JP2005007293A - Apparatus for manufacturing fine particle supercritically - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new apparatus for manufacturing a fine particle supercritically in which the clogging of a nozzle can be avoided and the operating rate of which can be improved by improving the efficiency when a supercritical fluid with a solute from the nozzle dissolved therein is sprayed through the nozzle. <P>SOLUTION: This apparatus is constituted in such a manner that a granular substance G is obtained by spraying the solute-dissolved supercritical fluid F from the nozzle 20 arranged in a collector 2 and rapidly expanding the sprayed fluid F to precipitate the solute and the fluid F is supplied to a route between a reactor 1 and the collector 2 to keep the inside of a route from the reactor 1 to the nozzle 20 in a supercritical environment. The precipitation of the solute from the solute-dissolved supercritical fluid S flowing out in the route from the reactor 1 to the nozzle 20 can be avoided by filling the route between the reactor 1 and the collector 2 with the fluid F. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fine particle production technique using a supercritical fluid, and relates to a fine particle production apparatus capable of simple and efficient particle production.
[0002]
BACKGROUND OF THE INVENTION
The phase state of a substance is determined by the balance between the kinetic energy of the molecule and the intermolecular force. When the intermolecular force is dominant, the substance becomes a liquid with some order, while the kinetic energy is dominant. In some cases, the material becomes a disordered gas. In other words, a substance becomes a three-phase gas, liquid, or solid due to changes in temperature and pressure. As shown in the phase diagram of FIG. The boundary surface disappears and becomes a supercritical fluid in which liquid and gas cannot be distinguished. The physical properties of this supercritical fluid are such that the density is close to that of a liquid, the viscosity and diffusion coefficient are close to those of a gas, and even a non-volatile substance that is solid at room temperature can be dissolved and can move faster than a liquid. It is.
[0003]
In recent years, attention has been paid to the physical properties of such supercritical fluids, and various studies have been conducted on using them as new solvents instead of liquid solvents. Specifically, in the production of powders of foods, pharmaceuticals, agricultural chemicals, chemicals, etc., research on particle production using supercritical technology has been conducted, and one of them is the RESS method (Rapid Expansion of Supercritical Solutions). There is a method called. In this method, the supercritical fluid in which the solute is dissolved is rapidly expanded under reduced pressure to create a supersaturated dissolution state of the solute (raw material) to precipitate the solute. Is something that can be done.
[0004]
As an apparatus for carrying out the RESS method, there is a supercritical fine particle production apparatus D ′ as shown in FIG. This apparatus obtains a supercritical solution S in which a solute is dissolved in a reactor 1 ', and sprays this from a nozzle 20' provided in a collector 2 ', thereby making the solute M into fine particles. It is an apparatus which obtains the granular material G by making it precipitate.
[0005]
However, the supercritical fine particle production apparatus D ′ has several problems due to its structure.
First, as a first problem, the spray of the supercritical fluid S in which the solute from the nozzle 20 'is dissolved is a valve V4 provided in the main pipe line 7' connecting the reactor 1 'and the collector 2'. ′ Is opened, but the section between the valve V4 ′ and the nozzle 20 ′ is in an atmospheric pressure state before the valve V4 ′ is opened, so the valve V4 ′ is opened. In the supercritical fluid S in which the solute flowing into this section is dissolved, the solute is precipitated, and the nozzle 20 'may be clogged.
[0006]
As a second problem, in this type of apparatus, the smaller the diameter of the orifice hole 21 ′ in the nozzle 20 ′, the smaller the fine particles are obtained. Since the spray amount per hour decreases, it takes a long time to spray all the supercritical fluid S in which the solute in the reaction vessel 1 'is dissolved.
Further, in the nozzle 20 'having a small diameter orifice hole 21', there is a high probability that the solute deposited in the section between the valve V4 'and the nozzle 20' is clogged.
[0007]
As a third problem, since the inside of the system drops to atmospheric pressure after the supercritical particle production apparatus D 'is stopped, the solute remaining in the reactor 1', the collector 2 'and the main pipe line 7' is dissolved. It was inevitable that the solute was precipitated from the supercritical fluid S that was allowed to enter.
For this reason, conventionally, methanol or ethanol is injected into the piping to remove the precipitated solute. When the supercritical fine particle production apparatus D ′ is restarted in a state where methanol or ethanol used for washing remains undried, the supercritical fluid S in which the solute is dissolved by methanol or ethanol is used. Since the temperature is lowered and solute is precipitated at that location, the inside of the pipe is purged with fine carbon oxide and dried at room temperature or heat after washing.
