US1518255A - Art and apparatus for separating liquid gases - Google Patents

Description

Dec. 9,1924.

W. B. DODDS rART AND APPARATUS FOR SEPARATING LIQUID GASES Filed May 25, 1922 r patented Use.. 9% 1924o in-iran sra'ras rareur curi-uca;

l 'WVLLEM B. 'DODDS, OF JERSEY CITY, NEW JERSEY, ASSGNOR T0 SAFETY CAE HEATING 81: LIGHTING CUMPANY, A CORPORATIN 0F NEW JERSEY.,

AAlt'tl A 'ND APPRATUS FOR SEPARATING LIQUID GASES.,

Application led May 25, 1922. Serial No. 563,488,

To all 'whom t may concern."

Be it knownthat l, WILLIAM B. Donns, a citizen of the United States, and a resident of Jersey City, county of Hudson and State of New Jersey, have invented an lmprovement in the Art and Apparatus for Separating Liquid Gases.a of which the following is a` specification.

rllhis invention relates to the separation. of a gaseousfluid into its constituents and, more particularly, to apparatus and method for separating liquefied gases by evaporation and rectification into their respective constituents.

provide a simple and compact apparatus for effecting the separation of a liquefied gas into its respective constituents and to provide efficient apparatus of flexible control and operation for obtaining ases of a high degree of purity. Another o ject is to provide a practical method for obtaining gases of a high degree of purity and for insuring a positive control of the degree of purity of product desired. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction and operation, combinations of elements, arrangements of parts" and sequence and relation of steps which are exemplified in the'structure hereinafter described and the scope of the application of which willy be indicated in the following claims.

In the accompanying drawing in which is shown one of various possible embodiments of this invention,

" being preferably obtained from the heat of liquefaction of the fluid beingliqueied. lin thc ensuing description thefeatures of this invention will be described in connection particularly with the liquefaction of air and @ne of the objects of this invention is toY the subsequent evaporation thereof and rectification into oxygen and nitrogenc Referring now to the drawings there is shown a rectifying column taking the form preferably of a vertical container or c linder 10 provided` at its lower end witi an intake pipe 11 controlled by a valve 12 by means of which the flow of air preferably in gaseous form through the rectifying columnI may be'controlled. u v The apparatus is supplied with air under c pressure from, a manifold 18 in turn connected with a suitable source of supply. The air supplied to the manifold 13 preferably undergoes certain preliminary stages which may comprise first the compression of air from atmospheric pressure and at -room temperature. During this compression the temperature of the air is materially raised and the compressed air may be preliminarily cooled to a temperature somewhat below normal while maintaining the increased pressure resulting from the compressionn Suitable means Inay be employed tov purif or cleanse the air thus operated upon. hese preliminary steps are not illustratively set forth .in the drawing and it is obvious that they may be Varied or replaced .by other operations. The air under pressure thus supplied the manifold 13 passes preferabl through a heat-transferring device whicli may conveniently comprise a plurality of concentrically arranged cylindrical shells'14, 16 and 17 in spaced relation to form the'rebetween annular chambers 14-16 and 16-17 through which fluid may be passed. Within the chamber 14--16 formed by the two shells 14 and 16 is positioned a plurality of spirally woundcoils extendin throughout the length of the column and connected at their upper ends .to the manifold 13 thereby to permit the (passage through the coils 15 in a downwar direction of air under pressure supplied from the manifold. r1`he `lower' ends of the plurality of coils 15 discharge into the pipe 18 to which the pipe 11 with the controlling valve 12 interposed therein is connected, thus to supply the rectitfying column 10 with air under pressure and cooled bV th@ DSSg through the heat-transferring devlce.

