US2893713A - Bubble cap assembly - Google Patents

Description

July 7, 1959 ABHALTMEIER I 2,893,713

BUBBLE CAP ASSEMBLY Filed April 10, 1956 2 Sheets-Sheet 1 SECTION A-B PM B12 INVENTOR. ALFRED HALME/ER ATTORNEj July 7, 19.59 A. HALTMEIER BUBBLE CAP ASSEMBLY 2 Sheets-Shet 2 Filed-April 10, 1956 cINVENTOR. ALFRED HALTME/E R ATTORNEKS' United States Patent BUBBLE CAP ASSEMBLY Application April 10, 1956, Serial No. 577,235. 6 Claims. (Cl. 261-114) This invention relates to a new, improved bubble cap assembly and is a continuation-in-part and consolidation of my copending applications Serial No. 388,874, filed October 28, 1953 and now abandoned and 469,491, filed November 17, 1954, and now abandoned.

Bubble cap assemblies for use on distillation column trays are well known.

The bubble caps are conventionally in the form of a cap member having a closed top and a cylindrical, dome- .like or bell-like shape. The bubble caps are positioned above openings in the distillation tray sothat gases or vapor passing through this opening are trapped in the cap and pass out through the lower edge or rim of the cap which may be provided with serrations, grooves, slits, ridges, or the like.-

In operation when the gas or vapor passes through a bubble cap of known structure, a certain quantity of the liquid on the tray is carried upward by the gas or vapor tothe next subsequent tray. The efficiency of the bubble cap is limited by the quantity of this liquid carried upward which increases with an increasing gas'or vapor velocity. The decrease in the efiiciency with the increasing gas or vapor velocity is expressed by the so-called power amplification ratio as set forth in Kirschbaum DestillierundRektifiziertechnik, Edition II, page 242.

In order to increase the efliciency of operation, particularly when using higher gas or vapor velocities, it was proposed to insert baffle plates or pack layers 'offilling material between the plates or trays of the distillation column; Liquid carried along by the vapor is separated by these plates or packed layers, allowing the use of higher gas orvapor velocities without a decrease in efliciency caused by the carrying along of the liquid and thus a higher load.

These baffle plates or packed layers, however, have a certain space requirement which ofl-sets their advantage in that the same cause a decrease in the number of trays or plateswhich may be positioned in a given column height.

'One object of this invention-is a bubble cap assembly which overcomes the above mentioned disadvantages by preventing liquid from being carried-along by the upwardly moving gas or vapor in spite of a high gasor'vapor velocity andwithout the use of separating devices such as baflleplates or packed layers. This, and still further objects, will become apparent from the following description read in conjunction with the drawings in which:

Figurel is a vertical section of an embodiment of a bubble cap assembly in accordance with the invention,

Figure 2 is across-section of the embodiment shown in Figure Figure '3 is a perspective view of the bubblecap of the bubble capw assemblyvas shown. in Figure 1,

.Figure 4 is apartial vertical section showing an embodi- ;ment of a helical guide vane construction in accordance with the invention,

Figure 5 is a partial vertical section showing a still Patented July 7,. 1959 further embodiment of a helical guide vane for a bubble cap assembly in accordance with the invention,

Figure 6 is. a verticalsection of a still further embodiment of a bubble cap assembly in accordance with the invention provided with a deflecting ring,.

Figure 7 is a partial plan view of the embodiment shown in Figure 6,

Figure 8v is a vertical section of a still further embodiment of a bubble cap assembly in accordance with the invention provided with a deflecting. ring.

\Figure 9 is a partial plan view of the embodiment shown in Figure .8 and,

Figures 10, 11 and 12 are vertical sections showing still further embodiments ofbubble cap assemblies in accordance with the invention.

The. bubble cap assembly, inaccordance with the invention for use on a distilling column tray, has a bubble cap of conventional construction and a guide ring concentrically positioned about the bubble-cap,. defining. a turbulence chamber, adapted to be tilled .with liquid surrounding. thebubble cap. 'Flow guide means are posit tionedfor deflecting gasses passing from underthe bubble cap into the turbulence chamber in a direction to cause rotation of the liquid in the turbulence chamber.

Very surprisingly and'unexpectedly, by providingthe turbulence chamber, which is filled with liquid and which surrounds the bubble cap and by passing the gases or vapors, which will be generally referred to herein as gases, into the turbulence chamber in such a manner that the liquid in the turbulence chamber is caused to rotate, the liquid will no longer be carried along by the upwardly moving. gas. stream andthe. efliciency of the unit will-be substantially increased. Theflow guide means positioned for deflecting gases passing under the bubble cap into the turbulence chamber may be any desired guide means and may, for example, be in the form of guide vanes provided at the loweredge of the bubble cap. The guide means are, however, preferably, guide vanes positioned adjacent the outer surface of the bubble cap extending is an oblique direction with respect to the bubble cap axis to admit gases passing .from under thevbubble cap obliquelyinto the turbulence. chamber. With this arrangement, the pressure loss of the gases involvedin efl ecting the rotating motion of the liquid in theturbulence chamber is particularly low, whereas the. same is relatively higher if the guidemeansare formed at the lower edge of the bubble cap as, for example, in the form of slits obliquely directed into the turbulence chamber.

