Apparatus for the extraction of constituents by a supercritical fluid or pressurized liquid

An apparatus for the extraction of constituents present in a substance by means of an extraction fluid constituted by a supercritical fluid or a pressurized liquid. According to this apparatus, in an exterior (3) contacting takes place between the substance and the extraction fluid in order to dissolve the constituents in fluid. The fluid leaving the extractor is then treated to separate the extracted constituents. The fluid is expanded at a pressure p.sub.1. Firstly, the less volatile constituents are separated in a liquid-gas separator (41), the separated gas is then liquefied in gas separator-liquefier (13) and the thus liquefied gas is rectified in column (19) to concentrate the extracted constituents in the liquid phase. The extraction fluid can be carbon dioxide gas.

The present invention relates to a process for extracting constituents by 
supercritical fluids or pressurized liquids. 
It more particularly applies to the extraction of the following organic 
constituents. 
essential oils and perfumes of fresh or dry flowers or plants, such as 
lavender, Lavandin, rose, orange flower, jasmine, broom, camomile, mint, 
etc., 
aromas such as those of wine, tobacco, hops, pepper, etc. 
pharmaceutical products, 
alkaloids, e.g. caffeine and nicotine from tobacco, 
natural colorants, and 
greases and fatty substances such as peanuts, rape, sunflower, etc. 
It can also be used for partial water-alcohol separation and for the 
recovery of petroleum residues, e.g. for the separation of asphaltenes 
from heavy hydrocarbons using pentane and for the assisted recovery of 
deposits using methane, nitrogen or carbon dioxide gas. 
Extraction processes using supercritical fluids or pressurized liquids 
consist of using a fluid under adequate pressure and temperature 
conditions to give said fluid an increased dissolving power compared with 
the constituents to be extracted. In the case of supercritical fluids, the 
pressure and temperature conditions are such that the pressure is above 
the critical pressure and the temperature above the critical temperature. 
In the case of pressurized liquids, the pressure and temperature conditions 
are such that the pressure is above or below the critical pressure and the 
temperature below the critical temperature. 
Throughout the remainder of the present text, the term "extraction fluid" 
will means that it is a supercritical fluid or pressurized liquid under 
the afformentioned temperature and pressure conditions. 
The use of supercritical fluids offers certain advantages compared with 
pressurized liquids. Thus, supercritical fluids have a low viscosity and a 
high diffusivity, which leads to high extraction kinetics. However, 
pressurized liquids are sometimes of greater interest, because they 
generally give a more selective extraction and frequently lead to purer 
extracts. However, the extraction yields are generally lower. 
Among the fluids which can be used under supercritical conditions or in the 
form of pressurized liquids, interest is attached to carbon dioxide gas, 
because it is non-toxic and causes no particular problems. Moreover, its 
critical temperature and pressure are not very high, because they 
respectively correspond to 31.degree. C. and 7.3 MPa. It is also of 
interest for application in the medical field, the agroalimentary field 
and the field of perfumes and cosmetics. 
In order to carry out this type of extraction, the substance containing the 
constituents to be extracted is generally introduced into an extractor and 
in the latter is brought into contact with an extraction fluid raised to 
the desired temperature and pressure. On leaving the extractor, the 
extraction fluid consequently contains certain constituents and the latter 
are recovered by expansion of the fluid at atmospheric pressure, which 
makes it possible to collect the extraction fluid in gaseous form and to 
separate the extracted constituents in liquid form. On leaving the 
separator, the gaseous phase is then compressed and raised to the desired 
pressure, followed by cooling to the desired temperature and recycling in 
the extractor. In general, the liquid-gas separator is constituted by a 
cyclone and the gaseous phase leaving the latter may optionally be 
processed on several traps: active carbon, absorbing resins, etc. before 
being recycled into the extractor. This operating procedure is not very 
effective when the constituents to be extracted are highly volatile, 
because the latter cannot be easily collected in liquid form during the 
expansion of the extraction fluid at atmospheric pressure. Thus, during 
said expansion, the velocity of the fluid increases greatly and can, for 
example, pass from 1 cm/s to 250 cm/s on passing from a pressure of 15 MPa 
to 0.1 MPa. This velocity increase leads to the formation of very fine 
aerosols which cannot be separated in the cyclone separator and are 
consequently recycled or discharged with the gaseous effluence. To obviate 
this disadvantage, consideration has been given to the use of two-stage 
expansion. Firstly the fluid is expanded at a pressure intermediate 
between atmospheric pressure and the pressure used inthe extractor, 
followed by the separation of the liquid constituents from the expanded 
gaseous phase, then the gaseous phase is expanded at atmospheric pressure 
and the liquid constituents separated from said gaseous phase in a second 
separator also constituted by a cyclone. This makes it possible to improve 
the result obtained, but in the case of highly volatile constituents the 
extraction levels are not adequate. 
