JPH0620487B2 - Supercritical fluid extractor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved supercritical fluid extraction device. In particular, it relates to an energy-saving, highly economical supercritical fluid extraction device.

[Prior Art] Extraction utilizing the unique extraction characteristics of a supercritical fluid is
Conventionally, in the extraction tank, the target solute is extracted under the prescribed pressure and temperature conditions, this supercritical fluid is introduced into the separation tank, and the pressure is reduced by the pressure reducing valve or the temperature condition is changed (heating the fluid). (Or cooling), the solubility of the fluid is reduced to separate the solute, and the extraction and separation treatment with a supercritical fluid is performed. In such a processing method, a pump or a compressor is required to circulate or recycle the fluid, or to pressurize or compress the fluid between the extraction tank and the separation tank.

In the present specification, “supercritical fluid extraction” refers to a method of extracting a substance by utilizing the increase of the vapor pressure of the substance and the chemical affinity in the presence of the supercritical fluid. .

[Problems to be Solved by the Invention] Although a supercritical fluid extraction device utilizing the unique extraction characteristics of a supercritical fluid has a wide range of applications, in order to recover the extracted solute under high pressure conditions, Although it is necessary to use an expensive pump or compressor in order to circulate the fluid (gas) between the extraction tank and the separation tank, the present invention utilizes the flow by natural circulation due to the difference in specific gravity and uses these pumps. It is an object to provide an omitted supercritical fluid extraction device.
A further object of the present invention is to provide a device that can simplify the device and save energy by omitting the pumps.

[Means for Solving the Problems] In the supercritical fluid extraction device of the present invention, the temperature dependence of the specific gravity of the fluid in the vicinity of the supercritical point is used to increase the fluid having a low specific gravity and the fluid having a high specific gravity. Is a supercritical fluid extraction device characterized in that the extraction fluid is circulated between the extraction region part for performing the extraction process and the separation region part for performing the separation process by descending natural fluid circulation.
Further, in the supercritical fluid extraction device, the extraction region portion and the separation region portion may be provided in the same tank in order to make the natural fluid circulation efficient.

[Operation] In order to circulate the fluid used for supercritical extraction between the extraction container and the separation container, the supercritical fluid extraction device of the present invention comprises:
By utilizing the temperature dependence of the specific gravity of the fluid in the supercritical region and its vicinity, the fluid at higher temperature and lighter specific gravity rises,
Fluids with a high specific gravity are smoothly and economically processed by natural fluid circulation that descends. The simplest device configuration for that purpose is to provide an efficient and expensive method by providing an extraction container and a separation container in the same tank in order to make the natural fluid circulation efficient, and causing natural convection in the same container. Got

One of the supercritical fluid extraction apparatus of the present invention is an operation apparatus in which a supercritical fluid efficiently circulates a supercritical fluid with respect to an object to be extracted, and extraction and separation are energy consuming such as a pump. It is intended to secure a fluid extraction device in the vicinity of a supercritical state that can perform a supercritical fluid extraction operation economically and energy saving without using it. It ensures efficient extraction operation of supercritical fluid and enhances its economic efficiency.

A general discussion of supercritical fluid extraction is as follows.

In supercritical fluid extraction, the capacity of supercritical gas as a solvent depends largely on its density. That is, the density of the gas in the supercritical state is considerably higher than that in the ordinary gas state, and is almost equal to the density in the liquid state near the critical temperature. Such an increase in density increases the chemical affinity with the solute and allows the supercritical gas to function as a separation medium. Therefore, under constant temperature conditions, the density of the supercritical gas increases as the pressure increases, and the solvent capacity increases accordingly. In fluid extraction near supercritical, the solubility increases as the temperature rises when the pressure is very high. This is because the density of the supercritical gas decreases as the temperature rises. This is because the vapor pressure of the substance to be extracted rises more markedly, and the dissolution in supercritical gas due to the vapor pressure rise contributes significantly. On the other hand, when the pressure is not so high, the solubility decreases as the temperature rises. This is because, in this case, the vapor pressure of the substance to be extracted is slightly increased, but the density of the supercritical gas is significantly reduced.
Thus, the solvent capacity of supercritical fluids is remarkable. On the other hand, the supercritical fluid in which the substance to be extracted is taken in as a solute can be easily separated and recovered.

