US2998307A - Countercurrent multiple batch continuous extractor - Google Patents

Description

Aug. 29, 1961 A. M. WALKER 2,998,307

v CQUNTERCURRENT MULTIPLE BATCH CONTINUOUS EXTRACTOR Filed March 25, 1958 6 Sheets-Sheet 1 i .504 vavr r0 PECOVAF/P) 1 NV EN TOR. flaw/v05? MARP/orrl l/z/(M ,4 TIDE/YE) Aug. 29, 1961 A. M. WALKER 7 COUNTERCURRENT MULTIPLE BATCH CONTINUOUS EXTRACTOR Filed'March 25, 1958 6 Sheets-Sheet 2 5 0!. VENT l/VLET I NV EN TOR. m/arrfifazm/e l A 77'0/PMEY Aug. 29, 1961 A. M. WALKER COUNTERCURRENT MULTIPLE BATCH CONTINUOUS EXTRACTOR Filed March- 25. 1958 6 Sheets-Sheet 3 INVENTOR.

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A TI'OP/VG Y 2,998,307 COUNTERCURRENT MULTIPLE BATCH CONTINUOUS EXTRACTOR Alexander Marriott Walker, 699 Shepardbush Road, Birmingham, Mich., assiguor of one-half to John G. Hoad,

Ann Arbor, Mich.

Filed Mar. 25, 1958, Ser. No. 723,700 4 Claims. (Cl. 23-270) This invention relates to improvements in extractors, and in particular to extractors of the type wherein solvents are employed to extract solutes from conveyable solid material,

The primary object of this invention is to provide an improved extractor wherein a plurality of batches of material are continuously conveyed throng the extractor in one direction while a solvent moves countercurrently in batches through the extractor in the opposite direction in a manner to establish intermittent residence of the solvent in the material being treated in a plurality of extraction stages with collection and transfer of the solvent from one extraction stage to another, fresh solvent being employed at the final extraction stage at the material discharge end of the extractor and solvent of the highest degree of solute saturation being employed at the initial extraction stage at the material receiving end of the extractor, with solvent having progressively lesser degrees of solute saturation being employed at extraction stages between the said final and initial extraction stages.

Other objects of the invention will become apparent by reference to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a more or less diagrammatic isometric view of a countercurrent multiple batch continuous extractor embodying the invention.

FIG. 2 is a front elevational view of the material receiving end of the extractor.

FIG. 3 is a vertical sectional view taken substantially at the material outlet end of the extractor through the material discharge-chute thereof.

FIGS. 4, 5, 6, 7 and 8 are sectional views at a single typical flight of the extractor showing the attitude assumed successively by the material being treated and the solvent levels at the extracting, draining, drained, filling, and full positions of one extraction stage of operation of theextractor.

FIG. 9 is a key showing the shading employed throughout the drawings to indicate Solids or material being treated, Liquids or solvent, and Solids and Liquids or a combination of material being treated and solvent.

FIGS. 10 and 11 are more or les diagrammatic longitudinal sectional and front elevational views respectively showing the extractor and the material and solvent attitudes therein when the inlet and discharge chutes are vertically aligned on a -180 degree vertical axis.

FIGS. 12 and 13, 14 and 15, 16 and 17, 18 and 19 and 20 and 21 are views similar respectively to FIGS. and 11 except that the position of the extractor in each succeeding pair of views has been rotated 45 degrees clochwise as viewed from the front of the extractor in respect to its position shown in the preceding pair of views, each pair of views showing the material and solvent attitudes after the said extractor has been rotated to the particular position indicated therein.

FIG. 22 is a developed diagrammatic view of the extractor showing its multiplicity of flights and the group ing of the several flights comprising extracting Stages I, II, III and IV and the final Draining Stage, the said diagram indicating a manner in which the improved method steps may be carried out.

While the invention is illustrated in the drawings in connection with and in the form of a four stage countercurrent multiple batch continuous extractor, it should be ted States Patent 0 ice understood that different numbers of extracting stages having more or less flights per stage may be employed, and that many variations in the solvent transfer system may be adopted, all within the intent and scope of the invention herein illustrated and described.

\Although the invention is described herein as an extractor, it is obvious that the improved extractor mechanism may be modified and adapted to various chemical treating processes where countercurrent multiple batch continuous treatment is desirable or advantageous, and it is not the intent to limit the method and means of the invention to extraction only, isasmuch as the improved means is applicable to the treatment of various conveyable materials by one or more different chemicals.

