US2260730A - Refining of animal and vegetable oils - Google Patents

Description

Oct. 28, 1941. B. H. THURMAN REFIIICIA OF ANIMAL AND VEGETABLE OILS Filed Aug. 31, 1938 l lil Patented Oct. 28, 1941 Benjamin n. Thurman, nronxvme, N. y., assignor to Refining, Inc., Reno, Nev., a corporation of Nevada Application August31, 1938, Serial No. 227,826

' (or. 26o-42s) 9 Claims.

This invention relates to a process of refining animal and vegetable oils, and more particularly to a continuous process in which the free fatty acids are removed from the oils by solvents.

An object of the present invention is to provide an improved process of refining animal and vegetable oils in which a. solvent for thefree fatty acids of the oilis employed.

Another object of the invention is to provide a continuous process of refining animal and vegetable oils in which a solvent for the free fatty acids of the oil is admixed with the unrened oil and the solvent phase centrifugally separated from the oil phase.

A further object of the invention is to provide a continuous process of solvent refining animal and vegetable oils in which the process is carried on in a closed system out of contact with the air.

Ay still further object of the invention is to provide a continuous process of solvent refining vegetable oils in which high temperatures are employed for effecting a thoroughA admixture of the oil with the solvent.

Other objects and advantages of the invention Will appear in the following description of preferred embodiments thereof, given in connection with the attached drawing, which is a schematic diagram of an apparatus capable of carrying outthe process.

Referring more particularly to the drawing: III indicates a supply tank for the oil tov be refined; II indicates a closed supply tank for a fatty acid solvent; I2 indicates a proportioning mechanism for `the oil and solvent; I3 indicates a mixing'device for the oil and solvent; I4 indicates a centrifugal separator for separating the solvent phase from the oil phase, and I5 and I8 indicate respectively vapor separating chambers for separating solvent from the fatty acids and the refined oil.

In accordance with the present invention, oil to be refined is withdrawn from the tank I0 by a proportioning pump I1 forming' part of the proportioning mechanism I2 and forced through a heating device I8 shown as a coil I9 positioned in a casing 20 through which any desired heating medium may be circulated. Solvent is withdrawn vfrom tank II by a proportioning pump 2I and forced through a heating device 22 which may be similar to theheating device I8. The proportioning pumps Il and 2l may be driven by a variable speed electricmotor 23 with a speed change device 24 positioned between the pumps -to deliver the combined stream of oil `and sol,

heat exchange device 21 which oil and solvent may be withdrawn from the tanks I0 and Il. The proportioning device disclosed is shown merely way of example, and any suitable type of proportioning device capable of delivering accurately proportioned streams of oil and solvent may be substituted therefor.

The oil and solvent from the heating devices I8 and 22 respectively are delivered to a ow mixing device 25, In certain operations in-accordance with the present invention, merely bringing the oil and solvent together in ilow is suicient, but in other operations it is desirable vent to the mixer I3 indicated as a mechanical agitator, capable of thoroughly mixing substantially immiscibley liquids. Inoperations not involving the use of the mixer I3, the oil and solvent mixture can be bypassed around the mixer I3 by a pipe 26. In either case, the mixture of oil and solvent is preferably passed vthrough a may be similar to the heating device I8, for bringing the mixture to the correct temperature for separation. The mixture is then delivered to the continuous centrifugal separator I4 which is of theclosedtypel to prevent escape of solvent. The solvent phase containing the free fatty acids of the oil is discharged from the separator I4 as the lighter eiliuent through a pipe 28 and delivered into a storage tank 29-from which it may be withdrawn as a stream by means of a pump 30 and passed through a heating device 3| into the vapor separating chamber I6. 'Ihe oil,fwhich is substantially free of fatty acids and solvent, is discharged from the separator I4 as the heavy eiiluent through a pipe 32 into a storage4 tank 33, from which it may be withdrawn as a stream by means of aL pump 34 and passed through a heating device 35 into the vapor separating chamber I6. The solvent vapors are separated from the fatty acids and refined oils respectively in the vapor separating chambers I5 and I6 and delivered to a condenser 36 wherein the solvent so that any desired proportions and amounts 'of 55 is condensed to liquid form and delivered to a receiver 3l, Condensed solvent maybe returned by means of a pump 38 to the solvent tank II for re-use in the process.

