US2283776A - Process of making soap - Google Patents

Description

May 19, 1942. B. H. THURMAN PROCESS o'F MAKING soAP Filed March 5, 1958 SWX/Maga Patented May i9, w42

Pit/@GES @F 59th? Benjamin. Tihurmsn, Escamilla, hl.. to Benning, Enc., llt/eno, Neve, a

Nevada Application March d, lutti, Seri-.ai lilo,o m42-2d i 3 tliaims.

soda, have heen employed in relatively dilute concentration, as compared to those con templatecl hy the present invention, for saponiiy-n materials such as glycerides, fatty acids,`

alocdic acids, and. higher fatty acid esters of higher fatty alcohols such as, for example, sperm oil. Such materials have ordinarily been saponii'led hy the conventional batch process in large open soap making kettles. The* temperature which could be employed was not greatly in excess of the boiling point of Water. Thus relatively dilute solutions of akalies were necessarily employed in order to provide sufficient water to maintain the soap in iluid condition, Even with soap making processes employing closed kettles, caustic soda solutions above 50% caustic soda content have 4not heen employed, as this amount of caustic soda is approximately all that can be dissolved in Water at ordinary temperatures.. The present invention is directed to a process oi. making soap in which caustic soda solutions sub.. stantially above 50% concentration and ranging: up to concentrations of 85% to 95% are employed. A large portion of known. soap making processes is concerned with removingwater from the soap produced, and all of such processes involve heating large quantities of water present during the saponication reaction, thus wasting large amounts of heat. According to the present invention, concentrated caustic alkali solutions (materially above 50% concentration) are employed, lthus reducing the amount of material which must be heated, and also reducing the amount of water which must be separated from the soap. The present invention finds its chief utility in a process in which glycerine or other volatile materials such as higher fatty alcohols which caustic alkali solutions in concentrations substantially above 50% are employed.

Another object of the invention is to provide a process of producing soap and recovering volatile materials liberated in the process in which the amount of water evaporated and condensed is markedly reduced.

A further object of the invention is to provide a continuous process of producing soap in which concentrated solutions of saponifying alkali are continuously mixed with the saponiilable material under high temperature conditions.

A still further object of the invention is to provide a process of saponifying glycerides of fatty acids and directly recovering-relatively concentrated glycerine.

Other objects of the invention will appear in the following description of the preferred embodiment thereof. This description is given in connection with the attached drawing, which diagrammatically shows an apparatus capable of carrying out the present invention.

Referring more particularly to the drawing, i0 indicates a source of supply, such as a tank,- for the saponiilable material; H indicates a heating device for preheating the saponiiiable material -before admixture with the saponifying materials; i2 indicates a device for forming concentrated solutions -of alkali; i3 indicates in general a proportioning and mixing system for continuously mixing the preheated saponifiahle material and alkali; I4 and I5 indicate heating devices for the resulting mixture; i6 indicates a vapor separating chamber for separating volatile materials from the soap; ll indicates in general a condenser system for condensing such volatile materials and maintaining a vacuum in the vapor, separating chamber I6; and I8 indicates a conveyor for removing soap from the vapor separating chamber without breaking the vacuum and cooling the soap.

The tank i0 for the saponiiable material may include a heating coil or other' heating device I9 for rendering the saponiable material lowable, if necessary. It is preferred not to heat such material in large amounts and in contact with the atmosphere to temperatures much above that necessary for enabling the same to be pumped. A pump 20 may be provided for withdrawing saponflable material from the tank I0 and forcing the same through the heating device Il, which may include a heating coil 2i and a burner 22 for liquid or gaseous fuel.

The device for forming concentrated solutions of alkali may include one or more receptacles 23 provided with heating jackets 24, or other heating means, in order to heat materials contained therein. Provision is made for circulating any desired heating medium, such as steam or heated mineral oil, through the Jackets -24 by means o'f pipes 2l and 23. The receptacles 23 are preferably closed and capable of sustaining substantial internal pressure, but in certain modifications ofthe present process, open vessels may be employed. `Water may be introduced into the receptacles 23 through pipes 21, and, likewise, alkali may be introduced in measured amounts through removable closure members 28. Each receptacle 23 is also provided with an agitator 29, which may be driven from any suitable source of power through a pulley 30. By mixing the alkali, such as caustic soda, with water under high temperature conditions, and preferably under pressure to prevent evaporation of the water, extremely strong iluid solutions of alkali may be produced. For example, caustic soda solutions ranging from substantially above 50% caustic soda to solutions containing only a small percentage of water may be prepared.