However, such a cleaning method has a problem that the degree of cleaning in the pipe is unknown, and in the case of disassembly cleaning of the pipe line, it takes time to reassemble.
[0008]
[Technical problem to be solved]
The present invention has been made in view of such a background, it is possible to avoid clogging of the nozzle, and by improving the spray efficiency of the supercritical fluid in which the solute from the nozzle is dissolved, The technical challenge is to develop a new supercritical fine particle production system that can improve the operating rate.
[0009]
[Means for Solving the Problems]
That is, the supercritical fine particle manufacturing apparatus according to claim 1 is configured to pressurize and raise the temperature of the liquid by a pump and a preheater to obtain a supercritical fluid, and dissolve the solute in the supercritical fluid in the reactor. A device for obtaining a granular material by precipitating a solute by rapidly spraying the supercritical fluid in which the solute is dissolved and spraying it from a nozzle provided in the collector. The supercritical fluid is supplied to the path between the reactor and the collector so that the path from the reactor to the nozzle can be in a supercritical environment. Is a feature.
According to the present invention, the supercritical fluid in which the solute flowing out from the reactor into the pipe line is dissolved in this section by filling the pipe line connecting the reactor and the collector with the supercritical fluid. It is possible to avoid the solute from being precipitated.
[0010]
In addition, the supercritical fine particle production apparatus according to claim 2 is a method in which the liquid is pressurized and heated by a pump and a preheater to form a supercritical fluid, and the solute is dissolved in the supercritical fluid in the reactor. A device for obtaining a granular material by precipitating a solute by rapidly spraying the supercritical fluid in which the solute is dissolved and spraying it from a nozzle provided in the collector. The nozzle is characterized in that a plurality of orifice holes are formed.
According to this invention, since the spray amount of the supercritical fluid in which the solute from the nozzle per unit time is dissolved increases, the operation efficiency can be improved.
[0011]
Furthermore, the supercritical particle production apparatus according to claim 3 is characterized in that, in addition to the above requirements, a filter having a finer diameter than the diameter of the orifice hole is provided between the reactor and the nozzle. is there.
According to this invention, since the undissolved raw material (solute) flowing out from the reactor and the solute deposited in the front stage of the collector are captured by the filter, clogging of the orifice hole can be avoided.
[0012]
Furthermore, in addition to the above requirements, the supercritical fine particle production apparatus according to claim 4 is characterized in that a pipe line for supplying a cleaning solvent is connected to a pre-stage portion of the preheater in the pipe line. It is.
According to this invention, together with the supercritical fluid, the solvent is allowed to pass through the system at high pressure (supercritical pressure) and medium temperature (supercritical temperature), so that the solute remaining in the system is reliably removed and dried. Can do. Further, since the pipes need not be disassembled and reassembled, the cleaning operation can be performed efficiently.
The above problems can be solved by using the configuration of the invention described in each of the claims as a means.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The supercritical fine particle production apparatus D of the present invention will be described below. This apparatus is a collector of a supercritical fluid S in which a solute obtained by dissolving a solute M in a supercritical fluid F in a reactor 1 is dissolved. 2 is a device that obtains a granular material G having a desired property by spraying from a nozzle 20 provided in 2 and rapidly expanding. Further, such a supercritical fine particle production apparatus D is provided with a system for obtaining the supercritical fluid F. As an example, the carbon dioxide filled in the cylinder 3 is cooled in the chiller unit 4, Subsequently, the pump 5 and the preheater 6 are used to increase the pressure and raise the temperature so that the critical point is exceeded. Carbon dioxide is available at a relatively low price, and has a critical pressure of 31.1 ° C. and a critical pressure of 7.38 MPa, and is a solvent that can be easily separated because it becomes a gas at normal temperature and normal pressure. .
[0014]
Hereinafter, various members constituting the supercritical fine particle production apparatus D will be described in detail.
First, the reactor 1 is a container used to dissolve the solute M in the supercritical fluid F as a solvent, and is configured to be hermetically sealed using SUS316 or SUS316L as a material. In this embodiment, since a supercritical fluid F of carbon dioxide is used as a solvent, it is designed to withstand a maximum pressure of 20.0 MPaG and a maximum temperature of 150 ° C. as an example.
Further, the reactor 1 is provided with a stirrer 10 for stirring and mixing the solute and the solvent.
