US2380650A - Continuous saponification process - Google Patents

Description

July 31, 1945.

J. J. JACOBS CONTINUOUS SAPONIFICATION Filed Aug. 1'7, 1940 PROCESS 2 Sheets-Sheet l INVENTOR JOSEPH JOHN JACOBS July 31,1945. J JACOBS I 2,380,650

CONTINUOUS SAPONIFICATION PROCESS F iled Aug. 17, 1940 2 Sheets-Sheet 2 INVENTOR JOSEPH JOHN JACOBS ATTORN -Patented July 31, 1945 CONTINUOUS SAPONIFICATION PROCESS Joseph John Jacobs, New York, N. Y., auignor to Autoxygen, Inc., New

or New York York, N. Y., a corporation Application August 17, 1940, Serial No. 853,080

SClaims.

This invention relatesto saponiflcation and particularly to a continuous saponiiication process whereby certain desired products of saponiflcation are continuously obtained.

One of the objects of the invention is to provide a continuous saponiflcation process which may be used for manufacturing soap and which,

is quicker and less expensive than processes heretofore used.

Another object is to provide a continuous process for the manufacture of soap by means oi which a desired amount of certain substances, not produced by saponificaticn may be incorporated in the finished product.

Another object of the invention is to provide a continuous process for making naphtha soap,

' which has a fewer number of steps than processes Another object of the invention is to produce a stable anhydrous lubricating grease containing between 60% and 90% soap.

Another object of the invention is to provide a process of manufacturing partial saponiilcation products such as glycerine monoor di-stearate r mono or di-oleate. 1

A further object is to provide an apparatus in which the above processes may be cflectively carried out. p

The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others. the apparatus embodying features of construction. combinations and arrangement of parts, adapted to eflect such steps, and the products which possess the characteristics, properties, and relation of elements, all as exemplified in the detailed disclosure hereinafter set forth and the scope'of' theigrsiplication of which will be indicated in the c a For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

one form of apparatus for carrying on the process of the inventio Fig. 2 is a diagrammatical representation of a modified form of the apparatus of Fig. 1; and

Fig. 3 is a diagrammatical representation of an alternative form of part of the apparatus of Fig. 2. Y

Broadly the invention comprises heating saponiflable material and certain anhydrous alkalis at relatively high temperatures in the presence of a diluent, then suddenly reducing the pressure on the mass to permit substantially instantaneous evaporation of the diluent together with certain volatile products of the saponiflcation process, removing the vapors, and collecting and removing the solid matter thus produced. The evaporation takes place according to the principle of partial pressure distillation which permits evaporation of the diluent and other volatile substances at a lower temperature than would normally be required. The process is made continuous by continuously spraying the hot saponifled mixture into an atmosphere of reduced pressure whereby the volatile matter is flashed of! and continuously removed; and the solid material is also removed in a continuous manner. I The saponifying reagent may be any alkali used in the soap making industry to "produce saponiflcation of fats. oils and waxes. Sodium or potassium hydroxide are most commonly used, and I prefer to use the anhydrous product.

The diluent used in the process may be any substance which is substantially inert to the reactants and the products of saponiiication, which is immiscible with water and the hydroxy component of the reaction products, which boils at a temperature or less than 300 C. at the dis charging pressure and which forms a constant boiling mixture with the volatile constituent or constituents of the products of reaction. Among such materials are kerosene, gas oil. paraflln oil,

paraiiin wax, high boiling white mineral oils, and

diphenyl. Kerosene has been found particularly tainers are connected by means of pipes l3 and It to amain pipe l6 leading to a spray chamber Fig. 1 is a diagrammatic-a1 representation of It. Pipes l3, l4. and II areprovided with valves i1, i8. and. i0, respectively, to control the now of material therethrough. The containers or saponiiying kettles l and ii are each provided with heating means, which may be in the form of a hollow sheath 2!! through which high pressure steam, flue gases, Dowthern." hot oil. or other heating medium may be passed in the direction of the arrows by means of the inlet and outlet connections 2| and 22. These containers are open to the atmosphere, but are provided with reflux condensers 28 to condense and return any or the material which may vaporize in the saponifying kettles. The reflux condensers are cooled by passing a suitable cooling medium through the pipes 26 and sheaths 2b.

