Recycle liquefier process

• US 4,894,076 A
• Filed: 01/17/1989
• Issued: 01/16/1990
• Est. Priority Date: 01/17/1989
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Dobracki, Thaddeus N., Dubbs, John D., Peterson, Janice C., McGuinness, Roger M.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US07/297,463
• Time in Patent Office: 364 Days
• Field of Search: 62/9, 62/36, 62/38, 62/39
• US Class Current: 62/650
• CPC Class Codes: F25J 1/0015 Nitrogen
• CPC Class Codes: F25J 1/0037 of a return stream
• CPC Class Codes: F25J 1/004 by flash gas recovery F25J1/0267 takes precedence
• CPC Class Codes: F25J 1/0042 by liquid expansion with extraction of work
• CPC Class Codes: F25J 1/0202 in a quasi-closed internal refrigeration loop F25J1/0208, F25J1/0219, F25J1/0224 take precedence
• CPC Class Codes: F25J 1/0208 in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop F25J1/021 takes precedence
• CPC Class Codes: F25J 1/0234 Integration with a cryogenic air separation unit cryogenic separation of air F25J3/04
• CPC Class Codes: F25J 1/0288 using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
• CPC Class Codes: F25J 2230/20 Integrated compressor and process expander; Gear box arrangement; Multiple compressors on a common shaft
• CPC Class Codes: F25J 2240/12 the fluid being nitrogen
• CPC Class Codes: F25J 2245/42 the recycled stream being nitrogen
• CPC Class Codes: F25J 2270/06 with multiple gas expansion loops
• CPC Class Codes: F25J 2270/90 External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
• CPC Class Codes: F25J 3/0403 of nitrogen
• CPC Class Codes: F25J 3/04224 Cores associated with a liquefaction or refrigeration cycle
• CPC Class Codes: F25J 3/04278 using external refrigeration units, e.g. closed mechanical or regenerative refrigeration units
• CPC Class Codes: F25J 3/04357 and comprising a gas work expansion loop
• CPC Class Codes: F25J 3/04381 using work extraction by mechanical coupling of compression and expansion so-called companders
• CPC Class Codes: F25J 3/04387 using liquid or hydraulic turbine expansion

Abstract

The present invention is a liquefaction process for atmospheric gases. In the process, one or more atmospheric gas streams (e.g., air, nitrogen, etc.) are compressed in a compression zone to provide both an intermediate stream and a high pressure stream. The high pressure stream is then cooled and at least a portion of it is expanded to provide refrigeration. The remaining high pressure stream is then further cooled and expanded whereby it is partially liquefied and separated into a vapor stream and a liquid atmospheric gas product stream. The intermediate pressure stream is cooled and at least a portion of it is expanded to provide refrigeration. The remaining intermediate pressure stream is further cooled and combined with the expanded portion of the high pressure stream and expanded to provide refrigeration. The discharge from this expansion, the vapor stream, and the discharge of the expansion of the portion of the intermediate pressure stream are warmed and recycled to the compression zone. The process of the present invention can include the use of companders and a dense-fluid expander.

Claims

1. A process for the liquefaction of an atmospheric gas comprising:

(a) compressing in a compression zone one or more atmospheric gas feed streams to produce an intermediate pressure stream and a high pressure stream;

(b) cooling the high pressure stream;

(c) removing at least a portion of the high pressure stream as a high pressure stream, side-stream and expanding the high pressure stream, side-stream in a first expansion step thereby providing refrigeration and producing a first expansion discharge;

(d) further cooling and expanding the cooled high pressure stream in a second expansion step thereby producing a partially liquefied second expansion discharge;

(e) phase separating the partially liquefied second expansion discharge into a vapor stream and a liquid product stream;

(f) removing at least a portion of the intermediate pressure stream as an intermediate pressure stream, side-stream and expanding the intermediate pressure stream, side-stream in a third expansion step, thus providing refrigeration and producing a third expansion discharge;

(g) cooling the intermediate pressure stream;

(h) combining the cooled intermediate pressure stream of step (g) the first expansion discharge of step (c) to form a first combined stream, and expanding the first combined stream in a fourth expansion step, thus providing refrigeration and producing a fourth expansion discharge; and

(i) warming and subsequently recycling to the compression zone the fourth expansion discharge of step (h), the vapor stream from step (e) and the third expansion discharge of step (f).

