US3162700A - Contactor for treating fluids - Google Patents

Description

J. D. IRONS CONTACTOR FOR TREATING FLUIQS Dec. z2, 1964 2 Sheets-Sheet 1 Filed May 25, 1961 INVENTOR.

L/e//a BY Dec. 22, 1964 J. D. iRoNs coNTAcToR FOR TREATING FLUIDS 2 Sheets-Sheet 2 Filed May 23, 1961 IWW, l Il l" Rm M5. m/ W fw La. mm Wf/ W, MMM,

United States Patent Oiiice .'idhh Patented Dec. 22, 1964 3,lo2,7tlti @UNTACTGR EUR TREA'EHNG FLlUiDd lleiery D.. Irons, Tulsa, Gitta., assigner to Union Tank Car Company, Chicago, ill., a corporation of New .lierse y Filed May 23, wat, Ser. No. ll2,lil4

4 Claims. (tCl. Zal-did) This invention relates in general te counter-current uid treating and handling operations such as moisture removal, scrubbing, absorption, fractionation and distillation and the like. It deals more specifically with apparatus for controlling the ow of ascending gas and descending liquid in a contacter.

It is an object of this invention to provide a new and improved counter-current contacter.

Another object is to provide a contacter which is simple in construction and less expensive than any similar equipment heretofore known.

Still another object is to provide a contacter having a series of superimposed contact zones wherein each zone functions independently of its relationship to adjoining zones.

Another object is to provide a contacter wherein the superimposed contacter trays deining contact zones therein are spaced and supported by axially aligned iluid downcomer means.

Another object is to provide structure including generally axially aligned inux and discharge control means arranged to direct descending liquid throughout a maximum portion of each contact zone.

Yet another object is to provide structure in each Contact zene facilitating the influx and discharge of the descending uid medium at generally axially aligned, angularly displaced inlets and outlets.

A further object is to provide a contacter including contact plate and downcomer arrangements which are identical in construction and may be assembled in superimposed relationship witheut regard to relative orientation.

The above and other objects are realized in accordance with the present invention by providing a new and improved contacter construction. Briefly, a typical counter current contact operation, in which moisture is purged from a moisture laden gas through intimate commingling of the gas with a fluid such as glycol, for example, normally involves providing a series of superimposed contact zones wherein a continuously descending stream of the liquid successively commingles with a continuously ascending stream of moisture laden gas. In each of the series of superimposed contact zones a separate and identical purging operation takes place in which fluid in the form of the descending liquid is circulated throughout the zone while the ascending gas passes upwardly through the circulating liquid and leaves a portion of its carried moisture behind as it rises and passes into the next contact zone. The descending liquid passes from top to bottom through the contacter in successive steps, by zone. Each zone includes means for receiving liquid from the zone immediately above and distributing it throughout the zone beforer discharging it into the zone immediately below. The ascending gas, on the other hand, rises through a number of widely distributed passage means in each zone and commingles with the circulating liquid as it passes upwardly therethrough and into the next zone wherein the identical operation is repeated.

The iniux of descending liquid to each zone and the discharge therefrom long with the effective circulation of the iluid throughout each contact zone is the primary concern of this invention. The latter is of great import,

of course, since the better circulation is the more intimate commingling of gas and liquid results. In essence, ascending gas is passing continuously through a layer of liquid as the liquid circulates throughout the zone. Inux and discharge of the liquid in each zone is effected from generally superimposed, axially aligned inlets and outlets and the liquid in passing from inlet to outlet is directed radially and angularly to effectively circulate throughout the greatest portion of each zone and consequently present the maximum surface area to the ascending gas. As a result, a highly eicient moisture removal operation is effected. It will be understood, of course, that a contact operation of the aforedescribed nature might be applied equally as Well to operations such as fractionation and distillation or the like, and the description of a contacter apparatus utilized in moisture removal is used merely as an example.