The present invention relates to a process for extracting constituents by 
an extraction fluid constituted by a supercritical fluid or a pressurized 
liquid, which obviates the disadvantages of the aforementioned processes. 
The present invention therefore relates to a process for the extraction of 
at least one constituent present in a substance by means of an extraction 
fluid constituted buy a supercritical fluid or a pressurized liquid 
comprising contacting said substance with said fluid in an extractor at a 
temperature T and a pressure p adequate for dissolving the constituent or 
constituents in said fluid, then separating the constituent or 
constituents extracted in said fluid, characterized in that the separation 
process of said extracted constituent or constituents comprises a first 
stage consisting of expanding the fluid leaving the extractor at a 
pressure p.sub.1 below pressure p, whilst maintaining it at the desired 
temperature to obtain said fluid in the gaseous state and part of said 
extracted constituent or constituents in the liquid state and separating 
the constituent or constituents in the liquid state from said fluid in the 
gaseous state and a second stage consisting of liquefying the fluid in the 
gaseous state separated in this way, rectifying the thus liquefying fluid 
for concentrating the extracted constituent or constituents in the liquid 
phase and treating the liquid phase to recover the constituent or 
constituents by carrying out the liquefaction and rectification operations 
in a gas separator-liquefier linked by its upper part with a vertical 
column surmounted by a condenser, so as to wash the gaseous phase 
discharged by said column by means of the condensed fluid. 
By carrying out in accordance with the invention a concentration of the 
extracted constituents in a liquid phase, there is not loss of volatile 
products which would occur according to the prior art at the time of 
liquid-gas separation by entrainments of certain products in the form of 
aerosols in the gaseous flow. 
Moreover, it is easy to recover these concentrated constituents in the 
liquid phase by subjecting the latter to an evaporation for vaporizing the 
fluid contained therein and thus solely recovering the constituents in the 
liquid state. The liquefied phase rectification operation is preferably 
performed by raising to a slightly higher temperature the upper layer of 
the liquefied phase present in said separator-liquefier. 
By carrying out in accordance with the invention a first separation stage 
of the extracted constituents, there is an improvement to the efficiency 
of the separation by firstly recovering the less volatile constituents 
following expansion at pressure p.sub.1 and then recovering after 
rectification the more volatile constituents, which concentrate in the 
liquid phase during the rectification operation. The rectification 
operation can be performed at a pressure p.sub.2 below pressure p.sub.1 
used for the expansion, but generally rectification is carried out at the 
same pressure as that usef for the expansion of the extraction fluid. 
The process according to the invention can also apply to continuously 
functioning extraction installations, i.e. installations in which the 
fluid is continuously circulated in the extractor, the extracted 
constituents then being recovered in the fluid and the fluid is then 
recycled into the extractor after bringing it to the extraction pressure p 
and temperature T conditions. 
Under these conditions, the process can comprise a first continuous 
extraction and separation phase of the constituent or constituents, which 
consists of expanding the fluid leaving the extractor at a pressure 
p.sub.1 below the extraction pressure p, whilst maintaining it at the 
desired temperature to obtain said fluid in the gaseous state and part of 
said constituent or constituents in the liquid state, then separating said 
fluid in the gaseous state from the constituent or constituents in the 
liquid state and recycling into the extractor the thus separated fluid in 
the gaseous state, after bringing it to the extraction pressure p and 
temperature T conditions and a second final stage, in which all the fluid 
circulating in the extractor is treated to recover the constituent or 
constituents contained therein. This second phase consists of subjecting 
all the fluids circulated in the extractor to the two-stage separation 
process described hereinbefore, which comprises a first stage of expanding 
the fluid leaving the extractor at a pressure p.sub.1 below the extraction 
pressure, whilst maintaining it at the desired temperature to obtain said 
fluid in the gaseous state and part of the constituent or constituents in 
the liquid state, separating said fluid in the gaseous state from the 
constituent or constituents in the liquid state and a second stage 
consisting of liquefying the fluid in the gaseous state separated in this 
way, rectifying the thus liquefied fluid for concentrating in the liquid 
phase the remaining extracted constituent or constituents and recovering 
the latter in said liquid phase. 