The invention will be described in further detail with reference to the embodiments shown in the accompanying drawing.

Referring to the embodiment, as shown in Figure 1, 3 represents a distillation column tray or plate of conventional construction provided with the chimney 2. A strap or brace 5 is secured across the chimney near its top and holds the threaded bushing 6, centrally positioned in the chimney. A bubble cap 1 is mounted above the chimney by means of. the threaded spindle 4.which is screwed into the bushing 6.

Aguide ring 8 is concentrically positioned about the bubble cap defining a turbulence chamber 9 adapted to be filled with liquid surrounding. the bubble cap. The guide ring 8 is covered with adefiecting ring 13 provided with a central opening 12 though the guide ring may be open on top or have openings through the top in any desired manner. The guide ring 8 may be positioned with its lower rimv spaced from the tray 3 to allow the flow of liquid therebetween or may, as shown, be positioned directly on the tray 3 and provided with the openings or slits 14 so that liquid may enter the turbulence chamber 9 from the tray 3. 7

A multiple number of helical guide vanes 11 are mounted on the outer surface of the bubble cap 1 and extend in an oblique direction with respect to the axis of the bubble cap which extends in the direction of the spindle 4. t t t The helical guide vanes 11 are preferably designed so that the same have an angle of inclination with a plane extending normal to the axis of the bubble cap of less than 45 and preferably about 15 to 30. In other words, if the helical guide vanes 11 were to be considered analogous to the threads on a screw with the outer surface of the bubble cap 1 being considered analogous to the outer surface of the core of the screw, the guide vanes would have a pitch of less than 45 and preferably 15 to 30. about mm., preferably about 20 to 50 mm.

The lower edge of the bubble cap 1 around which the gas bubbles flow need not be serrated or provided with notches, but, as shown, may be in the form of a smooth rim.

In order to distribute the gasbubbles which bubble around this rim, it is preferable for the guide vanes 11 to be substantially equidistantly positioned around the outer surface of the bubble cap in the manner of threads on a multi-thread screw. Six or eight guide vanes may, for example, be distributed around the outer surface of the bubble cap in this manner. The guide vanes, as shown, extend below and above the upper edge of the The width of the vanes should be more than bubble cap. In operation, liquid is maintained on the upper surface of the tray 3 and flows through the openings 14 into the turbulence chamber 9. Gas is passed up through the chimney 2, is captured under the bubble cap 1 and flows around the lower edge 10 of the bubble cap 1 into the turbulence chamber 9. As the gas bubbles move upwardly from the edge 10 of the bubble cap, the same are forced to follow a spiral path between the helical guide vanes 11 causing the liquid present in the turbulence chamber 9 to circulate. The pressure loss of the gases involved in eflecting the rotation of the liquids is very low since the helical guide vanes admit the gases tangentially or obliquely into the turbulence chamber and consequently it is not necessary to impart a tangential or oblique motion to the gas entering the bubble cap assembly. Due to the rotation of the liquid in the turbulence chamber 9 it is possible to considerably increase the gas load of the bubble cap assembly since the droplets carried along will fly off tangently due to the rotary motion and will be collected by the guide ring 8. The gases then flow through the opening 12 to the next tray and the deflecting ring 13 aids in collecting any droplet which may be carried along. The deflecting ring 13 or a similar ring may be mounted in the upper edges of the guide vanes 11 projecting above the top of the bubble cap 1. The liquid circulating in the turbulence chamber 9 is ejected over the upper rim of the guide ring 8 passing around the edge of the opening 12 in the deflecting ring 13. Since the droplets which are carried along by the upwardly moving gas are separated by more or less centrifugal force, and since this force is increased with an increasing velocity of gas flow and the tendency to 1 carry along the droplets with an increased gas flow is compensated for.

In order to prevent the upwardly moving gases from leaving the helical path defined by the helical guide vanes 11, as for example by moving past the outer rim of these helical guide vanes, the outer edges of the vanes may be bent downwardly so that the guide vanes are more or less in the form of an inverted trough or channel as, for example, may be seen from Figures 4 and 5.

Even, however, with this downward bending of the outer rim of the helical guide vanes, it has been found that at higher gas velocities a portion of the gas may tend to travel beyond the helical guide vanes and their downwardly bent edges so that some of the gas will not contribute to the rotation of the liquid within-the turbulence chamber defined by the guide ring.

In accordance with a preferred embodiment of the invention, this is prevented by positioning the guide ring in contact with the outer edges of the helical guide vanes, or by providing a deflecting ring concentrically positioned with respect to the bubble cap to deflect gases passing under the bubble cap, upwardly against the lower side of the helical vanes.

