US2752042A - Liquid thermal diffusion port design - Google Patents

Description

J1me 1956 w. E. SCOVILL 2,752,042

LIQUID THERMAL DIFFUSION PORT DESIGN Filed Aug. 27, 1953 V 2 SheetsShcet 1 INVENTOR. q- E WfiRNE/Z E. 5cov/LL A TTORNE vs June 26, 1956 w. E. SCOVILL 2,752,042

LIQUID THERMAL DIFFUSION PORT DESIGN Filed Aug. 27, 1953 2 Sheets-Sheet 2 i -C- 55" y 57 IAIIIIIIIIIIIIIIIII.

IIII'IIII YIIIIIIIIIII INVENTOR. WqR/vm E. Scowu.

BY W,Wamm

United States Patent Office 2,752,042 Patented June 26, 1956 LIQUID THERMAL DIFFUSION PORT DESIGN Warner E. Scovill, Lakewood, Ohio, assignor to I he Standard Oil Company, Cleveland, Ohio, a corporation of Ohio Application August 27, 1953, Serial No. 376,927

3 Claims. (Cl. 210-525) The present invention relates to continuous thermal difiusion apparatus for separating fluid mixtures and, more particularly, to novel and improved apparatus for improving the flow of fluid mixtures in apparatuses of this type.

One type of thermal diffusion apparatus that has been proposed in recent years for the purpose of resolving fluid mixtures into two or more dissimilar fractions has consisted essentially of two stationary smooth walls of inert, heat conductive materials spaced relatively close to one another to form a separation chamber, referred to generally as a slit. In this type of thermal difiusion apparatus, inlets and outlets are provided, usually in the walls, for the continuous introduction of fluid into the separation chamber and the continuous withdrawal therefrom of two or more separated fractions.

One of the major problems in systems of this type involves the distribution of fluid flow through the slit. Previous experimentation in systems of this type indicates .that one of the primary causes of poor results achieved in the separation of fluid mixtures by thermal diflusion is caused primarily by poor distribution of fluid flow through the slit. For example, upon dismantling a thermal difiusion column of the center feed, countercurrent flow, vertical flat plate type, when the length of the slit was 5 ft., the breadth about 2 ft., and the slit width about 0.035 in., and wherein the liquid measure was introduced into the slit through a line of small holes in the surface of one of the plates, the holes being spaced about of an inch apart, and the dissimilar fractions were withdrawn through ports of identical construction located opposite ends of the slit, the surprising discovery was made that the surface of the hot wall between the inlet port and the withdrawal port at the top of the slit showed a series of very sharp, parallel and colored lines, each connecting one particular hole of the inlet port with one particular hole of the withdrawal port. A similar series of lines were found on the cold wall between the inlet port and the other withdrawal port indicating that the flow was not distributed over the breadth of the slit but was more or less direct between the holes. This indicated that although the efliciency of the column was already considerably higher than had heretofore been believed possible, apparently only a fraction of the breadth of the slit was being used effectively in the process.

It is an object of the invention, accordingly, to provide novel and improved apparatus for controlling the flow of fluid through a thermal diffusion column, in order to overcome the aforementioned disadvantages.

In accordance with the invention, it has now been found that it is possible to overcome this defect by providing liquid thermal diffusion apparatus with inlet and withdrawal ports at least one of which, preferably at least the inlet port, comprises an elongated groove in the face of the wall forming a reservoir, a passageway for liquid extending from and substantially co-extensive with the breadth of the groove and communicating with the groove and the slit formed between the thermal diffusion plates, and a conduit communicating with the groove to the exterior of the apparatus. To promote movement of the liquid between the inlet and withdrawal ports in the form of continuous films rather than in a series of parallel streams, the volumetric capacity of the reservoir forming part of each, or at least one, of the ports, constructed in accordance with the invention, is large in relation to the volumetric flow capacity of the passage from the reservoir to the slit. To assure substantially uniform flow from the reservoir into the slit, the pressure drop between the reservoir and the slit will be large as compared with the diflerence in pressure across the passageway along the breadth of the reservoir. Therefore, the flow of fluid across the passageway is expected to be substantially uniform along its entire breadth. This results in an increase in the efliciency of separation obtainable in a thermal diffusion apparatus of given dimensions.

For a more complete understanding of the invention, reference should be had to the following detailed description of an exemplary embodiment of the invention taken in conjunction with the figures of the drawing, in which:

Fig. 1 is a perspective view in cross-section of a novel and improved port design for thermal diffusion apparatus, in accordance with the invention;

Fig. 2 is a view in vertical section, taken along the line 22 in the direction of the arrows, of the apparatus of Fig. l; and

Fig. 3 is a cross-sectional view in elevation of a thermal diffusion apparatus provided with the improved port design of the invention.

In Figs. 1 and 2, there are shown two thermal diffusion plates 11 and 12, which are separated by a gasket 13 and spaced apart by a distance less than about 0.15 in. The wall 11 is provided with an elongated groove 14 forming a reservoir. The groove 14 is connected by a conduit 15 to a suitable source of feed or a receptacle for the product, externally positioned with relation to the thermal diffusion plates 11 and 12. A ledge 16 is formed along 'the line of the elongated groove 14 and is positioned in "such a manner with respect to the walls 17 and 19 of the plates 11 and 12 as to form a restricted passageway leading from the elongated groove 14 to a thermal diffusion slit 18 formed by the plates 11 and 12.

In order to more clearly understand the functioning of the improved port construction, in accordance with the invention, let us consider the illustrated port as an inlet port to the thermal diffusion slit 18. Feed will be forced under pressure at a predetermined rate of flow through the conduit 15 from a suitable source of feed (not shown) into the elongated groove 14, which acts as a reservoir. It will be obvious to those skilled in the art that the pressure at points spaced along the length of the elongated groove 14 at varying distances from the conduit 15 will have values differing in proportion to their respective distances from the conduit 15.

