US3015545A - Apparatus for effecting fluid-fluid contact - Google Patents

Description

Jan- 2, 1962 H. H. rGRQSS ETAL 3,015,545

APPARATUS FOR EFFECTING FLUID-FLUID CONTACT Filed March 26, 1959 United States Patent hice Patented Jan. 2, 1962 are Filed Mar. 26, 1959, Ser. No. 802,203 4 Claims. (Cl. 23-2705) This invention relates to an apparatus for eifecting duid-fluid contact. More particularly, this invention relates to an apparatus for effecting liuid-iluid Contact between two immiscible fluids. Still more particularly, this invention relates to an apparatus for electing liquidliquid contact, such as countercurrent liquid-liquid contact, between two at least partially irnmiscible liquids.

In U.S. Patent 2,601,674 there is disclosed an apparatus described as a rotating disc contactor particularly suitable for effecting liquid-liquid contact between two immiscible liquids. As described in the above-identied patent a rotating disc contactor comprises a stationary tube or shell of which the part forming the actual contacting zone is subdivided into a plurality of compat*- ments, preferably substantially identical in size and shape, by stationary annular baffles or rings having central openings. Further, there are rotor discs, one in each compartment, xed on a rotor shaft co-axial with the stationary tube, the discs being located approximately half way between the stationary bales and having a diameter smaller than the diameter of the openings in the stator bafes. The liquids to be contacted are fed into the contactor to traverse these several compartments successfully, either in concurrent ow or in countercurrent flow with respect to one another. When used for counter current flow of liquids, the tube, contacting zone, is at least partially upright, e.g. vertical, and the liquids are of diierent densities; this results in the formation of two liquid phases of different densities which traverse these successive compartments in opposite directions. The rotation of the rotor discs imparts further movement to the liquids, causing intimate contacting.

It is an object of this invention to provide an improved rotating disc contactor.

Another object of this invention is to provide in a unitary apparatus a rotating disc contactor and a settling zone for use therewith to improve the fractionation operation and the separation, after contacting, of one liquid from another liquid, both liquids being at least partially immiscible with respect to each other.

Yet another object of this invention is to provide an improved apparatus, and method employing the same, for eliecting the solvent refining of petroleum such as lubricating oils, gas oils and the like.

Still another object of this invention is to provide an improved method and apparatus for effecting furfural solvent refining of petroleum fractions, such as lubricating oil fractions, gas oil fractions and the like.

How these and other objects are achieved will become apparent in the light of the accompanying disclosure made With reference to the drawing wherein there is schematically illustrated in partial cross section an apparatus for effecting fluid-fluid contacting in accordance with this invention. In at least one embodiment of the practice of this invention at least one of the foregoing objects will be achieved.

In accordance with this invention an improved apparatus for effecting fluid-fluid contact is obtained by incorporating in a unitary integral structure in combination with a rotating disc contactor a settling zone in such a manner that the rotating disc contactor is superimposed on the settling zone in direct, open duid communication therewith. Still further, in accordance with this invention in combination with the rotating disc contactor there is provided a settling zone positioned beneath the lowermost rotor and stator of the rotating disc contacter or contacting zone portion of the apparatus of this invention wherein the settling zone is provided with two fluid turbulence control means, such as screens or grids or nests of Raschig rings, to reduce and/or eliminate uid turbulence of uids passing therethrough. Positioned within this settling zone, intermediate the fluid turbulence control means is a fluid separator effective for the separation of a selected lluid stream or fluid from the settling zone. There is also provided within the settling zone, preferably directly beneath the duid separator, means for reintroducing and distributing tiuid within the settling zone, the fluid being reintroduced and distributed within the settling zone being the selected fluid phase previously removed from the settling zone by means of the uid separator after having been cooled-externally of the rotating disc contactor and superimposed contiguous settling zone and reintroduced into the settling zone via said liuid distributing means.

