US2122260A - Deodorizing and bleaching oils - Google Patents

Description

June 28, 19u38.

l.. c. MooRE ET AL 2,122,260

DEODORIZING AND BLEACHING OILS Filed Dec. 6, 1932 2 Sheets-Sheet 1 (klamm ATTORNEY.

June 2s, 193g. L, MOQRE ET AL 2,122,260

DEDORIZING AND BLEACHING OILS www ATTORNEY.

Patented June 28, 1938 DEDORIZING Ll" BLEACIHIHNG @MJS Landon C. Moore, Dallas, and Arthur C. Norman, deceased, late of New Boston, by Smithia S. Norman, executrix, New Boston, Tex.

Application December 6, 1932, Serial No. 645,882

7 Claims.

This invention particularly relates to the bleaching of the vegetable oils, cottonseedy cocoanut, soya bean, sesame and corn oils. It further relates to the bleaching and deodorizing of said oils.

Primary objects of the invention are to effectively bleach vegetable oils specified, to do so at a reduced cost, and to effect the bleaching and deodorizing of said oils in a combined and eflicient manner.

It is Well known to those skilled in the art of producing certain edible vegetable oils that a crude oil is usually subjected to three general processing steps generally termed refining, bleaching and deodorizing. Of these, the socalled rening step consists of mixing the crude oil with an aqueous solution of caustic soda so as to form probably, sodium salts with the free acids, tri-glycerides and others of the impurities present in the crude product and then separating the purified oil from the aqueous portion of the mixture and any precipitated solids so as to yield a product free from moisture and precipitated or solid substances. The so-called bleaching step consists of warming the rened oil, employing and intimately mixing with it a solid decolorizing reagent such as fullers earth and then separating the solids'from the oil by means of suitable filtration apparatus, so as to yield a product of much improved color and free of solid impurities. The so-called deodorizing step includes heating the rened and bleached oil to and holding it at a temperature of substantially 325 degrees Fahrenheit in a closed vessel under a high vacuum and simultaneously blowing superheated steam through the hot oil to volatilize objectionable ingredients and to yield an oil of suitable taste and odor.

The use of a solid decolorizing reagent in the bleaching step of the prior art process is attended (a) by an appreciable expense for said reagent which generally is used only once and then discarded, and also (b) by an appreciable loss of oil with the discarded reagent.

- The essence of the present invention may be said to reside in the employment of heat, under certain requisite conditions, as the essential element in effecting the bleaching of the above specied rened oils; and further in effecting in a substantially single processing operation the bleaching and the deodorizing of said oils. The operation is eected in a system, which is closed to exclude air and which is maintained under vacuum effect during the operation, (a) by heating the oil to a critical temperature substantially 5 as high as can be employed with substantially no volatilizing, scorching or change in the essential characteristics of the oil as, for example, by polymerization, while an inert gaseous medium is continuously introduced into the system and is thoroughly dispersed through or contacted with the oil within same, and then (b) by reducing to and holding for a period of time at a somewhat lower point, the temperature of the oil in the system while continuing the main- 1- tenance of the vacuum and the introduction and dispersion of the inert gas, and then (c) by nally cooling the oil while continuing to maintain the oil out of contact with the air as by the maintenance of the vacuum eiect. The larger por- 20 tion of the decolorizing eiect with some deodorizing is effected in the first step of the operation, and a larger portion of the deodorizing with some decolorizing is effected in the second step.

Thus the invention has for a primary objective 2- the elimination of the use of fullers earth and other solid bleaching reagents together with the loss of oil attendant to the use of such reagents.

Thus, too, it has for an objective the combining of what has heretofore constituted two separate and distinct and unrelated operations, one for bleaching and one for deodorizing, into substantially a single operation of steps.

Thus the nature of the invention may be said to reside in heating the oil to be treated in a closed vessel to a temperature as high as can be done without danger of volatilizing the oil or burning it, while agitating the oil to disperse an inert gaseous medium thoroughly therethrough, during which operations, the oil is exposed to the action of a vacuum.

