JPS6146202A - Drying method of difficult-to-dry substance or heat-sensitive substance - Google Patents

Abstract

PURPOSE:To dry uniformly and completely the titled substance without causing any thermal deformation in a short time at low temps. by using CO2 in a liquid or a super critical state, and extracting a solvent contained in a difficult-to- dry substance or a heat-sensitive substance. CONSTITUTION:A material such as a difficult-to-dry or a heat-sensitive substance is packed into a drying tower 1, and CO2 in a liquid or a super critical state, which is regulated to 30-200kg/cm<2> G, preferably about 40-100kg/cm<2> G, and at -10-100 deg.C, preferably about 0-50 deg.C, by a booster 5 and a heat exchanger 6, is supplied to extract a solvent contained in said material. A CO2 phase contg. the solvent discharged from the drying tower 1 is vaporized in a heater 2 or decompressed by a reducing valve 3 to deposit the solvent which is recovered in a solvent recovery tower 4. The solvent is further recovered, if necessary, in an absorption vessel or a washing vessel 8, and the separated CO2 is again supplied into the drying tower 1 through the booster 5 and the heat exchanger 6.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to converting a solvent such as water or an organic solvent contained in a difficult-to-dry substance or a heat-sensitive substance (hereinafter sometimes simply referred to as a “substance”) into a liquid. The present invention relates to a method of extracting the substance using carbon dioxide in a state or a supercritical state and drying the substance.

Conventional technology) Conventional methods for drying slurry, glue substances such as gelatin and cheese, or substances that are difficult to dry such as antibiotics: i) To obtain a dry product from a fine particle suspension, solution or slurry at once. ii) Spray drying method, in which droplets are atomized and dispersed in hot air, and the hot air and material are brought into contact with a parallel flow, countercurrent flow, or a combined flow of parallel countercurrent flow, and then dried; ii) using a drum dryer or the like in a vacuum. iii) freezing the material containing a relatively large amount of water;
Freeze-drying method, in which this is sublimated and dried at a temperature below the freezing point in a vacuum with an operating pressure of about 17'orr, to obtain a porous product, iv) Natural drying method, in which it is dried in natural conditions for a long time, etc. In particular, the latter three methods (ii = iv) are adopted for difficult-to-dry substances or heat-sensitive substances that are difficult to dry, such as foods and medicines, and that are easily denatured by heat.

(Problems to be Solved by the Invention) However, even if the above-mentioned drying method is applied to these difficult-to-dry substances or heat-sensitive substances, There is a problem in that a glass-like film is formed when drying only, and the drying process stops midway through.To prevent this, humidity must be adjusted and drying must be carried out for a long time under gentle conditions. ■Due to the long drying time required, deterioration of the product during that time is unavoidable; ■As mentioned above (partial drying phenomenon is likely to occur, the product is likely to become heterogeneous (and complete drying is likely to occur); It has the disadvantages that it is difficult to dry and the solvent tends to remain inside the product.

The present invention was made against the background of conventional technical problems, and its purpose is to shorten the drying time when drying difficult-to-dry substances or heat-sensitive substances, and to dry them at low temperatures without causing heat denaturation. Furthermore, it is an object of the present invention to provide a drying method that enables uniform and complete drying.

Means for Solving the Problems) That is, the present invention can be applied to difficult-to-dry substances, heat-sensitive substances, liquids, Li, and supercritical substances. This is a method for drying a difficult-to-dry substance or a heat-sensitive substance, which is characterized in that the substance is dried by extracting the solvent contained in the substance using sulfuric acid and charcoal.

Liquid state or supercritical state 1! Carbon dioxide (hereinafter sometimes simply referred to as "carbon dioxide") (temperature 31°C or higher, pressure cuff 2.8kg/aaG or higher), especially carbon dioxide in a supercritical state, requires water, methanol, ethanol, or ethyl acetate. , butyl acetate, acetone, isopropyl alcohol, and other organic solvents (hereinafter sometimes simply referred to as "solvents"), and the present invention utilizes the properties of such carbon dioxide as an extraction solvent and its high vapor pressure. This was developed with a focus on high mass transfer rate and non-toxicity.

Here, the pressure of carbon dioxide is 30 to 200 kg/-G, preferably 40 to 100 kg/aJG, and the temperature is -10 to 200 kg/aJG.
The temperature is 100°C, preferably 0 to 50°C. Particularly in the case of a supercritical state, it is easier to extract the solvent if the temperature is as close to the critical temperature as possible, while the pressure is as high as possible above the critical pressure.

After extracting the solvent contained in a substance with carbon dioxide, in order to recover the solvent from the carbon dioxide phase, the solvent can be easily removed by, for example, reducing the pressure of the carbon dioxide phase to a gas below the critical pressure. Can be separated.

