WO1994016791A1

WO1994016791A1 - Solvent extraction process and unit and in-line apparatus made of such extraction units, in particular with solvent recovery

Info

Publication number: WO1994016791A1
Application number: PCT/DE1994/000039
Authority: WO
Inventors: Witoslaw Wenta
Original assignee: C. Gerhardt Fabrik Und Lager Chemischer Apparate Gmbh & Co. Kg
Priority date: 1993-01-20
Filing date: 1994-01-17
Publication date: 1994-08-04
Also published as: DE4301343C2; DE4301343A1

Abstract

A solvent extraction process and unit (1a) are used to determine a constituent to be extracted from a sample. The sample is boiled in the extraction unit, together with the solvent, while a liquid extraction is carried out. A vapour extraction above the liquid level of the extraction solvent is then carried out. The evaporated extraction solvent which condenses at the water cooler (5) is later collected in an overflow unit (7) with a collecting chamber (13) and flows outwards into a solvent collecting container (10) for recovery purposes. Such a level reduction of the solvent may also be carried out to effet a change from liquid to vapour extraction. It is known to keep open the outlet (8) of the overflow unit by means of an outer regulating valve and a timing programmer until the desired solvent level is reached by a continuous sinking process. The discharged amounts of extraction solvent are however not reproducible, they may prematurely evaporate and the extracted constituent in the residual amount may vary. The sample container (2) is heated in an inaccurate manner, so that different heat transfer rates lead to different dripping speeds of the condensate. In order to prevent higher error rates of the residual liquid level from setting in, to avoid a premature removal of the sample containers or the admixture of additional extraction solvent, the collecting chamber (13) of the overflow unit, which may be filled with a constant, predetermined volume, is emptied in a quantified manner. The collecting chamber (13) is filled with the generated condensate and emptied several times successively. As it may be rapidly emptied by pressure medium supply or suction effect, known, quantified amounts of solvent are discharged in a predetermined time, so that the resulting residual amounts may be accurately predetermined. This extraction unit is particularly suitable in an in-line apparatus for handling potentially explosive extraction solvents, for example for determining the fat content of a sample.

Description

Name: "Process for solvent extraction and extraction unit therefor, as well as serial device from such extraction units, in particular with solvent recovery"

The present invention relates to a method for solvent extraction using an extraction unit consisting of a sample vessel for receiving the extraction solvent and a sample basket for the sample to be examined, from a heating plate for the sample vessel, and from a water cooler for the rising vapors of the extraction solvent, whereby an upward open overflow unit with a collection space open to the water cooler with a defined limited volume is arranged in a center piece of the extraction unit between the water cooler and the sample vessel above the sample basket, which has an outlet with a drain pipe to one has outer solvent collecting vessel and an inflow or overflow to the sample vessel, and wherein when the overflow unit is closed, the extraction by boiling the sample in the extraction solvent by means of liquid extraction and by additional leaving steam extraction as well as the collection of the solvent for solvent recovery takes place, - and whereby either on the one hand through the drain on the Sequence of the changeover from liquid to steam extraction by lowering the level in the solvent vessel below the. The sample and the changeover to the removal of the collected extraction solvent is carried out, and - in the boiling phase, the rising solvent vapors condense in the water cooler and are completely returned to the sample vessel as condensate in the overflow unit and via their overflow or inflow with the drain closed, as well as in the steam phase the extraction solvent overflows or runs off in the overflow unit, so that the wetted sample is washed out during steam extraction, or that after the boiling phase the sample basket is only adjusted above the liquid level via a longitudinal adjustment device of the extraction solvent is drawn in order to carry out the washing out of the sample in the condensed solvent vapors during the steam extraction, the level then then being reduced.

Such a method and a device for carrying it out is known according to German Patent 37 10 385. A funnel-shaped overflow unit with a drain to an external solvent collecting vessel is then arranged in the center above the sample basket. In the L ^: -.:; ^• ;.; -. Fphase the solvent on the outside of this overflow unit overflows and drips from a tip there onto the sample to be washed out. The vapor phase is set by simply lowering the liquid level below the sample, this being done continuously only by opening and closing an external shut-off valve. The overflow unit has a space that is open to the water cooler and functions as a collecting space. The collection space has a ^' defined known volume, which is limited by the arrangement of the overflow to the sample vessel, and also a drain to the outer solvent collecting vessel. The entire level of the extraction solvent, including the solvent recovery after the steam extraction, is carried out by a continuous outflow process of the vapors of the extraction solvent that collect in the funnel-shaped overflow unit and condense on the water cooler by merely lowering the level of the external barrier to be actuated ¬ or control valve, which is opened via a time program until the solvent level is below the sample, for example during the transition from liquid to vapor extraction. Due to its weight, the extraction solvent runs independently through the open shut-off or control valve into the outer, lower-lying solvent collecting vessel.

