US2518746A - Bubble cap - Google Patents

Description

Aug. 15, 1950' C. L. BLOHM HAL BUBBLE CAP Filed June 14, 1948 M m W Hwm e mum m BM 9 4 EH sired state of division of the vapor.

Patented Alm UNITED STATE PATENT" OFFICE Clyde L. Blohnr Los and Ralph M.

Young, Long. Beach, Calif., assignors to The Fluor Corporation, Ltd.

corporation of California Los Angeles, Calii'., a

Application June 14, 1948, Serial N8. 32,944

1 claim. (or 261-114) This invention has to do with improvements in bubble caps of the type used for efiecting intimate liquid and gas or vapor contact on the trays of fractionating columns, absorbers, stills and the like.

As commonly formed, a bubble cap is shaped to be positioned over a so-called vapor neck extending above the surface of a plate or tray, and through which the rising vapor enters the cap and is diverted downwardly to be bubbled up through the tray liquid as the gas escapes past a submerged portion or edge of the cap. The most prevalent practice is to form the cap with bottom edge serrations or teeth which serve to divide the vapor into small streams which promote intimacy of contact between the vapor and liquid to a degree depending upon the extent to which the vapor is divided. Since the ultimate objective of the tray function is to achieve maximum intimacy of vapor and liquid contact, the tray emciency will be increased in proportion to increasing division of the gas and uniformity of its distribution throughout the liquid.

Our primary object is to provide an improved bubble cap characterized by its capacity for requiring extremely fine division of the vapor stream as it passes through the wall of the cap outwardly into the vapor stream. In accordance with the invention, the submerged skirt portion of the cap is formed of a finely porous material through which the vapor passes in such extremely divided streams as to form correspondingly small or minute bubbles in the liquid, thereby closely approaching a maximum of surface contact between the two phases.

The porous material preferably comprises a mass of finely divided particles bonded by incipient fusion at their boundaries so that the mass has fine and uniform porosity. The pore sizes may of course be predetermined by proper selection of the sizes of the fused particles, and the thickness or vapor passing dimension of the material may be determined to avoid excessive resistance or pressure drop, consistent with the detive we may employ a sintered metallic material of the type currently produced by the Micro Metallic Company of Brooklyn, New York, composed of sintered masses of powdered metals or alloys such as stainless steel, nickel-copper, nickel-silicon, bronze, copper-silicon, pure nickel, copper or iron, any of which may be selected in accordance with the properties of the liquid or gas to be contacted. For present purposes, we preferably As illustra- 2 employ such sintered material having an average pore size between 50 and 300 microns.

The invention will be more fully understood from'the followin detailed description of certain illustrative embodiments shown by the accompanying drawing in which:

Fig. 1 is a sectional view illustrating the hubble cap carried on a tray over the vapor neck;

Figs. 2 and-3'are sectional views of the cap illustrating different forms of bonds between the head and skirt portions of the cap; and

Fig. 4 illustrates a further variational form of the invention as embodied in a cap composed entirely of the sintered material.

Referring first to Fig. 1, the conventional bubble tray or plate l0 carries the usual vapor neck ll through which rising vapors enter the bubble cap, generally indicated at l2, to be directed thereby downwardly and outwardly into the liquid l3 carried on the tray. It is to be understood that the vapor neck II and cap I2 may be given any suitable shape and dimension, so long as the cap has a skirt portion submerged in the tray liquid and positioned to disperse the 'vapor in finely divided streams into the liquid, all as will presently appear.

According to the forms of the invention shown in Figs. 1 to 3, cap [2 comprises a closed top portion It formed preferably of a non-porous metal, and a continuous skirt portion l5 composed of the sintered and uniformly porous material referred to in the foregoing. The bottom edge l6 of the skirt may be spaced above the surface of the tray H), by bottom projections or feet I! which may be proportioned to give any desired bottom clearance between the cap and tray surface.

-The top and skirt portions of the cap may be formed and integrated or joined together in any suitable manner, as by stamping or casting the top portion I4 and bonding the preformed skirt portion l5 thereto by a fused joint as indicated by the weld [8 in Fig. 2. A mechanical interlock may be used according to the form of Fig. 3 by are closed by'impregnation with a pore sealing metal or other material, so that only the skirt portion 20a remains openly porous. The vapors entering the cap through the neck state of division of the vapors, the velocities of the streams passed by the individual. pores, and the complete uniformity with which the gas is dispersed from the cap periphery into the liquid. As will be understood, while sufllciently small to reduce the vapor to extremely finely divided streams, the pores in the cap skirt will be large enough to permit all the vapors to pass through the sintered material while maintaining a liquid seal inside the cap, preventing vapor escape from beneath its bottom I6.

Finally it may be observed that the present bubble cap presents a distinct advantage and improvement in attaining very uniform gas distribution throughout the tray liquid, despite wide range variations of vapor throughout.

We claim:

A bubble cap adapted to be placed over the vapor neck of a liquid and vapor contact tray, said cap comprising an impervious top portion and a skirt portion formed of material composed of a sintered mass of vfusible metal particles bonded together at their boundaries to form small uniformly distributed pores having an average size between about to 300 microns through which vapor passes from inside the cap in finely divided streams into the liquid on the tray, and a fused bond integrating said top portion with the porous skirt portions.

CLYDE L. BLOHM.

RALPH M. YOUNG.

REFERENCES CITED The following references are of .record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,824,836 Piggot Sept. 29, 1931 2,038,451 Schatteneck Apr. 21, 1936 2,070,067 Rice Feb. 9, 1937 2,294,973 Ford Sept; 8, 1942 2,428,889 Nutter Oct. 14, 1947

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