US1736070A - Method of absorption - Google Patents

Description

NOV. 19, 1929, J, ,oh-CAMPBELL 1,736,070

METHOD '0F ABSORPTION original Filed July so, 1925 2 Sheets-sheet 1 GAS i291. y j? 2 i y, Y

3g 36 30 c x Nov. 19, l 929. J. A. CAMPBELL l METHOD oF ABsoRPTIoN 1925 2 Smets-sheet original Filed July :50

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Patented Nov, i9, i929 sr Tes JULIAN A'. CAMPBELL, OF LONG BEACH, CALIFORNIA METHOD or ABsonPTIoN original applications serial No. 46,974, mea .Tiny-ao, 19a5, and serial no.' 79,073, area January 4, 192e.

Divided and this application led April 19, 1927. Serial No. 184,870.

This application is divisional of my application Serial Number 46,974, filed July 30, 1925, entitled Absorber, now Patent No. 1,654,785, issued Jan. 3, 1928, and a division 5 of my application Serial No.V 79,073, filed Januar 4, 1926, on Absorber, and since issued, Sept. 27, 1927, No. 1,643,696. In this application the subject matterof the inven-A tion relates to a method foi` causing certain relative flow and inter-contact of gases and liquids; leaving in said prior application Serial No. 46,974, the claims upon the structural features having relation to support, assembly, etc. For that reason the feature relating purely 1to structure will not be dc scribed in detail in this application.

This invention has to do with methods of 4the general character variously known as absorption methods or.systems; the purpose of such methods being to 4intimately distribute and admix a .gas or vapor with a liquid, so as to get intimate nely divided contactbetween the gas and liquid. Sometimes thesev methods are used for the purpose zof loading a gas or vapor with substances that theyvmay pick up from the liquid by refason of their intimate contact'therewith. Thus although the present method is termed an" bsorption method and has been devel- 3o oped' more particularly for use as such, and

i particularly for absorbing the vapors of volatile hydrocarbons such as gasoline from casing head gas andthe like, itwill be understood that the inventionv is not thereby limited V-ftofsuch use. d A `description of an illustrative apparatus'and` its operation'for carrying out the inventionispecifically asa method of absorption will make it plain to all those skilled ,in-1` the. art how the method may be used `forfo.th er purposes.` y

VAlthough vthe general structure and details of apparatusv hereinafter particularly de'- scribedare but` illustrative and indicative of atypical apparatus for carrying out the method embodying the invention, I'give a 'detailed and specific description of thepreferred and specific form of device shown in the'aceompanying drawings so that others -may have a full understanding of the invention; it not being intended that the method be limited to use in the particularl apparatus hereinafter described. For the purpose of such description, I now refer to the accompanying drawings, in which:

Fig. 1 is an exterior elevation, parts being broken away, showing a form of my ini'- proved absorber;

Fig. 2 is an enlarged horizontal section on line 2-2 ofFig. 1;

' Fig. 3 is an enlarged horizontal section on line 3 3 of Fig. 1;

Fig. 4 is an enlarged vertical section of the lower part of the absorber showing the relativ arrangements of its various elements; an

Fig. 5 is an enlargement in detail of cer tain portions of Fig. 4.

The absorber is preferably housed within a tower-like shell or casing 10 constructed of any suitable material, preferably of sheet or plate metal. Vithin this tower there is a number of superimposed perforated floors 11. Each of these floors is formed of a suitable `plate perforated with a large number of comparatively small openings, so that the gas iiowing up through the floors is broken up into fine streams.. And these openings are of such a size that gas pressure beneath the floor will prevent flow of vliquid downwardly through the perforations.

The structure for supporting these fioors and Yfor making fluid-tight joints' between them and shell 10 is the particular subject lmatter of 'my issued Patent No. 1,654,785 and, therefore, willi not be describedhere; except that I say that, as indicated at 12, means are provided at the periphery of each floorfor making a Huid-tight joint with the shell, and that the ioors are supported on suitable columns or posts 13 Vthat extend vertically through the several floors. It will suffice hereto say that the several floors are rigidly supported in vertically spaced relation, are supported so as to be accurately level and so that the overflow pans attached to each floor are accurately in level.

