US1857816A - Distillation apparatus and the like - Google Patents

Description

Patented May 10,',1932

UNITED .sTATE-s "IMT,F-Nli *OFFICE Faenza. LICHTENTHAELEB, or NEWTON HIGHLANDS, MASSACHUSETTS i DIsrILLATroN v,Ar'iuinai'us' am; THE LIKE? `Application led September 21,1927. :Serial No.` 221,062.

Y The prese-nt invention-relates to improvements in apparatus for distillation, or 'the like, by which I mean to include absorbing,

' condensing, dissolving or chemically combin" ing vapor bearing air or other gas, on the one hand, and a liquid Von the other hand.

'The eciency-of distillation columns demixture in successive stages of the opposingstreams of' vapor and liquid than has been heretofore possible. In operating contact towers af system of decks and seals has been employed to retard the flow of liquid in order t'o bring-in the time elementmost favorable for an interchange equilibrium. In this manner progressive stages of interchange are accomplished and the vtimeof contact is made controllable by trapping the requisite amount ofliquid at the respective ile'cks. The liquid flows from deck tizio 'deck'throu 'hhsealed 'conductorsor o'etrow` pi es'an t e vapor or gas is cause o bubbleiro of 'vaporseals known as bubble caps. By thus 'trapping the liquid the disparity of the liquid 85 volume'as compared to vapor or gas volume is overcome. The. requisite contact for .favors able interchange is thus made possible no mat- ,ter how small the liquid volume. -h h ,The passage of vapor orj gas throu entrapped liquid on horizontal dec s by means of perforations or' passages in the decks offers the advantage of mosteconomical use l'of tower cros's" sections. However, the desired minimum depth of liquid on the decks has not heretofore been a practical operatin condition especially in the case of towersy o large diameter.` The, level of the respective decks cannot be accurately' established and the greater the diameter of the tower the greater the inaccuracy ofthe deck level so lb `the use of which the advantages herein- YThis has been selected forpurposes ,of ill that a.' considerable depth of liquid must be maintained on perforated decks to insure a suicient liquid seal at `all points. For example, the limitations of tower construction are such that it hasv not been possible to maintain as little depth as onehalf inch` over decks ofdiameters now commonly employed. A' liquid depth of approximately four inches is commonly required and this creates a back pressure often unfavorable and in the case 60- of vacuum distillation destructive to the object sought. In fact the size of towers now being designed is unfavorably restricted by the mechanical diiculties 'of leveling the decks.- t 05 My invention is based on the observed fact that in distillation columns ofstandard construction the efficiency of interchange de-v creases per deck as the diameter of the column increases, whereas in single cap columns l of small diameter full lefficiency is' maintained. This may be due to the fact that multiple cap columns handle the vapor in parallel streams `while the liquid in a single .stream contacts with the vapor stream in seu ries fashion. At any given deck the rising vapor is of uniform composition but theliquid changes in its composition as it flows across. the deck and consequently it may reach a condition of equilibrium of exchange before 8 all th a s are -su 1 d, ugh-the @trapped liquid by means e c p pp le In one of its aspects, therefore, my inven-l tion consists in securing high eiciency in dis- .tillation columns or the like by dividing the descending liquid into separate parallel streams and subjectingeach stream to the interaction of the ascending counter-flowin vapor. In this way .thedescending liqui streams arecaused to parallel the ascending vapor streams. One manner of reaching this 9 result is by supplying a liquid conductor or overflow pipe for each cap. y A

These and other features of the invention, including a novel and efiicient form of cap o5 a ove set forth'may be secured, will be best understood and a preciated from the follow- 'ing description o a distillation column fitted with -a preferred embodiment of the cap. no

' the construction of the contact deck of the cap and Figs. 3 and 4 are fragmentary views illustlraing alternative constructions of the cap The body of the column 10 is made of sheet steel and is provided with a series of horizontal sheet steel decks 12 riveted in place. Each cap comprises a complete, unitary, liquid sealed overliow and contact device and each Vertical pair of caps cooperate in such manner as to furnish four liquid sealed contact areas or cap decks. The caps are herein shown as circular in cross section but they may be hexagonal or any other appropriate shape, so long astheir general construction '4 is such that they may be assembled in a compact arrangement in the decks ofthe column.