- As conductive to a clear understanding of the functioning of the heat-transferring device above mentioned, it might at this point be noted that at the top of the rectifying column l there is provided a delivery or outlet pipe 19- through which the nitrogen or low boiling constituent is withdrawn and that the column is provided at its base with an outlet or delivery'pipe '2O through which the oxygen or high boiling constituent is adapted to be withdrawn. The pipe 19 is extended as at 19a`to the bottom of the heat interchanger chamber 14-16 so that the low boiling constituent withdrawn therethrough may be passed in counter current with respect to the `air under pressure in the tubes 15 through the chamber 14-l6, an outlet 21 at the upper end of the heaty interchanger chamber being provided for eventually withdrawin the low boiling constituent. The outlet pipe connected to the base of the column 10 is extended as at 2()a to the bottom of the heat interchanger chamber 16-17 through which the oxygen may be passed in an upward direction or in counter current relation with respect to the air in the tubes 15 through the heat interchan er, an outlet 22 being provided at the top o the heat interchanger chamber for subsequently withdrawing the oxygen or high boiling constituent. The products of rectification emanating from the rectifying column 10 are thus made to further reduce the temperature of the air supplied from the manifold 13 and, in effect, reduce its temperature materially below normal. p

From the pipe 18, thus supplied with low temperature air under pressure, air is permitted to discharge through the Valve 12 controlled by the handle 12, the valve 12 permittin the air to expand into the chamber 23 pos1tioned at the interior lower portion of the rectifying column 10. During its expansion the air is cooled to the point of liquefaction and is preferably only partly liquefied and to an extent suflicie'nt so that the heat of liquefaction given up by the air in the subsequent stages may be transferred to the air undergoing evaporation and rectification and to provide the latter with the heat of evaporation.

From the chamber. 23 the air passes through a distributing chamber 24 to which the lower ends of a plurality of heat interchangin coils 25 are connected, thus subdividing t 1e partially liquefied air into a plurality of relatively small streams. The coils 25 extend in an upward direction throughout substantially lthe entire extent of the container or column 10 and at their upper ends are connected to a collecting chamber 26.` During the passage of the air upwardly through the plurality .of coils 25 its liquefaction is substantially completed as will be more clear- 'ly hereinafter set forth, and from the collecting chamber 26 into which the individual coils 25 discharge a pipe 27 conducts the liquefied air to an expansion valve diagrammatically indicated at 28 and-controlled as by the handle 28. From the expansion valve 28 a pipe 29 leads the expanded fluid downwardly to the distributing pipes 30 from which the fluid .is discharged 1n a plurality of divergent streams and from which it is free to travel in a general downward direction through the rectifying column 10.

The spaces between lthe plurality of coils 25 and thecylinder l0 are filled with a lurality of relatively small particles 31, tfiese particles being of a material such as cop r, for example, having a high thermal condii tivity. The liquefied air expanded throu h the valve 28 passes downwardly throu l1 tilie column 10 and through the partie es 31 packed around the coils 25 and is subjected to a progressive evaporation and rectification. The plurality of particles 3l of high heat conductivity act to subdivide the downwardly moving fluid into .a large number of relatively small streams and thus act to insure intimate thermal contact between the upwardly moving fluid in the coils 25 and the downwardly moving fluid in the rectifying column l0. The high heat conductivity of the particles 31, furthermore, insures an efficient transfer of heat from the upwardly moving fluid in the coils 25 to the downwardly moving fluid in the column 10. The resulting interchange of heat, that is, the resulting'withdrawal of heat from the fluid in the coils 25, causes the completion of the liquefaction of the fluid in the coils 25 to take place and the heat thus absorbed by the downwardly moving fluid is effective to boil off the low boiling constituent or the nitrogen. The resultant temperatures assumed in the rectifying column 10 will be such that there exists' a progressively lower temperature as the fluid in the coils 25 moves toward the top, thus to complete the liquefaction thereof progressively, and .such that the downwardly moving fluid in the column l() meets with a progressively increasing tcmperature as it ap roaches the bottom of the column 10. The ownwardly moving fluid is thus subjected to progressive evaporation and rectification, that is, the low boilin constituent is first progressively boiled o the vapors resulting therefrom rising through the column 10 and being withdrawn through the pipe 19 at the top of the column and assed through the heat interchanger chamer 14-16 as hereinbefore described. As the fluid passes downwardly through the rectifying column 10 the low boiling constituent or the nitrogen is boiled ofi'A to a progressively greater degree and the downwardly moving fluid thus becomes progressively richer in its content of high boilin constituent or oxygen. The latter is co lected in the bottom of the column 10 lfrom which it may be withdrawn through the pipe 20 in gaseous or partly liquid form and passed upwardly throughl the heat interllll) lli changer chamber 16-17 to cool the incoming air as hereinbefore described.