During the time for setting the different liquid levels, however, no precisely defined amounts of extraction solvent flow out of the overflow unit into the outer solvent collecting vessel. In particular in the case of a serial device constructed from several extraction units in automated, multi-digit operation, there is a risk that even slight differences in the heating of the sample vessels will result in different residual amounts of extraction solvent. In this respect, there is a risk that the remaining extraction solvent evaporates prematurely, the extracted component (eg fat) oxidizing. Changes in the heating or heat transfer of the different extraction sites lead it to a different dropping rate of the ^{'asserkühler} condensing vapors of the extraction solvent, so that the flow of extraction solvent in the funnel-shaped overflow units in time, either in the same extraction unit reproducible disclosed yet in benach¬ extraction units is equal to.

In a method according to DE 37 10 385 C2, it is necessary to monitor the level of the residual solvent precisely in the 4th extraction phase, in which the residual solvent is recovered, in order to change the extract, e.g. to avoid oxidation of the fat to be extracted. In this respect, when the specified residual amount of the extraction solvent in the sample vessels has been reached, the extraction must be interrupted and the corresponding sample vessels must be removed individually or additional extraction solvent must be added from the outside in order to avoid falsification of the subsequent analysis / weighing.

A precise, reproducible, time-programmed setting and changing of the liquid level in the sample vessel is therefore not possible in the extraction unit according to DE 37 10 385 C2. In this respect, the liquid level must not be changed in such a way that only one control valve is opened via a Zeiprogrammer until the solvent level is below the samples.

According to the Soxtec extraction system, after the boiling phase the sample basket is only removed without lowering the Liquid levels above this with a length adjustment. pulled towards. A simple overflow unit is used, which only serves to collect the solvent to be recovered. During the boiling and steam phase, the extraction solvent drips directly through a lower opening into the sample vessel.

Although both methods run with a "cooking phase" and in the method according to German Patent 37 10 385 an automatic control of the. Given solvent extraction from a controllable outflow from the outside, these two known methods and devices are disadvantageous in that no defined amounts of extraction solvent can be reduced. In automated, multi-digit operation, even slight differences in the heating of the sample vessels can result in different residual amounts of solvent. There is therefore a risk that the remaining extraction solvent will evaporate prematurely, and the extracted fat will burn. In a row device composed of several identical extraction units, these problems multiply in multi-digit operation.

In addition to differences in the heating of the sample vessel heated on the heating plate for the evaporation of the solvent there, there are also different amounts discharged insofar as, due to different wetting and dimensions of the drain pipes to the outer solvent collecting vessel, the flow resistances in the drain pipes differ are and thus from the extraction units even with otherwise identical liquid levels during the opening different amounts of liquid are discharged from the outflow of the overflow unit.

The object of the invention is therefore to provide a method and a device for solvent extraction, in which a change in the extracted part during the lowering and collection of the extraction solvent to be recovered, in particular also in the case of automated extraction units in multi-digit operation, is avoided as. no different residual amounts of solvent are formed.

It should be possible to carry out the individual extraction phases in a time-programmed manner even in multi-digit operation.

To achieve this object, the invention is based on the idea of improving the known methods in such a way that the setting and changing of the liquid level in the sample vessel programs for solvent extraction and / or for lowering the liquid level during the solvent recovery of the extraction solvent, in particular predetermined, repeatable amounts takes place, the residual amounts of the extraction solvent occurring after a certain time being reproducible within narrow limits. It should, in particular, certain ^"residual amounts of the extraction solvent has been present with the extracted part in the sample container after the end of solvent recovery. In this respect, a change in extracted components (eg fats) during the lowering and collection of the extraction solvent to be extracted in automated, multi-digit operation is particularly intended existing series device can be avoided.

To achieve the stated object, a method according to claim 1 is provided in a method of the type mentioned at the outset.

