CA2157660A1 - An improved process for the distillation-based separation of multicomponent mixtures by steaming - Google Patents

Abstract

The present invention relates to a process for intensifying and/or accelerating the distillation-based separation of multicomponent mixtures using a stream of steam to facilitate the removal of steam-volatile compo-nents of the starting material ("streaming"), charac-terized in that a starting material which is liquid under the treatment conditions is steamed in finely sprayed form. The process is preferably carried out with super-heated steam under the working pressure which, more particularly, is at least partly used as a propellent gas for spraying the liquid phases to be purified. The material to be processed is best sprayed in multicom-ponent spray nozzles using this propellent gas.
The process according to the invention may be used for a broad range of applications by adaptation of its parameters, more particularly the working temperature and pressure.

Description

H 0689 PCT / 03.01.1994 An improved process for the distillation-based separation of multicomponent mixtures by steaming Field of the invention This invention relates to proposals for intensifying and/or accelerating the distillation-based separation of multicomponent mixtures of at least partly organic origin using a stream of steam to facilitate the removal of steam-volatile components of the starting material. The teaching according to the invention is particularly concerned with the purification steps widely used on an industrial scale which come under the general heading of "steaming". However, the working principle according to the invention goes beyond this in its application. The invention is concerned quite generally with the separa-tion by distillation of starting materials, more par-ticularly starting materials which are liquid under working conditions, where steam can be used as a distil-lation aid.

Prior art The working principles of steam distillation forseparating organic mixtures and, in particular, for purifying corresponding valuable materials or mixtures thereof are long-established chemical knowledge, see for example L. Gattermann "Die Praxis des organischen Chemi-kers", 33rd Edition (1948), Walter De Gruyter & Co.
Verlag, pages 26 to 28 and 252. The principles described therein for laboratory practice are applied in various industrial fields in such diverse ways that it is only possible here to refer to a few characteristic applica-tions.
The purification of fats and oils of vegetable or animal origin involves a multistage treatment in which steaming of the prepurified material is usually carried out as one of the last steps. A key technical objective of this particular treatment step is to deodorize the prepurified material. Unwanted and, in particular, foul-smelling impurities often present only in traces are removed from the useful material or mixture of useful materials by steam distillation. However, steaming may also be used as a distillation aid, for example to facilitate the removal of short-chain fatty acids from the natural fats and oils. The literature on this sub-ject is represented, for example, by "Ullmanns Encyklopa-die der technischen Chemie", 4th Edition, Vol. 11 (1976), pages 479-486; Kirk-Othmer "Encyclopedia of Chemical Technology", 3rd Edition, Vol. 9 (1980), pages 816-820 and E. Bernardini "Vegetable Oils and Fats Processing" in "Oilseeds, Oils and Fats", Vol. II (1983), Interstampa-Rome, Chapter VII, pages 221-251 (Deodorization of Fats and Oils). The purification processes described in this literature, which are carried out on an industrial scale on the principle of steam distillation or rather steam-ing, operate in vacuo and at high temperatures. Forexample, steaming is carried out under pressures of Z to 30 mbar and at temperatures of 150 to 290C. The quan-tity of steam used and the treatment time are determined by the particular process selected. Batch processes, semicontinuous processes and continuous processes are known. In all these various processes, the steam is passed through the molten and superheated fat or oil in finely dispersed form. In semicontinuous and continuous processes, other aids may also be provided to increase the surface between the steam and the oil phase to be purified.
More recent publications include D. Osteroth "Taschenbuch fur Lebensmittelchemiker und -technologen", Vol. 2, Springer Verlag, Berlin, 1991, 101-103. This publication is concerned in particular with modern technologies for removing odor-emitting and taste-impart-ing substances by steaming in the refining of fats and oils using steam distillation or stripping in vacuo. In the case in point, the taste-imparting and odor-emitting substances are essentially aldehydes and ketones accom-panied by other volatile components, such as free fatty acids, sterols, tocopherols, etc. In terms of equipment, the steaming process may be carried out discontinuously, i.e. in batches, semicontinuously or continuously.
Continuous processes have been increasingly adopted for medium to relatively high outputs. Preferred treatment pressures are of the order to 2 to 5 mbar, the treatment temperature being in the range from 240 to 260C, depend-ing on the type of oil. By using newly developed fal-ling-film countercurrent installations, the consumption of steam can be minimized, for example to between 1 and 3% of the quantity of oil. To avoid wastewater problems, the vapor streams containing the organic constituents removed have to be worked up.
However, the purification or rather deodorization in question is not only important for raw materials. Prod-ucts obtained by chemical synthesis and by the chemical conversion of raw materials of natural origin also require such purification steps. The processing of fatty acids, the purification of fatty alcohols and the produc-tion of, in particular, liquid esters suitable for processing in the field of cosmetics, pharmaceuticals and foods are mentioned purely by way of example at this juncture. The following individual representatives are listed purely by way of example: Guerbet alcohol, oleic acid ester, soybean oil epoxide, isopropyl myristate, triacetin and the like.
Another typical field of industrial significance for the use of purification by steaming is the removal of residues based on ethylene oxide and/or propylene oxide from reaction products which have been produced by ethoxylation and/or propoxylation of organic compounds containing at least one active hydrogen atom. Compounds of this type are extremely important, for example, as nonionic surfactants or as intermediate products for the production of anionic surfactant compounds. They are used, for example, in the field of detergents and, on a wide scale, in the field of cosmetics and pharmaceutical auxiliaries. From their production, the reaction prod-ucts initially obtained contain traces of ethylene oxideand/or propylene oxide and of unwanted secondary reaction products, such as dioxane. The removal of these residues from the alkoxylated derivatives is a legal requirement and is an essential step of the production process. In this case, the steam distillation or rather steaming of the reaction products initially obtained for removal of the unwanted impurities is the process step carried out on an industrial scale, see for example EP-Al-0 283 862, DE-Al-34 47 867, US-PS-4,143,072 and the literature cited therein.
In a modification of the working principle mentioned above, however, it is also possible to heat the useful materials or mixtures of useful materials to be purified, preferably in vacuo, and then to subject them to partial concentration by evaporation and purification on the principle of steam distillation. It is known that additional, optionally superheated steam can be used for this purpose. If desired, the process products obtained, which are relatively low in water but freed from im-purities, may be subsequently converted into an aqueouspreparation, cf. for example DE-Al 30 44 488 and DE-A 33 43 802 which describe processes for the production of ether sulfates of reduced dioxane content.
It is also known that the purification of organic useful materials and mixtures of organic useful materi-als, more particularly their deodorization and/or theremoval of unwanted impurities, can be carried out using non-condensible gas phases as a distillation aid. The preferred distillation aid in this case is gaseous nitrogen which may be used to facilitate the removal of the more volatile components from mixtures, cf. for example J-AS-5414/81. According to this document, polyalkylene glycol derivatives - for example for use as emulsifiers, lubricating oils, starting materials for plastics, detergents, cosmetics and the like - are subjected to purification and deodorization by the injection of gaseous nitrogen or steam into the liquid to be purified at gO to lOO~C/30 torr. It has also recently been proposed in connection with the above-mentioned deodorization of edible oils and/or fats to use non-condensible inert gases, more particularly nitrogen, instead of steam as a stripping aid, see for example EP-A2-015 739.
US-PS-4,443,634 describes a process for the purifi-cation of fatty alcohol polyglycol ethers, in which the material to be purified is sprayed into a chamber from which the impurities can be removed in vapor form.
Corresponding mixtures containing less than 2~ by weight of the impurities to be removed, based on the liquid starting material, are described as the starting material to be purified. The material to be purified is said to be sprayed into an inert atmosphere, the pressure having to be selected so that droplets between 50 and 100 ~m in size are formed. These droplets are said to be exposed to the inert gas atmosphere for a matter of seconds and then collected. Nitrogen, helium and argon are mentioned as inert gases. The impurities to be removed by this spray treatment are, in particular, ethylene oxide, propylene oxide, dioxane, water and alcohol. The liquid phase may also be repeatedly sprayed into the inert gas atmosphere in successive process steps.
In their earlier German patent application DE-A 42 37 934, applicants describe a process for improving the purity and, in particular, the odor and color quality of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning products (starting material) which is characterized in that an impurity-laden starting material is treated with superheated steam, bleaching agents being used in the starting material to obtain improvements in color. In a preferred embodiment, the impurity-laden starting materi-al is subjected to the treatment with superheated steam in fine-particle form and, in particular, in admixture with water and, if desired, is at least partly dried.
This treatment with the superheated steam is best carried out in a spray zone and/or a fluidized bed. The dis-closure of this earlier German patent application DE-A 42 37 934 is hereby specifically included as part of the disclosure of the present invention.
The teaching of this earlier application is based on the surprising observation that, in particular, signi-ficant olfactory improvements in starting materials of the described type can be obtained by applying the principles of drying with superheated steam - as dis-closed in other earlier documents and in German patent applications in applicants' name - to an impure starting material. For example, very effective deodorization and, ultimately, a corresponding separation effect can also be obtained by drying with superheated steam.
Information on the principles of drying with super-heated steam can be found in the following patent docu-ments and earlier German patent applications in appli-cants' name: DE-A 40 30 688, DE-A 42 04 035, DE-A 42 04 090, DE-A 42 06 050, DE-A 42 06 521, DE-A 42 06 495, DE-A 42 08 773, DE-A 42 09 432 and DE-A 42 34 376. The _ 2157660 teaching according to the invention as defined in the following for intensifying and/or accelerating the separation of multicomponent mixtures by distillation is based on the findings and working rules according to DE-A 40 30 688 and the earlier German patent applications mentioned. Accordingly, the disclosure of this publica-tion and the earlier applications cited is also hereby specifically included as part of the disclosure of the present invention which is to be understood in conjunc-tion with the further findings and working rules de-scribed hereinafter.
Before the teaching according to the invention is discussed in detail, a totally different field of in-dustrial application is mentioned in the following to help in understanding the principles of steam distilla-tion. It is known that difficult distillation-based separations can be simplified by application of the principle of steam distillation. For example, the removal of unreacted fatty alcohols in the production of nonionic surfactant components from the class of alkyl polyglycosides (APG) is described in EP-B-0 092 876 and other corresponding applications. According to this document, the distillation of the APG-containing crude product is carried out in vacuo in a thin layer evapora-tor. The removal of the free fatty alcohol to be dis-tilled off can be promoted by exposing the starting material with its increased surface (the starting materi-al is spread out over the inner surface of the thin layer evaporator) to the stream of steam passing through the evaporator.

