Plant for producing oxygen by cryogenic air separation

Patent metadata

Field	Value
Publication number	US-10401083-B2
Application number	US-201615556364-A
Country	US
Kind code	B2
Filing date	Mar 10, 2016
Priority date	Mar 13, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

The plant is used for producing oxygen by cryogenic air separation. The plant has a high-pressure column, a low-pressure column and a main condenser. An argon-elimination column is in fluid connection with an intermediate point of the low-pressure column and is connected to an argon-elimination column head condenser. An auxiliary column has a sump region, into which gas is introduced from the argon-elimination column head condenser. The head of the auxiliary column is connected to a return flow liquid line, in order to introduce a liquid stream from the high-pressure column or the head condenser. The liquid stream has an oxygen content which is at least equal to that of air. At least one part of the crude liquid oxygen from the sump of the high-pressure column is fed to the auxiliary column at a first intermediate point.

First claim

What we claim is:

1. A method for producing oxygen by low-temperature separation of air in a distillation column system which comprises
a high-pressure column and a low-pressure column,
a main condenser which is a condenser evaporator having a liquefaction space and an evaporation space, wherein the liquefaction space of the main condenser is in fluid communication with the top of the high-pressure column and the evaporation space of the main condenser is in fluid communication with the low-pressure column,
an argon discharge column which is in fluid communication with an intermediate point on the low-pressure column,
an argon discharge column tops condenser which is a condenser-evaporator having a liquefaction space and an evaporation space, wherein the liquefaction space of the argon discharge column tops condenser is in fluid communication with the top of the argon discharge column,
an auxiliary column whose bottom region is configured for introduction of gas from the evaporation space of the argon discharge column tops condenser,

said method comprising:
introducing liquid crude oxygen from the bottom of the high-pressure column into the auxiliary column,
introducing a liquid stream from the high-pressure column or the main condenser as reflux into the top of the auxiliary column via a reflux liquid conduit, wherein the liquid stream has a nitrogen content at least equal to that of air, and
supplying at least a first portion of the liquid crude oxygen to the auxiliary column at a first intermediate point,
wherein the operating pressure at the top the auxiliary column is at least 50 mbar higher than the operating pressure at the top of the low-pressure column.

2. The method as claimed in claim 1 , wherein a gaseous fraction is withdrawn from the top of the auxiliary column as a gaseous nitrogen product separately from a gaseous nitrogen product stream withdrawn from the top of the low-pressure column.

3. The method as claimed in claim 1 , wherein an additional liquid fraction is introduced into the auxiliary column at a second intermediate point which is arranged above the first intermediate point.

4. The method as claimed in claim 3 , wherein the additional liquid fraction is a liquid air fraction.

5. The method as claimed in claim 1 , wherein at least a portion of liquid downflowing in the auxiliary column is collected immediately above the column bottom as collected fluid, and at least a portion of the collected liquid is introduced into the low-pressure column.

6. The method as claimed in claim 1 , wherein no gas stream is passed from the low-pressure column into the auxiliary column.

7. The method as claimed in claim 1 , wherein a second portion of the liquid crude oxygen is supplied to the auxiliary column at the bottom or to the evaporation space of the argon condenser and a third portion of the liquid crude oxygen is supplied to the low-pressure column at an intermediate point.

8. The method as claimed in claim 1 , wherein the high-pressure column and the low-pressure column are arranged side by side and the argon discharge tops condenser and the auxiliary column are arranged over the high-pressure column.

9. The method as claimed in claim 1 , wherein the argon discharge column and the argon discharge column tops condenser are arranged spatially separate from one another.

10. The method as claimed in claim 1 , wherein the argon discharge column is arranged in a dividing wall column region of the low-pressure column.

11. The method as claimed in claim 1 , wherein the mass transfer elements in the auxiliary column have an identical or higher specific surface area than those in the low-pressure column.

12. The method as claimed in claim 1 , wherein the auxiliary column and the argon discharge column tops condenser are arranged in separate containers.

13. The method as claimed in claim 1 , wherein no gas stream and no liquid stream are passed from the low-pressure column into the auxiliary column.

14. A plant for producing oxygen by low-temperature separation of air comprising:
a high-pressure column and a low-pressure column,
a main condenser which is a condenser evaporator having a liquefaction space and an evaporation space, wherein the liquefaction space of the main condenser is in fluid communication with the top of the high-pressure column and the evaporation space of the main condenser is in fluid communication with the low-pressure column,
an argon discharge column which is in fluid communication with an intermediate point on the low-pressure column,
an argon discharge column tops condenser which is a condenser-evaporator having a liquefaction space and an evaporation space, wherein the liquefaction space of the argon discharge column tops condenser is in fluid communication with the top of the argon discharge column,
an auxiliary column whose bottom region includes an inlet for introduction of gas from the evaporation space of the argon discharge column tops condenser, and via
a crude oxygen conduit for introduction of liquid crude oxygen from the bottom of the high-pressure column into the auxiliary column,
a reflux liquid conduit for introducing a liquid stream from the high-pressure column or the main condenser as reflux into the top of the auxiliary column, wherein the liquid stream has a nitrogen content which is at least equal to that of air, and
the crude oxygen conduit is configured for introducing crude oxygen into the auxiliary column at a first intermediate point,
wherein the auxiliary column is configured to operate at a pressure at the top of the auxiliary column that is at least 50 mbar higher than the pressure at the top of the low-pressure column.

15. The plant as claimed in claim 14 , further comprising means for obtaining a gaseous tops fraction from the auxiliary column as a gaseous nitrogen product separately from a gaseous tops nitrogen from the low-pressure column.

16. The plant as claimed in claim 14 , further comprising a conduit for introduction of an additional liquid fraction into the auxiliary column at a second intermediate point which is arranged above the first intermediate point.

17. The plant as claimed in claim 14 , further comprising means for collecting at least a portion of the liquid downflowing in the auxiliary column immediately above the column bottom and means for introducing the collected liquid into the low-pressure column.

18. The plant as claimed in claim 17 , wherein the high-pressure column and the low-pressure column are arranged side by side, the argon discharge column is arranged above the low-pressure column and the auxiliary column is arranged next to the combination of the low-pressure column and the argon discharge column and above the high-pressure column above the main condenser.

Assignees

• Linde Ag

Inventors

• Lochner Stefan
• Nohlen Thomas
• Kirchner Lars
• Golubev Dimitri

Classifications

• F25J3/04939

  Vertical, e.g. dividing wall columns (details of dephlegmators F25J5/007) · CPC title

• F25J3/04909

  Structured packings · CPC title

• F25J3/04896

  Details of columns, e.g. internals, inlet/outlet devices · CPC title

• F25J3/04878

  Side by side arrangement of multiple vessels in a main column system, wherein the vessels are normally mounted one upon the other or forming different sections of the same column (multiple vessels of a crude argon column F25J3/04703) · CPC title

• F25J3/04872

  Vertical layout of cold equipments within in the cold box, e.g. columns, heat exchangers etc. · CPC title