'Referring now to the drawings wherein like reference characters refer to like and corresponding parts throughout the several views, the particular embodiment of a multiple stage countercurrent continuous batch extractor 20 disclosed herein for illustrative purposes consists of a drum 21 having a plurality of longitudinally spaced circumferential tracks 22 therearound by means of which the said drum 21 is rotatably supported on several pairs of trunnions 23 preferably mounted on pads 24 at the top of suitable foundation walls 25 of different height to slope the said drum longitudinally so that its front or material receiving end 26 is lower than its rear or material discharge end 27. One of the lower trunnions 23 may be power driven by such means as a motor 28 and a belt and pulley or chain drive 22 arranged as indicated in FIGS. 1 and 2 to rotate the said drum 21 on its trunnions clockwise "as viewed from the said front or lower material receiving end thereof.

The said drum 21 is provided with a continuous spiral ribbon type conveyor element 30 therein Welded or otherwise fixed to the inside surface of the said drum 21 arranged in the illustrative embodiment of the invention to provide ten continuous conveyor flights, each flight being a spirally disposed 360 degree trough-like chamber consisting of a spiral portion of the drum 21 as its base and axially spaced portions of the spiral ribbon conveyor element 30 as its sides. The flights are numbered Flights l-lO inclusive in FIG. 22 for identification. The drum 21 including the spiral ribbon conveyor element 30 welded to the inner periphery thereof form, in effect, an Archimedean screw-type conveyor which transports batches of material to be treated therein in batches from its front lower material receiving or intake end 26 to its rear upper material discharge end 27 It is well recognized in Archimedean conveyors of the above described type that material being conveyed therein assumes an angle of repose as the conveyor drum 21 rotates as illustrated by the diagonal lines in FIGS. 48 inclusive, the precise angle of repose varying according to the granular structure and coarseness of the material. Therefore, as the drum 21 rotates, the material S and/or the material S and solvent L rolls over on itself and mixes thereby intimately applying the solvent to the material to provide a more thorough solvent action than would be possible in other types of conveyors Where a thorough mechanical mixing does not take place.

The slope of the drum 21 and the amount of solvent employed in each solvent batch are such that the solvent will not spill over the low point of the low side of any flight into the adjacent lower flight.

The drum '21 has a material or solids inlet chute 31 at the front or material receiving end 26 thereof, and is provided with a material or solids outlet chute 32 at the rear or material discharge end 27 thereof. The said inlet chute 31 and the said outlet chute 32 are oppositely radially disposed as shown throughout the drawings. The inlet chute 31 and the outlet chute 32 are shown in 'a 0-18() degree attitude in FIGS. 10 11 which shows the drum 21 rotated to an angular position where a material batch charging hopper 310 is dumping a batch of material or conveyable solids into the lower or material receiving end 26 of the drum 21 through the inlet chute 3 1 which is in a vertically upwardly disposed attitude. At the same time another batch of material or conveyable solids is being dumped from the upper or material discharge end 27 of the drum 21 through the outlet chute 32 which is in a vertically downwardly disposed attitude.

The multiple stage ccuntercurrent continuous batch extractor 20 functions from its material intake end 26 to its finished material outlet end 27 in four continuous but independent extraction stages, namely, Stage I, Stage II, Stage III and Stage IV, and a Material Draining Stage. At each operating stage progressing from Stage I to Stage IV, solvent having a proportionately decreasing content of solute saturation is employed in the batch extraction operation, fresh solvent being intermittently fed in batches into Stage IV and passed intermittently in batches to succeeding Stages III, II and I as the material under extraction treatment is transferred progressively in batches from Stage I to each of Stages II, III and IV. In other words, the extractor 20 uses a different batch of solvent in each of the succeeding extraction Stages I-IV inclusive during any one cycle of operation of the extractor. A cycle of operation of the extractor may be stated as the number of revolutions of the drum 21 required to move a batch of material entering Stage I to Stage II. Since a new cycle of operation starts with each batch of material entering Stage I of the extractor 20, it is obvious that a batch of solvent suflicient to fill Stage IV must be supplied thereto each time a batch of material or solids is dumped into Stage I. The particular mechanisms for conveying and discharging batches of solvent and material or conveyable solids into the extractor 20 at proper timed relationship to the rotation of the drum 21 thereof being subject to selection by those skilled in the art of material handling, and since such mechanisms are not a part of the instant invention, they need not be described in detail herein.