If, under the temperature conditions in the evaporating chambers I5 and I6, a vacuum is necessary to substantially completelyvaporize the solvent from the fatty acids and the refined oil, a vacuum may be maintained in the condenser and evaporating system by means of a vacuum pump 39 connected to the receiver 31 through pipes 40 and 4I. In many instances a vacuumis found unnecessary, in which case the receiver 3T' may bev vented to the solvent tank II through the pipe 4I and pipe 42 lby opening the valve 43 invpipe 4I and closing the valve 44 in pipe 40. The 'storage tanks 29 and 33 are employed toA compensate for any slight variations in ow between the steps of the process, and may be relatively small in size so as to provide for substantially continuous flow of the materials through the process. These tanks maybe vented back to the solvent tank II by means of pipes 45, 46 and 42. Substantially solvent free fatty acids may be withdrawn from the vapor separating chamber I5 by means of a pump 41, and refined oil substantially free of solvent and fatty acids may be withdrawn from the vapor separating chamber I6 by means of a pump 48.

In carrying out the process of the present invention, the preferred solvent is isopropyl alcohol. Howeven'other alcohols, particularly the to approximately 20%, preferably between 5 and under pressure until lcooled prior to centrifugal separation.

Since the oil and solvent phases become less miscible as the temperature is lowered, it is desirable to cool the mixture in the heat exchange device 21 to the lowest temperature practical for the production of liquid, easily ilowable eiiluents from the centrifugal I4. This statement applies to either the relatively low temperature or the high temperature mixing step. Since the oils and fatty acids vary widely in their viscosity characteristics, depending upon the saturation 20%` water, are extremely miscible with fatty If mixing is carried on at 'relatively low tempera.

tures, for example between 70 and 120HF., it is usually necessary to ,employ a high speed mechanical agitator such as the mixer I3 in order to substantially completely dissolve the fatty acids in the solvent. The temperature of mixing necessary for complete solution of the fatty acids in the solventv will depend upon the amount of fatty acids in the oil and the amount o f solvent employed, but

will ordinarily be between`the temperatures mentioned if intense mechanical agitation is employed. The amount of solvent employed varies inversely as the amount of free fatty acids in the oil. That is to say, the greater the amount of free fatty acids. the less the amount of solvent that is required to secure a separable solventfatty acid phase. Since the amount of free fatty acids in animal and vegetable oils varies between extremely wide limits, it is impossible to give a precise percentage of solvent applicable to all oil. In general the amount of solvent employed will range between 5 and 200%, based on the weight of the oil.

vAn alternative wayl of securing an intimate mixture between the oil and solvent is to bring the temperature of mixing to a relatively high temperature, for example, approximately 200 F., at which temperature substantial portions of the oil are soluble in the alcohol solvent. 'I'hese temperatures may be obtained by either heating the oil or solvent in the heating devices I8 and 22, respectively,'or heating both the oil and solvent in these heating devices. This heating step is preferablycarried onunderl pressure to prevent vaporiz'ation of thel solvent, which pressure may be obtained by the proportioning pumps I1 and 2| and restricting the discharge from the flow mixer 25. The mechanical agitator I3 is rendered unnecessary by high temperature mixing, such that the mixture may be maintained thereof, and also the fluidityf of the fatty acid solvent phase varies with the amount of solvent employed, no precise temperature applicable to every oil can be given. In general, the best temperature for separation will vary4 from considerably below room temperature up to F., but satisfactory separation can ordinarily be accomplished in the neighborhood of 70 to 80 F.