It is essential in this respect that a) to lower the level of the solvent to the level for steam extraction and / or for solvent recovery to the level of the residual solvent amount with the constituent to be extracted contained therein, the extraction solvent evaporates and several equal amounts by repeated complete The filling and emptying of the collecting space of the overflow unit is collected, lowered and passed into the outer solvent collecting vessel until only a predetermined remainder of the extraction solvent with the constituent to be extracted is present in the sample vessel, and b) that the collecting space of the Overflow unit is then emptied for a short time after filling its predetermined defined volume in order to lower the liquid level of the solvent to a remaining amount predetermined at a certain defined point in time, even if the energy supply is imprecise the collecting space also includes the amount of extraction solvent present in the drain pipe to the solvent collecting vessel upstream of a siphon valve or a suction pump, and that c) subsequently or later the residual solvent is evaporated without changing the component then extracted. According to the invention, a new lowering principle is thus used in the transition between the boiling phase and the vapor phase and for collecting the extraction solvent to be recovered in the overflow unit, by arranging one with a collecting space in the sample vessel instead of a mere funnel-shaped overflow unit, which has a defined amount of the evaporation solvent not only can be absorbed, but which can also be repeatedly removed. This amount is collected several times in accordance with the type of solvent and is emptied exactly several times at certain times. For solvent recovery, it is provided that the solvent is only lowered and discharged into the collection container until there is only a residue of preferably 1-2 mm of solvent in the sample vessel. Then, in a remaining evaporation phase, the sample vessel is lifted off the heating plate, for example slightly (5 mm), so that the remaining solvent evaporates without the component to be extracted changing, ie without the fat to be extracted being oxidized, for example. The present invention is therefore based on the idea that an exact lowering of the level can be achieved if a quantized emptying of the overflow unit or of the individual collecting spaces having a predetermined constant volume is possible, and an emptying at certain times, thus takes place in suitably short periods of time, for example by means of a suction or compressed air pulse. Such short emptying times of the extraction solvents present in the collecting rooms with certain predetermined volumes are possible that a different drip rate which arises due to inaccurate energy supply does not fail. has an impact. It is possible that. Limit the error limit with regard to the amount of the remaining amount of the extraction solvent with the extracted constituent (eg fat) in the sample vessel to below + 1 / -1%.

According to the invention, not only must the collecting space open to the water cooler have a defined, limited volume, but the liquid level must be reduced discontinuously, several times with the time required to empty the collecting space, to the level of steam extraction or the residual solvent quantity, between the beginning there are sufficient periods of time for the filling and the subsequent emptying and the emptying takes place only at certain points in time, that is to say in such short-term periods of time that the quantity of the extraction solvent drawn through the collecting space cannot be falsified despite the indefinite supply of energy and heating.

According to claim 2, the control of the short-term emptying of the collecting space takes place in each case by a pressure emptying, a pressure medium being supplied above the overflow unit in the water cooler which is open at the top, or by the suction effect of a pump connected to the outflow of the collecting space, which only works during the discharge of the defined volume of the extraction solvent is effective in the collecting space.

According to claims 3 and 4 there is an exact discharge of the collecting space by means of a compressed air emptying, which is particularly advantageous when handling the present explosion-prone extraction solvent is. This can be carried out in a pulsed manner over the generally relatively short necessary emptying time of the collecting space. The pressure medium or compressed air emptying within the extraction unit thus results in additional controls in order to be able to carry out the individual extraction phases and the solvent recovery precisely.

By means of compressed air, which is introduced into the overflow unit, preferably from above, into the overflow unit, the defined volume of extraction solvent accommodated in the collecting space is pressed through the drain pipe connected to the outlet of the collecting space and leading to the outer solvent collecting vessel. It is preferably provided in this pipe section a U-pipe section of a suitable height, so that the extraction solvent present in the collecting space can be removed without a shut-off valve only during the short supply of compressed air. It is also possible to empty the collecting space by arranging a diaphragm pump in the drain pipe and, for example, by arranging the solvent collecting vessel below the collecting space of the overflow unit and by opening a shut-off valve in the drain pipe.

According to claims 6 and 7, the setting of the different extraction phases, in particular also when using a series device from several extraction units, is carried out at defined times by a time programmer. It is thereby ensured that there are no different residual amounts of extraction solvents in the different extraction units, so that this is at the bottom of the sample vessel Permanent, extracted fat is not oxidized. In this respect, the extraction unit is particularly suitable for determining the fat of a sample.

The device according to claim 9 is used to carry out the method according to the invention for solvent extraction according to the new lowering principle and the new evaporation phase for solvent recovery. Thereafter, during the lowering phase, defined amounts of extraction solvent are used in each case by the overflow unit used with a collecting space through the defined volume of the collecting space after the collection space has been emptied, these being discharged exactly by emptying the collection space in each case. The remaining amount of extraction solvent thus arises exactly according to a previously feasible calculation.

Advantageous designs of the collecting space and the overflow unit as well as their installation within the sample vessel result from the patent claims 10-18.

According to claim 17, the formation of a series device from a plurality of extraction units according to claims 9-16 and 18 is provided.

