US2392973A - Process of refining oil - Google Patents

Description

Jan. 15, 1946. B. CLAYTON PROCESS OF REFINING OIL Filed July 17, 1941 Ben SOAP STOCK mm W H WM 3 G 0 a A W L w 1 E u L TL m A u m E a w m N .1 N

G 7, MN TN UE A5 6% R6 5 mA 0 H E 3lw E m Patented Jan. 15, 1946 PROCESS OF REFINING OIL Benjamin Clayton, Houston, Tex., assignor, by

mesne assignments, to rated, a Texas partnership Application July 17, 1941, Serial No. 402,855

13 Claims. (Cl. 260-898) Thi invention relates to a process of refining fatty oils and more particularly to a process of refining animal and vegetable oils in which the oil is neutralized but in which certain of theconestituents which are removed in conventional re'-' fining processes areleit in the oil to produce,a

' new oil product having certain desirable uses.

In 'therefining of vegetable and animal oils caustic alkalies have been conventionally employed to remove not only the-free fatty acids but gums including phosphatidic material'and as far as possible the coloring matter of the oil.

The oils resulting from such refining processes are substantially pure glycerides.

In accordance with the present invention the free fatty acids within the animal and vegetable oils are neutralized and removed in the form of soap and a portion of the gums are removed along with some of the coloring matter. The finished oil however contains a small amount, for example, to 1 6% of phosphatidic material intimately associated with the oil and this phos phatidic material imparts extremely valuable properties to the oil for many purposes for which the oil may be employed. Since the color of the oil is ordinarily not drastically reduced the present process is particularly applicable to light colored oils such as corn oil, but if a dark colored oil is not undesirable, the process may be employed for darker colored oils such as cottonseed oil.

I have found that if the I relatively high temperature while it contains all or a substantial portionof its original gums, some of the phosphatidic material remains intimately associated with the oil and is not removed by the refining steps. The. heating of the oil may be performed before any refining agents such as degumming or neutralizing agentsare added to the oil or while such agents are present, so long as the heating is accomplished before separating substantially all of the gums from the oil. Thus the, present process may have several modifications.

One modification of the process of the present invention includes a degumming step followed by a refining step in which a. non-saponifying refining agent is employed. It has been found that the oil may be pretreated so that the degumming on is subjected to a and neutralizing steps of the present invention toremove suspended or dissolved soap or alkali g, Unincorpofrom the oil without materially diminishing the amount of phosphatidic material left in the neutral oil.

It has been found that preheating the oil including a phosphatidic material, to a relatively high temperature but below that at which a major portion of the gums are. thrown out of solution to produce a break, will set the phosphatidic material in the oil so that degumming or alkali refining steps or both may be carried out to leave a substantial portion of the phosphatidic material in the oil'intimately associated therewith. Thus a neutral oil may be produced which contains a substantial amount of phosphatidic material which is much more stably held by the oil than phosphatidic material added to the neutral oil after refining. After the heating step referred to the oil may be cooledto any desired refining or degumming temperature. Employment of non-saponifying neutralizing agents such as soda ash in the alkali refining step is preferred asa larger portion of the more desirable phosphatidic materials is retained in the oil after refining.

The preferred process of the invention may be carried out in the apparatus shown in the drawing in which 5 indicates a source such as a tank for the crude oil to be refined which tank may include a heating coil 6, I indicates a source such asa tank for the degumming agent. The crude oil may be withdrawn from the tank 5 by a proportioning pump 8 and delivered through a heat exchanger 9 including a coil i0, and a second heat exchanger ll including a coil l2, to a mixer l5. The degumming agent may be withdrawn from a tank I by means of a proportioning pump it and delivered through a heat exchanger ll including a coil iii to the mixer ii. The proportioning pumps 8 and I6 are shown as being driven by a motor IS with a change speed device 20 positioned between the pumps. However, any other suitable type or proportioning equipment may be employed instead of the proportionin'g equipment shown. Themixer i5 may he of any suitable type such as a mechanical mixer but is preferably, of the flow type disclosed in the patent to Benjamin H. Thurman, No. 2,142,062, granted December 27. 1938. This mixer rapidly produces an intimate mixture between the oil and degumming agent. v

The resulting mixture may be passed through another heat, exchanger 2! provided wtih a coil 22, and then delivered to a continuous centrifugal separator 24 from which the partially degummed oil is delivered as the light eiiluent through a spout into a container 28 and the gums are delivered as the heavy ei'lluent-through a spout 21 into a container 28.