The fatty acid phase is preferably heated in the heating device 3I to a temperature sulcient to cause.separation in vapor form of substantially all of the solvent from the fatty acids in the vapor .separating chamber I5. The solvent is relatively easily vaporized from the fatty acids and thev temperature necessary for such vaporization varies from slightly below. the boiling point of the solvent if a vacuum is employed to somewhat above the boiling point of the particular solvent employed if no vacuum is maintained in the vapor separating chamber. It is preferred to heat the mixture of solvent and fatty acids in the heating device 3l to substantially above' the boiling point of the solvent at the pressure in the heating device so that substantial vaporization of solvent is produced in the heating device. This enables sufllcient heat to be imparted to the mixture that no additional heat is necessary in the vapor separating chamber I5, although additional heat may be supplied tc the vapor separating chamber I5 by means of a suitable heating jacket (not shown). The oil from which the solvent fatty acid phase has been separated by the centrifugal separator I4, usually contains a small amount of entrained solvent. This solvent may be separated from the oil by heating in the heating device 35 and vapor separation in the vapor separating chamber I6 in substantially the same manner as separation of the solvent from the fatty acids.

It will be noted that the portions of the system in which solvent is present 'are entirely closed from the atmosphere, so that loss of solvent is substantially prevented. This is true since the fatty acids and refined oil removed from the system contain substantially no solvent. Since the alcohol will also precipitate the minor constituents such as gums and some coloring matter, these materials are also removed from the oil. Thus a refined oil is produced which is substantially free of` fatty acids and minor constituents such as phosphatidea'proteins, resins, and carbohydrates. These materials are separated with the fatty acids and may be easily removed therefrom by subsequent treating steps such as precipitating thenr from the fatty acids with 1 water, boric acid solutions or neutral slightly alkaline or slightly acid solutions of salts, which do not react with the fatty acids. This precipitated material can be settled or continuously centrifugally-separated from the fattyacids to" leave substantially pure fatty acids. Although the refined oil is substantially free of fatty acids and the minor constituents referred to, in many cases it contains considerable coloring matter which maybe subsequently removed by any of the decolorizing steps known to the art. The treatment with solvent and vaporization steps, however, will substantially deodorize the oil that is produced.

One of the chief difdculties in solvent refining of vegetable oils has been the formation of a difficulty separable emulsion between the solvent, the water contained therein and the oil, as the minor constituents of the oil are excellent emulsifying agents. -It has been found that lengthy contact between the solvent and the oil, particularly if mechanical agitation is employed, favors the formation of such emulsion. In the present process the oil and solvent may be admixed rapidly and the mixture promptly thereafter separated in order to prevent the formation of such an emulsion. Thus, the time of contact between the oil and solvent may sometimes be as short las one to twol minutes, and need never exceed ten to fifteen minutes. It will be seen that I have disclosed a continuous and rapid process of solvent refining vegetable and` animal oils in which the solvent is maintained in a closed system and is continually re-used in the process. Also, refined oil substantially free of fatty acids is `produced and high quality fatty acids are recovered'.

While I have disclosed the preferred embodiments of my invention, it is understood that the details thereof may be varied within the scope of the following claims.

I claim:

1. The process of refining vegetable oils containing free fatty acids, which comprises, mixing in a closed system a stream of said oil with a stream of a solvent which is miscible with said free fatty acids but substantially immiscible with said oil, thereby forming a concurrent stream containing a mixture of an oil phase and a solvent-fatty acid phase, continuously centrifugally separating said oil phase from said solvent-fatty acid phase, and vaporizing the solvent from said solvent-fatty acid phase for re-use in said process.

