EP0012687B1 - Process and installation for the extraction of soluble ingredients from raw vegetable materials - Google Patents

Description

The subject of the present invention is a method of treating vegetable raw material, for example seeds, using an extracting agent to extract the principles soluble therein as well as an installation for work of said process.

Various processes and apparatuses are already known for treating plants with the aid of solvents in order to extract the principles soluble therein, according to which the principle of SOXHLET is applied (renewal of the solvent by evaporation of the liquor). extraction).

Thus, according to an extraction device of an improved type, the plants are loaded after having previously cut them so as to obtain a regular and homogeneous loading. A solvent is then introduced into the tank and then stirring is carried out either using a pump or using an agitator in order to promote solid / liquid contacts to allow the extraction of the soluble principles from the plants in the solvent.

After a certain stirring time, the stirring is stopped and the extraction liquor, or miscella, formed by the solvent comprising the soluble principles of the plants is extracted, in particular by filtration. This filtration is for example carried out using a filter floating on the surface of the liquid by which the miscella is sucked under the effect of the vacuum and which accompanies the level of liquid in its descent to the decanted solid mass. Finally, the miscella solvent is evaporated in a separate installation, which makes it possible to obtain an extract containing the soluble principles of said plants.

This operation is repeated several times until the desired degree of exhaustion of the plants is reached, thanks to the solvent originating from the evaporation.

• - la découpe des végétaux, ou de la matière première en général, est réalisée à l'extérieur de la capacité ce qui comporte des risques d'oxydation à l'air libre ;
• - il faut réaliser des immersions et vidanges périodiques- alternées, ce qui donne également lieu à des risques d'aération, tandis que le fonctionnement présente l'inconvénient d'être cyclique ;
• - dans le cas d'agitation du solvant par rapport à la charge solide à l'aide d'une pompe le problème majeur consiste à retenir les matières solides qui sont entraînées ;
• - dans tous les cas, la filtration du miscella ne peut avoir lieu qu'après avoir réalisé une décantation naturelle de la matière solide, ce qui implique l'arrêt de l'agitation, il en résulte que l'opération ne peut être que séquentielle ;
• - même dans le cas de l'emploi d'un filtre flottant, celui-ci présente une surface filtrante limitée par rapport au volume à filtrer puisqu'elle croît en raison du carré du diamètre tandis que le volume de la capacité croît en raison du cube de son diamètre (le diamètre du disque filtrant est légèrement inférieur à celui de la cuve). Il en résulte que les risques de colmatage sont assez importants. D'autre.part, cette situation est aggravée par le fait que ce sont les particules solides les plus fines qui décantent le moins vite et ces particules vont donc constituer en priorité le « gâteau du filtre », ce qui est un facteur de colmatage rapide.

However, this extraction technique is not entirely satisfactory and has various major drawbacks which are the following:

• - The cutting of plants, or of the raw material in general, is carried out outside the capacity, which involves risks of oxidation in the open air;
• - it is necessary to carry out periodic- alternating dumping and emptying, which also gives rise to risks of aeration, while the operation has the drawback of being cyclical;
• - in the case of agitation of the solvent with respect to the solid charge using a pump, the major problem consists in retaining the solid materials which are entrained;
• - in all cases, the filtration of the miscella can only take place after having carried out a natural decantation of the solid matter, which implies stopping the agitation, it follows that the operation can only be sequential ;
• - even in the case of the use of a floating filter, it has a limited filtering surface compared to the volume to be filtered since it increases due to the square of the diameter while the volume of the capacity increases due to the cube of its diameter (the diameter of the filtering disc is slightly smaller than that of the tank). As a result, the risks of clogging are quite significant. On the other hand, this situation is aggravated by the fact that it is the finest solid particles which settle the least quickly and these particles will therefore constitute in priority the “filter cake”, which is a factor of rapid clogging. .

• - l'emploi d'un filtre flottant n'est pas du tout adapté au cas de solides flottants au repos sur un solvant dense ;
• - le solvant est en général évaporé du miscella dans des chaudières discontinues, ce qui présente l'inconvénient majeur de soumettre les principes solubles à l'action de la chaleur pendant un temps relativement long, les principes solubles n'étant obtenus qu'en fin de cycle opératoire. Enfin, le volume de solvant en service est élevé, compte tenu de la capacité de la chaudière de distillation s'ajoutant à celle de l'extraction.

