Spray drying device

Abstract

Provided is a spray drying device which has a low drying temperature and can shorten a drying time, at the same time, can avoid the attachment and depositing of solutes on the inner wall surface of the device, can avoid the denaturation, decomposition, deterioration, etc. of solute components, and can obtain fine and uniform particulate powder. The spray drying device comprises: an ultrasonic spray unit including a mist discharge means for discharging a solution in the form of primary mist and a convergent ultrasonic wave generating means for converting the solution into ultrafine mist; and a powder recovery unit including a heating gas supply means for heating the ultrafine mist and a separation recovery means for separating and recovering a vaporized solvent and a solute. The convergent ultrasonic wave generating means is provided with a plurality of vibration plates in the vicinity of the discharge port of the mist discharge means, and the vibration plates are vibrated with ultrasonic waves in the same phase to generate a directional ultrasonic sound flow in the vertical direction from each surface of the vibration plates. The plurality of vibration plates are arranged so that the directional direction of each ultrasonic sound flow is converged in the front in the discharge direction of the primary mist discharged from the discharge port of the mist discharge means.

Description

Technical Field

[0001] The present invention relates to a spray drying device for separating a solute and a solvent from a solution and recovering the solute as fine particle powder, and more particularly to a spray drying device capable of avoiding denaturation, decomposition, deterioration, etc. of a solute component.

Background Art

[0002] Conventionally, as a method for producing a dried product from a solution or a slurry, there is a spray dryer (also referred to as a spray drier) for producing a dried product under high temperature conditions. However, since the conventionally used spray dryer usually performs drying in a high temperature atmosphere of 150°C or higher, there has been a problem that the solute dissolved in the solution is denatured, decomposed, or deteriorated due to the high temperature. In particular, in fields such as pharmaceutical production and food production, it is often necessary to handle heat-sensitive components such as proteins, vitamins, and pharmaceuticals, and it has been difficult to dry them without these denaturation, decomposition, and deterioration.

[0003] On the other hand, in order to avoid denaturation, decomposition, and deterioration, a method of drying at a low temperature of -180 to -10°C (freeze-drying method) is also performed. However, in the freeze-drying method, the drying time is long, it is difficult to obtain a sufficient dried product, and there are also problems with the stability of the operation. In addition, the equipment used in the freeze-drying method is large-scale, and there are also problems with equipment costs and running costs.

[0004] Therefore, in Patent Document 1 below, a spray dryer has been proposed that can avoid denaturation, decomposition, deterioration, etc. of the solute component and can reduce equipment costs and running costs. In this spray dryer, the liquid to be dried atomized by an ultrasonic atomizing device is sprayed into a vacuum chamber, dried by heating means provided on the side surface in the vacuum chamber, and the fine particles are separated and recovered by a dust collecting device.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the above Patent Document 1, since the liquid to be dried is atomized by an ultrasonic atomizer and then dried, it seems to be drying of fine particles and the drying is likely to be carried out rapidly. Also, the temperature in the vacuum chamber is said to be as low as 20 to 80°C during operation, and it also seems that denaturation, decomposition, deterioration, etc. of the solute component can be avoided. However, the surface temperature of the heating means provided on the side surface in the vacuum chamber is not clear, and because vacuum is used, heat conduction is poor and heat from the heating means is not easily transmitted. Also, the mist of the atomized liquid to be dried may adhere to and deposit on the heating means in the vacuum chamber, and heat denaturation, decomposition, deterioration, etc. may occur on this surface. Also, the equipment costs of the vacuum chamber itself and the decompression equipment are also a problem.

[0007] Therefore, in response to the above various problems, the present invention aims to provide a spray drying apparatus that can make the drying temperature low and the drying time short by making the solution, which is the liquid to be dried, into ultrafine mist, and can prevent the ultrafine mist from adhering to and depositing on the inner wall surface of the apparatus, avoid denaturation, decomposition, deterioration, etc. of the solute component, and obtain fine and uniform fine particle powder.

Means for Solving the Problems

[0008] In solving the above problems, as a result of intensive research, the inventors of the present invention have found that by atomizing the solution, which is the liquid to be dried, and applying a converging ultrasonic acoustic flow thereto, it becomes an ultrafine mist that is further refined, and thus the present invention has been completed. The numbers in parentheses described in each of the following claims are reference numerals indicating each component of the embodiment according to the present invention.

