US2200983A - Extraction with solvents - Google Patents

Description

May 14, 1940- c. F. DINLEY EXTRACTION WITH SOLVENTS m5 mm INVENTO R CZarenaeEDmZey, BY M TTORNEYS.

Original Filed Jan. 5, 1937 Patented May 14, 1940 EXTRACTION WITH SOLVENTS Clarence F. Dinley, DctroihMich alslgnor, by

mesne assignments, to Solvent Machine Oompany, trustee, Michigan Detroit, Mich, a corporation of Original application January 5, 1937, Serial No.

Divided and this 21, 1937, Serial No. 149,360

appl bation June Claims. (a, 260-105) My invention relates to the extraction and recovery of oil, fat, or the like, from organic material with solvents, and to apparatus for this purpose. The organic matter treated may be 5 either vegetable or animal. My invention is very useful, for example, in the extraction of oil from soya beans, or other beans or seeds, or in the extraction of oils or fats from carcasses or parts of hogs or other animals, and also in the treatment of garbage for the recovery of various oils, fats, or other greases which it may contain. It may also be found useful for extracting various essential oils and resins from the material containing them, such as winter green, peppermint, etc. Other features and advantages of my invention will appear from my description hereinafter of a species and form of embodiment, and from my drawing. All the features herein shown or described are, indeed, of my invention, so far 20 as novel over the prior art.

This application is a division of'my application Serial No. 119,076, filed January .5, 1937, now Patent No. 2,097,147, and covers particularly the process and apparatus therein disclosed for ex- 25 traction with solvents. This process and apparatus can be employed with volatile chlorinated solvents, under stabilization as more particularly set forth and claimed in my said application, with the important advantage that when thus stabil- 30 ized, the chlorinated solvent does not decompose appreciably, so that drawbacks due to such decomposition are avoided. Volatile chlorinated solvents are exemplified by trichloromethane, tetrachloromethane, trichlorethane, tetrachlor- 5 ethane, trichlorethylene, and tetrachlorethylene amongst the chlorinated aliphatics, and amongst aromatics by chlorobenzene, and even para, meta, and orthodichlorobenzene-although these latter are close to the upper limit of volatility. How- 40 ever, a greater variety of solvents may be used, according to the material treated-the choice being no means limited to chlorinated solvents.

In the drawing, Fig. I is a diagrammatic side view of the system of apparatus suitable for the 45 process of extraction according to my invention.

Fig. II shows a cross-section through part of the apparatus, taken as indicated by the line and arrows Il'II in Fig. I.

Fig. III'shows a similar cross-section through 50 another part of the apparatus, taken as indicated by the line and arrows III-III in Fig. I.

For treatment with the solvent, the organic material should preferably be brought toa suitably fine state of division; and for this any suitable method may be used, according to the charits bottom,such as tubes l8 for the circulation of acter of the Soya beans, for example, may be finely flaked; or they may be crushed or ground with any commercial machinery suitable for the purpose,to such fineness that at least 90% will go through a -mesh sieve.

The finely divided material passes through a chamber or apparatus A in which it is brought in contact and saturated with clean solvent, and then through a chamber or apparatus B in which the solvent is separated or dried out from the residue of the material. For this purpose, a tubular channel or conduit 0 extends through the chambers A and B, and means such as an Archimedes screw II) is provided for feeding the crushed soya. beans or other material to be treated 16 from a receiving hopper II at one end through the tube C to the discharge at the other end or the tube. The portions of the tube C outside of and between the chambers A, B may be of metal or other impervious material; but the portion l2, l3 in the chambers A, B are of finely foraminous or porous character permitting passage of liquid or vapors through the tube walls. Along and above the tube portions l2, I3 extend metallic or other impervious side walls I, ll -and l5, l5, forming in each case a trough with the tube at its bottom (see figs. 11 and 111).

Pure solvent from any suitable source (represented in Fig. I as a condenser D) supplied through a (valved) pipe l6 fills the trough It in chamber A, percolates through the corresponding porous tube section I! and the material therein, leaching out its oil, fat, or the like, and runs down into the bottom of the chamber, whence it may drain or be drawn away through a (valved) pipe I! to any suitable grease and solvent separating and recovery plant, here represented by a distilling vaporizer E. As shown, the chamber A is provided with heating device(s) or units in hot water (or steam), to maintain in the chamber a temperature preferably approximating but not exceeding the boiling point of the solvent used. Provision is made for cooling and condensing the solvent vapor on the wall of the upper part of the chamber A, as by means oi'an external jacket l9 through which cooling water may be circulated. The pure condensed solventrunning down the cooled inner wall of the chamber A collects in a wall-trough or gutter 20, which returns it to the trough M at either end of the chamber.

