US1915260A - Process for treating oil - Google Patents

Description

June 20, 1933. w. F. HARRISON El AL PROCESS FOR TREATING OIL Filed Jan. 22, 1930 invention accomplishes these results.

Patented June 20, 1933 UNITED STATES PATENT OFFICE WOODFOBD F. HARRISON AND AUGUSTUS H. BATCEELDEB, OF BERKELEY, CALIFORNIA,

ASSIGNOBS To THE CALIFORNIA INK COMPANY INC., 015 WEST BERKELEY, CALI- FOBNIA, A CORPORATION rnocnss ron TREATING on.

Application filed January 22, 1930. Serial No. 422,669.

This invention relates to a novel method of producing oils havinga low fattyacid content.

Animal and vegetable oils generally have varying amounts of fatty acids of various kinds. For many purposes, it is extremely desirable to remove the fatty acids from the oils, as when the oil is used in the manufacture of paints, varnishes and printing inks, for example. Polymerized oils have a higher acid value, than oils which have not-been polymerized, because generally during the process of polymerization, the oil is increased due to the breaking down of the fatty glycerides thereof into fatty acids during the process of polymerization.

The aim of this invention is to provide an improved method of removing the fatty acids from vegetable or animal oils, that have a higher acid value than is desirable for the purpose or for the use to which the oil is to be put.

This invention is also capable of being used in reducing the acid value of oils, that are incapable of being polymerized, as well as to reduce the acid value of oils that have been polymerized. When polymerizable oils are treated it is preferable to simultaneously effect the polymerization of the oil, and the reduction. in the acid value thereof and this Polymerization, unaccompanied by oxidation, may be conveniently brought about in a closed system, by heat treatment of the oil to the extent necessary to bringthe oil to the temperature at which polymerization will occur. This temperature, of course, varies for diflering oils.

We have found that under proper conditions the fatty acids and other relatively volatile impurities contained in animal and vegetable oils, may be very conveniently and relatively inexpensively removed from the oils by distillation at temperatures at which polymerization occurs in oils that are capable of being polymerized. Under a substantial vacuum vaporization of the fatty acids will take place at temperatures lower than the temperature necessary to bring about polymerization to any desirable degree for most purthe acid value of.

poses. We have found that polymerization of the oil, where such is desirable, and the oil is of a character so as to be capable of polymerization, can be very successfully carried out simultaneously with the vaporization of the fatty acids and other impurities.

The primary object of this invention accordingly is, to provide a novel method of reducing the fatty acid content "of vegetable or animal oils and to bring said value of the 011 to the point desired for the particular use to which the oil is to be put.

A further object of the invention is to provide an'improved method or process of simultaneously polymerizing andreducing the acid value of vegetable or animal oils, by whlch both the polymerization and the reduction in acid value of the oil is effected in i a single heating of the oil.

A still-further object of the invention is to provide an improved process of removing fatty acids from animal or vegetable oils, or of reducing the acid value of such' oils by heat treatment in a closed container, in which an inert gas is utilized to expedite the evaporation of fatty acids and impurities, and to assist in maintaining a rapid movement of the vapors of fatty acids or impurities away from the oil.

The process of this invention is capable of being carried out in apparatus of various types. An apparatus, for carrying out the process is illustrated on the drawing forming a part of this application, and in which: i

The figure is a diagrammatic view of the apparatus found to be efiective for the above purposes.

The oil to be treated is placed in vacuum pans 10, being supplied thereto through a suitable conduit 11, the flow through which is controlled by a valve 12. Preferably, oil is permitted to flow into the vacuum pans 10 until the oil level therein approximates that indicated by the numeral 13, although the level in said pan may be maintained at any point desired. The bottom of the vacuum pan is connected by a conduit 14 to pump 15, to supoil from said pan thereto. The pump 15 forces the oil through a conduit 16 into a casat present preferred, I

tion 38, that is secured in understood that '11 preferably to the 17 provided with spaced heating elements 18, preferably electrically heated in well known manner. The top of the casing 17 is connected by means of a conduit 19, controlled by valve 20 to a tube 21 extending into the vacuum pan 10 and provided adjacent its end with a suitable spray nozzle to cause the oil to assume aldivided condition as it is ejected into the vacuum panunder forced circulation induced or caused by the pump 15.