[0009] That is, according to the description of claim 1, the spray drying apparatus (10) according to the present invention An ultrasonic spray unit (20) that converts a solution composed of a solute of a solid component and a solvent of a liquid component into an ultrafine mist (26) and supplies it, and a powder recovery unit (30) that vaporizes the solvent from the supplied ultrafine mist and recovers the solute as fine powder, The ultrasonic spray unit includes a mist discharging means (50) that converts the solution into a primary mist (25) and discharges it, and a converging ultrasonic generating means (60) that further refines the primary mist and converts it into an ultrafine mist. The powder recovery unit includes a heating gas supply means that supplies a heating gas for heating the ultrafine mist, and a separation and recovery means (40) that separates the vaporized solvent and the solute and recovers the solute. The converging ultrasonic generating means includes a plurality of diaphragm plates (61a to 61d) near the discharge port of the mist discharging means, and ultrasonically vibrates the plurality of diaphragm plates in the same phase to generate ultrasonic directional acoustic flows (62a to 62d) in the vertical direction from each plate surface. By arranging the plurality of diaphragm plates so that the directional directions of the respective ultrasonic acoustic flows converge in front of the discharge direction of the primary mist discharged from the discharge port of the mist discharging means, The primary mist discharged from the discharge port of the mist discharging means is converted into an ultrafine mist, and the ultrafine mist is supplied to the powder recovery unit by the pressure of the converged ultrasonic acoustic flow.

[0010] Further, according to the description of claim 2, the present invention is a spray drying apparatus according to claim 1, The mist discharging means is characterized in that it is a mist generator by a spray nozzle such as a one-fluid nozzle or a two-fluid nozzle, a rotary spray device, or an ultrasonic atomizing device such as a nebulizer.

[0011] Further, according to the description of claim 3, the present invention is a spray drying apparatus according to claim 1 or 2, The separation and recovery means consists of a cyclone separator, which introduces the heating gas supplied from the heating gas supply means from the tangential direction of the inner wall of the cyclone body. The heating gas and the ultrafine mist come into contact with each other due to the vortex flow, exchange heat, evaporate the solvent, and separate the mixed gas of the heating gas and the vaporized solvent from the solid solute.

[0012] Further, according to the description of claim 4, the present invention is a spray drying apparatus according to claim 3, The separation and recovery means ultrasonically vibrates a plurality of vibrating plates (41a to 41d) arranged facing the disk surface at the central part of the upper inner wall surface of the cyclone body, and generates ultrasonic acoustic flows (42a to 42d) in the vertical direction from each disk surface by ultrasonic waves. By applying pressure from the surroundings to the ultrafine mist supplied to the cyclone body by the ultrasonic acoustic flow, the fine state of the ultrafine mist is maintained, and the vaporization of the solvent is promoted.

Advantages of the Invention

[0013] According to the above configuration, the spray drying apparatus according to the present invention has an ultrasonic spray unit and a powder recovery unit. The ultrasonic spray unit converts a solution composed of a solid component solute and a liquid component solvent into an ultrafine mist and supplies it. The powder recovery unit vaporizes the solvent from the supplied ultrafine mist and recovers the solute as fine powder. The ultrasonic spray unit includes a mist discharging means for converting the solution into a primary mist and discharging it, and a converging ultrasonic wave generating means for further refining the primary mist into an ultrafine mist. The powder recovery unit includes a heating gas supply means for supplying a heating gas for heating the ultrafine mist, and a separation and recovery means for separating the vaporized solvent and the solute and recovering the solute.

[0014] In such a configuration, the converging ultrasonic generating means includes a plurality of diaphragms near the discharge port of the mist discharging means, and ultrasonically vibrates the plurality of diaphragms in the same phase to generate a directivity ultrasonic acoustic flow in the vertical direction from each disk surface by ultrasonic waves. The plurality of diaphragms are arranged so that the directivity directions of these ultrasonic acoustic flows converge in front of the discharge direction of the primary mist discharged from the discharge port of the mist discharging means. Thereby, the primary mist discharged from the discharge port of the mist discharging means is converted into ultrafine mist, and the ultrafine mist is supplied to the powder recovery unit by the pressure of the converging ultrasonic acoustic flow.