The invention, as to its organization, taken with further objects and advantages thereof, will best be underl stood by reference to the following description taken in connection with the accompanying drawings wherein several embodiments of the invention are shown:

FIGURE l is an elevational View of a counter-current contacter unit embodying this invention;

FIGURE 2 is an enlarged view in perspective of a portion of a contacter with parts broken away illustrating one of the contact zones;

FIGURE 3 is a sectional View in elevation Vof the structure ilustrated in FIGURE 2;

FIGURE 4 is a view similar to FIGURE 2 showing a modification of this invention;

FIGURE 5 is an enlarged plan view of a contact zoriie illustrating another embodiment of this invention; an

FIGURE 6 is a front elevation in partial section of the embodiment shown in FIGURE 5.

Referring now to FIGURE l, a counter-current contactor is illustrated generally at Iii. The contacter functions, in its instant application, to purge moisture laden gas of water vapor by treating the gas, in a series of superimposed contact zones, with a water attractive liquid such as glycol. Of course, it will be understood that other liquid chemicals having similar properties might be utilized. The gas ascends through a series of these contact zones while the liquid descends therethrough. Moisture laden liquid is removed from the contacter to be processed and recirculated and moisture free gas is taken off as a product of the operation.

As shown in FIGURE 1, the contacter lli) includes a vertically disposed tank er vessel 1l having a liquid inlet coudult I2 at its top and a liquid outlet conduit 13 at its base. Gas is introduced to the vessel lll through conduit ldadjacent its base and removed in substantially moisture free form through conduit l5 at the top of the vessel. A series of contact zones lo lie in superimposed relation within the vessel ll. Each zone is dened by substantially identical structure which facilitates the commingling and contact of glycol and moisture laden gas, for example.

FIGURES 2 and 3 illustrate ene embodiment of the Contact zone forming assemblies defining these zones. Each assembly in a contacter is substantially identical in construction and consequently only one such assembly is shown and described herein. Basically, each zone forming assembly includes means for receiving liquid from the assembly above and discharging it into the assembly below. Between influx and discharge the liquid is circulated around the zone such that it leaves at a point in general axial alignment with the point or port at which it entered. As the liquid circulates, moisture laden gas ascends through it land is removed of its moisture. Each zone assembly includes a tray 19 having an outside diameter substantially equal to the inside diameter of vessel 11 and secured thereto transversely of the axis of the vessel by conventional means such as welding. A fluid tight seal is established between the periphery of each tray 19 and the inner wall of the vessel 11. As perhaps best seen in FIGURE 3, risers 20 extend through the tray 19 at generally regularly spaced intervals therearound. The risers extend a predetermined distance above the surface of the tray 19 and each is provided with a bubble cap 21 over a corresponding riser and secured to the upper surface of the tray 19. Each bubble cap has a plurality of gas openings 22 around its periphery, the upper end of each gas opening being disposed slightly below the top of a corresponding riser 20. This relationship, as will be fully discussed hereinafter, prevents ascending gas from entering a contact zone without passing through a bath of descending liquid.

Seated in the center of each tray 19 is a hub 23. Each hub is identical in construction and includes a sleeve 24 having a transverse dividing wall 25 seated between its ends forming liquid inlet chamber 26 and outlet chamber 27. The hub receives a downcomer pipe 28 which is secured by welding for example, at its lower end to dividing wall 25. A port 29 of predetermined height is formed in the side of pipe 28 adjacent its lower edge while an inlet Weir 30, whose upper edge 31 extends higher than the port 29, is formed in the top of sleeve 24. This relationship is significant, as will hereinafter be discussed in detail, since it forms a liquid seal around por-t 29 and prevents gas from passing up the downcomer pipes. The upper end of downcomer pipe 28 is, of course, adapted to extend up through the tray 19 in the zone forming assembly immediately above. This is best illustrated by the lower of the two downcomer pipes 28 shown in each of the FIGURES 2 and 3, this pipe extending through a centrally disposed hole in tray 19 and secured thereto in fluid sealing relationship by conventional means.

