US1602535A

US1602535A - Separation of gaseous mixtures

Info

Publication number: US1602535A
Application number: US673929A
Authority: US
Inventors: Rouge Jean Le
Original assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 1923-03-10
Filing date: 1923-11-10
Publication date: 1926-10-12
Anticipated expiration: 1943-10-12
Also published as: GB212533A; FR574668A

Description

Oct. 12 1926.

J. LE ROUGE SEPARATION OF GASE OUS MIXTURES Filed Nov. 10, 1923 BY I 52; M v M 44 ATTORNEYS Patented Oct. 12, 1926.

UNITEDSTATES PATENT OFFICE.

' man 'LE noueE, 0E nc "JLOGNE, FRANCE, assrenoa ro socrE'rE LAIR LroUrnE (SOOIE'IE ANONYHE roUE LETUDE ET LEXILOITATION nEs raocEnEs eEoaeEs creams), 0E rams, FRANCE.

SEPARATION OE GASEOUS MIXTURES.

Application and November 10, ms, Serial No. 673.929, at in France March 10, 1923.

This invention relates to the separation of the constituents of gaseous mixtures by liquefaction and rectification, and articularly to improvements whereby the e cienc of such separation is materially increase In Letters Patent of the United States, No. 981,748, a method is disclosed in which a compressed gaseous mixture is subjected to'lieat-inte'rchange with the gaseous products of the se aration and a part thereof is expanded wit the production of external work and then liquefied and separated in a rectification column while the remainder is liquefied at its initial pressure by heat-interchange with cold roducts of the se aration in which the liquid portion is uti ized.

' In this process the initial pressure of all uniform, the S0 parts of the entering gaseous mixture is pressure being selected so that the expansion of a part of the gaseous mixture w1t-h external work produces refrigeration which just sufiices to compensate for losses of cold inqthe operation.

It is the object of the present-invention to increase the eflicienc of liquefaction processes and particular yto modify and improve the process described in said Letters Patent.

Further ob'ects and advantages of the in vention will e apparent'as it is better understood by reference to the following s ecification and accompanying drawing w ich illustrates diagrammatically a form of apparatus adapted to the accomplishment of the present pu use. It is to be understood that details'of t e apparatus which are well understood by thosev skilled in the art-have been omitted from the drawing and that other details, articularly with reference to the rectification, may be varied without departing from the invention or sacrificing 'the advantages thereof.

. The present invention deperids upon the initial compression of a portion of the gaseous mixture entering t e system to a materially higher pressure than that to which the remaining portion is subjected. This portion of the gaseous mixture at high pressure is caused to travel through a temperature exchanger wherein it is subjected to ivered to a suitable expansion device such as an engine or turbine and expanded with external work to a relatively low pressure corres onding substantially to the pressure at whlch rectification is subsequently conducted. The cold expanded mixture from the engine or turbine is delivered to a liquefier wherein it is sub'ected to'heat-interchange with a body 0 liquid resulting from the rectification. 'Heat-interchan e between the gaseous mixture and the iquid results in liquefaction of the former and evaporation of the latter, and the liquid formed is preferably augmented by theliquid previously produced from the high' pressure portion of the entering gaseous mixturewhich is delivered under the control of a valve to the liquefier.

The combined liquids are then subjected to rectification in any suitable manner, for example, by causing them to descend through a column in which the are subjected to vapors resulting from t e va rization. of liquid at the bottom of the co umn. Rectification results in the separation of the constituents of the liquid, the more volatile constituents accumulating in the risin vapors while the less volatile are retaine descending liquid. In the case of air the rectification results in the reduction of a body of liquid which is $11 stantially pure The mingled in the oxygen at the bottom of the column. The

-ly cold, are utilize operation while the-balance rises as a rectifying agent through the column. The other product is nitrogen containing more or less oxygen which is withdrawn from the top of the column. Both roducts, being extremed by heat-interchange to cool the incoming gaseous mixture.

