CA1251620A

CA1251620A - Process and device for the extraction of form-labile, flowable masses

Info

Publication number: CA1251620A
Application number: CA000459638A
Authority: CA
Inventors: Egon Stahl; Karl-Werner Quirin; Adalbert Hbgen
Original assignee: SKW Trostberg AG
Current assignee: Evonik Operations GmbH
Priority date: 1983-08-12
Filing date: 1984-07-25
Publication date: 1989-03-28
Also published as: AU564964B2; EP0137214A1; DK341284A; AU3071084A; DK161432B; DE3461508D1; ATE23951T1; EP0137214B1; DK341284D0; DK161432C; JPS6054705A; DE3329249A1

Abstract

ABSTRACT
Process and device for the extraction of form-labile, flowable masses The present invention provides a process for the extraction of form-labile, flowable masses by means of high pressure extraction with a liquefied or supercritical gas, wherein loading is carried out in a mixing chamber, the extract-containing gas is sep-arted in a separation step by lowering the density and the extract and raffinate are removed.
The present invention also provides a mixing device for use in the above extraction process, com-prising two concentrically arranged, partly over-lapping capillaries of differing diameter.

Description

J~ J~

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 ~k 53L~J>

~a 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 ~5~

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.

6'~

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 ,~ -6 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.

~5~
,~

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.

~^5~

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, ~.5~
g 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.

- 9a -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.

~s~

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 =12-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 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 ~ ~5~

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 5 ~

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.

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 vr.d~

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 ..5;~?~

~`i 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 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 ?,, (3 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, 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 x~

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 .~

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 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.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A process for the extraction of a form-labile, flowable mass by means of high pressure extraction with a liquified or supercritical extraction gas, wherein the flowable mass and the extraction gas are introduced into a mixing chamber, in a loading step, through respective nozzles of differing diameter, said nozzles being concen-trically arranged, at least one of said flowable mass and said extraction gas being sprayed into said mixing chamber, the extract-containing gas is separated in a separation step by lowering the density, and the extract and raffinate are removed.

2. A process according to claim 1, wherein both the flowable mass and the extraction gas are sprayed into the mixing chamber.

3. A process according to claim 1, wherein the direc-tion of flow of the extraction gas upon entry into the mixing chamber is transverse to the direction of flow of the flowable mass upon entry into the mixing chamber.

4. A process according to claim 1, wherein the con-centrically arranged nozzles of differing diameter are partly pushed over one another.

5. A process according to claim 1, wherein the flow-able mass is sprayed in through a first nozzle in a second concentric nozzle pushed thereover and partly overlapping the first nozzle, through which second nozzle the extraction gas flows in the same direction as the flowable mass.

6. A process according to claim 1, 2 or 3, wherein, in a part of the mixing chamber or a mixing nozzle on an outlet side of the mixing chamber, there takes place by turbulence an intensive mixing of the gas with the finely divided starting mixture.

7. A process according to claim 1, 2 or 3, wherein at least one of the extract and the raffinate is withdrawn continuously.

8. A process according to claim 1, 2 or 3, wherein the extraction gas is regenerated and again returned to the extraction.

9. A process according to claim 1, 2 or 3, wherein said extraction gas is selected from carbon dioxide, an alkane or alkene with up to 3 carbon atoms, a partly or wholly fluorinated derivative thereof, nitrous oxide, sulphur hexafluoride, argon, nitrogen and a mixture of two or more thereon.

10. A process according to claim 1, wherein for the extraction of crude lecithin with carbon dioxide, opera-tion in the loading step is carried out at a pressure of from 600 to 1200 bar.

11. A process according to claim 10, wherein the load-ing step is carried out at a pressure of from 800 to 1000 bar.

12. A process according to claim 10, wherein the loading step is carried out at a temperature of from 70 to 150°C.

13. A process according to claim 11, wherein the loading step is carried out at a temperature of from 70 to 150°C.

14. A process according to claim 12, wherein the loading step is carried out at a temperature of from 80 to 100°C.

15. A process according to claim 13, wherein the loading step is carried out at a temperature of from 80 to 100°C.

16. A process according to claim 13, 14 or 15, wherein operation in the separation step is carried out at a pressure of from 40 to 120 bar.

17. A process according to claim 13, 14 or 15, wherein operation in the separation step is carried out at a pressure of from 40 to 80 bar.

18. A process according to claim 13, 14 or 15, wherein operation in the separation step is carried out at a temperature of from 30 to 120°C.

19. A process according to claim 13, 14 or 15, wherein operation in the separation step is carried out at a temperature of from 40 to 80°C.

20. A process according to claim 1, wherein crude lecithin is extracted.

21. A process according to claim 13, 14 or 15, wherein carbon dioxide in a supercritical state is used as extraction agent, and operation in the separation step is carried out at a temperature of from 30 to 120°C.

22. A process for the extraction of form-labile flowable masses comprising:
introducing a flowable mass into a mixing chamber, introducing an extraction gas into the mixing chamber at high pressure, said extraction gas being a liquified or supercritical gas, extracting said flowable mass with said extraction gas, separating the extract-containing gas by lowering the density, and removing the extract and raffinate.

23. A process according to claim 22, wherein said flowable mass comprises crude lecithin and said extraction gas is carbon dioxide in a supercritical state.

24. A mixing device for use in the extraction of form-labile, flowable masses comprising two concentrically arranged, partly overlapping capillaries of differing diameter.

25. A mixing device according to claim 24, wherein the internal diameter of the capillary overlapping the other capillary is only slightly greater than the outer diameter of the overlapped capillary.

26. A mixing device according to claim 24 or 25, wherein the internal diameter of the smaller capillary is 100 to 1000 µm.

27. A mixing device according to claim 24 or 25, wherein the internal diameter of the smaller capillary is 100 to 400 µm.

28. A mixing device according to claim 24 or 25, wherein the internal diameter of the larger capillary is from 250 to 1200 µm.

29. A mixing device according to claim 24 or 25, wherein the internal diameter of the larger capillary is from 250 to 700 µm.

30. A mixing device according to claim 24 or 25, wherein the overlapping stretch is 0.3 to 4 cm.

31. A mixing device according to claim 24 or 25, wherein the overlapping stretch is 0.5 to 2 cm.

32. A mixing device according to claim 24 or 25, wherein the larger capillary projects over the outlet end of the smaller capillary by 3 to 15 cm.

33. A mixing device according to claim 24 or 25, wherein the larger capillary projects over the outlet end of the smaller capillary by 6 to 10 cm.

34. A mixing device according to claim 24, wherein it consists of a plurality of overlapping capillaries arranged in parallel.

35. A mixing device according to claim 34, wherein the parallel arranged larger capillaries are formed by a holed plate into the bores of which are inserted the smaller capil-laries.

36. A mixing device for use in the extraction of form-labile, flowable masses comprising:
a first capillary and a second capillary, said second capillary being of greater diameter than said first capillary, and being concentrically disposed in partly overlapping relationship about said first capillary, said first capillary having a first inlet means for flow of a form-labile flowable mass thereinto, said second capillary having a second inlet means for introduction of a liquified or supercritical extraction gas under high pressure thereinto, and separating means for separation of extract-containing gas, and outlet means for removal of the separated extract-containing gas.