US2029691A - Countercurrent contactor - Google Patents

Description

Feb. 4, 1936. Y

J. ROBINSON COUNTER CURRENT CONTACTOR Filed Aug. 12, 1953 4 HNVENTOR' Jack, Robmaon BY M-Bwmw,

ATI'QRNEY @tente re. a we weasel communes-near oonraeron Jack ltphilnsoh, Wood River, 111111., assignor ta Standard Uil illompany, (Chicago, lllilt.9 a cor poration of llindiana Application August 12, was, serial its. teases e creams. (oi. ite -it) This invention relates to apparatus for the countercurrent contacting of two fluids, particularly two liquids. It is especially adapted to the extraction of petroleum fractions, for instance alubricating oil stockfwith a selective solvent or solvent mixture.

It is an object of my invention to provide an apparatus of the above type which will accomplish eiiieient equilibrium contacting of the two fluids in each of a plurality of stages. Another object is to provide an apparatus in which this can be accomplished together with the attainment of maximum throughput. Other and more detailed objects will become apparent as the description of my invention proceeds.

My invention will now be described in detail with reference to the preferred embodiment shown in the accompanying drawing in which Figure 1 is an elevation of my countercurrent contactor partly in section; and

Figure 2 is a partial elevation taken along the line 2--2 of Figure 1.

Referring now to the drawing in more detail, a generally horizontal casing l I, which may suitably be of the approximate cross-section shown in' Figure 2, rests on supports I2 and is divided into two end compartments I3 and a plurality of intermediate compartments l4 by means of is also provided with a fluid inlet 22 equipped with a valve 23 and the left hand end compartment I3 is equipped with a fluid inlet 24 which is provided in turn with a valve 25. Inlet 22 is preferably, but not necessarily, located near the top of right hand end compartment I 3 andinlet 24 is preferably, but not necessarily, located near the bottom of left hand end compartment l3.

Intermediate compartments l4 are provided with downwardly projecting bailies 26 which may suitably be segmental in form and are preferably approximately perpendicularly disposed with respectto the axis of casing ll. Baflies 26 may be centrally'locatedin compartments l4 but are preferably located somewhat nearer to the right hand end of the compartment As will be explained later this may be referred to as the up stream end of the compartment. Compartments it arelikewise provided with upwardly project= ing baflies 2'! which may suitably be segmental in shape and are'preferably approximately per-=- i'pendicularly disposed with respect to the axis of casing ll. Baflies 2'1! are preferably located somewhat closer to the left or upstream end oi the compartment than to the other end.

Casing M or a portion of it is traversed by shafts 23 and 29 which are preferably located in vertical alignment with each" other and parallel to the axis of easing ii. Shaft 22, in the form shown in Figure l, is journaled at 30, $0,

and 32 and is driven from drive shaft tit by means of a pair of variable pulleys 3t and a belt 35. Similarly, shaft 29 is journaled at 36, ill and 38 and is driven through drive shaft 32 by means of a pair of variable pulleys 39 and the belt til. Drive shaft 33 is in turn driven through pulleys 4i, belt 42 and variable speed reducer 43 by means of motor 4t. Variable speed reducer 43 is controlled by means of lever 25. It is thus possible to drive shafts 28 and 29 at a wide range of selected rates of rotation. Furthermore, by means of pulleys 34 and/or pulleys 39 the rates of rotation of the two shafts can be independently varied. It is also possible to change the direction and location of either of the shafts by closing belt 35 or belt 40.

Bafliles 26 divide the upper portions or intermediate compartments i4 into upper upstream zones 46 and'upper downstream zones 41. Shaft 28 carries paddle wheels at which are located within or project into upper upstreamzones 46. Similarly, baflies 21 divide the lower portions of intermediate compartments l4'into lower upstream zones 49 and lower downstream zones 50. Paddle wheels 5| are carried by shaft 29 within or projecting into lower upstream zones 49. The paths 52 of the tips of paddle wheels 48, as shown in Figure 2, project upwardly to points above the lower edges of baflles 26 but below the upper edges of baflles l5. Similarly the paths 53-of the tips of paddle wheels 5| project at their lowest points 4 below the upper edges of baiiles 21 but above the lower edges of baffles I 5. The reason for this will become apparent later in the description. Shafts 28 and 29 should be so located that paddle wheels 48 and 5| will fulfill the foregoing re- 5 These gas vents are connected to manifold 55 by means of valves 56. Manifold 55 is also provided with a master valve 51.