The carbon dioxide thus extracts the solvent contained in the material and the material is dried.

In one embodiment of the present invention, carbon dioxide contains a solvent B that dissolves in the solvent A contained in the substance and is easily extracted into carbon dioxide by the solvent A, first replaces and extracts the solvent A, and then The material may be dried by extracting the solvent B using only carbon dioxide; in another embodiment, the material is soluble in the solvent A contained in the material and is easily extracted by the carbon dioxide. Solvent B may be first added to the material to displace dissolved A, and then only carbon dioxide may be used to extract solvent B and dry the material.

The present invention will be explained in more detail below using the drawings.

FIG. 1 is a flowchart of the extraction/drying apparatus used in the present invention, and FIG. 2 is a model drying curve diagram showing the relationship between drying time and solvent residual rate.

First, referring to Figure 1, the raw material (substance) is in the drying tower 1.
is filled with. Although the drying tower 1 is shown as a packed tower, it may be in other formats such as a moving bed or a fluidized bed. Carbon dioxide is heated to a pressure of 30 to 200 pupils/cjG by a booster 5,
Preferably, the pressure is increased to 40 to 100 kg/aJG, and the temperature is -10 to 100°C, preferably 0
The temperature is adjusted to ~50°C and supplied to the dryer 1.

The pressure and temperature of carbon dioxide at this time are appropriately selected in consideration of the raw materials and the type of solvent to be dried and removed, and the operating efficiency.

In the drying tower 1, the solvent contained in the raw material is extracted with carbon dioxide, and the carbon dioxide phase containing the solvent leaves the drying tower 1 and is vaporized in the heater 2 or reduced in pressure in the pressure reducing valve 3 to remove the solvent. is precipitated, and the solvent is recovered in the solvent recovery tower 4. For separation of carbon dioxide and solvent, an adsorption tank, a washing tank 8, or a combination thereof may be used instead of the solvent recovery column 4 or in combination with the column 4, if necessary.

The separated carbon dioxide is again supplied to the drying tower 1 via the booster 5 and the heat exchanger 6.

As described above, the gist of the present invention is to extract the solvent contained in a difficult-to-dry substance or a heat-sensitive substance using carbon dioxide. In cases where the drying of a substance and the residual rate of solvent are extremely strictly controlled, the following two embodiments are more effective in drying a substance containing a solvent that is present in the human body.

That is, in one embodiment, in FIG. 1, first, a solvent (solvent B) that is soluble in the solvent (solvent A) contained in the raw material and is more easily extracted and dried by carbon dioxide than solvent A is used. 5 to 5 for carbon dioxide by solvent addition pump 7
A mixture of carbon dioxide and solvent B is added to the dryer 1 in an amount of 0% by weight, preferably 5 to 30% by weight, and the same operation as described above is performed to replace and extract the solvent A. In this way, solvent A in the raw material is extracted and removed by carbon dioxide while being replaced by solvent B. After the solvent A is extracted and removed, the addition of the solvent B by the solvent addition pump 7 is stopped, and only carbon dioxide is then supplied to the drying tower 1, thereby extracting and removing the solvent B substituted and contained in the raw material. do it.

In this case, the solvent B is appropriately selected according to the model drying curve diagram shown in FIG.

In other words, Figure 2 shows the relationship between the solvent residual rate in the substance and the drying time when the solvent contained in the substance is extracted and dried using carbon dioxide as a drying medium, as a model drying curve. , for example, the same thing! The extraction rate (drying rate) of solvents using carbon dioxide (antibiotics) is in the following order: methyl ethyl ketone, ethanol, methanol, and water. Therefore, for example, if methanol is contained in the substance and it is desired to be dried and removed, ethanol or methyl ethyl ketone is selected as the solvent B.

Furthermore, if the substance contains water and it is desired to dry and remove it, methanol or ethanol is selected as the solvent B, excluding methyl ethyl ketone which is insoluble in water.

In another embodiment of the present invention, only the solvent B selected in the above embodiment is first supplied in advance to the drying tower 1 by the solvent addition pump 7 to replace the solvent A in the substance. According to the outline, solvent B may be extracted using only carbon dioxide.

Function) In conventional drying mechanisms, the drying and movement of the solvent contained in the substance to be removed is performed by evaporation accompanied by heat transfer, whereas the present invention uses carbon dioxide in a liquid or supercritical state to the substance. The solvent is extracted and removed by dissolving the solvent contained in the substance in carbon dioxide, and the substance is dried. Carbon dioxide may remain in the substance after extraction and drying, but since carbon dioxide has a high vapor pressure, it easily vaporizes and disappears from the substance.

