US2005316A - Apparatus for fractionating hydrocarbon oil vapor - Google Patents

Description

June 18, 1935. F. w. HALL APPARATUS FOR FRACTIONATING HYDROCARBON OIL VAPOR 2 Sheets-Sheet 1 Filed June 15, 1932 INVENTOR BY M5 ATTORNEY F. W. HALL June 18, 1935.

APPARATUS FOR FRAGTIONATING HYDROCARBON OIL VAPOR Filed June 15, 1932 2 Sheets-Sheet 2 ATTORNEY of: Fig. 2

Patented June 18, 1935 PATENT O'FFIQEL' fi APPARATUS FOR FRACTIONATING HYDRO- A CARBON OIL VAPOR 7 Frank W. Hall, PortArthur, Tex assignor to The. Texas Gompany,'New York, N. Y., a corporation of Delaware Application June 15, 1932, Serial No. 61.7;318'

, v y '1 7 Claims. (01.. 196-139) This invention relates to' the fractionation of hydrocarbon oil vapors and particularly to an;

improved apparatus for fractionating developed.

vapors into one or more liquid fractions and a I final vapor fraction. c

The invention contemplatesthe rectification of hydrocarbon oil, cracked or uncracked; under such favorable conditions as to effect the complete separation of desired fractionsi It further contemplates providing an improved type of apparatus peculiarly suited for the efiicient contacting of thevapors undergoing fractionation with refluxingliquid to promote the refluxing of I the heavier constituents of the vapors and the reboiling of the lighter constituents of the refluxing liquidwhile providing adequate length and area of the contact passage for the advancing stream of vapors to obtain sharp fractionation thereof. l

The invention is dephlegmators of'various-types, the apparatus being'of relatively light construction in which the expense of fabrication and handling may be reduced to a minimum. Moreover, the apparatus may be constructed of comparatively expensive corrosion-resistant material and because of the lightness of the structure the total cost should be approximately the same or even less than the cost of present fractionators made of ordinary steel or iron, whereas the life of the apparatus disclosed herein will be greatly increased over that of the usual equipment in similar service.

The invention will be readily understood from a consideration of the following description taken inconnection with the drawings, inwhich:

Fig. 1 is a sectional view ofa fractionating vessel taken in elevation, illustratingapreferred embodiment of the invention. r

Fig. 2 is' a sectional view taken on the line 2-2 ofFig.1.

Fig. 3 isa sectional view of a fractionating vessel takerf in elevation illustrating a modified form of the invention.

Fig. 51- is a sectional view taken on the line 4-4 Referring tofFigsh1 and 2 of 'the drawings, a vessel 1 is f shown'having a'vapor inlet 2 and a vapor, outlet 3'. A lineq is provided through which a coolingliquidmay be introduced into the upper I portion of the vessell and distributed over the upper portion of the vessel l by a spreader plate 5-. A line 6 is provided for withdrawing dephlegmated condensate from the bottom of the vessel. A plurality of oppositely inclined corrugated baffles 13 8-,"9 and Ill, "whose corrugations'run at adaptable to fractionators and" right angles to the direction of inclination of the baffles, are secured within inclined arcuate' bands l2, l3, l4 and I5, fitted snugly against the inner wall of the vessel I. The bafiles are-preferably perforated in'the valley of eachcorrugationand the lower edge of each baffle terminates in an overflow wall short of the opposed vessel'wall to form a gap therebetween to provide a passage for" the vapors. Due to the reversed relationofsuc cessive baflles these gaps occur on opposite sides of the vessel on adjacent baffles, thus providing", a zig-zag path for the upwardly rising vapors. Any desired number of bafiles may be employed. A sump or trap basin is provided in the upper portion of certain of the bafiles, as shown at [6;

from which a trapped liquid may beremoved through adrawoff line I8. 7 A v Referring now to Figs. 3 and 4 of the drawings, a vessel 20 is shown having a vapor inlet'2l and a vapor outlet 22, the latter being shielded by a protecting plate 26. A supply pipe 23, formed with a spray outlet 24, is provided through which a cooling liquid may be introduced into the vessel and distributed over the interior of the vessel. The dephlegmated condensate may be withdrawn from the bottom oithe vesselthrough'the line 25. A plurality of corrugated baffles 30,. 3i

and 32 are 'securedin arcuate bands 33,:f34f and 3.5, spaced throughout the interior offlthe vessel, the baffles being supported at anobligue arigleon the inner. wall of the vessel 20, asin thei first form oft-he invention. I I

The bafiles shown in'this embodiment are in general. similar to those shown in Figs, 1 and 2 and may be employed in any'desired. number, but in thissecond form of the invention each baffie except the lowermost one isp 'ovidedwith an overhanging ledge 40 constituting ,a part1: tion wall or platewhich depends into 'an appropriate sump or trap basin 4! formed, injtheupper portion of thenext succeeding'bafile. The plates 40 and the associated liquid filled sumps' constitute liquid seals which cause the rising vapors to pass through the openings in the bafiles 3G, 31,. etc., before reaching the vapor o'utlet 22. The trap basins M are shown as provided with outlet. pipes 35 and 38, leading out through .the wall of the Vessel 20 and through which'difierenti fractions maybe removed.