The pipe is terminates in a spray nozzle 26 within the chamber it, so that the solution coming out of the nozzle will be very finely divided. The chamber is is provided at its upper end with a large outlet pipe 2? which leads directly to a condenser 28 of any suitable type. provided with a cooling means, as, iorinstance, water circulation pipes 28, so that vapors passing up through the pipe 27 are condensed in the condenser 28. A pipe 30 leads from the lowermost point of the condenser 28 to a container 88 which is provided' to collect the distillate. I preferably desire to maintain a vacuum in the chamber it, and forv this purpose I connect the top of the condenser 28 with a surge t lit and a steam jet ejector 38 by means of the pipe 36..

In some cases I may wish to heat the spray chamber i8, and for this purpose the chamber is provided with a sheath 3B5 having et and outlet ducts to and ill for leading; a suitable heating medium, such as one or those mentioned above,

into and out oi the sheath.

a pipe 88 is connected to the container 80 at a point about one .1. of the distance down from the top thereof, and this pipe is long enough to provide a barometric led to balance the reduced pressure within the container iii, so as to draw ofi any liquid above the level oi the connection oi the pipe with the container. Another pim 89 is connected to the bottom oi the container 8i, and is provided with an upwardly entending loop ed, the uppermost part of which is slightly below the connection or the pipe 38 with the container 239. The uppermost part of the loop to is provided with a vent pipe oi which leads up to the condenser 28, and the pipe 3&3 is also provided with a vent pipe or whici-i leads to the condenser, so that liquid can now out of the container iii through the pipe 38 when the level of the liquid reaches the connection of that pipe with the container, and through the pipe lid when the level of the liquid rises to such a point that the weight is-scient to balance the colof liquid,in the loop or.

The lower end oi the chamber it is provided with conical walls, so that solid particles food in the chamber will move downwly towards the outlet to at the bottom thereof, beneath which is disposed a screw conveyor so driven by a suitable motor to. The arrange-'2 is such that solid tter in the conveyor is will act as gesegaal to maintain the vacu in the aw;

In the operation oi this apparatus for the continuous production or soap, any suitable sanihable materials y be placed in one of the con are it or ii, say the container id, together wi a suitable oi an circus saponi- 2 agent which to be one oi those men- The valve ii is .1

' desired amount of saponiiication has taken place.

During this time there is no loss by evaporation. of any of the materials in the container since any vapor which is formed therein passes up into the reflux condenser as and is condensed and returned to the'container.

The amount or the diluent is variable and de- I pends on the particular diluent used and whether or not it is desired to remove all of the glycerine.v The amount can be calculated in accordance with the principle oiv partial pressure distill'ation so that all or,only a portion 01 the glycerine is removed with the diluent when sprayed into the spray chamber. Kerosene with a boiling range between 220 C. and280 C may be used in equal proportions with the Eat to remove substantially all oithe glycerine. In general, the higher the boiling point of the diluent, the less will be needed.

The diluent, however, another important function: it serves to transmit heat uniformly to all parts of the mixture during saponiflca tion, thus promoting homogeneous reaction and preventing overheating at localized points which might cause charring of the soap. The fat dis= solves in the diluent, and every molecule of fat is thus in close proximity with the heat-trans-= mitting diluent.

When sumcient saponiilcation has been pro= duced in the container id, the valves iii and it} are opened, permitting the mixture to how through the pipe 65 and be sprayed into the cber it from the nozzle 28. The material delivered to the nozzle consists of a fluid gel of soap in the diluent with slycerine in suspension.

Since the glycerine and the diluent are mixed together in this fluid gel as it is sprayed from. the nozzle, the boiling point of the mixture will be lower than the boiling point of either oi the materials. This is because of the principle of partial pressure distillation, the vapor pressure of both materials combining toovercome the on ternal pressure. As each small particle oi the liquid leaves the nozzle, therefore, distillation occurs substantially instantaneously, causing the glycerlne and diluent to dash into vapor which passes out through the outlet pipe 2? oi the chamber it and into the condenser til where condensation takes place. At the so time the solid soap particles precipitate out and fall to the bottom of the chamber it where they pass into the screw conveyor at, from which they I'll; be delivered to suitable molds or packaging apparatus.

