US2345319A - Heat exchange - Google Patents

Description

March 28, 1944. E, BERTRAM ET AL 2,345,319

HEAT EXCHANGE Filed March 30, 1942 Patented Mar. 28, 1944 'l UNITED STATES PATENT ori-ice name' YA. Be ana pavia Fulton, Flushing, N. Y., assignors to The Lum--A mus Company, New York, N. Y., a. corporation of Delaware application March so, 1942, serial No. 438388 y s claims. (ci. esi-11) This invention relates to a fractionation column, bubble tower, vapor absorption device or-other type of liquid and gas contact apparatus, and more particularly t an apparatus of this general character wherein hot or cold mediums may be introduced at one or more points into the column ioraccurately controlling the temperature therein. I Y

An object of the invention is` toY provide a fractionation column, such as an ammonia-absorponunit with an improved form of heat exchanger for the more accurate temperature control therein.

A further object of the invention is to c'on-A struct a liquid contact column in such a manner that the plurality of heat exchangers'used may be readily inserted into thecolumn or removed therefrom.

A still further object of the invention is to provide an improved form of 4absorber in which each ofthe heat exchange units is provided with a iixed top tray having a plurality of perforations therein'above the tube bundle for the purposeof collecting descending liquids Vand dis,-

,` tributing' them over the .tubes of the bundle in heat exchange relation.

l While theinvention may be used in various types-of fractionation or absorption columns, we-

have shown it in the accompanying drawing as applied to a multiple-deck bubble tower. v

In the drawing:

Fig-1 is a side view of the fractionation tower drawn partly in Gross-section and showing the bubble decks and the V.relation therewith of the heat exchangers. i

gig. 2 is'a vertical 'section through one of the heat exchangers taken on line 2-2 of Fig. 1

looking in the direction of the arrows.

Fig'. 3 is 'a side elevational view of.one of the heat-exchangers with portions thereof broken away to inustrate the tray support.

Fig. 4 Visa top4 plan view of one of the heat fractionation tower Il) of suitable diameter and height is provided with a suitable number of horizontal bubble decks I3. The column is pro- 'vided with the customary inlet and outlet conduits for introducing and discharging vapors and liquids at the top and bottom thereof as willV be hereinafter referred to.

l0 of the tower.

` preferably below each pair-or bubble decks is,

' is a horizontal section l5 for supporting a complete.heat exchange unit I7. YThese sections may be of any suitable construction to rigidly 5 supportthe exchanger units. In the present insaid frames and to be freelysupported by thev other frame as a. bottom guide. The free end has a iioating head cover and'thus Nis free to l5 move with temperature variations.

Referring to Figs. 2, 3 and 4, each heat exchanger unit ll preferably comprises a plurality of horizontal tubes 23 secured to conventional iioating tube sheet v251m the free end, and a` 2() fixed, tube sheet 2l on the other. The iixed tube sheet 2l is provided with a manifold or Ychannel 29 having inlet and outlet feed conduits 3U Y through which hot or cold iiuid is circulated through the tube lbundle and the free end has a channel 25a.

Bailies 2i and .2in extend between the sides of the column and the heat exchanger guide angles 22. As will be seen in Fig. 2, the upper baille 21a tends to prevent passage of vapors through Y 30 the column except through the heat exchange unit, whereas the companion baiiie 2l at the lower part of the heatY exchange unit serves aV complementary purpose. These bames prefer- Y ably have a perforation to make them freedraining. The liquid Awhich accumulates on the respective decks is carried downward through the customary downppes 24 into the'usual liquid' traps 24a so that therecan be no bypassing of the upwardly moving vapors.

Each heat exchange unit is providedV4 va` liquid distributing tray 3l, having .upstanding side walls 33, such tray being secured to the-xed tube sheet 2l and extending across the top of the tubes in slightly spaced relation thereto to a point adjacent the opposite oating tubesheet `25, from which it is supportedby dowels 26.