For a continuous process. the receptacles 23 may be employed alternatively to deliver material to the process from one of the receptacles while a solution is being prepared in the other receptacle. Thus, by opening the valve 3i inthe pipe 32 and closing the valve 33 in the pipe 34, a solution oi the desired concentration may be pumped from one of the receptacles by a pumpY v:maarre reaction and also to increase the temperature o f the mixture during iiow, if necessary, to cause said substantially complete reaction and maintain the resultant soap in liquid form. Preferably, this temperature is suillciently high to cause the soap to be in molten form when anhydrous, after water and other vaporizable materials have been removed from the soap in the vapor separating chamber Il. The pressure and temperature in at least the latter heating device l5 are also desirably adjusted to cause all, or a substantial part, of the vaporizable materials to be in vapor form when delivered into the terial from the heating coil 3l may be delivered to the proportioning pump 31. 'I'he proportioning pumps 36 and 31 may be driven by a variable speed motor 33 and a `variable speed device 39 may be interposed between said pumps, so that desired amourits and proportions of saponifiable material and alkali may be delivered to the mixer 40. The particular proportioning apparatus shown is merely by way of example. and any other type of proportioning apparatus capable of delivering accurately proportioned streams to the mixer 40 may be substituted therefor. Also, in practicing the process, the heating device Il may be positioned between the proportioning pump 31 and the mixer 40 instead of the position shown. Also a similar heating device for the alkali solution may be employed either before or alter the proportioning pump 38, if it is desired to prepare the alkali solution at a temperature below that at which it is delivered to the mixer 40.

The mixer 40 is preferably a flow mixer of any suitable type which will thoroughly admix the stream of saponiiiable material and alkali.l

It is usually suflicient to merely inject' a stream of one material at right angles into a floating stream of the other, but the mixer disclosed in the copending application of Beniamin H. Thurman, Serial No. 190,673 filed February 15, 1938, and entitled Proportioning apparatus, has been found to be extremely eillcient, and is preferred. The resultant mixture may be forced by a pump 4i through the heating device i4, which may include a heating coil 42 and a burner 22. Preferably one or more additional heating devices i5 also including a coil 42 and burner 22 are provided with an associated pump 43 for forcing the -mixture through the heating coil 42.

The heating devices i4 and i5 are employed to give suillcient time for substantially complete vapor separating chamber I6.

lThe mixture from the heating device i5 is preferably discharged against the wall M of the vapor separating chamber by nozzles 45 positioned adjacent the `wall 44. The wall 44 is maintained at a temperature above the melting point of the substantially anhydrous soap produced by means of a heating jacket 46 surrounding the vapor separating chamber IB, and

through which any desired heating medium, such as heated mineral oil, may be circulated by pipes 41 and 4l. By thus maintaining the temperature of the wall 44 above the melting point of thel anhydrous soap, the soap will ilow down the wall 44 in thin films, thus effecting the liberatinz of vapors entrained in the soap and formed in the vapor separating chamber I6. A substantially unlmpeded path for the vapors is thus provided inwardly and upwardly through the vapor separating chamber to the vapor withdrawal pipe 43 through which vapors are delivered to the condenser 50 forming paril of the condensing system il. The condensed Vaporizable material is collected in a receiver 5i, from which it may be withdrawn through a pipe 52 by any suitable means such as a pump (not shown). A vacuum pump 53 connected to the receiver 5i is provided for maintaining a vacuum in the vapor separating chamber i6 and condensing system il. I

Molten anhydrous soap iiows down the wall 44 of the vapor separating chamber I6 into the casing 54 oi the conveyor i3 and is continuously removed from the vapor separating chamber. The conveyor I8 is preferably provided with a cooling jacket 55 forl cooling the soap withdrawn from the evaporating chamber. A series of one or more additional conveyors (not shown), connected to the conveyor il, may he employed for further cooling, as disclosed in the copending application of Benjamin Clayton and Benjamin H. Thurman, Serial No. 119,168, tiled January 5, 1937. The vapor separating chamber and conveyor system employed in'the present invention may be the same as the apparatus disclosed in said application.

As before stated, a 50% sodium'hydroxide solution is substantially the greatest concentration that can be prepared at ordinary temperatures;

that is, approximately 100 parts of caustic soda can be dissolved in parts of water at 68 F., whereas 347 parts of caustic soda can be dissolved in a like amount of water at 212 F. to produce a solution of approximately 78% concentration. By mixing under pressure, extremely large amounts of caustic soda can be thus dissolved, and solutions containing only, for example, 5 to 10% water can be prepared. By mixing a stream of such concentrated caustic soda heated to a temperature of, for example, 200 F. to 500 F.. depending upon the saponiiiable material employed, with a stream of glycerides of fatty acids,

i mixture.

@,@id fatty acid esters, or other saponiflable materiai By increasing the length of the heating devices i6 or Iii and thus the length of time the materials are subjected to high temperatures.