'Thedistillate which collects-in the container 36 will be glycerine and the diluent. Since the diluent is lighter than the glycerlne it will rise to the top; hence the diluent will be drawn of! through the pipe 58, while the glyccrine will be ,drawn ofi through the pipe it. Before any liquid will flow through the pipe 89 the head of the lighter diluent above the glycerine, the height of the loop M is slightly less the height 0! the liquid in the container 3 l,'as maintained'by the level of the outlet thereof through pipe 38. As the liquid continuously collects in the container 3|, it is continuously separated into the diluent and the glycerine and the two are continuously dra'wn off through pipes 38 and 39,

the barometric legs being necessary in these pipes to permit the weight of liquid therein to overcome the effect of the vacuum in the condenser 28. I

While the spray chamber [6 has been described as being under a vacuum, it may, in some instances, be maintained at atmospheric pressure, or even at super-atmospheric pressure, depending upon conditions in the saponification kettle. If the saponification kettle is operated under pressure, (and it may be so operated, if desired), the spray chamber can be operated at atmospheric or even higher than atmospheric pressure, provided the sensible heat drop between the saponification kettle and the spray chamber is enough to supply the latent heat necessary to vaporize the volatile materials from the soap.

Ordinarily, however, the'saponification kettle is operated at atmospheric pressure and the spray chamber under vacuum. The temperature of the spray chamber is maintained at approximately size to maintain a low vapor velocity and so prevent soap particles from being carried out with the vapor.

Under certain conditions I may desire to eliminate the two saponification kettles I and II and provide an apparatus by means of which the materials for the process may be fed continuously into the apparatus without the necessity of alternately filling and emptying the saponifying kettles, as in the apparatus of Fig. 1. To this end the apparatus of Fig. 2 may be employed. Here the spray chamber i6, conveyor 44, condenser 28, and container 3|, with the associated pipes and connections, are the same as shown in Fig. 1. However, in this case the saponifying materials are fed through a long reaction tube 50 which may be mounted at its ends for rotation and provided with suitable rotating means as for instance an electric motor 5|. The tube 50 is preferably mounted at a slight angle to the horizontal so that materials fed into the upper end will gradually pass towards the lower end as the tube is rotated. Means is provided to heat the tube 50, and to this end a casing 52 is shownsurround-' ing the tube 50, and is provided with inlet and outlet connections 53, so that a heating medium,

I such as one of the materials mentioned above,

' might be passed through it.

the boiling point of the mixture of the glycerine and the diluent under the given vacuum. Usually this temperature will be maintained from the mixture without additional heat. However, if necessary the chamber Hi can be heated by means of the sheath through which the heating medium is circulated. If there is not enough sensible heat drop available between the saponification kettle and the spray chamber, a temperature higher than the boiling point of the mixture may be maintained in the spray chamber, causing heat to flow from the heating medium to vaporize the mixture of diluent and glycerine from the soap.

The saponifying kettles Ill and H are operated alternately. When one is discharging into the spray chamber IS, the otheris being filled and heated to carry on the saponifying process, and by the time the first is empty, saponification has been sufficiently carried on in the second, so that the valves for the second may be opened and those of the first closed, to permit the saponified mixture to flow out of the second kettleand the first kettle to be loaded again for repetition of the aforementioned treatment.

With the arrangement described above, solid soap-particles entirely free, if desired, from glycerine and the diluent are continuously delivered from the conveyor 44, when there is a proper adjustment of the various steps of the process. At the same time glycerine is continuously removed as a by-product, and the diluent may be recovered for subsequent use. The time required for saponiflcation depends on such factors as temperature, degree of divsion of the hydroxide material, and intimacy of mixing. Two saponification kettles have been shown and should be sufiicient to maintain a continuous spray in the spray chamber. However, it will be understood that more of these kettles may be connected to the system if found necessary.

The soap may be delivered in" a dry state or a sufficient temperature may be maintained at the conveyor 44 to keep it in a, plastic condition. Such a condition will aid in maintaining the vacuum in the chamber l6.

The vapor outlet pipe 21 should be ofsufticient The length of the tube 50 and the rate of rotation, as well as the temperature thereof, are adjusted so that the materials fed in the upper end at a predetermined continuous rate will be thoroughly mixed and saponii'led to the desired amount when they reach the opposite end of the tube, whereupon the fluid gel is fed into the pine l5 which delivers it to the chamber 1 6 through the nozzle 26.