The teachinq accordin~ to the invention In a first embodiment, therefore, the present invention relates to a process for intensifying and/or accelerating the distillation-based separation of at ` 2157660 least partly organic multicomponent mixtures using a stream of steam to facilitate the removal of steam-volatile components of the starting material (also referred to hereinafter as "steaming"), characterized in that a starting material which is liquid under the treatment conditions is steamed in finely sprayed form.
In the process according to the invention, the steaming treatment is carried out with superheated steam under working pressure. In one particularly important embodi-ment, the liquid phase to be purified is sprayed with theassistance of a propellent gas, for which purpose it can be of particular advantage to use multicomponent spray nozzles. In this embodiment of the invention, super-heated steam is at least partly used as the propellent gas.
In a modification of the process, however, an at least substantially water-free starting material liquid under working conditions can be sprayed into a stream of the superheated steam without the aid of the propellent gas. This embodiment, which is characterized by the absence of propellent gas, simplifies decoupling of the particular quantity ratios required between superheated steam and the starting material to be purified without losing any of the advantages of easier mass transfer -attributable to the greatly increased surface - from the finely sprayed organic liquid phase to the surrounding continuous phase of the steam superheated at working pressure.
In further embodiments, the invention relates to the application of this process in various technological fields. One of the key f ields with which the invention is concerned is the purification and, in particular, the deodorization of fats and/or oils to enable them to be used, for example, as foods, in the cosmetics field and/or as pharmaceutical auxiliaries. Another field of application is the production of flavorings and flavoring concentrates.
Another important application lies in the use of the process for improving the purity of useful materials and mixtures of useful materials of vegetable and/or syn-thetic origin from the field of wetting agents, deter-gents and/or cleaning preparations, more particularly for their use in the treatment of textiles, for example in laundry detergents, cosmetics and/or pharmaceutical auxiliaries.
More particularly, the invention relates to the use of the described process for the purification of alkoxy-lated useful materials and mixtures of alkoxylated useful materials, more particularly for the removal of impuri-ties, such as unreacted residues of E0, P0 or secondaryproducts thereof, such as 1,4-dioxane.
In addition, however, the teaching according to the invention relates quite generally to the application of the working principles described in the following as a distillation aid in the separation of at least partly non-volatile mixtures.

Particulars of the teachinq according to the invention A crucial aspect of the teaching according to the invention lies in the following reversal: in the conven-tional deodorizing of fats and oils, for example, by the batch method, the liquid to be deodorized is initially introduced as the continuous phase while the steam used for steaming is introduced into and passed in finely dis-persed form through the continuous liquid phase to bepurified, for example through star-shaped or ring-shaped or otherwise configured injection systems with a plura-lity of outlet openings for the steam. The teaching according to the invention reverses this principle. The starting material which is liquid under treatment condi-`- 215766~
-tions is brought into phase contact with the steam in finely sprayed form, the steam generally forming the continuous phase.
The outcome of this reversal is a considerable increase in the liquid surface per unit volume of liquid phase to be treated which is crucial to the mass transfer from the liquid phase to the vapor phase. The specific liquid surface crucial to mass transfer can be increased, for example, by a factor of 10Z to 105 and, on average, by a factor of approximately 103.
This form of presentation of the liquid phase to be steamed with its substantially increased surface creates the possibility of extreme intensification and/or accel-eration of the steam-supported separation of the multi-component mixtures in accordance with the objective ofthe invention. Whereas treatment times of, for example, 6 to 10 hours are required for the conventional steaming of, for example, fats and oils by the one-stage process and whereas treatment times of several hours are still required even in the highly developed, conventional continuous processes, it is possible by adopting the procedure according to the invention to obtain lasting cleaning results after a matter of seconds. The ad-vantages which this affords are quite clear. Not only can a very much quicker working-up process be applied, it is also possible in accordance with the invention safely to control the temperatures to which the material to be purified is exposed within certain limits. The liquid to be deodorized can be sprayed by methods known per se.
The broad scope of the relevant technology on single-component and/or multicomponent nozzles and the associ-ated processes and process parameters are available for this purpose. There is no need to maintain long resi-dence times of the material to be deodorized in the sprayed state, particularly if the secondary principles according to the invention described hereinafter are also applied. If desired, the conversion of the gas to be purified into the finely sprayed state and the interac-tion of the continuous steam phase may be repeated S several times. The steam already used and/or fresh steam may be used in the individual spraying stages. The repeated spraying cycle may be carried out in a single unit or in a plurality of separate successive units.
Even where the repeated spraying process is applied, the material to be treated is rarely, if ever, exposed to high temperatures for more than a few minutes. Above all, the working conditions used in the separate stages, more particularly the adapted and optimized choice of the working pressure and temperature, can also be decoupled.
The technology according to the invention also provides for batch operation or continuous operation.
Examples of characteristic embodiments of the process according to the invention are illustrated in Figs. 1 to 3 of the accompanying drawings which will be discussed in more detail hereinafter.
It is clear that the key process principle described in the foregoing can be applied with adaptation and optimization of the particular process pressure to be used, depending on the character of the material to be treated. Accordingly, steaming in the spray zone may be carried out under normal pressure or under reduced pressures or even under excess pressures, depending above all on the volatility of the material to be treated and the impurities to be removed. Basically, the disclosures and specific numerical data of the cited prior art on steaming are applicable in this regard.
The choice of the particular working pressure determines the boiling temperature of the water under working conditions. According to the invention, steaming is carried out with steam superheated under the par-215766~

