US2596065A - Propane decolorizing - Google Patents

Description

Patented May 6, 1952 PROPANE DE COLORIZING Robert I. Brabets, Hazelcrest, Ill., assignor to Swift & Company, Chicago, 111., a corporation of Illinois No Drawing. Application December 18, 1950,

Serial No. 201,500.

Claims. 1

The present invention relates to the decolorizing of fats and fatty acids with a liquefied, normally gaseous hydrocarbon at elevated temperatures and pressures, and more particularly to a decolorizing aid for use in conjunction with the propane decolorization of low bottoms potential feed stock, such as low-grade fats and fatty acids.

The use of propane or other liquefied, normally gaseous hydrocarbons, such as ethane, propane, butane, or mixtures thereof, to remove colored impurities from fatty acids has been described in the patent to Hixson et al., No. 2,219,652. Essentially, the process comprises dissolving crude fatty acids under pressure in several volumes of'a liquefied, normally gaseous hydrocarbon maintained at elevated temperatures and pressures whereby two phases are formed-the lighter phase containing the major portion of the fatty acids and the heavier or lower phase containing the color bodies and tarry impurities from the crude acids. The upper phase is removed and the hydrocarbon separated from the fatty acid by means of distillation to produce water-white fatty acids. Preferably, the process is carried out as a continuous counter-current process for most efficient results.

It has been found that such propane or liquefied, normally gaseous hydrocarbon decolorizing processes, while very eificient when used in treating high-grade fats and fatty acids are completely unsatisfactory in effecting the decolorization of low-grade fats, greases, or fatty acids containing a fairly high percentage of unsaponifiable material, or in treating feed stock containing an insufficient amount of color bodies, foreign matter, or the like to establish a'down ward flow in the propane tower. E

It is, therefore, an object of the present in-.

vention to provide an improvement in amethod for the decolorization of low-grade fats and fatty acids.

It is a further object of the invention to provide a decolorizing aid or additive for use in conjunction with the liquefied, normally gaseous hydrocarbon decolorization of low bottoms potential feed stock.

A further object is to provide a decolorizing aid for use in conjunction with a feed stock for a propane decolorizing operation, said feed stock having insufficient foreign matter present therein to establish a downward flow in a countercurrent propane extraction tower.

An additional object of the invention is to provide a method for treating the feed stock or crude fatty materials fed into a' liquefied, normally gaseous hydrocarbon decolorizing operation whereby low-grade fats or fatty acids comprisingthe feed stock may be satisfactorily decolorized.

Additional objects, if not specifically set forth,

herein, will be readily apparent to one skilled in the art from the following detailed description of the invention:

, In the refining of fatty materials, such as animal fats, by counter-current extraction with propane or the like as described above, the residue remaining from such operation which separates out in the lower phase may be referred to as ebony fat and resembles ordinary pitch in color and consistency.

It has now been found that ebony fat, the composition of which has never been completely determined but which is known to contain a number of complex chemical compounds of unknown structure and composition, when added to lowgrade fats and fatty acids or other feed stock having a low bottoms potential prior to the treatment of such fatty materials with a liquefied, normally gaseous hydrocarbon at elevated temperatures' and pressures in a counter-current decolorizing operation, permits the production of light color products therefrom.

These starting materials, e. g. low-grade fatty acids containing a relatively high percentage of unsaponifiable material, have heretofore been considered valueless as starting materials for the production of light color fatty acids. For ex ample, a run-through of low-grade fatty acids containing about 18 per cent unsaponifiable material (representing the still pitch from double distilled fatty acids) in a counter-current propane unit, such as that described below, failed toproduce either a bottom fraction or a lighter colored overhead even at extreme conditions.

However, when this low-grade feed stock was blended with varying proportions of ebony fat obtained from the decolorizing of tallow and subjected to counter-current propane decolorizing a light colored product was obtained.

The following table illustrates the statement made in the preceding paragraph, and is inserted for purposes of illustration only and not as imposing .any limitation on the scope of the instant invention:

The fatty acid feed stock used in the above runs wasthe same as that referred to previously, i. e. containing about 18 per cent unsaponi- 26 vials of solution of various inorganic salts.

The color of the fat is determined by comparison with the various vials until the nearest match is obtained. These standards are divided into five series: numbers 1-9, inclusive, relate to lightcolored fats; 11, 11A, 11B, and 11C relate to very yellow fats; 13-19, inclusive, relate to dark, reddish fats; 21-29, inclusive, relate to greenish fats; and 31-45, inclusive, relate to very dark fats.

It may be seen, therefore, that the very dark ebony fat having an FAC color DT 45, when propane decolorized produced a product having a dark reddish to green c0101. The low-grade fatty acids, also having an FAC color of DT 45, when propane decolorized showed no change-it being impossible, as aforesaid, to obtain either a bottom fraction or an overhead fraction with this material. However, when these two materials are blended together and propane decolorized, the resulting products for all blends, from a ratio of 0.02 parts by weight ebony fat to 0.98parts by weight fatty acid to a ratio of 0.9 parts ebony fat to 0.1 parts fatty acid, were in the very light yellow range of color, a definite improvement over the color obtained by propane decolorizing, either material separately.

