US2491115A - Method for solvent extraction - Google Patents

Description

Dec- 13 1949 c. R. KlNcAlDE METHOD FOR SOLVENT EXTRACTION 2 Sheets-Sheet 1 Filed Nov. 27, 1943 C. R. KINCAIDE METHOD FOR SOLVENT EXTRACTION Dec. 13, 1949 2 sheets-sheet? Filed Nov.l 27, 1943,

v INVENTOR. down fo Glade.

a 6AM/nfs R. /r/NcA/DE Patented Dec. 13 1949 lU'NITED .STATES F FICE METHOD* EUR SOLVENTEXTRACTION! Charles R; Kincai deHouston.Tex. ,Application November 27, 1943, SerlalNo.A 511,969

1 Clam. (Cl. 26h-412.8).

Theinvention relates to a meansy and method of solvent extraction of oils. fats, waxes, gums', resinsJr etcetera, fr oirr solids` such as seeds-beans, and' vegetable` bre as tv ,ellv as those of' animal and mineraljorigin,

It has been found' that the success of` asolvent extraction*proessgenerally depends upon conducting the process, ina Aminimum lof time'Y at a' temperaturesomevvhat'below that at whichdef composition sets in' so as to avoid initiating` such decomposition, 'on the onehand andthe discoloration ofi both the extractiva, andV the meal on the other hand.f

The termL raw Solids* used: todesienate vegetable, animal. andi mneralsfrom; which oils, fats( waxes gums, and resinsrmay be removed by a proper solvent; extractve will be usedfes descriptive of' the large" class off,materialsl which mayv be recovered by solventextracton; meal or clean solids will be used for thejbre or solid matter remaining; and rainate designates, the homogeneous liquid' Vsolution of' extractive in solvent.

The present application is a` continuation-inf part of prior copending application Serial No. 344,770', l'ed July 1,0, 19510,v` for a Method and apparatus for solvent extraction. and also re; lates, to the, subject matter of @pending aP.- plication Seriallllo. 512,053, filed. November 21, 1943; for Method of'producing ehlorinatedhydrf carbons, both'now abandoned-` Itis one ofthe objects of the presentinvention to provide a solventexl'fractionprocessiwherein a. solvent .i is.n agitated in intimate Contact, with raw solidsA in a finely, divided@ state so asto, re,- move the desired extrective.,.andv to thereafter treat the resultingraffinate,tore'claimthe..solvent for reuse and rereulation.

' Another obj ect. of the,inventionis. to providea closed system `vapor tghtsolvent ,extraction apr paratus wherethevraw solidstaleagitatedin the presence of a couriterilovv.v of. solvent to produce a rich rainate.

Another` object.. ofj the vinvention is.,-.to ,provide a vpluralityv of chambers. for. contact, and.. agitation of the solids andsolventwheren.thesolids are exposed to av plurality of. separate, applications of the solventjt'o each chamber tforemove the extractive,

Still another object oftheinvention tonnovide anextraction orJ contact chamber where the agitation is appliedby threedistinctI ty-.pes ofi flightsso as to obtain the desired rate of uniformmovement. VWhile firstimmersing' `the material in the solventand thereafter washing the material with 4solvent to obtain themaX-imum efciency .of vsolvent on the one handand the maximumV removal of l'the extractiva onthe other -handl -Anotherobject ofthe invention is to filter the rich-raffinate aty atmospheric temperature to ef- `rect the removal oifsolid'sv and-collodial matter .incombinati'on with a neutralizationof the ex- -tractive-.so 1as'y 11o-polish the extractiva andavoid any ldeeolori-'zi'ng treatment.

Another object: istoprovide alight conveyor orlintimat'e associationoff-the ravvv material and solvent to: produce al` rich rr-a-natewherein the oonveyonisbrush tipped` to 'insurea wiping acf- -tiorr` againstA 'the 4chamber AWalla Another 'object' is to conduct; asimple and economical process ofrsolvent extraction Where aaminimum-Yof heat isl applied to-'theextractive soasetoA avoid decomposition: a-nddiscoloration andfilteringy offthemeal is eliminated.

AnotherV object is to Yneutralize and clarify the rich rainate prior to the application of Y anv-y heat'.