As disclosed in U.S 2,601,674, the disclosures of which are herein incorporated and made part of this disclosure, the rotating disc contacter or contacting zone portion of the unitary apparatus of this invention comprises an outer shell which should, when countercurrent extraction is to be practiced, be at least partially upright, e.g. vertical; preferably it is circular in cross section and lhas cylindrical walls. This shell or column in the contacting zone portion lthereof has fitted within it a series of annular, stationary, transverse stator baies extending from the shell wall radially inwardly to a central opening, thereby dividing the shell into a-series of compartments in communication with one another. The stator battles are preferably imperforate, except for the central opening, and are at or substantially so, whereby each bale has its substantially plane surfaces perpendicular to the shaft axis. The use of stator baffles or other outlines, e.g. frusto-conical surfaces of revolution, is possible. They may be permanently lixed to the shell Wall or removably mounted in any desired manner, and spaced axially with respect to the shell. The intervals between the bales, i.e. the depths of the compartments, may be uniform or may be varied in certain cases, as to take care of peak liquid loads. These stator bales are provided throughout the part of the shell that is to serve as the contacting or extraction zone portion thereof. Liquid inlet discharge ports are provided at suitable points, e.g. at the ends of the shell, the contacting zone being in the upper or one end of the shell and the settling zone being at the lower or other end of the shell.

A rotor shaft is rotatably mounted substantially coaxially within the contacting zone, and is provided with suitable drive means for rotation at a high speed, such as a speed in the range l02000 r.p.m. The rotor shaft extends through the openings inthe stator battles, and

carries a plurality of rotor discs or baffles arranged so that there is one rotor baille within each compartment, approximately midway between adjacent set of stator baffles. While at discs are preferred, other surfaces of revolution may be used. When, as in the embodiment illustrated in the drawing, a cylindrical shell is used and the stator baffles are of equal dimensions, the rotor baffles are all of lesser diameter than the diameter of the openings in the stator battles. When the stators are not all of the same size they may be arranged with openings becoming progressively larger toward one end, thereby permitting free movement of the shaft and the rotor bales through these openings.

Other features of the rotating disc contactor or contacting zone portion of the structure of this invention which improve liquid-liquid mixing include the relative dimensions of the shell and rotor baffles. Best results are obtainable when the ratio of the internal diameter of the shell to the diameterof the rotor bailles is from about 1.5 to and including about 3.0. Also, best results are obtainable when the ratio of the internal diameter of the shell to the axial interval between the batlles is from about 2V to and including about 8. Still another feature,

' the rotor bailles and stator bailles are preferably both formed of comparatively thin, sheet material, eg. metal or plastic, withoutirregularities, ribs, flanges or the like, thereby providing each of these bailles with two substantially smooth surfaces.

Beneath the lowermost stator and rotor and in open and direct fluid communication with the contacting zone in accordance with this invention is the settling zone. As clearly illustrated in the accompanying drawing, the contacting zone is superimposed upon the settling zone. The settling zone is provided with grids or nests of Raschig rings to reduce fluid turbulence in the upper portion thereof directly beneath the contacting zone. Beneath this upper grid or fluid turbulence control zone is means for effecting the separation and withdrawal of a selected liquid phase, such as a more dense liquid phase when two at least partially immiscible liquids of dilferent densities are being contacted within the contacting zone. The selected liquid phase is withdrawn from the settling zone, cooled and then reintroduced into the settling zone via a fluid distributing means at a position therein beneath the selected iluid separator means. As a result of cooling the withdrawn selected liquid'phase there tends to be precipitated or sprung from the cooled separated selected liquid phase an additional amount of the other liquid phase immiscible therewith, both of these liquid phases being reintroduced into the settling zone and distributed therein. Beneath the distributing means there is provided a second grid or nest of Raschig rings to eliminate fluid turbulence in the lluid passing therethrough within the lower portion of the settling zone.