In some instances it is not necessary to rotate the reaction tube 50, in which case the motor 5| and driving mechanism may be omitted.

If a longer reaction time is desired, a greater length of travel for the mixture during saponification may be provided by the arrangement shown in Fig. 3, in which the reaction tube 54 is shown coiled within the container 55, the latter being provided with inlet and outlet connections 56 to permit the heating medium to be circulated around the coiled tubing.

The properfunctioning of the apparatus of Figs. 2 and 3 will depend on the feeding of measured quantities of the materials into the reaction tubes 50 or 54. Any suitable measuring devices, well known in .the art, may be used for this purpose. Motor driven piston pumps 51 and 58 have been indicated for feeding the liquid saponiflable material and the liquid diluent respectively, while, a motor driven conveyor 59, feeding from a hopper, has been indicated for delivering a measured quantity of the solid hydroxide. These devices feed directly into the pipe 60 which is connected to the reaction tube of either Fig. 2 or Fig. 3. The speed of the motors may be adjusted to deliver each material at the proper rate.

The saponification process using a diluent with the saponifiable material and the hydroxide has been used before in a single batch process. The soap produced by,this known process has a portion of the diluent remaining in contact with it which has to be subsequently removed by washing with a solvent. The present invention eliminates this washing step, the soap being completely free from diluent, if desired. Also, in the prior known batch process, a large amount of the dilu, ent is necessarily provided, because, as partial pressure distillation takes place, the diluent is higher than the theoretical.

of the spray chamber I6.

oil will fall to the bottom as a grease.

removed from the mixture and the mixture becomes continuously more viscous. In order to insure the proper proportion of diluent towards the end of the batch process, it is necessary to provide a large amount at the beginning. The present continuous process of saponification uses less of the diluent, because there is always the same proportion of diluent, saponifiable material, and hydroxide at the point where the distillation takes place, as there is at the beginning. It is only necessary, therefore, to provide sufiicient diluent to accomplish the desired purpose at the moment when the liquid leaves the spray nozzle.

However, less of the diluent is required for another reason. While the theoretical ratio of the diluent to glycerine can be calculated for any given temperature, this theoretical ratio is very difilcult to attain, especially in industrial practice. The closeness with which this theoretical ratio is approached is dependent upon such factors as rate of distillation, intimacy of contact, and amount of surface exposed for distillation. 'While the diluent to glycerine ratio can be improved in the batch method (1. e. less diluent per unit of glycerinefby increased agitation, the actual ratio obtained is still much I have found that by spraying this soap gel into the spray chamber, a much better ratio of diluent to glycerine may be secured. This means less heat required to. distill over a unit quantity of glycerine. while the theoretical ratio of diluent to glycerine is more disadvantageous than under atmospheric pressure, I have found that the ratio of diluent to glycerine obtained by spraying into vacuum is better than obtained by a batch distillation under atmospheric pressure.

The proportions of diluent to the soap making materials may be adjusted so that all of the diluent is vaporized in the spray chamber and passes into the condenser and is removed. However, if desired the adjustment of quantities may be such as to leave a portion of the diluent in the precipitated soap which falls to the bottom Because of this, the process may be used for making special soap, such as. naphtha soap, which has a quantity of naphtha in the finished product. In this case naphtha may be used as the diluent, and a sumcient quantity may be used and other conditions may be adjusted so that the soap particles falling to the bottom will have some of the naphtha combined therewith, Stable naphtha soap may Thus,

be made in this manner without any necessity for the additional step of adding naphtha, which has been necessary heretofore, and with a great deal larger percentage of naphtha than has been considered practicable. With my process as much as 40% of naphtha may be incorporated in the soap.

Soap greases may be made with the process of the invention by adding lubricating oil to the ingredients introduced into the apparatus. After saponification has been completed in the saponification kettles H3 or H of Fig. 1, or the tubes of Fig. 2, or .54 of Fig. 3, the soap gel including the lubricating oil is sprayed into the spray chamber l6 whereupon the glycerine and volatile diluent are vaporized and the soap and heavier Greases with from to 90% of soap may be made in this manner.

