US2895975A - Removal of odor and color bodies in fat splitting - Google Patents

Description

July 21, 1959 A. M. IVES ET AL 2,395,975

REMOVAL OF ODOR AND COLOR BODIES m FAT SPLITTING Filed April 16, 1956 IN VEN TORS A NDREW M IVES RICH/1R0 E THOMPSON Kay/g;

ATTORNEY- I REMOVAL OF ODOR AND COLOR BODIES IN FAT SPLITTING Andrew M. Ives, Marblehead, Mass, and Richard F. Thompson, Crete, Ill.-, assignors toSwift & Company, Chicago, Ill., a corporation of Illinois Application April 16, 1956, Serial No. 578,430

4 Claims. (Cl. 260-415) The present invention relates generally to improvements in countercurrent splitting of fatty oils into fatty acids and glycerine. More particularly, this invention is concerned with a process whereby certain objectionable components, especially colorand odor-producing bodies which result from high temperature and pressure countercurrent fat splitting operations may be eliminated from a crude fatty acid product.

Recently, considerable attention has been focused on high pressure and temperature fat splitting as a means of securing high percentages of fatty acids and glycerine from fatty oils such as tallow, greases and vegetable oils. All such processes involve the use of towers through which water and fat are passed in countercurrent fashion. The water passes through the uprising fatty material, usually in the form of fine droplets. High pressure steam maintains the column at the required operating temperature. The operation proceeds Without the use of a catalyst and is capable of splittingwell over 90% of the fat when contact times of about 3 hours are employed. In order to secure such results high temperatures and pressures are necessitated. Temperatures of about 500 F. often prevail Within the tower together with pressures of over 725 pounds per square inch gauge.

Even higher temperatures and pressures are sometimes employed as they make possible more rapid splitting.

The crude glycerine-containing portion, sweet water, is removed at the bottom of the tower and is subjected to light lime treatment before being concentrated in a suitable evaporator. Between 11 and 18% of the original dilute solution remains as a glycerine of very low ash content on completion of these operations.

Purification of the fatty acid product is attended With more difficulty. Considerable water accompanies the crude product out of the tower, as well as a portion of any impurities originally introduced with the reactants. Additionally, the crude fatty acid carries with it certain impurities which are formed within the splitting tower under the influence of the extreme temperatures and pressures which prevail therein. These bodies possess objectionable colors and odors. Furthermore, there is evidence indicating that with time the crude acids will drop in free fatty acid content indicating that these bod'es have the ability to induce color and odor degradation in the fatty acid itself. In the conventional process, the crude acids emerge from the upper end of the splitting tower at a pressure of about 750 psi. gauge at about 350 F. before being charged into an atmospheric flash chamber. Here the sudden pressure release reduces their temperature to between 220 and 250 F. The crude acids may then be fed into suitable distillation equipment, for example a tray and bubble cap tower. Here the socalled light ends may be cut from the vapors by partial condensation prior to condensing the bulk of the fatty acid product. Alternatively, the crude acids may be subjected to propane refining to remove the aforementioned contaminants. In all events, it is seen that ex- States Patent tensive treatment with complex equipment is necessary before a fatty acid concentrate is obtained which is relatively free of both water and odorand color-imparting bodies. Furthermore, the time consumed between production of the fatty acid material in the tower along with the odorand color-producing bodies and the elimination of such impurities furnishes an opportunity for them to induce further reversion in the acid itself. Finally, exposure to the air in the atmospheric flash chamber results in further oxidation and rancidity" in the acid.

It is therefore an object of the invention toprovide a method facilitating the purification of the fatty acids which result from high temperature and pressure fat splitting.

Another object of the invention is to provide a method and apparatus by means of which crude fatty acids produced by high temperature and pressure fat splitting'may be shielded from color degradation and rancidity and, concurrently, foreign bodies imparting objectionable colors and tastes may be eliminated.

An additional object of this invention is to provide a process for purifying the fatty acids removed from a splitting tower without the usual distillation operation.

A further object is to secure a purified fatty acid prodnet of light color and little odor which is resistant to degradation.

Additional objects and advantages of this invention if not specifically set out will become apparent to one skilled in the art during the course of the explanation below.