[0015] Thus, according to the above configuration, by making the solution, which is the liquid to be dried, into ultrafine mist, the drying temperature can be lowered and the drying time can be shortened. At the same time, the ultrafine mist does not adhere and deposit on the inner wall surface of the device, so that denaturation, decomposition, deterioration, etc. of the solute component can be avoided, and a spray drying device capable of obtaining fine and uniform fine particle powder can be provided.

[0016] Also, according to the above configuration, the mist discharging means may be a mist generator using a spray nozzle such as a one-fluid nozzle or a two-fluid nozzle, a rotary spray device, or an ultrasonic atomization device such as a nebulizer. Thereby, the above-described effects can be more specifically exhibited.

[0017] Also, according to the above configuration, the separation and recovery means includes a cyclone separator, and the heating gas supplied from the heating gas supply means is introduced from the tangential direction of the inner wall of the cyclone body. Due to the vortex of the introduced heating gas, the heating gas and the ultrafine mist come into contact and exchange heat to evaporate the solvent. Then, the mixed gas of the heating gas and the vaporized solvent and the solid solute are separated. Thereby, the above-described effects can be more specifically exhibited.

[0018] Further, according to the above configuration, the separation and recovery means ultrasonically vibrates a plurality of vibrating plates arranged facing the disk surface at the central portion of the upper inner wall surface of the cyclone main body to generate an ultrasonic acoustic flow in the vertical direction from each disk surface by ultrasonic waves. The pressing force by this ultrasonic acoustic flow is applied to the ultrafine mist supplied to the cyclone main body from the surroundings. By this, the fine state of the ultrafine mist is maintained and the vaporization of the solvent is promoted. Thereby, the above-described operational effects can be more specifically exhibited.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0020] In the spray drying apparatus according to the present invention, the solute and the solvent can be separated from a solution composed of a solute of a solid component and a solvent of a liquid component, and the solute can be recovered as fine and uniform fine particle powder. In particular, unlike a conventional spray dryer that requires a drying process at a high temperature for a long time, denaturation, decomposition, deterioration, etc. of the solute component do not occur. Therefore, it functions effectively when handling heat-sensitive components such as proteins, vitamins, and pharmaceuticals in fields such as pharmaceutical manufacturing and food manufacturing. Further, it can also be used for natural product extraction extracts, fragrances, powder oils, pigments, chemical products, or inorganic substances, etc.

[0021] Before explaining the spray drying apparatus according to the present invention, the term "mist" in the present invention will be explained. In the present invention, when simply referred to as "mist", it is interpreted in a broad sense and includes a state in which liquid droplets are atomized and suspended in the air, a state in which gas and liquid droplets are mixed, and a state in which a phase change between condensation and evaporation is repeated between gas and liquid droplets. In the present invention, when explaining such a broad concept of "mist" in detail, it is classified into "primary mist" and "ultrafine mist" according to the particle size of the main components constituting the mist.

[0022] First, the "primary mist" referred to in the present invention does not only include particles of 10 μm or less generally defined as mist, but also includes "fine droplets" having a larger particle size and particles of 5 μm or less generally defined as fog.

[0023] Examples of primary mist generation means include a one-fluid spray nozzle that directly atomizes a liquid, a piezo high-pressure injection device, a disk-type atomizer, a disk mesh-type atomizer, etc. There are also ejectors and two-fluid spray nozzles that atomize a liquid with high-pressure air or the like. When these are used, not only particles of 10 μm or less but also many "fine droplets" are included.

[0024] On the other hand, when using ultrasonic vibration action such as a nebulizer or an ultrasonic atomizer as the primary mist generation means, particles of 10 μm or less are the main component (mainly but not all). Thus, there are mainly two types of mist in the "primary mist" referred to in the present invention depending on the difference in the primary mist generation means used. As will be described later, in the present invention, it is preferable to use the action of ultrasonic vibration as the primary mist generation means.

