US2206595A - Method and apparatus for continuous counter-current solvent extraction of solid materials - Google Patents

Description

y W46)- M. BONOTTO ZSZUGSQS METHOD AND APPARATUS FOR CONTINUOUS COUNTER-CURRENT RIALS SOLVENT EXTRACTION OF SOLID MATE 2 Sheets-Sheet l Filed Dec. 13, 1937 16 Dwalbary'fl Pezforalfll Storage Bin Maz or 17 16 14 INVENTOR Michele Hana/7 0 BY *1 io% ATTORNEY BONOTTO 2,20%595 M. METHOD AND APPARATUS FOR CONTINUOUS COUNTER-CURRENT SOLVENT EXTRACTION OF SOLID MATERIALS Filed Dec. 15, 1937 2 Sheets-Sheet 2 SA 22 6 LeveT INVENTOR MdzeZe 501w BY u x I ATTORNEY d/ecfar Patented July 2, 1940 UNITED STATES METHOD AND APPARATUS FOR CONTINU- OUS COUNTER-CURREN T SOLVENT EX- TRACTION OF SOLID MATERIALS Michele Bonotto, Evansville, Ind., assignor to Extractol Process, Ltd., Wilmington, Del., a corporation of Delaware Application December 13, 1937, Serial No. 179,458

7 Claims.

This invention relates to a'method and apparatus for continuous counter-current solvent extraction of solid materials and though useful generally, is particularly adapted for the extraction of fats and oils from products of such nature or qualities that the extracted material will be incapable of forming or in which difiiculty is experienced in forming, at the discharge end of an extraction unit, a liquid-impervious plug of sufficient density to hold back the solvent liquid during discharge of the exhausted material at atmospheric pressure.

One of the objects of this invention is to provide a method and means whereby extracted material of the type hereinabove specified from an extraction unit may be sufiiciently compressed under pressures equalized on both sides of the compressed zone to block passage therethrough of the solvent supply and permit a counter-flow tion system where raw material is fed at one end, exhausted material is discharged through a unit outlet at the opposite end, and solvent is passed in counter-current therethrough, to provide means for equalizing the hydrostatic pressure at opposite sides of the discharge outlet, means for compressing exhausted material adjacent to said discharge end and means for by-passing a supply of fresh solvent around the dischargeoutlet while maintaining such equalized hydrostatic pressure at opposite sides of the discharge outlet.

Still another object of my invention is, in an apparatus of the character specified, to utilize, in combination with a column of liquid solvent con nected with the discharge end of an extracting unit to equalize the hydrostatic pressure therein, a solvent by-pass from such solvent column, a supply pump of given capacity for feeding solvent to said solvent 001mm, and a by-pass pump of a capacity substantially equal to the capacity of the supply pump, whereby the equalizing pressure of said solvent column will be maintained at the discharge side of the discharge conduit and the feed of the solvent to the system and the input Another object of my invention is, in an extracof solvent to the extraction unit through the bye pass will be substantially equal in quantity.

Another object of my invention is to provide for material discharged from an extraction unit an elevating conveyor having ascending and decending legs and to utilize one of such legs as a material conveying leg for exhausted material while employing the other leg to provide a column of solvent of suitable hydrostatic pressure.

Still another object of my invention comprises the provision, in a conveyor of the character specified, of means for washing the exhausted material with fresh solvent by causing such solvent to peroolate in counter-current through such exhausted material during elevation of the same to the conveyor discharge outlet and preferably adjacent to said outlet.

Another object of my invention is, in a conveyor device of the type specified, to provide for the drainage from ascending exhausted material soaked during the aforesaid percolation of solvent and the conduction of such drained solvent to the pressure-equalizing solvent column.

With these and other objects in view, the invention comprises the combination of members and arrangement of parts so combined as to act and co-operate with each other in the performance of the functions and the accomplishment. of the results herein contemplated, and

comprises in one of its adaptations the species or preferred form illustrated in the accompanying drawings, in which:

Fig. .1 is a view partly schematic and partly in vertical sectionshowing an apparatus capable of carrying out my invention;

Fig. 2 is a cross-section on the line 2-2 of Fig. 1, looking inthe direction of the arrows;

Fig. 3 is a cross-section on the line 3-3 of Fig. 1, looking in the direction of the arrows;

4 is an enlarged fragmentary sectional view of a part of one of the revolving partition discs and the stationary arm shown in Fig. l;

Fig. 5 is an enlarged fragmentary section of the upper part of my conveyor;

Fig. 6 illustrates a modified form of conveyor apparatus capable of use in my invention;

Fig. 7 is a view partly schematic, partly in vertical section and partly in elevation showing a modified form of my apparatus;

Fig. 8 is a fragmentary sectional View of another form of my apparatus similar to Fig. 7 but slightly modified;

tion and partly in elevation showing still another modified form of my apparatus; and

Fig. 10 is a section on the line Ifllil of Fig. 8, looking in the direction of the arrows.