Other andl further objects ofthe invention will. be readily apparentI from thev :followingl dei scription wherein- Figi lyis a diagrammatic View partly in section illustratingL an embodiment ,of the apparatus ready fory operation.

lligiqZv` is a sectional View through one of* the extractors showingthe novel agitating'multiple flight" conveyor construction utilizedjin' thelnventiorr.l

Fig;VY 3f is a sectional viewthrough thecontinuous press-*for removing` excess liquid fromy theexftracted solids;`

Fig; 4r is a sectional View' throughthe flash Atovverj or still" for` separating the railinateiinto solvent` andL solute. v

Fig; 5 lis asectional viewA throughvthe,J stripper tower which constitutes an element of the. exftraction, system.

Referringl to.. the drawingstheinumerals. I and refer to successive.. extractora which. are op.- positely inclined and whichw have their. spaced ends interconnected by means of a pipe 3. Each of these extractors is provided with a special agitator conveyor 4 (Fig. 2) driven from a suitable source of power (not shown) to agitate and carry any solids from the lower ends of the extractors for discharge at their respective upper ends'.

A The agitator conveyor 4 is of special construcstruction to eiect an intimate association of the solids and solvent and comprises three distinct conveyor ight sections 5, 6 and 'I which are so designed as to provide agitation and conveyance at a desirable rate of travel of solids within the cylinder 8. The lowermost section 5 of the agitator conveyor 4 is a section of solid ight which is designed to move and fold over the solids in the solvent in the lower end of the extractor chamber thereby preventing packing or clogging of the solids at this point.

The section 6 of the agitator conveyor is a section of a cut-and-folded ight in which the sections 9 and I 0 are severed and anged outwardly so as to provide surfaces which agitate and lift the solids to effect more vigorous and intimate mixing contact with the solvent while at the same time conveying the solids upwardly toward the ribbon type of iiight I which, due to its open or skeleton construction, permits the incoming Vatomized solvent at 2| to move against or countercurrent to the movement of the solids.

The solids to be treated have been prepared by crushing, aking, grinding or otherwise, so that the surface of the particles will present the maximum exposed area for contact with the solvent. These solids will be deposited in the hopper I5 and fed into the extractor I so as to be moved .through the extractor cylinder by the conveyor 4.

The solvent from the storage tank I8 is conveyed by the pump through the pipe I9 to be atomized or sprayed upon the solid matter by the nozzles l2I. The solvent will be sprayed into :the extractor at such a rate that there will be an accumulation thereof in the lower portion of the extractor and preferably the horizontal level of the liquid may be about half way up the in- .clined extractor.

When the solvent is mixed with the solid matter and removes the extractive therefrom it is thereafter known as ranate and there will be .a bath of this rainate in the lower part of the :extractor so that the first operation is the immersion of the particles in the raii'inate bath. They will be agitated and conveyed by the solid flight 5 and gradually moved upwardly along the cylinder until they arrive at the cut and folded sections 9 and I 0 where the agitation is substantially increased. At about this level the solid matter moves out of the bath and the additional agitation tends to allow the raiiinate to drain from ythe particles. As the particles move along in the cylinder they arrive at the ribbon type conveyor I which additionally agitates the particles and they are subjected to a washing action by the atomized solvent distributed by the sprays 3l. It seems obvious therefore that the solids have been subjected to at least two contacts with rst the rafnate and then with the solvent so that a substanial part of the extractive borne by the particles is removed therefrom. The solid matter after having been washed passes through the pipe 3 into the second extractor where the opera- `tion is repeated. The solvent gradually being converted to raflinate as it contacts the solid, moves down the extractor cylinders by gravity in a counter current flow.

n, al

The rich raflinate which has absorbed a substantial portion of the extractive is drawn off through the pipe 30 at the lower end of the extractor I while the weak raffinate is picked up by the pump 25 and conducted through a pipe and the iilter 26 which is connected to the pipe I9 so that the weak raffinate from the second extractor is recirculated in the desired proportion with the incoming solvent in the extractor I.

In a similar manner the liquids removed from the mechanical dryer I'I, to be more fully described, are conducted by means of conduit 21, lter 28 and the pump 29 to the nozzles at the upper ends of the extractor I to be recirculated.

