US2074988A - Apparatus for solvent extraction - Google Patents

Description

March 23,1937. 'w'J. O'BRIEN ET AL I APPARATUS FOR SOLVENT EXTRACTION Filed July 2.1, 1934 a ma v Patented Mar. 23, 1937 UNITED STATES APPARATUS FOR SOLVENT EXTRACTION William J. O'Brien and Roy 0. Brett, Cleveland,

Ohio, assignors to The Glidden Cleveland, Ohio, a corporation of Ohio Company,

Application July 21, 1934, Serial No. 736,288

3 Claims. (Cl. 87- 6) This invention relates toa process and apparatus for extraction and recovery by means of solvents, and has particular reference to the extraction and recovery from oiland fat-bearing materials, such as cotton seed, sun flower seed, soy bean and other similar substances by the use of volatile solvents.

The methods heretofore employed for,the extraction of oils and fats by batch or continuous operation have embodied agitation of the materials, filtration of the solvents and decantatlon of the liquors carrying various quantities of the extracted substances.

Among the objects of this invention is the pro- Vision of a method and means whereby the ex traction and recovery may be carried out with greater economy and eiiiciency than heretofore practised and at the same 'time effect such extraction at temperatures below that at which damage would result to the extract itself or to any of the other constituents of the material subjected to extraction where it is desired to preserve the characteristics and qualities of such constituents.

A further objectof this invention is the prcvision of a process and apparatus whereby ap-- propriation may be made of the advantages which we have found are to be derived from subjecting-the material during the extraction to certain stages 'of treatment and in certain sequence.

More specifically, it is an object of this invention to provide a method and means for utilizing the special advantages heretofore set forth in the extraction and recovery of oils and fats from 'oiland fat-bearing materials, particularly soy beans, sun flower seeds, cotton seeds, etc.

Other, further and more specific objects of this invention will'become readily apparent to persons skilled in the art from a consideration of the following description when taken in conjunction with the accompanying drawing wherein We. have illustrated diagrammatically and in section a specific embodiment of the apparatus embraced in our invention. This apparatus comprises the vessel or chamber I having a frusto-conical bottom 2 from which the neck 3 serves as an outlet and means of communication with the other vessel or chamber E. A substantial portion of this chamber 4 is sur- 0 rounded by the jacket 5 through which suitable heating or cooling fluid may be circulated for the purpose of maintaining effective and proper temperature of the extraction solvent which is supplied through the pipe 6 and passes downwardly through the chamber 4 and then upward ly in chamber i. As illustrated in the drawing, in our preferred embodiment, 'the chamber l is vertical while chamber 4 is obliquely inclined thereto.

The chamber l is provided with a plurality of 5 agitators or stirrers I and 8 which are attached to the spindle 9, driven by the gear I!) connected to a suitable source of power. At the top of the chamber l the material to be extracted enters through the hopper II and is progressively fed by 10 the spiral conveyor I 2, operated by the gear l3 connected 'to a suitable source'of power.

An important feature of this invention is the special means we have provided for carrying solid material from the bottom ofthis chamber 4 15 onward to the top and subjecting this material to progressive stages of compression as it reaches the outlet at the top of this chamber 4. This special means comprises the spiral conveyor I4, the spirals of which have a uniform pitch from 20 the bottom to the point l5, but from the point l5 to the top thespirals gradually diminish in pitch. While solid material is traveling through the portion of the conveyor where the spirals are of uniform pitch there will be practically no com- 25 pression, but on reaching the spirals of gradually diminishing pitch the compression will begin and gradually increase toward the outlet. Further compression of the material before reaching the outlet of the chamber 4 is brought about by the inverted frusto-conical member l6 which fits into the upper part of the chamber 4 and makes the approach to the outlet of the vessel 4 of gradually decreasing cross-section. The conveyor l4 and member l6 are rotated by the gear l1 connected to a suitable source of power. The source of power forthe gear H as well as those for gears l0 and. I3 should allow a sufiicient range of speeds of these gears to meet the needs of operation.

In carrying out our extraction process, the ex- 40 tracting solvent is introduced through the inlet 6 and flows down the chamber 4' through the neck 3 and then upward through the chamber I to "the level A. An outlet i8 is provided at this level. The material to be extracted is fed from the hopper ll, drops to the surface of the solvent in the chamber i and gradually proceeds to the bottom of this chamber, forming a deep column through which the liquid is forced upwardly by the hydrostatic head of the solvent from the chamber 4. It will be noted that the solvent enters the-chamber 4 at approximately the level of A in chamber I.

