US2789946A

US2789946A - Thermal diffusion apparatus

Info

Publication number: US2789946A
Application number: US437549A
Authority: US
Inventors: John W Thomas
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1953-08-12
Filing date: 1954-06-17
Publication date: 1957-04-23
Anticipated expiration: 1974-04-23

Description

April 23, 1957 J. w. THOMAS THERMAL DIFFUSION APPARATUS Original Filed ,Aug. 12, 1953 INVENTOR. JOHN. W. THOMIIS WQQM HTTORNE Y5 2,789,946 r THERMAL DIFFUSION APPARATUS John W. Thomas, Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Original application August 12, 1953, Serial No. 373,807. Divided and this application June 17, 1954, Serial No. 437,549 1 3 Claims. (Cl. 210-176) The present invention relates to apparatus for the separation or concentration of fluids by thermal diffusion and more particularly to constructions designed to compensate for the difference in thermal expansion and contraction of the wall members of such apparatus and to facilitate their assembly.

This application is a division of application Serial No. 373,807, filed August 12, 1953.

.111 subjecting fluids, i. e., mixtures of materials that are gaseous or liquid under the conditions of operation or liquids containing one or more components dissolved or suspended therein, to thermal diffusion for the purpose of separating the components thereof or obtaining fractions containing concentrations of one or more of the components that vary from those present in the original fluid, the fluid is passed through or confined within a thermal dilfusion separation chamber defined by closely and substantially equidistantly spaced surfaces, one of which is maintained at a relatively higher temperature than the other in order to impose a temperature gradient across the chamber. The width of the chamber, i. e., the spacing between the chamber-forming surfaces, is of the order of about 0.15 inch or less, preferably less than about 0.06 or 0.08 inch in apparatus designed to subject liquids to thermal diffusion. For the thermal diffusion of gaseous mixtures, the width of the chamber may be considerably greater but is still preferably of the order of a small fraction of an inch.

The construction and assembly of thermal diffusion apparatus meeting these requirements has heretofore been attended with considerably difficulty, particularly where the apparatus comprises a considerable number of flat wall members, the exterior surfaces of which form a series of thermal diffusion separation chambers when they are bolted together with gaskets disposed between them. One of these difliculties has been due to the fact that when the apparatus is assembled, all of the wallmembers are at approximately room temperature, and when the apparatus is placed in operation, one of the wall members,

tus is assembled in the vertical position, considerable difficulty has also been experienced in maintaining the gaskets in their proper position until sufiicient pressure is applied thereto by adjacent wall members.

Similar difficulties have been encountered in the concentric tube type of thermal diffusion apparatus. In view of the extremely small width of the thermal diffusion chamber, it is manifest that it is almost impossible to provide a cylindrical gasket which at one and the same time will have a sufficient wall thickness and compressibility to facilitate insertion into the ends of the annular space between two concentric tubes, and once having been inserted, exert sufficient pressure against the inner surface of the outer tube and the outer surface of the inner tube to provide a seal that is leakproof when the temperature conditions vary between conditions of equal temperature of both tubes and relatively high and low temperatures of the inner and outer tubes, respectively, or vice versa, during operation. This difficulty is further aggravated by the fact that when a temperature gradient is applied across the annular separation chamber, i. e., when one of the tubes is heated to a temperature considerably higher than the other, the relatively highly heated tube will expand and thus give rise to leakage of fluids in the chamber past the gasket unless the gasket is prefabricated and fitted with extreme accuracy.

The present invention is directed to constructions designed to obviate these problems.

In accordance with the present invention, thermal diffusion apparatus is provided which comprises two or more wall members subject to difierential thermal expansion and contraction and having closely and substantially equidistantly spaced surfaces that define one or more thermal difiusion separation chambers. One or more gaskets are disposed between and in contact withportions of the wall members to confine fluid within the chamber or chambers. The gasket-contacting portion or portions of one or more of the wall members are inclined at an obtuse angle to the chamber-defining surface or surfaces thereof. The gasket-contacting portion or portions may also be recessed to facilitate retention of the gasket or gaskets in the desired position or positions during assembly of the apparatus and also to compensate for dimensional changes in the wall members during operation and, to make possible the use of one or more gaskets hav ing a thickness considerably in excess of the spacing between the charnber-forming surfaces of the wall members.