[0015]
Next, the collector 2 will be described. The collector 2 comprises a nozzle 20 for ejecting a supercritical fluid S in which a solute is dissolved in a casing formed so as to maintain an airtight state. is there. A plurality of orifice holes 21 are formed in the nozzle 20, and the one shown in FIG. 2A is formed so that three orifice holes 21 are directed in the same direction. FIG. 2B shows a structure in which a group of three orifice holes 21 oriented in the same direction is oriented in two directions, and a single orifice hole 21 oriented in a different direction is formed. It is. Furthermore, what is shown in FIG. 2 (c) is formed by changing all the directions in which the three orifice holes 21 are directed. Of course, the number of orifice holes 21 and the locations where they are formed can be appropriately changed according to the solute and solvent to be handled.
[0016]
The nozzle 20 is connected to a main pipe line 7 connected to a nozzle insertion port 22 formed in the top plate portion of the casing as an example, and a filter 23 is provided between the reactor 1 and the nozzle 20. Is provided. Since this filter 23 is installed for the purpose of preventing the orifice hole 21 from being clogged, it is preferably provided immediately before the nozzle 20, and a mesh smaller than the diameter of the orifice hole 21 is used. It is provided as a filter body.
On the other hand, the exhaust port 24 formed in the top plate portion is also provided with a filter 25, and this filter 25 is installed for the purpose of preventing the powder G from flowing out from the collector 2. Therefore, a mesh smaller than the diameter of the granular material G is provided as a filter body.
[0017]
Next, the cylinder 3 will be described. This is a member for holding the liquefied gas, and is provided with a valve V1 at the mouth. In this embodiment, liquefied carbon dioxide is filled.
[0018]
Next, the chiller unit 4 will be described. The chiller unit 4 includes an appropriate cooling means and a cooling surface. By cooling the liquid touching the cooling surface, bubbles are generated at the inlet of the pump 5. It is a device to prevent.
[0019]
Next, the pump 5 will be described. This is a member for increasing the pressure of the liquid, and is provided with an inverter for appropriately controlling the rotation speed.
[0020]
Next, the preheater 6 will be described. This is a member for raising the temperature of the liquid cooled in the chiller unit 4, and comprises an appropriate heating means.
[0021]
The above members are connected by a main line 7 made of SUS316 or SUS316L as a material in the order of the cylinder 3, the chiller unit 4, the pump 5, the preheater 6, the reactor 1, and the collector 2.
That is, carbon dioxide, which is a liquid in the cylinder 3, is introduced into the main pipeline 7, supplied to the reactor 1 in a state of being a supercritical fluid F by the action of the pump 5 and the preheater 6, and further in the reactor 1. The supercritical fluid S in which the solute M has been dissolved is sprayed into the collector 2 in a state where the solute M is dissolved. .
The main pipeline 7 in the section connecting the reactor 1, the collector 2 and the two devices is disposed in the thermostatic bath 8, and is configured to be able to maintain a desired temperature. Further, instead of such a constant temperature bath 8, an appropriate heater may be wound around the main pipeline 7 in the section connecting the reactor 1, the collector 2 and the two devices.
[0022]
Valves V2, V3, V4, and V5 are provided between the devices in the main pipeline 7, and the main pipeline 7 is opened and closed by the individual valves V.
Further, a filter 70 is provided immediately after the valve V4 provided between the reactor 1 and the collector 2, and this filter 70 cannot be completely dissolved in the supercritical fluid F in the reactor 1. Are disposed for the purpose of removing the solute M flowing out of the reactor 1 in the form of a solid.
[0023]
Further, a return line 71 having a relief valve 71 a is provided between a part immediately after the pump 5 in the main line 7 and a part immediately before the chiller unit 4. The pressure is increased through the return line 71. It is comprised so that the pressure of a granule can be adjusted by feeding back gas.
[0024]
Furthermore, a sub-pipe 72 having a valve 72a is provided between a portion immediately after the preheater 6 in the main pipe 7 and a portion immediately before the collector 2, and this sub-pipe 72 is In order to satisfy the supercritical fluid F supplied from the preheater 6 in the range from the valve V4 to the valve V5.
Note that the secondary pipe 72 can also be arranged in the thermostatic chamber 8 in the same manner as the reactor 1, the collector 2 and the main pipe 7 connecting these devices.
[0025]
Furthermore, a cleaning line 73 having a valve 73a is connected to the pre-stage portion of the preheater 6 in the main line 7, and a solvent such as ethanol is appropriately stored in the cleaning line 73. The tank is connected. Furthermore, a pressure sensor P or a temperature sensor T is appropriately provided in the main pipe line 7 and each device.