At the end of the extent of each of the Stages I, II, III and IV are solvent Drains IV, III, II and I respectively. At or near the beginning of each of the Stages I, II, III and IV are solvent Fills IV, III, II and I respectively. After Drain I is a Material Draining Stage in which solvent or other chemical with which each batch of material has been treated is permitted to drain therefrom prior to the discharge of said material from the material outlet 32 of the extractor 20.

Referring particularly to FIG. 22 and as viewed therein, Stage I consists of Flights 1 and 2 and a small portion of Flight 3 up to Drain IV. Stage II consists of the greater portion of Flight 3 beginning at Drain IV, all of Flight 4 and approximately one-quarter of Flight 5 up to Drain III. Stage III consists of approximately threequarters of Flight 5 beginning at Drain III, all of Flight -6 and approximately one-third of Flight 7 up to Drain II. Stage IV consists of approximately two-thirds of Flight 7 beginning at Drain IV,- all of Flight 8 and approximately one-half of Flight 9 up to Drain I. The Material Draining Stage consists of approximately one-half of Flight 9 and Flight 10, the said flights of the Material Draining Stage having a reticulated false bottom 33 to permit solvent to drain from the material being treated before it arrives at the finished material outlet chute 32. The solvent collected in the Material Draining Stage drains therefrom into Drain I which extends thereunder.

Bearing in mind that, during each cycle of operation of the extractor 2d, a batch of material to be treated therein is fed into the extractor 20 through the material inlet chute 31 of the drum 21 thereof, a batch of fresh solvent is supplied to the drum 21 through the solvent supply line A, a batch of completely treated material is discharged from the material outlet chute 32 of the drum 21, and a batch of substantially exhausted solvent is discharged from the spent solvent outlet E of the drum 21, the several batch type operations which take place 4 in the extractor 20 illustrating the invention will now be described.

Fill I is supplied with the correct amount of fresh solvent through the fresh solvent supply line A to fill Flight 7 to the extent shown in FIG. 8 at the beginning of Stage IV each time a batch of material is discharged into Stage I through the material inlet chute 31. This fresh solvent dissolves any remaining solute from a batch of material that has just entered Stage IV during its residence therein, the said batch of material having been drained of the solvent employed in Stage III at Drain II. The partly saturated solvent of Stage IV drains at the end of Stage IV into Drain I and is transferred through the solvent transfer line B to Fill II at the beginning of Stage III.

The partially saturated solvent from Stage IV that has been supplied to the beginning of Stage III then acts upon a batch of material that has just enerted Stage III during its residence therein, the said batch of material previously having been drained of the solvent employed in Stage II at Drain III. The further saturated solvent of Stage III drains at the end of Stage III into Drain II and is transferred through the solvent transfer line C to Fill III at the beginning of Stage II.

In a like manner the said further saturated solvent that has been supplied from Stage III to the beginning of Stage II then acts upon a batch of material that has just entered Stage II during its residence therein, the said batch of material previously having been drained of the solvent employed in Stage III at Drain IV. The still further saturated solvent of Stage II drains at the end of Stage II into Drain III and is transferred through the solvent transfer line D to Fill IV at the beginning of Stage I.

The said still further saturated solvent that has been supplied from Stage II to the beginning of Stage I then acts upon a batch of material that has just entered Stage I through the material inlet chute 31 at the front or material receiving end of the drum 21 during its residence in the said Stage I. At the end of Stage I, the solvent is substantially saturated and drains into Drain IV from whence it is discharged from the drum 21 of the extractor 20 through the spent solvent outlet E into spent solvent catch basin 34. The spent solvent is preferably piped from the spent solvent catch basin 34 to a solvent recovery unit (not shown), or is disposed of otherwise.

In FIGS. 4, 5, 6, 7 and 8, the disposition of the solids S, liquids L, and combined solids and liquids S and L are indicated at various typical flights wherein a portion of a cycle of operation of the extractor designated as Extracting, Draining, Drained, Filling and Full respectively occurs, the said solids S, liquids L, and solids and liquids S and L being illustrated by employing the key shown in FIG. 9. In FIGS. 10, 12, 14, l6, l8 and 20 is illustrated the functioning at the several flights and stages of operation of the extractor and the disposition of solids and combined solids and liquids therein when the said extractor is rotated to the angular positions shown in FIGS. 11, 13, 15, 17, 19 and 21 respectively. Throughout the drawings, where convenient, the inlet line is designated A, the fluid transfers are designated B, C and D, Drains I, II, III and IV are designated D-I, D-II, D-III and D-IV, and Fills, I, II, III and IV are designated F-I, F-II, F-III and F-IV.