The method according to the invention for solvent extraction is explained in more detail below with reference to a preferred embodiment of the device for carrying out this method shown in the drawings. The drawings show:

Fig. 1: A longitudinal section through an extraction unit according to a preferred embodiment of the invention, showing a sample vessel mounted on a hot plate with a water cooler arranged above it, and a center piece of the extraction unit arranged between them, in which an opening that opens upwards below the water cooler Overflow unit is arranged, which comes to rest centrally above the sample vessel and the sample basket.

2: A side view of the cylindrical overflow unit with the lower outlet of the extraction unit according to FIG. 1.

3: A longitudinal section through the overflow unit according to section AA of FIG. 2, showing one in the lower half. created collection space, an overflow channel extending laterally therefrom from an overflow to the underside of the overflow unit and a supply space located above the collection space.

4: A top view of the top of the overflow unit according to FIG. 2, showing the inlet openings of the overflow channels, which are arranged over uniform angular sections on a concentric circle around the cylindrical collecting space.

5: A top view of the underside of the overflow unit according to arrow B of Fig. 2; showing the outlets of the overflow channels, which are laterally distributed in a concentric ring around the central drip tip of the underside.

6: The front view of a row device composed of 6 identical extraction units according to FIG. 1, showing a device for lifting the sample vessel from the heating plate.

7: A longitudinal section through a further extraction unit using essential parts according to the extraction unit shown in FIG. 1, the removal of the amount of extraction solvent being triggered not by a compressed air pulse but by a peristaltic pump connected to the outflow of the collecting space .

The extraction unit 1 a shown in FIG. 1 and the extraction units (1 a, b) put together in the series device there in FIG. 6 from 6 identical extraction units consist of a heating plate (4), a sample vessel (2) and sample basket (3) and one Middle piece (6) with built-in cylindrical overflow unit (7) and a water cooler (5). The water cooler (5) is connected to a cooling water circuit via connections (31). A preferred extraction method, in particular for determining the fat content, is described below: To carry out the first extraction phase (liquid extraction), the sample vessel (2) is first filled with solvent up to level I in accordance with FIG. 1, and the sample becomes then entered into the sample basket (3), this over a seal or a conical section of the Middle piece (6) is flanged. The solvent is brought to a boil by heating the solvent with the heating plate (4), the rising solvent vapors condensing from the water cooler (5) and dropping into the cylindrical overflow unit (7). In this boiling phase, the outlet (8) of the overflow unit (7) remains closed, as a result of which the condensate collected rises in the overflow unit (7) and flows out at an overflow (29) into the sample vessel, which flows inside the overflow unit in a step-like manner Overflow web (32) is created at the transition between a lower collecting space (13) and a supply space (21) widening opposite it. The overflow (29) consists of 11 inlet openings (30) which are led to the underside (18) of the overflow unit through overflow channels (19 a, b, c) into the outlet openings there. The cooking phase is controlled by a time programmer (not shown). Part of the fat to be extracted from the sample is boiled and dissolved.

In the second extraction phase, the solvent is lowered from level I to level II by opening drain (8) according to FIG. Since the outlet (8) is created in a lower recess (22) in the bottom part of the collecting space (13), the entire solvent which is found exclusively in the collecting space (13) is removed via the outlet pipe (9) emanating from this outlet (8). the overflow unit is in an outer solvent collecting vessel (10) in the shortest possible, pre-calculated time.

In contrast to the lowering of the solvent according to German Patent No. 37 10 385, in which the overflow unit is designed as a funnel in which not one certain predetermined amount of solvent is collected and in particular no defined amount of solvent is lowered, the overflow unit (7) according to the present invention is designed such that the solvent discharge due to the installation of the overflow only from a predetermined space with a certain defined Volume, namely the collecting space (13) takes place, which is so far made extremely accurate to hold a defined amount of solvent. This amount is then emptied as briefly as possible, depending on the type of solvent.

Emptying takes place by means of a compressed air pulse via a feed line (14) which is arranged in the upper region of the condensation chamber of the water cooler (5). The compressed air flow is directed downwards in the direction of the overflow unit (7) which is open at the top or the collecting space (13) which is also open at the top.

The lowering of the solvent is also controlled in time by a time programmer until the solvent level is below the sample or the sample basket (3). A precisely determined amount of solvent is removed by repeatedly filling and emptying the collecting space (13).

To lower the solvent, there is no need to operate a valve in the drain pipe (9). This is because the drain pipe (9) is only designed with an overflow (15) which lies above the maximum liquid level of the extraction solvent located in the collecting space (13). The overflow (15) is Pipe section formed with a central pipe section above the maximum liquid level. The lateral webs of the U-bend are connected to the drain pipe (9).