[0026]
The supercritical fine particle production apparatus D of the present invention is configured as described above as an example, and the production process of the powder G by the RESS method will be described below together with the operation mode of this apparatus. In this embodiment, naphthalene is used as the solute M, carbon dioxide supercritical fluid F is used as a solvent, and a process of finally obtaining a granular material G having a particle size of about 0.01 mmφ will be described.
[0027]
(1) Feeding Raw Material First, naphthalene as the solute M is fed into the reactor 1 with all the valves V closed, and methanol is further fed as a co-solvent H as required. The cosolvent H increases the solubility of the solute M only when mixed with the supercritical fluid F, and an appropriate one is selected according to the solute M.
[0028]
(2) Generation of supercritical fluid Next, valves V1, V2, and V3 are opened. Carbon dioxide that is liquid in the cylinder 3 is introduced into the main pipe 7 as a gas. Cooling prevents foaming. The carbon dioxide is increased in pressure and heated by the action of the pump 5 and the preheater 6 to exceed the critical point, and is supplied to the reactor 1 in a state of becoming a supercritical fluid F. In this embodiment, the pressure of the supercritical fluid F is increased to 15 MPaG, and the temperature is increased to 60 ° C.
The gas pressure is adjusted by monitoring the pressure of the gas with a pressure sensor P1 provided at the rear stage of the pump 5 and adjusting the opening of the relief valve 71a as appropriate, so that a part of the boosted gas is moved upstream of the chiller unit 4. This is performed by feeding back to the part and controlling the rotational speed of the pump 5 by an inverter.
[0029]
(3) Generation of a supercritical fluid in which a solute is dissolved and the supercritical fluid F is sequentially supplied to the reactor 1, and the pressure sensor P2 indicates that the pressure in the reactor 1 has reached a predetermined value. The valve V3 is closed at the time point detected by. At this time, the reactor 1 is kept at a constant temperature (60 ° C.) because it is in the thermostat 8, and the solute M (naphthalene) is dissolved in the supercritical fluid F to dissolve the solute. A fluid S is generated. At this time, the stirrer 10 is appropriately activated to promote dissolution.
[0030]
(4) Valve 72a is opened while filling of the supercritical fluid into the main pipe line and dissolution of the solute M is in progress or when dissolution of the solute M is completed, and a section from the valve V4 to the nozzle 20 Is filled with the supercritical fluid F.
[0031]
(5) Generation of granular material Next, the valve V4 is opened and the valve 72a is closed simultaneously. At this time, since the section from the valve V4 to the nozzle 20 is filled with the supercritical fluid F, the solute is dissolved. The supercritical fluid S thus caused does not expand rapidly, and precipitation of naphthalene as a solute does not occur.
At this time, since the inside of the collector 2 is depressurized to atmospheric pressure, the supercritical fluid S in which the solute in the main pipe line 7 connecting the reactor 1 and the collector 2 is dissolved is the nozzle 20. And then rapidly expands in the collector 2 to precipitate naphthalene, which is a solute, and eventually the desired granular material G is obtained.
At this time, if there is undissolved naphthalene in the reactor 1, this is captured by the filter 70, and the finer one is captured by the filter 23, so that the orifice hole 21 of the nozzle 20 is clogged. Can be avoided.
On the other hand, the carbon dioxide that has become gas with the precipitation of the solute is exhausted to the outside together with the vaporized cosolvent H.
According to the present invention, since a plurality of orifice holes 21 are formed in the nozzle 20, the spray amount per unit time is large, and the supercritical fluid S in which the solute in the reactor 1 is dissolved is dissolved. Spraying, that is, production of the powder G can be performed in a short time.
[0032]
(6) Maintenance A supercritical fluid in which a solute is dissolved in the reactor 1, the collector 2 and the main pipeline 7, the valve V4, the filter 23, etc., when the production of such a series of particles G is completed. It is inevitable that S will adhere and remain. In the supercritical fluid S in which the solute remaining in the system is dissolved in this way, the inside of the system is reduced to atmospheric pressure, so that naphthalene as a solute is precipitated and the reactor 1, the collector 2 and the main pipe line 7 are deposited. In addition, it adheres to the valve V4, the filter 23, the nozzle 20 and the like as foreign matter.