It will be noted that although the illustrative embodiment of the invention consists of four extracting stages with approximately two flights per stage, countercurrent multiple stage continuous extractors embodying the invention may be arranged to use any number of stages with any number of flights per stage, all according to the requirements of the particular extraction operation to be performed by the extractor. 'Furthermore,'the arrangement of solvent drains and fills may be altered to accommodate countercurrent multiple batch extractors embodying the invention to particular extraction or chemical treatment requirements and/ or processes.

Although but a single embodiment of the invention has been disclosed and described in detail herein, it is obvious that many changes may be made in the size, shape, artrangement and details of the several elements of the invention, and that the method steps may be varied, all without departing from the spirit and scope thereof as defined by the appended claims.

I claim:

1. In a countercurrent multiple batch continuous extractor comprising an Archimedean type drum conveyor including a drum disposed on an incline and a continuous spiral ribbon type conveyor element fixed in sealed re lationship to said drum forming a plurality of 360 degree flights therein, means rotating said drum conveyor whereby to convey batches of material therethrough while continuously mixing the same, material inlet and outlet means at the lower upper ends of said drum conveyor respectively through which batches of material enter and leave said drum, a fresh solvent inlet means including a first solvent fill located to discharge into a selected flight near the upper end of said drum conveyor, a first solvent and solute drain located at the uppermost flight of said drum conveyor communicating with and including a second solvent and solute fill located at a selected flight below said first solvent fill through which solvent and solute are transferred by gravity from said first solvent and solute drain to said second solvent and solute fill, a second solvent and solute drain located at the said second selected flight rotatably ahead of said first solvent fill communicating with and including a third solvent and solute fill located at a selected flight below said second solvent and solute fill, and repeating said communicating solvent and solute drain and fill elements in like arrangement until the last solvent and solute fill is located in the lowermost conveyor flight and the last solvent and solute drain is located in a selected flight rotatably ahead of the last previous solvent and solute fill, the last solvent and solute drain being adapted to discharge spent solvent from the extractor, each said communicating solvent and solute drain and fill elements extending axially between spaced conveyor flights independently of said spiral ribbon type conveyor element.

2. A countercurrent multiple batch continuous extractor comprising an Archimedean type drum conveyor including a drum disposed on an incline and a continuous spiral ribbon type conveyor element fixed in sealed relationship to said drum forming a plurality of 360 degree flights therein, means rotating said drum conveyor whereby to convey batches of material therethrough simultaneously turning said material over on itself, a material inlet at the lower end of said drum conveyor through which a batch of material may be introduced into the first flight at selected revolutions thereof, a material outlet at the upper end of said drum conveyor through which a batch of material conveyed therethrough may be discharged from the last flight at selected revolutions thereof, a fresh solvent inlet means including a fill at the end thereof extending into the upper end of said drum conveyor with the fill located to discharge a batch of fresh solvent at a first selected intermediate flight near the upper end of said drum, a first drain means located at the uppermost flight of said drum conveyor communicating with and including a second fill located at the lower end thereof conveying said solvent by gravity to a second selected intermediate flight spaced below said first selected intermediate flight, a second drain means located at the said first selected intermediate flight rotatably ahead of said fresh solvent fill communicating with and including a third fill at the lower end thereof conveying said solvent by gravity to a third selected intermediate flight below said second selected intermediate flight, and repeating said communicating drain and fill elements in like arrangement until the last fill is located in the lowermost of the conveyor flights and the last drain is located in a selected intermediate flight rotatably ahead of the last previous 6 fill, each said communicating drain and fill element extending between spaced conveyor flights independently of said spiral ribbon type conveyor element.

