US2157069A - Process of refining oil - Google Patents

Description

May 2, 939. B. CLAYTON 2,157,069

PROCESS OF' REFINING O] L Filed Oct. 8, 1937 A TToR/VEVS.

Patented May 2, 1939 UNITED STATES PATENT OFFICE PROCESS F REFINING OIL Nevada Application October 8, 1937, Serial No. 168,000

19 Claims.

My invention relates to a process of refining a glyceride type oil containing impurities such as free fatty acids and other materials which are desirably removed during the refining of the oil,

for example, various color impurities, gums, etc. Cotton seed and other oils, fats and greases are examples. l

The process contemplates the refining of the oil by use of a suitable refining reagent of a type l0 capable of acting upon impurities and forming foots which are separated from the refined oil as one part of the process. Many such reagents are known to the art and can be used in carrying out the invention. The process will be described l" in detail in conjunction with an alkaline reagent although other types of reagents may be employed. Most commonly, the refining reagent is alkaline, usually being a diluted aqueous solution of an alkali such as caustic soda, caustic -o potash, etc. Such a refining reagent will neutralize the free fatty acids and form foots and Will react with other impurities. The foots produced are composed mainly of soap but may contain various other materials, and separation of these :5 foots from the refined oil will effect removal of various impurities which should not appear in th refined oil.

Sufficient-reagent is usually used to neutralize the free fatty acids with an excess to neutralize or combine with other impurities and give a proper bleach to the refined oil. The present process does not differ materially from Well known practice in this respect, and the amount of excess will be determined by preliminary tests on the oil to be refined. The strength of the solution can also be varied in accordance with knownpractice. By way of example, 5.7% by Weight of a 14 Baume solution of caustic soda can be used in refining cottonseed oil containing 1.4% free fatty acid.

Such a refining reagent, While having a preferential ainity for the impurities, also tends to react with the oil itself through a reaction forming soap and releasing glycerine. The loss in L volume of the oil during the rening process is termed the refining loss. It is made up partly of the loss due to formation of foots from the free fatty acids and other impurities, a necessary loss,

5,0 and partly of the loss due to the reaction of the reagent on the oil itself and due to entrainment of neutral oil in the separated foots, an undesirable and wasteful loss. Even small reductions in the latter loss are immensely important to the 5r, renner, and the amount of this loss is often a (ci. 26o-424) controlling factor between the failure and success of a process.

It is an object of the present invention to provide a process by which the refining loss is reduced very materially.

In rening such an oil, it is necessary that the refining reagent be intimately mixed with the oil.

I have found that the refining loss increases very fast as the temperature of the mixture is increased. For example, as between a mixture 1 maintained for a given time at 70 F. and an identical mixture maintained for the same time at 160 F., the loss will be more than four times larger in the latter instance than in the former. Also, the refining loss increases as a function of time even when the mixture is maintained at constant temperature.

It is an object of the present invention to control conditions such as temperature and time in such manner that refining losses are materially 20 reduced.

With many oils, it has now been found advantageous 'to conduct at least the first portion of the process under relatively low temperature conditions. Advantageously, the mixing is accom- 25 plished under such relatively low temperaturestemperatures commensurate with summer room temperatures so that theoil to be refined can be mixed with the rening reagent while at a temperature commensurate with summer storage temperatures. Recognizing that higher temperatures will increase the refining loss, it is desirable to use as low a temperature as will'give satisfactory rening. In the present process, it is seldom desirable to exceed a temperature of about 110 35 F. on the incoming oil, though this is not a limiting temperature and can be exceeded considerably, particularly if other features of the invention hereinafter described are used. Most oils can be processed satisfactorily at lower tempera- 40 tures, for example, from about 70 F. to 100 F., and many oils Will respond favorably if mixed with the refining reagent at temperatures in the general neighborhood of 85 F.

It is an object of the invention to provide a process in which, if desired, relatively low mixing temperatures can be used.

Another object of the invention is to make possible the maintenance of such relatively low temperatures throughout most or all of that portion of the process preceding the step of separating the refined oil from the foots.