The apparatus of this invention may be employed for contacting liquids, either concurrently or countercurrently. In countercurrent contacting the liquid to be separated may be passed in countercurrent contact to a single solvent or a solvent mixture admitted at the upper end of the apparatus; the liquid to be separated may also be subjected to double countercurrent contact, i.e. extracted with two partially immiscible solvents which are caused to flow countercurrently to one another by introduction into the contacting zone at-spaced points, the liquid to be separated being introduced either with one of the solvents or at a point intermediate the point of introduction of the two solvents.

The apparatus of this invention is further illustrated in the accompanying drawing. Referring now to the drawing which schematically illustrates the lluid-iluid contacting apparatus in accordance with this invention, there is illustrated a closed vertical column of circular cross section and cylindrical shape supported at its lower end by skirt 11 and provided with a bearing or journal 12 at its upper end to receive an axial rotor shaft 14. Means, not shown, are also provided for the rotation of shaft 14. The bottom end of shaft 14 is supported for rotation by bearing and bearing support 13. A plurality of circular, imperforate baflles 15 made of thin, flat sheet metal are xed to the rotor shaft for rotation therewith with their plane surfaces perpendicular to the shaft axis. The inner wall of the column is equipped with annular horizontal stator rings 16 likewise made of thin, fiat sheet metal, but having circular central openings concentric with the rotor bailles and shaft; they are arranged perpendicular to the shaft axis and are located so that they are approximately in the centers of the spaces between adajcent rotor bales. The stator battles subdivide the column into a vertical series of compartment, the height of which is determined by the vertical interval between bailles. This interval may be uniform throughout the height of the contacting zone but may, if desired, be non-uniform. In accordance with one embodiment of the apparatus in accordance with this inventionl the inner diameter or opening of the stators is greater than the diameter of the rotor battles whereby it is possible to insert the rotor assembly consisting of the rotor shaft and rotor battles through the openings in the stators and, if necessary, to remove this assembly after removing the top end of the column.

The stators 15 are mounted only in the central part or contacting zone of the column 10 leaving settling zones at both ends. Inlet ports 18 are provided for the admission of heavier and lighter liquids, outlet ports 19 are provided for the discharge of ralinate and extract and recycle ports are provided for the recycle of contacted liquids within column 10.

Fluid turbulence cofntrol lmeans or grids 21 are provided within the contacting Zone just above the bearing support 13 and just beneath the lowermost rotor 15 and lowermost stator 16. Fluid turbulence control means 21 serves to reduce or eliminate fluid turbulence within the uids llowing therethrough in either direction. 'Positioned be meath bearing support 13 are means for removing a selected tluid phase, such as the heavier liquid' phase, from the two immiscible fluids undergoing contactV within the contacting zone of column 10. Means for separating the selected liquid phase comprises a plate 22 provided with risers 24 therethrough and a large central riser 27 with a baffle 25 directly beneath the opening and a -baflle 26 being provided at the upper end of this central riser. Fluid withdrawal means or ring inlet 2,8 positioned just above plate 22 but beneath the tops of risers 24 and 27 is for the withdrawal of the heavier liquid phase which tends to collect beneath the top of risers 24 and plate 22.

Fluid distributing means or ring sparger 29 is provided directly beneath plate 22 for the discharge of the selected iluid phase withdrawn from the column 10 via means 23 and subsequently introduced into column 10 via means 29. Located beneath means 29 is another iluid turbulence controlprneans or grids 30 to reduce or eliminate ttluid turbulence in the fluid moving therethrough. The interval within column 10 between iluid turbulence control means 21 and 30 serves as a separating zone. As indicated in the drawing additional iluid turbulence control means or grids 30 are also desirably located within column 10 in the upper portion thereof preferablyabove the uppermost point of fluid entry and above the uppermost rotor 15 and stator 16.

