US2361021A

US2361021A - Bubble cap and down-pipe unit

Info

Publication number: US2361021A
Application number: US456738A
Authority: US
Inventors: John A Gibb; James F Thornton
Original assignee: Lummus Co
Current assignee: CB&I Technology Inc
Priority date: 1942-08-31
Filing date: 1942-08-31
Publication date: 1944-10-24
Anticipated expiration: 1961-10-24

Description

reason, the upper edge oi ange `it is desirably not serrated.l These supporting members may be made integrally with plate and flange 26 if desired. Flange 2S is also provided with a plurality of lugs 32, whereby plate 25 is securely fastened to plate it as by means of the studv bolts 33 and the nuts 3d.

Downpipe ill is provided at its lower end with a tray 35 for the collection of the liquid ilowing downwardly therethrough. This tray constitutes` the downpipe seal pan of our combined unit. For the proper distribution of the downowing liquid onto the next lower bubble cap and downpipe unit, tray 35 is provided at its outer periphery.

with an upwardly extending ilange 35, which is desirably serrated as at 3'? so that the liquid can he more evenly distributed in a plurality of smell streams, This tray may be attached to the lower edge'of downpipe irl in any suitable manner as by welding, for example. Accordingly, downpipe it is provided with a plurality of openings 38 in. the lower portion thereof for the passage of thev downiiowing liquid onto tray 85. The upper edge of iienge 38 desirably extends above these several openings to provide the necessary vapor seal. In the preferred form of embodiment of our invention, suitable provision is mede so that each bubble cap and downpipe unit rests on and is separctcd by the next lower unit. For this purpose, ilange 3S is desirably provided with a plurality of outwardly extending lugs d, which may be made integral therewith. Each of these lugs is suitably slotted as at li for the insertion of a A ring-supporting member 42 which is suitably comprise a suitable gasket material provided with a flexible metallic cover, When the several bubble cap and downplpe units are inserted in column i6 one above the other, the eilect of the weight of such yunits is to compress the gasket It downwardly against flange 25 and outwardly against the wall of column -Il. In this way, a substantially tight seal is madel with the column wall, and vapor leakage around each 'unit is substantially prevented.

Our improved bubble cap and downpipe oonsquare inches (cross-sectional crea ci' column (452 square inchesi less aree ci' plate it' and downpipe l (314 sousre inchesl). Since the superficiel aree. of the column (total cross-sectional area of the column (452 square inches) less the cross-sectional area of the downpipe (78.5 square inchesl) is approximately 373.5 square inches, the riser area is about 30.5% of the supericial area of the column. This percentage compares favorably with the customary 15% or less.

Furthermore, this improved construction provides a relatively large slot area for the contact of the rising'vapors with the liquid maintained on trough (E. In the above exemple, the slotted circumference of the vbubble cap portion is approximately i'Li inches, and a very eective turbulence around the slots on this cap portion is provided. In addition, a prolonged contact of the vapors with the liquid is provided by the pss sage of the rising vapors through the liquid spray which is caused by the overiiow of liquid from tray 35. The diameter of this tray t5 is desirebly substantially tiresome es the inner diameter of plate t5 but may also be somewhat greater where such construction improves the vaporliqud contact. Preferably, the respective annular areas 28, 2o, and tu are made as nearly equal as possible so as to reduce the pressure drop therethrough to es low e degree as possible although annular area du may be somewhat less than either of the other two. In the above example, the annular area ES is 138 square inches as already noted; the annular area 28 is 137.5

square inches (crosssectional area of plate i8I '(35.4 square inches) less cross-sectional area of Aplante i5 (176.5 square inches)); and the annuilar area.` t0 is 98 square inches (crosssectional area ofy plate 25 (176.5 square inches) less crosssectional area of downplpe inches) Y AThe spacing between respectivo mits in a colill (78.5 square umn may be any distance that is found desirable structionv has several features which particularly characterize it. The primary features are the provision of an exceptionally large downpipe Il or clownilowV area in the center of the column and the provision at .the same timcof an exceptionally'la'rgev vapor riser aree 2l around the downpipe. This riser aree'` may be as much as 30% or more of the superncial tower area instead of the customary 15% or less. It will thus bessen that a column provided with our improved units has e. very much-greater vapor-handling capacity than the ordinary bubble deckvcolumn. For example, in 9. column having o. diameter of 24 inches, the following dimensions are suitable. The dlameter'of downpipe 14 is 10 inches; the outer diameter of annular plate iB is 20 inches:

or necessary. In addition, provision (not shown) may be made for separating entrained liquid between each pair of units.

