Method and apparatus for liquefying a CO2-rich gas

Patent metadata

Field	Value
Publication number	US-12504226-B2
Application number	US-202218280052-A
Country	US
Kind code	B2
Filing date	Feb 28, 2022
Priority date	Mar 4, 2021
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

An apparatus for separation of a flow containing at least 95 mol % of carbon dioxide and also at least one impurity lighter than carbon dioxide by distillation comprises a heat exchanger ( 20 ), a distillation column ( 30 ), expansion means (V 3 ), means for sending the flow to be cooled in the heat exchanger, means for sending the cooled flow to be separated in the distillation column, means for withdrawing at the bottom of the column a liquid flow containing at least 99 mol % of carbon dioxide, means for sending at least a portion ( 12 ) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid ( 3 ), means for sending at least a portion of the subcooled liquid to the expansion means to produce a two-phase flow, a phase separator ( 40 ) for separating the two-phase flow to form a gas and a liquid, means for sending at least a portion ( 14 ) of the liquid from the phase separator to be vaporized in the heat exchanger and means for taking a portion ( 4 ) of the liquid from the phase separator.

First claim

The invention claimed is:

1 . A process for the separation of a flow ( 1 , 2 ) containing at least 95 mol % of carbon dioxide and also at least one impurity lighter than carbon dioxide by distillation, wherein:
i) cooling the flow in a heat exchanger ( 20 ) and separated in a distillation column ( 30 ) or by a partial condensation step in a separator vessel; ii) withdrawing a liquid flow containing at least 99 mol % of carbon dioxide at the bottom of the column or vessel; iii) sending a portion ( 12 ) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid; iv) expanding at least a portion of the subcooled liquid to produce a two-phase flow; v) separating the two-phase flow to form a gas and a liquid and sending at least a portion of the liquid ( 14 ) to be heated in the heat exchanger by indirect heat exchange with at least a portion of the flow that is to be separated and with the at least a portion of the liquid that is to be subcooled, the at least a portion of the liquid vaporizing in the heat exchanger; vi) producing a first liquid product by: (a) taking a portion ( 4 ) of the liquid ( 8 ) from step v), optionally after pressurization in a pump ( 50 , 55 ) or (b) taking a portion ( 4 ) of the subcooled liquid; vii) producing a second liquid product ( 5 ) by taking a portion of the bottom liquid from the column or vessel without cooling the portion of the bottom liquid in the heat exchanger ( 20 ) and preferably without expanding the portion of the bottom liquid; and viii) producing the first liquid product and the second liquid product ( 4 , 5 ) are produced simultaneously.

2 . The process as claimed in claim 1 , with variant vi) (a), wherein all of the subcooled liquid ( 3 ) is expanded to produce the two-phase flow and a portion of the liquid ( 14 ) from step v) is sent to be vaporized in the heat exchanger ( 20 ).

3 . The process as claimed in claim 1 , with variant vi) (b), wherein a portion ( 3 ) of the subcooled liquid is expanded to produce the two-phase flow and all of the liquid ( 14 ) from step v) is sent to be vaporized in the heat exchanger ( 20 ).

4 . The process as claimed in claim 1 , wherein the gas ( 16 ) from step v) is heated in the exchanger ( 20 ).

5 . The process as claimed in claim 1 , wherein the liquid vaporized ( 18 ) in the exchanger ( 20 ) is sent to be mixed with the flow that is to be cooled ( 2 ) upstream of the exchanger.

6 . A process for the separation of a flow containing at least 95 mol % of carbon dioxide and also at least one impurity lighter than carbon dioxide by distillation, wherein according to a first and a second mode of operation:
cooling the flow in a heat exchanger ( 20 ) and separated in a distillation column ( 30 ) or a separator vessel; ii) withdrawing a liquid flow containing at least 99 mol % of carbon dioxide at the bottom of the column or vessel; and iii) sending at least a portion ( 12 ) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid ( 3 ); iv) expanding at least a portion of the subcooled liquid to produce a two-phase flow; v) the two-phase flow is separated to form a gas ( 16 ) and a liquid ( 8 , 14 ) and at least a portion ( 14 ) of the liquid is sent to be heated in the heat exchanger by indirect heat exchange with at least a portion of the flow that is to be separated and with the at least a portion of the liquid that is to be subcooled, the at least a portion of the liquid vaporizing in the heat exchanger; and vi) wherein
a) according to the first mode of operation,
a′) a portion of the liquid from step v) is taken as first liquid product ( 4 ), or
b′) a portion of the subcooled liquid is taken as first liquid product and

b) according to the second mode of operation, a portion ( 5 ) of the bottom liquid is taken as second liquid product without subcooling it in the heat exchanger, no portion of the liquid from step v) is taken as first liquid product, all of the liquid from step v) being vaporized in the heat exchanger, and no portion of the subcooled liquid is taken as the first liquid product.