This makes it possible to continuously extract the less volatile 
constituents, which easily separate from the fluid in the gaseous state 
during expansion at pressure p.sub.1 and at the end of the operation 
recover the more volatile constituents by concentrating them in the liquid 
phase during the liquefaction-rectification operation. 
In the process according to the invention, the extraction fluid is chosen 
as a function of the constituents to be extracted and the temperature and 
pressure conditions necessary for obtaining the dissolving of the 
constituents to be extracted. 
As has been seen hereinbefore, the extraction fluid can be constituted by a 
supercritical fluid or a pressurized liquid. Preference is given to the 
use of a supercritical fluid, i.e. operating at a temperature T above the 
critical temperature and at a pressure p above the critical pressure. 
For example, the extraction fluid can be constituted by carbon dioxide gas 
CO.sub.2, water, n-pentane, chlorotrifluoro methane and sulphur 
hexafluoride. Generally carbon dioxide gas CO.sub.2 is used, because its 
critical temperatue and pressure are not too high. 
If carbon dioxide gas is used as the extraction fluid, pressure p.sub.1 is 
generally in the range 3 to 6 MPa. 
The invention also relates to an apparatus for the extraction of at least 
one of the constituents present in a substance by means of an extraction 
fluid constituted by a supercritical fluid or a pressurized liquid, 
comprising an extractor within which can be placed said substance, means 
for circulating the extraction fluid in said extractor under pressure p 
and temperature T conditions adequate for dissolving the constituent or 
constituents of the substance in said fluid and a discharge pipe for the 
extraction fluid leaving the extractor equipped with a relief valve and 
characterized in that said pipe is connected to the lower part of a gas 
separator-liquefier provided with cooling means linked by its upper part 
with a vertical column surmounted by a condenser, said gas 
separator-liquefier being provided in its lower part with means for 
withdrawing a liquefied phase present in said separator-liquifier and in 
that a gas-liquefier separator is interposes on the gas circuit between 
the relief valve and the gas separator-liquefier. 
Preferably, the condenser located at the upper end of the column is 
surmounted by a heat exchanger makint it possible to raise the gas leaving 
the condenser to a higher temperature. 
Moreover, the cooling means of the gas separator-liquefier make it possible 
to cool the lower part thereof to a lower temperature than the upper part 
thereof. Generally, the gas-liquid separator is a cyclone separator. 
The extraction apparatus according to the invention can be designed to 
continuously extract and separate constituents of a substance by means of 
an extraction fluid treated at the extractor outlet in order to separate 
therefrom part of the extracted constituents and then recycle same in the 
extractor at the desired extraction temperature and pressure. 
According to a first embodiment of an apparatus of this type, it comprises: 
a closed main circuit having in series the extractor, said relief valve, a 
gas-liquid separator and means for recycling the gas leaving said 
separator into said extractor at the extraction temperature T and pressure 
p and a gas separator-liquefier linked by its upper part with a vertical 
column surmounted by a condenser, said gas separator-liquefier being 
branched on to the main circuit by means of a pipe having a valve issuing 
into said main circuit between the gas-liquid separator and said means for 
recycling the gas in the extractor. 
With an apparatus of this type, the more volatile constituents remaining in 
the gaseous phase during the liquid-gas separation are recycled with the 
fluid into the extractor and concentrate in the main circuit. At the end 
of the operation, recovery takes place of the more volatile constituents 
by treating the fluid leaving the extractor in the gas liquefier-separator 
during the emptying of the installation. Thus, at the end of the operation 
it is possible to recover the more volatile constituents, which are often 
the essential constituents for the organoleptic qualities of an aroma or 
perfume. Thus, the absence of a constituent at concentrations of a few 
parts per million often denatures the quality of an aroma or perfume. 