In the chamber B, the upper half of the tube C is preferably omitted, so that the lower half and the sides l5, l5 form an open round-bottomed trough in which the solvent evaporates or 55 may be of any suitable type.

dries out of q the crushed soya beans or other material treated. For heating the lower portion of the chamber B, there are heating device(s) or units 22 in its bottom and along its sides, such as tubes for the circulation of steam. In addition, the bottom wall of the chamber B may have a steam jacket 23. In the upper part of the chamber B, the vapor is condensed on the wall by an external cooling jacket 24, and runs down into a. wall-trough or gutter 25, as in the chamber B. Instead of being returned from the gutter 25 to the trough l5, however, the condensate is led off through a valved pipe connection 26 into the pipe I1, and thus drained or drawn away to the vaporizer E or the like. Any liquid in the bottom of the chamber B is led off through a valved pipe connection 21 into the same pipe [1. As shown, there are sloping metal baflle plates 28, 28 extending from each upper edge of the trough l5 nearly to the sides of the chamber B, just above thetom. As shown, provision is also made for in-.

jecting live steam into the liquid in the vaporizer E, through perforated piping 3| near its bottom, for the purpose of steam-distilling the liquid. The solvent vapor evolved in the vaporizer E may be led through a pipe connection 33 to the (surface) condenser D already mentioned, which From this condenser D, the purified solvent is led back to the trough II in chamber A through the pipe l6, as mentioned above.

Preferably, the feed screw I0 is generally of such pitch as to feed the crushed soya beans or other material through the chambers A and B quite loose, in a layer not more than about half filling the tube C. As the screw l0 revolves, it agitates and kneads the loose material, so that new surfaces are continually opened up and presented to the percolating solvent. At and near the ends of the chambers A, B (and in the part of the tube C interconnecting them), however, the feed screw Ill may be of considerably reduced pitch, so as to pack the material sufficiently to fill the entire cross-section of the tube and prevent or minimize ingress of air or passage of solvent vapor from chamber B to chamber A.

In'operation, the temperature in chamber A should preferably be kept about (or not over) the boiling point of the solvent used, to secure maximum dissolution of the oil, fat, or the like by the solvent and avoid boiling the latter. In the chamber B, the temperature should preferably be kept well above the boiling point of the solvent, in order to vaporize it and dry out the residue of crushed soya beans or other material treated. Using trichlorethylene as the solvent, this would mean about 188 F. in chamber A and ZOO-212 F, in chamber B.

If desired, a vacuum may be maintained in the chamber B and in the vaporizer E-either or both-as by connections to condenser D, or any other suitable means. Solvent may or may not be boiled in chamber A. In chamber B, the tube C (and trough l5) may if desired be specially heated, as by any suitable heating means externally carried by it, or included in its wall.

In using chlorinated solvents for extraction treatment according to my present invention, it is very desirable to prevent corrosion or other such action on metallic parts or apparatus that may be exposed to the solvent in the extraction process, and to prevent the evolution of dangerous fumes, which may injuriously affect workers, and may render the vicinity of the apparatus uninhabitable. Such corrosion and fumes may result from decomposition of the solvent when heated under the conditions obtaining in the treatment of vegetable and animal matter of various kinds for the extraction of oils, fats, or greases, either from contact of the solvent with air or moisture present in the matter treated, or in the apparatus, or from Y other causes. Moreover, decomposition products from the solvent may in some cases affect obj ectionably the oils, fats, or greases which it is desired to recover, or may react in undesirable ways with the residue of the organic matter treated.

To some extent and in some cases, the objectionable effects of decomposition of the solvent may be prevented by the presence therewith of solid alkalis, preferably water-insoluble or nearly so (such as limestone, marble, or other forms of calcium carbonate), or, better still, by the use of solid stabilizers which do not vaporize. But while such substances perform their function very well in the liquid solvent, their influence is not very effective in the vapor of the solvent, and it is especially in the vapor phase that the solvent decomposes, and that. acid and/or (free) available chlorine are formed. Best results are obtained, therefore, by carrying out the treatment in the presence of a reagent that is of such volatility as to vaporize with the solvent, and that will stabilize the solvent vapor or counteract the objectionable decomposition, partly, perhaps, by beingitself readily chlorinated, or by neutralizing deleterious decomposition products in the vapor, but mainly or in large measure by preventing the usual decomposition of the solvent (1. e., stabilization in a stricter sense). Whatever its action,the stabilizing agent employed should, of course, be compatible with the undecomposed solvent, so as neither to react with it under the conditions of use, nor to be driven off or separated from the solvent. That it should not boil so much below the solvent as to be driven off by the heat is also implied in its compatibility with the solvent, as well as in the statement that it vaporizes with the solvent. This last statement also implies, of course, that the stabilizer volatilizes without being itself decomposed by the heat. A great many organic substances such as hereinafter indicated are known to chemists as having suitable properties.

