US2397161A - Manufacture of soap - Google Patents

Description

March 26,` 1946. L. sl-:NDER ET AL MANUFACTURE OF SOAP Filed Nov. 25, 1945 Patented Mar. 26, 194s A UNITED MANUFACTURE F SOAP Leopold Sender, Baltimore, Md., and Leo D. J ones, I

Philadelphia, Pa., assignors to The Sharples Corporation, Philadelphia, Pa., a corporation of Delaware Application November 25, 1943,'Ser1al No. 511,707

6 Claims.

The present invention pertains to manufacture of soap by a continuous process. It is an improvement inthe prior processes described in the patents to Scott, 2,300,749 and 2,300,750.l

In the processes of the above-mentioned Scott patents, an aqueous saponifying reagent (e. g., lye) is passed continuously into confluence with a owing stream of fat and the fat is saponied by mixing of the saponifyin-g reagent therewith while maintaining the reagent mixture at an elevated temperature. From the mixing apparatus in which the saponification is accomplished, the resulting soap-containing mass is passed through a centrifugal separator which removes spent saponifying reagent from the formed soap, which has previously been grained by the addition of salt or equivalent reagent.

In practice of processes such as those described in the Scott patents, difficulty has sometimes been encountered due to formation of emulsions 0f soap in used reagent which are extremely difficult to separate. As a result'of this diillculty, it is necessary to provide centrifugal equipment of capacity in excess of that which would be required, if' such difficulties were not encountered. 'Ihe reason for necessity of such excess centrifugal capacity is that, in cases of centrifugal treatment of mixtures which are diflicult to separate into soap and aqueous phases respectively, sufflcient centrifugal capacity must be available to provide more prolonged centrifugation than would otherwise be necessary.

The present invention rests upon the discovery of an improved process by which the formation of difilcultly separable emulsions may be consistently avoided. As a result, the processes of the Scott patents, when modified to include the features of the present invention, can be uniformly operated to obtain a saponication reaction mixture Which can be readily separated centrifugally.

In the practical operation of a process such as that described in either of the Scott patents discussed above, mixing apparatus is used which provides for progressive passage of the reactionv mixture through a series of mixing compartments. These mixing compartments may be either separate compartments of a single large mixer subdivided by baiiies, or they may be in the form of a plurality of separate small mixers. In either case, the purpose of compartmentation is to insure a more thorough reaction of the fat with the saponifying reagent to cause thorough utilization of the saponifying reagent, and to obtain a higher degree of saponiflcation of the fat than would otherwise be possible. The present invention rests upon the discovery that the formation of diflicultly separable emulsions can be avoided consistently by exercising (ci. zeef-41s) care to obtain saponmcation of the fatty acm content (both free and combined) of the fat undertreatment in such amanner that the degree of saponication of the saponiable acid of the mixture in each compartment of the mixen is either .belowv 70% or above 85%.

The manner in which the `invention is practiced in certain of its more important variants is illustrated in the attached flow sheet,

in Which,

Figure 1 illustrates one embodiment of the practice of the invention, which includes a number of possible variations, V

Figure 2 illustrates a slightly modied form,

Figure 3 illustrates a still further modification, and

Figure 4 illustrates a modification in'which the saponification of the fat is maintained below '70% during the entire first stage of a counter-current process. Figure 1 ofthe drawing illustrates a process which may be used in practice of the present invention, or in practice of the inventions of either of the Scott patents referred to above, even without inclusion of the features of the present invention. As illustrated in that figure, fat from container I0 is continuously passed into confluence with an aqueous saponifying reagent which may be lye from container Il, the fat and reagent solutions being pumped into confluence in mixer I4 by pumps I2 and I3, respectively, as described in the above-mentioned Scottpatents. The fat may be pre-heated in heater I5 to bring it to a saponifying temperature before admixture with the lye, and the lye and/or brine may Ibe separately heated, during continuous flow or in their respective containers, II and 22. Brine may also be passed from container 22 by pump 23 into confluence with the fat and lye in mixer I4; in order to grain soap formed by the saponifying reaction. Alternatively, such brine may be mixed with the lye before being passed to the ,mixer I4, or brine may be passed to a subsequent compartment of the mixer I4 as discussed in the patent to Scott, 2,300,749. In this connection, it is pointed out that the present invention is not limited to any particular method or point of introduction 4of the brine solution, and that the soap'r formed by the, reactionmay be grained by 50 the addition of brine, excess saponifying reagent or other eg1ectrolyte .capableof effecting such grainin'g, before being subjected to centrifugation, jas in *either of vthe above-mentioned Scott patents.-V