Each downcomer pipe 23 is adapted to extend upwardly into a corresponding chamber 27 to a predetermined height above the tray, this height establishing the fluid level on the tray and permitting overllow to pass down the pipe in-to the next contact zone assembly 16. Liquid gains access to chamber 27 and the upper end of the pipe 28 through inlet port 35, which, as will be seen in FIGURE 2, is angularly displaced from weir upon the circumference of sleeve 24. A large liquid dam 36 separates the angularly displaced weir 30 and inlet port 35 and is secured to the upper surface of tray 19 and the outer surface of sleeve 24 as Well as the inner surface of vessel 11 by conventional means, which might be welding. A series of small liquid dams 37 extend radially of the sleeve 24 to a position short of the periphery of trays 19. The dams 37 are generally regularly spaced about the sleeve.

The liquid medium, which in this case is glycol, as has been pointed out, descends into each successive contact zone assembly from the assembly above through a downcomer pipe 28. As will be seen where the arrows L designate the general path of .the downcorning or descending fluid, it enters the upper chamber 26 of hub assembly 23 and spills over the lower edge 31 of weir 30 on to the upper surface of tray 19. Because the upper edge of outlet port 29 on downcomer pipe 28 is lower than the lower edge 31 of the weir 30, a iluid seal is established around the outlet port 29. As has been previously explained, gas is consequently not permitted to escape up the downcomer pipe.

The iluid, after descending from Weir 30 to the tray 19 as indicated by the arrows L, circulates about the upper surface of the tray in a clockwise direction overlying and surrounding the riser bubble caps 21 and nally passing through the inlet port in sleeve 24 into chamber 27 and down through the lower downcomer pipe 28, as best illustrated in FIGURE 3.

The clockwise flow of fluid is induced by the relationship of the large darn 36 to the inlet Weir 30 and the outlet port 35. It will be seen that all of the entering lluid L must completely circumnavigate the sleeve 24 before reaching port 35 and subsequently the lower downcomer pipe 28. Small liquid dams 37 in the meantime prevent the bulk of the iluid from taking the shortest path around the sleeve 24, that is the path closest to the sleeve. The bulk of the circumnavigating uid is forced to the outside of the tray 19 and consequently travels over the largest percentage of the tray.

The depth of the duid on the tray 19 is controlled by the distance which lower downcomer pipe 2S extends above it, as will be readily seen in FIGURE 3. Here, due to the relationship in height between this extension of downcomer pipe 28 and the height of gas openings 22 in bubble caps 21, the fluid level is established such that it extends above the gas openings. Hence, gas must pass through the liquid bath to escape the bubble caps.

While the liquid L is descending in the manner hereinbefore described, the ascending moisture laden gas, as shown by arrows G, passes up through risers 20 and then down and out through gas outlets 22 into the contact zone where it commingles with the eliiciently circulating liquid and is purged of a substantial amount of its moisture. The gas then rises from the surface of the liquid on tray 19 and passes upwardly through the risers in the contact zone assembly immediately above where the process is repeated.

FIGURE 4 illustrates another embodiment of this invention. In essence, a multiple inlet Weir and inlet port arrangement is provided in each hub assembly. In each weir and inlet port pair, the Weir is radially spaced from the port. Each pair is isolated from the other pairs into what actually is a sub-zone of the basic contact zone. In addition, FIGURE 4 illustrates a dilerent type of tray, in this instance a sieve type tray 119. The sieve type tray has a plurality of line, sieve holes extending therethrough. The holes 120 are fine enough to permit the passage of gas upwardly therethrough while being small enough to prevent passage of the circulating liquid in the opposite direction.

The embodiment illustrated in FIGURE 4 more specifically includes a hub 123. The hub comprises a sleeve 124 having a transverse dividing wall 125 seated between its ends forming liquid inlet chamber 126 and outlet chamber 127. Hub 123 further includes a pair of downcomer pipes 128 identical in construction to pipes 28 illustrated and described in the description of the first embodiment. In line with this, a port 129 of predetermined height is formed in the side of each pipe 128 adjacent its lower edge. Spaced around the upper edge of sleeve 124 are a series of generally regularly spaced inlet weirs 130, whose upper edges 131 extend higher than the port 129.