Example) EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 Ovalbumin was precipitated by pHtli adjustment, washed with ethanol, and the resulting filter cake was subjected to a pressure of 60To
When normal vacuum drying is performed at a temperature of 15°C and using the apparatus shown in Figure 1, the pressure is 10Gkg/cgi.
FIG. 3 shows the results of drying using only carbon dioxide at a temperature of 15° C. as an extraction solvent.

As is clear from Fig. 3, according to normal vacuum drying, 2
Even after drying for 0 hours or more, the residual rate of the solvent is 10% by weight or more, and even after that, the residual rate remains unchanged.However, when carbon dioxide is extracted as the drying medium as in the present invention, If the drying time is 5 hours, the residual rate of solvent is 5% by weight.
It turns out that the following can be done.

Example 2 A pharmaceutical raw material (antibiotic) containing methanol or ethanol as a solvent was heated at a pressure of 60 Torr and a temperature of 10°C.
Figure 4 shows the results when ordinary vacuum drying was carried out at .

As is clear from Figure 4, normal vacuum drying requires a long period of time, from 10 days to 2 weeks, whereas in the present invention, in which carbon dioxide is extracted as the drying medium, the drying time is 4.
It can be seen that almost complete drying can be achieved within hours.

Example 3 In order to remove metal contained in pharmaceutical raw materials (antibiotics) by drying, we focused on the fact that ethanol is more easily extracted by carbon dioxide than methanol, as shown in Figure 2, and used Figure 1. 1 apparatus, and using ethanol as solvent B, 20% by weight of ethanol was added to carbon dioxide from solvent addition pump 7, and the pressure was 60%.
By supplying kg/dG1 at a temperature of 10°C for 5 hours,
Methanol contained in the raw material was removed by drying.

Table 1 also shows the results of extracting and removing the pharmaceutical raw materials containing methanol and alcohol for 5 hours using only carbon dioxide under the conditions described above.

Table 1 Effects of the Invention) As described above, according to the present invention, since the solvent contained in the substance is transferred to carbon dioxide by dissolution, high temperature is not required during drying, and carbon dioxide Due to the high mass transfer rate, the solvent moves quickly inside the material, which eliminates the problem of conventional technology, such as glass film formation due to drying of only the surface of the material, and non-uniformity of the product. Does not occur.

Furthermore, unlike the conventional drying mechanism that requires heat transfer, the present invention uses carbon dioxide to remove the solvent contained in the substance by displacement or extraction. Complete drying is possible, and complete drying can be accomplished in a shorter time by using solvent B in combination as described above.

As described above, in the present invention, difficult-to-dry substances or heat-sensitive substances can be dried in a short time, and since carbon dioxide is chemically inert, there is no deterioration of the product, and carbon dioxide has a high vapor pressure. It has the advantage that the carbon dioxide does not remain in the product even after the extraction process, and even if a small amount remains, it is harmless to the human body and does not cause any problems.

[Brief explanation of the drawing]

Figure 1 is a flowchart of the extraction/drying apparatus used in the present invention, Figure 2 is a model drying curve diagram showing the relationship between drying time and solvent residual rate, and Figures 3 and 4 are the relationship between drying time and solvent residual rate. It is a drying curve diagram showing the relationship. In Figure 1, 1 is a drying tower, 2 is a heater, 3 is a pressure reducing valve, 4 is a solvent recovery tower, 5 is a pressure booster, 6 is a heat exchanger, 7 is a solvent addition pump, 8 is an adsorption tower or a washing tower It is. Patent applicant Mitsubishi Kakoki Co., Ltd. Agent Patent attorney Shige Takashi Shirai No. 2 Figure 773 (Hr) No. 3 J'/I (Hr)

Claims (1)

[Claims] 1. A difficult-to-dry substance characterized by drying a difficult-to-dry substance or a heat-sensitive substance by extracting a solvent contained in the substance using liquid or supercritical carbon dioxide. Methods of drying substances or heat-sensitive substances. 2. Carbon dioxide has a pressure of 30 to 200 kg/cm^2G,
The method for drying a difficult-to-dry substance or a heat-sensitive substance according to claim 1, wherein the temperature is -10 to 100°C. 3. Dissolved in the solvent A contained in the substance and the solvent A
Claim 1 or 2, wherein the carbon dioxide contains a solvent B that is more easily extracted by the carbon dioxide, first replaces and extracts the solvent A, and then extracts the solvent B using only the carbon dioxide. Method for drying difficult-to-dry substances or heat-sensitive substances as described in . 4. Dissolved in the solvent A contained in the substance and the solvent A
The method according to claim 1 or 2, wherein solvent B, which is more easily extracted by carbon dioxide, is first added to the substance to replace solvent A, and then solvent B is extracted using only carbon dioxide. Methods for drying desiccant or heat-sensitive substances.