According to a second embodiment of a continuously operating extraction 
apparatus, it comprises: a closed main circuit having in series the 
extractor, said relief valve, the gas-liquid separator and means for 
recycling the gas leaving said separator into said extractor at extraction 
temperature T and pressure p, a gas separator-liquefier linked by its 
upper part with a vertical column surmounted by a condenser means for 
continuously discharging into a container the liquid phase separated in 
said gas-liquid separator and means for connecting the upper part of the 
container to the gas liquefier-separator in order to treat therein the gas 
able to pass from the liquid-gas separator into the container. 
In the case of this apparatus, it is possible to continuously withdraw the 
constituents extracted at the liquid-gas separator and gas 
separator-liquefier is branched at said liquid-gas separator. In this 
case, permanent treatment takes place of an aliquot part of the gas from 
the gas-liquid separator, in order to recover the more volatile 
constituents remaining in the gaseous phase. 
According to a third embodiment of a continuously operating apparatus 
according to the invention, the latter comprises: a closed main circuit 
having in series the extractor, said relief valve, a gas-liquid separator, 
a gas separator-liquefier linked by its upper part with a vertical column 
surmounted by a condenser and means for recycling the gas leaving said 
condenser into the said extractor at the extraction temperature T and 
pressure p, means for discontinuously sampling the liquid phase present in 
the gas separator-liquefier, means for evaporating the sampled liquid 
phase and means for recycling the gas separated during the evaporation of 
the liquid phase sampled in the main circuit between the condenser and the 
means for recycling the gas into the extractor. 
With this arrangement, it is possible to permanently treat the fluid 
leaving the extractor in order to firstly separate the less volatile 
constituents in the liquid-gas separator and then recover the more 
volatile constituents in the gas separator-liquefier. In this case, to 
maintain the fluid quantity circulating in the main circuit at the desired 
value, it is necessary to treat the liquid phase present in the gas 
liquefier in order to separate therefrom the fluid contained therein and 
recycle it into the main circuit.

In FIG. 1, which is the pressure (in MPa)-temperature (in .degree.C.) phase 
diagram of carbon dioxide gas CO.sub.2, it can be seen that the critical 
point of the CO.sub.2 corresponds to a temperature of 31.degree. C. and a 
pressure of 7.3 MPa. In addition, the range within which CO.sub.2 exists 
as a supercritical fluid corresponds to the hatched area A. Outside this 
range, CO.sub.2 can exist in the form of a gas in zone B, in the form of a 
liquid in zone C and in the form of a solid in zone D. The range in which 
CO.sub.2 can exist in the form of a pressurized liquid corresponds to zone 
C. 
On referring now to FIG. 2, which illustrates in a comparative manner an 
extraction installation not according to the invention, it can be seen 
that the latter has in conventional manner an extraction fluid generator 
1, an extractor 3 and a relief valve 5, provided with a heating system for 
maintaining the temperature of the expanded fluid at the desired value. A 
system of lines 7, 9, 11 equipped with valves makes it possible to 
circulate the extraction fluid in the extractor or pass it directly to 
relief valve 5. On leaving the latter, the expanded fluid is directly 
introduced into the gas separator-liquefier 13, which is equipped in its 
lower part with cooling means, constituted by a jacket 15 in which can 
circulate a cooling fluid. The upper part of the separator-liquefier can 
be cooled to a different temperature by circulating a fluid in a coil 17. 
In its upper part, the separator-liquefier is linked with a vertical 
column 19 surmounted by a condenser 21 and a heat exchanger 23. A gas 
discharge pipe 25 connects the gas outlet of the heat exchanger 23 to a 
relief valve 27 also having a heating system to maintain the temperature 
of the expanded fluid at the desired value and a pipe 29 connects the 
relief valve to a gas-liquid separator 31, from which can be extracted the 
liquid phase by pipe 33 having a valve 34, whilst the gaseous effluents 
are discharged by pipe 35. 