Each cap comprises an upright dam 14 having 'a serrated upper edge which by its height above the deck determines the depth of the liquid seal. Concentrically disposed with respect to the dam 14 and secured in place by bolts 26 is an inverted cap member 16 having a shallow dam 18 and a slotted contact area 20. A liquid conductor orover-- liow pipe 24 drains the contact area 20 being provided with a circular dam 22 at its upper end to form a seal. The dam 22.is slotted to weaken the surface lilm and better distribute the flowIv of liquid from the contact area under the small head. It will be understood that the liquid upon the contact deck or area 2O is kept in a conti-nualturmoil by the ascending vapor. Onthis account and on account of the vapor pressure in the slots, the liquid remains upon the deck. The 'inward ilow of the liquid toward the dam 22 is interrupted by the vapor passing through it and it has been found in practice that a perforated dam is all that is required to maintain the small head of liquid desire over fthe contact area. LConcentrically arranged. within the cap members is a vapor riser 28 secured in place by legs 30 attached to the contact surface of the contact area 20 and having a flaring apron 32 which deects liquid Howing over the sealing dam 14 outwardly behind the angeLor dam 18 of the cap member 16. The vapor riser extends upwardly through the dam 14 and in near proximity to the curved baleplate-48 by which vapor wardly. v v

Each device comprises also a cap member 40 having an exterior contact area 44 vand being secured in place by legs 42 withits lower edge disposed below'the plane'of the dam 14 thus completing a. liqu`id seal-for through the riser is deflected out-- the deck about each dam. The contact area. 44 has a peripheral dam 45 and is slotted radially as shown more clearly in Fig. 2. It is provided centrall with a 'sealing chamber 46 of which the baille plate 48 constitutes the bottom. The liquid conductor or overflow pipe 24 of the'cap in the next higher deck extends into the sealing chamber 46 to a point below its serrated annular wall.

The lower surface o f the baffle plate 48 is given the compound curvature best suited to baiie and interruptfentraiined liquid in the vapor stream. It acts to collect the drops of liquid impinging upon its surfaceand discharge the liquid in appreciable volume from its convex center.

Fig. '3 illustrates an alternative form of contact area'l 54 in which perforations 56- are provided within` the marginal {iange 55.

Fig. 4 illustrates still another modification of the contact area in which-divergent surfaces 64 are provided for conducting the liquid to the slots within the marginal flange 65 of the deck. Other shapes and arrangements of slots and perforations could obviously be used within the scope of ,my invention.`

- In operating a tower such as that above described the liquid from each deck overfiows at the serrated edge of the dam 14 and then iows over the dam 18 upon the interior contact area 2O on its way to the liquid con-A ductor or overflow pipe 24. Vapor meanwhile bubbles yup through the slots or perforations in the contact area 20, the depth of the liquid through which the vapor must be made to bubble being determined in part bythe height of the flange or dam 22. The

liquid passing down the conductpr 24 is' trapped by the wall, r46 ofthe liquid seal chamber and ows out over the serrated edge of the wallV upon the exterior contact area 44. The ascending stream of vapor is direct- I ed to the deck 44 by the vapor riserY 28 and is dispersed whenreaching it by the bale plate 48 as already explained". The height o f the dam 45 determines the depth of the liquid through which the vapor must bubble at this deck. Some liquid may.' leak through the contact area 44 of the cap but th1s 1s prevented from-entering the vapor riser by the` baie plate 48 andfalls either outside of the sealing flange 14 or inside the seallng flange l14 where it will be deected by the apron 32 into the collecting basin formed in the lower cap element by the dam 18. Anyexcess 'of vapor or gas may pass out under the edge of the cap member 40 without causlng undue b ack pressure, and .the space' outslde the vapor riser 28 affords also possible relief 1n this respect. v

From 'theforegoing description it will be noted that interchange is veected eiiciently on account f of the separate and individual liquid supply to each cap, which comprises i an aliquot part of the total liquidstream, the

caps for liquid flow. The caps can therefore be placed close together as is mechanically convenient allowing only for down flow of the liquid, thus still further economizing sectional area of the column.