ticular working pressure. Accordingly, it is preferredto keep the steam phase at temperatures above 100C for working under normal pressure. Particular significance is attributed in this regard to the steam temperatures used. The particular temperature to be selected for the superheated steam is again influenced or rather deter-mined by a number of parameters. Key parameters in this regard include, for example, the steam volatility and the quantity of components to be converted into the vapor phase from the multicomponent mixture to be treated.
However, another factor to be taken into account is the temperature sensitivity of the material to be treated as a whole. As stated in detail in the following, its entry temperature into the spraying zone also has to be taken into account. The following principle does of course apply in this regard, as discussed for example in DE-A-40 30 688 cited at the beginning in connection with spray drying with superheated steam: if the material to be steamed is sprayed into the superheated steam at a temperature which is lower than the boiling temperature of water under working pressure, the superheated steam first condenses spontaneously on the cooler starting material, the heat of condensation being transferred to the finely sprayed material so that the individual droplets are heated to the boiling temperature of water under working conditions. It is only when this boiling temperature of the water is reached in the individual droplets that effective steaming takes place in accor-dance with the object of the present invention. Tempera-ture profiles in individual sprayed droplets of this typemay be entirely desirable and selectively established in special cases. In general, however, the material to be steamed is sprayed into the steam phase with a minimum temperature which corresponds at least substantially to the boiling temperature of the water under working pressure.
The temperatures of the superheated steam are preferably at least 10 to 30C and, more preferably, at least 50C above the boiling temperature of the water under the particular working pressure selected for the purification stage. Providing there are no basic objec-tions, for example arising out of the temperature sensi-tivity of the material to be steamed, the steam is used at distinctly higher temperatures. Thus, it may be advisable for the steam to have a temperature at least 100C and, more particularly, at least 150 to 200C above the boiling temperature of the water under the working pressure of the purification stage.
Using the parameters to be taken into consideration in this regard by the expert, such as temperature sensi-tivity of the multicomponent mixture to be treated, the mass ratio of steam phase to liquid multicomponent mixture to be steamed and the like, considerable absolute steam temperatures may be used. These working tempera-tures of the steam - now isolated from the particular boiling temperature of the water under working conditions - may be for example up to about 500C and are preferably in the range from about 100 to 400C. It is only in the treatment of highly temperature-sensitive starting materials containing, for example, mixture components susceptible to damage at temperatures well below 100C
that the steam is used at temperatures below 100C. In this case, the steam treatment must of course be carried out in a sufficient vacuum.
The prior art relating to such purification steps by steaming provides adequate references to optimized combinations of working pressure and the temperature of the steam phase. According to the relevant literature cited above, the known deodorization of natural fats and oils by steaming takes place under greatly reduced pres--2l~766a sures, for example in the range from l to 20 mbar, and at the same time using high material temperatures well above 100C, for example in the range from 150 to 270C. The procedure according to the invention does of course also encompass such extreme combinations of temperature and pressure; the temperature of the superheated steam used may substantially correspond to the temperature of the liquid to be steamed and, if desired, may even be below that temperature although, in general, an entry tempera-ture above the temperature of the liquid will generallybe selected. It is clear from general specialist know-ledge that this particular embodiment of the invention, which does of course create the possibility of introduc-ing additional evaporation energy through the superheated steam used, provides for optimal results in regard to the acceleration and/or intensification of the material to be removed via the steam phase.
In the process according to the invention, there-fore, the free-flowing material to be purified which, in particular, is present as a liquid phase at the working temperature is sprayed into a stream of the preferably superheated steam and the liquid phase is subsequently separated from the steam phase. Particulars of useful designs of the stages involved can be found in the following in the discussion of Figs. 1 to 3 of the accom-panying drawings. The special aspects mentioned above in connection with particularly preferred embodiments of the teaching according to the invention are discussed before-hand.
In the embodiment of the invention in question, the liquid phase to be purified is sprayed with the assis-tance of a propellent gas. Various constructions of corresponding spray units, more particularly spray nozzles, are known from the relevant prior art, see for example H. Brauer "Grundlagen der Einphasen- und Mehr-~ 21S7660 _ phasenstromungen" in GRUNDLAGEN DER CHEMISCHEN TECHNIK, Verfahrenstechnik der chemischen und verwandter Industri-en, Verlag Sauerlander, Aarau und Frankfurt am Main (1971), pages 308-323; A.H. Lefebvre "Atomization and Sprays" Hemisphere Publishing Corp. New York (1989), pages 10-20; Chemical Engineering, Vol. 2, Unit Opera-tions (2nd Edition 1968), Pergamon Press, Oxford/New York, pages 602-617; and R.H. Perry et al. in "Chemical Engineering Handbook" (5th Edition 1975), MacGraw-Hill Book Co., New York "Phase Dispersion/Liquid-in-Gas Dis-persions", pages 18-61 to 18-65.
Particularly preferred embodiments of the invention use multicomponent spray nozzles and propellent gas. In the most important embodiment of the invention, super-heated steam is at least partly used as the propellentgas. In the crux of the teaching according to the invention in question here, the most important embodiment is the use of superheated steam as sole propellent gas for spraying the liquid multicomponent mixture and converting it into the finely dispersed liquid phase. It has surprisingly been found that, where superheated steam is used as the propellent gas, the transfer of components to be separated from the liquid phase to the superheated steam phase is intensified - presumably through the intensive mixing accompanying the spraying process - to such an extent that the purification result achieved in the particular process cycle can be established in fractions of a second. The mode of operation and ad-vantages of the process according to the invention are easy to comprehend. Taking into account the particular process of formation of the sprayed droplets as described in the cited literature, which generally includes lamel-lar spreading of the liquid phase to form an extremely thin layer, the intensity of the measure according to the invention is understandable so far as the cleaning result is concerned. In addition, the general specialist knowledge of the process engineer on the enhancement of this effect through the choice of suitable multicomponent nozzles may be applied within the scope of the teaching according to the invention.
In one embodiment, the teaching according to the invention enables virtually all the steam used to be employed as a propellent in the spraying of the liquid phase to be purified. In important embodiments, however, a predetermined direction of flow of the gas phase can be additionally established and maintained in the spray compartment by a partial stream of, in particular, superheated steam. For example, vertically arranged reaction compartments can be operated in countercurrent in such a way that the liquid is sprayed downwards with superheated steam as the propellent gas while, at the same time, a partial stream of the superheated steam flows upwards in countercurrent to the sprayed material.
According to the invention, the special features of the process according to the invention and its close re-lationship to drying with superheated steam in accordance with the disclosure of DE-A-40 30 688 and applicants' other earlier applications cited above make it possible both to subject a substantially water-free starting material to purification by steaming and to subject a water-containing starting material to treatment with the superheated steam in the spray zone so that purification by steaming is combined with at least partial drying.
As mentioned at the beginning, an important modifi-cation of the process according to the invention ischaracterized in that the liquid, at least predominantly organic starting material to be purified is finely sprayed into a stream of the superheated steam without the use of a propellent gas based on superheated steam.
The uncoupling of the superheated steam as a working 21~7660 medium in the spraying process - single-component nozzles may be used in known manner in this embodiment - provides in particular for a reduction in the amount of super-heated steam used per basic unit of the organic liquid to be purified. By regulating the droplet size of the liquid to be sprayed in known manner and establishing extreme fineness in the sprayed liquid, mass transfer from the sprayed liquid phase into the surrounding continuous phase of the superheated steam can be accel-erated even in this embodiment to such an extent thatuseful cleaning results are obtained in a matter of seconds or, in extreme cases, in a matter of minutes.
More particularly, use can be made in this particular embodiment of the possibility described at the beginning of operating in several stages, if desired with simul-taneous decoupling of the working parameters in succes-sive stages. If such a multistage procedure is adopted, the two working principles of spraying with superheated steam as the propellent gas and spraying the organic liquid phase into the continuous superheated steam phase without using a propellent gas may even be combined with one another if desired.
The operating parameters of the particular working stages selected and used in accordance with the invention correspond to the relevant parameters of the prior art.
Thus, the working pressures may be selected in the range from about 1 to 50 mbar and more particularly in the range from about 3 to 30 mbar if low-volatility starting materials, for example fats and/or oils or natural origin, are to be purified. The same also applies to processing products and/or synthetic starting materials of comparably low volatility. However, in important embodiments of the teaching according to the invention, purification in the spray zone is carried out under normal pressure or only moderately reduced pressures.