Besides the correlation of the stabilizer with the solvent as above indicated, the stabilizer (as well as the solvent itself) must, of course, also be correlated and compatible with the organic material treated. In other words, the stabilizer must not react either with the oil, fat, or the like to be recovered, or with the rest of the organic matter to be treated; nor must it be of such character that its presence would be seriously objectionable in the product(s) to be recovered, or in the residue(s) from the extraction operation. If it tends to remain with either of these products in more than negligible amount, it should be of such character that it can be eliminated from them, without excessive cost, by suitable steps or operations. Of course, the great variety of organic substances which it may be desired to treat with chlorinated solvents for purposes of extraction preclude broad generalizations as to the suitability of stabilizers from this angle.

Examples of a type of stabilizers that appear to be effective in part by neutralizing the (chicrine) acid, as well as byundergolng' chlorination, are the alkaloids-such as berberine, caifeine,

quinine, cinchonine, cocaine'-either in pure or crude forms. Alkaloids are soluble in chlorinated solvents and impart to the solvent an alkaline reaction when used in suflicient proportions, such as hereinafter indicated. While alkaloids are not volatile like other types of stabilizers hereinbefore and hereinafter referred to, and do not vaporize freely with the solvent as mentioned above, yet they tend to minimize the presence of available chlorine (acid) in the solvent vapor, besides eliminating it from the liquid solvent. Stabilizing influence of non-vaporizing stabilizers (such as alkaloids) in the solvent vapor may to a degree be due to a peculiar sort of volatilization of such stabilizers when dissolved in the boiling solvent. However, the amount of non-vaporizing stabilizer thus disseminated and carried in the solvent vapor is at best very minute as compared with the substantial proportion vaporizing or distilling with the solvent when the latter and the stabilizer boil at temperatures suiiiciently close together.

Alkaloids being in many cases relatively inert, their presence in extraction products or residues may in many cases be unobjectionable, except, of course, when the product or residue is to be used for food, when the bitterness or other strong taste of many alkaloids might be offensive.

Another class of stabilizers that neutralize acid. and also undergo chlorination, are the volatile organic bases, and particularly volatile amines and basic cyclic organic compounds characterized by nitrogen in the ring, as well as a few volatile organic bases which appear to owe their alkalinity to the presence of phosphorus in the molecule. These are soluble in chlorinated solvents and impart to the solvent an alkaline reaction, when used in such proportions as hereinafter indicated. Amongst the amines, I may particularly instance diethylamine, benzylamine, triethylamine-although there are a very large number of amines that are volatile in the boiling range of chlorinated solvents, up to C. or even C. In general, I prefer the tertiary amines, characterized by the nitrogen radical. Amongst the cyclic organic compounds, I may instance the pyridines, such as pyridine itself, methyl pyridines or picolines, and ethyl pyridines; pyrazine, pyrimidine, and piperidine; and pyrollic or pyrolle type bases such as pyrroline, pyrazoline, and pyrrolidine. In some cases, of course, the persistent odor of pyridine or the like might be objectionable.

Another class of stabilizers consists of the essential oils, which are volatile, are soluble in chlorinated solvents, including trichlorethylene, distil or sublime with water, and besides being chlorinatable appear to prevent or inhibit the usual decomposition of the solvent vapor, or at least obviate corrosion of metal, etc., as a result of such decomposition. Of these I may instance camphor, turpentine, pine oil, oil of Wintergreen, oil of lemongrass, oil of citronella.

The essential oils are not so readily volatile as many of the organic bases, although thewater commonly present with chlorinated solvents assists somewhat in their volatilization. In general, these substances have decided but inoffensive odors, so that they may in some cases advantageously be used along with odorous organic bases (such as pyridine, forexample) to disguise objectionable odors of the organic bases. They have the special advantage that they can be readily and thoroughly steam-distilled out of the extract resulting from treatment of organic matter with them, for the purpose of finally recovering the extracted oil, grease, or the like and purifying the solvent for re-use. Moreover, any last residue of essential oil remaining in the extracted product after recovery in this manner does not render the product odorous, as would organic bases.