Illustrative of this invention as embodied in a petroleum refining operation wherein liquid furfural is employed to solvent refine a petroleum fraction such as a gas oil, a lubricating oil or a catalytic cycle gas oil, liquid furfural is introduced into column 10 via line 32 through inlet 18. Simultaneously the petroleum fraction undergoing treatment is introduced into column 10 via line 34 and oil inlet 1=8. As indicated in the drawing alternate inlets 18 are also provided for the introduction of oil into column 10 at other locations. While liquid furfural and the oil are simultaneously introduced into column 10 rotor shaft 14 together withV rotors 15 are rotated at a suitable speed within column 10. As a result of the rotation of shaft 14 and rotors 15 within column 10 and as the oil and furfural llows counter-currently therethrough intimate mixing between furfural and oil takes place. lThe resulting refined oil as it moves upwardly within column 10 and through grids 30 is recovered from the upper end of column 10 via outlet 19 and line 35. rI'he refined oil or ranate mix thus recovered is then passed to suitable means for the recovery of solvent therefrom.

Liquid furfural, being the heavier phase, moves downwardly within column 10 and tends to collect above plate 22 as a separate phase. This separate liquid furfural phase is removed via iluid withdrawal means 28 and passed via line 36, pump 38 and line 39 through cooler 40 wherein the temperature of thepwithdrawn furfural phase is reduced, thereby tending to spring or precipitatetherefrom additional oil. The resulting admixture of cooled liquid furfural and precipitated oil is reintroduced into column via line 41 and ring sparger 29. if desired, as indicated in the drawing, the resulting cooled liquid furfural together with precipitated oil can be reintroduced into column 10 via line 42 and recycle inlet 20. Column 10 is also provided with means for withdrawal of -iiuid via recycle outlet and line 44 for admixture with the liquid furfural phase withdrawn from column 10 via means 2S and line 36. Positioned above and below fluid withdrawal means 28 and iluid distributing means 29, respectively, are uid turbulence control means or grids 21 and 30. The resulting liquid furfural phase or extract mix is withdrawn from column 10 via outlet 19 and line 45 for the separate recovery of furfural and oil therefrom. y

As will be apparent to those skilled in the art many modications, changes and alterations are possible in the practice of this invention without departing from the spirit or scope thereof.

We claim:

l. An operable system suitable for effecting fluidiiuid contact between two irrimiscible uid phases comprising in combination:

an elongated vertical container,

a plurality of vertically spaced disc-shaped rotors rotatably disposed and axially supported within said container,

a first permeable turbulence control means disposed at an intermediate position within said container below the lowermost of said rotors,

means below said lirst turbulence control means for withdrawal of a selected uid phase from said container,

means for cooling withdrawn selected uid phase,

means for reintrodncing cooled selected fluid phase into said container below said means for withdrawal of a selected uid phase,

a second permeable turbulence control means disposed within said container below said means for reintroducing cooled selected fluid phase, said irst turbulence control means and said second turbulence control means delimiting a separating zone in the lower portion of said container,

a first outlet from said container positioned above the uppermost of said rotors,

a second outlet from said container positioned below said second turbulence control means,

a first inlet to said container positioned below said first outlet and above the uppermost of said rotors,

and a second inlet to said container positioned intermediate said irst inlet and said rst turbulence control means.

2. An operable system for eifecting counter-current liquid-liquid contact which comprises in combination:

an elongated, vertically disposed contacting zone and a vertically disposed settling zone, said vertically disposed contacting zone being axially superimposed upon said settling zone and in open uid communication therewith,

rotors axially disposed within said contacting zone,

stators vertically disposed within said contacting zone in rotor-stator relationship with respect to said rotors such that said rotors are positioned within said contacting zone intermediate said stators,

means supporting said rotors for rotation within said contacting zone,

a iirst permeable turbulence control means disposed intermediate said contacting zone and said settling zone,

means below said rst turbulence control means for withdrawal of a selected liquid phase from said settling zone,

means for cooling withdrawn selected liquid phase,

-means for reintroducing cooled selected liquid phase into said settling zone below said means for withdrawal of a selected liquid phase,

a second permeable turbulence control means disposed below said means for reintroducing cooled selected fluid phase, said iirst turbulence control means and said vsecond turbulence control means delimiting a separating zone in said settling zone.