In an installation of this type which does not function according to the 
inventive process, the extraction fluid leaving extractor 3 is expanded in 
relief valve 5 at a pressure p.sub.1 and a temperature T.sub.1 
corresponding to zone B of the diagram of FIG. 1, in order to obtain the 
fluid in the gaseous state, which leads to part of the extracted 
constituents being passed into the liquid state, because their solubility 
in the fluid decreases strongly on passing to the gaseous state. This 
gaseous phase is introduced into the gas separator-liquefier 13, which is 
cooled to an adequate temperature to obtain the liquefaction of the gas at 
pressure p.sub.1 and whilst keeping the same pressure one passes from zone 
B to zone C of the diagram of FIG. 1. In this gas liquefier, there is then 
a rectification of the liquefied phase, which makes it possible to 
concentrate the constituents extracted in the liquid phase remaining in 
separator-liquefier 13. Thus, the gaseous phase in equilibrium with the 
liquid phase at the considered temperature and pressure can be discharged 
by the vertical column 19 and partly condensed in condenser 21, which 
makes it possible to wash the gas by the condensed fluid and concentrate 
the extracted products heated in exchanger 23 to prevent obstruction and 
then discharged by pipe 25, expanded to the desired pressure in valve 27 
and the passed to separator 31, in which it is possible to collect the 
residual constituents, which are passed into the liquid state during the 
expansion of the gas in valve 27. 
In order to assist the rectification operation of the liquefied phase in 
the gas separator-liquefier 13, coil 17 is raised to a temperature above 
that of the fluid circulating in jacket 15, in order to aid the 
evaporation of the liquefied phase. Moreover, column 19 preferably has a 
double envelope, so that it can be cooled by fluid circulation between the 
two envelopes. 
In this embodiment, the constituents extracted by the extraction fluid are 
concentrated in the liquid phase, which remains in separator 13. At the 
end of the operation, they are separated from the liquefied phase by 
vaporizing the latter, which makes it possible to recover the constituents 
in the liquid state. They can then be removed by pipe 14. 
FIG. 3 shows an installation according to the invention. The same reference 
numbers are used herein to designate the components of the installation 
common to that shown in FIG. 2. Thus, it can be seen that the only 
difference between the two installations is the introduction of a 
cyclone-type gas-liquid separator 41 on pipe 7 between relief valve 5 and 
the gas separator-liquefier 13. The gas outlet of the liquid-gas separator 
is connected to the separator-liquefier 13 by pipe 12, whilst the 
separated liquid can be discharged by pipe 42. In this case, following the 
expansion of the fluid at the desired pressure and temperature in valve 5, 
part of the extracted constituents which have passed into the liquid state 
during expansion are separated in separator 41 and the liquefaction and 
rectification operations are performed on the gas leaving separator 41. 
The sequence of operations is the same as that described relative to FIG. 
2. 
The following examples illustrate the results obtained with these two 
installations during the extraction of the different constituents of the 
Lavendin solid using supercritical CO.sub.2. 
COMATIVE EXAMPLE 1 
In this example, use is made of the installation shown in FIG. 2 and 293.5 
g of Lavendin solid is introduced in paste form on to the 6 brass plates 
of extractor 3, which have a capacity of 1 liter. Supercritical carbon 
dioxide gas at a temperature of 41.degree. to 42.degree. C., under a 
pressure of approximately 15 MPa is then circulated in extractor 3 at a 
flowrate of approximately 437 g/h. The fluid leaving the extractor is 
expanded in valve 5 at a pressure of 4.7 MPa, whilst being maintained at a 
temperature of 40.degree. C., is then liquefied in the separator-liquefier 
13, which is cooled by circulation of cooling fluid at a temperature of 
2.degree. to 6.degree. C. in jacket 15 and a circulation of water at 
approximately 19.degree. C. in coil 17. In this installation, use is made 
of a double envelope column 19 with an internal diameter of 4 mm, which is 
not lined, has a height of 1 m, which is cooled by a fluid at a 
temperature of 0.degree. to 4.degree. C., whilst also cooling condenser 21 
by a fluid at a temperature of 0.degree. to 4.degree. C. The gas leaving 
condenser 21 has been reheated in exchanger 23 in which circulates a fluid 
at 60.degree. C., then expanded by valve 27 to atmospheric pressure and 
then discharged after passing into separator 31. 
Under these conditions, after operating for 7 hours the extraction 
operation was stopped and the constituents extracted in the 
separator-liquefier 13 by vaporization of the carbon dioxide gas were 
recovered. The extract quantity collected was 109.48 g, which constitutes 
an extraction yield of 37.3%. 
The relative percentages of the different constituents present in the 
starting substance and present in the liquid extract collected in 
separator-liquefier 13 were determined by chromatographic analyis on a 
capillary column. The results are given in the attached tables 1 and 2 for 
benzene and the 13 main constituents classified in rising order of 
volatility. 