Extending laterally from the pan 10 is a relatively large conduit 23 opening into a condenser 24 of tubular form or of any well known jacketed type. Cooling fluid is circulated through the jacket of the condenser 24, the fluid being supplied thereto through suitable inlet and outlet connections made at the points 25 and 26. The condensate in the condenser 24 is discharged through a pipe 25 to a receiver 26, in the form of a closed tank. The contents of the tank 26 may be discharged from time to time through an outlet pipe 27 controlled by a valve 28. The'contents of the vacuum pan 10 may be discharged through a conduit 29, controlled by a valve ing 30, when the treatment of the oil is completed as hereinafter described.

he vacuum opening closed by a cover plate 31, that is clamped to the pan by a suitable clamping means 32, in Well known manner, so as to provide a fluid-tight joint. Suitable peepholes 33 and 34 are provided through which the operation of the apparatus may be observed by the attendant.

If desired, to expedite the treatment of oil in a manner hereinafter pointed out, a conduit 35 may be provided extending to a oint 36 adjacent the bottom of the pan, so 1: at a streamof asuitable inert gas may be caused to bubble through the body of the oil under treatment, to expedite the separation of the vapors from the oil body in 'a manner hereinafter more such gas is controlled by a valve 37. The vacuum is maintained within the pan, by means of a vacuum pump of that is attached, preferably, to the pipe secany suitable manner to the tank or container 26.

The apparatus just described is at present preferred for carrying out the improved process of this application, but it will be readily other equivalent types of apparatus may be utilized to carry out the process, and that that illustrated is intended to merely an example of an'apparatus that has been found to be effective for the purpose for which it is provided.

In carrying out the process with the apparatus just described, the oil to be treated is placed in the vacuum pan through theconduit level indicated by the numeral 13. The pump 15 and the vacuum pump (not shown) are then set in operation,

pan 10 is provided with an.

fully described. The flow of any approved style, 1,

the latter serv' to create a vacuum in the pan 10, the container 26', and the condenser 24 and the connections between theseparts. The pump 15 causes the circulation of the oil from the tank 10, through the conduit 14, the pump 15, conduit 16, casing 17, conduit 19, tube 21 and nozzle 22. V In passing through the easing 17, the oil is brought into contact with the heating elements cally heated in any approved manner as above stated. If desired,,instead of utilizing elec-. tricallyheated units, heat may be applied to the oil as it passes through the casing 18 in any approved manner, as by a jacket through which the heating medium may circulate, or in any other way. The temperature of the oil passing through said casing is accordingly raised, and when the heated oil is projected into the vacuum pan 10 in the form of a spray, any vapors .that are contained therein as a result of the action of the heat to which injected stream has been subjected are separated from thedivided globules of liquid that settle gravitationally on top of the mass of oil remaining in the pan 10. The vapor thus freed is withdrawn under the action of the vacuum pump, that is continuously operated to maintain the vacuum in the pan 10 at a relatively high point. Said suction draws the vapor through the conduit 23 into the condenser 24, where the vapor is condensed and the condensate flows to the container 26.

The apparatus is that is, the oil is repeatedly circulated through the casing 17 and gradually brought to the temperature at which the impurities that it is desired to remove will vaporize, and at which the oil will be polymerized, if it is desired to polymerize the oil, at the same time that it is being subjected to the treatment to remove fatty acids and other impuri ties.

In order to further expedite the separation of the vapors from the heated body of the oil, a stream of a non-reactive or inert gas may e projected through the conduit 35 to the outlets 36 disposed adjacent the bottom of the pan. This gas bubbles through the body of oil producing violent agitation of the oil, this speeds the vaporization of the impurities in the form of fatty acids and so forth, by increasing the oil surface exposed to the action of the suction of the vacuum pump, and by causing a circulation of gas away from the body of the oil to take place, such circulation carrying with it the vapors emanating from the oil body. The vacuum will be only slightly reduced by adding such inert gas.