The invention may be carried out by exposing the oil, or oil bearing mixture being treated, simultaneously or concurrently to bleaching and to deodorizing actions without the use in the zone of treatment of solid bleaching agents such as fullers earth, bone char, or activated carbon. This bleaching and deodorizing is accomplished by raising the temperature of the oil while under the action of a vacuum or vacuum effect, to a critical bleaching temperature range within which the color substances are affected without burning or volatilizing the oil and within which some portion of the odorous organic substance is removed by volatilization. The range of operating temperatures within which the decolorizing just referred to is carried out and within which the substantial decolorizing operations are confined, is thus referred to herein as the operative critical bleaching-temperature range. Then While still maintaining the oil under vacuum, Washingout volatilizable impurities, odoriferous or otherwise,` from the oil by means of an inert gas, such as steam. And finally cooling the treated oil while still under a vacuum.

In the interest of clarity it is herein pointed out that the term bleaching, as employed in describing this invention, may be defined as a change in the color of a refined vegetable oil essentially the equivalent of that change obtained when that oil is subjected to the official bleaching test as set forth in Rules Governing 'IransactionsBetween Members of the National Cot- 300 gms. of refined oil into a refining cup, heat to 120 C. and add 6 per cent. of oiiicial fullers earth. Stir mechanically at 250, R. P. M. (plus or minus 10) for lve minutes, not allowing temperature to fall below 105 C'. and filter through filter paper. After suiiicient oil has passed the filter to insure clearness, collect a sample for color reading. Cool and read immediately.

The oiiicial fullers earth prescribed above is to be obtained from the secretary of the American Oil Chemists Society as set forth in the rule (120 C. is equivalent to 248 F.-105 C. is equivalent to 221 F.).

The invention may be carried out in different apparatus but only one arrangement thereof is illustrated in Fig. 1 of the accompanying drawings and even that arrangement is shown more orv lessrdiagrammatically. The curve A-BC of Fig. 2 of the accompanying drawings illustrates substantially a type of temperature-time relationship employed in effecting the invention by the combined steps of bleaching and deodorizing and as Vapplied ,to cotton seed oil. The curve D--E-F of Flug. 2 substantially illustrates the color-time relationship resulting from the use of the time temperature relationship illustrated by the curve A-B-C.

The curve M--N-O of Fig. 3 of the accompanying drawings is embodied herein to illustrate an application of the invention as applied to cottonseed oil, wherein the bleacher step is the main feature involved. The curve X--Y-Z of this Fig. 3 substantially illustrates the corresponding color-time relationship illustrated by the curve M-N-O.

In the drawings there, are shown an oil heater II of any mutable type, a primary oil yheating tank or kettle I2 and a.v plurality of secondary oil treating tanks or kettles I3, It and I 5, usually similar to kettle I2. And associated with the kettles, is a cooler I6 `of any emcient type.

.The kettles Yare all connected to an oil discharge pipe line I1 but are iprovided with outlet valves I8, I8, 20 and 2| respectively. 'There is a pump lineyis indicated at 26 with a valved connection 31, 38, 39 and 40 for each kettle respectively, and each such connection is provided with a steam gauge 4|, 42, 43 and 44 respectively. 45, 46, 41 and 48 represent a vacuum gauge `on each kettle respectively; 49, 50, 5| and 52a thermometer; and 53, 54, 55 and 56 a gauge glass and sampler.

The steam line 36 .has a feed inlet pipe 51 and also a valved outlet 58 to an injection device 59 adjacent the pump 22.

The oil line I1 has an inlet 60 for new oil to be treated controlled by a three-way valve 6|. The oil line |1 terminates at a pump 62 for impelling finished oil from a kettle along pipe 63 to the cooler I6. A valve 64 is provided in the pipe 63, and another valve 65 is provided in pipe I1. Each kettle has in its bottom a steam dispensing device such as a spider 66 having substantially radial pipes 61 through which steam is fed from steam pipe 31 for instance, and the steam is emitted through apertures in the bottom or underside of the pipes 61. The cooler I6 -has an outlet or discharge pipe 68 leading to a filter or filter-press which is not shown. The cooler may be provided with cooling coils 69 and an agitator 10, although other types of coolers may be used.