These results show that the nett overall yield of constituents other than 
benzene is 36.2% and that the benzene recovery yield, which is the most 
volatile constituent, is 48%. 
EXAMPLE 2 
This example makes use of the installation shown in FIG. 3 with a 0.6 l 
extractor 3 and a 2 m high column 19 lined with balls and 100 g of 
Lavandin solid are placed therein. Supercritical CO.sub.2 is circulated in 
extractor 3 under a pressure of 9.2 to 10.6 MPa and a temperature of 
40.degree. to 48.degree. C. and the fluid leaving the extractor is 
expanded at a pressure p.sub.1 of 4 MPa, whilst keeping its temperature at 
40.degree. C. The latter passes into separator 41, where part of the 
liquid constituents is collected. The gas leaving separator 41 is then 
passed into liquefier 13, where it is cooled by circulation of cooling 
fluid with a temperature of 2.degree. to 6.degree. C. in jacket 15 and 
revaporized in coil 17 heated by water at 19.degree. C. A cooling fluid at 
0.degree. to 4.degree. C. is also circulated in the condenser. Under these 
conditions, after 5.55 hours, 64.72 g of liquid extract is collected in 
separator 41 and 5.13 g of liquid extract in the separator-liquefier 13, 
which represents a total quantity of 69.85 g. 
The weight percentages of the liquid extract in each of the constituents 
were analyzed as hereinbefore. These results are also given in the 
attached tables 1 and 2, where the weight percentages of the constituents 
in the starting product are also shown. 
Determination also took place of the yields of constituents other than 
benzene corresponding to the extracts collected in separator 41 and 
liquefier 13. This reveals a yield of 66.4% of constituents other than 
benzene in cyclone separator 51 and 4.4% of products other than benzene in 
liquefier 13. The total extraction yield for constituents other than 
benzene is consequently 70.8% which constitutes a very marked improvement 
compared with the results obtained with the installation of FIG. 2, where 
it was 36.2%. 
The benzene recover yield is 40%, i.e. substantially identical to that 
obtained in the installation of FIG. 2. 
The benzene content of the liquid extract collected in extractor 41 is 
0.78% and that of the extract collected in liquefier 13 is 16.36%. Thus, 
it can be seen that the separator-liquefier 13 makes it possible to 
recover the more volatile constituents, such as benzene, which are 
difficult to collect in separator 41. 
COMATIVE EXAMPLE 3 
For comparison purposes, the constituents of Lavandin solid were extracted 
in a prior art installation, i.e. in an installation like that of FIG. 2 
solely having the supercritical fluid generator 1, extracter 3, relief 
valve 5 and cyclone separator 41, expansion being effected in valve 5 at 
atmospheric pressure and ambient temperature. 
In the case, 87 g of Lavandin solid paste were placed in extractor 3 and 
underwent extraction by supercritical CO.sub.2 under a pressure of 8 to 10 
MPa and a temperature of 40.degree. to 47.degree. C. After 30 hours 
operation, 28.14 g of liquid extract corresponding to a yield, other than 
benzene, of 35.7% were collected in a separator 41. Analysis of the liquid 
constituents collected in separator 41 and analysis of the starting 
product carried out by capillary column chromatography made it possible to 
determine the percentages of the different constituents in the starting 
product and in the liquid extract. These results are given in tables 1 and 
2. 
These results show that the net overall yield for constituents other than 
benzene is 35.7% and that the benzene recovery yield is very low, namely 
below 0.3%, whilst the recovery yields of .alpha.-pinene, camphene and 
.beta.-pinene are close to zero, because these compounds are absent from 
the chromatographic analysis of the liquid extract. Thus, by carrying out 
in accordance with the invention the expansion of the fluid at a pressure 
intermediate between the critical pressure and atmospheric pressure and 
then liquefying the gaseous phase makes it possible to improve the 
recovery yield of the very volatile products. 