In addition, in the case of the use of this floating filter, the miscella must be sucked through its upper tube which poses serious problems when it comes to solvents with high vapor pressure and in particular hot solvents by the fact that we are going to suck in steam, which gives rise to cavitation effects;

• - the use of a floating filter is not at all suitable for floating solids at rest on a dense solvent;
• the solvent is generally evaporated from the miscella in discontinuous boilers, which has the major drawback of subjecting the soluble principles to the action of heat for a relatively long time, the soluble principles being obtained only at the end of the operating cycle. Finally, the volume of solvent in service is high, taking into account the capacity of the distillation boiler adding to that of the extraction.

In addition, with such known extractors with periodic operation, the supply to the boiler is discontinuous, which requires monitoring and adjustment of the operating conditions (for example sudden variations in level and heating surface).

It should be noted that certain installations include a constant and continuous supply of the evaporating boiler but these conditions are not sufficient to qualify the evaporator as "continuous", insofar as an appreciable volume of miscella (soluble principles + solvent) stays permanently in the heated area of the boiler.

On the other hand, we know from French patent application No. 2388881 of the same inventor an installation the purpose of which is to produce perfumed essential oils from perfume plants by carrying out a rectification of vapors previously emitted from '' a porridge produced by grinding plants.

This correction is obtained by the presence of a distillation column connected to each enclosure so as to collect the vapors emitted from the slurry in combination with an apparatus for condensing the vapors leaving the head of the column to form at least one condensate of essential oils (see the process defined in the claims on pages 14 and 15 and the installation claim 13 on page 16).

Thus, we can see that the installation ante The object of this French patent No. 2,388,881 relates to the extraction of volatile principles by boiling.

It is therefore a distillation process and the action is actually carried out according to a vapor entrainment of the volatile principles, only water being really the adequate agent since it is known that water vapor is the ideal coach.

The concept of recovery at the end of the distillation sequence of the non-volatilized principles is completely annexed to the spirit of this process and of this previous installation.

Thus, in the prior installation and process, the aim is to recover volatile principles whereas in the process and installation which is the subject of the present invention, it is soluble non-volatile principles as the main aim of principles to extract.

The difference in purpose therefore makes it possible to discard this document.

On the other hand, from French patent 1 053938, the use of a filtering wall 5, 6 is known which is used for a different purpose and which constitutes only a technological background of the filtration-extraction installations. Likewise French patent n ° 1 395 067 BERNARDINI describes an automatic unclogging filter which does not constitute an extraction device proper while the unclogging is carried out mainly by the rotation of the filtering elements whereas according to the present invention the latter is constantly ensured by the very turbulence of the extraction medium.

Thus, the solutions of the prior art are not able to solve the specific technical problem posed by a rapid obtaining of the soluble principles of a raw material.

The present invention therefore aims to eliminate the aforementioned drawbacks by providing a solution which makes it possible to quickly obtain the soluble principles of a raw material, in particular a plant or a part thereof, for example its seeds, from the start of the extraction operation while avoiding the preferential paths of the extraction agent in the mass to be extracted, said solution also making it possible to significantly improve the solid / liquid contacts, the separation of the miscella from solids and finally the separation of the soluble principles from the extractant. Preferably, this solution should be of simple design.

This solution consists, according to the present invention, in a process for treating vegetable raw material, for example seeds, using an extracting agent to extract the principles soluble therein, according to which the raw material in bulk in the extractant; vigorous stirring and / or grinding of the raw material is carried out in order to disperse it in the extracting agent and to dissolve the soluble principles of the raw material therein to thereby form a miscella, characterized in that substantially simultaneously at said stirring and grinding, the miscella is filtered which is sent to a separation zone in which the miscella is treated to separate from the extraction agent the soluble principles which are collected, possibly the amount of filtered miscella being offset by the charge of virgin extractant.

Advantageously, the aforementioned treatment of miscella is an evaporation treatment by which, after condensation, the extraction agent is obtained as the top fraction and the soluble principles of the raw material, or extracts, as the bottom or tail fraction. .

According to a particular characteristic of this process, the miscella filtration operation is carried out continuously while the virgin extracting agent is loaded continuously in sufficient quantities to compensate for the quantity of filtered miscella, the compensation introduced extraction preferably being at least partially constituted by the extraction agent separated from the miscella which is recycled.

According to yet another characteristic of this process, the hourly rate of renewal in virgin extracting agent is approximately equal to 1.5 to 3 times the initial load of extracting agent, and the ratio by weight of extracting agent / raw material is preferably between 0.5 and 5 and more preferably between 1 and 2.

According to a particularly advantageous characteristic of this process, the filtered miscella can be stored in a storage area provided upstream of the separation area and the extracting agent separated from the miscella can also be stored to form a reserve of 'extraction.

