US2337041A - Refining of cottonseed oil - Google Patents

Description

3- l. K. GILES ET AL 2,337,041

REFINING OF COTTONSEED OIL Filed April 8, 19:58

Salvent Sluajg 29 51 Filter fracfzvmztin Column i 64 63 32 7] Separator 50 6'2 Separator Water Clary Steam 66 Oil Solvent 43 7 3 3;- Jolvent fhztionatiqg Column .1 50 55 47 44 k 4.5 Sepamvr INVENTORS Soap Clear Ozl Megzd 602 2611 BY Irpu; l1". Gzles and Wzllzamifellgy Patented Dec. 21, 1943 REFINING F co'r'rousnnn on,

Irvin K. Giles, Cranford, N. 3., Mead Cornell,

, Cleveland, Ohio,

and William Kelley,

Los

Angeles, Calif.; Lena F. Giles, administratrix of said Irvin K. Giles, deceased; said administratrix and said Kelley assignors, by direct and mesne assignments, to The Lummus Company, a corporation of Delaware Application April 8, 1938, Serial No. 200,928

16 Claims.

This invention relates to improvements in refining animal and vegetable oils, more particularly crude cottonseed oil.

Refining of crude oils of animal and vegetable origin by continuous methods has heretofore been proposed, but it has been found thatthe continuous treatment as practiced is costly as it can only be accomplished by the use of special apparatus and under the objectionable operating conditions of a minimum time cycle. This requires uneconomical quantities of reaction products and if the rapidity of reaction and separation is'not maintained, inferior products resuit. The time factor is thus a critical operating condition.

One of the principal objects of the present invention is to provide an improved method for the refining of animal and vegetable oils, particularly cottonseed, soya bean and other glyceride oils, in which high production can be accomplished by a continuous fiow of oil which is attenuated'but not subdivided, in the presence of the treating materials in the respective treatment steps so that the amount of treating materials may be materially reduced.

A more specific object of the invention is to provide an improved manner of neutralizing the free fatty acids for removal thereof which comprises simultaneously mixing the oil body and neutralizing agent and immediately attenuating the mixture without subdivision or emulsification so that the soap will freely separate from the oil without critical time or temperature conditions.

Another object of the invention is to provide an improved method of refining vegetable and animal oils by which the end products are of a more highly refined quality, have a total value in excess of that of the end products heretofore produced, and in which the relatively low concentrations of oil carried by the treating materials can be recovered.

Further objects and advantages of the invention will appear from the following disclosure of a preferred form of embodiment of our invention taken in connection with the attached drawing which is a diagrammatic flow arrangement for the treatment of oils.

Oils of animal and vegetable originj'such as cottonseed oil, are commonly refined to be r'en-.

dered edible, and deleterious matter, as well as free fatty acids, must be removed for this purpose. Such oils as prime crude oils may have impurities of approximately 1, such impurities being of a gummy or mucilaginous type, and

a free fatty acid content in the range ofl f or more. In addition, there is usually a substantial amount of objectionable coloring matter. The removal of these elements, without excessive shrinkage, which now ranges from 5 to 9%, and without excessive use of time or ma- 4 terials', is essential for commercial acceptance. While the invention is not limited to any particular oil, and to no specific limit of impurities, the invention will be foundespecially applicable to the refining of such a product.

oil, which is carried by pipe l0 into tank H,

with a suitable washing liquid such as water entering at H. Only a small proportion of wash water or liquid is required and with approximately 1% of impurities, the amount of water is approximately 5% of the incoming oil. The oil and wash liquid are slowly and gently stirred by the paddle l3 and, if desired, the entire mixture may be heated by suitable heating coils M to a temperature of approximately F. The mixture of water and oil is then continuously pumped through pipe l5 by pump 15a (or carried by gravity it convenient) to a separating device such as settling tank IS in which the oil separates from the gums and meal content which are mixed with the water. This sludge is pref-- erably drawn on from the bottom, as at IT, and contains approximately all of the added water and all of the gummy resinous materials. This accounts for an unavoidable shrinkage of about 1% of the original feed. I

As the second step in the process, the oil is preferably decolorized with clay or suitable adsorbent and substantial advantage is obtained, in using a material such as Filtrol whichis'an acid treated, porous, silica of good decolorizing quality. The water washed oil is discharged in measured quantities, as for example, by a proportionating device l8, such as described in Corespecially satisfactory for this purpose is de-' scribed in Cornell U. S. Patent No. 2,042,880.