[0025] On the one hand, the "ultrafine mist" referred to in the present invention means that the primary mist is homogenized into ultrafine particles of 3 μm or less, which are finer and contain fog of 5 μm or less, under the action of a converging ultrasonic wave generating means (details will be described later), and this is the main component (mainly but not all). Since the particle size of this ultrafine mist is extremely small, its surface area is large, and the phase change between condensation and evaporation is actively repeated between the gas and the mist. Therefore, under the action of an external heat source (heating gas), the evaporation of the solvent is promoted, and the solute and the solvent can be easily separated.

[0026] Hereinafter, the spray drying apparatus according to the present invention will be described in detail with reference to specific embodiments. It should be noted that the present invention is not limited only to the following embodiments.

[0027] FIG. 1 is a front view showing the appearance of the spray drying apparatus according to the present invention. In FIG. 1, the spray drying apparatus 10 has an ultrasonic spray unit 20 and a powder recovery unit 30 (details will be described later). Outside the ultrasonic spray unit 20, a solution tank 21, a supply pump 22, and a supply pipe 23 for supplying a solution to a mist discharge means (not shown, to be described later) are provided. The structure of the ultrasonic spray unit 20 will be described later.

[0028] The powder recovery unit 30 has a heating gas supply means (not shown) and a separation and recovery means 40. The separation and recovery means 40 is a cyclone separator, which is composed of a straight cylindrical mist drying part 40a at the upper part and a spindle-shaped separation part 40b at the lower part. At the upper part of the mist drying part 40a, an introduction pipe 43 for introducing the heating gas from the heating gas supply means into the interior is provided. The heating gas is introduced from this introduction pipe 43 in a tangential direction to the inner wall of the mist drying part 40a to form a vortex inside. This vortex exhibits the function of the cyclone separator.

[0029] On the peripheral wall of the mist drying section 40a, four vibrating plates 41a to 41d (41d is not shown in the figure) are provided at equal intervals. Each vibrating surface of these vibrating plates 41a to 41d is arranged from the inner wall surface of the mist drying section 40a toward the center. The functions of the four vibrating plates 41a to 41d will be described later.

[0030] In the lower part of the separation section 40b, a cyclone separation mechanism separates solids (solute) from gas (a mixed gas of vaporized solvent and heating gas), and a discharge pipe 44 for discharging the mixed gas to the outside is provided. The mixed gas discharged from the discharge pipe 44 to the outside is cooled by a heat exchanger and separated into a heating gas (details will be described later) and a solvent as a liquid component, and each is recovered. Further, below the separation section 40b, a recovery container 45 for recovering the recovered solute powder (fine particle powder) is provided.

[0031] Next, the structure and function of the ultrasonic spray unit 20 will be described. FIG. 2 is a perspective view of a conceptual configuration diagram showing the inside of the ultrasonic spray unit. In FIG. 2, the ultrasonic spray unit 20 has a mist discharge means 50 and a converging ultrasonic generation means 60. In FIG. 2, the cylindrical outer wall 20a of the ultrasonic spray unit 20 is shown in a perspective state.

[0032] In the present embodiment, an ultrasonic atomizer 50 (only the discharge port is shown in FIG. 2) is adopted as the mist discharge means 50, which receives the solution 24 sent from the solution tank 21 via the supply pipe 23, converts it into fine primary mist 25, and discharges it from the discharge port. Therefore, the primary mist 25 is a fine mist mainly composed of particles of 10 μm or less (mainly but not all).

[0033] The converging ultrasonic generation means 60 is composed of four vibrating plates 61a to 61d arranged on the upper part of the inner side wall surface of the cylindrical outer wall 20a of the ultrasonic spray unit 20 so as to surround the discharge port of the ultrasonic atomizer 50. Here, the distance from the discharge port of the ultrasonic atomizer 50 to each of the vibrating plates 61a to 61d is not particularly limited.

[0034] In this embodiment, as the four vibrating plates 61a to 61d, ultrasonic transmitters (DC12V, 50 mA) with superdirectivity that transmit ultrasonic waves in the vicinity of a frequency of 40 kHz were all used. Note that the number of vibrating plates may be two or more, preferably a plurality of three or more. Also, regarding the type, number, size, structure, output, etc. of the ultrasonic transmitters arranged on each vibrating plate, there is no particular limitation. Further, in this embodiment, there is no particular limitation regarding the ultrasonic wave generation mechanism, frequency range, output, etc. in the ultrasonic transmitter.