It has been discovered that prior art purification methods are inadequate because they have failed to recognize the necessity for rapidly removing virtually all objectionable impurities, particularly the complex colorand odor-imparting bodies, from the crude fatty acid which results from both batch and continuous high pressure and temperature countercurrent fat splitting. By removing the offendin bodies immediately on the emergence of the crude product from the splitting unit and before any distillation or propane refining, a stable product is obtained with relative ease. Broadly, this invention comprises collecting the crude acids immediately on their passage from the splitting unit and promptly conducting them to a vacuum chamber. Here, the light ends fraction containing the water and colorand odor-producing bodies flashes off at a temperature of about 250 F. to 300 F.

A complete understanding of the invention may be gained by reference to the following description and accompanying drawing which together disclose the individual features and combinations thereof both as to the apparatus and process which constitute the essential novelty.

Referring to the drawing, the water and fat are drawn fro-m a source of supply, not shown, through lines 2 and 3, respectively, and charged into the fat splitting tower 4. The tower is kept at a suitable operating temperature by steam introduced through line 5. Glycerine is .removed from the bottom of the tower by means of line 6 through differential pressure valve 7. Line 8, equipped with another differential pressure valve 9, placed as close to tower 4 as practical, provides suitable means for conveying the fatty acids to the vacuum apparatus 10. Line 11, provided with pump 12, provides means for removing the heavier fatty acid fraction and conveying it to a suitable storage receptacle. Means also are provided, line 13 fitted with valve 14, for recycling this acid. Line 15, at the top of the vacuum chamber, provides a passage for the lighter fractions to condensing and scrubbing apparatus 16. The line 17 is connected to a vacuum producing device, not shown, capable of producing a vacuum of 28 to 29 Hg. The line 18 carries the product to pump 19 which in turn directs it to light ends cooler 20, provided with suitable coolant supplying means. Lines 21 and 22 provide means for passing the condensed and cooled light ends to storage and for recycling if desired.

In operation, fatty material is introduced through line 3 and water through line 2 into the tower 4 which is maintained at a pressure of about 750 p.s.i. gauge and a temperature of around 500 F. by means-of steam conveyed through line 5. Alternatively, pressures as high as 3,000 to 3,500 pounds and temperatures of around 600 F. may be'employed provided that the fat splitting tower is constructed to withstand the stresses produced.

In either case, the sweet water is removed through line 6 and given suitable concentrating and purification treatment. The fatty acid passes through the line 8 at the top of the tower and passes immediately into the vacuumized flash chamber 10. Differential pressure valve 9 serves to reduce the pressure as low as p.s.i. gauge. 'The fatty acid fraction, in its passage through the line, undergoes a temperature reduction to between 300 and 350 F. before it is charged into the chamber 10. A vacuum of between 26 and 29 /2 inches of mercury prevails within the chamber. The lighter fractions, the so-called light ends, are distilled or flashed off while the heavier portions of the fatty acids are conveyed by means of line 11 through pump 12 and finally to a suitable storage vessel. These heavier portions may be recycled through line 13 if necessary. The light ends pass through line 15 to vessel 16 maintained at the same degree of vacuum as the chamber 10. As cooling proceeds, some of the light ends liquefy. The products, both gaseous and liquid, pass through line 18 and are directed to the cooler 20 by pump 19. Cold water passing through cooling coils further chills and aids condensation of the gas. The liquefied light ends are passed through line 21 to storage while the still gaseous portions, if any, are recycled through line 22. It is by means of this vacuum treatment of the crude fatty acid product immediately following fat splitting that the advantages outlined above are obtained. The light fatty acid fractions containing water and the colorand odorproducing bodies are given no opportunity to adversely aflt'ect the remainder of the product, as is the case in the operations'conventionally performed following fat splitting. The acids, given only suflicient time to cool somewhat, are subjected to a vacuum with the result that the water volatilizes and in so doing exerts-a scouring action on the fat particles. Consequently, the odor and colorproducing impurities are removed simultaneously with the water. Additionally, it is obvious that some of the relatively shorter chain fatty acids, that is, those having a lower molecular weight, may be vaporized along with the water. Fatty acids having a boiling temperature of between about 250 and 300 F. at 26-29% inches of mercury are those of a higher saponification number, are color unstable and show a pronounced tendency to develop an objectionable color. Thus the product is protected against deterioration while, simultaneously, the long chain fatty acids are concentrated. The reactionproduced impurities along with their objectionable odors and colors are eliminated while the low weight short chain acids which are easily induced to deteriorate by the presence of such foreign bodies may also be removed.

