Method and device for generating gaseous compressed nitrogen

Patent metadata

Field	Value
Publication number	US-11118834-B2
Application number	US-201414769465-A
Country	US
Kind code	B2
Filing date	Mar 18, 2014
Priority date	Mar 19, 2013
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

Method and device for generating gaseous compressed nitrogen by the low-temperature separation of air in a distillation column system, having a pre-column, a high-pressure column and a low-pressure column. The feed air is compressed, purified in a purification apparatus and cooled. A first sub-flow of the cooled feed air is introduced in a predominantly liquid state into the distillation column system. A gaseous fraction from the pre-column in introduced into the liquefaction chamber of a pre-column head condenser with liquid formed therein fed as reflux into the pre-column. A first gaseous nitrogen product fraction is drawn from the high-pressure column, heated, and obtained as first gaseous compressed nitrogen product. At least a part of the second sub-flow is introduced into the evaporation chamber of the pre-column head condenser. A third sub-flow of the cooled feed air is expanded to perform work and subsequently introduced into the liquefaction chamber.

First claim

The invention claimed is:

1. A method for generating gaseous compressed nitrogen by low-temperature separation of air in a distillation column system having a pre-column which has a pre-column head condenser/evaporator having a liquefaction chamber and an evaporation chamber, a high-pressure column and a low-pressure column, said process comprising:
compressing input air in a main air compressor to form compressed input air,
cleaning the compressed input air in a cleaning device to form cleaned input air,
cooling the cleaned input air in a main heat exchanger to form cooled input air,
feeding a first partial stream of the cooled input air in gaseous form into the pre-column,
feeding a second partial stream of the cooled input air in a predominantly liquid state into the distillation column system,
feeding a gaseous fraction from an upper region of the pre-column into the liquefaction chamber of the head condenser/evaporator wherein liquid is formed in said liquefaction chamber, and
returning at least part of the liquid formed in the liquefaction chamber to the pre-column,
wherein said low-pressure column has a low-pressure column sump condenser/evaporator which has a liquefaction chamber and an evaporation chamber,
withdrawing a first nitrogen product fraction from the high-pressure column in gaseous form, warming said first nitrogen product fraction in the main heat exchanger, and removing warmed first nitrogen product fraction from the main heat exchanger to form a first gaseous compressed nitrogen product,
feeding at least a first substream of the second partial stream into the evaporation chamber of the pre-column head condenser/evaporator,
subjecting a third partial stream of the cooled input air to pressure reduction whereby work is performed,
wherein, after said pressure reduction, the third partial stream has a pressure which is higher than an operating pressure of the low-pressure column,
wherein, after said pressure reduction, the third partial stream is fed into the liquefaction chamber of the low-pressure column sump condenser/evaporator and is at least partly liquefied there to form liquefied third partial stream,
feeding at least a substream of the liquefied third partial stream into the low-pressure column, wherein said sub stream of the liquefied third partial stream is liquefied air,
wherein the low-pressure column has an intermediate condenser/evaporator having a liquefaction chamber and an evaporation chamber,
evaporating at least part of an intermediate liquid of the low-pressure column in the evaporation chamber of the intermediate condenser/evaporator,
liquefying at least part of a gaseous head fraction from the high-pressure column in the liquefaction chamber of the intermediate condenser/evaporator to form liquid, and returning at least part of the liquid formed in the liquefaction chamber of the intermediate condenser/evaporator to the high-pressure column, and
wherein said first gaseous compressed nitrogen product is more than 35 mol % of said input air.

2. The method as claimed in claim 1 , wherein a second gaseous nitrogen product fraction is withdrawn from the pre-column in gaseous form, warmed in the main heat exchanger and removed from the main heat exchanger to form a second gaseous compressed product.

3. The method as claimed in claim 1 , wherein less than 30 mol % of said input air is fed in the liquid state into the distillation column system.

