Low temperature air separation process for producing pressurized gaseous product

Patent metadata

Field	Value
Publication number	US-9733013-B2
Application number	US-201414291569-A
Country	US
Kind code	B2
Filing date	May 30, 2014
Priority date	Jul 14, 2004
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

A compressed air stream is cooled in an exchanger to form a compressed cooled air stream. The stream is then cryogenically compressed in a first compressor to form a first pressurized gas stream. The first pressurized gas stream is further cooled in the exchanger, cryogenically compressed in a second compressor, and then it is cooled and partially liquefied. The cooled and partially liquefied product is then fed to a system of distillation columns. A liquid product is removed from the system of distillation columns. This product is then pressurized, vaporized and warmed in the exchanger to yield pressurized gaseous product.

First claim

What is claimed is:

1. A method for low temperature air separation, the method comprising at least two modes of operation: a peak mode and an off peak mode, wherein in the peak mode of operation, the method comprises the steps of:
providing a compressed air stream at a pressure P 0 ;
cooling the compressed air stream in a heat exchanger, the heat exchanger having a warm side, a cool side, a first intermediate point, and a second intermediate point;
withdrawing a first portion of the compressed air stream from the cool side of the heat exchanger;
withdrawing a second portion of the compressed air stream from the first intermediate point of the heat exchanger;
compressing the second portion of the compressed air stream in a first cryogenic compressor to form a first pressurized gas stream at a pressure P 1 ;
cooling the first pressurized gas stream in the heat exchanger;
withdrawing the first pressurized gas stream from the second intermediate point of the heat exchanger;
compressing the first pressurized gas stream in a second cryogenic compressor to form a second pressurized gas stream at a pressure P 2 , wherein P 2 is greater than P 1 ;
cooling the second pressurized gas stream in the heat exchanger;
withdrawing the second pressurized gas stream from the cool side of the heat exchanger
introducing said first portion of the compressed air stream and said second pressurized gas stream or a stream derived therefrom from the cool side of the heat exchanger and into a higher pressure column operating under conditions effective for the rectification of air, thereby producing an oxygen rich bottom liquid and a nitrogen rich top gas, wherein the higher pressure column has a pressure of P HP ;
providing a lower pressure column in fluid communication with the higher pressure column, the lower pressure column comprising a liquid oxygen extraction port, the liquid oxygen extraction port disposed proximate a bottom portion of the lower pressure column, wherein the liquid oxygen extraction port is in fluid communication with the cool side of the heat exchanger, wherein the lower pressure column is in fluid communication with the higher pressure column such that the lower pressure column is configured to receive the oxygen rich bottom liquid from the higher pressure column;
introducing a liquid feed stream from a liquid storage tank to a third point of the lower pressure column, wherein the liquid feed comprises a liquid selected from the group consisting of liquid oxygen, liquid nitrogen, and combinations thereof, wherein the liquid storage tank is external of the lower pressure column and the higher pressure column;
removing a liquid product from the lower pressure column;
pressurizing at least a portion of the liquid product;
vaporizing at least a portion of said liquid product; and
heating at least a portion of said liquid product to yield a gaseous product.

2. The method as claimed in claim 1 , wherein during the off-peak mode of operation, the method further comprises the step of stopping the flow of the liquid feed stream from the liquid storage tank to the lower pressure column.

3. The method as claimed in claim 2 , further comprising the step of withdrawing a liquid stream from the lower pressure column and introducing the liquid stream to the liquid storage tank.

4. The method as claimed in claim 1 , wherein the liquid storage tank receives a liquid stream from a source selected from the group consisting of an external air separation unit, a liquefaction plant, the lower pressure column, the higher pressure column, and combinations thereof.

5. The method as claimed in claim 4 , wherein the liquid storage tank receives the liquid stream from the source during periods of time when energy prices are below a price threshold.

6. The method as claimed in claim 1 , wherein the liquid feed stream is substantially free of hydrocarbons, moisture, and carbon dioxide.

7. The method as claimed in claim 1 , further comprising the step of adjusting the third point up or down the lower pressure column based on the compositional make-up of the liquid feed stream.

8. The method as claimed in claim 1 , wherein the method is practiced in the absence of a turboexpander.

9. The method as claimed in claim 1 , wherein the flow ratio of the first portion of the compressed air stream to the second portion of the compressed air stream is approximately 4:1.

10. The method as claimed in claim 1 , wherein the cooling steps are conducted in a plurality of heat exchangers.

11. The method as claimed in claim 1 , wherein the cooling steps are conducted in one heat exchanger.

Assignees

• Air Liquide
• L'Air Liquide Société Anonyme Pour L'Étude Et L'Exploitation Des Procedes Georges Claude

Inventors

• Brugerolle Jean-Renaud
• Ha Bao

Classifications

• F25J2230/08

  Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler · CPC title

• 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

• F25J3/04012 Primary

  by compression of warm gaseous streams; details of intake or interstage cooling (F25J3/04048 takes precedence; operation of compressors F25J3/04781; particular layout of compressors used in air fractionation units F25J3/04866) · CPC title

• F25J3/04109

  Arrangements of compressors and /or their drivers (using work extraction by mechanical coupling of compression and cold expansion F25J3/04381) · CPC title

• F25J3/04054 Primary

  of air · CPC title