As has been stated above, when the proper proportion of diluent and soap forming materials are provided, and the temperature and time of heating is sumcient, complete saponiflcation may be produced before the gel is introduced to the spray chamber. However, I may change the proportions of the reactants to produce partial saponification and then spray the gel into the spray chamber. By this means I may produce partial saponification products, such as glycerima mono-stearate, glycerine di-stearate, glycerine mono-oleate or glycerine di-oleate.

A feature of the invention is the particular gel structure of the soap which is produced by the process. This gel structure gives the soap a flufly or spongy characteristic andmakes it dissolve in water much quicker than soaps produced by other processes. The reactive effect of the soap is therefore speeded up. Because of this gel structure, the naphtha soap made by my process holds more naphtha and holds the naphtha more tenaciously, since each particle of soap absorbs naphtha rather than being merely coated with it. Lubricating grease made by this process is more stable, since the soap holds the lubricating oil more firmly and separation of the two is prevented.

It has been stated that anhydrous alkali is preferred for the saponifying reagent. The presence of water lessens the homogeneous heating eifect of the diluent, since water is not miscible with the fat. It also requires more heat to vaporize it and when vaporized with the glycerine, forms a dilute solution of glycerine, so that where glycerine is to be obtained as a by-product of the process, the water must be subsequently separated therefrom. Water-free glycerine may be directly obtained from the present process if an anhydrous reagent is used.

The diluent has been referred to as "substantially inert to the reactants and. the products of reaction. To obtain a pure product with the process operating at maximum efficiency, a completely inert diluent shouldbe used, but under certain conditions some reaction between the diluent and other ingredients may be tolerated.

It will be seen from the above description that I have provided a process for making soap which may be carried on continuously and which provides a soap of superior quality and at the same time permits recovery of the by-products. The process requires simple apparatus which is easily set up and maintained.

Since certain changes may be made in carrying out the above process and in the product, and modifications effected in the apparatus for practicing the principle thereof, without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 7

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The continuous process or saponirlcation which comprises the steps of mixing a saponifiable material, a saponifying alkali, and a volatile diluent, heating said mixture to eifect saponification, providing sufficient sensible heat to vaporize the diluent and the hydroxy component of the products of saponfication at a predetermined pressure, discharging the saponified mass in a finely divided condition in a zone of lower pressure, and flashing off the volatile constituents of the saponified mass, thus precipitating. the nonvolatile portions.

2. The continuous process of saponification which comprises mixing a saponifiable material, a

x aseopto I and the hydroxy component of the products of saponiflcatlon at a predetermined pressure, and continuously discharging the saponified mass in a finely divided condition in a zone of lower pressure. i

3. The continuous process -of saponification which comprises mixing asaponifiable material, a saponifying alkali, and a volatile diluent which is substantially inert to said material and said alkali and to the products of saponification and is immiscible with water and the hydroxy'components of the products of saponification, continuously passing the mixture through a heated reacting zone to effect saponification, providing suflicient sensible heat to vaporize the diluent and the hydroxy component of the products ut saponification at a predetermined pressure, continuously discharging the saponii'led mass in a finely divided condition in a zone of lower pressure, and flashing oil the volatile constituents of the saponified mass, thus precipitating the nonvolatile portions.

4. The process of manufacturing soap which comprises the steps of mixing soap making materials and a diluent which is immiscible with water' and substantially inert to the saidimaterials and the products of saponification and boils at a temperature less than 300 C. at a predetermined pressure, heating said mixture at a pressure higher than said prcdeterminedpressure so as to produce saponification, continuously spraying said mixture into an atmosphere of said predetermined pressure, whereby vaporization of the glycerine produced by saponification and of the diluent takes place and the soap produced by saponification is solidified, continuously removing the vapors so formed, and continuously collecting and removing the solid soap.

5. The process of manufacturing soap which comprises heating a mixture of soap making materials and kerosene to a temperature sufilcient to cause saponification and for a period of tlme'sufficient to produce the desired amount of saponification, spraying the mixture continuously in an atmosphere of reduced pressure and at a temperature sufllcient to cause vaporization of the kerosene and the hydroxy component of the products of saponification, removing the vapors produced by the spraying action, and collecting the 'solid material formed thereby.

JOSEPH JOHN JACQIBS.

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