Note: Descriptions are shown in the official language in which they were submitted.
2157660
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
21S7660
H 0689 PCT 2
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
2157660
H 0689 PCT 3
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
2157660
H 0689 PCT 4
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-
2157660
H 0689 PCT 5
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
2157660
H 0689 PCT 6
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
H 0689 PCT 7
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
H 0689 PCT 8
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
2157660
H 0689 PCT 9
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~
-
H 0689 PCT 10
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
2157660
H 0689 PCT 11
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~
H 0689 PCT 12
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
21S7660
H 0689 PCT 13
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
H 0689 PCT 14
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
_
H 0689 PCT 15
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
2157660
H 0689 PCT 16
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
H 0689 PCT 17
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~
H 0689 PCT 18
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
21S7660
H 0689 PCT 19
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
- 2157660
-
H 0689 PCT 20
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
21S7660
H 0689 PCT 21
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
2157660
H 0689 PCT 22
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()
H 0689 PCT 23
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
2157660
H 0689 PCT 24
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
2157660
H 0689 PCT 25
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
21S7660
-
H 0689 PCT 26
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
2157660
H 0689 PCT 27
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
H 0689 PCT 28
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
2157660
H 0689 PCT 29
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
2157560
H 0689 PCT 30
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
2157660
-
H 0689 PCT 31
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
H 0689 PCT 33
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
H 0689 PCT 34
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
H 0689 PCT 35
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
21S7660
H 0689 PCT 36
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-
2157660
._
H 0689 PCT 37
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
H 0689 PCT 38
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
- 2157660
-
H 0689 PCT 39
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~
H 0689 PCT 40
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.
2157660
H 0689 PCT 41
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
