US1247782A - Process whereby neutral oils can be profitably recovered from their "foots" or soap-stock. - Google Patents

Description

UNITED STATES PATENT OFFICE.

EUGENE E. AYRES, JR., OF CHESTER, PENNSYLVANIA, ASSIGNOR TO THE SHABPIIES SPECIALTY COMPANY, OF WEST CHESTER, PENNSYLVANIA, A CORPORATION PENNSYLVANIA.

PROCESS WHEREBY NEUTRAL OILS CAN BE PROFITAIBLY RECOVERED FROM THEIR.

FOOTS OB SOAP-STOCK.

1,247,782. No Drawing.

To all whom it may concern:

Be it lmown that I, EUGENE E; Ame, J r., a citizen of the United States, residing at Chester, in the county of Delaware and State of Pennsylvania, have invented a certain new and useful Process Whereby Neutral Oils Can be Profitably Recovered from Their Foots or Soap-Stock.

My invention comprises, generally stated; first, the preliminary treatment of the foots to reduce the stability of the emulsion; second, the centrifugal separationof the treated emulsion into two portions, one (A) containing most of the neutral oil and some water and soap, the other (B) containing most of the water and soap with a little oil; and, third, the chemical treatment of the emulsion (A) discharged from the centrifuge in order to separate the oil in sufficiently neutral condition to be economically refined to neutrality.

The invention hasfor its primary object to provide a simple, efiicient and economic method of recovering the neutral oil from the soap with which it is emulsified.

In the generally practised methods of refining oils, the crude oil is treated with a solution of caustic soda. The efl'ect of this treatment is to neutralize the free fatty acids in the crude oil with the formation of soap, and to dissolve the impurities in the crude oil in the alkaline water. When the soap is precipitated in this way, a certain percent age of the neutral oil is usually emulsified and carried down with the soap and water. Heretofore this oil has not been recovered in its neutral state. The foots thus formed are sometimes sold as such to the soap makers but more often the soap emulsion is acidified to recover the fatty acids. In the latter case, the oil mixed with the fatty acids is sold simply as soap stock, as the oil cannot' be profitably recovered from the high percentages of fatty acids. In other cases, the foots.are .treated in such a way as to trecover glycerin from the oil. Where the percentage of oil in the foots is high, the

refiner of vegetable oils has suffered considerable loss heretofore. A number of attempts have been made to recover this neutral oil by centrifugal methods, but the trials have not been commercially successful be- Speclflcation of Letters latent.

Patented Nov. 2'7, 1917.

Application filed May 21, 1917. Serial No. 169,899.

cause of the high stability and the high viscosity of the emulsion.

I have found that by certain operations and reactions affecting the emulsifying agents it is possible by means of centrifugal force to separate the foots into two portions, one (A) of which will contain most of the oil, the other (B) containing most of the water and soap. Furthermore, I have found it possible to chemically break the emulsion (A) discharged from the machine because of the absence or changed character of emulsifying agents in the emulsified water.

There are, broadly speaking, two types of reactions that will affect the emulsifying agents in such a way as to reduce the stability of the emulsion. The first reaction will so change its chemical constitution that the emulsifying agents lose their property of stabilizing the emulsion. I have found that in most cases the interaction of substances already in solution will serve to foots are diluted with water. The rapidity of the reaction is hastened by the application of heat. The yield of oil recovered by such a procedure is sufliciently high in most cases for commercial profit.

But I have found that the yield of oil can be increased greatly in the majority of cases by assisting this reaction by the addition of chemical reagents. It is essential to select some reagent that will not saltthe soap out of solution and will not decompose the soap to form fatty acids. I have found that a good type of reagent for the purpose is any alkali or-alkaline salt. A convenient alkaline salt is normal sodium carbonate, which has the advantage of causing a minimum saponification 10% of neutral oil. The effect of this first reaction to alter the chemical constitution of the emulsifying agent can be noted by (1) a reduction in viscosity, (2) a tendency to separate by gravity into two layers, and (3) case of centrifugal separation.

A second reaction can be obtained which will partially or completely transpose the emulsifying agent from solution in the water to solution in the oil. I have found that the addition of any acid will reduce the solubility of the emulsifying agent in water found that boric acid has a minimum efiect h by the application of heat.

substantially as follows: The foots and increase the solubility in the oil. Ihave on the soap while it is efficacious in causing this second reaction, thereby reducing the stability of the foots emulsion. However,

if it is desired to recover the oil in its neutral state (not dissolved in fatty acids) it is essential that the soap be not decomposed.