The operation of this apparatuson refined cotton seed oil, for instance, is as follows: Through oil inlet 60, oil is fed to the system including primary kettle I2 and heater II until kettle I2 is about half full.

The vacuum line 30 is opened to the kettle I2 and its contents by means of valve 3| so there is a vacuum of approximately 29" acting on the oil in the kettle.

The pump 22 causes continuous'circulation of the oil from the kettle I2 through the heater |I and back to the kettle through pipes 24 and 25. Thus the oil in kettle I2 is gradually heated to the desired temperature which for cotton seed oil is about 460 F. In this connection see curve A-B-C of Fig. 2 which is illustrative of the steps described in this paragraph and the immediately following portions of this specification. During this circulation of oil from kettle to heater and return, it is helpful to inject steam into the oil going to the heater, for instance by injector 5B or other similar device, located preferably ahead 0f the pump. This steam has several functions but the prime one is to keep the oil in motion in flowing through the heater so that none of it will stagnate in the heater and be burned, in other words, there is caused continuous circulation of the oil whereby it repeatedly flows through the zone where the heating thereof is most intense and during which flow of the oil through or past said zone there is effected suiicient motion so that as indicated none of the oil being heated will stagnate or become pocketed in the heater or in any section thereof and thus be burned or scorched.

Then this hot bleached oil is conveyed to a secondary kettle I3 by closing valve 25 and opening valve 26, since the pump 22 causes the necessary circulation. During this transfer, the temperature of the oil in the secondary kettle I3 falls to about 435 F. superheated steam is diffused or dispersed through the oil or in other words is caused to iiow into the oil on its way through the oil, by means of valved connection 38 and its associated spider and arms. representatively indicated at 66 and 6l. The oil may stayin kettle I3 for an interval as long as three hours. meanwhile being exposed to action of a vacuum through pipe 30 and valve connection 32. The time of detention in the secondary kettle depends upon the degree of deodorization required of the nished oil, since deodorization goes on progressively. The temperature is indicated on thermometer 50, the steam pressure on gauge 42 and the vacuum on gauge 46. After a suitable time the steam supplied to kettle I3 may be lessened while increasing the vacuum, if possible in order to cool the oil down to say 350 F. Then the oil is pumped through pump 62 and pipe 63 to the cooler I6 by a suitable manipulation of the various valves. Here the oil while still .under a vacuum is cooled to approximately 150 F. whereupon it is discharged through pipe B3 to a ltration stage. The quicker the cooling takes place, the better for the flavor of the treated oil.

While oil in the kettle I3 is being treated, primary kettle I2 is refilled with oil which is heated, as the rstlbatch was. and then it is transferred to secondary kettle I4 for further treatment as described for the batch in kettle I3. Still another batch is heated in primary kettle I2 and then transferred to secondary kettle I5.

After kettle I3 has been emptied by having its treated oil pumped to the cooler I6, it is then ready to have a fresh batch of heated oil from kettle I2 pumped to it, and so on, each secondary kettle I3, I4 and I5 having heated oil from primary kettle I2 pumped thereto respectively, and from each kettle to the cooler. Thus by using a battery of kettles individually batch operated, the battery as a whole gives continuous treatment of oil.

In order to insure that the bleached oil is free of solid impurities which may be therein it is manifest that it may be filtered after the coollng.