According to yet another particular characteristic of this process, at the end of continuous extraction, the charge of virgin extraction agent is stopped; substantially simultaneously with the stopping of the load of the extracting agent, the stirring and / or grinding of the raw material is stopped, the settling of the raw material is filtered and then, after filtration of the miscella, performs at least one rinsing operation of the raw material comprising the charge of virgin extracting agent, the stirring of the raw material for an adjustable predetermined period of time and, after said period of time, the filtration of the decanted miscella.

As extraction agent, mention may be made of water, any polar or non-polar solvent, alcoholic or not, or mixtures thereof, that is to say any mixture of solvents with one another or with water and at the limit, just water.

The present invention also relates to an installation for the treatment of vegetable raw material, for example seeds, using an extracting agent to extract the principles soluble therein, comprising at least one capacity or tank d 'extraction provided with means for stirring and / or grinding of raw material; means for supplying the raw material, means for withdrawing the raw material ; means for supplying the extraction agent; means for withdrawing the miscella formed by the extracting agent and the principles soluble in the raw material, characterized in that said means for withdrawing the miscella comprises at least one filter disposed at a level for which it is permanently immersed in continuous walking; at least one apparatus for separating the soluble principles from the miscella, comprising an outlet for extracting agent and an outlet for soluble principles which are substantially free of extracting agent.

Advantageously, the separation device comprises at least one device for evaporating the miscella extracting agent and at least one condensing device for condensing the vapors of extracting agent leaving the top of the device. evaporation.

According to a particular characteristic of this installation, the submerged filter comprises a plurality of filter elements arranged on a perforated tube connected to the separation device. Preferably, the perforated tube is arranged substantially horizontally in the capacity and is advantageously mounted on a capacity inspection pad.

According to a particularly advantageous embodiment, the filter elements consist of discs with an approximately lenticular profile, said discs being coaxial with the aforementioned perforated tube. Thus, the perforated tube being arranged horizontally in the container, the filtering surfaces of the discs constituting the filtering elements are vertical, which greatly reduces the risk of clogging, all the more so since there is generally self-decoloration by turbulence. solid / liquid medium, advantageously this installation comprises means for driving the filter in rotation about its longitudinal axis.

According to another characteristic of this installation, it comprises a storage tank for filtered miscella, connected to the capacity and comprising a supply line for miscella of the aforementioned separation device, as well as a storage tank for extraction agent connected to the extraction agent outlet of the aforementioned separation apparatus. Likewise, the capacity may advantageously include a chimney or vent column, preferably with condenser and guard.

Thus, thanks to the method and the installation of the present invention, a very rapid extraction of the soluble principles of the raw material is obtained, from the start of the extraction cycle, that is to say that the putting into operation is very fast and the quality of the extract excellent. In addition, the loading of raw materials is quick since the raw material is loaded in bulk. On the other hand, the operating sequence of the evaporator corresponds to that of the extraction capacity, which allows dead times to be eliminated. In addition, the invention makes it possible to obtain a maximum proportion of the solvent in service in contact with the raw material to be extracted, which results in a substantial saving of heat energy.

Another advantage consists in the possibility of obtaining, according to the present invention, successive fractions of soluble principles or extracts since the recovery of these soluble principles is carried out from the start of the extraction. The invention also makes it possible to extract by emulsification in water, while the ratio of the densities of raw material / soant is indifferent for the implementation of the present invention.

• la figure 1 représente schématiquement un mode de réalisation d'une installation selon l'invention ;
• la figure 2 représente de manière agrandie, avec arrachement partiel, les moyens de soutirage du miscella comportant un filtre composé d'éléments filtrants, représentés schématiquement à la figure 1 ;
• la figure 3 représente en élévation et en coupe partielle un élément filtrant du filtre représenté aux figures 1 et 2 ; et
• la figure 4 représente une courbe d'extraction en fonction du temps, le taux d'extraction étant représenté en ordonnées et en pourcentage tandis que le temps est mentionné sur l'axe des abscisses.

Other objects, characteristics and advantages of the present invention will appear more clearly in the light of the explanatory description which follows, given with reference to a currently preferred embodiment of the installation according to the present invention, given simply by way of example. This embodiment is shown in the accompanying drawings, and in which:

• FIG. 1 schematically represents an embodiment of an installation according to the invention;
• 2 shows an enlarged view, with partial cutaway, the means for withdrawing the miscella comprising a filter composed of filter elements, shown schematically in Figure 1;
• 3 shows in elevation and in partial section a filter element of the filter shown in Figures 1 and 2; and
• FIG. 4 represents an extraction curve as a function of time, the extraction rate being represented on the ordinate and in percentage while time is mentioned on the abscissa axis.