Having described my countercurrent contacting apparatus I will now proceed to outline the processes for which it is adapted and its functional advantages with respect to those processes. The apparatus can be utilized for the contacting of any twofluids, but it is particularly adapted to contacting two liquids which are not completely miscible with each other under the prevailing operating conditions and which are substantially different in specific gravity.

The liquid of lower specific gravity is intro duced through inlet 22 by means of valve 23 and flows through casing ll past and around the various baiiies l5 and 26 and finally past battle 58 up into extension 19 and out through outlet 20 and valve 2|. Simultaneously the liquid of higher specific gravity is introduced through inlet 24 by means of valve 25 and fiows along the bottom of easing Ii past the various bafiies i5 and 21, finally past baffle 59, into downward extension [6 and then out of the apparatus through outlet [1 and valve l8. While the two liquids are thus being fiowed through the apparatus in countercurrent contact with each other, shafts 28 and 29 are rotated by means of motor M, etc. at optimum speeds to be determined as hereinafter described. Paddle wheels 48 and 5! attached to shafts 28 and 29 respectively are rotated thereby. The rotation of these blades tends to promote emulsification between the two liquids being contacted. This is highly desirable since it insures intimate contact and the attainment of equilibrium between the two liquids. Nevertheless, it is desirable that the emulsion after being formed be broken so that the unemulsified liquid can pass on to the next stage of the process and again to undergo emulsification.

My invention makes this desirable result possible and in effect makes each of compartments ll a distinct stage wherein equilibrium is obtained and the two liquids pass on in opposite directions to the next stages.

The method by which this is accomplished will be described with particular reference to the right hand one of compartments H which may be taken as typical. The lighter liquid entering the apparatus through inlet 22 passes over the top of the right hand one of baffies I5 and enters upper upstream zone 46 wherein it is vigorously agitated by paddle wheel 48. This agitation together with the agitation provided by paddle wheel 5| located in the lower left hand portion of compartment 14 produces a central zone of emulsified material wherein the two liquids are in intimate contact within each other. A portion of this emulsified material passes around the lower end of baffle 26 and into the upper downstream zone 41 wherein there is no agitation and the light liquid which has been in contact with the heavy liquid settles out and passes over the top of the next bafiie 15 into the next compartment. Simultaneously heavy liquid enters compartment H at the lower left and comes into lower upstream zone 49 wherein it is vigorously agitated by means of paddle wheel 5|. A por tion of the emulsified material passes over the top of bafiie 21 and the lower liquid settles out in the lower downstream zone 50 and then passes out of the compartment at the lower right. Both the light and heavy liquids thus first enter a vigorous agitation zone and are contacted with the other liquid and then enter a relatively quiescent zone in which they settle out and pass on in the next compartment. The quiescent zones should preferably be rather larger than the agitation zones.

The approximate preferred interfacial levels between each of the liquids and the emulsification zone are shown by dashed lines in Figure 1. It will be understood, of course, that these lines are approximate only since in many cases the emulsified layer will gradually taper off into the unemulsified layer. In the right hand end compartment I3 interfacial level should be relatively high in order to permit the settling out of entrained light liquid from the heavy liquid being withdrawn through outlet 11. Similarly interfacial level 60a in left hand end compartment l3 should be relatively low so as to permit the settling out of entrained heavy liquid from the light liquid being withdrawn through outlet 20. Level 50a must in general be above level 66 so that the hydrostatic head necessary to secure flow through the apparatus can be secured. Interfacial level 8! in upper upstream zone 16 represents the approximate interface between the light liquid and the emulsified material. level should preferably meet bafliel5 near the top thereof. After flowing around baiile 25 into relatively quiescent zone 47, the level '52 between. the light liquid and the emulsified material will be somewhat lower than level 6i due to the absence of agitation. Similar considerations apply to levels 63 and 64 representing the approximate interfaces between the heavier liquid and the emulsified material.

These optimum results can be obtained by com trol of the rates of rotation of shafts 28 and 29, by control of valves l8, 2!, 23, and 25 and if desired by the use of interracial liquid level controls (not shown) located in one or both of end compartments i3 cooperating with one or more of valves l8, 2 l, 23, and 25. In the preferred method an interracial liquid level control is used in one of end compartments I3 in cooperation with a pressure control valve located in the outlet from the opposite end compartment.

The provision of gas vents 54 is of great importance when contacting two liquids, since the accumulation of air, vapors, etc. in the upper portions of the various compartments, particularly immediately on the upstream sides of baiiies 28 may otherwise interfere seriously with the operation of the apparatus.