an outlet from said contacting zone positioned above the uppermost of said rotors,

an outlet from said settling zone positioned below said second turbulence ycontrol means,

'a rst inlet to said contacting zone positioned below said outlet from said contacting zone and above the uppermost of said rotors,

and a second inlet to said contacting zone positioned intermediate said first inlet and said rst turbulence control means.

3. An operable system including a rotating disc contractor comprising in combination:

a ltubular shell,

a plurality of annular stationary baies xed within said shell extending from the shell wall to a center opening and dividing said shell into a series of compartments,

a 4rotor shaft extending axially with respect to said shell through said opening,

a plurality of disc-like rotor baflles xed to said shaft, each rotor baille being wholly within one of said compartments and displaced a substantial distance axially from the stationary bafes thereof and extending outwardly toward the wall of said shell (each of said rotor baffles being smaller than the openings in 4the stationary ba'le toward one end of the shell from the respective rotor bafe whereby said shaft and rot-or baffle can be ymoved through said openings toward the said end of the shell),

means for rotating said rotor shaft and rotor baffles,

a first permeable turbulence control means disposed at an intermediate position within said shell below the lowermost of said rotors,

means below said first turbulence control means for withdrawal of selected uid phase from said shell,

means for cooling withdrawn selected uid phase,

means for reintroducing cooled selected fluid phase into said shell below said means for withdrawal of a selected fluid phase,

a second permeable turbulence control means disposed within said shell below said means for reintroducing cooled selected uid phase, said rst turbulence control means and said second turbulence control means delimiting a separating zone in the lower portion of said shell,

a first outlet from said shell positioned above the uppermost of said rotors,

a second outlet from said shell positioned below said second turbulence control means,

a rst inlet to said shell positioned below said rst outlet and above the uppermost of said rotors,

and a second inlet lto said shell positioned intermediate said rst inlet and said first turbulence control means.

4. An operable system including a rotating disc contactor for countercurrently contacting at least partially immiscible liquids comprising in combination:

an at least partially upright column,

a plurality of annular stationary bales xed within said column extending from the column wall to a central opening and dividing said column into a series of compartments,

a rotor shaft extending axially with respect to said column through said openings,

a plurality of disc-like rotor baiiles lixed to said shaft and extending outwardly toward the wall of said column, each of said rotor baffles being located ap- 7 proximately in the center of a compartment between the stationary baies thereof, said rotor bafes having diameters less than the diameters of the openings in the stationary bales of the respective compartments,

means for rotating said shaft and rotor baies,

a rst permeable turbulence control means disposed at an intermediate position Within said column below the lowermost of said rotors,

means below said first turbulence control means for withdrawal of a selected iluid phase from said column, means for `cooling Withdrawn selected fluid phase,

means for reintroducing cooled selected fluid phase into said column below said means for withdrawal of a selected fluid phase,

a second permeable turbulence control means disposed within said column below said means for reintroducing cooled selected tiuid phase, said rst turbulence control means and said second turbulence control means delimiting a separating zone in the lower portion of said column,

a rst outlet from said column positioned above the uppermost of said rotors,

a second outlet from said column positioned below said second turbulence control means,

a first inletto said column positioned below said first outlet and above the uppermost of said rotors,

and a second inlet to said column positioned intermediate said rst inlet and said first turbulence Control means.

References Cited in the fileof this patent UNITED STATES PATENTS 1,208,534 Foret Dec. 12, 1916 2,729,549 Reman Ian. 3, 1956 2,811,423 Bradley Oct, 29, 1957 2,881,920 Simkin Apr. 14, 1959 2,393,846 Wistrich July 7, 1959

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