The term recessed, as applied to a wall member herein, is intended to mean that the portion of the wall member referred to has an indentation in its surface which departs from the chamber-defining surface of said wall member. Thus, in accordance with the invention, the recess of a wall member having a plane chamber-defining surface is a surface portion at an obtuse angle to the plane of the chamber-defining surface, and the recess of a wallmember having a cylindrical chamber-defining surface is a conical surface portion, the mean diameter of whichis greater than the diameter of said cylindrical chamberdefining surface.

Where the wall members are flat and the chamber-defining surfaces are substantially parallel to one another, in accordance with the present invention, the gasket-contacting portion is recessed at an angle, preferably obtuse, to the surface thereof defining one side of the chamber. Where the gasket-contacting portion of a first wall member is recessed at an obtuse angle, the gasket-contacting portion of theadjacent wall member, i. e., the member having a surface defining the other side of the chamber, may be parallel to the recessed gasket-contacting portion of the first wall member, or substantially parallel to its own chamber-forming surface, I

Where apparatus comprises inner and outer wall members, the chamber-defining surfaces of which are cylindrical and concentric to form an annular separation chamber, the gasket-contacting portion of the outer wall member may be provided, at one or both ends, with a conical recess having a diameter greater than the diameter of its chamber-forming surface. The corresponding end or ends of the innerwall member may be of the same, diameter as the chamber-forming surface thereof, have Patented Apr. 23, 1957 The advantages and utility ofthe apparatusof the.

invention will" become further apparentfrom the following'detailed description madewith reference to the accompanying drawing wherein:

Figure 1 is a cross-sectional view in elevation through one preferred embodiment of-the apparatus of the inventiong Figure 2'is a similar view throughanother preferred embodiment of the invention;

Figures 3, 4 and-5 arefrag-mentary viewsof similar apparatus, on a somewhat larger'scale; illustrating severalof the alternative embodiments of the invention;

' Figurei6' is a-cross-sectional view inelevation of a tubutar: type. thermal diffusion apparatus employing the principles of the invention; and" Figures 7, Sand -9 are fragmentaryviews, on a somewhat larger scale,- illustrating several alternative embodiments of the invention illustrated in-Figureo;

The apparatus illustrated: in Figure 1 comprises two wall members IOi-and 11' having closely and substantially equidistantlyt-spaced

surfaces

12 and 14; defining a thermal diifusionseparation chamber. 16, and agasket 17 between andtin contact with the portions 1 9 and: 20 thereof. The wall! members are. provided with coilst21 or other suitable .meansfor maintaining-thesurfaces 12 andi14 at=different temperatures and one. or both. of the wall members areprovided with ports 22 for introducing the fluid.

' ln thistxcmbodiment the gasket-contacting portion 19 ofthe-walhmember ,isat,an cbtuse angle (180 0) to the chambenforming surface 12, and the gasket-contacting portion of the wall member 11 is substantially parallel to the'portion 19. The gasket 17 is substantially thickerthan the width of the separation chamber 16. It ispreferred, in this embodiment, that the wall member 10 be the wall member that is maintained at the relatively higher, temperature during operation of the thermal difiusionseparation chamber Iii-inasmuch assuch a choice involves amiuimumpossibility of leakage past the gasket 17 during operation or during any interruptions in operation. It is further preferred that the angle 9 bean angle having a tangent. equal or close to the ratio of the chamber thickness to the chamber width. If the. resiliency of the gasket is fairly large, the angle 6 may be varied overarrange greater than wouldvbe-p ossible if the gasket were not tooresilient, such as 150%.

To illustrate the manner in which this construction compensates, for;v the differential expansion and contraction of the

wall members

10 and 11, the contractionof the wall member 10 upon cooling from the operating temperature is,illustrated, on an exaggerated scale, by dashedlines 2i,ands26 which shows an increase in chamber thickness, lt willtbe noted that upon contraction of the walLmember 10, which shows an increase in chamber width, ,the gasket con=tacting portion 19 thereof will tend to creep inwardly along the surface of the gasket 17 rather. than to reduce the pressure thereon. This means that even with fluctuating temperatures the spacing between gasket; surfaces 191 and 20; will remain constant. Thegasketlogadnill, thereforc,.remain constant, thereby assuring a leakproof seal. In addition, the recessing of thergasketecontacting portion 20 of the wall member 11 assistsdnimaintaining the gasket 17 in the desired position-during assembly of the wall members into the posi- Lion-shown.