The flow of mixed oil and clay in such a device 'ditions.

is normally through the inlet housing 23 over the rotor 24, under the spreader 25, and it is then deflected downward by the shell so that a continuous thin film is maintained. The clay may be mixed at an elevated temperature if desired,

and we find a temperature in the neighborhood of 140 F. to be desirable. The contacting is also preferably carried out under a substantial vacuum in. the range of 26" of mercury obtained by vacuum pump 26, which assures an elimination of air and thus prevents oxidation. It is believed that operation under a suitable pressure of inert gas would also be effective.

The mixture of clay and oil which'collects in the bottom of attenuating device 24 is then continuously removed by pump .28 and-discharged which the filtrate is drawn off at 3| and the filter cake is removed at 32. The filtrate is a decolorified, gum. free oil of a light pale color and is ready for the removal of the free fatty acids. 'It is found to be superior in'color to the oils otherfree of excess water, and it contains only a small through line 29 into the continuous filter 30. This filter is of any desired commercial type from amount (1% or less) of oil which can be recovered as hereinafter described. No saponification of the neutral oil occurs during the period 'of attenuation, and the alkali acts as a selective neutralizing agent only on the acid content of the oil. There appears to be no need of added heat, except to improve the viscosity of the wise decolorized and the color adsorbing material is used in smaller quantities for the amount of coloring matter removed than under other con- This is due, to a substantial degree, to the finely attenuated stream which may be of a thinness of approximately .005", which assures a most intimate contact with the adsorbent.

The removal of the free fatty acids is accom- I plishedby reaction with a suitable neutralizing agent and many are known, especially alkali such In accordance with this; proc-1.

as caustic soda. ass, a substantially complete removal of the free fatty acids can be accomplished without an exproduct, and operations can be effectively car ried out at normal room temperatures.

The soap stock which is removed from the bottom of separator 42, although substantially oil free, can be improved andthe oil removed. A preferable arrangement is to introduce proportioned amounts of soap stock and a soap solvent such as alcohol and water through proportionating devices 44 and 45, and then'attenuate the stream as by attenuating device 46, which is of a type similar to the prior devices 2| and 36, but

substantially smaller in view of the much lower I volume of materials handled. The intimate mixcess of alkali, and therefore without saponifying the neutral 011. While we do not wish to be limited to any precise'theory of operation, it appears to be possible to accomplish this step of the process by virtue of having first degummed and decoloriied the oil, and then obtaining an effective film contact between the oil and alkali by attenuating the oil stream without subdividmg the oil. This not only assures the desired neutralization, but avoids the formationof an emulsion, thereby facilitating the later separa tion of the oil from the soap. i

The oil and alkali are mixed in precisely proportioned amounts as by proportionatingdevices Neutralization of the free fatty acids occurs dur-' ing theperiod that the oil filmis attenuated to and complete neutralization occurs with the theo retically required amount of alkali. Thisis undoubtedly facilitated by the; absence of all del eterious matter. If. it is found desirable, a slight" excess (5%) of alkali may be used. Accurate control of the time of contact and-of the film f thickness is hadv by variation of therate of feed and the rotor speed. I a Y H The oil and soap in suspension are then drawn from attenuating device 35 by pump and discharged through pipe '4! to a separating device42 a which may suitably be a settling tank. The free soparationof the soap from the oil is a. marked feature of the invention as it can be accom plished in a comparatively short time, merely ture of soap solution and oil is then separated as in any'preferred form of separator such as the settling tank 41 into which the mixture is pumped by pump 48 in line 49. A vacuum is conveniently maintained onattenuating device 46 as by vacuum pump 50, and this prevents the formation of an emulsion. The clear oil which is drawn off at 52 represents approximately 1% of the original charge.

