US1886957A - Method and apparatus for dephlegmation - Google Patents

Description

.NOV. 8, 1932. I 1 C, HUFF 1,886,957-

METHOD AND APPARATUS FOR DEPHLEGMATION Filed March 10, 1926 2 SheetSr-Sheet l Nov. 8, 1932.

L. c. HUEF METHOD AND APPARATUS FOR DEPHLEGMATION 2 Sheets-Sheet 2 Filed March lO, 1926 jing/22j@ VSti Patented Nov. 8, 1932 y Y UNIT" rf LYll/[AN C. HUFF, O1? CHCAGO, ILLINOS, ASSIGNOR TQ UNIVERSAL OIL PRODUCTS COMPANY, OFUCHICAC-IO, ILLINOS, A CORPORATION OF .SOUTH DAKOTA METHOD Ann nrrnaarus ron DnrirLneMn'rIoN i' Application :'led March 10, v192.6. Serial ANo. 93,557.

rlhis invention relates to improvements in method of and apparatus for dephlegmation, and refers more particularlyto that type of dephlegmation in which the vapors in their upward passage through the tower are Acaused to sweep over a descending. iilmor str-sam of cooling liquid, thereby securing a thorough intermingling between the vapors and the liquid cooling medium.

The specific embodiment of the present inv-ention comprises a tower in which lthere are located a number of spaced decks. Each of the decks is provided with a number of vertical conduits extending therethrough, 1I functioning as passages for the upward ascending vapors and for the downwardly descending-liquid cooling means. The upper end of each conduit is located above the surface of vthe declr in order that there will be a pool of liquid maintainedon each deck, the arrangement being such that the liquid from eachldeck overflows through the vertical con duits, the lower end of each conduit preferably terminating below the liquid levelof the pool maintained onV the deck immediately -below. This prevents the falling liquid from disturbingor agitating the liquid on the decks, and also creates circulation of the lower strata-ofliquid on each` tray. y v v One of the Vprincipal advantages ofthe present :invention resides in the fact that it is possible to have a high pressure diiferential between' the ,bottom of the tower and the top thereof without in 'any way disturbing the liquid on the trays, thus preventing siphoning of the liquid due to sudden pressure differential.

' The present Vinvention also permits ofav high vapor velocity over the liquid surfaces asjwe'll as aA uniform distribution of liquid over all parts of the tower.

Many other advantages will be hereinafter brought out.

In thedrawings, Fig. 1 is a vertical sec# tional view of the tower embodying the' presentinvention.. V

^ F ig. 2 is an enlarged vertical sectional View showing two spaced decls with connecting .50 conduits therebetween.

Fig. 3 is an enlarged cross sectional View taken on line 3-3 of Fig. 2;

' Fig. 4 is an enlargedY cross sectional view taken on line 4 4 of Fig. 2.v I 1 Fig. 5 is a view similar to Fig. 2 showing a slightly modified formof construction.

Fig. 6 is a cross ysectional view taken on line 6 6 of Fig. 5.

Fig. 7 is an enlarged cross sectional view` similar to Fig. 5 illustrating another form of construction.

Referring more particularly to the draw-'i ings, 1 designates a vertical shell or tower which may have the removable bottom 2 and removable top 3. The tower may be provided with the liquid drawoff 4 controlled by the valve 5, vapor inlet 6 controlled by valve 7, vapor outlet 8 controlled by the valve 9, cooling liquid inlet 10 controlled by the valve 11. The lower interior space of the dephlegmator may be provided with baffles illustrated diagrammatically at Y 12.` `The auxiliary liquid inlet pipe 13 controlled by valve 14 may also be provided. The above described'parts constitute part of a standard form of dephlegmator, and I do not claim any novelty in their use in the present invention, except in combination. i Y i A,

Referring now more particularlyfto some of the novel features of the present invention,

in the upper parti-of the tower 1 may be mounted a number of vertically spaced circular plates 15, which plates havethe same diameter as the internal diameter of the tower. The plates are solid, except for the apertures 16 which apertures are adapted to receive theupper end of the vertical conduits 17. The plates 15 function as decks vor trays. Each-conduit 17 may comprise an upper section 18 and a lower section 19. The upper lip of the uppersection may be liared outwardly as shown at 2O to facilitate the overflow of liquid `over its edge. J ust below the point of connection with each plate 15, the conduit 17 maybe provided with the annular shoulder 21 and also with the inlet pipes 22 intermediate its length. As shown, more clearly in Fig. 3, the inlet pipes 22 are slightly rounded or curved in shape so that the vapors entering have imparted thereto a whirling movement in the space 23'as indicated by the arrows. This whirling motion transmitted to the vapors entering the inlets 22, serves to whirl said vapors over the descending film of liquid overflowing the lips 2O of each conduit and flowing down over the interior walls of the conduits 17 resulting in a more uniform mixing of the vapors in t ieirupward passage. 'Ihelower end of the lower portion 19 of each conduit may be provided with the spaced studs or supports 24 adapted to be supported on the surface of the deck or tray immediately below. The arrangement is such that the liquid overflowing thel outwardly flaring lips 2O and flowing down the inner walls of the tubes 17 will be discharged in the kspaces between the supports 24C into the body of liquid 25 maintained on each deck. The purpose of discharging the downwardly descending' stream of liquid into the lower strata of each pool of liquid 25 is t prevent agitation or disturbance vof-such liquid in the pool in order to get a uniform overflow of liquid into the down pipes 17.