Centrifugal separation has been found desirable and, in many instances, the mixing temperature can be maintained up to a. point adjacent the zone of centrifugal'separation. At such a. point, many advantages accrue from subjection to an abrupt elevation in temperature. Separation is facilitated, free and continuous movement of the foots from the bowl insured, breaking of emulsions effected, and many other advantages derived from this expedient as will be described in detail hereinafter. y

It is another object of the invention to subject the mixture to an abruptly elevated temperature adjacent the zone of centrifugal separation.

This can be accomplished in various ways, the most satisfactory of which is to apply heat to the exterior of the rotating bowl, and it is an object of the invention to so heat the bowl by various means, for example, by introducing steam around the bowl or otherwise heating the bowl directly or by heat transfer. By such an expedient, it is possible to heat diiferentially the oil and foots while at the same time overcoming the refrigerating effect of the centrifuge and causing the foots to slip uniformly upward along the inner wall of the bowl to scour and maintain. this inner wall substantially free from accumulations which would otherwise cause non-uniform discharge of the foots with attendant surging and shifting of the neutral zone, and which would cause accumulation of such deposits as would require shut-down every few hours to clean the bowl.

It is an object of the preferred embodiment of the invention to discharge the oil and foots from the zone of centrifugal separation at different temperatures. For example, the foots may be discharged at temperatures many degrees higher than the oil. Thus, it is possible in the present invention to maintain the oil at relatively low temperatures throughout the process with many attendant advantages while discharging the foots in a heated condition to insure continuity of the process for long periods of time and better seperation of the refined oil and foots.

On the other hand, if the heat applied adjacent the zone of centrifugal separation is applied in a manner to heat the oil as well as the foots, the heating should be quite abrupt and the foots immediately separated if refining losses are to be at a minimum, for the oil will then be subjected to higher temperatures for a relatively short period of time.

In the present invention, the time interval between removal from the mixing zone and introduction into the zone of centrifugal separation canbe very short. A short conduit is best in this capacity and can be so designed with reference to iiow conditions that the foots will be maintained unifomly dispersed in the oil, thus overcoming any tendency to-ward premature separation of the foots such as would discharge excessive amounts of foots into the centrifuge at intervals to negative the desirable results accruing from delivering a uniform mixture to the centrifuge. In some cases, mixing can even take place in the entrance portion of the centrifuge, for example, by jetting separate streams of oil and reagent into the centrifugal inlet.

Irrespective of whether heat is applied adjacent the zone of centrifugal separation, though desirably in conjunction with this feature, it is an object of the invention to mix oil and rening reagent intimately and conduct the mixture from the mixing zone to a centrifugal separating zone without undue delay and preferably directly and immediately and while maintaining the uniaruosa formlty of the mixture to' prevent premature sepf aration of the foots.

'I'he time during which the materials are in the mixing zone is short so that the total time interval between the bringing together of the oil and refining reagent and the subjection to centrifugal force need be only a little longer than the time of mixing itself. Even this mixing time can be shortened, if desired, to a matter of seconds, so as to perform the operation in a short period of time with consequently decreased refining losses. In fact, by bringing flowing streams of oil and reagent properly together, the mixture will form practically instantaneously and the free fatty acids will be immediately neutralized.

It is an object of the invention to shorten the time necessary to refine an oil, thereby reducing the refining losses.

Further objects of the invention lie in the provision of a novel apparatus for refining oils. These and other objects will be made evident from the following description exemplifying ways in which the refining steps can be performed.

The attached drawing is a schematic diagram illustrating one type of apparatus which has been found very advantageous in refining many types of glyceride type oils.

Referring thereto, the glyceride type oil to be refined may be Withdrawn from suitable storage and introduced into a tank II. If desired, suitable means, such as a coil I2, may be employed to heat or cool the oil to the desired starting temperature. Similarly, a tank I3 may contain the refining reagent, prepared therein or introduced thereinto from another source. The temperature of this rening reagent can be regulated by a coil I4 through which a heating or cooling medium may be circulated to bring the refining l reagent to a desirable starting temperature.