We have found that superior results are ob- .tained if, instead of the solvent passing upward 55 1 through a continuous column of the material to i be extracted, it is passed through alternate zones of condensation andrarefaction of this material. This is accomplished'by means of multiple-arm 5 agitators I and 8. When these agitators are in operation, the material to be extracted and lying in the. zone C to D and the zone from E to the bottom which constitute the immediate vicinities of these agitators will be in a state of agitation and also rarefied instead. of concentrated and quiescent as is'the material in zones B to C and D to E which are remote from these agitators or stirrers. Consequently when operating these stirrers,

alternate zones of condensation and rarefaction of the material to be extracted are formed of the materlal undergoing extraction and the solvent will pass through these alternate zones against dif-'- ferent' resistances to its upward flow. We have found that more effective extraction is produced under these conditions.

We desire to have the distance between the agitators or stirrers of suflicient length to permit the formation of a column of the material in the zones of concentration and having enough depth to afiord a filtering medium to the solvent passing therethrough as well as supplying material from which one or more constituents are to be extracted. In the upper zone from A to B the material undergoing extraction is more rarefied than in zones B to C and D to E.

In the specific illustrations we have shown twoagitators but it is to be understood that any other number may be employed within the spirit and scope of this invention. Also, these agitators may be made adjustable with respect to location and angular direction, so that by proper positioning of the blades of the stirrers and regulation of the speed, the rate of feed of the solid material from zone to zone may be regulated and con- 40 trolled.

be completely washed and the extraction completed. As the'residue moves further upwardly beyond the point l5, it will be engaged by the spirals of gradually diminishing pitch and will be subjected to compression and the liquid will be I gradually forced therefrom. More liquid will be expressed when this material is forced between the wall of the chamber 4 and the frusto-conical member l6 so that on reaching the top outlet of the chamber 4; most of the solvent will have been '60 removed from the solid material.

The quantity of liquid entering the chamber 4 is controlled by means of a valve l9 su ably located in the feed line 6. Wit-hin the cham r I there is provided a screen-20 of suitable mesh to prevent the solid material passing out with the supernatant liquor through the outlet l8.

In carrying out this invention the material to be extracted is first prepared to permit a maxi- I mum penetration of the solve'nt and to eliminate as far as possible the objectionable condition of v fines.

In using our processior the extraction of oils from soy beans, sun flowerseeds and cotton seeds,

the specially prepared material to be extracted is first ted continuously onto the surface A of the 7 complete extraction of the oils. of the material to be extracted through the two preparing the material for effective extraction of the oil as the material passes through diminishing concentration of oil and solvent liquor. The slow precipitation of the material through this. miscella zone A-B tends to increase the concentration of oil in the miscella before decantation.

Second, the material is allowed to lie quiescent in the zone 13-0 to afiord complete saturation, and in this zone the material to be extracted serves as a flnal leaching bed through which the liquors rise. The relatively slow upward movement of the oil-solvent liquors does not disturb the fines entrapped by coarse particles of material being extracted, thus permitting a substantially clear miscella to be decanted.

Third, the material is gently agitated in the zone C--D before entering the second or initial Quiescent zone D-E by the agitator I to cause the liquors to ascend in a somewhat spiral path thus substantially avoiding a straight line path of travel. This gentle agitation also tends to expedite the extraction of the oils.

Fourth, the material is again allowed to remain in a quiescent state for further saturation of weaker oil-solvent liquors as said liquors slowly pass up through their initial quiescent zone Fifth, the material is again agitated by the agitator 8 which not only agitates the material to prevent a substantially straight line flow oi lesser concentrated oil-solvent liquors but also discharges the material into 'the cleansing orv Washing zone in chamber 4 after the oil has been substantially difiused and displaced from the cellular structure. This insures substantially The movement quiescent zones is eflected'by gravity.

Sixth, the material is now slowly conveyed up through a counter-current fiow of clear preheated solvent thus eifecting a thorough washing of the material with fresh solvent, the latter being introduced at or near the discharge point of the extracted material justbefore the extracted ma.- terial is subjected to a zone of pressing or squeezing action to remove substantially all of the solvent. This solvent is fed into the extractorunder sufllcient hydrostatic head to overcome the double leaching bed' resistance to control the flow of solvent so as to accomplish substantially complete and eflicient extraction and to eilect counter-current travel without substantially ailect-.

ing the efiectiveness oi the pressing or squeezing action.