21~766~

Increasing the intensity of mass transfer through the use of superheated steam as propellent gas in the particular-ly preferred embodiment of the process according to the invention often enables separation to be effectively carried out even when the working pressures are not reduced to the relatively low values hitherto regarded as necessary. Herein lie important possibilities for simplification and for saving plant and operating costs in purification by steaming.
The particular quantities of superheated steam required are determined by the parameters to be taken into consideration, more particularly by the choice of the starting material and the extent to which it is exposed to heat and by the particular process selected.
Normally, the quantities of steam used are between about 1 and 30% by weight and preferably between about 5 and 20% by weight of the material to be purified for the embodiment using superheated steam as propellent gas. In the embodiment where a single-component nozzle is used without the propellent gas effect of the superheated steam, quantities of steam in the range from about 2 to 10% by weight, based on the starting material to be steamed, can be particularly advantageous. Particularly suitable starting materials for the embodiment where no propellent gas is used are at least substantially free from water. Organic useful materials with a water content of less than 10% by weight, better still less than 5% by weight and more particularly less than 1 to 3%
by weight are preferred.
The average droplet size of the sprayed material is in the technically accessible range of, for example, 20 to 500 ~m and, more particularly, 50 to 200 ~m. The treatment time in the particular working stage is of the order of seconds and, as mentioned above, can be in-creased by multistage operation, although in that case it is still extremely short by comparison with conventional steaming processes, even in highly developed versions thereof.
The teaching according to the invention is described with reference to Figs. 1 to 3 of the accompanying draw-ings which relate to the treatment of a substantially water-free starting material.
Figures 1 and 2 diagrammatically illustrate the batch deodorizing of a material which is liquid and sprayable at the working temperature. By suitably selecting the particular apparatus, the batch deodorizing process may be carried out both at normal pressure and under reduced pressure.
Figure 1 illustrates batch deodorization in the tank 1 of which the wall is heat-insulated and/or provided with a heating system 2. Provided in the head part of the tank is a demister 3, for example in the form of a corresponding steam-permeable packing, below which one or more spray nozzles 4 are arranged. In the case illustrated, the spray nozzles are multicomponent nozzles operated with superheated steam as the propellent gas.
Part of the steam is delivered to the multicomponent nozzle 4 through the line 5 and the superheater 6. If desired, part of the steam may also be delivered to a distributor element 7 provided in the bottom part of the tank 1. By means of the pump 9, the liquid 8 to be purified is pumped off from the bottom of the tank 1 through the line 10, optionally passed through the heat exchanger 11 and introduced into the spray nozzle 4. The superheated steam laden with the impurities which have passed into the vapor phase is pumped off by the pump 13 through the line 12. The superheated steam may be subjected to controlled cooling in the heat exchangers 14 and 15, so that condensed parts of the material pumped off can be removed through 16, 17 and 18. After adequate -purification of the material 8 by steaming in accordance with the invention, the batch can be removed and a new batch of material to be purified can be introduced into the apparatus through the pipe 19.
The batch deodorizing process in a column diagram-matically illustrated in Fig. 2 corresponds in its key elements to the illustration in Fig. 1. However, a packing element 20 of the type known and used, for example, in modern separation columns for distillation and absorption is additionally provided between the spray nozzle 4 and the liquid phase 8 in the bottom part of the tank 1 as an additional phase separation aid. Corre-sponding packing elements of metal and/or plastic are standard working elements, more particularly for separa-tion by distillation, absorption and desorption in separation columns, cf. for example the pamphlet entitled "Trennkolonnen fur Destillation und Absorption (Separ-ation Columns for Distillation and Absorption)" of Gebru-der Sulzer AG, Produktbereich Chemtech Trennkolonnen, Winterthur, Switzerland (22.13.16.20-V.91-100).
The possibility of separating materials via one or more packs 20 as illustrated in Fig. 2 facilitates separation between liquid and gas phases even in columns where mixtures with a tendency to foam are processed.
Both here and in the installation shown in Fig. 1, the quantity of liquid 8 in the bottom of the tank 1 can be selected virtually as required.
Multistage steaming in accordance with the invention is illustrated in Fig. 3 which is based on continuous operation.
An optionally heatable column 21 is divided into three sections by sufficiently steam-permeable separating elements 22 and 23. The steam-permeable separating elements 22 and 23 may be formed in known manner, for example by suitable sieve plates or even bubble plates or the like. The function of the separating elements 22 and 23 on the one hand is to prevent the liquid product accumulating on their upper surface and introduced through the pipe 24 by means of the pump 25 (upper column section) or the liquid phase introduced into the first spray nozzle 28 through the pipe 27 by the pump 26 from passing through into the lower reaction compartment in such a way that the liquid phase can be removed at the bottom of the particular section of the separating column and further transported as required.
The crude product delivered through the line 24 by means of the pump 25 is heated in the heat exchanger 29 and introduced into the head of the column 21. The working steam laden with the impurities to be removed which issues from the head of the column 21 through the line 30 is first subjected once more to intensive ex-change with the freshly introduced liquid in the upper head part of the column. The bubble plates 31 are provided for this purpose in Fig. 3. This separating element may be used in particular to ensure reliable separation between gas phase and liquid phase in the ascending impurity-containing steam. Above the sieve plate 22, the liquid is pumped off through the line 32 by means of the pump 26 and directly delivered to the spray nozzle 28 where the liquid phase is finely sprayed by means of the superheated fresh steam introduced through the lines 33 and 34 as propellent gas. The sprayed liquid impinges on the separating element 35 which is again shown as a bubble plate in Fig. 3 and which effects a first separation between gas and liquid phase. The gas phase ascends through the sieve plate 22 and, by means of the pump 36, is pumped off from the separation column through the line 30 and the heat exchanger 37.
The liquid phase leaves the separating element 35 at its lower end and is collected by the sieve plate 23. By means of the pump 39, the continuous liquid phase col-lected is then pumped through the line 38 to the next spray zone containing the spray nozzle 40. In this spray zone, the liquid phase is again treated in accordance with the invention using the fresh steam introduced through the lines 33 and 41. The liquid sprayed in this treatment stage impinges on the packing 42. The observa-tions made in the foregoing in reference to Fig. 2 and the corresponding packing 20 are applicable to this treatment stage also.
The liquid which has now been purified in two stages passes downwards through the packing 42 and collects in the bottom of the separating column where it may again be treated with superheated fresh steam delivered to the distributor element 44 through the lines 33 and 43.
By means of the pump 46, purified liquid is dis-charged through 45 at the bottom of the column, cooled with crude product introduced in the heat exchanger 29 and removed through ~7.
Both for Figs. 1 and 2 and for Fig. 3, working pressures may be selected as required and adjusted in a predetermined manner in the interior of the separation columns. The pumps 13 and 36 are particularly suitable for pressure regulation around normal pressure or vacuum.
If it is desired to work under excess pressures for reasons of high volatility of individual product com-ponents, the pumps (g in Figs. 1 and 2 and 25, 26, 39 and 46 in Fig. 3) are particularly suitable working elements for moving the streams of liquid product.
As mentioned at the beginning, the teaching accord-ing to the invention applies both to the treatment of substantially water-free materials and to the treatment of water-containing materials. A common requirement for carrying out the process according to the invention is that it should be technically possible finely to spray 21S766() the multicomponent mixture to be treated under the working conditions, more particularly using superheated steam as the propellent gas. Those embodiments of the teaching according to the invention which relate to the use of corresponding water-containing materials and to their treatment by the process according to the invention are described in detail in the following.
It will immediately be appreciated that the teaching according to the invention can be divided into a number of special embodiments. This is attributable one the hand to the characteristics of the starting material, more particularly in regard to its water content and the physical characteristics of the water-free useful materi-al or mixtures of water-free useful materials under the working conditions and under normal conditions. On the other hand, the versatility of possible special embodi-ments derives from the objective of the teaching accord-ing to the invention: the teaching according to the invention not only seeks to achieve separation in the sense of conventional deodorization, drying of the useful material or mixture of useful materials may also be included in the scope of the process according to the invention. The particular apparatus to be used and measures to be taken in individual cases are therefore very largely determined by the particular material inter-relationships and the objective to be accomplished. The broad range of application of the technical procedure according to the invention is accessible by taking into account the teaching according to the invention and applying general specialist knowledge to the background of the teaching according to the invention. Individual characteristic examples are described in the following without any claim to completeness.
In a first special embodiment, a starting material containing water under working conditions, which is to be dried under process conditions and preferably freed from light steam-volatile impurities, may be subjected to the treatment according to the invention. Basically, how-ever, even the removal of water from a water-containing useful material or mixture of water-containing useful materials may be interpreted as distillation-based separation in the context of the teaching according to the invention so that, in this case, even the accelera-tion of drying by using superheated steam as propellent gas for finely spraying the starting material (preferably through suitable multicomponent nozzles) may represent an embodiment of the teaching according to the invention.
However, the particular aspects of the teaching according to the invention make pure drying such as this a special case which is hardly ever encountered in practice.
Useful materials and mixtures of useful materials of the type encountered in industrial-scale operation often contain at least traces of impurities which are dis-charged via the steam phase during the steaming and simultaneous drying steps of the process according to the invention. This applies in particular to the above-mentioned purification of useful materials and mixtures of useful materials from the field of wetting agents, detergents and/or cleaning preparations and associated useful materials which is discussed in applicants' earlier German patent application DE-A 42 37 934 already included as part of the disclosure of the present inven-tion. In the Examples of this earlier application, the slurry to be processed is sprayed through a two-component nozzle using nitrogen as the propellent gas and is dried in countercurrent with superheated steam. According to the invention teaching of the present invention, however, the superheated steam is directly used às the propellent gas. In this way, both the result of purification and also the drying of the mixtures used can be substantially improved and accelerated.