In this phase, the extraction solvent has liquid level II, with steam extraction (washing phase) starting. The sample hovers over the boiling solvent in the solvent vapor and is washed out by the condensed pure extraction solvent flowing back from the water cooler.

The extraction solvent overflowing from the overflow channels (19a, b, c ...) drips continuously from the bottom (18) of the overflow unit, which converges in the middle to form a drip tip (22), onto the sample placed in the sample basket (3). This washing phase by steam extraction is also timed using a time programmer.

In a fourth extraction phase, in contrast to German Patent No. 37 10 385, the remaining extraction solvent for recovery is not only evaporated only in a time-programmed manner and passed through the outflow of the overflow unit into the outer solvent collecting vessel.

Rather, in this fourth extraction phase, the solvent to be emptied in the collecting chamber (13) with a certain predetermined volume is in each case completely led outwards into the solvent collecting vessel (10) in such a way that the extraction solvent in the sample vessel (2) has a defined one quantity is lowered, only a certain residue of, for example, 1-2 mm of solvent with the extracted fat being present in the sample vessel (2). (Liquid level III)

In a fifth extraction phase, there is then residual evaporation with reduced energy input through the heating plate (4). For this purpose, the sample vessel (2) is lifted from the heating plate (4) by approx. 5 mm so that the remaining extraction solvent can evaporate without the fat oxidizing.

This lowering of the extraction solvent and evaporation of the remainder of 1-2 mm of extraction solvent present after the fourth extraction phase also takes place with extreme accuracy and is reproducible.

In this respect, in the case of multi-digit operation of the extraction unit in a series device (25) according to FIG. 6, small residual differences in the extraction agent cannot result from small differences in the heating of the sample vessels (2). This ensures that the fat extracted from the sample in the bottom of the sample vessel (2) does not oxidize in all six extraction units.

The structure of the cylindrical overflow unit (9) to be used in the extraction units (la, b) is clearly shown in FIGS. 2-5. The cylindrical overflow unit is made of Teflon, in particular with respect to the design of the collecting space (13), and is turned with extreme accuracy on its outside an upper and lower collar projecting outwards. In the lower collar, the outlet (8) is created, which according to Figure 3 through the side wall (24) Overflow unit is guided by means of a drain hole (23) opening into the bottom part of the collecting space (13).

The overflow unit has a height of approximately 10 cm and a diameter of 6 cm. The collection chamber (13), which is also cylindrical in its lower half, has a height of approximately 3 cm and a diameter of 2.5 cm.

The overflow (29) of the overflow unit (7) to the sample vessel (2) is placed laterally above the collecting space (13). The overflow (29) is formed by an overflow web (32) running laterally above the outer wall of the collecting space and overflow channels (19a, b, c ...) extending to the underside of the overflow unit. According to FIGS. 4 and 5, a total of 11 overflow channels (19a, b, c ...) are created over uniform angular sections on a concentric circle around the cylinder-shaped outer wall of the collecting space (13). An overflow channel is omitted only in the area below the outlet (8) or the Abifußbohrung (23).

In Figure 5 according to the view of arrow B of Figure 2, the underside (18) of the overflow unit is shown. The overflow channels (19a, b, c ...), which are guided parallel to one another in the longitudinal direction of the overflow unit, and their outlet openings can be seen. Furthermore, the drip tip (20) applied in the center of this underside, to which the underside tapers out in a cone.

The arrangement of the overflow channels can also be seen in FIG. 4 in a top view of the overflow unit. These are on the overflow web (32) of the upper one Feed space (21) is created which, like the lower collecting space (13), opens upwards in the direction of the water cooler (15). The bottom part of the collecting space (13) can also be seen, the drain hole (23) of the outlet (18) opening into the recess (22) there leading to the outer solvent collecting vessel which is connected via the drain pipe (9) to the Pipe piece trained overflow is performed.

In FIG. 6, the same extraction units (la, b) are arranged in the series device (25) there. In this time-programmed, the individual extraction and lowering phases I, II, III, IV and V are carried out at the same time, with differences in the heating of the sample vessels and in the outflow through the outflow pipes (9) to the solvent collecting vessel (10) being exact do not impede the uniform lowering of the extraction solvent in the individual extraction units. In this respect, it is impossible for the extracted fat present in the sample vessels (2) to burn.

The two compressed air cylinders (26) on the right and left are used to lift the sample vessels (2) from the heating plate (4), which have a guide rail (27) and thus guide sleeves (28) around the edge of the sample vessels (2) raise and lower.

The extraction method explained on the basis of the extraction unit according to FIGS. 1 - 6 is basically based on the lowering principle according to the invention and the lowering of the solvent to a certain residue and the evaporation of this residue with a reduced output of the heating plates also basically to that mentioned at the beginning Soxtec solvent extraction method applicable.