Each downcomer pipe 128 extends upwardly into a corresponding discharge chamber 127 to a predetermined height above the tray 119, this height establishing the iluid level on the tray permitting overflow to pass down the pipe into the next contact zone assembly. Liquid gains access to outlet chamber 127 through a plurality of generally regularly spaced outlet ports 135, which as will be seen in FIGURE 4, are angularly displaced from the weirs upon the circumference of the sleeve 124. A large liquid dam 136 separates adjoining pairs of angularly displaced inlet weirs 30 and discharge ports 35. The large dams are secured to the upper surface of the tray 119 and the outer surface of the sleeve 124 as well as the inner wall of vessel 11 by conventional means, such as welding. Alternating with the large dams are a series of small dams 137 which extend radially of the sleeve 124 to a position short of the inner wall of the vessel 11. The dams 137 are positioned between the inlet weir 130 and outlet port 135 of each pair of inlet weirs 130 and outlet ports 135.

In this contact zone assembly the path of the descending liquid, as illustrated by the arrows L, leads into three separate contact Zones which might de described as sub- Zones. The operation of each is identical. Fluid spills over the lower edges 131 of inlet weirs 130 onto the upper surface of tray H9. Due to the fact that the upper edge of port 1.29, on downcomer pipe 1125, is lower than the lower edges i3d of the weirs 130, a duid seal is established around the outlet port l29, and gas is consequently not permitted to escape up the downcomer pipe to short circuit the contact process.

The fluid, after descending from each of the weirs 130 to the tray 119 as indicated by the arrows L, circulates about the corresponding small dams 137 and passes out of the outlet port ILSS and down the lower downcomer pipe H8. As in the embodiment illustrated in FIGURES l through 3, the depth of the fluid on the tray 120 is controlled by the distance which lower downcomer pipe 12S extends above it.

As the fluid descends in the foregoing manner, the ascending moisture laden gas passes up through the minute sieve holes l2@ in the tray Trl@ into one or the other of the contact sub-zones Where it commingles with the efficiently circulating liquid and is purged of its moisture. The gas then rises in a well known manner from the surface of the liquid on tray M9 and passes upwardly through the sieve holes 119 in the Contact tray immediately yabove where the process is repeated.

Illustrated in FIGURES 5 and 6 is another embodiment of this invention. ln this embodiment a Contact tray 219 substantially identical to the tray illustrated in FIGURES l through 3 is shown. The tray has a series of risers 22d generally regularly spaced on its surface and bubble caps 22]; having gas outlets 222 around their circumference overlie the risers and are secured to the upper surface of the tray. A lesser number of risers and bubble caps are illustrated in this embodiment than in the embodiment of FIGURES 1 through 3, but the effect is substantially the same, the tray construction, per se, forming no part of this invention.

A hub 223 is seated in the center of each tray Zit). Each hub is identical in construction and includes a generally rectangular sleeve 224 having a transverse dividing wall 225 seated between its upper and lower ends and forming inlet chamber 226 and outlet chamber 227. A downcomer pipet228 is secured by welding or the like at its lower end to each dividing wall 22d. A port 229 of predetermined height is formed in the side of pipe 22S adjacent its lower edge while inlet weirs 23d, whose upper edges Ziii extend higher than the upper edge of .the port 229 are formed in the top of sleeve 22d. The upper end of each downcomer pipe 228 is adapted to extend upwardly through a corresponding tray 219 into the liquid outlet chamber 227 of the zone forming assembly immediately above.