More particularly, the teaching of the earlier patent application cited above also concerns the produc-tion of purified materials and mixtures of purified materials which are solid after drying. Now, the teach-ing of the present invention extends to water-containing and spayable preparations of such useful materials or mixtures of useful materials. The results obtainable in the processing of such materials and the parameters to be observed to that end are the subject of applicants' earlier German patent application DE-A 42 34 376 cited at the beginning. The disclosure of this earlier applica-tion is hereby included once more as part of the disclo-sure of the present invention. This earlier application describes how a microporous structure can be developed and fixed in a material dried with superheated steam and - building on this - how mixtures of useful materials from the product range in question can be formulated in a hitherto unknown manner.
20In the embodiment just mentioned, the teaching according to the invention encompasses the combination of purification of the useful material or mixture of useful materials used by steaming and drying of the water-containing preparations used, the elements from appli-25cants' earlier German patent application DE-A 42 34 376 being taken into account at the same time.
Accordingly, the teaching according to the invention is concerned inter alia with a process which is charac-terized in that it uses solid useful materials or mix-tures of useful materials in the form of a free-flowing, sprayable water-containing preparation which are suitable under the steaming and superheated drying conditions for forming solids with an open-pore internal structure of which the plasticity and surface tackiness are limited to such an extent that the particles and/or the open pores -of their internal structure are largely prevented from adhering to one another, even under the conditions of exposure to the superheated steam. It can be particular-ly important in this connection to process the useful materials or mixtures of useful materials using water-soluble and/or fine-particle water-insoluble inorganic and/or organic auxiliaries which are preferably solid and non-tacky in their dry state.
In a second embodiment, however, the teaching according to the invention also encompasses the process-ing of useful materials or mixtures of useful materials in the form of water-containing preparations which flow freely under normal conditions. In this case, too, the separation of unwanted steam-volatile components may be advantageously combined with complete or partial drying with superheated steam. One example of materials of this type are water-containing alkoxylation products - liquid under normal conditions - of compounds containing at least one reactive hydroxyl group, for example corre-sponding water-containing preparations of nonionic surfactant components. Most applications of such alkoxy-lates presuppose the substantially complete removal of residues present in the process product, for example of ethylene oxide (EO) and/or propylene oxide (PO) and of the unwanted cyclic ethers, for example dioxane, formed as secondary alkoxylation products. The invention provides in a single process for the effective separation of these unwanted trace impurities and for the simul-taneous drying of the originally water-containing materi-al to a predetermined extent.
Taking general specialist knowledge into considera-tion, it will immediately be appreciated that the process measures and working tools to be selected in each indivi-dual case have to be adapted to the conditions determined in advance by the product properties. All embodiments of the invention presuppose fine sprayability, more partic-ularly using superheated steam as the propellent gas, for forming the steam-filled spraying zone required in accordance with the invention. Useful materials or mix-tures of useful materials which have retained theirfluidity under working conditions after the first spray-ing stage can be resprayed and hence delivered to a multistage process. Useful materials and mixtures of useful materials which are converted into solid compo-nents, more particularly by simultaneous drying, cannotreadily be delivered to a second process stage in the sense of the procedure according to the invention. If, in their case, a second working stage is to be carried out, the dried material should first be converted back into a sprayable liquid preparation.
In one preferred embodiment, the teaching according to the invention encompasses procedures in which, after separation from the purified material, the superheated steam phase laden with discharged components of the starting material is at least partly freed from those components of the starting material. In this way, useful materials can be separated from the laden steam phase and recovered and/or wastewater disposal problems can be prevented. If desired, however, the purified aqueous phase can also be circulated.
Basically, the impurity-laden steam phase can be worked up in any way known to the expert. General specialist knowledge may be used for this purpose. It has proved to be particularly effective to use membrane technology for this secondary working step of the proce-dure according to the invention. General specialist knowledge on this subject is represented, for example, by the books of JU.I. Dytnerskij "Membranprozesse zur Tren-nung flussiger Gemische (Membrane Processes for Separa-ting Liquid Mixtures)" VEB Deutscher Verlag fur Grund-~ 2157660 stoffindustrie, Leipzig, 1977, and M. Cheryan "ULTRAFIL-TRATION HANDBOOK", Technomic Publishing Co., Inc., Lancaster, Basel, 1986.
The choice and adaptation of the particular membrane separation process according to the type and characteris-tics of the membranes selected and the particular tech-nology to be used are determined by the particular mix-ture to be separated. The impurity-laden aqueous phase may be worked up in a single stage or even in several stages. The choice of suitable membranes extends from microfiltration via ultrafiltration and nanofiltration to reverse osmosis. Here, too, the particular technical procedure is determined by the relevant parameters of the mixture to be separated.
Figures 4 and 5 diagrammatically illustrate corre-sponding separation possibilities with reference to aqueous condensate phases which accumulate as a liquid phase through absorption of the fractions to be separated from the starting material and after condensation of the vapor phase, generally under normal conditions.
In Fig. 4, the steam treatment according to the invention is combined with working up of the impurity-laden waste steam or wastewater. The steam treatment step is carried out in a two-stage cascade arrangement, the following procedure being adopted:
The material to be steamed is delivered via the heat exchanger 48 and the line 49 to the head of the tank 50 where it is finely sprayed through one or more spray nozzles 51. Fresh steam is delivered through the line 53 to the distributor element 54 in the lower part of the tank 50 after heating to the required working temperature in the heat exchanger 52 and builds up the continuous phase of the superheated steam. Another possibility is to deliver this superheated steam at least partly as a propellent gas to the spray nozzle(s) 51 through the line 55.
At the bottom of the tank 50, the steam-treated liquid is pumped off through the line 57 by the pump 56 and introduced through the line 58 into the head of the second spray tank 59 where it is finely sprayed by means of the spray nozzle(s) 60. Superheated fresh steam is delivered to this spraying zone through the line 61 and the distributor element 62 in the lower part of the tank 59. Alternatively, the superheated steam may again be completely or partly delivered as propellent gas to the spray system 60 through the line 63. From the bottom of this second spray zone 59, the steam-treated liquid is pumped off through the line 65 by the pump 64 and can be removed through 66.
The superheated steam phase laden with the steam-volatile constituents taken up is removed from the head of the first tank 50 through the line 67 and from the head of the second tank 59 through the line 68 and delivered to the condenser 69 where it is condensed. The liquid accumulating is delivered through the line 84 to the intermediate tank 70. The aqueous phase collecting in the intermediate tank 70, which is laden with dis-charged organic constituents, is pumped off from the bottom of the intermediate tank 70 through 71 by the pumps 72 and 73 and introduced through the line 74 into the membrane separation unit 7S. The permeate passes through the semipermeable membrane 76 and can be removed through the line 77 and delivered, for example, to a conventional wastewater treatment station. The retentate which does not pass through the membrane is removed through the line 78. It may be partly circulated by the pump 73 via the line 74. The component to be taken from the circuit is removed through 79. The further utiliza-tion of these components discharged from the starting material by the deodorizing treatment according to the invention is determined by their potential value. If they are useful materials, they may be subjected to further processing or may be re-utilized. However, they may also be destroyed, for example by incineration.
Finally, Fig. 4 shows how non-condensed gas phase accumulating in the condenser 69 can be worked up. Under the effect of the blower 80, the non-condensed gas phase is delivered through the line 81 to the tower 82 filled with a solid absorbent and is fixed to the absorbent.
The step-by-step desorption of the absorbed components is carried out in known manner through the provision of a second absorption tower. The absorbed components may be delivered to the holding tank 70, for example through the line 83, and then worked up as described above together with the condensate delivered from the condenser 69 through the line 84.
Figure 5 illustrates a variation of the membrane separation process for the liquefied condensate from the preceding purification stage (not shown) using super-heated steam. The condensate of the superheated steamphase laden with discharged components of the starting material is delivered to the holding tank 70 through the line 84 and introduced through the line 71 into the first membrane separation stage 75 by the pumps 72 and 73 via the line 74. The permeate passes through the semiperme-able membrane 76 and is removed through the line 77. The retentate leaves this first membrane separation stage through the line 78 and can be partly circulated through the line 74 by the pump 73 and/or removed through the line 79 and either further processed and/or destroyed.
The permeate of the first membrane separation stage which is removed through the line 77 is delivered to the holding tank 85 and delivered through the line 86 to the second membrane separation stage 90 by the pumps 87 and 88 via the line 89. The permeate passes through the -semipermeable membrane 91 and is removed through the line 92, for example as sufficiently purified wastewater. The retentate leaves this second membrane stage through the line 93 and can be at least partly circulated through the line 89 by the pump 88. Instead or at the same time, the retentate may be circulated through the line 94 and returned to the holding tank 70 of the first membrane separation stage, as illustrated.
In the two-stage condensate purification process illustrated, it can be particularly useful to provide semipermeable membranes increasing in steps in their separation efficiency in the successive separation stages. For example, a microfiltration in the first stage may be combined with ultrafiltration or nanofiltra-tion in the following stage. However, the second separa-tion stage may also be based on reverse osmosis. Com-binations of ultrafiltration and nanofiltration or ultra-filtration and reverse osmosis are of course also pos-sible. Finally, it is also possible to combine more than two separation stages with one another.
The working principle of the invention has a broad scope of application. Without any claim to completeness, the following applications are mentioned by way of example: steaming, more particularly for deodorizing fats and/or oils for use, for example, in the field of foods, cosmetics and/or as pharmaceutical auxiliaries; improving the purity of useful materials and mixtures of useful materials of vegetable and/or synthetic origin, more particularly from the field of wetting agents, detergents and/or cleaning products, for example for their use in the field of textile treatment, cosmetics and/or pharma-ceutical auxiliaries; purification of alkoxylated useful materials and mixtures of such useful materials, more particularly for the removal of impurities of the type mentioned above.