The feed from the reservoir formed by the elongated groove 14 must flow in the restricted passageway formed by the ledge 16 and the wall 17 of the plate 12 in order to reach the slit 18. The pressure drop between the reservoir 14 and the slit 18 will be large as compared with the difference in pressure along the breadth of the reservoir 14.

Thus, there is provided a novel and improved port construction, wherein the flow of fluid between the slit formed by the thermal diffusion plates and a port communicating with the slit is substantially uniform along the entire breadth of the connection between the port and the slit.

The apparatus illustrated in Fig. 3 comprises two opposed walls 20 and 21 forming between them a separation chamber or thermal diffusion slit 22. At the lower end of the apparatus there is a groove 24 in the wall 21 which is coextensive with the face of that wall and lies in a direction transverse to the vertical direction of flow of on either plate.

liquid within the slit 22. A passage 26 for liquid is connected with the groove 24 and communicates with the exterior of the apparatus. The wall 21 is provided with a ledge 27 that is coextensive with the groove 24 and is positioned between the slit 22 and the groove 24 to form with the wall 20 a restricted passageway between; the slit 22andthegroove24. Y V

The port construction illustrated in the-upper portion of Fig. '3 is'essentially similar except that the ledge 27a is in the wall 20 rather than the wall 21. The apparatus is appropriately sealed by means of gaskets 29. Intermediate the upper and lower ports there is an inlet port comprising a groove 30, passage 31 for communication to the exterior, and ledges 32 and 33. a

In operation, the wall 21 may, for example, be heated and the wall 20 may be maintained at a relatively lower perature by means of a suitable heating medium, the fraction tending to accumulate adjacent the hot wall will ascend along said wall, flow past the ledge 27a, be collected in the groove 24a and withdrawn through passage 26a, whereas the fraction tending to accumulate adjacent the cold wall 20 will descend, flow past the ledge 27, be collected in groove 24 and withdrawn through passage 26. I a a a It will be obvious that the above-disclosed embodiments are meant to be merely exemplary and are susceptible of modification and variation without departing from the spirit and scope of the invention. For example, the ledge 16 will perform its function equally well regardless of whether the disclosed structural configuration is utilized as an inlet or as a withdrawal port, or whether it is 40 formed integrally or separately from the plates or formed Therefore, it is deemed that the invention is not to'be limited except by the appended claims.

I claim:

1. Liquid thermal diffusion apparatus comprising two substantially parallel, liquid-impervious stationary walls, the opposed faces of which are smooth and spaced apart to form a substantially uniform narrow thermal diffusion slit, means providing ports communicating with the slit through which the liquid is introduced into and withdrawn from said slit, at least one of said ports including an elongated groove longitudinally disposed adjacent said slit and in the face of one of said walls, a passage for liquid connected with said elongated groove and communicating with the exterior ofthe apparatus, .aledge in one of said walls running along the breadth of said elongated groove and positioned between said slit and said elongated groove and in such contiguous relationship with theother of said two stationary walls so as to form a restricted passageway between said elongated groove and said slit.

2. The apparatus described in claim 1, wherein said ledge is integral with said one of said walls' having said elongated groove therein. r g I p,

'3. Liquid thermal difiusion apparatus comprising two liquid impervious walls, the opposed faces of which are substantially equidistantly spaced apart to form a narrow thermal diffusion slit, and means providing ports communicating with the slit for introducing and withdrawing liquid into and from the slit, respectively, whereinat least one of said ports includes a groove in the face of one of the walls, said groove being substantially coextensive with said face and in a direction transverse to the direction of flow of liquid within the slit, a passage for liquid connected with said groove and communicating with the exterior of the apparatus, a ledge in one of said Walls coextensive with said groove and positioned between said slit and said groove and in such contiguous relationship with the other of said walls so as to form a restricted passageway between said elongated groove and said slit.

References Cited in the file of this patent UNITED STATES PATENTS Debye Sept. 11, 1951

Claims (1)

1. LIQUID THERMAL DIFFUSION APPARATUS COMPRISING TWO SUBSTANTIALLY PARALLEL, LIQUID-IMPERVIOUS STATIONARY WALLS, THE OPPOSED FACES OF WHICH ARE SMOOTH AND SPACED APART TO FORM A SUBSTANTIALLY UNIFORM NARROW THERMAL DIFFUSION SLIT, MEANS PROVIDING PORTS COMMUNICATING WITH THE SLIT THROUGH WHICH THE LIQUID IS INTRODUCES INTO AND WITHDRAWN FROM SAID SLIT, AT LEAST ONE OF SAID PORTS INCLUDING AN ELONGATED GROOVE LONGITUDINALLY DISPOSED ADJACENT SAID SLIT AND IN THE FACE OF ONE OF SAID WALLS, A PASSAGE FOR LIQUID CONNECTED WITH SAID ELONGATED GROOVE AND COMMUNICATING WITH THE EXTERIOR OF THE APPARATUS, A LEDGE IN ONE OF SAID WALLS RUNNING ALONG THE BREADTH OF SAID ELONGATED GROOVE AND POSITIONED BETWEEN SAID SLIT AND SAID ELONGATED GROOVE AND IN SUCH CONTIGUOUS RELATIONSHIP WITH THE OTHER OF SAID TWO STATIONARY WALLS SO AS TO FORM A RESTRICTED PASSAGEWAY BETWEEN SAID ELONGATED GROOVE AND SAID SLIT.

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