The height-of theupper portion 18 of each conduit is predetermined to regulate the height of the pool of liquid carried on each deck.

In operation the vaporswill be introduced through the vapor inlet 6, valve 7 being opened, and will pass upward past the baffles 12into the first inlet pipes 22 in the conduit 17. Cooling liquid may be introduced either into the lines or 13, or both, by obvious manipulation of the valves. `Assuming that cooling liquid is Vintroduced through the line 10, this liquidwill form a pool on the upper deck 15, the height being regulated by the height of the portion 18 of the conduit. When the height of the pool is above the overflow 20, said liquid will iiow downwardly along the walls of each of the conduits overflowing near the bot-tom in the lower strata of the pools of liquidmaintained on the decks below.- The vapors on entering the inlets 22 will have imparted thereto a whirling motion which will cause said vapors to sweep over the film of downwardly descending liquid resulting in a very complete intermingling of vapors and liquid and efficient dephlegmation. The vapors will be maintained in the tower for a maximum length of time, those remaining uncondensed after` passage through the entire dephlegmator, being withdrawn through the vapor outlet line 8 the valve 9 being open. Liquid collecting in the bottom of the tower may be withdrawn through line 4rby opening valve 5.

By proper regulation of the temperatures and amount of cooling liquid introduced, it is possible to accurately control the end point of the vapors being discharged through the pipe 8.

Referring to the modified forms of construction shown in Figs. 5, 6 and 7, in Figs.

height on the decks by means of the y annular supporting lug 24. The base or lower endo-f each conduit 17 terminates in the' liquid body 25 of the deck below but'at a short distance above the surface of each deck 15 having no supports similar to 24 (Fig. 4:) This dees not interfere in any way with the operation.

In the modification shown in Fig. 7, each conduit 17 may be provided with annular lugs 24 intermediate their height, said lugs resting on and being supported by the decks 15". Instead of being provided with vapor inlets intermediate their length, vapors are caused to pass around the lower end past the deflectors 26- which impart a whirling swirlingmotion to the rising vapors. The upper lip of each conduit 17 is outwardlyfflared as shown at for the-.purpose of facilitating an even and uniform flow of downwardly descending liquid over the interior Wall'of the conduit.

vThe lower end of each vertical conduit 17 terminates above the surface of the pool of liquid the downwardly descending liquid dropping into the liquid retainer '27 which may have screw threaded connection with the lugs 28 fastened on each tray 15. The arrangement is such thatthe lower end of each of the retaining elements 27 terminates above the surface of the tray 15 thus allowing the liquid to How out into the lower strata of liquid forming pool-25". The lugs 28 of which there` may be anyl number, are spaced from each other so as not to interfere with this i'iow of liquid. The upper end of each retainer element 27 is preferably above the plane of the upper lip 20 of each conduit 17".

VIn use and operation, the various modifica-` tions shown in the drawings -will function in substantially a similar manner to the tower and interior parts illustrated in Figs. 1 to 4. A further object of placing the top of each retaining element 27 above the liquid level is to reduce splashing and consequent disturbance of the liquid overflowing into the conduits 17". rIhe baffles 12 may be perforated if desired, and it will be apparent from a study of Figs. 5 and 6 that the vapor inlets 22 being placed on a tangent will impart whirling motion tothe vapors. The Vvertical conduits are preferably staggered in alternate pans. The vapors sweep past the downwardly descending nlm of cooling liquid, and do not bubble up through the liquid pools. The vapors are therefore thoroughly agitated as they sweep past the surface of the liquid..V It is proposed that the vapor velocity through the risers shall be suihciently high to create a decided swirling action in the verticall conduits, resulting in an efiicient scrubbing action between the vapors'and the descending film of cooling liquid. One of the main objects ofthe present invention is that-the vapor velocity may be maintained relatively high without holding back the liquid.

Another advantage is that it is impossible for the liquid on the trays to siphon downwardly or back into the still, which is possible in towers equipped with bubble caps andV the like. This siphoning is caused by a sudden generation of pressure in the top of the tower causing the liquid on the trays to siphon downwardly and back into the stills. In the present invention, it is impossible for anyv of the liquid in the trays to flow downwardly, excepting only that portion which is overflowing into the conduits regardless of the dierences in pressure between the top and bottom of the tower. e

The present invention may be installed in connection with a cracking plant operated under superatmospheric pressure, or may be used for fractionating at atmospheric pressures. It is not necessarily limited to hydrocarbons, but may be used in the treatment of alcohol and like liquids.

