Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The present invention is concerned with a
proces~ for the extraction of form-labile flowable
masses by means of high pressure extraction, as well
as with a device for carrying out thi~ process.
High pressure extraction i8 a substance separ-
ation process in which a substrate is treated with a
gas, compressed by the use of pressure, as solvent.
The gas is thereby present, depending upon its phase
diagram, in a liquefied or supercritical state and is
thereby characterised by favourable more or less
selective solution and mass transport properties,
depending upon the pressure and temperature conditions
employed. The favourable solution behaviour of gases
compressed in this manner has long since been known
but the commercial use thereof is still in the
development stag~ and is limited to only a few
examples, such as the decaffeination of raw coffee
and the extraction of hops.
The advantages of the high pressure process,
ZO especially in the case of the use of carbon dioxide
as solvent, in comparison with the well-known
extraction methods with benzine fractions or chlorin-
ated hydrocarbons, are sufficiently well known:
carbon dioxide is non-inflammable, is economically
available in large amounts, is physiologically accept-
able, can be easily and completely separated from the
extract and raffinate and does not give rise to any
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environmental problems. In the case of an optimal
carrying out of the process, very valuable products
can immediately be obtained which make subsequent
refining or purification steps totally or partly
superfluous~ In this way, ener~y and process costs
are saved and substance losses due to refining are
avoided~ Therefore, the high pressure process is a
valuable alternative to conventional methods of
extraction.
Processes are already known in which, by the
use of compressed gases in a liquefied or super-
critical state, an extraction of component materials
from natural raw materials is brought about. Thus,
according to Federal Republic of Germany Patent
Specification No. 21 27 611, spice extracts are
obtained from comminuted or chopped vegetable start-
ing material. Federal Republic of Germany Patent
Specification ~o. 27 09 033 describes a process for
the extraction of camomile with supercritical gases.
Federal Republic of Germany Patent Specification ~o.
21 27 596 describes a process for obtaining vegetable
oils in which the fat îs extracted with supercritical
gases, preferably using seeds as raw material. It is
common to these and other processes that the component
materials are obtained from a comminuted raw material
with a solid or form-stable consistency and a large
surface area, the raw material is first placed in an
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extractiOn container and the component materials are
then dissolved out by percolation by a compressed gas
flowing therethrough and then removed. Federal
Republic of Germany Patent Specification No. 14 93 190
describes a proce~s for the separation of liquid and/
or solid mixtures of substances with the help of
supercritical gases. The extraction of liquid
mixtures of substances thereby takes place in such a
manner that the liquid is brought into contact with
the supercritical gas in a mixing step in the manner
of a packed column, this taking up the liquid wholly
or partly. According to another embodiment, a
definite amount of the liquid mixture of substances
to be separated is taken and the gaseous phase is
passed through the liquid in the form of bubbles for
loading thereof. An unlimited growth of the liquid
phase is, if necessary~ to be prevented by special
measures. Federal Republic of Germany Patent
Specification No. 23 32 038 describes a process for
deodorising fatty oils in which these are brought
into contact with the supercritical gas in counter-
current, using a packed column. Federal Republic of
Genmany Patent Specification No. 28 43 430 also des
cribes a process for the treatment of raw~ vegetable
fatty oils in which the ga~ is pumped into the bottom
of an extraction autoclave and the mixture to be
treated is pumped into the top thereof.
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Hitherto, no suitable methods have been known
which permit the use of high pressure extraction for
viscous media, stiff pastes or viscous masses which
are held together by strong internal cohesive forces.
The difficulty in the case of the extraction of
liquid or viscous, non-form-stable media is the pro-
vision of a large internal surface area. For this
purpose, a definite amount of kinetic energy must be
applied, which serves to overcome the surface energy
of the medium to be treated. In the case of media of
low viscosity, where comparatively small cohesive
forces act, under certain circumstances the potential
energy of the medium to be treated itself suffices in
order to provide, in the case of flowing down through
a packed columnt the energy o movement necessary for
the provision of a large surface area. Howeverg this
method can only be used for cases where the substrate
and raffinate display a sufficient liquid consistency.