Therefore, the supercritical fluid F and the cleaning solvent are sent to the location where the solute adheres. First, the valve V2 and the valve 73a are appropriately closed with the valve 72a closed and the valves V3 and V4 opened. The preheater 6 is supplied with a mixture of the solvent and the cleaning solvent whose pressure is increased by adjusting the opening degree. In this embodiment, carbon dioxide is used as the supercritical fluid F and ethanol is used as the cleaning solvent. The carbon dioxide is heated by the preheater 6 to become the supercritical fluid F, while ethanol is also the supercritical fluid F. The same high pressure and medium temperature as those described above are used to dissolve and remove the remaining solutes when they pass through the reactor 1, the filter 70, the filter 23, the nozzle 20, and the main pipeline 7. Subsequently, the valve V3 and the valve V4 are closed and the valve 72a is opened to clean the inside of the auxiliary pipe line 72. Note that the reactor 1 can be exchanged during cleaning of the sub-pipe 72.
[0033]
[Other embodiments]
Although the present invention is based on the above-described embodiment, it is also possible to adopt the following embodiment based on the technical idea of the present invention.
First, in the basic embodiment described above, the supercritical fluid F of carbon dioxide is used as the solvent, but in addition to this, a supercritical fluid F such as methanol or water can be used as the solvent.
[0034]
Further, in the basic embodiment described above, the secondary pipe 72 is provided between the part immediately after the preheater 6 and the part immediately before the collector 2, and the main pipeline between the preheater 6 and the reactor 1 is provided. 7, the supercritical fluid F is supplied into the path from the reactor 1 to the nozzle 20, but the cylinder 3, the chiller unit 4, the pump 5, and the preheater provided separately. 6, the supercritical fluid F can be supplied into the path from the reactor 1 to the nozzle 20.
[0035]
Furthermore, in the basic embodiment described above, the cleaning pipe 73 provided with the valve 73a is connected to the front part of the preheater 6 in the main pipe 7, but the cleaning pipe 73 is connected to the rear stage of the preheater 6. You may make it connect to a part. In this case, the carbon dioxide that has become the supercritical fluid F and the cleaning solvent are mixed in the main pipeline 7.
[0036]
【The invention's effect】
According to the present invention, clogging of the nozzle 20 can be avoided, and the operating efficiency of the supercritical fine particle production apparatus D is improved by improving the spray efficiency of the supercritical fluid S in which the solute from the nozzle 20 is dissolved. And the production efficiency of the granular material G can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an apparatus for producing supercritical fine particles of the present invention.
FIG. 2 is a vertical side view showing a nozzle.
FIG. 3 is a graph showing the state of carbon dioxide when the pressure and temperature are changed.
FIG. 4 is a block diagram showing an existing supercritical fine particle production apparatus.
[Explanation of symbols]
D Supercritical particle production apparatus 1 Reactor 10 Stirrer 2 Collector 20 Nozzle 21 Orifice hole 22 Nozzle insertion port 23 Filter 24 Exhaust port 25 Filter 3 Cylinder 4 Chiller unit 5 Pump 6 Preheater 7 Main line 70 Filter 71 Return pipe Path 71a Relief valve 72 Sub pipe 72a Valve 73 Cleaning pipe 73a Valve 8 Thermostatic bath F Supercritical fluid G Granule H Cosolvent M Solute P Pressure sensor P1 Pressure sensor P2 Pressure sensor S Supercritical with dissolved solute Fluid T Temperature sensor V Valve

Claims (4)

The pressure of the liquid is increased by a pump and a preheater and the temperature is raised to a supercritical fluid. In the reactor, the solute is dissolved in the supercritical fluid to obtain a supercritical fluid in which the solute is dissolved. In a device for precipitating a solute by spraying the dissolved supercritical fluid from a nozzle provided in the collector and rapidly expanding, in the apparatus from the reactor to the nozzle, An apparatus for producing supercritical fine particles, characterized in that the supercritical fluid is supplied to a path between the reactor and the collector so as to be in a critical environment. The pressure of the liquid is increased by a pump and a preheater and the temperature is raised to a supercritical fluid. In the reactor, the solute is dissolved in the supercritical fluid to obtain a supercritical fluid in which the solute is dissolved. In the apparatus for precipitating the solute by spraying the dissolved supercritical fluid from the nozzle provided in the collector and rapidly expanding, the nozzle has a plurality of orifice holes. An apparatus for producing supercritical fine particles, characterized in that The supercritical fine particle production apparatus according to claim 1 or 2, wherein a filter having a finer diameter than the diameter of the orifice hole is provided between the reactor and the nozzle. The supercritical fine particle manufacturing apparatus according to claim 1, 2 or 3, wherein a pipe line for supplying a cleaning solvent is connected to a pre-stage portion of the preheater in the pipe line.

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