The effective operation as hereinbefore described is materially dependent upon the maintenance at the base of the rectifying column lO'of a temperature limit for the temperature lgradientv throughout the column 10 sufficiently high to insure the progressive evaporation from the down-wardly moving fluid of the low boiling constituent; and a material lowering of this temperature limit existing at the base of the column 10 results in the retention in the collected Huid at the base of the column of-an undesirable quantity of low boiling constituent or nitrogen. The degree of purity of the high boiling constituent or the oxygen withdrawn from 'the base of the column is thus materially and detrimentally affected.

v In order, therefore, to insure a convenient control over this temperature limit there is positioned within the column 10 and extending throughout a substantial range of the lower portions ofv the column 10 what may be termed an auxiliary heat-transferring device taking `the form of the coil 32. The coil 32 has its lower end connected by means of the pipe 33, the valve 34 and the by-pass pipe 35 to the air-supplying manifold 13. The connection of the heating coil 32 therefore will be seen to be such that the air supplied thereto wil-l be by-passed around the heattransferring devices 14-16 and 16-17 throughfwhich the rectifying column is normally supplied with cooled air as hereinbefore described. The air supplied to the coil 32 and foy-passed around the heat-transfer- V ring devices is expanded at the valve 34 and just prior to its entry into the coil 32, thus resulting in a material lowering of the `temperature as a result of the expansion. The drop in pressure broughtabout by the valve 34 is preferably substantially the same as the drop in pressure resulting the valve 12 supplying the coils 25 of the rectifying column, but since the air expanded through the valve 34 is not previously cooled to a subnormal temperature the resultant temperature after expansion through the valve 34 will be relatively greaterthan the temperature of the expanded air entering the coils 25 in the rectifying column.

The' flow of this warmer air through the coil 32 may be so regulated that for given conditions of operation in the rectifying l column 10 tending to cause a too great lowerrnitrogen will ing of the temperature at the base 'of the column the air in the coil 32 may counteract this lowering in the temperature at the base of the column and may readjust andmaintain this temperature at the desired value at which the low boilingr constituent` or be substantially entirely evaporated o'r boiled off from the fluid collected in the base of the column. Thus the one temperature limit in the column 10 necessary for efficient action and 'for the attainment of a high degree of purity of hi h boiling constituent or of oxygen may be su stantially automatically maintained by adjusting the flow of the preliminarily uncooled air through the coil 32.

As the expanded and relatively warmer air passes through the coil 32 to prevent the over-lowering of the temperature at the base of the column the air becomes materially cooled due to the transfer of heat therefrom to the lower portions of the column and may be substantially liquefied due to such cooling thereof. The coil 32 extends preferably throughout a sufficient extentof the lower portion of the column 10 to bring abouta substantially uniform distribution 'throughout the lower portion in the column 10 of its temperature readjusting effec-t. end of the coil 32 is connected as by means of the pipes 36 Vto a convenient part of the apparatus where it may be subjected to ultimate evaporation and rectification together with the main flow of air through the apparatus. Thus, as shown in the drawings by way of illustration, the pipe 36 is connected to the collectingchamber 26 into which the heat-transferring coils 25 discharge vfrom whence the air as hereinbefore described is passed through theexpansion valve 28 and discharged into the rectifying column. Thus it will be seen that the temperature at the base of the column 10 is placed under positive control so that a high degree of purity of high boiling constituent or oxygen may be obtained and that such control by means of a secondary stream of air is efficiently carried out since the air after performing its controlling function is discharged into-the column for rectification so that no heat losses occur. The operation may thus be carried on at exceedingly high thermal efficiency.

It may at this point be noted that the air throu h the coil 32 may be allowed to pass theret rough continuously at the proper rate of flow or, if desired, may be passed therethrough intermittently and only at such times as the temperature at the base of the' column 10 has reached such a value as to affect-the degree of purity of oxygen obtained at the base of the column.