2. The process of claim 1, wherein each of the first, second, third and fourth expansion steps comprises expansion through a turboexpander.

3. The process of claim 1 wherein the compression in the compression zone comprises multiple stages of centrifugal compression.

4. The process of claim 1 wherein the cooling of the high pressure and intermediate pressure streams is accomplished by heat transfer with the vapor stream, the third expansion discharge, and the fourth expansion discharge, and wherein the heat transfer is accomplished in an integrated heat exchange zone.

5. The process of claim 1 wherein at least part of the cooling of the intermediate pressure stream is provided by an external refrigeration source.

6. The process of claim 1 wherein the atmospheric gas is nitrogen.

7. The process of claim 1 wherein each of the first, second, third and fourth expansion steps comprises expansion through a turboexpander;

the compression in the compression zone comprises multiple stages of centrifugal compression; and

work of compression for one or more of the stages of centrifugal compression is provided by work of expansion from one or more of the turboexpanders.

8. A process for the liquefaction of an atmospheric gas comprising:

(a) compressing in a compression zone one or more atmospheric gas feed streams to produce an intermediate pressure stream and a high pressure stream;

(b) cooling the high pressure stream;

(c) removing at least a portion of the high pressure stream as a high pressure stream, side-stream and expanding the high pressure stream, side-stream in a first expansion step thereby providing refrigeration and producing a first expansion discharge;

(d) further cooling and expanding the cooled high pressure stream in a second expansion step thereby producing a partially liquefied second expansion discharge;

(e) phase separating the partially liquefied second expansion discharge into a vapor stream and a liquid product stream;

(f) removing at least a portion of the intermediate pressure stream as an intermediate pressure stream, side-stream and expanding the intermediate pressure stream, side-stream in a third expansion step, thus providing refrigeration and producing a third expansion discharge;

(g) cooling the intermediate pressure stream;

(h) combining the cooled intermediate pressure stream of step (g) the first expansion discharge of step (c) to form a first combined stream, and expanding the first combined stream in a fourth expansion step, thus providing refrigeration and producing a fourth expansion discharge;

(i) combining the fourth expansion discharge of step (h) with the vapor stream from step (e) to produce a second combined stream, and warming the second combined stream;

(j) combining the second combined stream of step (i) with the third expansion discharge of step (f) to form a low pressure recycle stream; and

(k) warming the low pressure recycle stream of step (j) and returning the warmed, low pressure stream to the compression zone.

9. In a process for the cryogenic separation of air, wherein air is cooled and fed to a distillation zone comprising a high pressure and a low pressure column for fractionation thereby producing at least one gaseous nitrogen stream, the improvement for liquefying the gaseous nitrogen streams comprises:

(a) compressing in a compression zone one or more gaseous nitrogen streams to produce an intermediate pressure stream and a high pressure stream;

(b) cooling the high pressure stream;

(c) removing at least a portion of the high pressure stream as a high pressure stream, side-stream and expanding the high pressure stream, side-stream in a first expansion step thereby providing refrigeration and producing a first expansion discharge;

(d) further cooling and expanding the cooled high pressure stream in a second expansion step thereby producing a partially liquefied second expansion discharge;

(e) phase separating the partially liquefied second expansion discharge into a vapor stream and a liquid nitrogen product stream;

(f) removing at least a portion of the intermediate pressure stream as an intermediate pressure stream, side-stream and expanding the intermediate pressure stream, side-stream in a third expansion step, thus providing refrigeration and producing a third expansion discharge;

(g) cooling the intermediate pressure stream;

(h) combining the cooled intermediate pressure stream of step (g) the first expansion discharge of step (c) to form a first combined stream, and expanding the first combined stream in a fourth expansion step, thus providing refrigeration and producing a fourth expansion discharge; and

(i) warming and recycling to the compression zone the fourth expansion discharge of step (h), the vapor stream from step (e) and the third expansion discharge of step (f).