. the Varrentrapp reaction may be obtained to any desired extent. This reaction involves the cornbination of caustic alkali with unsaturated fatty acid radicals to liberate hydrogen and produce heat. Thesame is true when employing higher fatty acid esters of higher fatty acid alcohols, such as sperm oil, in which case vaporization of higher fatty alcohols liberated requires additional heat. Also, some time of reaction is usually required with such materials, and heating devices such as I4 or I5 provide time for the completion of the reaction. l

When saponifying fatty acids, the reaction is almost instantaneous, and the temperature of mixing must be sufficient to form a fluid soap Thus the alkali solution mustusually be preheated to at least 400 F. and the saponifiable material preheated to the temperature above given, such that the temperature oi' mixing is .between approximately 400 F. and 600 F. As water is substantially the only thing to be vaorized, the material can be delivered directly to the vapor separating chamber, and the heating devices I4 and I5 omitted. Commercial bar or powdered soaps contain from 10% to 30% water, and, by adjusting the water content of the concentrated alkali solution when saponifying substantially pure fatty acids, the resulting mixture may be delivered directly to the' conveyor I8, or other cooling device, to directly produce a soap having the requisite amount of water for such bar or powdered soap. Thus, a bar of soap may be extruded directly from the conveyor system and cut in to bars or otherwise treated to produce soap in condition to be directly marketed as a detergent'.

If it is desired to render the soap anhydrous, o1' recover glycerine or higher fatty alcohols liberated in the process, the mixture of soap and volatile materials should be delivered to the vapor separating chamber at a temperature between approximating 450 F. and @0 F., depending upon the type of material being-saponiiied. That is, the mixture should he sufdciently hot that the soap is produced in molten anhydrous form after-the volatiles have been removed. It is also desirable to maintain a sui'iiciently low pressure in at least the last heating device it to cause the vaporizable material to he partly, or all, in vapor formvwhen discharged into the vapor separating chamber. Thus, -pressures as lotv as to 100 pounds per square inch can he employed in the latter part of the heating device. ilince the temperature throughout the portion ci the system in which saponifiable materials andcaustic are in contact or soap is present, is sufhciently high to render the materials liquid, relatively low pressures, for example 150 to 300 pounds per square inch, can be utilized, even in the entrance portions of the heating devices. Ii viscous mixtures are encountered, the addition of small fatty acid radicals of less unsaturation and having a smaller number of carbon atoms than the Voriginal unsaturated fatty acid radicals. Thus a more stable and harder soap can be produced. The presence of water in the system, however, retards this reaction as compared to that which would'be obtained in an anhydrous system. The materials in the process are maintained out of contact with the air when at high temperatures, and are maintained in suiicient motion to prevent local overheating with resultant pyrolytic decomposition, such that the soap or other fatty materials are not damaged.

While the preferred embodiments of this invention are disclosed herein, it is understood that the details thereof may be varied within the scope of the following claims.

l: claim as my invention:

l. 'Ihe process oi making soap and recovering concentrated glycerine directly therefrom, which comprises, mixinga stream of saponiable material consisting essentially of glycerides of fatty acids with a stream of alkali solution containing substantially in excess of 50% of alkali, preheating said l.stream ci saponiilable material to a temperature between approximately 400 F. and 620 F. before admixture with said alkali solution, preheating said alkali solution to a temperature between approximately 200 F. and 500 F. before admixing the same with said saponifiable material, adding suicient additional heat to a owing stream of said mixture to substanamounts of inert liquids, such as kerosene, can

tiaily completely react said alkali and said saponable material to form soap and liberate glycerine, thereafter discharging the resulting mixture containing soap and glycerine into a vapor separating acne while at a temperature above the melting point ofsaid soap when anhydrous,

withdrawing and condensing glycerine vapors from said zone at a rate sufficient to maintain a vacuum in said zone, and continuously removing soap from said zone without breaking said vacuum.

2. The process omakng soap, which comprises, mixing a stream oi saponiflable material with' a stream of alkali solution containing substantially in excess of 50% of alkali, preheating said stream of saponiiiable material to a temperature between approximately 400 and 620 F. before admisture with said alkali solution, preheating said alkali solution to a temperature between appronimately 200 and 500 F. before admixing the same with said saponiabie material, adding sucient additional heat to a flowing stream of the resulting mixture to substantially completely reactsaid saponiflable material and alkali to iorm soap, thereafter discharging the resulting mixture containing soap and vaporizable material into a vapor separating zone while vat a temperature above the melting point of said soap when anhydrous, withdrawing and condensing vapors ci vaporizable material from said zone at a rate suiclent to maintain a vacuum in said zone and continuously removing soap from said zone without breaking said vacuum.

3. The process of making soap, which comprises. mixing a stream' of saponiable material consisting essentially of fatty acids with a stream saponii'lable material while in a owing stream to form soap, thereafter discharging the resulting mixture into a vapor separating zone while at a temperature above the melting point of said soap when anhydrous, withdrawing and condensv ing vapors from said mue at a rate sufficient to maintain a vacuum in said zone, and continuously removing soap from said zone without breaking said vacuum.

BENJAMIN H. THURMAN.

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