Both of the reactions described are aided proceed from the refining kettle are diluted with from In carrying out the invention, I

one-half to two parts of water (more or less water may affect the ease of centrifugal separation) The diluted mixture is then heated, preferably to boiling, after the addition of 2% of normal sodium carbonate or 2% of boric acid. When the .sodium carbonate is used, I prefer to allow the hot liquid to.

settle for about one hour to permit a partial gravity separation, with formation of a lower layer containing very little oil,'which can be run off before centrifuging the remainder, thus reducing the volume of liquid to be handled by the centrifuge. When boric acid is used, the period of settling is of no great advantage as there will be no very distinct gravity separation. The invention should be understood as not being limited to the above proportions of the chemicals used, and, as indicated, the use of sodium carbonate or boric acid is not essential to the "preliminary treatment of the emulsion, although I- have found that the use of these reagents causes a higher yield of oil in every case and a greater uniformity of results. Heat is not essential although it is an advantage.

The next step in the process is to pass the 1 treated foots emulsion through a centrifugal separator. The lighter portion will be an oil emulsion containing}x as a rule, some 45 water and soap (emulsion The heavier portion will contain most 0 the water and soap with a little oil (emulsion B). The efficiency of the centrifugal separation is dependent upon the thoroughness of the preliminary treatment and, as indicated, the yields of 011 will-be higher when the reagents are used to affect the emulsifying agents.

The emulsion of oil and water (A) discharged from the centrifu al separator can be rendered unstable readi y by any one of Y the procedures mentioned below:

1. Salting the soap out of solution.

2. The addition of an electrolyte.

3. Freezing and remelting. Y v

4. Acidifymg with an acid suclf as sulfuric acid.

The emulsion treated in this way can then be separated either by gravity or by a centrifugal separator.

In saltmg the soap out of solution, the

tained 3% neutral oil.

While the soap can be salted out by means of substances other than common salt, I prefer the latter because of its low cost.

As a specific example of the operations and results of my invention, the following is submitted: To 100pounds of foots was added 150 pounds of water and 4 pounds of sodium carbonate in solution. The mixture was boiled for five minutes and settled one hour. Then- 73 pounds of soap solution were drawn ofl from the bottom. The liquid remaining in the tank was thoroughly mixed and passed through the centrifugal machine at the rate of 1280 pounds of water and 152 pounds of emulsion per hour. The-water run off from the tank after settling con- The water discharged from the machine contained 2.57% neutral oil. The emulsion discharged from ,the machine contained 71% neutral oil. The original soap stock contained 25%: neutral oil. The emulsion from the machine was broken by the addition of common salt andthen separated by gravity. The separated oil contained about of 1% acidity. After refining by the usualmethod, the oil was pronounced of good marketable quality.

The weight of recovered oil was 15.5 pounds. In some of my experiments, I have recovered as high as 95% of the oil originally. present in the foots. I

The above operations and results in the specific example given were with relation to the jfoots obtained from cotton seed oil obtained from the ordinary caustic soda treatment.

so as to reduce the stability of theemulsion,- and separating out the oil from the last named product.

2. In the recovery of neutral oil from foots, the process which comprises adding water to the foots and heating, subjecting the product to centrifugal action with separation of a part containing the bulk of the 011, treating said part with a chemical reagent capable of reducing the stability of the emulsifying agents found with the oil, and separating the oil from the liquid in which it is contained by means of its lower gravity. i

3. In the recovery of neutral oil from foots, the process which comprises the addition to the foots of a chemical reagent adapted for reducing the stability of the emulsifying agents, separating from the product apart containing the bulk of the oil and a part containing the bulk of the water and soap, treating the part containing the bulk of the oil with a chemical reagent adapted for breaking the emulsion, and separating oil from the latter product by means of differences in'specific ravity. 4. In the recovery of neutral oil from foots, the process which comprises the addition to the foots of water and a chemical reagent for reducing the stability of the emulsifying agents, separating from the product by means of differences 1n specific gravity 9, part containing the bulk o1 the oil, and salting the part containing the bulk of the oil,

5. In the recovery of neutral oil from foots, the process which comprises the addition to the foots of water and a chemical reagent adapted to reduce the stability of the foots emulsion and heating, separating the bulk of the soap solution and the bulk of the oil of the product by means of their difference in specific gravity, subjecting the bulk containing the oil to centrifugal action, and adding salt to the oil emulsion separated by the centrifugal action.

6. In the recovery of neutral oil from foots, the process which comprises the addition to the foots of more than half its weight in water and a chemical reagent for reducing the stability of the foots emuland separatin the bul of the soap solution from the 111k of the oil, subjecting the solution containing the bulk of the oil to centrifugal action or separation of the bulk of the water and soap from the bulk of the emulsified oil, treatin the emulsified oil with salt, and separating the oil from the salted product by gravity.

In testimony whereof I have hereunto set my name this 19th day of May, 1917.

EUGENE E. AYRES, JR.

- sion and heating, settling the heated product