The embodiment illustrated in Figure 2 likewise comprises wall-members 10a. and 11a havingsurfaces forminga separation chamber 12a'and a gasket 17a. In thisembodiment the wall member-11a isrecessed at 2011 to form a gasket-contacting portion that is substantially parallel toitschamber-formingsurface-14a; The gasket contacting surface 19a of the wall member 10a is in substantially the same plane as its chamber-forming surface 12a.

In this embodiment it is prefcrred that the wall member 10a be the wall member that is maintained at a relatively higher temperaturethan-the-wall-member 11a for the. reason. that less. gasket-material makes. Contact with;

the portion,.19a of'ithe: relatively hot. wall: member 10a than with the recessed portion 20a of the wall member 11a and is, therefore, less subject to deterioration by heater totransfer of heat (through the gasket to the and wherein one wallmember is'recessed atanangle 9 that is obtuse to its surface formingtlheseparation chamber 16c, and the other- Willll member 100 is substantially plane the gasket-contacting portionthereof being inthe same plane with its chamberformingsurface 12c.

Figure-5 illustrates an embodiment similar to that of Figure 1 in which: the spacing='between-the recessed gasket-contacting portioniiid of the wall member 11:! and the ga-skeeoontacting portion 19d'of the=wall"member lfld, and therefore also the operative thickness of the gasket 17d, are substantially equalto the width of the chamber 16d: Whilethis embodiment does not have the advantage of utilizing a gasket substanti lly thicker than the-width of-the-chamber, it possesses all of the thermal expansion and contraction compensating features of the embodimentill-ustra-tedin Figure 1.

Figure 6' illustrates a \tubular type of thermaldiffusion apparatus comprising an'inner wall member 30; an-outer wall member 31,- the outer surface-32 of the inner member 30 and the inner surface 34 of the outer member 31- being concentric *and' forming anannularseparation chamber 36; The upper end of the outer member 31 is shown as having a co-nically recessed gasket-contact ing portion 37 for receiving a gasket 39, andthe inner member 30lis provided; at the corresponding end, witha radially protruding conical surface 40 thatis complementary to the recessed conical surface 37 of the outer member 31. At the lower end, the separation chamber 36' is sealed by a 'cylindric-aigasket 41 havinga' thickness approximately equal to the width of'the separation chamber 36. It is to bcunderstood, of course, that the apparatus illustrated in Figure 6- is furtherprovidedwith suitable ports; such as'shown at 42, for the introduction of a fluid into the separation chamber 36' and the removal therefrom of separated fractions, as well as with any desired means for maintainingthe chamberfonning surfaces 32'iand' 34- at different-temperatures to impose a [temperature gradient across the chamber.

In this embodiment of the-invention it will be apparent that it is necessary to provide for relative expansion and contraction of the

wall members

39 and 31 at only one end if the wall members are more or less rigidly joined at the other end. It will be apparent, for example,

[that if Figure 6- represents the relative positions of the In the construction illustrated sliding of the gasket-contacting portion 40 over the surface of the gasket 39 and to a minor extent in applying somewhat greater pressure to the gasket 39. In any event, the necessity of providing a gasket of such extremely small thickness as that of gasket 41 is avoided inasmuch as the thickness of the gasket 39 may be several times the width of the chamber 36.

Figures 7, 8 and 9 illustrate several alternative embodiments of the invention illustrated in Figure 6. In Figure 7 the construction of the outer wall member 31a is identical to that shown in Figure 6 but the inner wall member 30a lras a gasket-contacting surface 40a of the same diameter as: the chamber-forming surface 32a and the shape of the gasket 39a is correspondingly altered. In Figure 8 of the inner Wall member 300: is substantially similar to that illustrated in Figure 7 but the outer wall member 31a is provided with a cylindrical recess 37a designed to accommodate a cylindrical gasket 39b 'having a thickness substantially greater than the width of the annular separation chamber 36. In order to limit the upward movement of the

gasket material

39a and 39b as a result of the contraction of the outer tube 31, an annular ring 43 may be placed at the top of the inner (tube 30a.

In Figure 9, the outer wall member 3112 is substantially similar to that illustrated in Figure 8 and the inner wall member 3% is provided with a radially protruding cylindrical surface 40b having a diameter smaller than the diameter of the cylindrical recessed portion 37a of the outer wall member and a gasket 396 is interposed between the portions b and 37a of the members 30b and 31a, respectively.