Separate streams of the oil and refining reagent are withdrawn from the tanks II and I3 and delivered to a suitable mixer I8. Various types of proportioning pumps may be used in this capacity. As diagrammatically shown, the oil is withdrawn from the tank II through a pipe I9 and introduced into the mixer I8 by means of a pump 20 and a pipe 2|. Similarly, the refining reagent is withdrawn from the tank I3 through a pipe 22 and delivered to the mixer I8 by a pump 23 and a pipe 24. The pumps 20 and 23 are interconnected by a variable-speed connection 25 for controlling the relative pumping action and thus controlling the proportions of oil and refining reagent delivered to the mixer I8. Both pumps may be driven from a single prime mover indicated as a motor 26.

Various types of mixers I8 can be used without departing from the spirit of the invention. The mixing action can be obtained by injection, turbulence, mechanical agitation, or by other means. I have found it eminently satisfactory in securing an intimate mixture to introduce one of the materials into a owing stream of the other. As before indicated, it is possible, in some instances, to perform this operation in the centrifuge inlet. Preferably, the refining reagent is introduced into a flowing stream of the oil in a zone closed from the atmosphere, the pressure developed by the pumps being sucient to deliver the resulting mixture to the separating zone. By Wayof example, the mixer I8 mayinclude a chamber receiving both streams and maybe so designed that intimate mixture is obtained by injection or turbulence, or both. All that is required is that the streams be brought together and mixed to distribute the refining reagent uniformly in the oil. Neutralization of the free fatty acids is practically instantaneous, and the resulting mixture will contain foots uniformly dispersed in the stream leaving the mixer I8 through a pipe or conduit 21.

The mixing time can be relatively short, a matter of seconds, if desired, or it may be prolonged to give additional time for the continuance of various reactions other than the neutralization of the free fatty acids. This neutralization is practically instantaneous once the mixture is formed, and the foots resulting from this neutralizing reaction will appear immediately in the mixture. However, with some oils, the excess refining reagent will act more slowly upon other impurities, for example, upon the coloring matter. Such supplementary reactions may be allowed to continue to a greater extent by increasing the time that the materials are in the mixing zone. These supplementary reactions need not be complete before the mixture is discharged from the mixer I8, for the subsequent steps of the process can be made to facilitate such reactions. However, in the illustrated embodiment, it is very desirable that all of the free fatty acids be neutralized before the mixture is discharged from the mixing zone.

The resulting mixture, if mixed in a zone externally of the centrifuge, is conducted to a separating means, shown as a centrifuge 30, by the conduit 21. During this transportation of the mixture, it is preferably maintained in such condition that the foots will not prematurely separate. Sufficient mild turbulence in the conduit 21 can be maintained by proper design thereof, with the end in View of maintaining the foots uniformly dispersed in the oil. This insures delivery to the centrifuge 30 of a mixture which is uniform from time to time in the relative amounts of refined. oil and foots therein.

In the preferred embodiment of the invention, the conduit 21 is relatively short so as to conduct the mixture directly and immediately to the centrifuge 3D. Preferably also, the temperature of the mixture is maintained during this transportation to the centrifuge, with no heat added or removed from the mixture in any substantial degree.

On the other hand, many advantages accrue from the subjection of the mixture to an abruptly elevated temperature adjacent the zone of centrifugal separation. This may be accomplished in various ways. Heat may be applied to the mixture at a point immediately ahead of the centrifuge 30, as by injecting a heating medium, for example, hot water or superheated steam, into the conduit 21 at a point ahead of this centrifuge, or the heating medium may be delivered directly into the centrifuge inlet. Preferably, however, subjection to this abruptly elevated temperature is accomplished by applying heat externally of a rotating bowl 3l of the centrifuge, this bowl being journalled in suitable bearing means including a bearing 32 diagrammatically shown. Heat can be applied to the external wall of the bowl either directly or by heat exchange means. For example, steam or other heating medium can beintroduced through a pipe 34 into an annular space 35 between the bowl and a housing 36 of the centrifuge 3U. Alternatively, the heating medium may be circulated through a coil 31 disposed in this annular space 35, or heat may be otherwise applied to the bowl 3 I.