As pointed out in the description of the embodiment of FIGURES l through 3, each downcomer pipe 228 is adapted to extend upwardly into a corresponding chamber 227 to a predetermined height above the tray, this height establishing the iiuid level on the tray and permitting overiiow to pass down the pipe into the next contact zone assembly. Liquid enters the chamber 227 and consequently the upper end of pipe 228 through outlet ports 235. A pair of large liquid dams 236 separate the inlet weirs 230 and outlet ports 23S such that in each such pair the inlet Weir 23h and the outlet port 235 aredisposed on opposite sides of the rectangular sleeve 224. The large dams 235 are secured to the upper surface of tray 219 and the outer surface of sleeve 224 as well as the inner Wall of vessel 11 by conventional means which might be welding.

In a manner substantially similar to that illustrated and described in the embodiment shown in FIGURES 1 through 3, the liquid medium descends into each successive c-ontact Zone from the assembly above through a downcomer pipe 22S. The liquid, as indicated by the arrows L, enters the upper chamber 226 and spills over the lower edge 2.3i of the inlet weirs onto the upper surface of tray 219. Again due to the fact that the upper edge of port 229 on downcomer pipe 228 is lower than the lower edges 231 of the weirs 23d, a uid seal is established around the outlet port 229 and gas is not permitted to escape up the downcomer pipe.

As seen best in FIGURE 5, the fluid, after descending from the weirs 23) onto the tray 219, circulates about the upper surface of the tray in `a counter clockwise direction overlying and surrounding the bubble caps 221 and iinally passing through the outlet ports 235 in sleeve 224 and down through the lower downcomer pipe 228. The counter clockwise flow of fluid is induced by the relationship of the large dams 236 to the inlet weirs 23) and the outlet ports 235. In effect two contact sub-zones are formed and the iluid in each of these two sub-zones must circumnavigate one half of the elongated rectangular sleeve 224 before reaching a corresponding outlet port 23S and subsequently the lower downcomer pipe 22S. The extended ends of the rectangular sleeve 224.L prevent the fluid from tak-ing a path which does not contact and envelope the bubble caps. The bulk ofthe circumnavigating Huid is forced to pass over each of the risers and caps and in doing so covers the greatest portion of the tray 219. The depth of the fluid on the tray 2119 is controlled by the distance which lower downcomer pipe extends above it. ln effect, as has been previously pointed out, the iiuid level is then established above the height of the `gas openings 222 in bubble caps 221.

In the manner of each of the irst two embodiments described, as the liquid is descending the ascending moisture Vladen gas passes up through risers 22d and out through gas outlets 222 into the contact Zone where it commingles with circulating liquid and is purged of its moisture. The gas then passes upwardly through the risers in the contact zone assembly immediately above Where the process is repeated.

In each embodiment illustrated and described it will be seen that the contact zone assemblies include trays (19, M9 and 219). In the embodiments illustrated in FIG- URES 1 through 3, 5 and 6, these trays are of the well known bubble cap type. In contrast, the embodiment shown in FIGURE 4 utilizes a sieve type tray; also a. well known construction. A number of other tray types are frequently utilized in contactors of this general type; such as Valve type trays, grid type trays and cascade type trays. All of these `are conventional and it will be readily understood that they might be utilized without departing from the theme of the invention. The bubble type tray land the `sieve type tray are illustrated only as examples and form, in detail, no part of the invention.

Each of the embodiments of the hub and downcomer :arrangement illustrated and described distribute descending liquid throughout the contact Zones in substantially the same manner. In essence, fluid is received in each Zone at `an inlet port or Weir raised above the zone delineating tray. Fluid descends to the surface of the tnay at this point and then must pass generally circumferenti'ally of the hub to a corresponding outlet port or ports. In doing so it covers, in the single complete contact Zone or in a series of `adjoining sub-contact zones, the greatest portion of the contact tray. In reaching its discharge port the bulk of the huid has consequently passed over the entire tray surface or entire subzone portion of the tray `surface and returned to the outlet means. These outlet means lare at tray level in general axial alignment with the inlet means above them.

ln effect then, the fluid cornes into the contact zone at a raised level, passes down to the tray at a predetermined point or points, travels clockwise or counter clockwise around the tray, which ever the case may be, and is discharged from the contact zone iat a point beneath the inlet port vand Isubstantially in axial alignment therewith. It will be understood that the hubs 1 and downcomer pipes described might be located along the central axis of the contactor vessel and trays, as illustrated, but they might also be located in alignment along any axis perpendicular to the central axis. Of importance is that the structure forming liquid inlet and outlet control means is disposed along substantially the same axis in superimposed relationship and means are provided for distributing the iluid throughout the contact zones as it passes between inlet and outlet.