Each' floor, as I have said, is formed of a perforated plate; and each floorcarries a plurality of overflow pans 30 supported on tubes 31 that pass through the floor and enioe i tend to a point near' the-Hoor next, below. .p

y VPans 30 are carried at a suitable height above ing liquid traps through which the gas cantheir corresponding loors,the height depending somewhat upon various conditions, including the character or 'consistency of the' absorbing-liquidi- I-t is the function of these pans to takeoverflow from the'froth that` forms over each'fioor,y and 'theirvheightmay be somewhat varied in4 order to make them properly perform their functions:A Tubes 3l maybe supported in floors -1l by flange connections 32; andat their lower lends these tubes have spreader cones 33 that lie close to the floor below; the lower ends of the tubes being at points near .enough the floor below that they are always submerged by the liquid or liquid and froth on that floor. The column of liquids in the tubes during operation prevents passage of gas directly up through the tubes.

The tubes 3lof pans 30 associated with the lowermost floor 1l, instead of having spreaders, have on their lower'ends-cups 34 formnotfpass upwardly. By reference to Figs'. 2 vand 3 it will be seen that each floor carries a plurality of overflow pans 30 and that the arrangement-on alternating floorsis made so that the lower ends of tubes 3l from the Hoor above are spaced between' the pans 3() on the. next floor below. The pans 30 are made of considerable area,l and are preferably relatively shallow.

The absorbing liquid-in a typical case, a fairly heavy petroleum oil-is yfed into the apparatus through pipe and is distributed to the uppermost floor ll by a perforated pipe 36. Flowing over this uppermost floor the liquid is prevented from flowing directly through the floor perforations by reason of the gas pressure beneath the floor. The gas isiinitially introduced at 37 below the lower- `most floor ll and at a point above the liquid outlet 38, so that gas is introduced above the' liquid level standing inA the bottom of the shell. The gas, under suitable pressure, passes upwardly through the perforations in the lowe'inost floor andbubbling up 4in finely divided streams, and therefore in fine bubbles through the liquid on that floor, creates a considerable froth which standson the surface of whatever clear liquid there may be present. This froth is constantly breaking up and releasing the gas into the space above, the gas being thus released to pass under pressure through the next floor up. At each Hoor the same kind of action takes place until the gas passes through the uppermost fioor, when it finally passes ofi' through the gas outlet 39. f

At each floor .a mass of froth is formed; fine bubbles being formed by formation of a film of oil around each minute gas bubble. This finely divided froth blows up in each floor until it reaches thev level ofthe upper edges of pans 30; and the uppermost part of v paratus the .metal strip to circular form and securing its ends the froth then overflows constantlyinto the pans. It is the uppermost partsof the froth .uppermost part, which flows over -the edges o the pans and-inte fthe pans, breaks up, releases the entrained gas, and,- inthe form g of vclear 'liquid,j flows from the pans through tubes 3land'thus down onto the next floor. .AsI I have said before, the lower ends of tubes 3l are close enough to the next floor and submerged in-the froth, and hold a column of liquid so that the; gas cannot flow'upwardly through the tubes. Thel gas is thus constantly being bubbled in Very `fine division through the liquid at each floor, a fine froth is vconstantly being formed, giving exv4,tremelyintimate contact between the liquid andv gas orl vapor, the froth .is constantly breaking up and the resultant liquid from the broken up froth is constantly flowing from one floor to they next. y Whilethe liquid is thus slowly flowing downwardly through the ap- The capacity of the apparatus is governed mainly by its area in plan; the length of time during which the gas or vapor is in intimate contact with the liquid-and therefore the thoroughness with which. absorption or-other interchange betweenthe gas and liquid takes place-is governed at least in part by the gas is passing upwardly through number of superimposed floors in the apparatus. However, it will beunderstood that in a structure of given size, the gas or vaporl is in my apparatus p ut into much more intimate contact and kept in that contact during a much longer time period than is true in ordinary forms of absorption apparatus.