7 . The process as claimed in claim 6 , wherein the liquid product ( 4 ) is at between 6 and 8 bara and/or a portion of the liquid flow is taken without subcooling it to form a product ( 5 ) at between 10 and 40 bara, preferably between 13 and 20 bara.

8 . The process as claimed in claim 6 , wherein a common pump ( 55 ) is used to bring,
a) during the first mode, the portion of the subcooled liquid or a portion of the liquid from step v) to its final pressure to form the first product and, b) during the second mode, the portion of the bottom liquid not cooled in the heat exchanger to its final pressure to form the second product.

9 . An apparatus for the separation of a flow containing at least 95 mol % of carbon dioxide and also at least one impurity lighter than carbon dioxide by distillation comprising:
a heat exchanger ( 20 ); a distillation column ( 30 ) or a separator vessel; expansion means (V 3 ); means for sending the flow to be cooled in the heat exchanger; means for sending the cooled flow to be separated in the distillation column or in the vessel; means for withdrawing at the bottom of the column or vessel a liquid flow containing at least 99 mol % of carbon dioxide; means for sending at least a portion ( 12 ) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid ( 3 ); means for sending at least a portion of the subcooled liquid to the expansion means to produce a two-phase flow; a phase separator ( 40 ) for separating the two-phase flow to form a gas and a liquid; means for sending at least a portion ( 14 ) of the liquid from the phase separator to be heated in the heat exchanger by indirect heat exchange with at least a portion of the flow that is to be separated and with the at least a portion of the liquid that is to be subcooled; means for taking a portion ( 4 ) of the liquid from the phase separator or of the subcooled liquid as liquid product at a first pressure; and means for supplying liquid that has not been subcooled as liquid product at a second pressure connected to the means for withdrawing a liquid flow at the bottom of the column or vessel.

10 . The apparatus as claimed in claim 9 , further comprising means for sending liquid from the phase separator vaporized in the heat exchanger ( 20 ) to be mixed with the flow that is to be separated ( 1 ) upstream of the heat exchanger.

11 . The apparatus as claimed in claim 9 , wherein the heat exchanger ( 20 ) has two ends, one designed to operate at a hotter temperature than the other, the means for sending the flow that is to be separated ( 1 ) to be cooled in the exchanger being connected to the end designed to operate at the hotter temperature and the means for sending the cooled flow ( 4 , 6 ) to be separated in the distillation column or in the vessel being connected to the end designed to operate at the colder temperature.

12 . The apparatus as claimed in claim 9 , wherein the heat exchanger ( 20 ) has two ends, one designed to operate at a hotter temperature than the other, the means for sending at least a portion ( 12 ) of the liquid flow to be cooled in the heat exchanger to form a subcooled liquid ( 3 ) being connected to the end designed to operate at the colder temperature.

13 . The apparatus as claimed in claim 9 , wherein the heat exchanger ( 20 ) has two ends, one designed to operate at a hotter temperature than the other, the means for sending at least a portion ( 14 ) of the liquid from the phase separator to be heated in the heat exchanger being connected to t

Assignees

• Air Liquide

Inventors

• Tran Michael
• Granados Ludovic
• Leclerc Mathieu
• Rodrigues Guillaume
• Troptard Aurore

Classifications

• F25J2215/80

  Carbon dioxide · CPC title

• F25J2210/80

  Carbon dioxide · CPC title

• F25J2290/34

  Details about subcooling of liquids · CPC title

• F25J2235/80

  the fluid being carbon dioxide · CPC title

• F25J2270/80

  Quasi-closed internal or closed external carbon dioxide refrigeration cycle · CPC title