This treatment simultaneously or concurrently bleaches and deodorizes the oil. Such action is produced by raising the temperature of the oil to a point within a range at which bleaching is effected without fundamentally affecting the oilin any deleterious manner as by volatilizing, polymerizing. or oxidizing the oil, then maintaining the oil at elevated but lesser temperatures for a period to produce deodorization, meanwhile exposing the oil to the action of a vacuum and dispersing through the oil superheated steam. The high temperature causes precipitation or change in the color imparting substances. These are washed out or eliminated from the oil by dispersing the superheated steam through the body of the oil. Their removal from the oil is facilitated by means of the vacuum. The maintained temperatures, which may be somewhat lower than the higher temperature range last above-mentioned, further-s volatilization of odorous free fatty acids and other impurities, but not of the oil. The temperature range within which this substantial deodorizing is carried out may be referred to as the deodorizing-temperature range. Agitation oi the oil by the steam being diffused therethrough aids this action. AThe use of the vacuum aims to prevent oxidation of the oil at the high temperatures to which it is heated. It also assists in volatilizing and removing from the place of volatilization the odorous impurities of the oil being treated.

The various vegetable oils listed lend themselves to this deodorizing and bleaching treatment, which eliminates the use of bleaching agents such as i'uller's earth or carbon. But each oil seems to have different requirements as to temperature that must be reached for best results. Each oil must be raised to a tempreature as high as possible without reaching its liash point, for it is imperative that during treatment the oil is not volatilized. To determine this, the flash point of the oil to be treated is observed and a factor of safety is deducted from that point. This factor has to be determined by tests to be sure of it. Some oils which respond to this treatment and their effective temperatures are:

Degrees Fahrenheit approximately Cotton seed oil 450-470 Seya. bean oil 475-480 Sesame oil 460-470 Cocoanut oil 400-410 Corn oil 450-460 The time of treatment varies with the oil and with the use to which the finished oil is to be put. The bleaching takes place in a critical range of high temperatures whereas the deodorization takes place concurrently but over a much longer period of time during which the oil is maintained at elevated temperatures but lower than those in the bleaching range. If the oil is to be used for non-edible purposes, it need not be deodorized so completely and therefore for not so long a time as if it were to be eaten. A curve indicative of this process is illustrated in Fig. 3 and is indicated M-N-O. But taking cotton seed oil for an example and as shown by commer'- cial scale operation typied by the curve A--B-C of Fig. 2, a satisfactory time of treatment is an hour in the primary heater to reach bleaching temperatures and three hours in the secondary kettle at the lower deodorizing temperatures. After such treatment, the cotton seed oil has its color changed from a red substantially towards white and the treated oil is neutral in flavor and odor.

In order that a reader of this patent may have ready reference for comparative purposes to flash point temperatures for certain oils there are inserted in this specification certain tables found on page 211 of Volume II, First Edition of International Critical Tables prepared by the National Research Council and published for said council by the McGraw-Hill Book Company, Inc.. New York, 370 Seventh Ave., in 1927.

On said page 211 thereof one nds the flash point temperature for cottonseed oil according to one portion of the table as having an average value of 523.0 degrees F. or 272.7 degrees C.,.with extreme values given as 500 degrees to 540 degrees F. or 260 degrees to 282.22 degrees C., while according to another portion of the table the flash point of cottonseed oil is listed as 582 degrees F. or 305.6 degrees C.

For linseed oil in the same table-probably raw oilthe flash point is given as 378 degrees F. or 192 degrees C., while for linseed oil boiled the flash point temperature is given as 419 degrees F. or 215 degrees C.

The tables referred to and which are being quoted read as follows:

FLASH PorN'rs or OILS AND FA'rs 1. Closed test Average value E53-ge Oil or iat F. C. F.

Olive 437. 5 225. 2 410-465 Arctic sperm 446. 2 230. 0 390-485 Southern sperm 457. 5 236. 3 420-485 Rape, Black Sea renne 464. 4 240. 2 430-490 N eats 470. 3 243. 5 410-540 White whale 476. 246. 4 430-530 Rape, E Indian refined- 478.6 248. l 410-510 Cottonseed 523.0 272. 7 50G-540 2. Methods not stated Flash Fire point point Oil or fat Linseed 378 192 572 300 Linseed, boiled 419 215 468 242 468 242 Maize (com) 'i--- 2537 Sperm, No. 2 574 302 Prime lard 644 340 Cottonseed 644 340 This invention can be used to effect the required bleaching of the oil while either completely or incompletely deodorizing it. Or it can be used on already partially bleached oil whereby completion of the required bleaching and the deodorizing can be carried on simultaneously.