Referring now to Figs. 1 to of these drawings which illustrate a preferred embodiment of my invention, l indicates an extraction unit of a type similar to that disclosedin my co-pending patent application Serial No. 48,646, and com prises, as shown, a vertically arranged cylindrical tank having, at its upper end, an inlet 2 for solid operating in a feed conduit 4.

passed by gravity through a series of successive superposed extraction zones 6 separated from each other by revolving discs I eachhaving a radial opening 8 disposed out of registration with preceding and succeeding openings, and 1 each zone preferably being provided with stationary vertically-disposed radially-extending arms 9 adapted tohold the solid materialzagainst turning with the revolving discs 1,. v-The; tank .I has, at its lower end, an inlet I0 forlsolvent andthe solid material and solventare caused :to niovezin counter-current with each". other throughathe openings 8 in the revolving discs I which are' provided at their perimetric edges with inset expansion rings 3 which rub and bear againstthezinternal surface of the tank so .asto provide a sub stantially liquid-tightzdoint between zones and to compel the liquid solvent materialto. pass through the openings 8tin the revolving .discs in counter-current with the movement ofmtheraw solid material. During such; counter-current movement, the oil, fat or like soluble contents will be extracted from suchraw material, and the exhausted material willbedischargedat or adjacent to the bottom 0f the tank while ithe miscella will be discharged at or, adjacent tothe top ofthe tank. ,In the: embodiment shown, the partition members .or discs Tare rotated by an axial shaft H rotatable bybevel-tgears: LI,- 1 l the'latter of which is fixedon a'shaft; llturned byamotor-l3. l My present methodand apparatusthough capable of general use withalltypes of; material, is particularly adapted for use with raw material such as scrap meat which, in itsexhausted form, does not provide, sufiicient body or texture to per. mit or enable the formation, at thedis'charge end of the extraction unit, of a liquid-impervious 'plug which will have suflicient ,density to withstand or hold back the hydrostatic pressure-with the extraction unit while-dischargingexhausted material atatmospheric pressure. JIo overcome this difficulty,-I substantially equalize the hydrostatic pressure on QppOsitesides of the dischargeconduit of an extraction unit by providing a column Ofsolvhtbbnhecte'd with the discharge'end of such conduit andll 'tlce'n by pass, around such discharge conduit, a supply of solvent and compress' s uch exhausted material in a zone adjacent to the discharge outlet to produce a compressed mass having adensity and impenetrability to liquid which" though insufficient to'hold backliquid if" discharged atatmospheric pressure, will, however, be greater than the frictional resistancelwhich will beencountered by the -by passed solvent in' its passage through the les'se'compact' solid"material-inthe extraction unit and thus to permit ithe' amassed solvent ,tov move in counter-current withsuch tated through gears l'I, I! by a motor I8, and