H 0689 PCT 32 2 1 ~ 76 6 0 Broadly speaking, however, the teaching according to the invention is also suitable above all as a distilla-tion aid in the separation of at least partly low-vola-tility mixtures. By adapting the particular working conditions, more particularly temperature and pressure, the principle of simplified separation by steam distilla-tion can be effectively applied. The above-mentioned separation of excess free fatty alcohols from the reac-tion mixtures encountered in APG production is a typical example of this potential application of the invention.
However, an application of importance in exceptional cases may also quite simply be the effective removal of otherwise difficult-to-remove residues of water from the starting material and hence the effective drying of such useful materials or mixtures of useful materials. Here, too, the process according to the invention - by adapta-tion of its parameters, more particularly temperature and pressure - gives results which are often difficult and expensive to obtain in conventional separation processes.
The process according to the invention for the steam-aided distillation-based separation of mixtures may advantageously be applied in a very broad range of possible embodiments. The removal of small and very small quantities of troublesome impurities, which often involves considerable technical difficulties, can be achieved as effectively and technologically as simply as the separation of mixtures by steam distillation where considerable quantities or even predominant quantities of the starting material have to be separated from the distillation residue. One example of this is the recov-ery of flavorings which are discharged in the superheated steam phase and then separated and recovered therefrom.