The main purpose of the: fractionating appa-f ratus described herein is to afford "a maximumr amount of 'contact'between the moving'vapor stream andthe continuously refluxing con'd'en sate, while permitting the accumulation andremoval of the fractional condensate and to provide a maximum of heat absorbing surfaces on the transverse bafile plates without increasing the over-all size of the fractionating chamber and bailles. The apparatus tends to efiect the smooth and uniform advancement of the vapors through the fractionating column, and to enable the enicient separation of the oil into the desired fractions. The invention avoids to a large degree the mechanical entrainment and advancement of liquid particles with the vapors and avoids mechanical inclusion and later solution of the lighter vaporous constituents with the down-flowing liquid. The invention thus effects a desirable sharp and close fractionation, such that the end point of each succeeding fraction is approximately the same or slightly less than the initial boiling point in the preceding fraction.

In the operation of the apparatus shown in Figs. 1 and 2 the vapors may be introduced into the lower portion of the vessel I through the line 2, the vapors moving across the space beneath the bafile H], where they pass upwardly through the gap left between the edges of the bafiles and the walls of the vessel. The vapors moving progressively upwardly through the vessel, thus move back and forth in a zig-zag path, until they reach the vapor outlet 3. As the vapors are advanced and cooled the volume thereof is reduced, due to the condensation being effected, and it is accordingly possible to space the upper baflles more closely together than the lower ones, as shown. This construction tends to maintain a relatively constant velocity of the vapors through the tower, thus tending further to balance the operation and to lengthen the path through which the vapors move without increasing the height of the tower.

A regulated amount of cooling material, preferably a portion of the condensate from the vapots emerging from the vessel I through the outlet line 3, is returned through the pipe 4 and distributed over the upper bafile l by means of the plate 5, the liquid dropping downwardly through the rising vapor stream. A certain amount of vaporization of the reflux material will be effected, as well as some condensation of the vapor by this contact between the relatively cool reflux liquid and the hotter vapor.

The corrugations in the baffles are formed of a depth sufllcient to maintain shallow pools of condensatein them at the angle at which the baffles are pitched. The liquid deposited on the batlles 1, 8, etc. cascades from pool to pool, due to the slope of the bafiles. There is also a slow passage of liquid through the small openings in the valleys of the corrugations, if these openings are employed, the size of these openings being preferably such asto effect a rather fast drippingor the flowing of a minute stream of liquid from each shallow pool. Finally, the surplus of liquid that overflows the lowermost corrugation of each baffle drops downwardly through the rising vapor stream onto the next succeeding baflle. At this time, due to the intimate and complete vapor and liquid contact, there will be a certain vaporization of the cooling liquid and condensation of the upwardly moving vapors.

The corrugated form of the baffles facilitates the transfer of heat from the vapors to the bafiles I and from the bailles to the liquid. The shallow pools of heated condensate serve to expose the liquid material in a manner for effectively reboiling the liquids, while the tortuous movement of the vapors back and forth across the chamber .and the contact thereof with the reflux Serve to bring the vapors into thorough contact with the liquid for effecting uniform fractionation.

The sump or trap basin l6 catches the overflow from the baffle above and the trapped material may be withdrawn, or such portion as desired, any surplus of material caught in this basin overflowing and cascading over the baflie 9, together with the other liquid undergoing reboiling. Any desirable number and arrangement of trap bafiles may be provided, depending upon the height of the fractionating vessel, the character of the vapors being fractionated and the number of fractions desired.

In the optional arrangement shown in Figs. 3 and 4 the trap basin at the lower edge of each baille seals the vapor passage and, with the construction disclosed, forces the vapors upwardly through the openings in the battles. The liquid, however, flows downwardly as in the first form of the invention, cascading over the corrugated bafiles and flowing through the successive liquid seals formed at the sumps 4|. In this form of the invention, the openings in the baffles 30, 3|, etc., or their equivalent, are necessary, whereas in the form of the invention, illustrated in Figs. 1 and 2, the openings may be omitted.

The form of the invention illustrated in Figs. 1 and 2 operates with very little pressure drop throughout the tower. This construction is therefore particularly adapted for towers subjected to a relatively high vacuum. The form of the invention shown in Figs. 3 and 4 has a substantial pressure drop through the tower, when constructed of the usual height and with the usual number of trays. This apparatus requires accurate construction and proportioning as the openings in the baflles are required to accommodate the entire volume of rising vapors. This form of the invention is particularly applicable to towers operated under pressure.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof as set forth in the appended claims.