The devices according to the invention can be used without reservation in the handling of extraction solvents which are at risk of explosion and are still expensive to purchase.

Starting from a liquid level (I) shown in FIG. 1, which is originally the same in all extraction units, which stands above the sample and is formed by a liquid amount of, for example, 150 ml, the liquid level (II) for steam extraction is thus adjusted according to the invention, that the collecting space (13), which has a measuring volume of 15 ml, for example, is emptied three times and filled four times, so that a quantity of liquid of 60 ml is removed from the sample vessel (2). It is possible to carry out the emptying within 3 seconds, while the filling of the collecting space takes place within 4 minutes, assuming that the collecting spaces fill up in 3 1/2 minutes +/- 20 seconds depending on the energy supply. This ensures that the overflow units of all extraction units are completely filled.

The remaining 90 ml of extraction solvent can be removed exactly after the steam extraction has been completed by emptying the collection space seven times after prior filling. In this respect, it is ensured that the same residual amount of extraction solvent is always present in a certain extraction unit after a certain time and thus precise timing and issuing of the heating of the extraction units a serial device is possible. In this respect, it is avoided that the components of the sample to be extracted or those already extracted (eg fats) are changed in the automated multi-digit operation of a series device and that at the end of the extraction different residual amounts of extraction solvents are inadmissibly present in the extraction units.

In this respect, it is no longer necessary to observe the end of the evaporation of the extraction solvent and, if necessary, to add extractant from the outside in order to achieve evaporation in multi-digit operation. The remaining amount of the extraction solvent can be evaporated on the hot plate of the extraction unit even at low power or in a drying cabinet until the extracted components (e.g. fats) have dried. In multi-digit operation, the same removed quantities and residual quantities of extraction solvent result simultaneously at all points, despite different heat supply to the individual extraction points. As a result, determinable amounts of the components to be extracted (e.g. fats) are added to all extraction points at the same time at a previously known point in time, without the risk of decomposition of these components to be quantified and thus of the risk of falsifying the measurement.

In principle, the emptying of the collecting space can take place not only by means of a pulsed compressed air supply by means of compressed air but also by means of argon or nitrogen or other gas mixtures which are compatible with the explosive extraction agent for fat extraction. In the present method, precise time control of the overflow, lowering, draining and draining processes of the extraction solvent is possible via siphon valves with electronic control and pneumatic drive.

Since the extraction solvent present in the collecting space of an extraction unit is fed directly into the outer solvent collecting vessel via a suitable overflow or its own pump, so there is no common closing or control valve as in DE 37 10 385 C2 for the If individual processes of different extraction units are used, there is also no danger that extraction solvents flowing from directly connected processes of a particular extraction unit will be pressed in the collecting space of a neighboring extraction unit if the emptying there takes place in short periods, i.e. suddenly for example by a compressed air pulse.

According to the inventive method u. the device according to the invention thus dispenses with the need for an exact flow measurement of discontinuously or continuously concluding amounts of extraction solvent and the regulation of this outflow. It is therefore unnecessary to use devices which can only be used with reservations when handling explosion-hazardous extraction solvents and which are expensive to purchase.

In FIG. 7, an extraction unit (36) is shown schematically in longitudinal section. Representation of the extraction process with the different extraction liquid levels (I), (II) and (III) to be set. in which the emptying of the collecting space (13), which has to be repeated several times, does not take place through a pressure medium supply via the open water cooler but through the suction effect of a hose pump (35). The hose pump (35) is connected to the outlet (8) of the collecting space (13) or the drain pipe (9) there, which is led to the solvent collecting vessel (10). In this respect, the siphon valve with the overflow (15) and the U-pipe section installed in the drain pipe (9) is not used in the extraction unit (la) of FIGS. 1-6. The peristaltic pump (35) has two spaced pump rollers (30) which are rotated by a pump rotor (34) when the pump is switched on, and only during this time in the collecting space and in the intermediate piece of the drain pipe (9) between the pump and remove the extraction solvent from the outlet (8). The peristaltic pump is only operated for a certain time, which is necessary in order to discharge the predetermined amount of extraction solvents in accordance with the filling volume of the collecting space (13). In the case of a collecting device consisting of several extraction units, each individual extraction unit has its own peristaltic pump (35), so that the quantities of liquid in different collecting rooms of the extraction units cannot influence one another when they flow away.