Seventh, the extracted material is now sub- I jected to a zone of continuous pressing or squeezing in the upper part of chamber 4 to substantially free the extracted material of excess solvent before entering a suitable heated drying apparatus (not shown) for removing and recovering the balance of solvent in the extracted material; The drying apparatus may be any suitable standard equipment and, although an tion of the oils with solvent and sets up in a suitable apparatus a most effective method oi! accomplishing substantially complete extraction of materials economically and without affecting the suitability of the extracted material for other products.

Since the carrier of the extracted oils is solvent, sufficient time must be allowed for the solvent to penetrate the cellular structure of the vent in the extracted material. Also, the introduction of solvent and of the material to be extracted and the removal of'the liquor carrying the substances extracted and oiv the expressed residue are accomplished under conditions whereby escape of vapors from the solvent is r'erluced substantially to a minimum.

Although in the specific illustration we have set forth the extraction of fats and oils from oleaginous materials, it is to be understood that the apparatus and process herein set forthvand described are adapted to the extraction and recovery of various other products and materials as well as by-products,'when so desired. This invention may also be adapted to the treatment of materials of different specific gravity than the oleaginous materials herein set forth and also to the use of solvents of difierent specific gravity than those commonly employed for extracting the oleaginous materials specifically set forth herein I The present invention is not limited to the specific details set forth in the foregoing examples which should be construed as illustrative,

and not by way of limitation, and in view of the numerous modifications which may be effected therein without departing from the spirit and scope of this invention, it is desired that only such limitations be imposed as are indicated in the appended claims.

We claim as our invention:

1. In an apparatus for extraction by means of a solvent, a chamber having an inlet for material bearing the substance-to be' extracted and a plurality of agitators. vertically spaced from each other to provide alternate zones of condensation and substantial quiescence and zones of rarefaction and mild agitation of said material, a

second chamber having its lower portion in communication with the'first chamber, one of said agitators being of multiple-arm construction and disposed immediately adjacent to the bottom of the first chamber and the passageway from said first chamber to said second chamber so that when rotated the ends of said arms will cut across said passageway and thereby agitate and force the material from said first chamber into said second chamber, said second chamber comprising an upwardly-extending, elongated passageway, a spiral conveyor within said elongated passageway and disposed to convey material from the bottom of the first chamber upwardly through said elongated passageway, and means for introducing a solvent in said second chamber below the outlet from said secondchamber for the residue from the material subjected to ex traction, said spiral conveyor having an upper portion of the spirals of gradually receding pitch at the outlet for said residue to force solvent associated therewith back into said second chamber.

2. In an apparatus for extraction. by means of a solvent, a chamber having an inlet in the upper portion for material bearing the substance to be extracted and a plurality of adjustable agitators vertically spaced from each other to pro-.

'chamber and having its lower portion in communication with the first chamber, one of said agitators being of multiple-arm construction and disposed immediately adjacent to the bottom of the'first chamber and the passageway from said first chamber to said second chamber so that when rotated the ends of said arms will out across said passageway and thereby agitate and force the material from said first chamber into said second chamber, said second chamber comprising an upwardly-extending, elongated passageway, a spiral conveyor within said elongated passageway and disposed to convey material from the bottom of the first chamber upwardly through sai elongated passageway, and means for introducing a solvent in said second chamber be from each other to provide alternate zones of condensation and substantial quiescence and zones of rarefaction and mild agitation of said material, a second chamber having its lower portion in communication with the first chamber, one of said agitators being of multiple-arm construction having a configuration so that its path of revolution is in close conformity with the bottom of said first chamber and disposed immediately adjacent to the bottom of the first chamber and the passageway from said first chamber to said second chamber so that when rotated the ends of said arms will cut across said passageway and thereby agitateand force the material from said first chamber into said second chamber, said second chamber comprising an upwardly-extending, elongated passageway, a spiral conveyor within said elongated passageway and disposed to convey material from the bottom of the first chamber upwardly through said elongated passageway, and means for introducing'a solvent in said second chamber below the outlet from said second chamber for the residue from the material subjected to extraction, said spiral conveyor having an upper portion of the spirals of gradually receding pitch at the outlet for said residue to force solvent associated therewith back into said second chamber.

WILLIAM J. OBRIEN. ,ROY c. BRETT.

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