I claim:

1. Apparatus for dephlegmating hydrocarbon oil vapor comprising a closed vessel having a lower vapor inlet and an upper vapor outlet, a liquid outlet adjacent the lower portion of the vessel, and downwardly sloping vertically spaced transversely corrugated baflles affixed to alternate side walls of the vessel, the lower free edges of the baflles terminating short of the opposed walls of the vessel for forming successive gaps between the lower free edges of said baffles and the walls of said vessel to provide a staggered vapor flow passage.

2. An apparatus for rectifying hydrocarbon vapors comprising an enclosed chamber having a lower vapor inlet and an upper vapor outlet, a liquid outlet at the lower portion thereof, a series of downwardly inclined staggered baflles projecting inwardly into said chamber from the side walls thereof intermediate said vapor inlet and said vapor outlet, each of said baflles being formed of thin material with vapor receiving recesses on the lower surfaces thereof for affording large vapor contact surfaces thereon and with liquid receiving pockets for condensed liquid on the upper surfaces thereof, said baffles being formed with unobstructed overflows at the lower edges thereof, the overflow of a preceding bafile discharging liquid onto the upper portion of a succeeding bafile.

3. Apparatus for rectifying hydrocarbon vapors comprising a vessel having a vapor inlet and a vapor outlet, a series of downwardly inclined bafiles in the vessel, successive baffles being alternately inclined in the opposite direction, corrugations in the baiiles extending at right angles to the direction of inclination of the baflles, successive baflles of said series being formed with depending lower edges and with basins adjacent their upper edges into which the depending edges of the next higher bafiles project.

4. Apparatus for fractionally condensing hydrocarbon oil vapors comprising a vessel having a vapor inlet and a vapor outlet, a series of downwardly inclined baflles in the vessel, successive baflies being alternately inclined in the opposite direction, corrugations in the baffles extending at right angles to the direction of inclination of the baffles, perforations in the valleys of the corrugations, a cooling liquid connection leading into the upper portion of the vessel, a spreader inside the vessel near the upper portion for distributing a cooling material over an upper baffle, successive baffles of said series being formed with depending lower edges and with basins adjacent their upper edges into which the depending edges of the next higher bafiles project and outlets provided for withdrawing liquid from certain of said basins.

5. In an apparatus for dephlegmating hydrocarbon oil vapors, an enclosed chamber formed with a vapor inlet and a vapor outlet for leading vapors upwardly through'said chamber, a liquid outlet in the lower portion of said chamber, and downwardly inclined staggered baflle plates extending acrossthe major portion of said chamber and terminating short of the opposed chamber walls to provide a staggered vapor flow passage,

' each said baffle plate including a series of transversely arranged corrugations constituting liquid receivingpockets on the upper surface thereof, from which liquid overflows from one pocket.

to another as it flows downwardly along the inclined baflle plate, and finally overflows from the lower end of the baffle plate and falls across the path of vapor flow, each said bafile plate also including a series of vapor receiving recesses on the under surface thereof for increasing the heat transfer from the vapor beneath the plate to the liquid above the plate.

6. In an apparatus for dephlegmating hydrocarbon oil vapors, an enclosed chamber formed with a vapor inlet and a vapor outlet for leading vapors upwardly through said chamber, a liquid outlet in the lower portion of said chamber, and downwardly inclined staggered baflle plates extending across the major portion of said chamber and terminating shortof the opposed chamber walls to provide a staggered vapor flow passage, each said baffle plate including a series of transversely arranged corrugations constituting liquid receiving pockets on the upper surface thereof, from which liquid overflows from one pocket to another as it flows downwardly along the inclined baffle plate, and finally overflows from the lower end of the baffle plate and falls across the path of vapor flow, said pockets being provided with restricted drain openings adjacent the lower portions thereof through which limited quantities of liquid flow and, also fall across the'path; of vapor flow, each said baflie plate also including a series of vapor receiving recesses on the under surface thereof for increasing the heat transfer from the vapor beneath the plate to the liquid above the plate. '7. Apparatus for rectifyingandfractionally condensing hydrocarbon vapors, comprising a closed vessel having a lower vapor inlet and an upper vapor outlet, a liquid outlet adjacent the lower portion of the vessel, a plurality of downwardly inclined baffle plates affixed to alternate side walls of the vessel intermediate the said vapor inlet and the said vapor outlet, the lower free edges of the baffles terminating short of the opposed walls of the vessel for forming staggered gaps therebetween to provide a tortuous vapor flow path, each of said baffies being formed with a plurality of comparatively shallow liquid retaining pockets for receiving condensed liquid on the upper surface thereof, from which liquid overflows from one pocket to another as it flows downwardly along the inclined bafiie plate, and finally overflows from the lower free edge of a superposed baffle and falls across the path of vapor flow onto the next succeeding baffle, each of said battles also including a series of vapor receiving recesses on the under surface thereof for increasing the heat transfer from the vapor beneath the baflle to the liquid above the baffle, certain of said baflles also being 5 formed with a comparatively deep liquid containing sump adjacent the side wall of the vessel, and a liquid offtake from said sump leading to the exterior of said chamber for side streamwithdrawal.

FRANK W. HALL.

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