' The liquid from downpipe 2I,Ywhieh overiiows the trap chamber 24a, and overruns the tray 3l, is thus distributed by the perforations, over- Athe tubes 23.

Each'heat exchange unit is also provided with a liquid collecting tray or plate 35 welded to the fixed tube sheet 21 below theY tube bundle; such tray being imperiorate. This bottom plate 35 Throughout the column and in this instance, has upstanding side walls 3l but is open at the Each heat exchange unit Il is.' arranged to be demountably secured to one of 2 enen adiacentthe noaung tube sheet 2s from' /which it is spaced a sumcient distance to permit 'the'iree passage of downcoming liquid. Vertical straps or braces I9 are secured to the top tray 3i land the lower tray 35 for supporting the4 freejend of the lower tray,

We have found that a column which is provided with one or more of the removable heat exchanger units a's heretofore described, can be yaccurately controlled as to temperature Vby tributes over the tubes of the bundle where it is '2d collected on bottom plate 35 and drips from the open free end 38. The Yliquid flowing from the bottom plate 95 passes" down in a thin film to.

. the bubble deck immediately below the 4particuper pound.

- seriously obstructed.

lar heat exchanger unit.

We have found particular equipment as an ammonia absorber, in which air and ammonia' are introduced at the point l2 and the water is introduced at 44. The air and unsuccess in using this rich aqua is removed at 48. A drain 49 is provided for cleaning out the column from time to.

time. 4 'As is well known, the production of a predetermined concentration of aqua' is ai'unction of the temperature at the absorption stage. Not only is it necessary to have a minimum temperature to avoid boiling oi! the ammonia, but it is necessary to have a somewhat lower temperature in order to assure the absorption with the minimum amount 'of watercirculation. Furthermore, in ammonia' absorption, the averagelatent heat at 90 F., for example, is approximately 488.5 B. t. u.

In accordancl with our invention, we have foundv it possible 'to' circulate cooling. water througheach .of the Vheat exchange units in seriesj beginning with the coldest water at the bottom, and we were able to obtain a high concentration of aqua with the minimum ilow of water without requiring external pumps, heat exchangers, etc. The arrangement for supporting and securing the heat exchange units through the lateral extensions of the tower formed by the frames I9 and f 19a has also proved especially satisfactory on this type of unit for it is only necessary to have a relatively small diameter column and yet the heat removed is/ jso great that comparatively large bundles are requiredwith the usual temperature 1 0i' available coolingwater. Such bundlescan be projected through. the column with portions 'of shown without departing from the invention.

Such modifications are thus consideredwithin the diameter and transversely centered inthe tower to provide a pair of vertical vapor passages at opposite sides of thebundle, a foraminous liquiddistributing tray overlying said tubebundle and arranged to receive downowing liquid and shed a rain of the liquid upon said tubing, a collecting tray underlying the tube bundle to receive said liquid-after it has' passed through the bundle, a baille within the tower` and disposed at approximately: the lower level of the tube bundle and closing' the Alower end 'of one of said passages, and'a baffle within the tower and dis- L posed at approximately the upper-level of the tube bundle and closing the upper end of the other of said vapor passages, said trays and baiiles being constructed and :arranged to cause vapor ascending within the' towerfrom beneath the tube bundle to flow through theiatter crosswise of said 'I rain of liquid. r

2. In a tower for the countercurrent contact of a downilowing liquid and a rising vapor-f said tower having. diametricaliy located lateralV extensions, one of said extensions being closed at its outer end, a removable heat exchanger unit comprising a bundle of horizontal tubing exposed within the tower, means to circulate temperatureconditioning iiuid through said tubing, said means including a head at one end .of said bundle detachably secured to the other of. said extensions and closing the outer end thereof, the bundle extending across the interior of the tower and into kboth of said extensions for support thereby and beingwof materially less yhorizontal width than the mternalidiameter of the tower to provide a pair of vertical vapor passages at oppositesides of the bundle, a Ioraminous liquid-distributing tray overlying said tubebundle and `arranged to receive downiiowing liquid and shed a rain 'of the level of the tubebundle and closing the lower end of one of said passages; and a'baiiie iixed within the tower at approximately the upper level of the 'tube bundle and` closing the upper end of the other of said passages, said trays and baiiles being constructed and arranged to cause vapor ascendingfwithin the tower from beneath the tube bundle fthe tube bundles extending beyond the actualdiameter ofthe column due to the large spaces'provided by the nozzles. The dotted line I0 in Fig. 4