The gums may be discharged from the process but the oil in the container 26 may be withdrawn therefrom by means of a proportioning pump 30, passed through a heat exchanger 3| provided with a coil 32 and delivered to a mixer 33.. The neutralizing agent may be withdrawn from a source of supply shown as a tank 34 by a proportioning pump 35 and delivered through a heat exchanger 86 provided with a coil 81 to the mixer 33. The proportloning pumps and are shown as being driven-by a motor 38- with a change speed device 38 between the pumps but any suitable type of proportioning apparatus may be employed instead of the proportioning apparatus-- shown. The mixer 33 may be of any suitable type such as a mechanical mixer, but is preferably'oi the flow-mixer type referredto relative to, the mixer lI.---

y The resulting mixture of oil and refining re-, agent produced in-the mixer. .33 may be passed through another heat exchanger 4| provided with a coil 42-and delivered into a dehydrating chamber 43 so as to flow down the walls oi the dehydrating chamber. A relatively high vacuum is preferably maintained in the dehydrating chamber 43 by means oia vacuum pump 44 operating. through a condenser 45 provided with a receiver 46 and an entrainment separator 41. Heat may be supplied to the vapor separating chamber 41 imany suitable manner, 'for example, by means of' aheating coil- 48 positioned in the evaporating chamber belowthe liquid level therein. A substantial amount or water and other volatile materials maybe removed from the mixture in thevapor separating chamber 43 andpreierably taining phosphatidic material may be heated to "set the gum therein will vary with different oils but will usually fall between 200 and 450 F.

In some cases this temperature may be even higher but should not be high enough to throw the gum or phosphatidic materials out of solution to produce a break" which usually takes place at about 500 to 600 F. By heating the oil as above describedthe phosphatidic materials become set or changed in character so that they become more resistant to removal or destruction by the reagents employed to degum or neutralize the oil.

The heating referred to may be accomplished in a continuous manner in the heat exchanger 9. the heat exchanger I I bein employed to again cool the oilto a desired temperature for a subsequent step in the process. Usually a very short time of treatment at the high temperature is sufiicient, but if desired, the coil iii of the heat exchanger 9 can be of sufficient length to provide a longer time of treatment or a plurality of heat exchangers in series can be employed.

. Alternatively the crude oil can be heated in batch the -mixture is substantially completely dehydr'atedtherein. The dehydrated mixture may be withdrawn from the vapor separating chamber -43 by means of a pump and delivered to a mixer ii. A hydrating agent may be' withdrawn froma sourceof supply by a proportionlng pump 53 and also delivered to the mixer l I. The

pumps 48 and 53 may be driven by a motor 54 and: have a variable speed device 58 positioned between the pumps. The mixture from-the mixer 5| may be delivered through a heat exchanger 51 to a continuous centrifugal separator 58 from which the neutral oil is discharged as-the light emuent through a spout 59 into a suitable container 60 andthe soapstock is discharged as the heavy 'eiliuent through a spout 6| into a suitable container '82,

The dehydration in the vapor separating chamber 43 followed by hydration in the mixer 5! provides for excellentxseparation-oi' the soapstock in the tank 6 to therequired temperature and the heat exchanger 8 eliminated or by-passed.

Any suitable type of degumming agent which has no deleterious efiect upon the oil may be mixed with the crude oil in the mixer l5. Thus, water alone or water containing a small amount of an electrolyte may be employed. Nearly any electrolyte such as very small amounts of strong acids or bases or relatively larger amounts of weak acids or bases or salts either neutral or having acidic or basic reactions may be employed. For example, boric acid is an effective degumming agent even when used in extremely dilute solution and has the added advantage of bein an extremely eflective preserving agent for the gums separated from the oil. Thus the preferred degumming agent is a weal: solution of boric acid but dilute solutions of neutral or slightly acidic salts are also extremely eilective. Since in the present invention it is not desired to remove all of the gums, water alone is many times suiiicient and has been satisfactorily employed and if other degumming agents are employed. weak solutions of the less drasticagents are ordinarily employed.