The process of this invention can be carried out on the rened oils listed; on mixtures thereof or any of said oils listed or mixtures thereof with hydrogenated or semi-hydrogenatecl products thereof; and on mixtures of said oils in or any of said oils or products thereof on the one hand and stearin on the other. 'I'he process can be carried out in other apparatus than that shown herein so long as the temperature, time, gas and vacuum requirements are met. By way of example, the

l oil in the primary kettle may be heated indirectly instead of directly, and instead of primary and secondary kettles, a single kettle can be used if the volume of oill to be treated does not warrant more than one kettle.

What is claimed is:-

1. In the treating of refined cottonseed oil and analogues thereof such as are dened herein in order to overcome objectionable color characteristics thereof and in order to realize a decolorizing process according to which the objectionable color characteristics are overcome without the employment as an essential part of the decolorizing process of a solid bleaching agent such as fullers earth, bone char or activated carbon, the method which comprises heat treating the oil while agitating it, while dispersing therethrough a flow of an inert gaseous medium as superheated steam, while maintaining thereon' a vacuum effect, and While maintaining the oil substantially free from the influence of gases of oxidizing nature, which said heat treating involves heating the oil to temperatures within an operative critical bleaching temperature range having as its uppermost operative temperature one which is as areaaeo high as possible but which provides a factor of safety for the particular oil being treated below the flashpoint temperature thereof whereby, during said treating as carried out, there is substantially avoided volatilizing, polymerizing or burning of the oil during said heat treating, which critical range as employable for rened cottonseed oil lies between approximately 450 and approximately 470 degrees Fahrenheit, maintaining the temperatures of the oil within said range for a period of time which is insuiciently long for the oil being so heated to be changed fundamentally as by volatilization, polymerization, or burning, but long enough so that by virtue of said heat treating there .is effected a bleaching action in which the objectionable color characteristics of the oil are substantially destroyed; and which method also comprises subsequently cooling the oil before exposure to air.

2. The method of treating refined cottonseed oil and analogues thereof as defined in and by claim 1, and further carried out in such a manner that it comprises cooling the oil to a deodoi-, izing-temperature range extending between approximately 15 and approximately 120 Fahrenheit degrees below the temperatures employed within said bleaching-temperature range, maintaining the oil at temperatures within said deodorizing-temperature range for a period of time sufilciently long to eiect substantial reduction in the odorous characteristics of the oil, maintaining the oi-i under vacuum effect while substantially free from the influence of gases of oxidizing nature during said last mentioned period, and also during said last mentioned period flowing an inert gaseous medium as superheated steam into l ing process according to which the objectionable color characteristics are overcome Without the employment as an essential part of the decolorizing process of a solid bleaching agent such as fuller's earth, bone char or activated carbon, the

method which comprises heat treating the oil while agitating it, While dispersing therethrough a flow of an inert gaseous medium as steam, while maintaining thereon a vacuum eiect, and while maintaining the oil free from the inuence of gases of oxidizing nature, which said heat treating involves heating the oil to temperatures within but not above an operative critical bleachingtemperature range extending between approximately 450 and approximately 470 degrees Fahrenheit, maintaining the temperature of the oil Within said range for a period of time which is insuiciently long for the oil being so heated to be changed fundamentally as by volatilization, polymerization, or burning but long enough to effect a bleaching action the result of ywhich is that the objectionable color characteristics of the oil are substantially destroyed but at the most with only a slight concomitant reduction in the odorous characteristics of the oil; and which method also comprises subsequently cooling the oil before exposure to air.