COMATIVE EXAMPLE 4 
This example uses an installation having a supercritical fluid generator 1, 
an extractor 3, a first relief valve 5, a separator 41, a second relief 
valve 27 and a separator 31, i.e. the installation shown in FIG. 3, whilst 
eliminating the separator-liquefier 13. In this case extraction takes 
place with supercritical CO.sub.2 under a pressure of 11.5 to 11.7 MPa and 
a temperature of 43.degree. to 44.degree. C. and the supercritical fluid 
is expanded in valve 5 at a pressure of 3 to 4 MPa at a temperature of 
25.degree. C. Into extractor 3 are introduced 27.66 g of substance in the 
form of a paste and on leaving separator 41 after 22 hours operation, 
13.32 g of constituent are collected. 
Analysis by capillary chromatography of the constituents of the starting 
product and the constituents of the liquid extract collected gave the 
results appearing in tables 1 and 2. These results show that the recovery 
level of constituents other than benzene is 52.2%, but the benzene 
recovery yield is only 6%, whilst the .alpha.-pinene, camphene and 
.beta.-pinene quantities are also low. 
Thus, when the separator-liquefier 13 is not used, the percentage of 
extracted and recovered highly volatile constituents drops considerably. 
The attached table 2 gives the results and operating conditions for 
examples 1 to 4. 
FIGS. 4 to 6 show three embodiments of the extraction installation by 
supercritical fluid or pressurized liquid operating in a continuous manner 
and performing the process for the separation of the constituents 
extracted according to the invention. The same references are used for 
designating the same components which have already been shown in FIGS. 2 
and 3. 
FIG. 4 illustrates a first embodiment of a continuously operating 
installation. It can be seen that it comprises extractor 3, relief valve 5 
and separator 41. It is completed by a liquefier 43, a pump 45 and an 
exchanger 47, which make it possible to recycle into extractor 3 the gas 
leaving separator 41 after having been raised to the extraction pressure p 
and temperature T used in extractor 3. According to the invention, this 
installation also comprises a separator-liquefier 13, which is branched on 
to the main circuit for recycling the fluid into extractor 3 by a pipe 51 
equipped with a valve 53, pipe 51 issuing into the main circuit between 
separator 41 and liquefier 43. 
Extraction takes place in the following way in this installation. In a 
first phase, the extraction fluid is continuously circulated into 
extractor 3 and then after expanding the fluid at pressure p.sub.1 the 
extracted constituents which are passed into the liquid state in cyclone 
separator 41 are separated therefrom. The extracted constituents not 
separated in separator 41 are concentrated in the gas, which is recycled 
into extractor 3 via liquefier 43, pump 45 and exchanger 47. Furthermore, 
at the end of the operation, recovery takes place in a second operating 
phase of the extracted constituents which have not been separated in 
separator 41 using the process according to the invention. To this end, 
all the fluid from the main circuit is passed into liquefier 13. Thus, 
concentration takes place in the liquid phase present in the 
separator-liquefier 13 of the remaining constituents, which are then 
separated from the liquefied gas by vaporization thereof. 
FIG. 5 shows another embodiment, of a continuously functioning installation 
according to the invention. FIG. 5 shows extractor 3, relief valve 5, 
cyclone separator 41, gas liquefier 43, pump 45 and exchanger 47. In the 
case of this particular installation, the pipe 42 for discharging the 
liquid extract from separator 41 and which is equipped with a valve 44 
issues into an extract recovery container 61, provided in its lower part 
with a discharge pipe 63 equipped with a valve 64. Container 61 is 
connected in its upper part by a pipe 65 having a valve 66 to a gas 
separator-liquefier 13, which is kept at a pressure just below pressure 
p.sub.1 of cyclone separator 41. In this case, as valve 44 is open, the 
liquid extract drops into container 61 and the gas which also passes into 
the latter is directed into liquefier 13, where the other extracted 
constituents are separated, as previously. The gas which leaves by pipe 25 
can optionally be treated and then recycled into the main circuit of the 
installation. In this installation, it is necessary to top up the fluid in 
the main circuit, e.g. using pipe 71 to make up the gas losses by pipe 25 
of liquefier 13. 
FIG. 6 shows a third embodiment of a continuous extraction installation 
according to the invention. In this case, the installation also comprises 
a closed main circuit in which are mounted in series extractor 3, relief 
valve 5, cyclone separator 41, gas liquefier 43, recycling pump 45 and 
exchanger 47, the separator-liquefier 13 being interposed on the gas 
circuit between the cyclone separator 41 and gas liquefier 43. 