Referring to Figure 1, an installation according to the present invention essentially comprises at least one capacity or extraction tank 1 provided with means for stirring and / or grinding 2 of the raw material; means 3 for supplying the raw material; withdrawal means 4 for the raw material; means 5 for supplying the extraction agent; means 6 for withdrawing the miscella formed by the extraction agent and the soluble principles of the raw material, comprising at least one filter 7 disposed at a level for which it is permanently submerged; at least one device 8 for separating the soluble principles of miscella, comprising an outlet 9, 9a of extracting agent and an outlet 10 of soluble principles or extracts, substantially free of extracting agent.

According to an advantageous characteristic, this installation comprises a storage tank 11 of the miscella filtered at 7, connected by a line 12, comprising for example a pump 13, at capacity 1, and comprising a supply line 14, with for example also a pump 15, of the separation device 8.

According to another characteristic of this installation, it is possible to interpose on the pipe 12 a fine filtration system 16, advantageously produced in duplex to allow alternating cleaning of the filters or of unclogging for example. by external, manual or automatic, periodic or continuous control, in order to eliminate fine solid particles which could have been entrained through the submerged filter 7. This filtration system 16 may include a drain outlet 17. On the other hand, a decantation system 18 can be interposed on the line 12 between the filtration system 16 and the storage tank 11, this decantation system 18 comprising an outlet 19 for water (in particular coming from the humidity of the raw material ) or other fraction separated by settling of the miscella.

According to another particular characteristic of this installation, the separation device 8 comprises at least one evaporation device formed, in the example shown, by a heat exchanger 20 whose heating fluid circuit 21a, 21 is supplied for example in steam or hot water, this heat exchanger 20 being coupled by a pipe 22 to an expansion cyclone 23 whose apex communicates by a column 24 with a condensing device 25 whose outlet is none other than outlet 9 of extraction agent which advantageously communicates, by a pipe 26, with a reserve tank 27 of extraction agent which is connected by a pipe 28 by means of supply 5 of extraction agent in capacity 1.

On the other hand, the expansion cyclone 23 has at its base an outlet of concentrated miscella comprising mainly the soluble principles of the raw material to be extracted, connected by a line 29, in the example shown, to an evaporation device 30 operating under high vacuum and comprising an extraction agent outlet 31 provided with a condenser 32 and a vacuum trap 33 the outlet of which is constituted by the outlet 9a of the extraction agent, this outlet 9a can also be connected to the reserve tank 27, the vacuum being produced by the pipe 34 leading to the trap 33.

On the other hand, the output of the vacuum evaporation apparatus 30 is none other than the output 10 in soluble principles or extracts that are collected.

Line 29 can also include a pipe 35 for recycling concentrate to the heat exchanger 20 and to the expansion cyclone 23.

According to another particularly advantageous characteristic of the present invention, the filter 7 comprises a plurality of filter elements 7a, arranged on a perforated tube 40, with which they communicate, as shown in FIG. 2, said perforated tube 40 being connected to the 'Separation device 8 through line 12. Advantageously, the filter elements 7a are constituted by discs with an approximately lenticular profile, as can be seen. in FIGS. 2 and 3. In FIG. 3, it can be seen that each disc constituting the filter element 7a comprises an outer casing 41, on each side of the disc, constituted by a metallic fabric, preferably stainless, of meshes adapted to the desired fineness of filtration. These envelopes 41 are separated by a separating element 42 comprising shoulders 43 and are fixed to a central part 44 comprising orifices 45 for communication with the perforated tube 40. The external part of the envelopes 41 is held in a crimp 46 so as to give a V-shaped profile whose tip is directed towards the outside of the disc 7a.

According to an advantageous characteristic, the perforated tube 40 is disposed substantially horizontally in the capacity 1 and is preferably mounted on a buffer 47 for inspecting the capacity 1. On the other hand, this installation advantageously comprises means 48 for driving in rotation of the filter 7 around its longitudinal axis. Of course, to allow this rotational movement of the filter 7, the installation includes various bearing 49 and connection 50 systems allowing the rotation of the perforated tube 40 relative to the inspection pad 47 and therefore to the capacity 1 and on the other hand , relative to the pipe 12. The perforated tube 40 comprises for example a pulley 51 driven by a motor, not shown.

It should be noted that in certain cases where the range of the perforated tube 40 is too great, provision is made in capacity 1 for a support system for the free end 40a of the perforated tube 40.