55 f Asillustrated'in' each of 'the figures of the drawing, the mixer I4 .comprises a plurality of mixing compartments, the `respective compartments being numbered'y consistently-in increments. of I0 in the respective figures of the drawing. Figure 1 so of the drawing illustrates the provision of four successive compartments, I6. I'I. Il and |90! substantially equal capacity, each of these com-11 partments being provided with a coil 20 'for passage of a heat exchange iiuid which may be either 'a heating or cooling fluid, depending upon the particular conditions to be maintained as described hereinafter. The saponied mass leaving the last compartment I9 of the mixer I4 is passed to a centrifugal 2 I where it is separated into spent aqueous reagent and grained soap phases, respectively.

The present invention rests upon the discovery that, by maintaining an extent of saponiiication of the fatty acid of the fat fed to the mixer I4 which is below '10% or above 85% in each mixing compartment, the operation of separation oi the grained soap from the aqueous reagent solution may be greatly facilitated. The primary conditions affecting the extent. of saponiiication of the available fatty acid are the amount and strength of the saponiiying reagent, the degree of heat applied to effect saponification and the time interval provided for such saponification. The extent of saponiiicaton in a given compartment may be increased by an increase in the value of any one of these four factors. In practice of the present invention, the available fatty acid may be saponified to an extent above 85% in the first compartment I6 of the mixer and thereafter maintained above vthis degree of saponiflcation (this is automatic, in case no further fat is added) or the extent ofsaponification may be maintained below 70% throughout the four mixing compartments, the mixture passed through the centrifugal 2| being a mixture still containingl at least 30% of fatty acid (combined or free) available for further saponiiication. As a still further alternative, the available fatty acid may be saponified to an extent below 70% in the first mixing compartment I6 and raised to an extent above 85% in the second, third or fourth mixing compartment I1, I8 or I9, so long as care is taken to avoid production of a saponiiied mass in any one of the four mixing compartments in which saponication of available fatty acid has occurred to an extent between 7o and 85%.- Y

As noted above, control of the process to maintain one of the several conditions discussed above coming within the scope of the invention may be attained by control of any one of several factors. For example, if it is desired to effect saponification within the first mixing compartment I6 to an extent in excess of 85%, this may be attained by use of high ratio of lye to fat and by application of higher heat in the heater I and first mixing compartment I6 than would otherwise be employed. If the process is operated in this manner it may-be desirable to cool the saponified reaction mixture after it leaves compartment I6, in which case cooling uid may be applied in the coils 20 of compartments I9, I8 or I1, or any two or three of these coils.

If, instead of operating the process to attain saponiflcation in excess of 85% of the available fatty acid in compartment I6, it is operated to effect saponifcatlon of the fatty acid in this compartment to an extent below 70% and effect saponification above 70% and above 85% for the first time in a succeeding compartment (i. e., the compartment Il, I8 or I9), it may be desirable to apply heat locally in excess of the heat applied in the other compartments, in the compartment in which saponication to'an extent above 85% is first to be attained.