[0035] The four vibrating plates 61a to 61d that transmit superdirective ultrasonic waves are attached at an inward angle with respect to each other in front of (below the discharge port) on the discharge axis of the discharge port of the ultrasonic atomization device 50 located at the center so that the ultrasonic acoustic flow due to ultrasonic vibration converges. Here, the inward angle refers to an attachment angle such that the elevation angle of the ultrasonic acoustic flow is greater than 0° and less than 90° with respect to the discharge axis of the discharge port of the ultrasonic atomization device 50, and preferably an attachment angle such that it is 45° or more and 70° or less.

[0036] Note that in this embodiment, the four vibrating plates 61a to 61d are ultrasonically vibrated in the same phase to generate directive ultrasonic acoustic flows 62a to 62d by ultrasonic waves in the vertical direction from each plate surface. Also, the transmission directions from each plate surface are converged in front of (below the discharge port) on the discharge axis of the discharge port of the ultrasonic atomization device 50. As a result, the ultrasonic acoustic flows 62a to 62d emitted from each of the vibrating plates 61a to 61d reinforce each other at the focal point 63 (convergence site 63), and the maximum energy is concentrated at this site.

[0037] From this, the fine primary mist 25 of the solution 24 discharged downward from the discharge port of the ultrasonic atomization device 50 to below the ultrasonic spraying unit 20 will obtain the maximum energy of the concentrated ultrasonic acoustic flow, and will be further refined into the ultrafine mist 26 of the solution 24. Further, the energy of the converged ultrasonic acoustic flow forms the ultrafine mist 26 and acts on the ultrafine mist 26 to press the ultrasonic acoustic flow in the mist traveling direction (downward in the figure). As a result, the ultrafine mist 26 is pushed out in the direction of arrow 26a and is introduced into the powder recovery unit 30 connected to the lower part of the ultrasonic spraying unit 20.

[0038] In this way, since the ultrafine mist 26 of the solution 24 introduced into the powder recovery unit 30 has a small particle size and a large surface area, the evaporation efficiency of the mist is high and evaporation and condensation are actively repeated. As a result, in the powder recovery unit 30, the ultrafine mist 26 is affected by the heating gas introduced from the outside, and the solvent can be easily vaporized to separate the solute and the solvent. Note that the action of the ultrasonic acoustic flows 62a to 62d can suppress the adhesion of the mist not only to the ultrafine mist of the solution but also to the discharge port of the ultrasonic atomization device 50 and the inner wall surface of the ultrasonic spraying unit 20.

[0039] Next, the structure and function of the powder recovery unit 30 will be described. As described above, the powder recovery unit 30 has a heating gas supply means (not shown) and a separation and recovery means 40. FIG. 3 is a conceptual configuration diagram showing the inside of the powder recovery unit, which is (A) a front view and (B) a cross-sectional view taken along line X-X. In FIG. 3(A), the separation and recovery means 40 is a cyclone separator, which is composed of a straight cylindrical mist drying part 40a at the upper part and a spindle-shaped separation part 40b at the lower part.

[0040] Four diaphragm disks 41a to 41d (41d is not shown in the figure) are provided at equal intervals on the peripheral wall of the mist drying part 40a. Each vibration surface of these diaphragm disks 41a to 41d is arranged from the inner wall surface of the mist drying part 40a toward the center.

[0041] In this embodiment, as the four diaphragms 41a to 41d, ultrasonic transducers (DC12V, 50mA) with superdirectivity that transmit ultrasonic waves in the vicinity of a frequency of 40 kHz were used. Note that the number of diaphragms is not limited to four and is not particularly limited. Also, regarding the type, number, size, structure, output, etc. of the ultrasonic transducers arranged on each diaphragm, there is no particular limitation. Further, in this embodiment, there is no particular limitation on the ultrasonic generation mechanism, frequency range, output, etc. of the ultrasonic transducers.