The soap and alcohol solution removed at 53 is pumped by pump 54 into fractionating column 55, which is operated under suitable conditions to remove the alcohol and water as soap solvent overhead at 56 andwith the soap removed at 51 from the bottom. This soap is of especially high grade, being of superior color and free of oil, and it also commands a premium in the trade. Being free of oils, it is only approximately 3% or less of the initial charge of crude oil. This represents a definite shrinkage in the amount of refined oil,

but is very muchlower than ordinary.

Recovery of additional oil from the filter cake removed at .32 from filter 30 is also economically possible. This cake contains approximately 30% of oil (representing about 1% of the original charge), the clay and the adsorbed coloring matter removed in the filter. The clay is discharged through a form of spiral or other conveyor 60 in the presence of an oilsolvent added at 6| to separator 62 which is conveniently a settling tank.

' The oil and solvent are removed from the separator through pipe 63 and discharged into fractionating column 64 in which the solvent'which was used to free the oil from the clay is vaporized and removed overhead at 65. The oil is recovered at 65. If the solvent used also removes all of the entrained coloring matter from the clay, the oil will be of a very dark color and when sufiicient has been accumulated, it may be run as a batch through the first attenuatin device .2l b running it through proportionating device i8 and manifoldlS. Approximately 1% additional yield may obtained in this manner.

1 The clay from separator 62 is conveniently discharged intoanother conveyor 68 in the presence of steam or other vapor introduced at 69 to complete the removal-of solvent. The .cleanclay is removed at and the vapors conducted at H into the column 6 1. If necessary, a settling tank 12 may be used'to separate out water .as steam condensate, and this is drawn off at 13.

It is, ofcourse, possible to add different solvents at El to remove the oil'as a clear product, thus leaving, the coloring matter in the clay for further treatment. In such case, the clear bleached oil recovered at 66 is approximately 1% of the oil recovered at 43 and 52. Clay revivification, if desired, would becarried out as a. separate treatment in accordance with any desired plan.

During the entire process, the oil stream is never subdivided or broken up, but is maintained as a continuous body, and only attenuated during the treating steps so that the treating materials are active. This results in reactions which cannot be accomplished in any length of time of mixing in other machines and appears to explain 'the very rapid separation of the oil and soap after neutralization. Furthermore, the end products are clearly superior to the best possible under present commercial practices, and we not only use less clay and alkali, but reduce our shrinkage of which the principal part is an improved soap.

The separation of oil and other products in the various steps, although described as being effectively accomplished by settling, can also be accomplished by mechanical separation such as in a centrifuge, if desired. A preferred form of embodiment of the invention has been shown and it is well known that modifications may be made thereto without departing from the inven tion. A broad interpretation of the invention within the scope and spirit of the description herein and of the claims appendedhereinafter is thus desired.

We claim: I v V 1. An improved method for neutralizing the free fatty acids in animal and vegetable oils without any substantial saponification of the oil which comprises the steps of conducting separate streams of oil and a caustic neutralizing agent to a rotary disk mixing device, combining the separate materials on said disk. rotating said disk at a relatively high peripheral speed to cause said materials to flow across said disk in a thin film under substantial centrifugal force whereby immediate neutralization of the fatty acids is accomplished, removing the mixture of oil and neutralized acid in a continuous film into a liquid receiving zone without forming an emulsion of the oil, the amountof caustic neutralizing agent being slightly in excess of the amounttheoretically required to neutralize the acid, thetime of contact of neutralizing agent with the'charge oil, the uniform dispersion of neutralizing agent with respect to the dispersion of the acid in the oil film and the amount of neutralizing agent being such that the acid is neutralized in preference to any reaction of the neutralizing agent with the oil.