Separation of gums from the oil is most eifective at temperatures somewhat above atmospheric, for example. between and F. although temperatures somewhat below this range and also above this range up to approxi: mately F. have been employed. The best temperature of mixing'will vary with different oils certain of which respond better to relatively high temperatures of mixing and others to lower from the oil even though a non-saponifying neutralizing agent is contemplated in the present invention, which type agent ordinarily produces a soapstock which is extremely dimcult to separate from the neutral oil. In certain cases, however, sueh soapsto'ck can 'be adequately separated from the on without del'iydratiomparticularly-i! relatively'large excesses of the non-saponifying' neutralizing agent are'employed and the resulting mixture is diluted with a substantial quantity of a hydrating agent. In such cases the vapor separating chamber maybe by-passed. This can be accomplished by passing the mixturefrom. the heat exchanger 42 through the p p It by closing the valves 84 and 6! and opening the valve ti pipelt The temperature to which the crude'oil contemperatures, but. the mixing temperature will usually fall between 80 and 160 F. By employing the heat exchangers III, II and I I to sub-- tract or add heat to the oil, degumming agenh or mixture, any desired temperature of mixing and separation can be secured. With most oils 1 it is sufficient to cool the oil in the heat exchanger ll so that mixing a degumming agent at room temperature with the oil will produce the desired separating temperature.

The neutralizing agent of the present invention is preferably a non-saponifying neutralizing agent, soda ash being preferred because of its excellent action as well as its cheapness and avail a ability. Non-saponifying neutralizing agents neutralize the free fatty acids without attacking the neutral oil and in this respect are distinguished irom'caustic alkalies which will saponify neutral oil. Thus the neutralizing agents may in general be any salt of a strong base and a weak acid, for example, trisodium phosphate, sodium acetate, etc. Also other materials having an alkaline reaction and not attacking neutral oils. such as ammonia or amines, for example, triethanolamine may be employed as a non-saponi tying neutralizing agent. Even caustic alkalies may be employed if used in amounts not substantially greater than that necessary to neutralize the free fatiyacids.

The most effective temperature of mixing with the neutralizing agent will vary with diiierent oils and different neutralizing agents and such temperature may be secured by either heating or cooling the degummed oil fromcontainer 26 or the neutralizing agent or both in the heat exchangers 3! and 36. Thus the temperature of mixing will vary within a wide range but will usually fall within 80 to 160 F.

Substantially any of the neutralizing agents almost immediately neutralize the free fatty acids when intimately mixed with the cilia the mixer from the soap in the vapor separating chamber 43. Such temperatures may be varied between 180 and 212 F. for ordinary operations,- but in [some cases it has been found desirable to employ much higher temperatures in the vapor separating chamber 43, for example, temperatures up to 450 F. in order to remove volatile materials having an undesirable odor found in some oils. Additional heat may be supplied to the materials in the vapor separating chamber 43 by the heating coil 48 is desired.

The hydrating agent mixed with the dehydrated oil-soapstock mixture withdrawn from the vapor separating chamber 43 may be any aqueone medium which will hydrate and weight the soapstocl: of the rehydrated mixture. Thus water alone may constitute the hydrating agent although this agent preferably comprises an aqueous solution of a substantial neutral salt or salts, particularly those having separating promotion properties such as sulphates, or thiocyanate of alkali metals. although solutions of salts having a basic reaction may be employed. The temperature found most suitable for separating a particular mixture may be obtained by heatins. or cooling the mixture in the heat exchanger 51, and this temperature will ordinarily range be tween 100 and 160 F. although in some instances higher temperatures may be employed. The various heat exchanger illustrated can thus be employed to heat or cool the materials passed therethrough depending upon the oil being treated and the agents employed; they can be used to provide additional reaction time for mixtures passed therethrough in which case no heat I may be added or subtracted: or. they can be eliminated from the apparatus if not a particular operation.

The process is preferably carried on so that a substantial amount of phosphatidic material renecessary for mains in 'the oil discharged into the receiver 62 from the centrifugal separator 5|. The high temperature pretreatment of the oil containing gums makes a portion of the phosphatidic material extremely difllcult to remove by degumming and refining steps and, in general, a substantial amount phosphatidic material remains in the oil even after relatively drastic alkali refining steps.

.However, bycorrelating the temperature and time ofthe pretreatment with the amounts and concentrations of the agents and conditions employed in the subsequent steps, the amount of bound phosphatidic material in the final oil may be varied. Thus for a particular pretreated oil. .a' degumming agent is selected and its amount and concentration adjusted so that a substantial amount or the gums is discharged with the oil through the spout 25 of the separate;' 24. The gummy materials retained in the oils are to a large extent phosphatidic and depending upon the amount of this material removed by the degumming agent and conditions employed in the degumming step theamountoi gums remaining in the oil discharged into the receiver 25 may vary, for example, from 341 to 1%. With this oil fed to the neutralizing, step and mixed with a neutralizing agent of sufliciently low concentration or amount a final oil delivered to the recelver 60 may be obtained containing, for exp e. A0 to 550% of phosph'atidlc' material. In