When a vegetable or animal oil is placed in the pan 10 and the apparatus is operated after the manner just described, it is found that, if the oil is of the type that is capable of being polymerized by heat, the oil is graduoperated continuously,.

such as the units 18,-

ally polymerized unaccompanied by oxidation. Such polymerization increases the consistency of the oil, and by it the viscosity may be brought to any desired point. At the same time, if the oil is brought to the temperature necessary to effect polymerization thereof, said temperature is sutficient to'cause vaporization of fatty acids and similar impurities that are contained in the oil. The acid values of oils rise very substantially during the polymerization process, and when the oil is treated as above described such acids are vaporized. Accordingly, as the heated oil is projected into the vacuum pan through the nozzle 22, which serves to divide the liquid portion of the oil,'causing' the vapors to be freed from the liquid or particles. The vapors are withdrawn by the action of the vacuum pump and condensed. It is clear accordingly that the apparatus serves not only to polymerize the oil, but to simultaneously remove the fatty acids-therefrom. Of course, if the oil under treatment is of the type that is incapable of being polymerized by heat, the apparatus will serve merely to withdraw the fatty acids and vaporizable impurities from the mass of oil.

Preferably the apparatus above described is constructed of Monel metal, because of the fact that-the kind of metal employed inthe equipment is liable to affect the color of the oil under treatment. It has been found that Monel metal will not cause any change in the color of the oil, when treated as above described.

As above indicated, there are many kinds of oils that are capable of being polymerized .vegetable oils, such as cottonseed oil, cocoanut oil, corn oil, and so forth.

One essential characteristic in the quality of oils is that they must be able to be heated to a temperature high enough to volati-lize fatty acids and other impurities Without breaking.

Oils that are polymerized by usual methods are high in acidity, relatively dark in color, and have the odor of fatty acids and acrolein. Polymerized oils, obtained from the practice 'of the process of this application, are. ex-

ceedingly light in color, low in acidity and free from any other odor than that of pure oil. Unpolyinerizable oils, treated so as to be very low in acidity are also free from odor, thus materially contributing to their usefulness in food products.

The process of this application has been found to be especially useful in polymerizing and reducing the acid value of linseed oil to a very low point. Polymerized linseed oil light in color and having a low acid value is extremely desirable for use in forming above described the oil is circulated and re-' circulated from the vacuum pan through the pump, the heating casing and the spray nozzle, gradually increasing the temperature and gradually withdrawing the vaporized fatty acids and other vaporizable impurities. Polymerization of linseed oil takes place in temperatures ranging from 218 to 320.C. Temperatures in excess of the maximum just given may cause the entire mass to solidify. In treating linseed oil, as in treating other oils, the pressure within the vacuum pan is reduced so that a high vacuum is maintained therein, since the more perfect the vacuum, the more rapid and complete will be the evaporation of fatty acids from the oils; The usual vacuum obtainable in practice is about 29% inches of mercury. The vacuum may, or may not, be applied while the oil is coming up to the polymerizing temperature, if the oil is. out in the vacuum pan at a temperature lower than the point just stated. If desired the application of the vacuum may be delayed until polymerization has progressed to any desired extent, although the operation is accomplished in a shorter time, if a good vacuum is maintained in the vacuum pan throughout the entire process. As soon as the oil reaches the correct temperature, which of course, depends upon the particular oil under treatment, reactions take place within the oil which increase the viscosity and simultaneously break down some of the fatty glycerides into fatty acids and other decomposition products. These vaporized fatty acids and decomposition products are drawn out by the operation of the vacuum pump in the manner above described.

The length of time during which the operation must be continued to reduce the acid value to a very low figure depends, of course,

upon the nature of the oil that is to be treated. For an extremely viscous oil, this time averages from 5 to 6 hours, assuming-that the oil is put in the pan at an ordinary temreaching an operating temperature is about oneand one-half hours.

If polymerization of the oil has been carried on to the desired extent, and the acidity of the oil so polymerized has not been reduced to the desired value, circulation may be continued at a reduced temperature just high 'perature. In this event the time required for enough to vaporize the remaining fatty acid but not to at the same time rapidly further polymerize the oil, the temperature should be maintained at 270 0., when polymerization has taken place to the desired extent, and it is desirable. to remove further fatty acids in order to bring the acid value to a lower point.

The most desirable procedure in- Carrying out the process of this invention however, is to follow the changes in acid v: lue, when the viscosity is close. to that desired, and by careful adjustment of the temperature, the oil can be made to have a satisfactory low acid value at the same time that 'it reaches the desired viscosity. The acid valuemay easily be carried down to 1.0 .or even under this value if necessary. When the oil is to be used in the manufacture of printing inks, an acid value of 2.0 or under is satisfactory. The acid value, of course, is determined in accordance with the well known practice, that is an oil has an acid value of 1, when one milligram of potassium hydroxide will neutralize one gram of oil.