turning in the conduit M. The said screw 56 has .S i-t's end projectinginto an extension conduit l4 having, at its; outer end, a spring-pressed valve Me and projecting into an enclosed delivery box M for the conveyor 15; said delivery box M having, at its lower end, an opening M which comiminicates with the conveyor l5 through a horizontal portion 15' which in turn connects through the elbow portion I5 with a vertical portion I5 which extends upwardly a sufficient distance to contain a column of solventhaving a liquid level F, similar to the liquid, level .F in thewextraction tank l,. and .to convey' exhausted or extracted material above said level, f J i i This conveyor l5.,may be of any suitable or conventional type, but, will preferablyflcomprise an: elevating conveyor-channel, or ascending leg, in whichsolid material is adapted to be elevated by suitable members l5 ,while moving upwardly anda return channel l5? or descending leg for enclosure of the elements I5 while descending or moving downwardly. In accordance-withmy invention, said descending leg l5 is utilized as a container for solvent and provides, when filled with solvent, a. solvent columnproviding an equalizing hydrostatic pressure to; counteract the hydrostatic pressure in the unit and also a supply leg for feeding solvent .to the extractor unit :at such equalized pressure. In accordance with the preferred form of--my5invention illustrated in Figs. .1 and'2, I preferably utilize a chain conveyor having aseries of: carrier, members I54 providedwith projecting'forked portions I5 and adapted to, carry the, exhausted material en masse through the elevating channel lli andto provide a partition, 16 separating the ascending anddescending channels or flights,and,-.as aforesaid, the descending channel risiutilized toxpro-l videa solvent reservoir or hydrostatic head for the dual purposes of equalizing pressure at the 50 dischargeend of the extraction unit andof pro- ,viding a supply of solvent to be byj-passed there from to the lower end of" the extraction unit. I In accordance with my said invention,'the conv'eyor extendsabovethe common liquid level in the extraction unit and-conveyor leg,to a dis charge "outlet conduct II and solvent issupplied tothe saiddescending leg or 5 channel of such conveyor above "said liquid level at is, thug forming said hydrostatic head or column" which communicates pressure through the delivery box M to the discharge side ofj'thejdischargecon duit. A 1 Y In accordance; with the preferredfor-m of my invention'f illustrated, raise treat the r-extracted material in theconveyor by'causing'thefre sh sol- Vent topercolate,therethrough atfor adjacent to the final discharge llfor suchextracted material, The solvent thus'percolated throughsuchmaterial isalso causedito drain into thes'olvent'column in the descendingconveyor leg. To'provide for such percolatingianddraining of solvent, I' provide the upper partof the conveyor aboveithe solvent level F" with"aperforated partition l'fi fcbntinlie one with the partition 16. Thus fresh solvent supplied at 18 will percolate the upwardly moving solid material from B to R, which'comprlses a zone fromsaid solvent inlet to the liquid ,lVel F and above said percolating'zone liquid will drain from said material through said perforated partition, thus forming a drainingzone from R to A which includes the area between the solvent inlet and the material outlet.

In accordance with the preferred form of my invention, I by-pass, through pipes ID" and S from the solvent column to the bottom of the extraction tank, a supply of extracting liquid, and in order to maintain the solvent column at proper level this by-passed supply should, at all times, be substantially equal to the supply of solventto the said solvent column so that a continuous supply will enable continuous counter-current extraction and also that equalized pressure will always be maintained at opposite sides of said discharge conduit. To have counter-current extraction it is necessary that the solvent flow upwardly through the extraction column or tank I. To have that upward flowing, it would, conventionally, be necessary to provide a difference of level in the empty leg of the conveyor great enough to overcome the resistance presented by the material positioned between the discs of the extractor from the end E of the extraction section to the liquid level F. Such difference of level would require unusual length of the conveyor. To avoid this, I utilize pumps as hereinafter specified.

In the preferred form of my invention solvent is supplied to the column by a pump P above the liquid level, andthe by-pass conduit which extends from the bottom of the solvent column to the bottom of the extraction unitfis provided with' a pump P of a capacity substantiallyequal to the solvent supply pump P. It will be understood that in view of the maintenance of the substantially equalized pressureat opposite sides of the discharge outlet for the extraction unit, it will be unnecessary to provide, at such discharge outlet, a plug of such high density as would hold back liquid when discharging at atmospheric pressure,-but it will be necessary only to provide, in such'discharg'e conduit, a plug of a density suflicient to prevent the bypassed solvent at Ml fromat once passing downwardly through the discharge conduit, and it will be understood that I provide, adjacent to the discharge conduit, a zone of compressed exhaustedmaterial of a density only sufficient to prevent the passage of by-passed solvent directly through the discharge conduit or to provide a compressed er and the miscella outlet conduits 2|.

In Fig. 6, I have shown a modified form of my conveyor which is, in allrespects, similar to the construction shown in Figs. land 2, except that instead of the closely-spaced"projecting forkshaped carriers, I provide perforated partition conveyor members which operate in a manner substantially similar to that which-is hereinabove valve 15' to permit cutting in oroff the supply Fig. 1.

c" and this and other parts of the apparatus is substantially rectangular conveyor described as to Figs. 1 to 5 exceptthat the perforated solid partitions carry the solid material instead of projecting forked elements hereinabove specified.

In Fig. l, I have shown a gravity feed tankT 5. as an alternate form of solvent supply. This tank is,.as shown, connected by a pipe t with the solvent inlet conduit I8, there being provided in the pipe tbetween the tank T and the inlet conduit I8 .2.

It! from the tank T. I also preferably provide between the pump Pand theinlet conduit 18 a valve go so as to enable cutting off the solvent supply from the pump when the supply from the tank isbeing employed.