In this case, the discharge pipe 14 from separator-liquefier 13 issues inot 
an evaporator 71, which can be heated by circulation of a fluid such as 
water in jacket 73. In its upper part, evaporator 71 is connected via a 
pipe 75, provided with a valve 73 to gas liquefier 43. 
In this installation, the expanded fluid from extractor 3 successively 
undergoes liquid-gas separation in separator 41, separation by 
liquefaction and rectification in separator-liquefier 13. The gas leaving 
column 19 is then recycled via liquefier 43, recycling pump 45 and 
exchanger 47 into extractor 3. To maintain the gas quantity circulating in 
the main circuit at the same value, the liquid phase present in the 
separator-liquefier 13 is treated to evaporate the gas contained therein 
and recycle it into the main circuit. To this end, discontinuous 
withdrawal takes place of the liquid phase from liquefier 13 by pipe 14 
and the gas is evaporated in evaporator 71 in order to recycle same by 
pipe 75 into liquefier 43. 
TABLE 1 
__________________________________________________________________________ 
Example 1 Example 2 Example 3 Example 4 
Starting 
Liquid 
Starting 
Liquid 
Starting 
Liquid 
Starting 
Liquid 
Constituents product 
extract 
product 
extract 
product 
extract 
product 
extract 
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% benzene in the starting product and liquid extract 
9.54 12.28 
3.34 17.14 
9.38 0.09 9.54 1.51 
benzene evolution of chromatographic profile of 13 main 
constituents 
.alpha. Pinene 
peak no. 1 
0.21 0.24 0.35 0.39 
0.21 0 0.21 0.10 
Camphene peak no. 2 
0.25 0.28 0.18 0.19 
0.24 0 0.25 0.14 
.beta. Pinene + Sabinene 
peak no. 3 
0.23 0.28 0.24 0.19 
0.04 0 0.23 0.14 
Octanone 3 peak no. 4 
0.60 0.76 0.59 0.56 
0.63 0.20 0.60 0.48 
Cineole 1-8 
peak no. 5 
3.75 4.25 3.53 3.62 
3.87 1.23 3.75 3.03 
Limonene peak no. 6 
1.12 0.83 0.89 0.85 
1.57 0.26 1.12 0.68 
cis .beta. ocimene 
peak no. 7 
1.73 1.95 1.12 1.22 
1.67 0.59 1.73 1.27 
trans .beta. ocimene 
peak no. 8 
1.80 2.07 1.14 1.32 
1.87 0.65 1.80 1.32 
Hexyl acetate 
peak no. 9 
0.42 0.21 0.34 0.36 
0.31 0.27 0.42 0.33 
Linalol peak no. 10 
32.54 30.48 
36.00 36.53 
32.35 31.46 
32.54 31.67 
Camphor peak no. 11 
6.33 6.15 6.36 6.76 
6.19 5.26 6.33 6.10 
Borneol peak no. 12 
3.62 2.36 2.95 3.86 
3.52 3.37 3.62 3.13 
Linalyl acetate 
peak no. 13 
47.41 50.15 
47.33 44.16 
47.54 56.69 
47.41 51.64 
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TABLE 2 
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Ex. 1 Ex. 2 Ex. 3 Ex. 4 
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Supercritical conditons 
Pressure (MPa) 15.5-14.5 
9.2-10.6 
0.8-10 11.5-11.7 
Temperature (.degree.C.) 
41-42 48-40 40-47 44-43 
Seperation conditions 
Pressure (MPa) p.sub.1 = p.sub.2 = 4.7 
p.sub.1 = 4 MPa 
p.sub.1 = 0.1 MPa 
p.sub.1 = 3 to 4 
Temperature (.degree.C.) 
0 to 4.degree. C. in (13) 
1 to 5.degree. C. in (13) 
25.degree. C. 
25.degree. C. 
Time in hours 7.08 2 + 3.55 29.9 22 
% by weight of constituents 
36.2 66.4 in (41) 
35.7 52.2 
recovered; other than benzene 
+ 
4.4 in (13) 
% benzene 
in starting product 
9.54 3.34 9.38 9.54 
in liquid extract 
12.28 0.70 in (41) 
0.088 
1.51 
16.36 in (13) 
Benzene recovery yield (% by weight) 
48 40 .ltoreq.0.3 
6 
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