According to the present invention, as shown in FIG. 1, a partition plate 5 that divides the space inside the container into two is provided in one container that also serves as an extraction tank and a separation tank, and the substance 2 to be extracted can be filled inside the partition plate 5. To do. On the other hand, a separating portion 7 is provided on the outer side thereof, and a filler or a filling material is filled therein, and the separated solute is retained by adhesion or adsorption. That is, the heating means 4 is installed in the extraction target material filling tank and heated by steam or electric heat. On the other hand, a cooler is installed in the outer separation region to cool the supercritical fluid and separate the solute.

As described in the above description, when the pressure is constant, depending on the pressure condition, the solubility may decrease with the temperature increase and the solubility may increase oppositely. Therefore, when the solubility decreases due to the temperature rise, the heating and cooling described above are reversed to enable efficient supercritical extraction and recovery separation.

Fluid extraction operation in the vicinity of supercritical state, for example, when carbon dioxide (CO ₂ ) is used for supercritical extraction, as shown in Fig. 3, the specific gravity (density) changes greatly near the critical point. Therefore, the device of the present invention can be operated very efficiently.
The vertical axis is the pressure P _r , and the horizontal axis is the specific gravity ρ _r . T _r is the T / T _c value,
That is, it is a value proportional to the critical temperature due to the absolute temperature. The shaded rhombus indicates the supercritical region.

From the industrial point of view, that is, in order to improve the economic efficiency of the extraction technique, supercritical fluid extraction is receiving more and more attention. From this point as well, the energy saving property of the supercritical fluid extraction technology is desired.

Since the supercritical fluid extraction is operated at a relatively low temperature, it is also used for treating thermally unstable substances, and is also used in the food and luxury goods industries. The device can be used. That is, it can be used for extraction of caffeine from coffee beans and tea, extraction of hops and spice extracts, or removal of nicotine from tobacco leaves. Further, the apparatus of the present invention can be used for a treatment for removing the binder material from the molded body before firing by forming the molded body by molding with the heat resistant material powder or the like.

[Embodiment] Next, one embodiment of the present invention will be described more specifically with respect to the supercritical fluid extraction apparatus of FIG. 1, but the present invention is limited to the following embodiment unless the gist thereof is changed. It is not something that will be done.

In the configuration of the present invention, one of the supercritical fluid extraction devices is
Is a supply pump, 2 is a substance to be extracted, for example, 3
Is a part where extraction is performed, and a spiral pipe 4 is arranged in the region for heating, and steam or a heating wire is passed therethrough. The extraction area portion 3 is filled with the extracted extract 2 to be extracted. The supercritical fluid rises because it is heated and lightened between the filled extracts, and at the same time, solutes such as caffeine and a binder agent are extracted from the extracts.

Reference numeral 5 denotes a cylindrical partition plate, which is a natural convection supercritical fluid convection-extracting portion 3 and a descending-flow extractor separating portion 7.
It is for separating. A spiral pipe 6 is arranged in the separation area 7 for cooling the fluid, and cooling water is passed through the spiral pipe 6. That is, the fluid for supercritical extraction flows as shown by arrows 11 and 12, and natural convection occurs according to the density (specific gravity) change of the fluid. In the extraction part 4 that is heated and in the supercritical state, the fluid that has been heated and has a high extraction capacity becomes less dense as the temperature rises and rises as shown in the figure. The fluid that has risen and reached the top of the container exits to the outside as shown, and the fluid cooled in the outer separation region 7 increases in specific gravity (density) and becomes heavier. Downflow occurs.

The cooled fluid leaves the state in the vicinity of the supercritical state and loses its dissolving ability. In the separation area portion 7, the solute (extracted substance) extracted in the fluid is taken out from the fluid and separated.
The separation area portion 7 is filled with an adsorbent and / or a packing material. This is to attach and capture the extract deposited from the fluid that has lost its dissolving ability and has exited the supercritical state. In particular, the adsorbent can also adsorb and capture the remaining dissolved material in the supercritical fluid.

The adsorbent must be selected according to the target extract, but typical examples include activated carbon and zeolite. Also, the packing is a material to which the precipitated extract is physically attached, and it is preferable that the packing has a large effective area and little pressure damage. As typical examples, Raschig rings, wire mesh, terraret punking, ball rings, honeycomb-shaped ones, or Melapack manufactured by Sumitomo Heavy Industries, Ltd. can be used.