4. The method as claimed in claim 1 , wherein the quantity of oxygen-enriched streams fed in the liquid state from the pre-column and the evaporation chamber of the pre-column head condenser/evaporator into the high-pressure column and the low-pressure column is less than 14 mol % of said input air.

5. The method as claimed in claim 1 , wherein
the second partial stream is compressed, before being cooled in the main heat exchanger, to a pressure that is higher than an operating pressure of the pre-column, and is liquefied or pseudo-liquefied in the main heat exchanger, and
a liquid stream is removed from the distillation column system, brought to an elevated pressure in the liquid state, evaporated or pseudo-evaporated in the main heat exchanger.

6. The method as claimed in claim 1 , wherein a gaseous fraction from the evaporation chamber of the pre-column head condenser/evaporator is fed, in the form of a gaseous input stream, into the high-pressure column.

7. The method as claimed in claim 1 , wherein at least some sump liquid of the pre-column is fed into the evaporation chamber of the pre-column head condenser/evaporator.

8. The method as claimed in claim 1 , wherein the third partial stream is further compressed before being cooled in the main heat exchanger.

9. The method as claimed in claim 1 , wherein, after said reducing, the pressure of the third partial stream is lower than an operating pressure of the high-pressure column.

10. The method as claimed in claim 4 , wherein the total quantity of oxygen-enriched streams fed in the liquid state from the pre-column and the evaporation chamber of the pre-column head condenser/evaporator into the high-pressure column and the low-pressure column is less than 1 mol % of said input air.

11. The method as claimed in claim 1 , wherein more than 45 mol % of the input air, in the form of the first nitrogen product fraction, is withdrawn in gaseous form from the high-pressure column and warmed in the main heat exchanger.

12. The method as claimed in claim 1 , wherein
the second partial stream is compressed, before being cooled in the main heat exchanger, to a pressure that is higher than an operating pressure of the pre-column, and is liquefied or pseudo-liquefied in the main heat exchanger, and
a liquid oxygen stream is removed from the distillation column system, brought to an elevated pressure in the liquid state, and evaporated or pseudo-evaporated in the main heat exchanger.

13. The method according to claim 1 , wherein the pre-column has a head, the low-pressure column has a head, and the high-pressure column has a head, and an operating pressure at the head of the pre-column is 6 to 9 bar, an operating pressure at the head of the high-pressure column is 3 to 6 bar, and an operating pressure at the head of the low-pressure column is 1.25 to 1.7 bar.

14. A method for generating gaseous compressed nitrogen by low-temperature separation of air in a distillation column system having a pre-column which has a pre-column head condenser/evaporator having a liquefaction chamber and an evaporation chamber, a high-pressure column and a low-pressure column, said process comprising:
compressing input air in a main air compressor to form compressed input air,
cleaning the compressed input air in a cleaning device to form cleaned input air,
cooling the cleaned input air in a main heat exchanger to form cooled input air,
feeding a first partial stream of the cooled input air in gaseous form into the pre-column,
feeding a second partial stream of the cooled input air in a predominantly liquid state into the distillation column system,
feeding a gaseous fraction from an upper region of the pre-column into the liquefaction chamber of the head condenser/evaporator wherein liquid is formed in said liquefaction chamber, and
returning at least part of the liquid formed in the liquefaction chamber to the pre-column,
wherein said low-pressure column has a low-pressure column sump condenser/evaporator which has a liquefaction chamber and an evaporation chamber,
withdrawing a first nitrogen product fraction from the high-pressure column in gaseous form, warming said first nitrogen product fraction in the mai

Assignees

• Linde Ag

Inventors

• Goloubev Dimitri

Classifications

• F25J3/04915 Primary

  Combinations of different material exchange elements, e.g. within different columns · CPC title

• F25J3/04442

  in a double column flowsheet with a high pressure pre-rectifier · CPC title

• F25J2250/04

  Down-flowing type boiler-condenser, i.e. with evaporation of a falling liquid film · CPC title

• F25J3/04387

  using liquid or hydraulic turbine expansion · CPC title

• F25J3/04054

  of air · CPC title