If the surface area produced is not sufficient and
the column packing provided is not dense enough, there
is a danger that the gas passes by the film of liquid
without being loaded up to the maximum possible
equilibrium concentration. A mere passing through of
the extraction gas through the mediu~ to be treated
also cannot be used universally and is of only low
effectiveness. The introduction of mechanical move-
ment energy in the form of mechanical movement of the
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substrate, for example by means of a stirrer, suffers
from the disadvantage that such means are, under
pressure/ very expensive and require much attention
when used on a technical scale, thus giving rise to
many limitations, for example with regard to the speed
of rotation, the possible extraction pressure which
can be used and the like~ and, by special meansr a
further mechanical transport of the mixture used as
starting material into the separation part o* the
plant thereby brought about must be prevented.
Therefore, it is an object of the present
invention to provide a process for the extraction of
form-labile, flowable ma~se~ in which the above-
mentioned disadvantages do not arise and which can
also be used for the efficient extraction of viscous
and cohesive substrat~s which are held together by
strong internal cohe~ive forces.
Thus, according to the present invention, there
is provided a process for the extraction of form-
labile, flowable masses by high pressure extractionwith a liquefied or ~upercritical gas, wherein load-
ing is carried out in a mixing chamber, the extract-
containing gas is separated in a separation step by
lowering the density and the extract and raffinate
are removed.
The process according to the present invention
can be carried out batchwise or preferably continuously.
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The form-labile, flowable masses can be present,
for example, as molecular-disperse mixture~ ~solutions),
emulsions or dispersions of various components, and
the individual components can be gaseous, liquid or
solid or the extracts or raffinates can be of solid
or liquid consistency. The high pressure extraction
process of the present invention thPreby serves the
purpose of separating desired or undesired components
from the substrate used in the ~ense of obtaining a
carrier material or an extract or a combination of
both possibilities. The mixture used as starting
material can, furthermore, consi~t of a flowable dis-
persion, i.e. of a more or less large amount of finely
divided solid particles which are held together by
adhesive forces in a liquid or viscous matrix.
Furthermore, liquids can be extracted with the process
according to the present invention in a substantially
more effective manner than that according to the prior
art, as well as solid materials which can, as a dust-
ga~ mixture, assume a flowable behaviour. The partic-
ular consistency of the mixture used as starting
material can be changed by adjustment of a particular
temperature within certain limits. The corresponding
temperature is independent of that of the extraction
gas in the loading step and is only limited by ths
solidification point of the material used as 3tarting
material and by its thermal stability.
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We have found that the pressure of the extract-
ion gas can itself be utilised in an outstanding
manner in order to provide the kinetic energy needed
for the production of a large surface area by passing
extraction gas and starting mixture through a mixing
chamber, i.e. loading is carr~ed out in a mixing
chamberO As mixing chamber, there is therehy used a
device appropriate for such a purpose which has
appropriate inlets for tha starting mixture and for
the extraction gas and an outlet for the components
after extraction. For a sufficient extraction~ the
length of the mixing chamber is preferably a multiple
of the breadth or of the diameter of the mixing
chamber, the inlet for the starting mixture and for
the extraction gas being present at one end of the
mixing chamber and the outlet being present at the
other end thereof. The starting mixture (substrate)
and/or the extraction gas are thereby preferably
sprayed into the mixing chamber. In one embodiment,
the direction of flow of the extraction gas can, upon
entering the mixing chamber, be substantially trans-
verse to the direction of flow of the starting mixture
in the case of entry thereof into th~ mixing chamber.
Especially good results are obtained with a
further embodiment in which the starting mixture and
the extraction gas is introduced, in each case, through
one of two nozzles, partly pushed over one anoth~r,
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arranged concentrically in the manner of a "double mixing
nozzle", for example two stainless steel nozzles. With
such an arrangement, there are7 as a rule, achieved better
results than with a mixing chamber in which only the
starting medium is sprayed into the gaseous phase or only
the extraction gas is sprayed into the flowable starting
mixture.
By means of the preferred arrangement according
to the present invention, the pressure of the extraction
gas is converted into velocity, i.e. energy of movement. The
increase of velocity of the flowing compressed gas brought
about by a narrowing of the cross-section corresponds to a
pressure decrease thereof which, depending upon the con-
structional shape of the nozzle, accounts for a more or less
great amount. Consequently, for the extraction, there is
available the pressure of the compressed gas phase produced
by a compressor and reduced by this amount. The pressure
decrease is, as a rule, in comparison with the high extraction
pressures used, of lesser importance and can even, be utilised
in a meaningful way in a special embodiment of the process.
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The invention is illustrated in particular and
preferred embodiments by reference to the accompanying
drawings in which:
FIGURE 1 illustrates a double nozzle mixing arrange-
ment in accordance with one embodiment of the invention,
FIG'JRE 2 illustrates schematically a detail of
the arrangement of Fi gure 1, and
FIGURE 3 illustrates schematically a system for
extraction of form-labile, flowable masses, in accordance
with the invention.