What has been devised is a downcomer, hub and tray combination which can be assembled Without regard to relationship to the adjoining trays, downcomers and hubs. The inux and discharge of the descending liquid is not dependent upon orientation of the adjoining superimposed trays as it has in most eontactors heretofore known. Each contactor zone is a completely independent entity. The result is a contactor which is substantially less expensive to build than any |heretofore utilized. Because the con-struction of each zone is identical in addition to being simple, .a standardized assortment of parts can `be utilized in each zone.

In line with the simplicity of the construction, the hubs `and downcomers provide separation and support means between the adjoining superimposed trays. In doing such, they perform the dual function of directing fluid distribution and spacing and supporting the trays with the fewest number of parts and the simplest construction.

The operating efficiency of each of the contact zones illustrated is substantially higher than contactors heretofore known, whether the single contact zone be utilized or a sub-zone type principle as illustrated in FIGURE 4. The circulating luid is forced to cover a maximum portion of the contact tray surface and consequently the contact zone. This results in a highly eicient commingling or contact of the ascending gas and the descending liquid. lt will be easy to understand that the result is an extremely eicient and consequently improved contactor process. As applied to the example used in describing this invention, moisture removal is effected -With maximum eiciency and minimum cost.

While several embodiments of this invention have been described, it is understood that variations and improvements might be made therein Without departing from the theme of the invention and it is intended to cover in the appended claims all such modifications and improvements as fall within the true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of the United States is:

1. An assembly for defining a contact zone in a countercurrent contactor comprising a contactor tray, a hub mounted on said tray on the central axis thereof, horizontally disposed partition means in said hub defining a liquid inlet chamber above said partition means and a liquid outlet chamber below said partition means in axial alignment with said inlet chamber, liquid downcomer means extending into said inlet chamber, liquid downcomer means extending out of said outlet chamber, a liquid inlet means in said inlet chamber for depositing liquid on said tray adjacent said hub and a liquid outlet means in said outlet chamber for receiving liquid from said tray, said inlet means and said outlet means being angularly displaced about said axis, a relatively large liquid dam mounted on said tray and extending between said hub and the periphery of said tray, said relatively large liquid dam adapted to prevent liquid communication between said inlet means and said outlet means in,

one direction around said hub, a relatively small liquid dam mounted on said tray, said relatively small liquid dam extending into engagement with said hub in spaced relationship with said large liquid dam, said small liquid dam adapted to force the bulk of the descending liquid to seek a path near the periphery of said tray in passing between said inlet means and said outlet means.

2. The assembly of claim 1 further characterized in that said inlet chamber includes a plurality of liquid inlet means and said outlet chamber includes a plurality of liquid outlet means, a plurality of said large liquid dams mounted on said tray between corresponding inlet land outlet means, and a plurality of said small liquid dams mounted on said tray in spaced relationship therewith.