2. An improved method for neutralizing the free fatty acids in animal and vegetable oils without any substantial saponification of the oil which'comprises the steps of conducting separate streams of oil and a caustic neutralizing agent to a rotary disk mixing device, combining the separate materials on said disk, rotatin said disk at a relatively high peripheral speed to cause said materials to flow across said disk in a thin film under substantial centrifugal force whereby immediate neutralization of the fatty acids is accomplished, removing the mixture of oil and neutralized acidin a continuous film into a liquid receiving zone without forming an emulsion of the oil, the amount of caustic neutralizing agent being slightly in, excess of the amount theoretically required to. neutralize the acid, the time of contact of neutralizing agent with the charge oil, the uniform dispersion of neutralizing agent with respect to the dispersion of the acid in the oil film and the amount of neutralizing agent being such that the acid i neutralized in preference to anyreaction of the neutralizing agent with the oil, said neutralization being carried out at a substantially uniform temperature and under a subatmospheric pressure.

3. An improved method for refining animal and vegetable oils withoutsubstantial saponification of the oil which comprises the steps of mixing the oil with a small proportion of water to establish a hydration of the resinous matter therein, separating such hydrated resinou matter from the oil, conducting said oil to a rotary disk mixing device, separately conducting a stream of caustic neutralizing agent to said disk, combining the oil and neutralizing agent on said disk, rotating said disk at a relatively high pcripheral speed to cause said materials to flow across said disk in a thin film under substantial centrifugal force whereby immediate neutralization of the fatty acids is accomplished, removing the mixture of oil and neutralized acid in a continuous film into a liquid receiving zone with out forming an emulsionof the oil, the amount of caustic neutralizing agent being slightly in excess of the amount theoretically required to neutralize the acid, the time ofcontact of neutralizing agent with the charge oil, the uniform dispersion of neutralizing agent with respect to the dispersion of the acid in the oil film and the amount of neutralizing agent being such that the acid is neutralized in preference to any reaction of the neutralizing agent with the oil. I

4. An improved method for refining animal and vegetable oils without substantial saponification of the oil which comprises the steps of mixing the oil with a small proportion of Water to, establish a hydration of the resinous matter therein, separating such hydrated resinous matter from the oil, conducting said oil with a proportionated amount of a decolorizing material to a rotarydisk mixing device, rotating said disk to cause said materials-to flow thereacross in a thin film to obtain intimate admixture of the decolorizing material withv the color bodies in said oil, filtering out the decolorized oil, passing said decolorized oil to a second rotary disk, separatelyconducting caustic neutralizing agent to said second disk, rotating said second disk at a relatively high peripheral speed to cause said materials to flow across said disk in a thin film under substantial centrifugal force whereby immediate neutralization of the fatty acids is accomplished, removing the mixture of oil and neutralized acidxin a continuous film into a liquid receiving zon without forming an emulsion of the oil, .the amount of caustic, neutralizing agent being slightly in excess or the amount theoretically required to neutralize the acid, the

time of contact of neutralizing agent with the" charge oil, the uniform dispersion of neutralizing agent with respect to the dispersion of thg 1 acid in the oil film and the amount of neutraliz ing agent being suchthat the acid is neutralized in preference to any reaction of the neutralizing agent with the oil.

5. An improved-method for neutralizing'animal and vegetable oils as claimed in claim 1 in which the neutralized fatty acids are solvent treated to remove additional oil, saidoil being combined with theacid-free oil'previously made.

l6. An improved method for'neutralizing animal and vegetable-oils asclaimed in claim 4 in "which the neutralized fatty acids are solvent treated to removeadditlonal, oil, said oil being combined with the acid-free oil previously made. 7. The process of refiningvegetable oils, which comprises treatingsaid oils to remove gums contained thereingth'ereafter mixing a body of said oil with an alkali refining agentand' settling the resulting .soap stock from the oil to produce a soap stock-oil mixture substantially free of gums, withdrawing refined oil fromsaid setoil with an alkali refining reagent and settling the resulting soap stock from said oil, withdrawalkali refining reagent and settling from said oil a soap stock substantially free of gummy material,fand thereafter diluting the soap stock with water to form a flowable mixture and continuously 'centrifugally separating additional oil from said soap stock. I

13. A process of refining vegetable oils containing gums and free fatty acids,. which comprises continuously mixing a degumming reagent with said oil to precipitate said gums and continuously centrifugally separating said gums from said oil, thereafter admixing a body of said ing refined oil from said settled soap stock and admixing the remaining soap stock containing entrained oil with a diluting agent and con- 7 tinuously centrifugally separating additional retled soap stoclnand thereafter dilutingythe soap i stock and separating additional oil from said 7 soap stock. I