The internal construction of the centrifuge bowl is well known in the art and is not shown in detail in the annexed drawing. Suffice it to say that the mixture of refined oil and foots is continuously discharged into the rotating bowl 3l where centrifugal force isV effective in moving the foots outward to a zone adjacent the inner wall of the bowl. Heat applied externally of the bowl will selectively heat this layer of foots and insure continuous upward movement thereof until the foots discharge into a heavier-effluent pan 39 provided with one or more spouts 40 through which the separated foots are discharged. The refined oil seeks an inner zone in the rotating bowl 3| and moves upward through passage means not shown to be discharged into a lighter-efliuent pan 43 and thence through a spout 44 thereof to storage or to subsequent treating equipmentfor example, washing and drying, or bleaching apparatus.

External heating of such a rotating bowl permits discharge of the foots and oil at different temperatures. For example, the temperature of the foots may be many degrees higher than the temperature of the discharged refined oil. In many instances, I nnd it desirable to maintain the oil at relatively low temperature throughout the process, applying heat mainly to the exterior surface of the rotating bowl to facilitate separation and discharge the foots at a considerably higher temperature. Such heating of the bowl 3| overcomes the normal refrigerating effect of a centrifuge. It prevents adherence of various constituents of the foots, such as gums, to the bowl itself and thus prevents building up of a layer of material thereon which may periodically release and be suddenly discharged to set up surges in the zone of centrifugal separation which will cause displacement of the neutral zone therein. Even if such accumulations did not periodically release, building up thereof would inevitably shift the neutral zone and prevent the clean separation made possible by externally heating the bowl. This expedient insures uniform and continuous movement of the foots along the surface of the bowl to establish a scouring effect. It results in other advantages hereinbefore mentioned and permits continuous operation of the centrifuge for long periods of time, eliminating the frequent shut-downs heretofore found necessary if no heat was applied to the bowl.

Another very important advantage of subjection to abruptly elevated temperatures is that the emulsion which usually forms when oil andLreflning reagent are mixed at relatively low temperature will be broken. If not broken, such an emulsion will prevent effective separation of the oiland foots. By applying heat to the exterior of the bowl 3i, this emulsion is broken into its constituents, the refined oil otherwise therein being released to disc-barge with the main stream of refined oil and the soap, water, and traces of other undesirable substances being discharged as foots. There results a distinct lowering of the refining loss and-the production of a better refined oil. l

Many of the above advantages can also be obtained by abruptly heating the mixture immediately ahead of the centrifuge or in the centrifuge by direct contact with a heating medium. For example, if steam or hot water is introduced thereinto, the resulting increased aqueous content will separate with the foots. In this instance, a large differential heating of the refined oil and foots will not be obtained. However, the refined oil will be subjected to the higher temperature for only a very short period of time with resulting decrease of refining losses.

'I'he various features of the invention individually discussed hereinbefore can be used separately or combined. A combined use is indicated in the following illustrative example without intention of limiting the invention thereto.

Cottonseed oil already existing at summer storage temperatures can be introduced into the tank Il, no additional heat being added through the coil t2. The refining reagent may be at a somewhat different temperature but, dlesirably, is maintained at commensurate temperatures in the tank I3. An aqueous solution of caustic soda of a strength usually used with this oil and used in well known excesses will be found very satisfactory.

By use of the mixer I8 and the pumps, the streams can be brought together and mixed for a relatively short period of time, and the mixture moved directly and immediately through the conduit 21 which may be quite short. The summer temperatures can be maintained until the mixture enters the centrifuge 30. Adjacent the zone of centrifugal separation, the constituents of the mixture are subjected to an abruptly elevated temperature, preferably by heat applied to the exterior of the bowl, so that heat is carried to the zone of centrifugal separation. The foots may thus discharge at a temperature materially above the summer temperature of the incoming oil. The discharged refined oil will often be found to remain substantially at its original summer temperature though, in some instances, it will be raised to a slightly higher temperature.