, It will also be observed that in using the novel caps of my;invention twice as many areas ofcontact deck are secured as there are complete column decks 12; in other words, for each associated pair of caps carried by two adjacent column decks, four areas of cap 'contact deck are provided. From this it will be apparent that the number of column decks may be reduced and appreciable savings made in the cost of column construction.

The deck level -error is minimized by substituting a number of small cap decks 'independently sealed inplace of a single liquid pool sealing all thecaps as in present commercial construction. The .shallow seals made possible insure low operating pressure and minimum back pressure. This is extremely favorable for employment in vacuum distillation and for absorbing or scrubbing operations limited in respect 4to allowable back pressure. The shallow seals moreover present the additional advantages in that the amount of `liquid in process is smaller than that heretofore required' in tower operations. This means less weight to support, lower investment ch'arge on material in process and quicker response to changes in adjustment.

Further a feature of safety is introduced in that excessive pressures such as might be caused in high temperature ,operations as in petroleum distillations, by the accidental introduction of water, are quicklyand freely released and dissipated without danger of bursting the tower.

Having thus described'my invention, I j' I I vapor passages and being disposed between claim 1. In a/distillation column, or the like,a

deck having a plurality of openings, a decksealing dam about each opening, a vapor riser concentric with and spaced from each sealing dam, andan overow pipe suspendedbeneath the vapor riser, and means for liquid sealing the end ofthe overflow pipe.

2. In a distillation column,.or-the like, a .deck-"havingwJ plurality of dams, members cooperating with said dams `to form deck seals, 'a vapor riser concentric with each'dam, a cap havi an interior'surface constituting a contact area-below the vapor riser and an overflow 'pipe carried by the cap.`

3. ,In a distillation column, or the like, a deck-having a plurality of' dams, a vapor riser concentric'with each dam, a cap having an interior surface constitutingl a contact area below the vapor-riser, an overflow pipe carriedk by the cap, and means`I forhquid sealing the overiow pipe'.

4. In a distillationacolumn, or the like, decks each having projecting above its surface a dam anda concentric vapor riser, and below its surface a concentric contact'area and overflow pipe.

5. In a distillation column, or the like, ad-

4 jacent decks with overflow openings, a perforated plate providinga contact area and a connected down-pipe carried by one deck co-operating with a second perforated plate providing a contact areaand liquid seal carried by the other deck.y

6. A bubble cap for distillation column, or the like, comprising a liquid down-pipe,

a concentric vapor riser of larger diameter than the down-pipe, and a concentric cap member of greater diameter than the vapor riser carrying a liquid-sealing chamber and having an outer contact deck.

7. In a column for distillation purposes, or the like, a bubble cap havingtwo perforated contact decks spaced one above the other, and a vapor riser so located as to receive vapor from the lower deck and direct it to the upper deck. p 7

8. In a column for distillation purposes, or the like, a bubble cap having two spaced perforated contact decks, means for causing liquid to flow outwardly and escape from the periphery of one deck, and means for causingliquid to flow inwardly and escape from the center of the other deck. L

9. In a distillation column, or the like, a series of decks with overiow openings, a vapor riser and plates providing two independent perforated'contact areas associated with each deck o l ning. l

10. In a disti ation column or the like a plurality of spaced decks, adjacent decks havingliquidesealed openings therein and a liquid-sealed down pipe, Aand a plate associated therewith providing a liquid-covered deck. area having a surface provided with the decks.'

11. In mgglistillation column or the like, a deckliaving a plurality of openings, a dam at each opening, a member cooperating with the dam to' fform a deck seal, an overflow pipe located beneath each opening and being 'liquid-sealed independently of the deck seal, and

respectively, and a capf'element' associated column, or the like,

with .a va or o enin andfforming both a"` liquid sealpfor ghe oerlow from anupper i deck and a baffle for the vapor o ening, anda Contact deck associated with sai cap element. 13. In a distillation column, or the like, an overflow pipe, a cap element providing a liquid seal therefor, a perforated plate providing a contact area surrounding said seal, and means for causing vapor to pass through the liquid on the Contact area.y l

Intestimony whereof I havey affixed my signature. f

FRANK E.V LICHTENTHAELER.;

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