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The flowable substrate is introduced through a
capillary (1) of small internal diameter. It has
thereby been shown that viscous starting media can,
without difficulty, be forced through capillaries of,
for example, only 200 ~m. in~ernal diameter in the
case of appropriate chronological mass throughput
rates. The precise dimensioning of the capillary
depends upon various aspects and can be different in
any particular case. Over the outlet end of this
substrate nozzlel there is concentrically pushed on
a second capillary ~2), the dimensions of the inner
diameter of which are only slightly greater than
those of the outer diameter of the capillary (1), in
~uch a manner that, over a certain path length, w~ich
is preferably not less than 0.3 cm. and is especially
0.5 to 2 cm., there is an overlapping of both capill-
aries. The extraction gas is now introduced in such
a manner that it must hereby flow through the narrow
ring-shaped intermediate space thereby formed between
the inner wall of the outer and the outer wall of the
inner capillary tubee high velocities thereby being
produced. At the point where the inner, substrate-
introducing nozzle ends, there occur strong turbulences
with an irregularly distributed velocity profile. The
masses to be extracted are hereby preferably finely
divided, which results automatically by the turbulence
of the flow which occurs, and flushed over on all sides.
~1 ~51~ ,t:3
Becau~ o t~he intensive mixing and high dissolving
rate connected therewitht the gas-substrate mixture
can, after only a short extraction path within the
capillary (2), be passed directly into a high
pressure container in which the undissolved raffinate
is collected, whereas the gas phase loaded with
extract is passed on further into the separation
part of the plant.
The length of the extraction path depends, in
the first place, upon the velocity of the starting
mixture used and of the velocity and the pressure of
the extraction gas, upon the diameter o the nozzles
and, in the case of a "double mixing nozzle", upon
the mutual ratio of the diameters. Furthermore, it
depends upon the nature of the starting mixture used
and of the extraction gas. The length of the
extraction path is preferably at least 3 cm. and
especially 6 to 10 cm.
In the separation part, there is brought about
the separating out of the dissolved extract in known
manner by lowering the density of the extraction agent.
The regenerated gas is thereafter brought to the
desired extraction state in known manner by compression
and thermostating and can be returned again in the
manner of a cyclic process.
In the preferred embodiment according to the
present invention, the large surface area necessary
~ ~ 5 ~ 0
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for the effective extraction of the flowable substrate
is achieved by a first step or stepwise by the com-
bination of two supplementing working mechanisms
(first and second step). The first step for the
surface area enlargement of the form-labile mass con-
sists in that it is forced through a fine capillary,
a thread-like structure thereby being obtained. The
thread-like mass is then, in a second step, divided
up by the turbulence of the rapidly flowing gas
arising in the outer capillary into very small seg-
ments, whereafter there can be achieved a very
effective, constantly good extraction, ~ithout the
assistance of mechanically moving constructional parts.
The arrangement illustrated in Fig. 1 of the
accompanying drawings is one possible embodiment of
the mixing device preferably used according to the
present invention, which has proved to be very useful
on a pilot plant scale and serves the purpose of
explaining the principle manner of functioning of
the process of the present invention. In Fig. 1,
~1) indicates the nozzle through which the substrate
flows and (2) indicates the nozzle through which the
extraction yas enters, whish nozzle (2) is pushed
over the nozzle (1) and partly overlaps it. Fig. 2
shows a larger individual illustration of the nozzles
(capillaries) (1) and (2). The inner diameter of
nozzle (1) i5, as a ruleO 100 to 1000 ~m., especially
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100 to 400 ~m. The inner diameter of the nozzle ~2)
is, as a rule, only slightly larger dimensioned than
the outer diameter of the nozzle (1~; it is prefer-
ably 250 to ~ 200 ~m~ and especially 250 to 700 ~m.
5 The path length in which the two nozzles (2) and (2)
overlap has the purpose, by cross-sectional narrowing,
partly to convert the pressure of the extraction gas
into velocity, i.e. movement energy. As a rule, the
overlapping length, which is to be as small as possible,
is 0.3 to 4 cm. and especially 0.5 to 2 cm. For the
so-achieved conversion of pressure into movement
energy, the cross-sectional narrowing is, above all,
decisive.