Another combined use of certain of the features mentioned above, without reference to the mixing at summer temperatures, is particularly valuable with many oils. Thus, it is desirable to conduct the mixture from the mixing zone directly and immediately to the zone of centrifugal separation, preferably by use of a conduit 21 which maintains the mixture out of contact with the atmosphere, and to subject the mixture to an abrupt elevation in temperature adjacent the centrifuge. This mode of procedure is particularly valuable if the heat is applied to the exterior of the rotating bowl, and will distinctly reduce the refining losses. At the same time, it will facilitate continuous separation over long periods of time, break the emulsion, and produce the other advantages mentioned above with respect to the use of such a centrifuge.

While the invention has been particularly described with respect to refining of glyceride oils with alkaline reagents, other reagents can be employed. Many glyceride oils, particularly drying oils, are refined with acids, for example, relatively concentrated sulphuric acid, which do not neutralize free fatty acids but do react with and render separable as foots other impurities such as gums and coloring matter. Also, the gums may be rendered separable as foots by employing water or very dilute solutions of acids,

salts or alkali as the refining reagent and, in many cases, I have found that a considerable amount of foots made up primarily of gums may be centrifugally separated without the addition of any reagent. Such partial refining processes are ineluded under the general term refining as employed in this application.

In.' any of these refining operations, I have found that it is the gums which tend to adhere to the walls of the centrifugal bowl and build up a layer thereon so as to interfere with separation and cause surging. The application of heat to the centrifuge largely avoids this dlfilculty such that the foots are continuously discharged therefrom and the centrifuge can be maintained in operation indefinitely without cleaning. Also, in any type oi refining and particularly operations employing strong alkali and acid solutions, the reagents attack the oil itself and this effect is greater the higher the temperature and the longer the time of contact between the oil and reagent. It is, therefore, desirable to keep the time of contact as short as practicable. In general, heat facilitates the centrifugal separation' of the foots from the oil in any of the types of refining above-discussed by reducing the viscosity of the oil and foots and aiding in breaking or preventing the persistence of any emulsion present or which tends to form.

. Thus. temperatures between F. and 160 F.

are usually found advantageous during separation. In many cases, however, it is possible to employ somewhat lower temperatures and, in some casesl even higher temperatures can be employed although care must be taken that temperatures which cause the formation of substantial amounts of vapors and resultant priming in the centrifuge are not reached. The temperature employed in any operation will depend upon the type of oil being refined and also the type of reiining and an optimum temperature for such op- 1 eration can be readily determined. It is desirable to employ the lowest temperature which will produce effective separation in order to minimize refining losses.

Various changes can be made without departtrifugal separation and continuously separating the foots from the oil.

2. A process of refining glyceride type oils which contain impurities by use of a refining reagent capable of acting upon the impurities to form foots, which process includes the steps of: bringing together and mixing proportioned streams of said oil and said refining reagent in a zone confined from the atmosphere to produce a mixture containing oil and foots; continuously removing a stream of said mixture from said Zone and conducting same directly and immediately to a separating zone while maintaining said foots uniformly dispersed in said oil during conveyance to said separating zone; subjecting said mixture to centrifugal action in said separating zone and to an abrupt elevation in temperature adjacent said separating zone to separate said mixture into rened oil and foots; and continuously removing said refined oil and foots from said separating zone.

3. A process of refining glyceride type oils which contain impurities by use of a refining reagent capable of acting upon the impurities to form foots, which process includes the steps of: bringling together and mixing proportioned streams of said oil and said refining reagent in a zone confined from the atmosphere to produce a mixture containing oil and foots; continuously removing a stream of said mixture from said-zone and conducting same to a separating zone while maintaining said foots uniformly dispersed in said oil during conveyance and while maintaining the temperature of said mixture substantially the same as when formed; rotating said mixture in said separating zone while applying heat adjacent the zone of separation to subject said mixture to an abruptly elevated temperature thereby centrifugally separating the foots from the oil; and continuously removing said refined oil and foots from said separating zone.