2157~BD

E x a m p l e s Example 1 The esterification of fatty acid with glycerol to form a glycerol trioleate (Myritol 318~, a product of Henkel KGaA) was carried out in a reaction vessel at 180 to 220C using a catalyst. The water of reaction accumu-lating was removed first under normal pressure and then in vacuo. The esterification reaction lasted about 15 hours. The ester was then deacidified with 10% sodium hydroxide solution in a refining vessel, washed and dried in vacuo. After bleaching with diatomaceous earth as the bleaching agent and filtration, the residual fatty acid content is removed in a deodorizing stage.
To this end, the glycerol trioleate ester is sprayed through a two-component nozzle into a vertically arranged deodorizing vessel using superheated steam as the propel-lent gas. The ester collects at the bottom of the vessel and is pumped back to the spray nozzle. At the same time, superheated steam is introduced into the deodoriz-ing vessel through an injector system in countercurrent to the liquid. The steam is discharged together with the odor-emitting substances entrained therein through a vacuum system consisting of a steam jet compressor and a water ring pump. The dimensions of the vessel and of the nozzle and the operating parameters are shown in Table 1 below.

- 21576~0 Table 1 Dimensions 1. Deodorizing vessel Width (mm) 300 Height (mm) 1200 2. Two-component hollow cone nozzle Diameter (mm) Operating parameters - Liquid:
throughflow (kg/h) 10.
temperature (C) 160 - Steam (injection nozzle):
throughflow (kg/h) 4 pressure (bar) 4 temperature (C) 170 - Vacuum:
internal vessel pressure (mbar) 4 cooling water temperature (C) 10 After two-stage deodorization, the content of free fatty acid was reduced from 1.02% by weight to 0.08% by weight. After three-stage deodorization, the free fatty acid content falls to less than 0.01% by weight. The odor of the glycerol trioleate is evaluated in Table 2 below in the form of figures relating to the residual content of free fatty acids in % by weight.

21~7669 Table 2 Deodorization C8 fatty C10 fatty C12 Y Sthe free acid acid acidfatty % by % by % byacids weight weight weight Non-deodorized 0.66 0.36 <0.011.02 (starting value) 2 Stages 0.02 0.06 <0.010.08 3 Stages <0.01 <0.01 - <0.01 Example 2 The procedure is as described in Example l. A
cetostearyl alcohol (Lanette Ox, Henkel KGaA) is deodor-ized by spraying through a two-component nozzle.
The cetostearyl alcohol is a mixture of higher saturated fatty alcohols, predominantly cetyl alcohol and stearyl alcohol. It is a skin-friendly base material and consistency factor with emulsion-stabilizing properties for emulsions, more particularly creams and acidified hair tonics and also pharmaceutical ointments. The short-chain free fatty alcohols (C10 to C14) present from the production process reduce the quality of the product by their unpleasant odor. 95% by weight of these fatty alcohols are removed in a two-stage deodorizing process.
The following process conditions are established:
Cetostearyl alcohol:
throughflow 10 kg/h temperature 150C

35 Steam:
throughflow 4 kg/h pressure 4 bar temperature 150C

A pressure of 20 mbar was established in the deodor-izing vessel. The characteristic data of the subsequent-ly flaked, odorless cetostearyl alcohol are as follows:

Chain length: C10-lZ 0%
Cl4 0.5%
Cl6 49%
C18 50%
C20 . 5%
Rise melting point: 54C
Solidification point: 50C
Acid value: 0.02 Saponification value: 0.1 Iodine value: 0.1 Hydroxy value: 218 Density at 60C: 0.82 g/cm3 Example 3 The procedure is as described in Examples 1 and 2.
In this case, the residual fatty alcohol (chain length C1z_l8) remaining after the synthesis of an alkyl poly-glycoside (APG) is removed.
The APG was prepared by direct synthesis (single-stage process) in which the glucose insoluble in the fatty alcohol is directly reacted with fatty alcohol to form the alkyl polyglycoside. The reaction mixture consisted of 30% by weight of APG and 70% by weight of fatty alcohol. Most of the excess fatty alcohol was removed in a falling film evaporator at 10 mbar/160C.
The residual fatty alcohol content was 8% by weight.
This residual fatty alcohol content is reduced to < 1% by weight, as required by the specification, in a three-stage deodorizing unit. To this end, the APG starting material to be purified is sprayed through a two-com-._ ponent nozzle (diameter 1 mm) using superheated steam (160C) as the propellent gas. The operating parameters were as follows:

5 - Alkyl polyglycoside:
throughflow 10 kg/h temperature 180C

- Steam:
throughflow 3 kg/h pressure 4 bar temperature 160C

The viscous APG paste accumulating is removed from the deodorizing vessel by positive discharge. It is diluted with water to an active substance content of 60%
by weight and bleached. By virtue of the short residence time in the second stage of the fatty alcohol removal at the high temperature of around 160C, only slight brown-ing occurred. Accordingly, less effort is involved inthe bleaching of the aqueous APG paste with H2O2. In its aqueous form containing 50% by weight of active sub-stance, the APG product flows freely at around 40C.

Example 4 The procedure is as described in Examples 1 to 3.
A soybean oil was deodorized. The deodorization removes unwanted odor-emitting and taste-imparting substances which have largely been formed by oxidative and hydroly-tic chemical or enzymatic reactions. The substances inquestion are mainly aliphatic, saturated and unsaturated aldehydes of the C6l0 series, aliphatic ketones (methyl-heptyl, methylnonyl, methylundecyl ketone, etc.) and also low molecular weight fatty acids. In addition, the bleaching step provides the oil with an earthy odor. The 21~7660 hydrogenation results in a typical hydrogenation odor and taste. Hydrogenated soybean oil contains up to 37 vola-tile compounds, mainly higher aldehydes, ketones, lac-tones and alcohols. The soybean oil (T = 240C) was sprayed through the two-component nozzle with superheated steam as the propellent gas. Steam superheated to 170C
(p = 1 bar) was introduced through the injector. The vessel pressure was 5 mbar. After 4 circuits, the final free fatty acid content was 0.04% by weight. The sensory test was positive.

Example 5 The procedure was as described in Example 4. An olive oil was deodorized. The temperature of the oil was 220C. The requisite quality in regard to odor and taste is reached after 4 circuits.

Examples 6 to 11 The procedure was as described in Examples 4 and 5.
The oils used for deodorization, the internal vessel pressure (mbar) and the temperature of the oil sprayed through the two-component nozzle (superheated steam as the propellent gas) are shown in Table 3 below.
Olfactorily acceptable results are obtained after 4 circuits of the material to be purified.