In cases where essential oils are themselves to be extracted by means of chlorinated solvents, the essential oil so extracted itself serves as a stabilizer; so that the solvent only requires a small amount of stabilizer added before use, to prevent decomposition before it has taken up any essential oil from the material treated. When chlorinated solvents are used for the extr ction treatment of soya beans, essential oils m y advantageously be used as stabilizers, and particularly turpentine, oil of citronella, or the like.

In practice, it is, of course convenient to add the stabilizer to the solvent before use of the latter, and it is therefore preferable that the stabilizer should be soluble in the chlorinated solvent, as is the case with the stabilizing substances hereinbefore mentioned. The amount of organic stabilizer added to the solvent must,

of course, exceed what is required to neutralize any initial acidity of the solvent. In general, an addition of anywhere from about M, of 1% to 1 /2% by weight will be found sumcient, particularly in the case of alkaloids. However, larger proportions may sometimes be usedz e. g., to 5% of pyridine, which has no effect on steel; although in excess it will slightly tarnish highly polished brass. Such proportions of organic stabilizer generally sufilce to maintain an admixture thereof with the heated chlorinated solvent over an extended period of use of the solvent, involving treatment of a series of batches of organic material therewith. The solvent will not cause corrosion or other deleterious action due to acid, nor give off objectionable fumes, as long as any of the stabilizing ingredient remains. The stability of the solvent may be extended indefinitely by repeated timely additions of the organic stabilizing agent. Stabilizers which boil sufliciently close to the boiling point of the solvent with which they are used remain with it from the treated material, which process com' prises continuously and successively feeding the organic material into, through, and out of closed treating and solvent removal chambers, and providing liquid solvent in the treating chamber for the treatment of said material; in said treating chamber continually heating and vaporizing the liquid solvent and condensing the vapor, and

percolating the condensate across and through the traveling material in said chamber; in said solvent removal chamber continually heating the traveling material and thereby vaporizing out the solvent remaining therein, while leaving a region of the chamber substantially unheated; oontinually condensing the solvent vapor in said-untreatment of organic material containing oil,-fat,

or resin, and the removal of residual solvent from the treated material, which process comprises continuously and successively ieeding the organic material into, through, and out of closed treating and solvent removal chambers, at an intermediate level therein, and providing liquid solvent in the treating chamber for the treatment of said material; continually heating a.v volume of the liquid solvent in said treating chamber, below said level, thereby vaporizing the solvent; continually condensing the solvent vapor in said treating chamber above said level; continually percolating the condensate downward through the traveling material in said treating chamber, and returning it to said volume of liquid solvent; continually heating the traveling material in said solvent removal chamber and thereby vaporizing out the solvent remaining in said material, while leaving the region of the chamber above the traveling material substantially unheated; and continually condensing the solvent vapor in said upper unheated region, and withdrawing the condensate therefrom-out of the chamber as liquid.

3. A continuous process for the extraction treatment of organic material containing oil, fat, or resin, which process comprises continuously feeding the material into, through, and out of a closed chamber, and in said chamber providing and continually heating and vaporizing liquid solvent for the treatment of said material; and condensing the solvent vapor in said chamber and percolating the condensate across and through the traveling material, so that the material continuously traversing the chamber is continually acted on by fresh, uncontaminated solvent.

4. A continuous process for the extraction treatment of organic material containing oil, fat,

the treatment 01' said material; continually heating a volmne oi the liquid solvent in said chamber below said level, thereby vaporizing the solvent; continually condensing the solvent vapor in said chamber above said'level; and continually percolating the condensate downward through the traveling material, and returning it to said volume of liquid solvent; so that while the content oi. extracted matter in said volume of liquid solvent increases, the material continuously traversing the chamber is continually acted on by fresh, uncontaminated solvent.

5. Apparatus for the continuous extraction treatment of organic material containing oil, fat, or resin, and for the removal 01' residual solvent from the treated material, said apparatus comprising in combination a closed treating chamber,

a closed solvent removal chamber, means for a continuously feeding the organic material into and through the treating chamber and thence continuously into, through, and out of the solvent removal chamber, means for continually heating and vaporizing in said treating chamber liquid solvent for the treatment of the material,

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