In Fig. '7 I have shown a modified form of m apparatus in which the conveyor i5 has, at its upper end, an inclined portion l5 in which the solvent-percolating or washing zone and draining zone are positioned in a construction somewhat 2U differing from that shown in Fig. 1. In this construction, a partition l6, similar to the-construction shown in Fig. 1, is provided above the solventlevel line S with a partlyvertical and partly in.- clined perforated partition I6, and solvent is supplied to conveyor leg l5 through a supply pipe 18* havingfinlets I8 l8. Obviously, when the partition I6 is perforated the solvent passing into the leg m will pass through the perforations in said partition and percolate or wash through the upwardly moving solid material in leg I5 I also preferably provide in the embodiment shown in Fig. 7, a solvent-collecting compartment or solvent-collector C in the form of an inclined pan or jacket which is mounted on the outer surface of the conveyor leg H5 and has a perforated wall C so that a considerable part of the solvent, after washing through the solid material moving upwardly in the ascending conveyor leg I5 will pass or drain through the perforated wall C into the collector C which is connected, at its lower end, with a conduit C communicating at C with the descending leg of the conveyor 15. It will be seen from the above, that the solid material which is being conveyed upwardly through the inill! clined portion of the conveyor to the outlet I l will. be more thoroughly washed with the solvent supply than in the case of the vertical construction shown'in Fig. 1. In other respects however, this construction is similar to that shown] in $0 .In Fig. 8 I have shown still another form of my apparatus whichis similar to and but slightly modified from the construction shown in Fig. 7. In this form of conveyor the upper portion is inclined further toward the horizontal than the construction shown in Fig. '7; also the perforated partition lfi iscut away or eliminated at the turn or elbow between the vertical and inclined sections of the conveyor so as to permit a more free passage 00 of solvent through the two legs of the conveyor; furthermore, the supply pipe it is provided with a series of three inlets instead of two. The solvent-collector C is mounted over a perforated wall 66 substantially 'similar'in all respects to the apparatus shown in Fig. 7. This solvent-collector also has a similar conduit C communicating at C with the descending leg of the conveyor.

In Fig. 9 I have shown still another modified 0 form of conveyor in which ascending and descending vertical legs are separated from each other and connectedby horizontal legs to form a structure. Conveyors of this type are in commercial use and li v, .3. A :m'ethod solvent extraction of solid materialsconsisting in it will, .th'erefore, be unnecessary to describe the inethod'of'supporting the same, it beingwsufiicient to state that theconveyorfelementsrare suitably driven, as for example by a suitably driveng'ear G to carry material from a horizontal leg up through an ascending vertical leg and thence through an elevated horizontal ,leg to an outlet suitably positioned btherein; tractor unitzisin sallirespects similarito the constructionshown in Fig;\ l. .However; the delivery box M", which is in all respects similar to the box M of Fig.=. l;udelivers' directlyto a'horizontallydisposed leg portion l I5 of" the rectangular. conveyor I I 5 shown in this figure, and solidimateria'l is conveyed through saidportion H5 and thence up .throughwthe ascendingileg 115" into and through a'washing zone H5 a draining zone H5 and thencethrough a horizontal: elevated portion to=an outlet H. fromiwhich' the material may .bersentwto as'uitable drier inotshown. "This construction is also preferably Iprovided withla solvent collector C which is preferably disposed at onewside :of a perforated wall section I i5 in. the ascending leg H5. a TheloWer-"en'd-of this'collector is similarly connected with 'arsolvent conduit Cicommunicatingat C 'with azdesceriding leg 5 of theconveyor, it being understood that in this construction also, the iasceriding. anddescendinglegsi 5a, ,I.|5. of the conveyor willbe filled with 1 solvent up to the solvent-level line, S Inlthis construction also; -I have shown a by-pass solvent-conduit or pipe connecting. thefdescend+ ing. leg with .the extractor unit,.-an'd as illustrated pipes 0 l (l and-a pump P are'. employed for this purpose. Inother respects the device is similar to thatshown inFig. :1. w 1