The present invention, relating as it does primarily to the treatment of feed stock prior to de colorization, is not intended to cover any particular variation of the known propane or other liquefied, normally gaseous hydrocarbon decolorizing process conditions of operation. However, for purposes of illustration, the following brief description of a decolorizing unit of this type It will be readily apparent to one skilled in the artthat this may be done on either a batch or a continuous basis. This feed, mixed with the ebony fat, is then pumped into the top of a heated pressure column wherein it passes downwardly in counter-current relationship with propane or some other liquefied, normally gaseous hydrocarbon, such as ethane, butane, pentane, hexane, or the like, which has been introduced near the bottom of the tower. Sufficient hydrocarbon is introduced to bring the ratio of hydrocarbon to oil (feed stock) in the tower to about 10: 1 to 30:1 byvolume. The tower is operated at temperatures from about 190 'F. to 215 F. and under pressuresof about 550 to 700 p. s. i. 'Under these conditions,. the propane or otherliquefied, normally gaseous hydrocarbon solvent selectively dissolvesthe desired fatty material in one phase while leaving the undesirable color bodies out of solution .in another phase. The heavier phase, or bottoms, comprising oxidized fatty material, color bodies, and other impurities, together with a small proportion of solvent is withdrawn from the tower and the solvent is recovered by raising the temperature to about 220-2=l0 F. and flashing offthe propane at 250-350 p. s. i. The overhead light-colored phase is simultaneously withdrawn and the solvent recovered therefrom by passage through low pressure flash towers and vacuum strippers. As indicated by Table I above, the addition of the additive ebony fat to a low bottomspotential feed stock permits separation of a desirable lightcolor product while the same treatment'of such feed stock without the additive fails to produce either a bottom fraction or a light-colored overhead even at extreme operating conditions.

The followin table illustrates typical conditions under which the present invention may be carried out and the results attained thereby:

TABLE II Temperatures Per Pro ane Product v to 11) P165 if 011 Product Mid Top Ratio sure 00101 Fee Feed Tower Tower toms A. Low-grade fatty acid (18% un- "F. F. F. T. p. s. i.

saponifiable) 210 210 210 r 210 10:1 700 0 DT B. Product A: ebony fat (rat1o 0.9:0.1). i. 205 205 V 205 205 20:1 675 4 11 D C. S aric Acid 210 210 210 210 2011 700 0 DT 45 D. Product 0: ebony fat (ratio is set forth, showing the manner in which the In the above'examples products A and C would present invention is applied to improve the results attained in such a unit:

The feed stock to which the present invention is primarily applicable is one having a low bottoms potential or, in other words, any feed stock which in itself does not contain enough color bodies, foreign matter, etc., to establish a downward flow in the propane tower. As mentioned above, one of the most important applications of the invention is the treatment of low-grade fats and fatty acids having a relatively high un saponifiable content. To this feed stock, before or after heating,i is added a small amount. of

not decolorize alone under any conditions of operation.

The ebony fat should be added to the stock before it is fedto the propane unit. It should be uniformly blended into the stock, either by agitation or by circulation'with pumps. In case one run-through of the treated product does not effect sufiicient decolorizing, or too large a production of bottoms is necessary to obtain the desired overhead color, the high bottom fraction produced may be recycled through the propane unit again and satisfactory results should thus be obtained.

1 Asa means of insuring against adversely affecting the overhead specifications, (iodine number, free fatty acid content, titer and the therefore, be seen that the ebony fat obtained from a run-through of a product treated in accordance with this invention may in turn be used as an additive for further runs of the same or similar product.

By the term low bottoms potential as used in the foregoing specification and appended claims is meant a small capacity in a feed stock to produce bottoms upon the subjection of said feed stock to propane decolorization, i. e. a high unsaponifiable and free fatty acid content and/or a low color body--foreign matter content insufficient to establish downward flow in a countercurrent liquefied, normally gaseous hydrocarbon decolorizing column.

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.

I claim:

1. In the decolorization of low bottoms potential fat and fatty acid feed stock by treatment thereof with a liquefied, normally gaseous hydrocarbon under conditions of elevated temperatures and pressures, the step which comprises incorporating ebony fat in said low bottoms potential feed stock prior to decolorization thereof.

2. In the decolorization of low bottoms potential fat and fatty acid feed stocks by treatment thereof with a liquefied, normally gaseous hydrocarbon under conditions of elevated temperatures and pressures, the step which comprises admixing ebony fat with said low bottoms potential feed stocks in an ebony fat to feed stock ratio of from about .02:.98 to 0.9:0.1.

3. A method of decolorizing low bottoms potential fat and fatty acid feed stocks, which comprises adding thereto ebony fat in at least an ebony fat to feed stock ratio of from about 0.02:.98 and thereafter subjecting the feed stock plus ebony fat to treatment with a liquefied, normally gaseous hydrocarbon under conditions of elevated temperatures and pressures.

4. In the decolorization of low-grade fats and fatty acids by treatment witha liquefied, normally gaseous hydrocarbon, under conditions of elevated temperatures and pressures, the step which comprises adding to said low-grade fats and fatty acids ebony fat obtained from a similar fat or fatty acid in at least an ebony fat to low grade fat and fatty acid ratio of about .02:.98.

5. A method as in claim 4 wherein the ebony fat-low-grade fat and fatty acid ratio ranges from about .02:.98 to 0.9:0.1.

ROBERT I. BRABETS.

No references cited.

Claims (1)

1. IN THE DECOLORIZATION OF LOW BOTTOMS POTENTIAL FAT AND FATTY ACID FEED STOCK BY TREATMENT THEREOF WITH A LIQUEFIED, NORMALLY GASEOUS HYDROCARBON UNDER CONDITIONS OF ELEVATED TEMPERATURES AND PRESSURES, THE STEP WHICH COMPRISES INCORPORATING EBONY FAT IN SAID LOW BOTTOMS POTENTIAL FEED STOCK PRIOR TO DECOLORIZATION THEREOF.