general the only subsequent treatment needed to remove traces of other impurities in the oil is asteps above described are advantageous in certain cases since a more selective action upon phosphatidic material retained in the oil is secured thereby, the gums from the degumming step constitute a valuable by-product, and the soapstock from the neutralizing step is of higher quality. It is possible, however, to carry out both degumming and neutralizing in a, single step, as the non-saponitying neutralizing agents will also function as partial degumming agents to still produce an oil containing associated phosphatidic material. Also it is not necessary to cool the oil after it has been heated to the phosphatide or gum setting temperatures before adding a degumming agent or non-saponifying neutralizing agent. That is to sa the high temperatures in such cases set the phosphatidic material in the oil even in the presence of a degumming or non-saponifying neutralizing agent. Thus it is also possible to first add such an agent at a relatively low temperature and then bring the mixture to the gum setting temperature.

The heated mixtures resulting from such operations ma then be cooled to a desired separating temperature or. in some instances may be separated at the elevated temperature or in case a non-saponifying neutralizing agent is employed the mixture may be delivered directly to. a

vapor-separating zone without cooling. I

In any event the phosphatidic material remaining in the neutral oil is more intimately associated or bound with the neutral oil than is the case where nhosuhatidic materials are later added to anoil-from which substantially all .of the phosphatidic materials have been re-' moved. The neutral oil containing phosphatidic material resulting from the process of the present invention is extremely stable against oxidation or the acquiring of disagreeable odors when compared with oils from which all of the phosphatidic material has been removed or even the latter oil .to which phosphatidic material has been added. Since phosphatidic materials are valuable ingredients in margarine and shortening the oils of the present invention may be employed therein either as compounding oils with harder fats or after hydrogenation. Since the present process does not reduce the color of the oil to the extent secured in processes employing large excesses of caustic alkalies, the process is particularly valuable with light colored oils such as corn oiL but ma be employed in the production of neutral oils containing phosphatidic materials in which a dark color is not objectionable. The invention is also particularly applicable to vegetable oils, but the other glyceride oils such as animal oils also usually contain phosphatidic materials analogous to those found in vegetable oils, and may also be treated by the present invention. The continuous process disclosed enables a high quality oil to be produced with low losses but it is apparent that at least certain of the steps may be batch operations.

By the employment of the term set in the product claims, I intend to embrace and be restricted to a product in which the phosphatidic material,' as originally contained in the oil, has

been treated in such a way that it is incapableof removal by an aqueous separation during the separation of the soap'stock from the refined product, irrespective of whether separation of the phosphatidic material is attempted by centrifuging, filtering or settling, whereby such material becomes intimately a part of the oil and performs the functions and advantages herein described.

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

- I claim:

i. In the process of recovering a neutral oil from crude fatt oils containing gums including phosphatidic material, which process includes mixing said oil with a non-'saponifying neutralizing agent and separating the resulting soap stock from said oils in the presence of substantial amounts of water, the improvement which comprises, supplying sufilcient heat to said oil prior to separating said soap stock therefrom to set a substantial portion of said phosphatidic material therein but insufficient to cause gums to be rendered insoluble in dry oil, to thereby produce a substantially neutralized oil containing a substantial amount of said phosphatidic material after separation of said soap stock.

2; In the process of recovering a, neutral oil from crude fatty oils containing gums including phosphatidic material, which process includes mixing said oil with a non-saponifying neutralizing agent and separating the resulting soap stock from said oils in the presence of substantial amounts of water, the improvement which comprises supplying suflicient heat to said oil prior to separating said soap stock therefrom to raise the temperature thereof to between 200 and 450" tion -01 said phosphatidic material therein-and f produce a substantially neutralized oil containing a substantial amount of said phosphatldic material after separation of said soap stock.

3. In the process of recovering a neutral oil from crude fatty oils containing gums including phosphatidic material, which process includes mixingsaid oils with an aqueous 'degummlng agent, separating the resulting foots containing water from the oil, mixing the resulting oil with a non-saponifying neutralizing agent and separating the resulting soap stock from the neutral oil, the improvement which comprises, supplying suflicient heat to said oil prior to separating said fonts to raise the temperature thereof to a degree which will set a substantial portion of said phosphatidic material therein but insuiiicient to cause gums to be rendered insoluble in dry oil, to thereby produce a substantially neutralized oil containing a substantial amount of said phosphatidic material after separation of said soap stock.

4. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amounts of phosphatidlc material, which comprises, mixing said oil with a non-saponifying neutralizing agent, heating said mixture to a temperature sufiiclently high to set a. substantial portion of the phosphatidic material therein but insumcient to cause gums to be ture to a temperature sufilciently high to set a substantial portion of the phosphatidic material therein but insufilcient to cause gums to be rendered insoluble in dry oil. separating gums from said oil, thereafter neutralizing the resulting oil with a non-saponifying neutralizing agent and separating the resulting soap stock therefrom to produce a substantially neutralized oil containing a substantial amount of phosphatidic material.

6. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amountsof phosphatidic materlal, which comprises, preheating said oils containing gums to a temperature sufiiciently high to set phosphatidic material therein but insufficient to cause gums to be rendered insoluble in dry oil, thereafter mixing the resulting oils with a non-saponifying neutralizing agent and se arating the resulting soapstock from the neutral oil in the presence of substantial amounts of water to produce a substantially completely neutralized oil containing a substantial amount of phos- Phatidic material.

7. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil conhigh to set phosphatidic material therein but insufiicient to cause gums to be rendered insoluble I". and sufficiently high to set asubstantial porin dry oil, thereafter partially degumming the resultant oils with an aqueous degumming agent under conditions which leave a portion of the gums in the oil, thereafter neutralizing the partially degummed oils with a non-saponifying neutralizing agent, and separating the resulting soap stock therefrom under conditions leaving a substantial amount of phosphatidic materials in the neutral oil.

8. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amounts of phosphatidic material, which comprises, heating the oil containing gums to a temperature sufllciently high to set phosphatidic material therein but insufficient to cause gums to be rendered insoluble in dry oil, thereafter partially degumming the crude oil with an aqueous degumming agent in sufllciently small amount to leave a substantial portion of the gums therein, thereafter neutralizing the resultant oils with a neutralizing agent in suflicient amount to substantially completely neutralize the resulting on, but insufllcient to precipitate all of the phosphatidic material, and separating the resulting soap stock from the'neutral oil to produce a neutral 011 containing a substantial amount of phosphatidic material.

9. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amounts of phosphatidic material, which comprises, heating the crude oils to a temperature sufliciently high to set phosphatidic material therein but insufiicient to cause gums to be rendered insoluble in dry oil, thereafter mixing the stream of the oil containing gums with a stream of aqueous degumming agent in an amount insumcient to precipitate all of said gums, delivering the combined stream to a continuous cen- I trifugal separator and continuously centrifugally separating a portion of said gums from said 011 to produce a partially degummed oil, continuously mixing a stream of said partially degummed oil with a stream of a neutralizing agent in sufflcient amount to substantially completely neutralize said partially degummed oil but insomcient to precipitate all of the remaining gums therein, delivering the resulting stream to a continuous centrifugal separator and separating the resulting soap stock resulting from the neutral oil to produce a substantially neutral oil containing a substantial amount of phosphatidic material.

10. The process of refining crude animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amounts of phosphatidic msterlal. which comprises, heating said crude oil to a temperature sufllciently high to set phosphatidic material therein but insufllcient to cause gums to be rendered insoluble in dry oil, cooling the heated oil, and mixing therewitha non-saponifyin'g neutralizing gent and separating the resulting soap stock in the presence of substantial amount of water from neutral oil containing a substantial amount of phosphatidic material.

11. The process of refining animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containin phosphatidic material, which comprises, heating said oil to a temperature sumcient to set phosphatidic material therein but insufllcient to cause gums to be rendered insoluble in dry oil, cooling the heated oil and mixing therewith an aqueous degumming agent to precipitate a portion of said gums, separating the precipitated gums from the resulting oil and thereafter neutralizing said resulting oil and separating the resulting soap stock therefrom to produce a neutral oil containing substantial amounts of phosphatidic material.

12. The process of refining animal and vegetable oils containing gums including phosphatidic material to produce a neutral oil containing substantial amounts of phosphatidic material, which comprises, heating the oil containing gums to a.

terial, said product being substantially neutraland being substantially free of gums other than phosphatidic material but containing a substantial amount of "set phosphatidic material which 'is not removed from the oil by precipitation with water and centrifugation, settling or filtration and which is thus contradistinguished from identical oils having such phosphatidic material added thereto, said product being further characterized by heat treatment of the oils following refining prior to separation of the resultant soap stock, to an extent sufllcient to "set" the said phosphatidic material and to render the same inseparableby water precipitation and centrifugation.

BENJAMIN CLAYTON.

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