Having described my in'vention,I claim: r

s ='1-.;.A' method for. continuous *counter-current solvent extraction of solid materials consisting in providing an extraction column filled with solid material, continuously feedingrraw solid material through-one end, passing solid material through said column in, a substantially :vertical direction,

continuouslycompressing amassof solid material adj ac'ent; to, the discharge end, equalizing the hydrostatic pressure ,on oppositev sides of said'com- 2, A ;method for continuous. ,counterscurrent solvent extraction of solidmaterialsconsisting in providing an extraction column filledwith solid material, continuously, feeding raw solid material through one end, passingsolidsmaterial through said column, in a substantially vertical direction, continuously compressing a mass of solid material adjacent to .the: discharge end,m.equalizing= the hydrostatic ,pressureon :opposite' sides. of, said compressedmass byconnecting, at said discharge lend," a column of solvent, continuously discharging'saidcompressed material through said solvent column feeding solvent above said compressed massfrom, said column of solvent to the bottom of said extraction-column'in counter-current with said solid material, and conveying.saiddischarged material above the, liquid level in; s'aid' sclvent column. I n i i for, continuous counter-current providing an extraction column filled with solid material, continuously feeding raw solid material In this embodiment; the ex through I one end; passing solid material through saidv column inv a substantially vertical direction, continuously compressing a mass of solid material adjacentto the dischargeend, equalizing the hydrostatic pressure; on opposite sides of said compressed mass by connecting, at said discharge end, a column,ofsolvent,continuously discharging said compressed material through said, solvent column,

feeding solvent above said compressed mass from saidcolumn of solvent to the bottom ofsaid extraction column in counter-current with said solid. material, conveying said discharged material above the liquid levelin said solvent column, sup,- plying ,freshsolvent to said solvent column and percolating said discharged material with said freshlsolvent. i 4. Apparatus 'for continuous counter-current solvent extraction of. solidmaterials comprising an extractiontank having, at one end, a feeding inlet for-raw solid material and. at the. other end a discharge conduit for exhausted solid material, means, said tank adjacent to the discharge end thereof for compressinga mass ofsolid ma terial,, a ,combined material conveyor and solvent column connected with the discharge end ofsaid discharge conduit to equalize hydrostatic pressure at oppositessides ofsaid compressed mass'and cone veysolidmaterialthrough said solvent column, means for supplyingliquid solvent to said solvent column,-,and; a, by-pass conduit connecting the combined material ,con cyor and liquid column with thebottom of said-extraction tank-at a point between the saidcompressed massand the feeding inlet for solid. material of the extraction-tank. I Y

5. Apparatus. for continuous counter-current solvent extraction of solid materials comprising anextraction tank having, at one end afeeding inlet for rawsolid material and at the other end a discharge conduit for exhausted solid material, means within said tank adjacent to the discharge end thereof for compressing a mass of solid material, a combined material conveyor and solventcolumri connected with the discharge end of said discharge conduityto equalize-hydrostatic pressure at opposite sides of said compressed mass andconvey solid material ,through' said solvent column, meansfor supplying liquidsolvent to said solventcolumn, and a by-pass conduit connecting the combined material conveyor and liquid col- ;umn withthebottom of saidextraction tank, said ,combined conveyor and solvent oolumn having conveyor andsolvent-containing legs separated by a partition and provided,';at its upper end, with a solventinlet throughtheconveyor leg, said partition being perforated 'at its upperendto permit passageof solvent from one leg, tothe 6, Apparatus for continuous counter-current solvent extraction; of solid materials comprising an extraction ,tank having, atone end, a f eeding inletior raw solid material and at the other end adischargeconduit for exhausted solid material, means within said tank adjacent to the discharge end thereof ior compressing v a mass of solid material, a combined material conveyor and solvent columnlconnected with thedischarge end of said discharge. conduit to equalize hydrostatic pressure at opposite sidfi. 0f said compressed mass and conveysolid material throughgsaid solvent column, ,means for supplying liquid solvent to said solvent; column,and aby-pass conduit connecting thegcombined material conveyor and liquid column with the bottom of said extraction tank, said combined conveyor and solvent column having conveyor and solvent-containing legs separated by a partition and provided, at its upper end, with a solvent inlet through the conveyor leg, said partition being perforated at its upper end to permit passage of solvent from one leg to the other, and said'perforated partition having an upward extension above the solvent inlet to permit draining of percolated solvent.

7. Apparatus for continuous counter-current solvent extraction of solid materials comprising an extraction tank having, at one end, a feeding inlet for raw solid material and at the other end a discharge conduit for exhausted solid material, means, within said tank adjacent to the discharge 15 end thereof, for compressing a mass of solidmaterial, a combined material conveyor and solvent column having a washing and percolating section and connected with the discharge end of said discharge conduit to equalize hydrostatic pressure at opposite sides of said compressed mass and convey solid material through said solvent column, and a by-pass conduit between said solvent column at said washing and percolating section and said extraction tank above said compressing means at a point between the compressed mass and the feeding inlet whereby a supply of solvent percolating from said washing and percolating section is passed through said tank in countercurrent with said solid material.

MICHELE BONO'ITO.

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