It will thus be seen that there has been provided in this invention a method and apparatus for the separation of a gaseous fluid into its constituents in whichthe sev- The uppereral objects hereinbefore set forth are achieved and' in which many advantages are attained. It may furthermore be noted that there has been provided a method and apparatus in which a positive control in the. operating conditions may be readily effected to insure the attainment and maintenance of conditions of operation best adapted for the attainment of a high degree of purity of product as well as of a high degree of eficiency.

As many possible embodiments might be made of the above invention and as many changes might be made -in embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.'

I claim:

1. The method of separating fluids which consists in cooling a gaseous fluid, passing the cooled fluid through successively colder` portions of-a heat-transferring device to liquefy it, evaporating and rectifying the liquefied fluid through successively warmer portions of said device by causing the evaporating fluid to absorb its latent heat of evaporation from the latent heat of liquefaction of the incoming fluid, whereby the constituent of said fluid having a low boiling point is evaporated first and withdrawn leaving fluid rich in the high boiling constituent to be withdrawn separately from said rst constituent, heating said fluid rich in high boiling constituent prior to withdrawal by means of gaseous fluid of higher temperature than said first-mentioned gaseous fluid whereby. said low boiling constituent in said fluid rich in high boiling constituent is evaporated and separated therefrom and whereby said uncooled fluid is reduced in temperature, and in evaporating and rectifying said cooled fluid through successively warmerportions of said heattransferring device.

2. The method of separating fluids which consists in coolinga gaseous fluid, passing the cooled fluid through successively .colder portions of a heat-transferring device to liquefy it, evaporating and rectifyingthe liquefied fluid through successively warmer portions of said device by 'causing the evaporating fluid to absorb i'ts latent heat of evaporation from the latent heat ofv liquef'action of the incoming fluid whereby the constituent of said` fluid having a low boiling point is evaporated first leaving a fluid rich in the high boiling constituent, withdrawing the evaporated low boiling constituent at a relatively cold point in said device, collectin for subsequent withdrawal at a relative y' warm point in said .device said fluid rich in high boilin constituent, maintaining said collected. uid at a temperature substantially above the boiling point of said low boiling constituent by separatel passing therethrough uncooled Huid where y said low boiling constituent in said collected fluid is substantially entirel boiled ofl' to leave the constituentl ofy higi boiling point, and in withdrawing said constituent of high boiling point.

3. The method of separating fluidsy which consists in cooling a gaseous fluid, passing the cooled fluid through successively colder` portions of a heat-transferring device to liquefy it, evaporating and rectifying the liquefied fluidl through successively warmer portions of said device by causing the evaporating fluid to absorb its latent heat of evaporation from the latent heat of liquefaction of the incoming fluid whereby the constituent of said fluid having a low boiling point is evaporated first leaving a fluid rich in the high boiling constituent, withdrawing the evaporated low boiling constituent at a relatively cold point in said device, collecting for subsequent withdrawal at a relatively warm point in said device said fluid rich in high boiling constituent, preventing said heat-transferring device from attaining at such collecting point a temperature materially lower than that of the boiling point of-said low boiling constituent by passing separately through said collecting point of said device uncooled fluid whereby said low boiling constituent in said collecting fluid is substantially entirely boiled ofi' and whereby Said uncooled fluid is reduced in temperature, and subjecting the 'fluid thus reduced in temperature to evaporation and rectification in said heattransferring device.

4. The method of separating fluids which consists in cooling a gaseous fluid through a first heat-transferring device, passing the cooled fluid through successively colder portions of a second heat-transferring device to liquefy it, passing the liquefied fluid through successively warmer portions of Said second device to evaporate and rectify the liquefied fluid whereby the constituent of said fluid having a low boiling point is evaporated first and withdrawn leaving a fluid rich in the high boiling constituent, collecting said fluid rich `in high boiling constituent in a relatively warm portion of said second device, passing gaseous fluid around said first heat-transferring device and separately through said collected fluid rich in high boilingc'onstituent whereby the low boiling constituent in said collected fluid is substantially entirely boiled off and whereby said by-passed fluid is reduced in temperature, and evaporating and rectifying said by-passed fluid through successively warmer portions of said second heat-transferring device.