In discussion of Figure 1 of the drawing, we 75 have discussed the possibility of controlling the extent of saponiflcation in the respective compartments I6, I1, I8 and I9 by control of heat inv these compartments.. As noted above, the factor trated practice of a process similar in general to that of Figure 1, but in which a. mixer 24 has 'been substituted for the mixer I4, the mixer 24 containing a first compartment 26 which is substantially larger than the succeeding lcompartments `2l, 28 and 29. The use of a relatively large first compartment 26 facilitates the operation of obtaining saponication of the available fatty acid of the fat to an extent above in this first compartment. Heat exchange means may also be used in connection with the type of compartmentation illustrated in Figure 2 ofthe drawing, just as discussed above in connection with Figure 1.

Figure 3 illustrates a modification designed to facilitate obtainingsaponification below 70% in the flrst compartment 3E of the mixer 34, but

effecting sufficient saponiiication in the larger` second compartment 31 to produce a mixture of which the fatty acid has been saponified to an extent in excess of 85%. In both of Figures 2 and 3, the saponification reaction mixtures passing compartments 21, 28 and 29 on the one hand, and the compartments 38 and 39 on the other, downstream from the compartment in which saponiiication in excess of 85% is first attained, will also contain saponification reaction mixturessaponifled to an extent in excess of 85%.

As noted above in discussion of Figure 1 of the drawing, the invention may be practiced by maintaining the reaction mixture in each of the compartments of the mixer I4 in such condition that at least 30% of the available fatty acid is unsaponifled. Such an operation is lparticularly adapted to effect depletion of the saponifying reagent in the first stage of the process, a feature which is always desirable per se. if it can be attained consistently with other features of economy of. process operation. In connection with such a first stage, it is of course necessary to complete the saponication in a subsequent stage or stages. Such subsequent stages should be conducted in accordance with the principles discussed above in order to obtain a reaction mixture best adapted for subsidence separation (e. g., centrifugation) in that stage. Thus, when addiv tional saponiiication is rst effected to cause the initially available fatty acid to be saponif'led to an extent in excess of '70%, the saponifying reaction should be conducted in such a manner as to bring the degree of saponiiication to a point in excess of 85% in the very first mixer compartment in which saponiflcation inexcess of 70% first occurs. A y

Figure 4 of the drawing illustrates the application of the principle discussed in the last preceding paragraph to practice of the second stage of a process in which the steps of Figure 1 of the drawing are performed to produce a, grained soap from the first stage centrifugal containing available fatty acid from the Ainitial fat in excess of 30% of the initially available fatty acid of said fat. As illustrated in Figure 2, the mixture of soap and fat from the centrifugal 2I is mixed with a further quantity of lyel from container 40 in mixer 44, the first compartment 46 of this mixer being relatively large in order to provide ample time for saponiiication to a point in excess of 85% in iiow of the mixture through this compartment. After passing through the compartment 4B, the mixture is passed through subsequent compartments 41, 48 and 49. Thus, in each compartment of the mixer M, the reaction mixture is one in which over 85% of the initially available fatty acid (from container l) has been saponined. The graining operation may be accomplished in the mixer 44 by introduction of a quantity of saponifying reagent in excess of that necessary to complete saponification of the fat, by introduction of salt together with the lye from containerl, by separate addition of salt, or in any other suitable manner. In any case, however, the grained soap-containing mixture is passed to centrifugal 4I for separation of the grained soap mass from saponifying reagent, this saponifying reagent being preferably returned to the first stage of the process for counter-current operation.

In this application, we are claiming broadly the feature of maintaining the reaction mixtures in the various mixer compartments in suitable condition to avoid formation of diiiicultly separable emulsions. In a co-pending application, Serial No. 511,708, filed November 25, 1943, we are claiming the combination of certain of these features with an operation of addition of a further quantity of fat to assist in utilization of the saponifying reagent. l

'Ihe feature of pre-heating the fat and later cooling the reaction mixture discussed in connection with Figure l is claimed in the patent to Scott, 2,348,855, of May 16, 1944.

Various modifications are possible within the scope of the invention, and we do not therefore wish to be limited except by the scope of the following claims.