Thus, it is seen that by the removal of water, colorand odor-producing impurities and the light fatty acid fractions apurified and concentrated product is obtained which resists color and odor degradation. This improved product is withdrawn from the vacuum chamber through line 11 to which is attached pump 12 and passed to a suitable storage chamber.

The term fatty acid as used in the foregoing specification and appended claims includes all monobasic organic acids, both saturated and unsaturated which are derived from hydrocarbons by the equivalent of an oxidation of a methyl group. These acids, having as few as one carbon atom (formic acid) and as many as thirtythree (psyllic acid) are characterized by their abundance in both the plant and animal kingdoms.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The process for hydrolyzing fat into fatty acids and glycerine which comprises continuously passing the fat and water in countercurrent flow in a hydrolyzing zone maintained under temperature and pressure conditions sufiiciently high to cause the fat to hydrolyze and to maintain the products in the liquid phase, immediately conducting the reaction products under substantially reduced pressure and temperature into a distillation zone maintained under a high vacuum wherein the pressure on said reaction products is quickly reduced and the lower boiling constituents thereof, including steam, and color and odor causing bodies, are flashed olf as vapors by the self-contained heat of said reaction products, and recovering from said distillation zone a liquid fraction of fatty acids of improved color, odor, and stability.

2. The process according to claim 1 wherein the vacuum in the flash zone is about 26 to 29 /2 inches of mercury.

3. In the continuous countercurrent hydrolysis of fats wherein the fat and water are passed countercurrently under liquid phase hydrolysis conditions whereby the fat is split into a fatty acid fraction and an aqueous glycerin fraction, and the fatty acid fraction separated under high temperature and pressure, the improvement which comprises promptly reducing the pressure and temperature of said fatty acid fraction, then immediately subjecting said fatty acid fraction at a temperature of about 300-350 F. to flash distillation under a high vacuum whereby the more volatile constituents thereof, including color and odor causing bodies, are vaporized, separating the vapors and recovering a liquid fraction of fatty acids of improved color and odor stability.

4. A process for the continuous countercurrent hydrolysis of fats which comprises passing the fat countercurrent to water under high temperature and pressure conditions of at least about 500 F. and 750 pounds per square inch whereby the fat is split into fatty acids and glycerin, separating the reaction products into a fatty acid fraction and a sweet water fraction, promptly reducing the temperature of said fatty acid fraction to about 300-350 F. and the pressure to near atmospheric, then immediately flash distilling said fatty acid fraction under vacuum to vaporize color and odor forming bodies, recovering a liquid fraction containing fatty acids of improved color and odor stability and recycling a portion of said liquid fraction to the flash distillation operation.

. References Cited in the file of this patent UNITED STATES PATENTS 2,156,863 Mills May 2, 1939 2,190,616 Thurman Feb. 13, 1940 2,495,071 Mills Jan. 17, 1950

Claims (1)

1. THE PROCESS FOR HYDROLYZING FAT INTO FATTY ACIDS AND GLYCERINE WHICH COMPRISES CONTINOUSLY PASSING THE FAT AND WATER IN COUNTER CURRENT FLOW IN A HYDROLYZING ZONE MFAINTAINED UNDER TEMPERATURE AND PRESSURE CONDITIONS SUFFICIENTLY HIGH TO CAUSE THE FAT TO HYDROLYZE AND TO MAINTAIN THE PRODUCTS IN THE LIQUID PHASE, IMMEDIATELY CONDUCTING THE REACTION PRODUCTS UNDER SUBSTANTIALLY REDUCED PRESSURE AND TEMPERATURE INTO A DISTILLATION ZONE MAINTAINED UNDER A HIGH VACUMUM WHEREIN THE PRESSURE ON SAID REACTION PRODUCTS IS QUICKLY REDUCED AND THE LOWER BOILING CONSTITUENTS THEREOF, INCLUDING STEAM, AND COLOR AND ODOR CAUSING BODIES, ARE FLASHED OFF AS VAPORS BY THE SELF-CONTAINED HEAT OF SAID REACTION PRODUCTS, AND RECOVERING FROM SAID DISTILLATION ZONE A LIQUID FRACTION OF FATTY ACIDS OF IMPROVED COLOR, ODOR, AND STABILITY.

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