According to another characteristic of this installation, the capacity 1 comprises a chimney or column 52 whose upper end, opposite to the capacity 1, is advantageously connected to a safety condenser 53 preferably comprising a return circuit 54 of the condensates in the chimney 52. This condensate return circuit may include a decantation device 55 making it possible to separate the extraction agent which is collected by a pipe 56 in the reserve tank 27 while this decantation device 55 has an outlet 57 in condensate other than the extraction agent with possibly a recycling line 58 communicating with the circuit 54.

The capacity 1 preferably comprises means 60 for regulating the temperature inside the capacity 1 and / or means 61 for injecting inert gases, or water vapor, inside the capacity 1 The chimney or column 52 may include baffles 59, for example inclined, preventing the entrainment of solid particles. Furthermore, the separation device 8, the storage tanks 11 and reserve 27 as well as the safety condenser 53 can be connected by various pipes 62, 63, 64, 65 to a guard condenser 66 and / or any trap dry or wet ensuring the ventilation of the installation.

The stirring and / or grinding means 2 advantageously comprise a turbo-defibrator or turbo-shredder 67 with a short drive shaft 68 advantageously disposed at the base 1a of the capacity 1, while the capacity 1 may include deflectors 69 antivortex .

A pipe 70 is also provided making the lower part of the capacity 1 communicate with the pipe 12 in order to allow the extraction of the miscella when the latter has a density greater than that of the raw material to be extracted, as well as a pipe 71 for recycling the extracting agent from the reserve tank 27 to the chimney or column 52 via the pipe 58.

It is also possible to provide a line 12b before the storage tank 11, after the decantation system 18, making line 12 communicate with the reserve tank 27 in order to send the filtered extraction agent directly at the end of extraction, especially during rinsing, in the reserve tank 27 because it can be considered that this extraction agent is practically virgin, which avoids subjecting it to the separation device 8. On the other hand, the reserve tank 27 can also include an inlet 26 'for adding fresh extraction agent to the installation.

It should be noted that the filter 7 may consist of a strainer and may be disposed outside of the tank 1, for example inside the pipe 12 or inside a tank interposed on the pipe 12 without modifying the operation of the installation.

It should also be noted that the filter 7 is, in the example shown, advantageously disposed approximately halfway up the capacity 1 so as to be permanently submerged. In general, for the filter 7 to be permanently submerged, it must be placed at a level between a low level corresponding to the maximum level reached by the raw material soaked in extracting agent and a high level corresponding to the filter immersion limit in the extractant. By modifying the number of filter elements 7a and the number of filters 7, it is possible to modify the filtering capacity of the installation at will, as a function of the flow of traffic to be ensured.

• On charge dans la capacité 1 par les moyens d'amenée 3 une quantité prédéterminée de matière première, cette quantité étant par exemple pour un réacteur de 1 000 litres, constituée par 250 kg de tourteaux de colza mis en vrac, ayant environ 12% de principes solubles ou huile. On amène par les moyens d'amenée 5 une quantité prédéterminée d'agent d'extraction, cette quantité étant par exemple constituée de 500 litres d'hexane, de façon à occuper les 3/4 du volume total de la capacité 1. On doit noter qu'on peut aussi bien introduire d'abord l'agent d'extraction puis la matière première. Dans tous les cas, on obtient une charge de matière première en vrac dans l'agent d'extraction.

The operation of this installation described above is as follows with reference more particularly to FIG. 1:

• A capacity of feedstock 3 is loaded into capacity 1 by a predetermined quantity of raw material, this quantity being for example for a 1,000 liter reactor, consisting of 250 kg of rapeseed oil cake put in bulk, having approximately 12% of soluble principles or oil. A predetermined quantity of extracting agent is brought in by the supply means 5, this quantity being for example made up of 500 liters of hexane, so as to occupy 3/4 of the total volume of the capacity 1. One must note that we can also introduce the extraction agent first and then the raw material. In all cases, a charge of raw material in bulk is obtained in the extracting agent.

When the volume of the raw material placed in bulk in the capacity 1 is too large or when the raw material is in very fine or very hard form, partial grinding or dry pre-grinding can be carried out during charging, this is that is, before the introduction of the extractant.

It should be noted that the volume of the extraction agent to be introduced depends on the raw material to be treated. This volume is determined by preliminary tests which have given the minimum ratio of weight of extraction agent / raw material compatible with a very rapid extraction of the soluble principles of the raw material and with an adequate fluidity of the mixture. In general, the extractant / raw material weight ratio is between 0.5 and 5 and preferably between 1 and 2. In practice, the extractant / raw material ratio is advantageously between 1 and 2 when the extraction agent consists of a solvent other than water and is between 2 and 4 when the extraction agent consists of water. In this example, this weight ratio is 1.32, the density of the hexane being equal to 0.66.