Our improved bubble cap and downplpe oonstruction is particularly applicable for use in small diameter columns ranging from 6 to 24 inches in diameter. In such case, each column is desirably provided with e plurality of such units superimposed one upon the other. Qur invention is also applicable, however, for use in columns of larger diameter. In such case, multiple superimposed bubble cap andv downpipe unitn are used in any mutable fashion. Altlmush we have described our invention ln connection with a circular column, it is equally applicable to a column 4 having any other type of cross-sectional area. In

all cases, however, downpipe i4 is preferably positioned substantially centrally within the cul-l umn. L 4

Furthermore, our improved device Ais useful in the deseration of water auch as boiler feed water.

In-such ycese the water throush the col-` y umn in countercurrent contact with steam.' BeA cause of the large contact area between the down andthe inner diameter of annular plate 2B is 15 inches.v` -In this case, 'the downpipe ar'ea is aD- proximately 78.5 square inches, and 'theiriser creo.` (annular space Il) is approximately .138

flowingv liquid and the rising vaporswhich our construction provides, Generation of thev water is readily accomplished without any appreciable loss.'

Although we havedescribed ,a vpreferred form of embodiment of our invention; we are aware that modincationsm'oy be made; therefore. onlyV 2,861,0al. such limitationsas appear in the claims append` ed hereinafter should be applied.

We claim:

1. A plurality of combined bubble cap and downpipe units for a-\'fractionating column, said units being in superimposed relation and each unit comprising a downpipe for liquid, a liquidcollecting trough attached to said downpipe near the upper end thereof, said trough having at its outer periphery a flange, the upper edge of which extends above the upper edge of the downpipe, a bubble cap comprising an annular baille provided at its inner periphery with a downwardly extending flange, the lower edge of which extends below the upper edges ofthe downpipe and the rst flange, said annular baille being adapted to i-lt the wall of the column and being positioned above the -downpipeL a plurality of spaced supporting members attached to the under and outer' sides of the bubble cap forming baille and iiange, said supporting members resting on the upper edge of the trough iiange, means to fasten the bubble cap to the trough, a tray attached to the lower end of the downpipe to collect the liquid' flowing downwardly therethrough and to dis;

tribute such liquid onto the next lower unit, a

` plurality oi. spaced outwardly extendingl lugs attached to said tray, a ringsupporting member' carried by each lug, and a ring supported by and attached to said latter members, said ring resting on the bubble cap of the next lower unit.

2. A combined bubble cap and downpipe unit for a fractionating column formed independently of said column and comprising a relatively large diameter vertical downpipe centrally located within the cross section oi the column and free from internal obstruction throughout its length, means borne by said downpipe in a xed relation thereto forming an annular liquid-accumulating trough surrounding the upper end portion of said downpipe and with its outer side spaced materially inward from the inner wall of the column to define therebetween an annular vapor iiow space, the outer side of said trough extending above the level of the upper endpof the downedge oi the outer side o1', the trough and including at its inner periphery an annular flange depending into thetrough to a level below that of the upper edge of the downpipe, said liange being located intermediate the opposite side walls of the trough and the baille with its flange forming, in eiiect, a bubble cap, and the trough, the bade and the column together defining a single annular vapor upiiow passage to constrain. all the vapor ascending within the column around the exterior of the downpipe to pass through liquid accumulated in the trough, and liquid collecting and distributing means attached to the lower end of the downpipe to collect the liquid owing downwardly therethrough, form of the collected liquid a seal to close the lower end of the downpipe and also cause a distributed overflow of the liquid downward from the unit.