4. A process of refining glyceride type oils which contain impurities by use of a refining reagent capable of acting upon the impurities to form foots,l which process includes the steps of: bringing together and mixing proportioned streams of said oil and said refining reagent in a passage confined from the atmosphere to produce a mixture containing oil and foots; continuously moving the mixture as a stream along said passage and into a separating bowl While maintaining said foots uniformly dispersed in said oil during conveyance; rotating said bowl to displace said foots to an outer position therein; applying heat to said bowl; and continuously removing said reiined oil and foots from said rotating bowl.

5. A process of refining glyceride type oils whichcontain impurities by use of a refining reagent capable of acting upon the impurities to form foots, which process includes the steps of: bringing together and mixing proportioned streams of said oil and said refining reagent in a zone confined from the atmosphere to produce a mixture containing oil and foots; continuously removing a stream of said mixture from said zone and conducting same to a separating bowl while maintaining said foots uniformly dispersed in said oil during conveyance; rotating said bowl to displace said foots to an outer position therein; heating said rotating bowl externally to produce a difference in temperature between said foots and the refined oil separating therefrom; and continuously removing said refined oil and foots from said rotating bowl.

6. A process of continuously refining oils of the glyceride type containing impurities by use of a refining reagent capable of acting upon the impurities to form foots, which process includes the steps of: pumping into a zone closed from the atmosphere a stream of said glyceride type oil; pumping into said zone a stream of said rening reagent an-d forming an intimate mixture of the oil and reiining reagent during continuous advancement along said Zone; continuing the forward advancement to move said mixture directly and immediately to a separating zone while under the iniiuence of pressure derived from the introduction of said oil and refining reagent into said first-named zone; centrifugavlly separating the foots from the refined oil in said separating zone while subjecting the mixture to an abrupt elevation -in temperature adjacent said separating zone; and continuously and separately removing said foots and refined oil from said separating zone.

7. A process of refining oils of the glyceride type containing impurities, which process includes the steps of continuously bringing together and mixing proportioned streams of said oil and a refining reagent capable of acting upon the impurities to form foots; continuously conducting the resulting mixture of oil and foots to a zone of centrifugal separation through a relatively short conduit closed from the atmosphere; and abruptly subjecting said mixture to an .increase in temperature at the zone of centrifugal sepa'- ration to facilitate centrifugal separation and continuously separate the foots from the refined oil.

8. A continuous process for refining glyceride type oils which contain impurities by use of a refining reagent capable of acting upon the impurities to form foots, and producing separate continuous discharges of refined oil and foots,

with the foots at a higher temperature than the discharged refined oil and while avoiding the application to the oil of such high temperatures as would markedly increase the refining loss, which process includes the steps of mixing proportioned streams of said glyceride type oil and said refining reagent while maintaining said oil at a relatively low temperature comparable to summer temperatures; conducting the resulting mixture as a stream to a zone of centrifugal separation as fast as said mixture is formed While maintaining said relatively low temperature during conveyance whereby said foots are moved outward from the oil in said zone of centrifugal separation to form an outer layer of foots; applying heat to said outer layer of foots to heat same above the temperature of the separated oil while avoiding such heating as would largely increase the temperature of the separated oil over and above said relatively low temperature; and continuously withdrawing the separated oil and foots from said zone of centrifugal separation.

9. A process as defined in claim 1 in which said oil is at summer temperature when mixed with said refining reagent.

10. A continuous process of refining glyceride type oils which contain impurities such as free lli fatty acids by use of a refining reagent capable K of reacting with said impurities to form foots, which process includes the steps of: continuously mixing in a mixing zone closed from the atmosphere proportioned streams of said oil andreiining reagent used in excess of that amount theoretically required to neutralize said free fatty acids; maintaining said mixtui at relatively low temperature while undergoing neutralization; continuously removing a stream of the resulting mixture of oil and foots from said mixing zone and conducting same toward a zone of centrifugal separation while maintaining same at said relatively low temperature and while maintaining said foots uniformly dispersed in the oil; and separating the foots from the refined oil in said mixture by centrifugal force while abruptly subjecting same to an increase in temperature thereby assisting separation and minimizing refining losses.