After the closing of the supply means 3, the stirring and / or grinding means 2 are started in order to effect vigorous stirring and / or grinding of the raw material in order to disperse it in the extraction agent and dissolving the soluble principles of the raw material therein to thereby form a miscella.

Substantially simultaneously with said stirring and grinding, the miscella is filtered, by the withdrawal means 6 comprising the filter 7 via the line 12, which is sent to the storage tank 11. This miscella is then transmitted through the line 14 and the pump 15 to the separation device 8 where it is heated in the heat exchanger 20 and then expanded in the cyclone 23 where the extraction agent, that is to say in this case hexane, is vaporized and is condensed in the condensing apparatus 25 to then be collected in the reserve tank 27 by the piping 26. The soluble principles of the extracting agent also comprising traces of extracting agent form a concentrate which is sent via line 29 to the high vacuum evaporation apparatus 30 which makes it possible to completely separate the extraction agent via line 31 and optionally send it via line 9a to the reserve tank 27, while the soluble principles of the raw material are that is to say in this case rapeseed oil, are recovered via line 10. Part of the concentrate obtained in the expansion cyclone 23 can be recycled through line 35 to resubmit it to the separation treatment.

Advantageously, the treatment of the miscella in the separation device 8 is carried out continuously, this continuous operation being easy to carry out by virtue of the storage and reserve tanks 11 which act as buffer tanks. On the other hand, the miscella filtration operation by the withdrawal means 6 is also advantageously carried out continuously.

In the latter case, it is preferably continuously charged with virgin extractant in capacity 1 in an amount sufficient to compensate for the quantity of miscella filtered, the extractant preferably being at least partially constituted by extraction agent separate from mis cella which is recycled by the piping 26 in the reserve tank 27. Preferably, the hourly rate of renewal in virgin extracting agent is approximately equal to 1.5 to 3 times the initial load of extracting agent . Thus, in the present case, the hourly rate of renewal in hexane can vary between 750 liters per hour and 1,500 liters per hour. Thus, the hourly evaporative capacity of the separation device 8 is also 1.5 to 3 times the initial charge of extracting agent.

The withdrawal of the miscella and its separation treatment are continued with renewal of the extraction agent until time t _v for which a very rapid extraction of the soluble principles of the raw material is obtained, economically profitable, this time t _{v being} able to correspond for example to an extraction rate of 93% (see Figure 4). In the case of the extraction of 250 kg of rapeseed cake by 500 liters of hexane, this time t _v is of the order of 80 minutes and at this time t _v 27.9 kg of oil has been obtained. rapeseed.

From time t _v , we are at the end of continuous extraction. The charge of virgin extracting agent is then stopped by the supply means 5 and the miscella is substantially completely filtered, by the filter 7, of the raw material, this being made possible by the aforementioned position of the filter 7.

According to a variant, substantially simultaneously with the stopping of the load of extracting agent, the stirring and / or grinding of the raw material is stopped, which makes it possible to settle the raw material and draw off the layer of supernatant extracting agent.

Preferably, after complete filtration of the miscella, at least one rinsing operation of the raw material is carried out comprising a new charge of virgin extracting agent by the supply means 5, the stirring of the raw material by the means 2 during an adjustable predetermined period of time which is for example five minutes and, after said period of time, the miscella is filtered, in particular using the pump 13.

The storage tanks 11 and reserve 27 are particularly useful for this final rinsing phase, which is discontinuous. In continuous extraction they are practically empty.

Finally, after filtration of the miscella, the raw material is heated, either indirectly by the heating means 60, or directly by injection of hot inert gas, or water vapor, inside the capacity 1, to expel the extracting agent remaining in the raw material by column 52. The extracting agent being condensed by the condenser and recovered by line 56 in the reserve tank 27. It should be noted that during this heating operation of the raw material, advantageously simultaneous mixing of the raw material is carried out by the means 2. In this case, the mixing accelerates the removal of the extraction agent and is continued until the pulverulent phase is obtained.

Finally after this rinsing operation (or several rinsing operations if necessary), to extract practically all of the soluble principles, that is to say for example an extraction rate of 96%, the material is withdrawn first by the withdrawal means 4, this operation being advantageously favored by the mixing of the raw material by the means 2. In the present case (FIG. 4), the total duration of the extraction is approximately 100 minutes (tf) , followed by 60 minutes for distillation, for a total of 2.40 hours, which corresponds to 28.8 kg of oil extract.