Table 3 Example Oil type Internal vessel Oil temper-pressure ature (C) (mbar) 6 Rapeseed oil 6 240 7 Peanut oil 5 220 8 Sunflower oil 5 220 g Coconut oil 4 180 Palm oil 6 230 11 Palm kernel oil 6 230 -Example 12 The procedure was as described in Example 1. A
caprylic/capric acid triglyceride prepared as follows was deodorized:
Glycerol is reacted with the C810 fatty acids under normal pressure at 120 to 200C in the presence of a catalyst to form the triester. The esterification reaction is then continued in an increasing vacuum.
Total reaction time approx. 14 hours. After removal of the excess fatty acid in vacuo (10 mbar) at 210C, steaming with nitrogen is carried out under the same operating conditions. The reaction product is cooled, bleached and filtered. Deodorization is then carried out by spraying in superheated steam (two-component nozzle, diameter 0.5 mm, pressure in the deodorizing vessel 5 mbar, superheated steam as the propellent gas) under the following conditions:

Caprylic/capric acid triglyceride:
throughflow 8 kg/h temperature 180C

Superheated steam:
throughflow 7 kg/h temperature 180C
pressure 1 bar After 5 circuits, the process product was odorless.

Examples 13 and 14 The procedure was as described in Example 12. The starting materials to be deodorized are n-butyl stearate (Example 13) and isobutyl stearate (Example 14) respec-tively prepared from C16l8 fatty acid mixtures and n-butanol/isobutanol.

21S71~6~

The starting temperature of the ester to be purifiedand the pressure in the deodorizing vessel (mbar) are set out in Table 4 below.

5 Table 4 Example Ester Temperature of Pressure in the the ester (C) deodorizing vessel (mbar) 13 n-Butyl stearate 210 10 14 Isobutyl stearate 220 4 The process product was odorless after 5 circuits.

Examples 15 to 21 The fatty alcohols and ethoxylated fatty alcohols identified in Table 5 below are deodorized as in Examples 4 to 14 by spraying through a two-component nozzle (superheated steam as the propellent gas) in countercur-rent to the superheated steam additionally introduced.
In Table 5 below, the starting materials to be deodori-zed, their temperature and the working pressure in the deodorizing vessel (mbar) are shown in Table 5 below.
The products were satisfactorily purified after 5 circuits.

Table 5 Ex- Fatty alcohol/ Temperature Pressure ample ethyoxylated fatty alcohol of starting in the deo-material dorizing vessel (mbar) C16 Fatty alcohol 150 10 16 Cl2 Fatty alcohol 100 10 17 C14 Fatty alcohol 120 10 18 C18 Fatty alcohol 170 10 19 C20 Guerbet alcohol 2E0 120 10 C1218 Fatty alcohol 3E0 100 10 21 C16-18 Fatty alcohol 29E0 130 10

Claims (22)

1. A process for intensifying and/or accelerating the distillation-based separation of at least partly organic multicomponent mixtures by steaming with superheated steam under the working pressure to facilitate the removal of steam-volatile components of the starting material, characterized in that a starting material which is liquid under the working conditions is steamed in finely sprayed form, being sprayed with the aid of a propellent gas in the form of superheated steam.

2. A process as claimed in claim 1, characterized in that the liquid phase to be purified is sprayed by multi-component spray nozzles.

3. A process as claimed in claims 1 and 2, character-ized in that the steam is used at temperatures at least 50°C, preferably at least 100°C and, more preferably, at least 150 to 200°C above the boiling temperature of the water under the working pressure of the purification stage.

4. A process as claimed in claims 1 to 3, characterized in that the liquid to be purified is sprayed into a stream of the superheated steam and the liquid and steam phases are subsequently separated from one another.

5. A process as claimed in claims 1 to 4, characterized in that the liquid to be steam-treated is sprayed at a temperature which corresponds at least substantially to the boiling temperature of the water under working conditions.

6. A process as claimed in claims 1 to 5, characterized in that the spray zone is operated under normal pressure or under reduced pressures or even under excess pres-sures, depending on the volatility of the material to be treated and the impurities to be removed.

7. A process as claimed in claims 1 to 6, characterized in that the temperatures of the liquid phase to be purified and the steam to be used are adapted to one another, at least substantially the same temperatures being preferred and a comparatively higher temperature in the superheated steam used being particularly preferred.

8. A process as claimed in claims 1 to 7, characterized in that the steam temperatures are up to about 500°C and preferably in the range from about 100 to 400°C.

9. A process as claimed in claims 1 to 8, characterized in that a substantially water-free material is subjected to the steam treatment.

10. A process as claimed in claims 1 to 8, characterized in that a water-containing material is subjected to the treatment with superheated steam in the spray zone and, if desired, is at least partly dried at the same time.

11. A process as claimed in claims 1 to 8 and 10, characterized in that aqueous solutions, emulsions and/or suspensions of impurity-laden useful materials liquid and/or solid at room temperature or mixtures of such useful materials are subjected to the process, being both steam-treated and also at least partly dried.

12. A process as claimed in claims 1 to 8, 10 and 11, characterized in that aqueous preparations of useful materials solid at the working temperature or mixtures of such useful materials are subjected to combined separa-tion by steam treatment and drying with superheated steam.

13. A process as claimed in claim 12, characterized in that it uses solid useful materials or mixtures of useful materials in the form of a water-containing preparation which are suitable under the working conditions for forming solids with an open-pore internal structure of which the plasticity and surface tackiness are limited to such an extent that the particles and/or the open pores of their internal structure are largely prevented from adhering to one another, even under the conditions of exposure to the superheated steam.

14. A process as claimed in claims 1 to 13, charac-terized in that the useful materials or mixtures of useful materials are processed using water-soluble and/or fine-particle water-insoluble inorganic and/or organic auxiliaries which are preferably solid and non-tacky in their dry state.

15. A process as claimed in claims 1 to 14, charac-terized in that the starting material is subjected to a multiple-stage steam treatment, more particularly to a multiple-stage treatment in finely sprayed form, super-heated steam being used as the propellent gas in at least one stage.

16. A modification of the process claimed in claims 1 to 14, characterized in that an at least substantially water-free material which is liquid under working condi-tions is sprayed into a stream of the superheated steam without the use of the propellent gas.

17. A process as claimed in claim 16, characterized in that the starting material to be purified has a water content of < 10% by weight and preferably < 5% by weight and more preferably < 3% by weight.

18. A process as claimed in claims 1 to 17, charac-terized in that the laden steam phase(s) are freed from the components taken up from the starting material, preferably using membrane separation processes after condensation of the steam phase(s).

19. The use of the process claimed in claims 1 to 18 for the steam treatment and more particularly for the deodor-ization of fats and/or oils for use, for example, as foods, as cosmetics and/or as pharmaceutical auxiliaries and for the recovery of flavorings and concentrated flavorings.

20. The use of the process claimed in claims 1 to 18 for the purification of alkoxylated useful materials and mix-tures of alkoxylated useful materials, more particularly for the removal of impurities, such as unreacted residues of EO, PO or secondary products thereof, such as 1,4-dioxane.

21. The use of the process claimed in claims 1 to 18 as a distillation aid in the separation of at least partly low-volatility mixtures.

22. The use of the process claimed in claims 1 to 18 for improving the purity of useful materials and mixtures of useful materials of vegetable and/or synthetic origin from the field of wetting agents, detergents and/or cleaning products, more particularly for their use in the fields of textile treatment, for example in laundry detergents, cosmetics and/or pharmaceutical auxiliaries.