The drain pipe (9) is guided directly from the outlet of the hose pump (35) into the solvent collecting vessel (10). The peristaltic pump (35) automatically represents a block for the outflow of the extraction solvent in the collecting space (13), provided the peristaltic pump is not in operation. la, lb, extraction units 33 pump roller

2 sample vessel 34 pump rotor

3 sample basket ³⁵ peristaltic pump

4 heating plate ³⁶ extraction unit

5 water coolers

6 center piece

7 overflow unit

8 process

9 drain pipe

10 solvent collecting vessel

11 Inflow from overflow unit to the sample vessel

12 Liquid level in the sample vessel

13 Overflow unit collecting area

14 Supply line for compressed air pulse

15 Overflow in the drain pipe

16 U-pipe section in the drain pipe

17 inner wall of the center piece

18 Bottom of the overflow unit

19a, b, c ... overflow channels in the overflow unit

20 drip tip on the underside of the overflow unit

21 Zύführungsraum in the overflow unit

22 Deepening in the bottom part of the collecting room

23 drain hole running out there in the wall of the overflow unit

24 side wall of the overflow unit

25 series device from several identical extraction units

26 compressed air cylinders

27 guide rail for lifting the extraction unit from the heating plate

28 guide sleeve on the edge of the sample vessel for lifting the extraction unit

29 Overflow on the side above the collecting area

30 inlet openings

31 connections for cooling water circuit

32 overflow web of the overflow (29)

Claims

P a t e n t a n s r u c h e

Process for solvent extraction using an extraction unit consisting of a sample vessel for receiving the extraction solvent and a sample basket for the sample to be examined, a heating plate for the sample vessel, and a water cooler for the rising vapors of the extraction solvent, wherein in a middle piece of the extraction unit between the water cooler and the sample vessel above the sample basket is an upward open overflow unit with a collecting space open to the water cooler with a defined limited volume is arranged, which has a drain with a drain pipe to an outer solvent collecting vessel and an inflow or

Has overflow to the sample vessel, and wherein with the drain of the overflow unit closed, the extraction by boiling the sample in the extraction solvent by means of liquid extraction and subsequent steam extraction and the collection of the extraction solvent for its recovery takes place, and either on the one hand the outflow via the outlet, the changeover from liquid to steam extraction takes place by lowering the level in the solvent vessel below the sample and removing the collected extraction solvent, and in the boiling phase the rising solvent Vapors condense in the water cooler and condensate coming into the overflow unit and via its overflow or inflow with the drain closed is completely returned to the sample vessel, and in the vapor phase the extraction solvent overflows or drains in the overflow unit when the drain is closed again, so that the wetted sample is washed out during the steam extraction, or on the other hand, after the boiling phase, the sample basket is only pulled over the liquid level of the extraction solvent by means of a longitudinal adjustment device in order to carry out the steam extraction, otherwise adjusting and changing the Liquid levels for steam extraction or for lowering the liquid level for solvent recovery, the extraction solvent is lowered and passed over the emptying of the overflow unit into an outer solvent collecting vessel until only the desired level or a residue of the extraction solvent with the constituent (fat) to be extracted is still present in the sample vessel, characterized in that the collecting space is filled with solvent several times in accordance with the predetermined volume and is then emptied at a certain point in time, in order to define the liquid level of the solvent in order to reduce this volume several times, and the remaining solvent evaporation takes place without changing the constituent to be extracted and that when the extraction unit is used the sample vessel is lifted slightly off the heating plate or its output is switched so that the The rest of the extraction solvent is evaporated and removed in this way.

2. Process for solvent extraction according to claim 1, so that the emptying of the overflow unit is carried out in a time-programmed manner by repeatedly depressurizing the collecting space or several times by a pump connected to the outflow of the collecting space, in each case in accordance with the defined volume of the collecting space.

3. A method for solvent extraction according to claim 2, characterized in that the overflow unit designed as a collecting space with a defined volume is emptied in each case by means of compressed air introduced into the extraction unit, the drain pipe of the overflow unit being guided via an overflow into the solvent collecting vessel, which is designed in the form of a U-pipe section which is guided over the maximum liquid level of the extraction solvent in the collecting space and which is connected laterally upward to the drain pipe or the solvent collecting vessel.

4. A method for solvent extraction according to claim 3, characterized in that the supply of compressed air into the extraction unit by a compressed air pulse conducted in the upper region of the condensation chamber of the water cooler takes place, which is directed into the upper opening of the collecting space of the overflow unit.

5. Process for solvent extraction according to claim 1 or 2, so that the outflow of the collecting space is controlled via a check valve arranged in the outflow pipe of the overflow unit and / or a hose or membrane pump connected there.