11. A continuous process ofv refining glyceride type oils which contain impurities such as free fatty acids by use of a refining reagent capable of reacting with said impurities to form foots, which process includes the steps of continuously mixing in a mixing zone closed from the atmosphere proportioned streams of said oil and refining reagent used in excess of that amount theoretically required to neutralize said free fatty acids; maintaining said mixture at relatively low temperature while undergoing neutralization; continuously removing a stream of the resulting mixture of oil and foots from said mixing zone and conducting same toward a zone of centrifugal separation while maintaining same at said relatively low temperature and while maintaining said foots uniformly dispersed in the oil; subjecting the mixture to the action of centrifugal force in a rotating bowl to throw the foots outward in said bowl; and applying heat to the exterior of said bowl to assist continuous discharge of the foots from the bowl and produce foots which discharge from the bowl at a higher temperature than the rened oil.

12. A process of continuously refining oils of the glyceride type containing impurities such as free fatty acids, by use of a refining reagent capable of reacting with said free fatty acids to form foots, which process includes the steps of: continuously mixing proportioned quantities of a glyceride type oil and a refining reagent used inV excess of that amount theoretically required to react with said free fatty acids; immediately subjecting the resulting mixture of oil and foots to a centrifugal separating action while maintaining the temperature of the resulting mixture substantially constant until it reaches a position adjacent the zone of centrifugal separation; quickly applying heat to said mixture at said position adjacent the zone of centrifugal separation; and separately and continuously removing the foots and refined oil from said zone of centrifugal separation.

13. A process for the quick and continuous refining of animal and vegetable oils containing free fatty acids, which comprises the steps of: mixing with said oil a refining reagent capable of acting upon impurities in said oil to form foots, separating the foots substantially as quickly as it is formed by subjecting the mixture to immediate centrifugal separation with the aid of sufficient heat to facilitate said separation, the process being characterized by the avoidance of any substantial period of contact of the refining reagent with the oil after the admixing thereof.

14. The process as defined in claim 13 in which the oil and reiining reagent are adxnixed Within the centrifugal momentarily before centrifugal separation.

15. The process as defined in claim 13 in which the time of contact of thereflning reagent and the oil is not substantially greater than the time required for centrifugal sepaartion.

16. The process as defined in claim 13 in which properly proportioned streams of the oil and reagent are contacted substantially as they enter the centrifugal. v

17. A process for the substantially simultaneous forming and separation of foots from rened oils, which comprises the steps of: colliding streams of a refining reagent capable of acting upon impurities in the oil to form foots arid the oils, under super-atmospheric pressure, to effect substantially instantaneous formation of said foots and immediately separating said foots substantially as quickly as the same are formed by immediately subjecting the mixture to centrifugal separation for continuously separating the said foots from the oil, the process thereby being characterized by the avoidance of any substantial period of contact of the refining reagent with the oil after the admixing thereof,

18. The process as defined in claim 17 in which the refining reagent is acid.

19. A process for the quick and continuous rening of animal and vegetable oils, which comprises, the steps of mixing with said oil a refining reagent capable of combining with impurities in said oil to form an emulsion containing foots, and breaking said emulsion substantially as quickly as it is formed by delivering the same to a centrifugal separator and applying heat to the external Walls of the bowl of the centrifugal separator during the act of centrifugally separating the foots from the puried oil to subject the emulsion to an emulsion-breaking temperature and also to prevent sticking of the foots to the walls of the centrifugal separator bowl, the process being characterized by the avoidance of any substantial period of contact of the rening reagent and the oil after the admixing thereof.

BENJAMIN CLAYTON.

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