We claim:

1. In the manufacture of soap by continuous saponiflcation of' fat, graining of the resulting g soap and ,separation of grained ysoap from aqueous reagent solution by subsidence, the process comprising continuously passing a fat together with an aqueous saponifying reagent progressively through a succession of mixing compartments at a saponifying temperature, maintaining saponifying conditions in the respective compartments adapted to produce a saponified mixture in each compartment of which the proportion of the available fatty acid of the source of fat which has been saponifled is outside of the range between 70% and 85% of said available fatty acid, passing the mixture containing soap resulting from saponification of the fat, and aqueous phase, to a. zone of centrifugation and there subjecting the resulting mixture to centrifugation and thereby separating aqueous reagent from grained soap.

2. In the manufacture of soap by continuous saponification of fat, graining of the resulting soap and separation of grained soap from aqueous reagent solution by subsidence, the process comprising continuously passing a fat together with an aqueous saponifying reagent progressively through a succession of mixing compartments at a saponlfying temperature, maintaining saponifying conditions in the respective lcompartments adapted to produce in each compartment a saponiiied mixture of which the proportion of the available fatty acid of the source of fat which has been saponifled is above 85%, passing the mixture containing soap resulting fromsaponiiication of the fat, and aqueous phase, to a zone of centrifugation and there subjecting the resulting mixture to centrifugation and thereby separating aqueous reagent from grained soap.

3. In the manufacture of soap by continuous saponificatlon of fat, graining of the resulting soap and separation of grained soap from aqueous reagent solution by subsidence, the process comprising continuously passing a fat together with an aqueous saponifying reagent progressively through a succession of mixing compartments at a saponifying temperature, maintaining saponifying conditions in the respective compartments adapted to produce in each compartmentr a saponied mixture of which the proportion of@ the available fatty acid of the source of fat which,`

has been saponied is below 70%, passing the mixture containing soap resulting from saponication of the fat, and aqueous phase, to a zone of centrifugation and there subjecting the resulting mixture to centrifugation and thereby separating aqueousreagent from grained soap.

4. A process as defined in claim 1, in which the proportion of the available fatty acid of the source of fat which has been saponifled in the first compartment is below 70% of said available fatty acid, and the proportion of said available fatty acid which has been saponied in a succeeding compartment is above 5. In the manufacture of soap by multi-stage continuous saponication of fat, graining of the resulting soap and separation of grained s oap from aqueous reagent solution, the process comprising continuously passing a fat together with an aqueous saponifying reagent progressively through a succession of mixing compartments at a saponifying temperature in a first stage, maintaining saponifying conditions in the respective compartments of said first stage adapted to produce a saponified mixture of which the proportion of the available fatty acid of the source of fat which has been saponied is below 70% of said available fatty acid in the first said compartment and each succeeding compartment, separating aqueous reagent from grained soap of the resulting mixture to complete said first stage, thereafter subjecting said grained soap-containing mass separated from the first stage of treatment to further saponication to saponify further fat of said-mass in a second stage, by passing said grained soapand fat-containing mass together with an aqueous saponifying reagent progressively through a succession of mixing compartments of said second stage at a saponifying temperature, maintaining saponifylng conditions in the respective compartments of said second stage adapted to produce a saponiiled mixture of which the proportion of the available fatty acid of the source of fat which has been saponifled is outside of the range between 70% and 85% of said available fatty acid, effecting saponiflcation of said mass in said second stage to an extent above 85% of said available fatty acid before said mass leaves the last mixing compartment of said second stage, passing the mixture containing soap resulting from saponication of the fat, and aqueous phase, to a zone of centrifugation and there subjecting the. resulting mixture to centrifugation and thereby separating aqueous reagent from grained soap to complete said second stage.

6. A process as defined in claim 1, in which the available fatty acid is saponifled to an extent above 85% before the aqueous reagent is separated from the grained soap.

LEOPOLD SENDER. LEO D. JONES.

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