3. In combination in a counter-current contactor, an elongated vessel, a plurality of trays in said vessel extending transversely thereof and dening contact zones, each of said tnays being substantially radially symmetrical whereby trays may be superimposed upon each other in any angularly oriented relationship, a hub mounted on each of said trays, said hubs lying generally in axial alignment in said vessel, a liquid inlet chamber in each hub, a liquid outlet chamber in each hub in axial alignment with said inlet chamber, liquid downcomer means extending into each inlet chamber from the zone immediately above, liquid downcomer means extending out of each outlet chamber into the zone immediately below, liquid inlet means in each of said chambers for depositing liquid on a corresponding tray adjacent said hub, liquid outlet means in each of said outlet chambers for receiving liquid from a corresponding tray, said inlet and outlet means being angularly displaced about said axis, a relatively small liquid dam on the surface of each of said trays land extending outwardly from a corresponding hub, the liquid descending from each inlet means onto a corresponding tray and moving around said hub to a corresponding outlet means, said relatively small liquid dams tending to lforce the bulk of said liquid to seek a path near the periphery of said tray, and a relatively large liquid dam mounted on each of said trays between said hub and said vessel, each of said relatively large liquid dams extending between corresponding radially displaced inlet and outlet means to prevent liquid communication therebetween in one direction about said hubs.

4. The combination of claim 3 further characterized in that each of said hubs comprises an elongated rectangular sleeve having a transversely disposed plate between its ends forming said inlet chamber above said plate and said outlet chamber below said plate.

References Cited in the le of this patent UNITED STATES PATENTS 1,688,515 Baker et al Oct. 23, 1928 1,738,870 Cox et al Dec. 10, 1929 1,848,462 Corbett Mar. 8, 1932 2,202,071 Van Dongen et al May 28, 1940 2,241,114 Brunjes May 6, 1941 2,327,993 Bragg Aug. 31, 1943 2,651,512 Voleau Sept. 8, 1953 2,810,563 Fleming Oct. 22, 1957 2,812,827 Worley et al Nov. 12, 1957 FOREIGN PATENTS 655,087 Germany Jan. 8, 1938 731,667 Great Britain June 15, 1955 862,598 Germany Jan. 12, 1953

Claims (1)

1. AN ASSEMBLY FOR DEFINING A CONTACT ZONE IN A COUNTERCURRENT CONTACTOR COMPRISING A CONTACTOR TRAY, A HUB MOUNTED ON SAID TRAY ON THE CENTRAL AXIS THEREOF, HORIZONTALLY DISPOSED PARITION MEANS IN SAID HUB DEFINING A LIQUID INLET CHAMBER ABOVE SAID PARTITION MEANS AND A LIQUID OUTLET CHAMBER BELOW SAID PARTITION MEANS IN AXIAL ALIIGNMENT WITH SAID INLET CHAMBER, LIQUID DOWNCOMER MEANS EXTENDING INTO SAID INLET CHAMBER, LIQUID DOWNCOMER MEANS EXTENDING OUT OF SAID OUTLET CHAMBER, A LIQUID INLET MEANS IN SAID INLET CHAMBER FOR DEPOSITING LIQUID ON SAID TRAY ADJACENT SAID HUB AND A LIQUID OUTLET MEANS IN SAID OUTLET CHAMBER FOR RECEIVING LIQUID FROM SAID TRAY, SAID INLET MEANS AND SAID OUTLET MEANS BEING ANGULARLY DISPLACED ABOUT SAID AXIS, A RELATIVELY LARGE LIQUID DAM MOUNTED ON SAID TRAY AND EXTENDING BETWEEN SAID HUB AND THE PERIPHERY OF SAID TRAY, SAID RELATIVELY LARGE LIQUID DAM ADAPTED TO PREVENT LIWUID COMMUNICATION BETWEEN SAID INLET MEANS AND SAID OUTLET MEANS IN ONE DIRECTION AROUND SAID HUB, A RELATIVELY SMALL LIQUID DAM MOUNTED ON SAID TRAY, SAID RELATIVELY SMALL LIQUID DAM EXTENDING INTO ENGAGEMENT WITH SAID HUB IN SPACED RELATIONSHIP WITH SAID LARGE LIQUID DAM, SAID SMALL LIQUID DAM ADAPTED TO FORCE THE BULK OF THE DESCENDING A LIQUID TO SEEK A PATH NEAR THE PERIPHERY OF SAID TRAY IN PASSING BETWEEN SAID INLET MEANS AND SAID OUTLET MEANS.

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