[0042] Each ultrasonic acoustic flow generated by the ultrasonic vibration of the four diaphragms 41a to 41d is attached with the wave transmission direction of each diaphragm facing the central part of the cylinder so as to converge at the central part of the cylinder of the mist drying part 40a. As a result, the ultrasonic acoustic flows 42a to 42d emitted from the respective diaphragms 41a to 41d reinforce each other at the central part of the cylinder, and the maximum energy is concentrated at this part (see Fig. 3(B)).

[0043] In such a configuration, the ultrafine mist 26 that has been pushed into the inside of the mist drying part 40a (arrow 26a) by the pressing of the ultrasonic acoustic flow from an ultrasonic spray unit (not shown) obtains the maximum energy at which the ultrasonic acoustic flows 42a to 42d are concentrated. The ultrafine mist does not coalesce with each other, and further refinement of the mist and evaporation of the solvent are promoted.

[0044] At the same time, heating gas from a heating gas supply means (not shown) is introduced into the upper part of the mist drying part 40a through the introduction pipe 43. In Fig. 3(B), the introduction pipe 43 is opened so as to discharge the heating gas from the tangential direction of the inner wall of the mist drying part 40a. As a result, the introduced heating gas forms a vortex 46 along the inner wall of the mist drying part 40a. This vortex 46 exhibits the function of a cyclone separator. Also, since this vortex 46 flows downward along the inner wall of the mist drying part 40a, the ultrafine mist does not adhere and deposit on the inner wall surface of the powder recovery unit 30.

[0045] Here, the heating gas will be described. The heating gas acts to impart thermal energy to the ultrafine mist to be dried and evaporate the solvent from the solution constituting the ultrafine mist. Generally, it is good to use heated air, but depending on the properties of the solute and solvent to be heated, an inert gas such as nitrogen or argon may be used as necessary. In this embodiment, heated air is adopted for the purpose of manufacturing fine particles of pharmaceuticals. The temperature of the heated air is set to 100°C or lower, preferably 80°C, in order to avoid deterioration of the pharmaceuticals. Note that the temperature of the heating gas may be set in consideration of the properties of the object to be dried.

[0046] In this embodiment, the reason why the temperature of the heating gas for drying can be set low and the drying time can also be shortened is considered as follows. The solution to be dried receives the energy concentrated by the ultrasonic acoustic flow and is refined into ultrafine particles, with its particle size being small and its surface area being large. Due to this, the evaporation efficiency of the ultrafine mist becomes high, and it is considered that the solvent easily vaporizes under the action of the heating gas. As a result, the solute and the solvent can be easily separated. Note that the action of the ultrasonic acoustic flows 42a to 42d can suppress not only the separation of the solute and the solvent but also the adhesion and deposition of the dried solute on the inner wall surface of the powder recovery unit 30.

[0047] In the separation part 40b of the spindle cylinder provided at the lower part of the mist drying part 40a, the ultrafine mist 26 and the heating gas are heat-exchanged while being vigorously mixed and contacted by the vortex 46 of the heating gas, and are separated into a solid (solute) and a gas (a mixed gas of the vaporized solvent and the heating gas). The separated solute is recovered as fine particle powder 47 in a recovery container 45 provided below the separation part 40b. In this embodiment, the fine particle powder 47 recovered from the ultrafine mist 26 is a uniform and fine powder, and its particle size can be recovered to be about 5 μm to 0.1 μm.

[0048] On the other hand, the solvent is recovered as a mixed gas with the heating gas from the central part (reference numeral 44a in FIG. 3(B)) of the cyclone separation mechanism of the mist drying section 40a through the conduit 44. The recovered mixed gas is cooled by a heat exchanger and separated into the heating gas and the liquid component of the solvent, which are respectively recovered and reused. The heat exchanger, which is the solvent recovery facility, is a common one and will not be described here.

[0049] As described above, according to the present embodiment, by making the solution, which is the liquid to be dried, into ultrafine mist, the drying temperature can be lowered and the drying time can be shortened. In addition, the ultrafine mist does not adhere and deposit on the inner wall surface of the apparatus, so that denaturation, decomposition, deterioration, etc. of the solute component can be avoided, and a spray drying apparatus capable of obtaining fine and uniform fine particle powder can be provided.