In another embodiment, several such nozzles
can advantageou~ly be arranged in parallel~ One
possibility with a single central gas introduction
is, for example, thereby conceivable in which the
function of the nozzle (2) is performed by a massive
holed plate with fine parallel bores in which, in
each case, the substrate-introducing fine capillaries
(1) are pushed therein a little.
Therefore, the present invention also provides
a mixing device of the above-described type for use
in the extraction process according to the present
invention.
For a more detailed explanation~ Fig~ 3 of the
accompanying drawings illustrates an embodiment of
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the main part of an extraction plant which contai~s,
as components, the mixing and extraction stage
illustrated in Figs. 1 and 2, and which is suitable
for the extraction of viscous media. The pressure
production and regulation, including a gas storage
container, compressor or pump, regulating and closing
valves and the like, are not illustrated since they
are means which are well known from the prior art.
In the same way, an illustration of the known separ-
ation part tone and multi-stage) of the high pressure
plant with subsequent gas recycling are also omitted.
From a compressor, compressed gas passes vla
closure valve VI into the plant and there exerts,
on the one hand, possibly via a movable piston, a
pressure on the substrate to be extracted, which i9
present in an autoclave Al, possibly constructed in
a thermostable form. On the other hand, gas flows
vla closure valve V2 and heat ~xchanger W, which
determines the extraction temperature T, into the
mixing and extraction stage according to Figs. 1 and
2, becomes loaded with extractable materials and
passes the extract directly vla pressure container A2
and closure valve V5 to the separation part o-f the
plant. The part of the substrate which is not soluble
in the extraction agent and which is called the
raffinate remains in the pressure container A2 and
can be withdrawn therefrom batchwise or continuously
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v~a a closure valve V4 on the bottom thereof. Conse-
quentlyO to a certain extent, the autoclave A2
exercises the function of a separator when the
raffinate has not been taken up by the solvent.
For carrying out the process, by opening the
valves Vl and V2, there is first obtained a pre-
determined pressure in the autoclave A2. The valve
V5 is then opened and the desired circulation velocity
of the compressed gas phase is obtained. Subsequently,
the valve V3 is opened so that the entry of the sub-
strate to be extracted present in Al is possible.
In most cases, the described pressure difference
between Al and A2 caused by the nozzle effect, which
is dependent upon the flow velocity of the compressed
gas, suffices in order to bring about the inflow of
the viscous starting mixture. An increased inflow
can be brought about by the incorporation of a
reducing valve RV according to Fig. 3, with the help
of which the small pressure difference present can
be further increased. It has mexely to he observed
that the ratio of the introduced mass stream of
substrate to the introduced mass stream of extraction
agent is such that the compressed gas, corresponding
to its take-up capability caused by the pressure and
temperature, has the possibility of dis~olving the
desired components and thereby of separating them
from the starting mixture used.
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In a variation of Fig. 3, on a technical scale,
the starting mixture used is preferably introduced
continuously with the help of a dosing unit which
can be constructed as a membrane pump or can consist
of two parallel connected long-stroke spindle pumps
which, with the help of a control, are so regulated
that, in each case, one performs the pressure stroke,
whereas the o~her is newly charged for the next
pressure stroke.
With the help of the described device, the
high pre~sure extraction of liquid and viscous media
or of other flowable starting mixtures is possible
in a simple manner, even with a viscous or solid
raffinate phase, which, without the use of a
mechanical stirrer and the investment and operational
costs thereby involved, permits a substantially more
effective mixing and extraction of the starting
material with compreqsed gas than was possible
according to the prior art.
The course of the extraction can thereby not
be compared with the conventional high pressure
processes which normally require an extraction auto-
clave and in which the extraction represents a percol-
ation of the substrate with compressed gases as
solvent. Therefore, this process possesses a
chronological extraction gradient in that, approxi-
mately at the commencement of the extraction~ the gas
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phase is laden with the easier dissolved materials
and, towards the end thereof, with portions of more
sparingly soluble components. At the same time,
initially the extraction conditions corresponding to
the maximum possible loading of the gas phase is
admittedly achieved but, with increasing exhaustion
of the starting mixture, the amount of substances
in the gas phase and thus the efficiency of the pro-
cess decreases. The attempt is often made to compen-
10~ sate this disadvantage by connecting several extractioncontainers one behind the other with differing degrees
of extraction. In contradistinction thereto, in the
case of the process according to the present invention,
an extraction autoclave in the conventional sense is
not used, on the contrary, the loading of the gas
phase takes place in a mixing chamber and preferably
in a small volumed section thereof and especially
within or immediately a~ter the described "double
mixing nozzle". From this results a course of the
extraction which can be conceived as being a chrono-
logical sequence of a plurality of microextractions
of differential small mass portions of the starting
mixture. All microextractions have the same degree
of extraction which is only dependent upon the state
and the dissolving ability of the compressed gas
phase. Therefore, there is obtained an extract phase
which is qualitatively and quantitatively constant
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during the whole course of extraction and which always
corresponds to the maximum degree of working of the
process.