3. In a countercurrent multiple batch continuous extractor comprising a rotatable Archimedean type drum conveyor disposed on an incline including therein a continuous spiral ribbon fixed in sealed relationship to said drum forming a plurality of 360 degree flights therein adapted to move material through said conveyor while turning it over on itself, material inlet and outlet means at the lower and upper ends of said drum conveyor respectively through which batches of conveyable material enter and leave the drum, means delivering fresh solvent into a first selected flight near the upper end of said conveyor, a drain for draining said solvent at a flight above said first selected flight including gravity transfer means discharging said solvent into a second selected flight below said first selected flight, a drain for draining said solvent at a flight above said second selected flight including gravity transfer means discharging said solvent into a third selected flight, and repeating said drain and gravity transfer means until the last transfer means discharges solvent into the lowermost of the conveyor flights, and a drain for draining solvent from said conveyor located at a selected conveyor flight above the said lowermost conveyor flight, in each instance the said solvent being elevated by said conveyor with a batch of material from each flight into which said solvent is discharged to a higher flight having a drain therein, each said drain and gravity transfer means extending between spaced conveyor flights and disposed external of the conveyor drum in longitudinal overlapping relationship with respect to each other.

4. A countercurrent multiple batch continuous extractor consisting of an inclined Archimedean type drum type spiral conveyor including a drum and a plurality of 360 degree continuous flights therein fixed in sealed relationship to said drum whereby to convey material through said conveyor while turning the material over on itself, a material inlet chute at the low end of the said drum and a material outlet chute at the high end there of, means rotating said drum causing batches of material fed into said inlet chute to be conveyed therethrough and discharged through said outlet chute, a fresh solvent inlet discharging solvent into a selected flight near the upper end of said conveyor drum, a solvent and solute outlet drain at a selected flight near the lower end of the said conveyor drum, a plurality of gravity solvent transfer means consisting of a solvent drain, a solvent transfer line and a solvent inlet located at selected flights transferring solvent sequentially from a higher flight to a lower flight for residence in material in each said lower flight as it is conveyed to each said higher flight, said gravity transfer means being located to apply solvent in batches having progressively increased solutes therein at spaced flight intervals from the upper flights to lower flights of the said drum conveyor whereby to provide a residence of each solvent batch in material batches in the several flights between each solvent inlet and the solvent drain next thereabove, said gravity solvent transfer means extending between spaced conveyor flights of said conveyor drum and located externally of said conveyor drum in longitudinal overlapping relationship in respect to each other.

References Cited in the file of this patent UNITED STATES PATENTS 1,860,388 Hornbrood May 31, 1932 2,012,298 Berge Aug. 27, 1935 2,273,557 Bonotto Feb. 17, 1942 2,337,137 Thompson et al. Dec. 21, 1943 2,390,388 'Rector Dec. 4, 1945 FOREIGN PATENTS 417,302 Great Britain Oct. 2, 1934

Claims (1)

1. IN A COUNTERCURRENT MULTIPLE BATCH CONTINUOUS EXTRACTOR COMPRISING AN ARCHIMEDEAN TYPE DRUM CONVEYOR INCLUDING A DRUM DISPOSED ON AN INCLINE AND A CONTINUOUS SPIRAL RIBBON TYPE CONVEYOR ELEMENT FIXED IN SEALED RELATIONSHIP TO SAID DRUM FORMING A PLURALITY OF 360 DEGREE FLIGHTS THEREIN, MEANS ROTATING SAID DRUM CONVEYOR WHEREBY TO CONVEY BATCHES OF MATERIAL THERETHROUGH WHILE CONTINUOUSLY MIXING THE SAME, MATERIAL INLET AND OUTLET MEANS AT THE LOWER UPPER ENDS OF SAID DRUM CONVEYOR RESPECTIVELY THROUGH WHICH BATCHES OF MATERIAL ENTER AND LEAVE SAID DRUM, A FRESH SOLVENT INLET MEANS INCLUDING A FIRST SOLVENT FILL LOCATED TO DISCHARGE INTO A SELECTED FLIGHT NEAR THE UPPER END OF SAID DRUM CONVEYOR, A FIRST SOLVENT AND SOLUTE DRAIN LOCATED AT THE UPPERMOST FLIGHT OF SAID DRUM CONVEYOR COMMUNICATING WITH AND INCLUDING A SECOND SOLVENT AND SOLUTE FILL LOCATED AT A SELECTED FLIGHT BELOW SAID FIRST SOLVENT FILL THROUGH WHICH SOLVENT AND SOLUTE ARE TRANSFERRED BY GRAVITY FROM SAID FIRST SOLVENT AND SOLUTE DRAIN TO SAID SECOND SOLVENT AND SOLUTE FILL, A SECOND SOLVENT AND SOLUTE DRAIN LOCATED AT THE SAID SECOND SELECTED FLIGHT ROTATABLY AHEAD OF SAID FIRST SOLVENT FILL COMMUNICATING WITH AND INCLUDING A THIRD SOLVENT AND

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