4. The method of treating refined cottonseed oil as defined in and'by claim 3, and further carried out in such a manner that it comprises cooling the oil to a deodorizing-temperature range extending between approximately 435 and approximately 350 degrees Fahrenheit, maintaining the oil at temperatures within said deodorizing-temperature for a period of time sufficiently long to effect substantial reduction in the and analogues thereof such as aredefned herein,

in order to overcome objectionable color characteristics thereof and in order to realize a decolorizing process according to which the objectionable color characteristics are overcome Without the employment as an essential part of the decolorizing process of a solid bleaching agent such as fullers earth, bone char or activated carbon, the method which comprises heat treating said oil while under a maintained vacuum effect, while it is substantially free from the iniiuence of chemically reactive gases of oxidizing and deleteriously contaminating nature and while it is under conditions of agitation which will prevent excessivelocalized overheating, which said heat treating involves heating the oil to temperatures within an operative critical bleaching-temperature range having as its uppermost operative temperature one which is as high as possible, but which provides a factor of safety for the particular oil being treated below the ilashpoint temperature thereof whereby, during said treating as carried out, there is substantially avoided volatilizing, polymerizing or burning of the oil during said heat treating; maintaining the temperatures of the oil within said range for a period of time which is insufficiently long for the oil` being so heated to be changed fundamentally as by volatilization, polymerization, or burning, but

long enough to effect in the oil a bleaching action the result of which is that the objectionable y, color characteristics of the oil are substantially' destroyed; and which method also comprises subsequently cooling the oil before exposure to air.`

6. The method of treating refined cottonseed' oil and analogues thereof, such as are defined herein, in order to overcome vobjectionable color characteristics thereof, and according to which method certain objectionable color characteristics of the oil areovercome without the employment as an essential part of the bleaching operation thereof of a solid bleaching agent such as fullers earth, bone char or activated carbon, which said method comprises heat treating said oil while it is under the influence of vacuum and is substantially free from the inuence .of chemically reactive gases of oxidizing and deleteriously contaminating nature and under conditions which will prevent excessive localized heating, which said heat treating involves heating the oil to temperatures within an operative critical bleaching-temperature range having as its uppermost operative temperature one which is as high as possible but which provides a factor of safety for the particular oil being treated whereby, during said treating as carried out, there is substantially avoided volatilizing, polymerizing or burning of the oil during said heat treating; maintaining the temperatures of the oil within said range for a period of time which is insufiiciently long for the oil being so heated to be changed fundamentally as by volatilization, polymerization, or burning, but sufficiently long so that incident to such a heating a bleaching action follows with a consequent overcoming of certain color characteristics of the oil; and which method also comprises subsequently cooling the oil before exposure to air.

'1. In the treating of rened cottonseed oil and analogues thereof such as are defined herein, in order to overcome objectionable color characteristics thereof and in order to realize a decolorizing process according to which the objectionable color characteristics are overcome without the employment as an essential part of the decolorizing process of a solid bleaching agent such as fullers earth, bone char or activated carbon, the method which comprises heat treating said oil While it is under the influence of vacuum and While it is substantially free from the influence of chemically reactive gases of oxidizing and deleteriously contaminating nature and while under conditions which will prevent excessive localized heating, which said heat treating involves heating the oil to temperatures Within an operative critical bleaching-temperature range having as its uppermost operativetemperature one which is as high as possible but which provides a factor of safety for the particular oil being' treated whereby, during said treating as carried out, there is substantially avoided volatilizing, polymerizing or burning of the oil during said heat treating; maintaining the temperatures of the/ oil within said range for a period of time which is insufficiently long for the oil being so heated to be changed fundamentally as by volatilization, polymerization, or burning, but long yenough so that there is effected in the oil a bleachcomprises subsequently cooling the oil before exposure to air.

LANDON C. MOORE. ARTHUR C. NORMAN, Deceased,

By SMITHIA S. NORMAN,

Exccutr.

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