'The process may be modified by eliminating the expansion valve through which the gaseous mixture at high pressure passes after initial cooling. Instead of utilizing such a valve that part of the gaseous mixture which is not liquefied by the prelimina cooling may be caused to pass through a suitable expansion device such as an engine or turbine wherein it is sub'ected to expansion with external work. may be delivered then to theliquefier with the expanded rtion of' the mixture which has been previously compressed to a comparatively low pressure.

Referring to the drawing and applying the invention particularly to the treatment of air, a portion of the air is compressed to a comparatively low pressure, ten atmos- Q 'heres -for 'exam le and enters an exchanger B at A. It circulates in the exchanger countercurrent to separated oxygen and nitrogen traveling through the tubes B of the exchanger. The compressed air after cooling leaves the exchanger through a pipe C and is delivered to an expander D wherein it is expanded with external work. The cold expanded mixture is delivered through it a pipe M to a coil -M in thebottom of a column N wherein it is subjected to the cooling effect of a body of liquid oxygen accumulated in the bottom of the column.

7 The other portion of the air,for example, one-sixth of the total air treated, is com- .pressed to ahigh pressure, two hundred atmospheres, for example, and enters a temperature exchanger F through a pipe E. In

-passing through the tubes F of the exchanger the air is subjected to heat-interchange with a cold product of the rectification such as the efiiuent nitrogen delivered from the top of the column through a pipe X. The liquefied portion of the gaseous mixture eventually with a part of the'gaseous mixture under high pressure is delivered through an expansion valve G to a reservoir H under a pressure which is the same as that of the first portion of air and the liquid separates from the gas in the reservoir H. This latter gas is delivered through a pipe I to the pipe C wherein it joins the low pressure gaseous mixture and is delivered to the expander D. The liquid from the reservoir H is delivered through a-valve L to the pi e MT leading to thecoilM, where it joins t e cold expanded gases from the expander D.

The-liquid formed in and delivered to the 0011 M is transferred throu h controlled by a l gfo' wq, zthe e cold expanded mixture liquid in the bottom of the column is dea pipe 0 column N and flows downwardly therein over a plurality of trays N of the usual 1 .form" employed in rectification columns.

tion and separation of nitrogen from the liquid which descends to the bottom of the column as substantially pure oxygn. The nitro en or mixture of nitrogen and oxygen forming the efiluent from the column escapes through t e pipe X to the exchanger F. After passing. through the exchanger 2. portion of the efliuent escapes through the outlet and the remainder is delivered through a pipe R tothe exchanger B where it serves to cool the incoming gaseous mixture. Thev gaseous oxygen produced by vaporization of livered through a pipe T to another section of the exchanger B. The efliuent nitrogen escapes from the exchanger B through an. outlets and the oxygen escapes through an outlet U. y

An advantage of the process as described results from the possibility of compressing the major portion of the gaseous mixture to a relatively low pressure. Onlyso much of the gaseousmixture is compressed to a high pressure as is necessary to supply an amount of liquid equivalent to the losses which inevitably occur in the system. The invention is particularly desirable in connection with large installments adapted to handle great no volumes of gases.

I claim I 1. The process of-separating the constituents of gaseous mixtures by liquefaction and rectification, which comprises initially compressing a portion of the total volume of the 105 mixture to be treated to a high pressure, partially expanding this portion, compressmg the balance of the gaseous mixture to a lower pressure, expanding this portion with external work, combining both portions under conditions effecting liquefaction thereof and subjecting the liquid formed to rectification.

2. The process of separating the constituents of gaseous mixtures by liquefaction and rectification, which comprises initially coma pressing the gaseous mixture to a high pressure, expanding the mixture, by throttling to an intermediate pressure, whereby it is partially liquefied, expanding the unliquefied 12 residue with external work, subjecting the expanded residue to conditions effecting li uefaction thereof. combining this liquid with the liqfiiid producedby throttling and :pbjecting t e combined liquids to rectificaion.