In the embodiment, as shown in Figures 6 and 7, the construction is similar to that shown in Figure 1 except that the bubble cap 19 is mounted directly on the tray 20 by means of the base flange 25, and the slit like openings 22 are provided through which gases escape from the bubble cap into the turbulence chamber 23. The helical guide vanes 21 are in the form of inverted semi-circular channels and a deflecting ring 24 is concentrically positioned with respect to the bubble cap 19 being secured to the base flange 25 as, for example, by spot welding. The guide ring 26 is completely open at its upper end.

In operation, the gases which pass through the chimney 27 escape from the bubble cap 19 through the slots 22 and are deflected upwardly by the deflecting ring 24 so that the same are directed and guided against the lower side of the lower ring of helical guide vanes 21. Substantially all of the gas, therefore, contributes causing the rotary motion of the liquid in the turbulence chamber 23. In all other respects the operation is the same as described in connection with Figure 1.

An embodiment, as shown in Figures 8 and 9, corresponds to the construction and operation of that shown in Figure 6 except that the bubble cap 29 is dome-shaped, the guide ring 30 frusto-conically shaped and the lower, outer edges of the lower ring of helical guide vanes 31 is secured to the deflecting ring 32 as, for example, by spot welding.

In the embodiment, as shown in Figure 10, the deflecting ring 38 is mounted in position above the tray 39 by construction and operation is the same as described in connection with the previous embodiments. Parts 42, 43

and 44 correspond to parts previously designated 2, 15 and 16 respectively.

In the embodiment, as shown in Figure 11, the guide ring 45 is mounted on an inwardly turned flange 46 and the deflecting ring 47 is connected as, for example, by spot welding both the flange 46 and the outer edge of the lower group of helical guide vanes 49 so that the vanes 49, the bubble cap 50, the deflecting ring 47 and the flange 46 are all rigidly interconnected.

In the embodiment, as shown in Figure 12, the guide ring 54 serves a dual purpose, also acting as the deflecting ring since the same is positioned immediately adjacent the outer edges of the helical guide vanes 55 with the guide vanes secured thereto as, for example, by welding. The gas passes under the bubble cap, through the slots 56, and is forced to pass along the helical path defined by the guide vanes 55 since the outer limit of flow is confined by the guide ring 54. The parts 57 and 58 correguide ring so as to define a turbulence chamber for liquid surrounding the bubble cap and by providing the guide means so that the gases emerging from the bubble cap will cause a rotation of the liquid in the turbulence chamber and a centrifugal separation of the liquid from the 'gas against the walls of the turbulence chamber.

While the invention has been described in detail with reference to the specific embodiments shown, various changes and modifications will become apparent to the skilled artisan which fall within the spirit of the invention and the scope of the appended claims.

As used herein, and in the claims, the term oblique with respect to the admission of gases into the tuburlence chamber is intended to designate any direction which will form an angle with a radius of the turbulence chamber including a tangential admission and will thus tend to cause rotation of any liquid in the turbulence chamber.

I claim:

1. A bubble cap assembly for use on a distilling column tray comprising a bubble cap, a guide ring concentrically positoned about said bubble cap defining a turbulence chamber surrounding the bubble cap, at least one helical guide vane having a downwardly deflected outer rim positioned adjacent the outer surface of said bubble cap oblique with respect to the bubble cap axis to admit gases obliquely into the turbulence chamber and means concentrically positioned with respect to said bubble cap to deflect gases passing under said bubble cap upwardly against the lower side of said helical vane.

2. Bubble cap assembly according to claim 1 including a multiple number of helical guide vanes surrounding said bubble cap, each of said helical guide vanes having a downwardly deflected outer rim positioned adjacent the outer surface of the bubble cap oblique with respect to the bubble cap axis to admit gases obliquely into the turbulence chamber.

3. A bubble cap assembly, according to claim 2, in which said helical guide vanes are substantially equidistantly positioned around the outer surface of said bubble cap.

4. Bubble cap assembly according to claim 1 in which said means concentrically positioned with respect to said bubble cap is a deflecting ring connected to said helical guide vane.

5. Bubble cap assembly according to claim 1, in which said means concentrically positioned with respect to said bubble cap is a deflecting ring connected to said guide ring.

6. Bubble cap assembly according to claim 1, in which said guide ring defines said means concentrically positioned with respect to said bubble cap.

References Cited in the file of this patent UNITED STATES PATENTS 1,605,264 Millard Nov. 2, 1926 1,674,464 Burke June 19, 1928 1,776,032 Kobernik Sept. 16, 1930 1,821,619 Day Sept. 1, 1931 1,878,467 Clarke Sept. 20, 1932 2,205,284 Eckart June 18, 1940 2,600,710 Wade June 17, 1952 FOREIGN PATENTS 128,497 Austria May 25, 1932 149,392 Switzerland Nov. 16, 1931 629,086 Germany Apr. 22, 1936 936,031 Germany Dec. 1, 1955 1,085,607 France July 28, 1954

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