It is to be understood, of course, that any :two of the embodiments illustrated in Figures 6, 7, 8 and 9 may be combined in a single apparatus. Thus, the structures shown in Figures 7 and 8 may replace the structure shown in the lower end of Figure 6, and the structures shown in Figures 7, 8 and 9 may replace the structure shown at the top of the apparatus in Figure 6.

It is further to be understood that innumerable modifications will at once become apparent to those skilled in the art upon reading this description. All such modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. Thermal diffusion apparatus comprising two wall members subject to differential thermal expansion and contraction and having closely and substantially equidistantly spaced surfaces defining a thermal diifusion separation chamber, said chamber defining wall surfaces being flat and substantially parallel to one another, and a gasket between and in contact with portions of said Wall members for confining fluid within said chamber, the gasket-contacting portion of one of the wall members being at an obtuse angle to the chamber-defining surface of said one of the wall members, at least a part of said gasket contacting portion of said one wall member being spaced from the gasket-contacting portion of the other wall member a greater distance than the spacing between said surfaces, said gasket having one side engaging said part of said gasket-contacting portion of said one wall rnember and another side of said gasket engaging the gasket-contacting portion of said other wall member.

2. Thermal difiusion apparatus comprising two wall members subject to differential thermal expansion and contraction and having closely and substantially equi distantly spaced surfaces defining a thermal diffusion separation chamber, said wall members and chamber defining wall surfaces there-of being concentric and form ing an annular separation chamber, and a gasket between and in contact with portions of said wall members for confining fluid within said chamber, the gasket-contacting portion of one of the wall members being substantially conical and disposed :at an obtuse angle to the chamberdefining surface of said one of the wall members, at least a part of said gasket-contacting portion of said one wall member being spaced from the gasket-contacting portion of the other wall member a greater distance than the spacing between said surfaces, said gasket having one side engaging said part of said gasket-contacting portion of said wall member and having another side engaging the gasket-contacting portion of said other wall member.

3. Thermal diffusion apparatus comprising two well members subject to diflerential thermal expansion and contraction and having closely and substantially equidistantly spaced surfaces defining a thermal diffusion separation chamber, and a gasket between and in contact with portions of said wall members for confining fluid within said chamber, the gasket-contacting portion of the wall member subject to the lower degree of thermal expansion and contraction being an obtuse angle to the chamber defining surface thereof, at least a part of said gasket-contacting portion of said one wall member being spaced from the gasket-contacting portion of the other wall member :a greater distance than the spacing between said surfaces, the gasket having one side engaging said part of said gasket-contacting portion of said one wall member and having another side engaging the gasketcon-tacting portion of said other wall member.

References Cited in the file of this patent UNITED STATES PATENTS 1,312,913 Krause Aug. 12, 1919 1,830,205 McLa-i-ne Nov. 3, 1931 1,901,581 Chamberlain Mar. 14, 1933 2,541,069 Jones et al. Feb. 13, 1951 2,550,027 Thompson Apr. 24, 1951

Claims

1. THERMAL DIFFUSION APPARATUS COMPRISING TWO WALL MEMBERS SUBJECT TO DIFFERENTIAL THERMAL EXPANSION AND CONTRACTION AND HAVING CLOSELY AND SUBSTANTIALLY EQUIDISTANTLY SPACED SURFACES DEFINING A THERMAL DIFFUSION SEPARATION CHAMBER, SAID CHAMBER-DEFINING WALL SURFACES BEING FLAT AND SUBSTANTIALLY PARALLEL TO ONE ANOTHER, AND A GASKET BETWEEN AND IN CONTACT WITH PORTIONS OF SAID WALL MEMBERS FOR CONFINING FLUID WITHIN SAID CHAMBER, THE GASKET-CONTACTING PORTION OF ONE OF THE WALL MEMBERS BEING AT AN OBTUSE ANGLE TO THE CHAMBER-DEFINING SURFACE OF SAID ONE OF THE WALL MEMBERS, AT LEAST A PART OF SAID GASKET CONTACTING PORTION OF SAID ONE WALL MEMBER BEING SPACED FROM THE GASKET-CONTACTING PORTION OF THE OTHER WALL MEMBER A GREATER DISTANCE THAN THE SPACING BETWEEN SAID SURFACES, SAID GASKET HAVING ONE SIDE ENGAGING SAID PART OF SAID GASKET-CONTACTING PORTION OF SAID ONE WALL MEMBER AND ANOTHER SIDE OF SAID GASKET ENGAGING THE GASKET-CONTACTING PORTION OF SAID OTHER WALL MEMBER.