The pressure and temperature of the loading
stage, as well as also of the separation stage, depend
especially upon the liquefied or supercritical gas
used for the extraction and upon the materials to be
extracted. Thus, for the extrac~ion of crude lecithin
with carbon dioxide, there are employed the following
conditionso in the loading stage, it is preferable
to operate at a pressure of from 6Q0 to 1200 and
especially of from 800 to 1000 bar and preferably at
a temperature of from 70 to 150~. and especially of
from 80 to 100C. The pressure of the separation
stage is preferably from 40 to 120 and especially
from 40 to 80 bar and the temperature is preferably
from 30 to 120 C. and preferably from 40 to 80 C.
As extraction gas in a liquefied or super-
critical state, there can, as a rule, be used any gas
known to be useful for high pressure extractions,
whereby there are preferably used harmless, readily
available and cost-favourable gases which do not
impair the environment and, depending upon the nature
and use of the raffinates and extracts, especially
also gases which are unobjectionable from the point
of view of health. Gases which are preferably used
according to the present invention include alkanes
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and alkenes with up to 3 carbon atoms, for example
methane, ethane, propane and ethylene, partly and
completely fluorinated derivatives thereof, for
example mono-, di- and trifluoromethane, mono-, di-,
tri-~ tetra-, penta- and hexafluoroethane and the
like, difluoroethylene, tetrafluoroethylene and the
llke, nitrous oxide, sulphur hexafluoride, argon,
nitrogen and especially carbon dioxide. It is
possible to operate with single gases or also with
a mixture of two or more gases. The gases can bs
used in a supercritical or liquefied state.
As representative examples of the large number
of possibilities of use of the extraction process
according to the present invention, there may be
mentioned the extraction of paraffin jelly for the
separation of cancerogenic accompanying materials,
for example of polycondensed aromatic compounds, the
extraction of wool wax for the removal of pesticides,
polychlorinated hydrocarbons, allergens, free fatty
acids and the like, the extraction of lupinine oil
or the removal of poisonous quinolizidine alkaloids
present therein and the like, and e~pecially the
extraction of crude lecithin.
Using the example of the extraction of crude
lecithin with carbon dioxide~ there is again to be
shown the advantages which can be achieved with the
process according to the present invention in
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comparison with the prior art: From Federal Republic
of Germany Patent Specification No. 30 11 185, there
is known a process for obtaining pure lecithin,
which can be used directly for physiological purposes,
by extraction with supercritical gases. However,
this process is very disadvantageous for the deoiling
of crude lecithin and is practically impossible to
carry out on a technical scale since, even in the case
of a small degree of extraction, the surface of the
crude lecithin present becomes coated with a gum-like
layer which makes any further attack by the super-
critical gas impossible or at least greatly w~akens
its efficiency. According to the present invention,
the extraction of crude lecithin (in one example of
use with viscous substrate (crude lecithin), solid
raffinate (pure lecithin) and liquid extract (fatty
oil)) can, on the other hand, be carried out quickly,
effectively and completely. In Federal Republic of
Germany Patent Specification ~o. 30 11 185, in the
case of using carbon dioxide as extraction agent,
the extraction is carried out at a pressure within
the range of from 72 to 800 bar and preferably of
from 200 to 500 bar and especially of from 300 to
400 bar and at temperatures of from 35 to 80C. and
especially of from 40 to 60 C. According to the
present invention, in a pilot plant there is achieved
a complete and rapid extraction of the crude lecithin,
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which takes place especially well in the pressure
range of from 700 to 1200 bar and at temperatures
above 70C. These extraction conditions according
to the present invention penmit not only a complete
and rapid deoiling of the crude lecithin but, at the
same time, possess the advantage that, together with
the oil, the main amount of the coloured materials
present therein, for example the carotinoids, are
co-extracted so that, as raffinate, there is obtained
a pure lecithin with a very pale colour. The phospho-
lipids themselves are, even at the given high pressure
and temperature values, almost insoluble and are
present only in traces in the intensively dark
coloured extracted oil. The higher temperature
stressing in no way exerts a quality-reducing influence
on the pure lecithin obtained since the increased
temperature is exclusively effective under carbon
dioxide as protective gas atmo~phere. Finally, we
have found that in the case of carrying out the high
pressure extraction according to the process of the
present invention under the given conditions, the
pure lecithin can be obtained directly in a uniform,
powdery and sprinklable form and is, therefore,
directly equal to or better than the previously known
powdered, oil-free lecithin from the po.int of view of
colour as well as of cost. The decisive advantage of
the process according to the present invention consists
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in that, in a single step, starting from the crude
product, there can be directly obtained a deoiled,
pale, sprinklable, highly valuable and directly usable
pure product. Thus, a plurality of process steps is
avoided which, according to the prior art, were
necessary for deoiling, purification, removal of
solvent residueq, drying, pulverising and the like,
in order to obtain a comparable highly valuable pure
product from crude lecithin. Connected with this is
a corresponding reduction of the expenses for apparatus
(investment costs), operating and servicing thereof
(personnel and energy costs), as well as a reduction
of substance losses due to refiningO
The following Examples are given for the purpose
of illustratin~ the present invention. Insofar as i5
not stated to the contrary~ percentages are percentages
by weight~
~.