[0050] In the implementation of the present invention, various modifications as follows can be cited, not limited to the above embodiment. (1) In the above embodiment, an ultrasonic atomization device was used as the mist discharging means to supply the primary mist. However, the present invention is not limited to this, and a one-fluid spray nozzle, a piezo high-pressure injection device, a disk-type atomization device, a disk mesh-type atomization device, an ejector, a two-fluid spray nozzle, etc. that do not use ultrasonic waves may be used. (2) In the above embodiment, four diaphragm plates were provided on the peripheral wall of the mist drying section to further apply an ultrasonic acoustic flow to the ultrafine mist. However, the present invention is not limited to this, and a normal cyclone separator may be used without providing a diaphragm plate. (3) In the above embodiment, a cyclone separation mechanism was adopted for the recovery of the solute. However, the present invention is not limited to this, and other separation mechanisms such as a filter may be adopted.

Explanation of reference numerals

[0051] 10... Spray drying apparatus, 20... Ultrasonic spray unit, 20a... Cylindrical outer wall, 21... Solution tank, 22... Supply pump, 23... Supply pipe, 24... Solution, 25... Primary mist, 26... Ultrafine mist, 30... Powder recovery unit, 40... Separation and recovery means, 40a... Mist drying part, 40b... Separation part, 41a~41d... Vibration plates, 42a~42d... Ultrasonic sound streams, 43... Introduction pipe, 44... Outlet pipe, 45... Recovery container, 46... Vortex, 47... Fine particle powder, 50... Mist discharge means (ultrasonic atomizer), 60... Converging ultrasonic generation means, 61a~61d... Vibration plates, 62a~62d... Ultrasonic sound streams, 63... Focus (convergence site).

Claims

1. An ultrasonic spray unit that converts a solution composed of a solute as a solid component and a solvent as a liquid component into an ultrafine mist and supplies it, and a powder recovery unit that vaporizes the solvent from the supplied ultrafine mist and recovers the solute as fine powder, The ultrasonic spray unit includes a mist discharge means that converts the solution into a primary mist and discharges it, and a converging ultrasonic wave generation means that further refines the primary mist and converts it into an ultrafine mist, The powder recovery unit includes a heating gas supply means that supplies a heating gas for heating the ultrafine mist, and a separation and recovery means that separates the vaporized solvent and the solute and recovers the solute, The converging ultrasonic wave generation means includes a plurality of diaphragm plates near the discharge port of the mist discharge means, and ultrasonically vibrates the plurality of diaphragm plates in the same phase to generate a directional ultrasonic acoustic flow in the vertical direction from each plate surface, and arranges the plurality of diaphragm plates so that the directional directions of the respective ultrasonic acoustic flows converge in front of the discharge direction of the primary mist discharged from the discharge port of the mist discharge means, An atomization drying device characterized in that the primary mist discharged from the discharge port of the mist discharge means is converted into an ultrafine mist, and the ultrafine mist is supplied to the powder recovery unit by the pressure of the converged ultrasonic acoustic flow.

2. The mist discharge means is a mist generator by a spray nozzle such as a one-fluid nozzle or a two-fluid nozzle, a rotary atomization device, or an ultrasonic atomization device such as a nebulizer, according to the atomization drying device described in Claim 1.

3. The separation and recovery means consists of a cyclone separator, and the heating gas supplied from the heating gas supply means is introduced from the tangential direction of the inner wall of the cyclone body, and the heating gas and the ultrafine mist come into contact and exchange heat by the vortex to evaporate the solvent, and the mixed gas of the heating gas and the vaporized solvent and the solid solute are separated, according to the atomization drying device described in Claim 1 or 2.

4. The separation and recovery means ultrasonically vibrates a plurality of diaphragm plates arranged facing the plate surface at the center of the upper inner wall surface of the cyclone body to generate an ultrasonic acoustic flow by ultrasonic waves in the vertical direction from each plate surface, An atomization drying device characterized in that by applying pressure by ultrasonic acoustic flow from the surroundings to the ultrafine mist supplied to the cyclone body, the fine state of the ultrafine mist is maintained and the vaporization of the solvent is promoted, according to the atomization drying device described in Claim 3.

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