4. A plurality of superimposed bubble cap and downpi units for a fractionation column and including an upper unit and a. lower unit each according to claim 2, and wherein the upper unit includes liquid collecting and distributing means to collect the liquid delivered by its downpipe, .form or the collected liquid a'seal to close the lower end of the downpipe and also distribute the overflow of said liquid into the trough of the lower unit, said liquid collecting and distributing means being supported in the upper unit in a i'lxed relation to the lower end of the downpipe.

5. A plurality of superimposed bubble cap and downnip'e units for a fractionation column and including an upper unit and a lower unit, each ci said units comprising a vertical downpipe of relatively large diameter centrally located within the cross-section of the column and free from inter--v nal obstruction throughout its length, means forming an annular liquid-accumulating trough surrounding the upper'end portion of the down pipe and with its outer side spaced materially inward from the inner wall of the col to denne therebetween an annular vapor dow space,

. the outer sidecf the trough extending above the pipe, and an annular baille supported in the unit in a fixed position spaced above the upper edge of the outer side of the trough and including at its inner periphery'an annular flange depending into the trough to alevel below that of the upper edge ofY the downpipe, said flange being located intermediate theopposite side Walls of the trough and the baa with its flange forming. in eect, a bubble cap. and the trough, the baffle and the column together defining a single annular vapor upflow passage to constrain all the vapor ascending within the column around the exterior of the downpipe to pass through liquid .accumulated in the trough.

3. A combined bubble cap and downpipe unit for a `iractionating column formed independent. ly of said column and comprising a relatively large diameter vertical downplpe centrally located within the cross section'of the column and free frominternal obstruction throughout its length,

means borne by said downpipe in a iixed relation thereto and forming an annular liquidaccumulating trough surrounding the upper end portion of said downpipe and with its outer side spaced materially inward from the innefwall of the column to dene therebetween an annular vapor iow space, the outer side of said trough extending /above the level of the upper end'oi? the. downpipe, an annular bane supported in the unit in 'a Afixed position spaced above the upper level of the upper end of the downpipe, and an annular bale spaced above the upper edge of the outer side of the trough and including vat its inner periphery an annular flange depending into the y trough to a level below Vthat of the upper edge oi the downpipe, said ange being located intermediate the opposite side walls of the trough, said baie with its ange forming in eiect a bubble can-and the trough, the bams and the column together dening a single annular vapor upilow passage to constrain all the vapor ascend` ing within the column aroundV the exterior of the downpipe topass through liquid accumulated within the trough, the upper unit including a liquid-collecting and distributing means to collect the liquid delivered by its downpipe, form oi.`

the collected liquid a seal to close the lower end of the downpipe and also distribute the overflow of said liquid into'the trough of the lower unit, and the upper unit also including means to sup port it upon the annular bae of the lower unit, said supporting means .including annular cornpresslble sealing means to form al seal between the outer edge of the baille of the lower unit and tthe inner wall of the column, the upper'unlt being vertically shiftab'le within the column-for /insertion and removal.

s. In combination with the vertical shell c? a l fractionation column, a combined bubble cap and downpipe unit within said shell and formed inde--` pendently thereof and comprising' a vertical downpipeof relativelylarge diameter centrally 4 located within the crees section of seid shell and of relatively large diemetee for large now capeeity, an annuler member home by seid downppe in e fixed relation thereto and forming an annu ler liquid-collecting trough surrounding the upper end portion of the downpi and with its outer side spaeed materially inward from the inner wel! of the shell to dene therebetween en annuler vepor new spaee. the outer side of seid trough extending above the level of the upper.I end of the downplpe. an annular battle supported in the unit in a xedpcslton spaced above the upper edge of the outer side e1' the trough and having et its inner periphery en annular flange depending into the trough to a. level below that of the upper esige of the ownpipe, said enge being loeeted intermediate the eposite 'eide wells exterior of the dowuplpe te 'pass threugh liquid accumulated within the treuen. enel e. liquidcoleetng end dstrbutng pen seeure within the unit and disposed at the lewe: enc?. of the downpipe to collect the liquid eelvered by the letter and form ef the collected Beeld a eeel and ele@ cause a, distributed overew of the liquid, seid- .shell and seid unit being formed te render the unit vertically shtehle bodily within for insertion er remevel.

0E- A. GBE. im F. THGRRTON.

the shell