forexample, indicates the extent of the column 'although" the effective cross section in the vicinity construction there is no objectionable restriction in the vapor space so that .the vapor path is not It will be apparent that our invention is ,applicable to different forms of fractionation or to ilow .throughthe latter crosswise of said rain of liquid, said unit including the tube bundle and a downfiowing liquid and arising vap'or, said tower having` diametrically' located apertures, frames extending around said'apertures and said extensions being closed at its outer end, a removable heat exchanger unit comprising a bun'dleofhprizontal tubing exposed within the tower, means to circulate temperature-conditioning uid through said tubing, said means including a head at one end of said bundle detachably asiasie secured to the other of said extensions and closing the outer end thereof. the bundle extending across the interior of the tower and into-both of said extensions for support thereby and being of' a materially less horizontal width than the internal diameter of the tower to provide a pair oi' vertical vapor passages at oppositesides of the bundle, a .foraminous liquid-distributing tray overlying said tube bundle and arranged to receive downowing liquid and shed a rain of the otherfof said passages, said trays vand baiiles being constructed and arranged to cause vapor ascending within the tower `from beneath the tube bundle to flow through the latter crosswise.

of said rain of liquid; and` track means xed within the tower and extending between said extensions, said unit including the tube bundle and trays being removable endwise from the tower along said track means after release oi said bundle Ahead from the respective tower extension.

4. In a tower for contact of a downowing liquid and a vapor, a bundle of heat exchanger `tubing exposed within the,tower and disposed horizontally therein, means to circulate temperature-conditioning fluid through said tubing, a

through the bundle, said bundle being of mate-- rially less width than the internal diameter of the tower and being transversely centered within thetower to afford spaces at opposite sides of the bundle, and vapor-directing means associated with said opposite'sides of the tube bundle, the said trays and the said vapor-directing means 'being constructed and arranged `'to constrain the vapor within the tower to iiow through the tube bundle crosswise oi' said rain of liquid.

5. In a tower for contact of a downilo'wing liquid and a vapor. a heat exchanger unit comprising a bundle of heat exchanger tubing exposed within the tower and` disposed horizontally therein, means to circulate temperature-conditioning uid through said tubing, a foraminous liquid-distributing tray overlying said tube bundle and arranged to receive downfiowing liquid and shed a rain of the liquid upon said tubing, and a collecting tray underlying the tube bundle to receive said liquid after it has passed through the bundle, said bundle being of materially less width than the internal diameter of the tower and being transversely centered within the tower to afford spaces at opposite lsides of the bundle; means supporting said'unit within the tower for horizontal endwise removal therefrom; and

vapor-directing means associated with said opposite sides of the tube bundle, the said traysand the said vapor-directing means being constructed and arranged to constrainl the vapor within` the tower to iiow through the tube bundle crosswise of said rain of liquid.

6. A heat exchanger unit for installation in a vapor-liquid contact tower crosswise of the latter and for removal transversely of the tower, comf prising a bundle of 'parallel horizontal tubes, a iixed tube sheet secured to one end of/'said tubes; aiioating tube sheet -secured to the opposite end of said tubes, means for circulating a heat exchange medium through the tubes, a foraminous liquid-distributing tray overlying the tube bundle to shed a rain of liquid upon the tubes, an imperforate liquid-collecting tray underlying the tube bundle, both of said trays being secured at one end thereof to one of the tube sheets, a

slidable supporting connection between the other tube sheet and the opposite end portion of said foraminous tray to support the latter and permit movement of the floating tube sheet under expansion and contraction of the tubes, and a` suspen-

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