Another advantage of discharging the downwardly descending liquid from each conduit into the pool below, is that it prevents the accumulation of carbon, silt and the like. By discharging this downwardly descending film of liquid from each conduit into the pool below andv below the liquid level thereof, I thereby form a seal preventing thevapors from entering the riser through the bottom opening.

I do not wishto limit myself in any way to any form of means for imparting a whirlinU swirling motion to the vapors, as this may ta e any form.

I claim as my invention 1. A tower, comprising an elongated shell having spaced horizontally superimposed trays disposed throughout its height, each tray being provided with vertically disposed conduits each having a portion above the tray and a portion below the tray, vapor inlet means communicating with said vertically disposed conduits comprising lateral openings of restricted cross-section for deflecting and imparting a swirling motion to the vapors introduced thereto, and a liquid inlet and a liquid outlet respectively located at the upper and lower portions of said tower.

2. A tower, comprising an elongated shell having spaced horizontally superimposed trays disposed throughout its height, each tray being provided with vertically disposedy conduits, each having a portion above the tray and a portion below the tray, the upper ends of eachconduit being flared outwardly, vapor inlet means communicating with said Vertical- 3. A tower, comprising an elongated shell having f spaced horizontally superimposed trays disposed throughout its height, each tray being provided with vertically disposed conduits each having a portionabove the tray and a, portion below the tray, vapor inlet means communicating with each of said vertically disposed conduits comprising lateral openings of restricted cross-section disposed on said conduits for deiiecting and imparting a swirling motion to the-vapors introduced theretoa liquid inlet and a liquid outlet communicating with said tower .at the respective upper and lower portions thereof, and means for maintaining superatmospherick pressure in said tower. y y

4. A processv for separating lighter from heavier cracked gases andvapors in a mixture of hydrocarbon oil constituents from a cracking still, which consists in introducing the mixture at the lower portion of a tower and causing v'aporsto ascend generally vertically therethrough, causing said ascending vapors to divide into streams each having a restricted cross sectional area, in maintaining the temperature in the upper portion of said tower suiiiciently low to condense some of the heavier cracked constituents,.in causing the condensed `heavier cracked constituents to iiow downwardly in iilmy annular streams surrounding vsaid ascending vapors and in introducing the vapors to said ascending streams in a directiontangential to said annular streams, whereby the ascension of the vapors combined with the tangential introduction give the vapors a helical course contacting with said descending annular stream of condensed heavier cracked constituents.

5. A process of treating the gas and vapor mixture from an oil cracking process, to separate by condensation heavier cracked constituents as reflux condensate and lighter cracked constituents as a mixture of uncondensable gases and constituents amenable to Y refining for use as a motor fuel, which consists in iiowing a cooling liquid containing condensed heavier cracked constituents generally downward and causing vapors to ascend generally upward through a common zone of dephlegmation, dividing the ascending vapors Yinto a plurality i `of restricted streams, dividing the cooling fluid into a plu; rality ofannular film-like streams surrounding said ascending vapor vstreams and descending counter-current thereto, and effecting intimate heat interchange relation he` tween the respective liquid and vapor streams by introducing the vapors to the vapor streams tangential vto said annular liquid streams to give the vapors a helical-course in contact with said annular streams.

6. Apparatus for treating the hydrocarbon gas and vapor mixture 'from an oil cracking process, comprising in combination a shell, means for introducing the said mixture to the lower portion of said shell, means for effecting a descentthrough said shell `of cooling liquid containing condensed heavier cracked constituents, a plurality of unobstructed vertical tubes mounted in said shell in horizontally spaced relation, means for causing the vvapors to divide and pass upwardly throughA said tubes in separate streams, means for causing said cooling Huid to descend in films along the inner surface of said tubes, each of said tubes having its vapor inlet mounted laterally and tangential to the surface thereof, whereby the vapors are caused' to traverse a helical path in contact with said lm in ascending said tube to effect an intimate physical Contact and direct heat interchange relation therewith.

LA method of dephlegmation in an oil cracking process to separate lighter from heavier fractions, comprising introducing hydrocarbon vapors to the lower portion of a dephlegmating zone to pass through a series of spaced compartments provided with vertical conduits of restricted cross sectional area to cause said vapors tocondense while ascending therethrough, introducing a liquid cooling medium to the upper portion of said dephlegmating zone to Contact and commingle with said ascending vapors, and imparting a swirling action to said vapors within said conduits by their introduction thereto from said compartments vthrough lateral openings of restricted cross section disposed thereon.

LYMAN C. HUFF.

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