Following the rich raiiinate as it leaves extractor I through the pipe 30, it will be passed through a suitable filter 3| which is utilized for the purpose of removing any solid or colloidal matter carried bythe raiilnate. One of the essential features of the present process is to minimize the time in which the solvent is in contact with the solids andit is desirable to remove all of the solid matter from the raii'inate prior to the application of any heat thereto so as to avoid discoloration or decomposition. The pump 32 carries the raiiinate from the filter 3| into the chamber 33 which may be designated as a neutralizer and clarifier, there being an attachment on this clarier 33 whereby suitable material may be added to neutralize, clarify and dehydrate the raffinate. An illustration of such a material is pulverized quick lime and calcined diatomaceous earth mixed together in substantially equal parts. This chemical is added and l mixes with the raflinate as it continues its course through the pipe 30. The filter 34 then removes the added material so that the raiiinate passes on to a preheater 35. With this procedure the rafnate is prepared for heat treatment and it should be particularly noted that all of the operations so far in the removal of the extractive and treatment of the rainate, that the process is carried on at atmospheric temperature and pressure so that no decomposition or decoloration of the extractive has occurred.

The ranate could be conducted directly into the flash tower 36 and thence to the stripper tower 31, but it has been found to be desirable to Vpreheat the raffinate and the preheater 35 i therefore comprises a cylinder 38 having the heater tubes 39 therein which are supplied with steam through the connection 40 from the boiler 4I. The rainate coming in contact with the heated tubes 39 is raised to the desired temperature and moved by the pump 43 through the pipe 42 to the nozzles 50 in the top of the flash tower as seen in Fig. 4.

This ash tower has a plurality of partitions or trays therein such as 5I provided with the bubble caps 52. The raffinate moves downwardly in succession over the trays 53, 54 and 55, each of which is provided with a heating coil 56. The

temperature in the flash tower approximates 212 F. The solvent used preferably has an initial boiling point of approximately F. and an end boiling point of approximately F. so that the temperature in the flash tower is substantially in excess of the end boiling point whereby the solvent will be instantly vaporized from the rich rainate entering the ash tower. Such a solvent and the production thereof comprise the subject matter of copending application Serial No. 512,053, to which reference has above been made. In this manner there will be no tendency for the various constituents making up the solvent to vaporizefindependently at their fpnnvarious-'boiling aciritsbetween .190 ,and 175 during whiclrtheextractive is subjected to heat is a minimum so as to prevent decolorizationlror even tneinitiationof .decomnesiticn- .The vaporized solvent rises .instantly the f ilash' tower' and escapes tlirQllgrh ther' Outlets? finto inc .condenser .5 8 whichissuitebly led by the provision .oi the pines Ytlieleirl SD .esto :eiect condensation `cf, the sel. .It and' its' retlin through the pipe 39 to the solvent storage tank I8.

The extractive moving down through the flash tower is conducted through the pipe 6I by the pump 60 into the stripper tower 31 which is seen in section in Fig. 5. This stripper tower has the trays 63 and the coil 64 whereby steam from the lines 65 may heat the coils and vaporize any residual solvent from the solid material. The lower portion of the stripper tank is jacketed with the coils 66 and provided with an inclined bottom so that the extractive will be directed through the outlet 10. The vaporized solvent will pass through the pipe 1| into the condenser 58. The extractive will be free of solvent, it has been discolored and initial decomposition has not set in so that the additional steps of treating the extractive for the purpose of clarification, decolorizing and dehydrating are unnecessary. It might be stated that with other solvent processes where the rich raffinate is not filtered, claried, neutralized nor dehydrated prior to vaporization that some of the solvent and colloidal therein tends to cause decoloration or decomposition of the extractive when it is heated.

One of the essential features of the present process is that in the iirst place the solid matter is maintained in contact with the solvent at atmospheric temperature for a minimum period. The rich raffinate thus formed is then immediately ltered to remove any solid or colloidal matter. It is then neutralized, clarified and dehydrated, all prior to the application of any heat. The pecularities of the solvent in that it has an end boiling point below the temperature at which decoloration and decomposition of the extractive sets in permits the operation of the process in such a manner that the extractive is not discolored nor is decomposition initiated. The vaporization of the solvent occurs instantly so that the extractive is beneted thereby because it has been found that too long a contact of the extractive with the usual type of solvents and a prolonged period of heat tend to destroy and discolor the extractive.

As best seen in Fig. 3 the solids passing through the pipe I6 are deposited upon an endless foraminated conveyor which cooperates with a shorter conveyor 16 and a plurality of rollers 11 to adjustably apply pressure to such solids and thereby squeeze a major portion of the residual solvent from the solids. This solvent, as already explained, is conducted from the dryer through the conduit 21.

