriched stream at the bottom of the argon column,
• wherein the low pressure column operates at above 2 bar.

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 a low pressure column or to a top condenser of an argon column, sending at least a portion of the second oxygen enriched stream to the 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,
• 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, sending nitrogen enriched liquid to the top condenser of the argon column, and
• recovering a second argon enriched stream, richer in argon than the first argon enriched stream, at the top of the argon column and removing a fourth oxygen enriched stream at the bottom of the argon column,
• sending at least a portion of the condensed nitrogen enriched stream from a bottom reboiler of the argon column to the top condenser 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, 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 the top of the intermediate pressure column to the low pressure column or to the top condenser 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 sending a nitrogen enriched liquid to the top condenser of the argon column, a conduit for withdrawing a second argon enriched stream from the argon column and a conduit for withdrawing a fourth oxygen enriched stream from the argon column, and

• wherein the argon column has a bottom reboiler.

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, 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 the top of the intermediate pressure column to the low pressure column or to the top condenser 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 sending a nitrogen enriched liquid to the top condenser of the argon column, a conduit for withdrawing a second argon enriched stream from the argon column and a conduit for withdrawing a fourth oxygen enriched stream from the argon column, and

• means for pressurizing at least one oxygen enriched liquid withdrawn from the argon column or the low pressure 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, 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 the top of the intermediate pressure column to the low pressure column or to the top condenser 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 sending a nitrogen enriched liquid to the top condenser of the argon column, a conduit for withdrawing a second argon enriched stream from the argon column and a conduit for withdrawing a fourth oxygen enriched stream from the argon column, and

• means for sending a nitrogen enriched gas from the high pressure column to a bottom reboiler of the intermediate pressure 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, 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 the top of the intermediate pressure column to the low pressure column or to the top condenser 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 sending a nitrogen enriched liquid to the top condenser of the argon column, a conduit for withdrawing a second argon enriched stream from the argon column and a conduit for withdrawing a fourth oxygen enriched stream from the argon column, and

• means for sending at least part of the second oxygen enriched fluid to the top condenser of the intermediate pressure column,
• wherein the intermediate pressure column has a top condenser.

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, 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 the top of the intermediate pressure column to the low pressure column or to the top condenser 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 sending a nitrogen enriched liquid to the top condenser of the argon column, a conduit for withdrawing a second argon enriched stream from the argon column and a conduit for withdrawing a fourth oxygen enriched stream from the argon column, and

• means for removing the nitrogen enriched liquid to be sent to the top condenser of the argon column from the top of the low pressure column and/or the top of the intermediate pressure column and/or the top of the high pressure column and/or the bottom reboiler of the argon column.