Use was made of a pilot-plant with the construct-
ion illustrated in Figs. 1, 2 and 3 of the accompanying
drawings. The mixing device was provided with a sub-
strate nozzle (l) of 200 ~m. internal diameter and
450 ~m. outer diameter. The internal diameter of
nozzle (2) was 600 ~m. In the autoclave Al, which was
provided with a movable cylinder but was not thermo~
stated and was at ambient temperature, there were
placed 50 g. crude lecithin. The heat exchanger W,
~ S; ~
the double mixing nozzle, as well as the autoclave A2
were ad]usted to a temperature of 90C. and the
extraction pressure of the carbon dioxide to 920 bar.
The separation of the extract was carried out in one
step at a pressure of 60 bar and at a temperature of
60~. After opening the valve V3, there took place
the introduction of the crude lecithin present within
the course of 1 hour, without any further measures.
After the introduction had taken place, there could
be taken from the autoclave A2 about 32.5 g~ of a
pale, powdery pure lecithin, whereas in the separation
part there were found about 17.5 g. of an almost clear,
intensively yellow coloured oil. The determination of
the lecithin content in the extracted oil gave a value
of 4% which, in part, was caused by the entrainment
effects of the flowing gases in the apparatus used.
The oil content of the crude lecithin used was 35%
and, by means of the extraction, it could be reduced
to a value of only 1~5%. A commercial, pow~ery,
refined and very valuable pure lecithin has, for the
sake of comparison, a residual oil content of 2%.
Fxam~le 2.
The mixing apparatus (FigsO 1 and 2) was equipped
with a substrate nozzle (1) of 105 ~Lm. internal
diameter and 200 ~mO outer diameter. As nozzle (2),
there was used a stainless steel capillary of 260 ~m.
internal diameter. The starting material was a very
~. ~ r
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bitter tasting crude oil from lupin seeds with a
content of ~uinolizidine alkaloids of 2.8%. First,
a definite gas circulation waQ provided, whereby
the carbon dioxide used as extraction agent has, in
the mixing and extraction step, a pressure of 90 bar
and a temperature of 40C. Thereafter, the lupin oil
was dosed in with the help of a liquid membrane pump
via the substrate nozzle (l) into the gas circulation.
In the mixing step, the oil was then intensively
swirled up with the extraction agent so that the free
alkaloid bases contained therein, which were readily
soluble under the chosen conditions, were taken up in
the ga~ phase and, together with a small amount of
other oil components, were transported into the
separation container of the plant. The dissolved
materials were here separated out by decompression
of the carbon dioxide into a gaseous state at 60 bar
and 40C. The greater part of the introduced oil was
advantageously not dissolved in the supercritical gas
but rather passed directly into the autoclave A2, also
at a temperature of 40C., from which it could be
continuously withdrawn again in refined form via the
bottom valve.
During the course of the experiment, 6% of the
introduced crude oil was transported via the gas phase
into the separation container, almost half of this
extract thereby consisting of alkaloids. The main
r.>~3
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amount of 94% was a purified lupin oil which only had
an alkaloid content of 0.05%, as well as an acid
number which was reduced in comparison with the
crude product used as starting material.