2. The continuous process of refining animal and vegetable oils containing free fatty acids, which comprises, admixing in a closed system a stream of said oil with a stream of solvent comprising a lower aliphatic alcohol containing water thereby forming a concurrent stream containing a mixture of an oil phase and a solventfatty acid phase, performing said mixing at a relatively low temperature whereby said solvent dissolves said fatty acids but does not substanf tially dissolve oil, to form an oil phase and a solvent phase and continuously centrifugally .separating said oil phase from said solvent phase to produce an oil substantially free of free fatty acids. y

3. The process of refining animal and vegetable oils containing' free fatty acids, which comprises, admixing a stream of said oil in a closed system with a lower aliphatic alcohol containing water, performing said mixing at an elevated temperature whereby said alcohol dissolves said free fatty acids and a substantial portion of said oil, cooling the resulting mixture to render said oil substantially miscible in said alcohol and form an oil phase and a solvent phase, thereafter delivering a concurrent stream containing said oil phase and said solvent phase to a continuous centrifugal separator and continuously centrifugally separating said oil phase from said solvent phase so as to produce refined voil substantially free of free fatty acids,

4. The process of refining animal and vegetable oils containing free fatty acids, which comprises, continuously mixing said oil with asolvent which dissolves said free fatty acids but does not substantially dissolve said oil to form a resulting' concurrent stream containing an oil phase and a solvent phase. delivering said stream to a centrifugal separator, and continuously centrifugally separating said oil phase from said solvent phase to produce a refined oil substantially free of free fatty acids.

5. The continuous process of refining animal and vegetable oils containing free fatty acids, which comprises, admixing a stream of said oil with a stream of solvent comprising a lower aliphatic alcohol containing water, performing said mixing at a' relatively low temperature whereby said solvent dissolves said fatty acids but does not substantially dissolve oil, to form a resulting concurrent stream containing an oil phase and a solvent phase, delivering said resulting stream to a centrifugal separator, continuously centrifugally separating said oil phase from said solvent phase to produce an oil substantially lfree ofv free fatty acids, and vaporizing said solvent from said solvent phase, condensing said solvent and admixing the same with additional oil in said process.

6. The process of refining animal and vegetable oils containing free fatty acids, which comprises, continuously mixing said oil with a solvent which dissolves said free fatty acids but does not substantially dissolve said oil to form a resulting vconcurrent stream containing an oil phase and a solvent phase, delivering said stream to a centrifugal separator, continuously centrifugally separating said oil phase from said solvent phase to produce a 'refined oil substantially free of free fatty acids, andl vaporizing said solvent from said solvent phase, condensing said solvent and admixing the same with additional oil in said process.

7. The process of refining animal and vegetable oils containing free fatty acids, which comprises,

mixing with said oil a solvent for said fatty acids which is miscible with said oil at an elevated temperature but immiscible therewith at a lower temperature', performing said mixing at said elevated temperature sov as to substantially -completely dissolve said fatty acids in said solvent, cooling the resulting mixture to form an oil phase and a solvent phase containing said fatty acids, thereafter delivering a concurrent stream containing said oil phase and said solvent phase to a continuous centrifugal separator and centrifugally separating said solvent phase from said oil phase to produce an oil substantially free from free fatty acids.

8. The process of refining animal and vegetable oils containing` free fatty acids, which comprises,

' mixing with said oil a solvent for said fatty acids which is misciblewith said oil at an elevated temperature but immiscible therewith at a lower temperature, performing said mixing at said elevated temperature so as to substantially completely dissolve said fatty acidsf'in said solvent, cooling the resulting mixture to form an oil phase and a solvent phase containing said fatty acids, thereafter delivering a concurrent stream containing said oil phase and said solvent phase to a separating zone and separating said solvent phase from said oil phase by difference in specific free fatty acids.

- 9. The process of rening animal and vegetable oils containing free fatty acids, which comprises,

concurrent stream containing an oil phase and a solvent phase, delivering said concurren stream to a separating zone and separating said oil phase from said 'solvent phase to produce a recontinuously mixing said oil with a solvent which 6 fined oil substantially free of free fatty acids.

dissolves said free fatty acids but does not substantially dissolve said oil to form a resulting BENJAMIN H. THURMAN.

Images