6. A method for solvent extraction according to one of claims 1-5, characterized in that the time period of emptying the collecting space and the opening and closing of its sequence and the further control of the time period and the times of Umstel¬ treatment of liquid extraction and steam extraction and the level reduction and the solvent recovery is carried out by a time program and at defined times.

7. A method for solvent extraction according to one of claims 1 - 6, characterized in that a plurality of substantially the same extraction units are arranged as series devices, which are each switched for simultaneous solvent extraction at the same time by means of a time programmer and their extraction phases including the solvent evaporation simultaneously and evenly respectively.

Process for solvent extraction according to patent claim 7, characterized in that the individual extraction units of the series device each have an overflow unit, the collecting space of which has the same volume and the same emptying mechanism.

Device for carrying out the method for solvent extraction according to one of the claims 1 - 8, with at least one extraction unit (la, lb, 3 ^" 6) consisting of a sample vessel (2) for receiving the extraction solvent and a sample basket (3) for the Sample to be examined, from a heating plate (4) for the sample vessel (2) and from a between the sample vessel (2) and a water cooler (5) arranged above it in a middle piece (6) of the extraction unit (la, lb, 36) , upward or partially open overflow unit (7), which has a collecting space (13) for receiving a certain amount of solvent with an overflow (29) to the sample vessel (2) and with an outlet (8) and an outlet pipe (9) has an outer solvent collecting vessel (10), and wherein the outlet (8) is assigned a drain pipe (9) with an overflow (15) or with a control valve (35), whereby opening and closing d there overflow (8) of the overflow unit (7) for changing the liquid levels, in particular for changing over from liquid extraction to steam extraction or to solvent recovery by lowering the level of the extraction solvent in the sample vessel (2) below the sample with appropriate removal of the Extraction solution medium proportions in the outer solvent collecting vessel (10) is made possible, characterized in that the storage of the overflow unit (7) and installation of the collecting space (13) takes place in such a way that a certain defined repeatable emptying of the collecting space in single-digit or multi-digit operation for Solvent-collecting vessel (10) is made possible, devices (14.35; 15.16) being provided for emptying the collection space (13) via the outlet (8 ) and a siphon valve (15, 16) by supplying compressed air to the extraction unit (la, lb) from above, or the collecting space (13) of the extraction unit (36) by the flow of one in the drain pipe (9) of the outlet (8) to the solvent Arrange the collecting vessel (10) arranged pump (35) or by other suction there.

10.Device according to claim 9, d a d u r c h g e k e n n z e i c h n t that in the upper open area of the water cooler (5), a feed line (14) is applied with an outer connection for the compressed air generating the emptying pulse.

11.The device according to claim 9 or 10, characterized in that the overflow unit (7) concentrically within the Mittel¬ piece (6) or the water cooler (5) of the extraction unit, connected to the inner wall (17) and with one inwards lowered collecting space is formed, and in the upper area has overflow channels (19a, b, c) open to the side of the upper edge of the collecting chamber (13) to the center of the extraction unit, and an outlet (8) to the solvent collecting vessel (10) in the lower region of the collecting chamber.

12.The device according to one of the claims 9-11, characterized in that the overflow unit (7) with its collecting space (13) in the center piece (6) of the extraction unit (la, lb) is arranged centrally above the sample basket, an overflow (29 ) laterally above the collecting space (13) in the form of the mutually spaced overflow channels (19a, b, e) extending from there to the underside (18) of the overflow unit (7).

13. The device according to claim 12, so that the overflow channels (19a, b, c ...) run out on the underside of the overflow unit into a conical guide surface which forms a central drip tip (20) on the underside (18).

14. The device according to claim 12 or 13, so that the overflow channels (I9a, b, c ...) of the cylindrical collecting space (13) are arranged coaxially around the latter in a lateral distance in an overflow web (32).

15. The device according to one of claims 11-14, characterized in that Above the collecting space (13) the overflow unit (7) has a feed space (21), which is opened upwards in the direction of the water cooler (5) with an expansion.

16. Device according to one of the claims 11-15, characterized in that the drain (8) in the collecting space (13) is created in a recess (22) of the bottom part there, in which a lateral drain hole (23) opens, which through the side wall the overflow unit is guided.

17. Device according to one of the claims 9-16, characterized in that several identical extraction units (la, lb, ...) are arranged to form a series device (25) for multi-digit, simultaneous operation, the collecting spaces (13) of which have the same filling volume and are each connected separately to the same solvent collecting vessel (10) with their respective outlet (8) and drain pipes (9) which are not connected to one another.

18. Device according to one of claims 9-17, characterized in that the individual drains (8) have an overflow arranged in the drain pipe (9), which is formed by a U-pipe section (16), the upper middle piece higher than the overflow web ( 32) is.