If it is desired to speed up the separation of fatty acids during the polymerization of the oil, a stream of an unrcactive or inert gas may be fed into the vacuum pan, as above described. In treating linseed oil, in order to polymerize and at the same time reduce the acid value to a very low point carbon dioxide may be used as the gas, since this gas is inert when put to this use and has no effect whatever upon the operation of the process. The use of this gas reduces the total operating time to about three-fourths of the avera'gc time required to complete the operation. It should be understood that it is possible however to make a satisfactory low-acid polymerized oil without the use of carbon dioxide or any other gas. The use of this feature of the invention being optional with the operator.

The circulation pump 15 is, preferably, made large enough to keep the mass of oil turning over about once a minute. This high circulation makes it possible to heat the oil rapidly without danger of discoloration, and also reduces the amount of decomposition during the process. Although electric heat lends itself well to automatic temperature control, as well as uniform heat transfer over the entire heated surface, all of which is desirable in practicing the process of this application, it should be understood that almost any type of heater or heating means can be used.

The acid value of the oil, once the. process is initiated, bears no direct relation to the acid valueof the finished product. A highly refined oil or a clarified raw oil may be used as may be desired. The highly refined oil may have an initial acid value of 0.1 and the clarified raw oil may have an initial acid value of 6.0. Both, however, if treated as above described will result in polymerized oils of equally low acid values although, of course, the color of the finished polymerized oil is dependent upon the initial refinement of the oil that is subjected to the process. The exact procedure used for polymerizing oils of different qualities is not precisely the same, since some oil polymerizes fast, some slow, other oils polymerize at low temperaturcs, while still others require high temperatures. However, in principle, the trcatn'icnt is identically the same for all oils, the temperatures and other details being readily ascertained \vithout extended experiment. The theory of the process is believed to be as follows: The so-called animal and vegetable oils consist at least partly of glyccridcs of unsaturated fatty acids, having the propery of undergoing certain chemical changes at clevatcd temperatures, which cause a marked increase in viscosity. The chemical reactions taking place, when the oils are heated as described, are not well understood, although it is generally accepted that in some way polymerization occurs. At the temperature required for polymerization some reactions occur and volatile products are produced among which are water and acrolein. These two are easily volatilizcd without vacuum, but in addition to these, a mixture of fatty acids forms. T hcse acids have exceedingly low vapor pressure, even at 300 0., and it is therefore necessary to use special means for their removal. The apparatus above described carries out the process very effectively and gives a high ratio of vaporizing surface in proportion to the mass of oil being treated. y

The invention has been above described in considerable detail. It should be understood, however, that the invcntion is not re- 'stricted to such detail, but that the scope thereof is indicated by the following claims.

\Vhat we claim as ourinvention is:

1, .The process of simultaneously polymerizing and reducing the acid value of oils of an ester type which consists in circulating a mass of oil in a closed path heating said mass of oil during its circulation in said closed path to a. ten'iperaturc sufficientto cause polymerization of the oil and vaporization of the fatty acids contained therein; providing a body of the oil in said closed path; dividing the oil into a spray over said body of oil during its circulationaml causing finely divided particles thereof to descend upon and be deposited uinformly over substantially the entire area of the surface of said body of oil; withdrawing the vapors freed from said mass of oil by said spraying operation, and continuing the above steps until polymerization of said mass of oil is completed.

2. The process of simultaneously polymerizing and reducing the acid value of oils of an ester type which consists in circulating a mass of 011 in a closed path; heating said mass of Oil during its circulation in said closed path to a temperature suflicient to cause 'iolymcrization of the oil and vaporization of the fatty acids contained therein; providin a body of the oil in said closed path; dividing the oil into a spray over said body of oil during its circulation and causing finely divided particles thereof to be uniformly distributed over substantially the entire area of the surface of said body of oil; withdrawing the vapors freed from said mass of oil by said spraying operation, causing an upcurrent of volatile constituents in said body of oil by introducing a stream of inert gas near the bottom of said body of oil, and continuing the above steps until polymerization of said mass ofoil is completed.

In testimony whereof we afi ix our signatures.

lVOODFOR-D F. HARRISON.

AUGUSTUS H. BATGHELDER.

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