While paddle wheels 48 and 5| may suitably be formed of fiat blades, cups, etc. facing in the direction of rotation, it is sometimes desirable to slope them slightly so as to help propel the two liquids in their respective downstream directions. This tends to increase the throughput of the device. Too great a propulsion must be avoided however, since it interferes with the attainment of equilibrium in each stage. It is also sometimes desirable to use more than two paddles in each of compartments ll. The paddles should, however, be confined largely to zones 46 and 49.

It is a matter of considerable importance that the angle at which casing l l is tilted to the horizontal be carefully selected. If this angle is too small the rate of flow through my apparatus will be very' small and the aforementioned relationships between the various interfacial levels cannot be obtained. On the other hand, there is an upper limit, angles larger than which cannot be used without sacrifice of efliciency or operability. Angles from about 5 to about 30 can be used although angles from about 8 to about 20 are This aoaaooi preferable. The term "generally horizontal ap plied herein to casing l l covers angles from 0 to or to the horizontal.

While my process and apparatus can be used for contacting any two fluids and particularly for the contacting of any two non-miscible liquids differing substantially in specific gravity, it is peculiarly adapted to countercurrent extraction of petroleum fractions and more particularly to countercurrent extraction of lubricating oil stocks. In a preferred embodiment the material introduced through inlet 22 and withdrawn through outlet 2t] is a lubricating oil stock, and the material introduced through inlet 2d and withdrawn through outlet W is a selective solvent such as dichlorethyl ether, nitrobenzene, cresylic acid, phenol, sulfur dioxide or a mixture of sulfur dioxide and benzol.

. the unemulsifled material tends to rotate with the til) paddles with the result that it is carried under or over one end of the edges of battles it: or til with consequent short-circuiting. In other words, a portion of the material passes from agitation zone it to quiescent zone dli or from agitation zone iii to quiescent zone till without having been emulsified. Ihis can be remedied by dis= placing battles 2t and/or 2i! in the direction of the rotation of the corresponding paddle wheels so that thisVshort-circuiting will not occur. Alter-=- natively the bafiies can be extended on the edge over or under which the unernulsified liquid passes so that short-circuiting will be prevented.

While I have described my invention in corn nection with a specific embodiment thereof, 1 do not wish to be limited thereby but only to the scope of the appended claims in which if have set forth the novel features of my invention.

I claim:

1. Apparatus for the countercurrent contacting of two comprising a generally horizontal casing, a plurality of bailies partially dividing said casing into a plurality of compartments, and in dependent agitation means located in and corniined to diagonally disposed portions of said compartments.

2. Apparatus for the countercurrent contacting of two fluids, comprising a generally horizontal casing, a plurality of baflles partially dividing said casing into a plurality of compartments, baffles dividing the upper portions of said compartments into two upper zones, bafiles dividing the lower portions of said compartments into two lower zones, agitation means located in and confined to one of said upper zones and agitation means located in and confined to one of said lower zones diagonally disposecl'with respect to said last mentioned upper zone.

3. Apparatus for the countercurrent contacting of two fluids, comprising a generally horizontal casing, a plurality of bailles disposed approximately perpendicularly to the axis of said casing and dividing said casing into'two end compartmentsand a plurality of intermediate compartments, a plurality of bafiies extending from the top g f said easing into said intermediate compartments and dividing said intermediate compart-' ment into two upper zones, a plurality of baflles extending from ,the bottom of said casing into said intermediate compartments and dividing said intermediate compartmentsinto twp lower zones, a shaft traversing said upper zones, a second shaft traversing said lower zones, means for roe tating said shafts, agitation means carried by said first-mentioned shaft within at least one of said upper zones, agitation means carried by said second shaft within at least one of said lower zones diagonally disposed with respect to said last-mentioned upper zone, a fluid inlet located in each of said end compartments and a fluid outlet located in each of said end compartments.

l. Apparatus for countercurrent contacting comprising a generally horizontal casing, a plurality of bafiles disposed approximately perpendicularly to the axis of said casing and dividing said easing into two end compartments and a plurality of intermediate compartments, a plurality of battles extending from the top of said casing into each of said intermediate compartments and dividing each of said intermediate compartments into a downstream upper zone and an upstream upper zone, a plurality of baffles extending from the bottom of said easing into each of said inter mediate compartments and dividing each of said intermediate compartments into a downstream traversing said upper zones, a second shaft traversing said lower zones, means for rotating said shafts, means for controlling the rates of rotation of said shafts, agitation means carried by said first-mentioned shaft Within said upstream upper zones, agitation means carried by said second shaft within said upstream lower zones, a fluid inlet located in each of said end compartments and a fluid outlet located in each of said end compartments.