It should be noted that the presence of column 52 makes it possible to collect the vapors of extracting agent formed during the stirring and / or grinding operation, which constitutes operational safety. Furthermore, the presence of baffles 59 in this column makes it possible to prevent the entrainment of raw material therein. This prevention is favored by a recycling of condensates by the circuit 54 (decanted water) or an injection of water or also by a recycling of extracting agent from the reserve 27 via the pipe 71.

Finally, according to a variant, two capacity 1 can be used in parallel on the storage tank 11, which makes it possible to operate a capacity in continuous extraction, while the other capacity performs the rinsing and final removal operations of the extraction agent, which makes it possible to further increase the efficiency of the installation, for the same capacity of the evaporator.

It should be noted that the temperature of the extracting agent in capacity 1 can be adjusted by two means: the condensation temperature of the recycled virgin extracting agent can be predetermined by simple adjustment of the operating temperature of the condensing apparatus 25 of the separation apparatus 8, or else this extraction temperature can be controlled by heating or cooling the capacity 1 by means 60. On the other hand, in the case of a raw material lighter than the extracting agent, the miscella is withdrawn through line 70 and filtered by the filtration apparatuses 16 which ensure its clarification before sending it to the separation apparatus 8. It should also be noted that this separation apparatus 8 can be constituted by a distillation column or any other apparatus making it possible to separate the principles soluble in the extracting agent from said extracting agent.

The invention makes it possible to achieve a significant reduction in the duration of the extraction cycle, the extraction times being divided by factors between 2 and 4. This is mainly due to the considerable increase and improvement solid / liquid contacts, thanks to the dilation of the raw material and to the turbulence of the particles in the liquid mass produced by means 2, to the increased richness of the miscella in equilibrium with the material to be extracted and to a rapid renewal of the solvent .

On the other hand, we obtain an optimization of the

quantity of the extracts, that is to say of the soluble principles, by a limited residence time in the capacity 1, the soluble principles being produced from the start of the cycle; as well as a residence time in the separation device 8, in particular in the evaporator, reduced to a minimum, thanks to the principle of continuous operation. In addition, the operations are carried out completely away from air and at strictly set temperatures. It is also possible to place the capacity 1 under an atmosphere consisting of inert gas.

Finally, a simple, stable and automatic operation is obtained since the level and the flow rates remain constant throughout the cycle. Ultimately, only the decantation and final removal of the extraction agent require intervention. Thus, the sequences can be fully automated by a programmer by easily adjusting the parameters of the extraction which affect the quality of the extract obtained at 10, constituted mainly by the speed of rotation of the stirring means 2, the contact time stirred in capacity 1 and the extraction temperature in this capacity 1. On the other hand, in the case where the extracting agent is harmless, the cakes can be removed impregnated with extracting agent and the latter it can be removed on another installation, operating discontinuously or continuously.

An equally important advantage of the invention consists in the fact that this continuous operation makes it possible to produce successive fractions of soluble principle or of extracts which is particularly advantageous when these fractions have different compositions or qualities.

The invention applies to any vegetable raw material comprising soluble principles. The invention is also particularly suitable for very divided raw materials, that is to say with a fine, even pulverulent structure, forming plugs or preferential paths for the extraction agent. One can for example extract fatty oils from vegetable seeds. One can also extract oleoresins from spices such as pepper, vanilla, etc ..., one can also extract the concretes from flowers, etc ..., as well as the protein fractions from plants using in the latter case an extractant consisting of water having an adequate pH known in the art. It can also be used to extract pharmacodynamic principles.

Of course, the invention is in no way limited to the embodiment described and shown which has been given only by way of example. This filter or strainer 7 can be rotatably mounted around its longitudinal axis with a scraper blade fixed underneath and permanently on the capacity 1. This filter or strainer 7 can also be mounted telescopically on the capacity 1 so that it can be removed at least partially of the capacity 1 at the start of the grinding of the raw material to avoid damaging it when this raw material is hard. Likewise, the filtering surface of the filter or of the strainer 7 may consist of a winding of metal wire of special profile spot welded on cylinder generators in the case where too large or too hard solids tend to damage the linings. of metallic canvas. The active surface would be reduced in this case, but this reduction can be compensated for by the use of several strainers 7 provided at different levels. In particular, it includes all the means constituting technical equivalents of the means described, as well as their combinations, if these are carried out according to the spirit and implemented in the context of the claims which follow.