5. VThe method of separating fluids which consists in cooling a gaseous fluid by passing it through a first heat-transferring device, passing the cooled fluid through successively colder portions of a second heat-transferring device to liquefy it. evaporating and rectifying the liquefied fluid through successively warmer portions of said second device whereby the constituent of said fluid having a low boiling point is evaporated lli Maaate first and withdrawn leaving Huid rich in the high boiling constituent, collecting for subsequent withdrawal at a relatively warm portion in said second device said fluid rich in high boiling constituent, by-passing gaseous fluid around said first heat-transferring device and separately through said fluid rich in high boilingl constituent whereby the low boiling constituent in said collected fluid is evaporated and separated therefrom and whereby said by-passed fluid is reduced in temperature, subjecting said by-passed cooled duid to evaporation and rectification in said second heat-transferring device, and in passing one of the constituents of rectification withdrawn from said second heattransferring device through said first heattransferring device. r

6. lin apparatusof the class described, in combination, aheat-transferring device comprising successive portions maintained at progressively varying temperatures, means for passing through successively warmer portions of said device a liquefied fluid for evaporating and rectifying said fluid whereby the constituent of said fluid having a low boiling point is evaporated first leaving fluid rich in the high boiling constituent, means for withdrawing said evaporated low boiling constituent, means for collecting said duid rich in high boiling constituent, auX- iliary means for heating said collected fluid to boil od the low boiling constituent contained therein, and means for withdrawing from said collecting means the high boiling constituent. Y

7. ln apparatus of the classdescribed, in

p combination, aheat-transferring device comprising successive portions maintained at progressively varying temperatures, means for passing through successively warmer portions of said device a liquefied fluid whereby the constituent of said duid having a low boiling point is progressively evaporated through said successively warmer portions of said device leaving fluid progressively richer in the high boiling constituent as said evaporating duid approaches the warmer portions of said device, means for collecting at a relatively warm portion of said device said fluid rich in high boiling constituentaux iliarylheat transferring means positioned in'. said warmer portion. of said heat-transferring device for maintaining said portion ofv said device and said collected fluid at a ternperature materially above the boiling point of said low boilingconstituent, means for withdrawing said evaporated low boiling constituent, means for withdrawing said collected uid, means for passgthrough said May, ieee..

auxiliary heat-transferring means gaseous fluid, and means for discharging said fluid from said auxiliary heat-transferring means to said heat-transferring device for evaporation and rectification.

8. In apparatus of the class described, in combination, a heat-transferring device for cooling a gaseous fluid, a second heat-trans ferring device maintained at progressively varying temperatures for liquefying the fluid, means for passing the liquefied fluid through successively warmer portions of said second heat-transferring device to evaporate and rectify first the low boiling constituent thereof and to leave fluid rich in high boiling constituent, means for collecting said fluid richin high boiling constituent at a. relatively Warm portion of said second heat-transferring device, a third heattransferring device associated with the relatively warm portion of said second heattransferring device, means for passing gaseous fluid around said first heat-transferring device and through said third heattransferring device whereby the low boiling S5 constituent 'in said collected fluid is substantially entirely boiled ed 'and whereby said fluid passing through said third heat-trans ferring device is reduced in temperature, and means for discharging said fluid from said third heat-transferring device to said second heat-transferring -devicefor eva-poration and rectification.

' 9. lin apparatus of the class described, in combination, a heat-transferring device for cooling a gaseous fluid, coils maintained at progressively varying temperatures adapted for the passage therethrough of said cooled fluid to liquefy it, a container surrounding said coils and providing a channel for the passage of fluid Within the container and outside of said coils and in thermal contact with said coils, means for discharging said liquefied fluid from said coils through progressively warmer portions of said channel whereby the low boiling constituent of said Huid is evaporated and rectified first and whereby fluid rich in high boiling constituent is adapt-ed to collect in said container and at a relatively warm portion thereof, a coil positioned within said container and substantiallyv at the warm portion of said channel vformed thereby for heating said collected Huid and for boiling ed` the low boiling constituent thereof, and means for passing through said coil uncooledduid.

lin testimony whereof, ll have sied my name'Y to this specification this 9th day of lllltl

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