There are several features t'owhich I wish particularly to call attention, these features having to do with the high efficiency obtained in my absorber. Considering Fig. 5, the froth level is there shown at L, this level being usually slightly above the peripheral edges of pans 30. I have found that a most edective breaking up ofthe froth and flow of I comparatively clear liquid over the pan edges is obtained when the'pan edges are left in` what is known as the raw state. These .pans are, in practice, made by cutting or shearing a strip'of comparatively thin sheet (about-#16 gauge), bending that together to form a side wall, and thensecuring 'the circular side wall to a bottom plate. In thus making the pans I leave the upper sharp raw edge I iind to be very effective-in breaking up the froth at the pan edge; so that practically nothing but clear liquid flows intoA each pan and thus flows down through tube to the next level. .Y

"When this liquid reaches the next level it is spread out over the next floor ll bythe spread A er con-es 33. lt will be noted that these spread er cones are so placed and formed that they throw the liquid outwardly and cause it to more outwardly over the floor l1: and inimediately upon striking the floor this liquid begins to be picked up by the gas that flows through the pertoratious, being thus intim mately interniingled with the gas and again VVformed into froth. Spi-ea ding cone 33 spreads the liquid flow out into a co'uiparati'i'ely thin sheet or lilin; and this fact tends to increase the intimacy of vcontact between the gas and liquid. But it will be noted that the liquid flowing down through tubes 3l and spread by cones 33 is not thereby thrown upwardly, but is only thrown outwardly; that its flow niotion is only'outwardly over the floor under the mass of froth and that, in order to move upwardly, this liquid must be picked up by the up yardly flowing gas and therefore can only be moved upwardly as froth. The froth is therefore initially formed lwhere the liquid and gas meet at the lowern'iost part of the froth body 5 the froth body is constantly ,added to below, and the froth is constantly moving up; and is likewise constantlyl being broken up at its upper surface. llfurthermore it will be noted that. because pans cover a substantial proportion of each floor area, and because the spreader cones are spaced between the pans, the tendency of the spreader cones is to throw the liquid horizontally outwardly under the pans. This is clearly indicated by the arrows in li`ig. 5. YConsequently the liquid that picked up and moved upwardly by the upwardly flowing gas cannot, even if moved upwardly in fairly large bodies of liquid rather than as froth tilius, iiinnediately reach a position where it could llow over the edge of a pan. lt must, as indicated by the dottedline arrows in Fig. 5, follow a more or less tortuous upward path to reach the liquid surface surrouinlingthe pans; and in following such tortuous path it is, of course, at all times coming into contact with gas that is moving up thrinigh or with the body of froth. lThe gas that coines up under the paus must also' follow a long tortuous path to reach the froth surface, thus increasing its Contact with the liquid. find the spreading of the gas under the .spreader cones has also the same effect.

'l`he suiii-tiiital result of these arrangements is that aji'ery high eliifciency of action is obtained in inv l aber, that action being due to the ure i 'mate contact between the gas and l d also due in some measure y i reii` the liquid flows from one u ti it iiecef-Ifsarily freed of gas. le lower ends of the ioweriuost tubes 3l t iieefesaiy to employ spreader cones7 psll are there used inere- L passing upwardly gil find it; may

'iltlll be noted in this connection that cones 33, which are made of hollow sheet metal, as is indicated in Fig. 5, protect the lower ends of tubes 3l and prevent. gas from flowing directly upwardly from the perforated floor o through the tubes. The gas that flows through the floor perforations directly below a cone 33 cannot flow directly up through the tubes, but is turned horizontally under the cone, flowing out under' its lower edge, and this outward radial liow of gas under and aroundeach cone ,helps inffiowing'the Clear liquid radially outwardly over the floor around each cone, this aiding in aV widespread of the liquid flow, thus decreasing S0 the thickness ofliquid tilin and increasing the intimacy of contact between the upwardly flowing gas and the liquid. This outward radial flow of gas increases the length of its path to reach the froth surface; causes meeting and turbulence between the adial gas and liquid flows from adjacentleones; and increases both the time period and the intiniacyof contact between gas and liquid.

In a process of treating gases or vapors by Contact with liquid, continuously forming and maintaining homogeneous body of froth in which the liquid is substantially wholly in the foi-in of film surrounding bubbles of gas or vapor, the froth being continuously foruied by introduction of both liquid and gas or vapor in intimate contact at the lower part of the froth body thus building up the froth body froiniits lower part, and 10o continuously breaking up the froth and liberating the gas or vapor at the upper surface of the froth body at the same rate at which the froth is for ied.

In witness that l elaiin the foregoing I l les have' hereunto subscribed my name this 9th day of April, 192i.`

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