The fluid that is heated and becomes a solvent in a supercritical state is pressurized to a predetermined pressure, flows between the substances to be extracted 2 in the extraction part 3, and while passing, dissolves the solute from the substances to be extracted. . Examples of the gas or fluid suitable for use as such a fluid include carbon dioxide gas, Freon (Freon {trademark}) gas, and the like.

It is supplied from the supply pump 1 to replenish the fluid. Since the fluid flow is circulated without using any mechanical force, a very economical supercritical extraction operation can be performed.

In Fig. 1, the extraction and separation tanks are provided in a single container,
Next, in FIG. 2, as shown in the drawing, an independent extraction tank (container) and separation tank (container) are provided and connected by a communication pipe,
The extraction tank is heated, the separation tank is cooled, and natural convection can circulate the fluid in the vicinity of the supercritical state. That is, when the substance to be extracted 2 is filled in the extraction tank 3 and the heating medium pipe 4 is piped therein, and a heating medium such as water vapor is flowed and heated, the fluid for supercritical extraction is heated. While being in a supercritical state, it rises in the extraction tank 3 to extract a solute such as a binder agent from the filled substance to be extracted.
The fluid that has risen and reached the upper portion of the extraction tank 3 is discharged from the extraction tank 3 as indicated by arrow 11, and enters the separation tank 7 through the cooling heat exchanger 15. A cooling medium introduction pipe 6 is arranged in the separation tank 7. Similar to Fig. 1, separation tank 7
The inside is filled with an adsorbent and / or a filling material. While the fluid cooled by the cooling pipe 6 descends in the separation tank, the extracted solute is separated and dropped as in the case of FIG. 1, that is, the solute is attached to and trapped in the adsorbent or the packing material. It The fluid that is not in the supercritical state descends to the lower part of the separation tank 7, and then enters the extraction tank 3 through the pipe provided with the heating heat exchanger 16 as shown by the arrow 12. That is, it is put into a supercritical state by the heating heat exchanger 16 and is recycled again to the extraction process.

[Effect of the Invention] The supercritical extraction apparatus of the present invention utilizes natural convection circulation due to the difference in density of the fluid as the extraction solvent, and can omit an expensive high-pressure pump or compressor for circulation between extraction and separation. Therefore, firstly, the simplification of the device and energy saving can be achieved remarkably, and secondly, the device can be made compact because it can be done in a single tank without using a pump or the like. Since the extraction and separation can be performed in one tank, technical effects such as supercritical extraction can be performed with a simple operation. Further, as described above, the supercritical fluid extraction device according to the method of the present invention can significantly reduce the operating cost as compared with the conventional device, and is very effective in energy saving.

[Brief description of drawings]

FIG. 1 is an explanatory view of a schematic cross section showing one embodiment of the supercritical fluid extraction device of the present invention. FIG. 2 is an explanatory view having a schematic sectional view showing another embodiment of the supercritical fluid extraction device of the present invention. FIG. 3 shows the specific gravity (density) ρ _r and pressure P _r near the critical point of carbon dioxide (CO ₂ ) for supercritical extraction used in the present invention.
3 is a graph showing the relationship between temperature and temperature. [Explanation of symbols of main parts] 1 ... Supply pump; 2 ... Extracted material; 3 ... Extraction area part (tank) 4 ... Helical pipe (for steam or electric heating); Heating medium pipe; 5 ... ... Cylindrical partition plate; 6 ... spiral pipe (for cooling water); cooling medium pipe; 7 ... (extract) separation area part (tank) 11 ... extraction fluid flow; 12 ... extract Flow of fluid that has been separated into: 14 ... Cooling heat exchanger; 16 ... Heating heat exchanger;

Claims (2)

[Claims] 1. In a supercritical fluid extraction device, by utilizing the temperature dependence of the specific gravity of the fluid in the vicinity of the supercritical point, a fluid having a low specific gravity rises and a fluid having a high specific gravity descends due to natural fluid circulation. An apparatus for extracting a supercritical fluid, characterized in that an extraction fluid is circulated between an extraction region part for performing an extraction process and a separation region part for performing a separation process. 2. The supercritical fluid extraction apparatus according to claim 1, wherein the extraction area portion and the separation area portion are provided in the same tank in order to make the natural fluid circulation efficient. Characteristic supercritical fluid extraction device.