Claims (18)

1. Method of processing a vegetable raw material by means of an extracting agent for extracting therefrom the constituents soluble in said agent, said method consisting in : loading the raw material in bulk into the extracting agent ; performing a strong stirring and/or crushing of the raw material for dispersing it within the extracting agent and carrying out the dissolving of the soluble constituents of the raw material therein to thereby form a miscella, characterized in that substantially at the same time as said stirring and crushing, the miscella is filtered and fed to a separation zone wherein the miscella is treated for separating, from the extracting agent, the soluble constituents which are collected, the amount of filtered miscella being possibly compensated for by the batch of pure extracting agent.

2. Method according to claim 1, characterized in that said treatment of the miscella is a treatment through evaporation by means of which after condensation the extracting agent is obtained as a head fraction and the soluble constituents of the raw materials or extracts are obtained as a bottom fraction.

3. Method according to claim 1 or 2, characterized in that the step of filtering the miscella is carried out continuously whereas the pure extracting agent is loaded continuously in an amount sufficient to compensate for the amount of filtered miscella, the admixed compensating extracting agent preferably consisting at least partially of the extracting agent separated from the miscella which is reprocessed.

4. Method according to claim 3, characterized in that the hourly flow rate of renewal of the pure extracting agent is approximatively equal to 1.5 to 3 times the initial batch of extracting agent and the weight ratio of extracting agent to the raw material is preferably between 0.5 and 5 and more, preferably between 1 and 2.

5. Method according to one of the foregoing claims, characterized in that the filtered miscella is stored in a storing zone provided upstream of the separating zone, the extracting agent, separated from the miscella, being also stored to provide a supply of extracting agent.

6. Method according to one of claims 3 to 5, characterized in that at the end of the extraction, the loading of pure extracting agent is discontinued ; substantially at the same time as the discontinuation of the loading of extracting agent, the stirring and/or the crushing of the raw material is stopped, the miscella separated from the raw material is filtered and then subsequent to the filtration of the miscella is carried out at least one step of rinsing the raw material comprising the loading of pure extracting agent, the stirring of the raw material for an adjustable predetermined period of time and after said period of time the filtration of the separated miscella.

7. Method according to claim 6, characterized in that after the filtration of the separated miscella, the raw material is heated to remove the extracting agent remaining therein and a stirring of the raw material is advantageously carried out simultaneously.

8. Plant for treating a vegetable raw material by means of an extracting agent to extract therefrom the constituents soluble in said agent, in particular for carrying out the method according to one of claims 1 to 7, comprising at least one extracting vessel or tank provided with means for stirring and/or crushing the raw material ; means for feeding the raw material ; means tor drawing off the raw material ; means for feeding the extracting agent ; means for drawing off the miscella provided by the extracting agent and the constituents soluble within the raw material, characterized in that said means for drawing off the miscella comprise at least one filter or strainer arranged on a level at which it is permanently immersed ; at least one device for separating soluble constituents from the miscella, including an outlet for the extracting agent and an outlet for the soluble constituents substantially devoid of extracting agent.

9. Plant according to claim 8, characterized in that the filter or strainer comprises a plurality of filtering elements arranged onto and communicating with a perforated tube connected to said separating device.

10. Plant according to claim 9, characterized in that the perforated tube is arranged substantially horizontally within the vessel and is preferably mounted on an inspection cover of the vessel.

11. Plant according to claim 9, characterized in that the perforated tube is arranged outside of the vessel and upstream of said separation device.

12. Plant according to claim 9, 10 or 11, characterized in that the filtering elements consist of discs with an approximatively lenticular profile, said discs being coaxial with said perforated tube.

13. Plant according to claim 8, characterized in that the filtering surface of said filter or strainer may consist of a coil of metal wire with a special profile spot welded onto cylinder generating lines.

14. Plant according to one of claims 9 to 13, characterized in that it comprises means for rotating the filter about its longitudinal axis.

15. Plant according to one of claims 8 to 14, characterized in that the vessel comprises a flue or shaft for venting to the atmosphere.

16. Plant according to claim 15, characterized in that the top end of the flue, opposite to the vessel, is connected to a safety condenser preferably comprising a circuit for returning the condensates into said flue.

17. Plant according to claim 15 or 16, characterized in that it comprises an extracting agent supply tank connected to the outlet of extracting agent from said separating device, said supply tank preferably comprising a duct for recycling the extracting agent to the vessel and/or to the flue for venting to the atmosphere.

18. Plant according to one of claims 8 to 17, characterized in that it comprises a device for finely filtrating the filtered miscella from the vessel, a tank for storing the filtered miscella connected to the vessel and comprising a duct for feeding said separation device with miscella and various separating appliances in particular upstream of the miscella storage tank in the circuit for returning the condensates from the safety condenser.

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