3. The process of separating the constituents ofgaseous mixtures by liquefaction and rectification, which comprises initially compressing a portion of the total volume of the 1% sure, partially expandin gaseous mixture to be treated, compressing the balance of the gaseous mixture to a. higher pressure, expanding the highly compressed portion to the pressure of the other portion, expanding both portions with external work, liquefying the expanded gaseous tion of aseous mixtures, employin with production 0 mixture and subjecting the liquid to rectification.

5. The process of separating the constituents of gaseous mixtures by 'liquefaction and rectification, which comprises initially compressing a portion of the gaseous mixture to be treated to a high pressure, expanding this portion by throttling to an intermediate pressure, separating the liquid formed from the gaseous portion, compressing the balance of the gaseous mixture to substantially the intermediate pressure, combining theunliquefied residue with this compressed balance of the gaseous mixture, ex-

panding the combined gases with external work, liquefying the expanded gases and rectifying the liquid formed with the liquid above separated.

6. Improvements in processes of separaexpan- SIOIl wit separated gas or gases upon leaving the separation apparatus proper cool down a part of the gaseous mixture to be treated in order to liquefy it totally or partially, consisting in compressing this'latter part of the gaseous mixture to a pressure higher than that of the other part, then expanding by simple throttling the liquid thus produced with eventually a part of the gas, to a pressure intermediate between the very high pressure'and the pressure of the separation apparatus proper; then expanding external work the gaseous part resultin from the preceding expansion, and then liquefying and separating this gaseous part in the separation'apparat-us proper. p v i 7 A mode of operation according to claim 6, consisting in that the intermediate expansion of that part of the gaseous mixture which. is at very high pressure takes place at the initial pressure of the other part of the gaseous mixture treated;

8. A mode of operation of the process, according to claim 7, consisting in mixing external work and in w ich the the gaseous part resulting from the expansion to intermediate pressure with the other part of the other gaseous mixture treated as the latter leaves the exchangers and then expanding together these two gaseousjparts with production of external work.

9. In the application of the process, according to claim 6, to the separation of air, a mode of operating consisting in causing the nitrogen leaving the rectification column to cool down, first the air compressed to the highest pressure and then delivering a part only of this nitrogen, thus partially reheated into the exchanger carrying the part of the air at lower pressure.

- 10. Improvements in processes of separation of gaseous mixtures em loying expansion with external work an in which the separated gas or gases upon leaving the separation apparatus proper cool down a part of the gaseous mixture to be treated in order to liquefy it partially, consisting in compressing this latter part of the gaseous mixture to a pressure higher than that of the other part, then expanding with production of external work the gaseous part resulting from the partial liquefaction and then liquefying and separating this gaseous part in the separation apparatus proper.

11. The process of separating the constituents of gaseous mixtures by liquefaction and rectification, which comprises initially compressing a portion of the total volume of the mixtureto be treated to a high pressure, cooling this portion, separating the liquid formed from the gaseous portion, partially expanding this gaseous portion with external work, compressing the balance of the gaseous mixture to a lower ressure, cooling and partially expanding t is ortion with external work, subjectm 'bot expanded gaseous portions to li 'ue action and rectification and using the a ove separated liquid for this rectification.

12. The process of separating the constituents of gaseous mixtures by liquefaction and.

rectification, which com rises initially compressing a portion of t e total volume of themixture to be treated to a high ressure, cooling and partially expanding t is portion by throttling, separating the liquid formed from the gaseous portion, partially expanding this gaseous portion-with external work, compressing the balance of the gaseous mixture to a lower pressure, cooling and partially expanding this portion with external work, subjecting both expanded aseous portions to liquefaction and recti cation and using the above separated liquidfor this rectification.

13. The process of separatin the constituents of gaseous mixtures by hquefaction and rectification, which comprises initially compressing a the mixture to treated to a high pressure,

rtion of the'totalvolume of cooling and partially expandingthis portion by throttling to an intermedlate pressure, separating the liquid formed from the aseous portion, compressing the balance 0 the gaseous mixture to the intermediate pressure, cooling it, partially expanding it with the above separated gaseous portion with eous portions to liquefaction and reoti 'tion and using the above separated liquid 10 for this rectification. I

In testimony whereof I affiri my signature.

JEAN LE RoUE.