5. Apparatus for countcrcurrent contacting comprising a generally horizontal casing, a plu rality of baffles disposed approximately perpendicularly to ,the axis of said casing and dividing said casing into two and compartments and a plurality of intermediate compartments, a plurality of baffles extending from the top of said casing into each of said intermediate compartments and dividing each of said intermediate compartments into a downstream upper zone and an upstream upper zone, a plurality of baflles extending from the bottom of said easing into each 0 of said intermediate compartments and dividing each of said intermediate compartments into a downstream lower zone and an upstreamlower zone, a shaft traversing said upper zones, a second shaft traversing said lower zones, means for rotating said shafts, means for controlling the rates of rotation of said shafts, means located substantially within said upstream upper zones and carried by said first-mentioned shaft for agitating the material in the upper portion of said casing and propelling it downstream, means lower zone and an upstream lower zone, a shaft iii) located substantially within said upstream lower' 6. Apparatus for countercurrent contacting comprising a generally horizontal casing, a plurality' of bafiles disposed approximately perpendicularly to the axis of said casing and dividing said casing into two end compartments and a plurality of intermediate compartments, upper passages located near the tops of said baflles connecting each adjacent pair of said compartments, lower passages located near the bottoms of said baffles connecting each adjacent pair of said compartments, a plurality of baflles extending from the top of said casing into each of said intermediate compartments and dividing each of said intermediate compartments into a downstream upper zone and an upstream upper zone, a plurality of baffios extending from the bottom of said casing into each of said intermediate compartments and dividing each of said intermediate compartments into a downstream lower zone and an upstream lower zone, a shaft traversing said upper zone, agitation means carried by said shaft substantially within said upstream upper zones and extending upward to a maximum height above the lower edges of said second-'mentioned baiiies and below said upper passages, a second shaft traversing said lower zones, agitation means carried by said second shaft substantially within said upstream lower zones and extending downward to a maximum depth below the upper edges of said third-mentioned bafiles and above said lower passages, means for rotating said shafts, means for controlling the rate of rotation of said first-mentioned shaft, means for controlling the rate of rotation of said second shaft, a fluid inlet located in each of said end compartments and a fluid outlet located in each of said end compartments'.

7. Apparatus for the countercurrent contacting of two liquids incompletely miscible with each other and differing substantially from each other in specific gravity, comprising a casing inclined to the horizontal, a plurality of baflles partially dividing said casing into a plurality of compartments, and independent agitation means located in and confined to diagonally disposed portions of said compartments.

8. Apparatus for the countercurrent contacting of two liquids incompletely miscible with. each other and differing substantially from each other in specific gravity, comprising a casing inclined to the horizontal, a plurality of baffles disposed approximately perpendicularly to the axis of said casing and dividing said casing into two end compartments and a plurality of intermediate compartments, a plurality of baffles extending from the top of said casing into said intermediate compartments and dividing said intermediate compartment into/two upper zones, a plurality of baflies extending from the bottom of said casing into said intermediate compartments and dividing said intermediate compartments into two lower zones, a shaft traversing said upper zones, a second shaft traversing said lower zones, means for rotating said shafts, agitation means carried by said first-mentioned shaft within at least one of said upper zones, agitation means carried by said second shaft within at least one of said lower zones diagonally disposed with respect to said last-mentioned upper zone, a liquid inlet located in each of said end compartments and a. liquid outlet located in each of said end compartments.

9. Apparatus for the countercurrent contacting of two liquids incompletely miscible with each other and differing substantially from each other in specific gravity comprising a casing inclined to the horizontal, a plurality of baffles disposed approximately perpendicularly to the axis of said casing and dividing said easing into two end compartments and a plurality of intermediate compartments, a plurality of baiiies extending from the top of said casing into each of said intermediate compartments and dividing each of said intermediate compartment s into a downstream upper zone and an upstream upper zone, a plurality of baffles extending from the bottom of said easing into each of said intermediate compartments and dividing each of said intermediate compartments into a downstream lower zone and an upstream lower zone, a shaft traversing said upper zones, a second shaft traversing said lower zones, means for rotating said shafts, means for controlling the rates of rotation of said shafts, means located substantially within said upstream upper zones and carried by said firstmentioned shaft for agitating the material in the upper portion of said casing and propelling it downstream, means located substantially within said upstream lower zones and carried by said second shaft for agitating the material in the lower portion of said casing and propelling it downstream in a direction opposed to the downstream direction of the material in the upper portion of said casing, a fluid inlet located in each of said end compartments and a fluid outlet located in each of said end compartments.

JACK ROBINSON.

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