'8. A process of refining vegetable oils-contain ing gums and free fatty acids, which comprises continuously mixing a degumming reagent with said oil to precipitate said gums and'continuously centrifugally separating said gums from said oil, thereafter admixing a body of'saidoil with an alkali refining 'reagent 'and settling the resulting soap stock from said oil, withdrawing refined oilfrom said settledsoapstock and'admixing the remaining soap stock containing entrained ;oil with a dilutingIagent, and separatingoilfromsaidsoapstock.- I

fined oil from said soap stocklr 14. A process of refining vegetable oils containing gums and free fatty acids, which come prises continuously mixing a degumming reagent with said oil to precipitate said gums and I continuously c'entrifugally separating said gums from said oil, thereafter admixing a body of said oil with an alkali'refining reagent and settling said soap stock.

9. The process of refining vegetable oils; which 3 comprises treating said oils to remove gums conoil with an alkali refining reagent and settling the resulting soap stock fromthe oil-to produce a soap stock-oil mixture' subs'tantially meof gums, withdrawing refined oil from'said settled soap stock, and thereafter -dilutingthe soap stock with water and separating additlonal oil from said soap stock. I v

10. The process of refining vegetable oils, which comprisestreating said 0115. toxremovei gums contained therein, thereafter mixing a body of said oil with an alkalirefining agent and settling thev resulting soap stock from the oil" to produce a soap stock oil mixture'substanti'all'y free of gums, withdrawing refined oil from said settled soap stock and-thereafter diluting the soap stock with water to form a 'fiowable-mixture' and continuously*centrifugally separating additional 'oil'fro'm said soap stock.

llp'lhe process 5 of refining vegetable oils,"

which comprises subjecting an oil which issubincluding admixing abody'jof said oilwith an terial, and thereafter diluting; the soap stock to form a flowable mixture and separating addi-f tional refined oil from said s oap stock.

15. The'contlnuous prbcess of treating vegetable oil containing phosphatides, non-fatty matter and free fatty acicIscomprising the steps '01 mixing a stream of water which will precipitained therein, thereafter mixing a body of said time said phosphatides and non-fatty matter with'a stream of oilin suflicient amount and concentration to substantially completely pre-.

cipitate the same without destruction of said centrifugally separating the precipitated material from the oil, promptly mixing a stream of an alkaline refining reagent with a stream of the resultant oil in sumcient amount and concentration to substantially completely react with the fatty acids therein to form soap stock, and

- promptly thereafter centrifugally separating said soap stock from said oil toproduce a substantially'pure soap stock. v

16. A quickand continuous process for treating vegetable oils containing gums, which comprises the steps of: continuously admixing water as a precipitating reagent in an amount sufiicient toprecipitate said gums but without substantially reacting with the fatty acids contained therein; promptly, before injury to the stantially free'of gummy material to treatment 12. The process of refining vegetable out;

which comprisessubjecting an oil which is sub f stantially free of gummy material totreatment including admixing a body of said oiljwith an oil, continuously centrifugally separating the precipitated gums from said oil; promptly continuously mixing a neutralizing reagent with the thus 'degummed oils in sufficient amount to substantially completelyneutralize the free fatty acids remaining therein and toiform foots and promptly continuously centrifugally separating the foots from the thus refined 'oil.

. IRVIN'K. GILES.

MEAD CORNELL. WILLIAM KELLEY.

CERTIFICATE OF CORRECTION. 1 Patent No. 2,557,0h1. December 21, 1 1

IRVIN K. GILES, ET AL.

Itis hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 2, first column, lines 20 and 21, for 'decolorified" read --decolorized; page LL, second cQlumn, line 57, claim 16, after "the" insert --free-; and that the said Letters Patent sho'dld be read with this correction therein that the sane may oonfonn to the record of the case in the Patent Office.

Signed and sealed this 29th dsyL'of February, A. D. 19%.-

- Leslie Frazer (Seal) Acting Commissioner of Patents.

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