Process for obtaining one or more air products and air separation plant

Patent metadata

Field	Value
Publication number	US-11098950-B2
Application number	US-201815995742-A
Country	US
Kind code	B2
Filing date	Jun 1, 2018
Priority date	Jun 2, 2017
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

The invention proposes a process and an air separation plant comprising a rectification column system comprising a high-pressure column, a low-pressure column, a main heat exchanger, and a main air compressor. The total air supplied to the rectification column system is compressed in the main air compressor to a first pressure level. The high-pressure column is operated at a second pressure level, at least 3 bar below the first pressure level. A gaseous, nitrogen-rich fluid is removed from the high-pressure column and warmed up in the gaseous state without prior liquefaction. A first partial quantity of the gaseous, nitrogen-rich fluid is warmed to a first temperature level of −150 to −100° C., supplied at this first temperature level to a booster and compressed further to a third pressure level. The first partial quantity is then warmed to a second temperature level and discharged from the air separation plant.

First claim

The invention claimed is:

1. A process for obtaining one or more air products using an air separation plant having a rectification column system comprising a high-pressure column, a low-pressure column, a main heat exchanger, and a main air compressor, said process comprising:
compressing all feed air that is to be supplied to the rectification column system in the main air compressor to a first pressure level, and operating the high-pressure column at a second pressure level which is at least 3 bar below the first pressure level, wherein the feed air to be supplied to the rectification column is cooled and purified before being cooled in the main heat exchanger,
removing a gaseous, nitrogen-rich fluid from the high-pressure column at the second pressure level, and warming said gaseous, nitrogen-rich fluid while in the gaseous state without prior liquefaction,
wherein a first partial quantity of the gaseous, nitrogen-rich fluid is warmed in the main heat exchanger to a first temperature level of −150 to −100° C., wherein said first partial quantity of the gaseous, nitrogen-rich fluid is supplied at the first temperature level to a booster, in which said first partial quantity of the gaseous, nitrogen-rich fluid is compressed further to a third pressure level, and
wherein, after compression to the third pressure level, said first partial quantity of the gaseous, nitrogen-rich fluid is warmed in the main heat exchanger to a second temperature level above the first temperature level and is thereafter discharged permanently from the air separation plant.

2. The process according to claim 1 , further comprising warming a second partial quantity of the gaseous nitrogen-rich fluid together with the first partial quantity of the gaseous nitrogen-rich fluid to the first temperature level in said main heat exchanger, supplying said second partial quantity of the gaseous nitrogen-rich fluid at the first temperature level to the booster, compressing said second partial quantity of the gaseous nitrogen-rich fluid to the third pressure level in said booster, cooling the second partial quantity of the gaseous nitrogen-rich fluid, after compression to the third pressure level, to a third temperature level below the first temperature level, and subsequently expanding said second partial quantity of the gaseous nitrogen-rich fluid to the second pressure level and returning said second partial quantity of the gaseous nitrogen-rich fluid to the high-pressure column.

3. The process according to claim 2 , wherein a third partial quantity of the nitrogen-rich fluid, which is not compressed to the third pressure level, is warmed to the first temperature level and discharged permanently from the air separation plant.

4. The process according to claim 1 , wherein the third pressure level is at 8 to 12 bar.

5. The process according to claim 1 , the booster is mechanically coupled to an expansion turbine.

6. The process according to claim 1 , wherein the booster is driven by external energy.

7. The process according to claim 2 , wherein the second partial quantity is 10 to 50% of the gaseous nitrogen-rich fluid removed from the high-pressure column at the second pressure level and warmed in the gaseous state without prior liquefaction.

8. The process according to claim 1 , wherein said main heat exchanger has a cold end and a warm end a first part of the feed air that is to be supplied to the rectification column system is further compressed in a further booster from the first pressure level to a further pressure level, cooled in the main heat exchanger to an intermediate temperature which is between to the temperature at the warm end of the main heat exchanger and the temperature at the warm end of the main heat exchanger, expanded to the second pressure level in an expansion turbine mechanically coupled to the further booster, and subsequently fed into the high-pressure column.

9. The process according to claim 8 , wherein a second part of the feed air that is to be supplied to the rectification column system is compressed from the first pressure level to the further pressure level in the further booster, cooled in the main heat exchanger to a temperature below said intermediate temperature, expanded to the second pressure level, and subsequently fed into the high-pressure column.

10. The process according to claim 1 , wherein a part of the feed air that is to be supplied to the rectification column system is cooled down at the first pressure level in the main heat exchanger, expanded from the first pressure level to the second pressure level, and subsequently fed into the high-pressure column.

11. The process according to claim 1 , wherein the rectification column system comprises at least one rectification column, into which a first fluid that is enriched in argon with respect to a sump liquid of the high-pressure column is transferred from the low-pressure column and depleted of argon, and a residue of the first fluid that remains after argon depletion is returned to the low-pressure column.

12. The process according to claim 11 , wherein said rectification column system includes a crude argon column and a pure argon column which provide for argon depletion of the first liquid,
said crude argon column and pure argon column are operated with top condensers in which oxygen-enriched liquid from a sump of the high-pressure column is partially evaporated, and
a non-evaporated fraction from the top condenser of the pure argon column and non-evaporated fraction from the top condenser of the crude argon column are the residue of the first liquid returned to the low-pressure column,
wherein the non-evaporated fraction from the top condenser of the pure argon column is fed into the low-pressure column at a point which is 5 to 15 theoretical separating stages above the point at which the non-evaporated fraction from the top condenser of the crude argon column is fed into the low pressure column.

13. An air separation plant for obtaining one or more air products comprising:
a rectification column system comprising a high-pressure column, a low-pressure column, a main heat exchanger, and a main air compressor,
a line for introducing feed air that is to be supplied to the rectification column system into the main compressor wherein feed air that is to be supplied to the rectification column system is compressed to a first pressure level, and wherein the high-pressure column is operated at a second pressure level which is at least 3 bar below the first pressure level,
a cooling device for cooling the feed air prior to being supplied to the rectification column system,
an adsorption device for removing water and carbon dioxide from the feed air to being supplied to the rectification column system,
a line for removing a gaseous, nitrogen-rich fluid from the high-pressure column at the second pressure level, and means for heating gaseous, nitrogen-rich fluid in the gaseous state without prior liquefaction,
one or more passages within said main heat exchanger for heating a first partial quantity of the gaseous, nitrogen-rich fluid to a first temperature level of −150 to −100° C., a line for supplying the first partial quantity of the gaseous, nitrogen-rich fluid at the first temperature level to a booster wherein the first partial quantity of the gaseous, nitrogen-rich fluid is compressed to a third pressure level, and
one or more further passages within said main heat exchanger for heating the first partial quantity of the gaseous, nitrogen-rich fluid, after compression to the third pressure level, to a second temperature level above the first temperature level and discharging the first partial quant

Assignees

• Linde Ag

Inventors

• Golubev Dimitri

Classifications

• F25J3/04412

  in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column · CPC title

• F25J3/04351

  of nitrogen · CPC title

• F25J3/04296

  Claude expansion, i.e. expanded into the main or high pressure column · CPC title

• F25J3/04175

  at a pressure of substantially more than the highest pressure column · CPC title

• F25J3/0406 Primary

  of nitrogen · CPC title