The solids discharged from the dryer I1 pass through a steam jacketed pipe 80 to the first of a series of reclamators 8l which are surrounded by a steam jacket 82 supplied with steam from the boiler 4l through the steam line 83. Any residual solvent remaining in the solids passing through the reclamators 8l is vaporized and is conducted from the respective units through the vapor line 84 and to the condenser 58 so that f' .will Ibex-condensed:'andzretiirned+159 thesolventstoragatankd8; 1hr-order that;the-cleanL solidsiishall; be .uniform and freeirbm tracesi yofthe .-.rsolventnsed in .the

process; e ch off `.the reclamator. .chambers .-8 I is fprovided with:faspecialeconyeyor 851:.driven. from a suitable source ffpower .(notnshwn). Eachpf mounted upon a shaftifTI-,fltheilflight.beingmaintainediifspa'c'ed relation Witheach the shaft fand the inner walls of the surrounding chamber :8L In?orderltolagitateTand convey the solids within the chambers and to :avoid caking of the solids to the inside walls of the chambers at any point therein the flight 86 are provided with fringed outer edges which are normally of slightly greater diameter than the interior walls of the chambers and which possesses such resiliency that the fringe 88 maintains const-ani; brushing yor scraping action on the inside walls of the reclamator cha-mbers. In this manner any tendency of soilds to stick to the chamber is overcome as the 'solids are constantly moved toward the outlet 90 whence the clean solids are conveyed in any suitable manner to storage for use in commerce.

The solvent per se is being described and claimed in my copending application Serial No. 512,053 heretofore mentioned, but generally for the purposes 'of the present disclosure it may be stated that this solvent has no color, is water white, is non-explosive, non-iniiammable, it has an initial boiling .point approximating F., an end boiling point of 'approximately 175 F., a -weight approximating 11.288 lbs. per gallon, the maximum vapor pressure at recovery is 10 lbs. and a latent heat of evaporation approximates 192 B. t. u. .per pound. It is impossible to determine the molecular of weight because it is -a miscible solution of a large number of chlorinated hydrocarbons formed from the isomers of the hydrocarbons with chlorine which produces many different compounds having individual boiling points which overlap leach other, but which it is impossible to separate into the different constituents thereof by any form of distillation.

As just indicated no heat is applied to the soluble constituents until all solids have been removed therefrom. In a similar manner no heat is applied to the 'solids until such solids have passed through the mechanical dryer i1 and into the reclamators 8l. The treatment of the solids in the reclamators removes all of the solvent in a manner and at such temperature that the clean solids withdrawn from the outlet 9U are likewise of higher quality.

Brloadly the invention comprehends a continuous system and method for solvent extraction of the soluble constituents of raw solids so that liquid and clean solid products of higher quality are obtained from the raw solids.

What is claimed is:

A solvent extraction lprocess including the steps of effecting an intimate mixing of iinely divided .particles of oil bearing material by immersing the particles in the solvent, agitating the mix while gradually moving the solids out of the raffinate thus formed, washing the solids by spraying solvent thereover while agit-ating the solids, withdrawing the rich raiilnate thus formed from the area of immersion, drying the solids and vaporizing the solvent therefrom to discharge dry extra'ctive -iree solids, polishing the rich raii'inate by filtering to remove any solids or colloidal matter therefrom, treating the ramnate for effecting 7 8 neutralization, clarification and decolorization all REFERENCES CITED prior tothe application of other than atmospheric The following references are of record in the pressure or temperature thereto, reflltering the rafElna-te, subjecting the ranate to flash heating me of this patent' for a. minimum period S0 'as t0 avoid any Sub- 5 UNITED STATES PATENTS stanltial setting in of initial decomposition and Numb Na Da above the end boiling point of the solvent to n- 1 194%115 Handyme Aug atelgls stantly vaporlze the solvent without discoloring 1748356 Lawren Febl'zs 1930 the extractve, condensing the solvent for recir- 2158427 Reichert May 16 1934 culetlon and Stripping the extractive of any re- 1o 2271605 Swanen an 7) 1941 mammg Solvent' 2,278,647 Cyphers Apr. '1, 1942 CHARLES R KINCAmE-V 2,390,388 Rector Dec. 4, 1945

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