Dried particle producing apparatus and method for producing dried particles

Abstract

To provide an apparatus for producing dried particles, which has a short freeze-drying time because the particle size distribution of frozen particles is narrow, and can suppress the deterioration of a vacuum state in a vacuum drying part when the frozen particles are moved from a spray freezing part to the vacuum drying part.SOLUTION: A spray freezing section 10 that has a nozzle for spraying a raw material liquid to form droplets of the raw material liquid and freezes the droplets under normal pressure and in a freezing atmosphere to form frozen particles, a vacuum drying section 20 that dries the frozen particles in a vacuum atmosphere to form dried particles, and a frozen particle transferring section 30 that transfers the frozen particles to the vacuum drying section 20, the frozen particle transfer part 30 is provided with a pressure regulating chamber 31 in which a supply port 41 and a discharge port 43 of the frozen particles are formed and which has a first opening / closing valve 51 for opening / closing the supply port and a second opening / closing valve 53 for opening / closing the discharge port, and a pressure reducing means 33 connected to the pressure regulating chamber 31 through a connection valve 35 to reduce the pressure in the pressure regulating chamber 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dry particle manufacturing apparatus and a dry particle manufacturing method, and more particularly to a dry particle manufacturing apparatus and a dry particle manufacturing method that can shorten the freeze-drying time by narrowing the particle size distribution of frozen particles and further suppress deterioration of the vacuum state in the vacuum drying section. [Background technology]

[0002] Conventionally, dry microparticles have been produced for the purpose of dry powdering of biopharmaceuticals and molding and sintering fine ceramics, etc. Such dry microparticles can be produced, for example, by spraying a raw material liquid into a cryogenic airflow using an atmospheric pressure spray dryer to form frozen particles, or by spraying a raw material liquid into liquid nitrogen to form frozen particles, and then transferring the frozen particles to a batch-type (e.g., rotary drum or static) vacuum freeze dryer for vacuum freeze-drying (MERIDION (product name) from Powrex Corporation, Pris Co., Ltd., Professor Niwa of Meijo University, Associate Professor Monda of Osaka University of Pharmaceutical Sciences).

[0003] On the other hand, batch-type drum rotary or agitator tank vacuum freeze-drying devices have been developed and are commercially available, which spray and freeze raw liquid under vacuum conditions. Specifically, in Japan, ULVAC, Kyowa Vacuum Engineering, Hosokawa Micron, and Kobelco Eco-Solutions are developing and selling these devices.

[0004] More recently, MII Inc. has proposed a continuous spray freeze-drying apparatus (i.e., an apparatus that spray-freezes a raw material liquid under vacuum and then dries it in a rotary retort under vacuum) (see Patent Document 1). Okawara Kakoki Co., Ltd., the applicant of the present application, has received a license to use the patent rights for this apparatus.

[0005] Furthermore, there has also been reported an apparatus in which a raw material liquid is sprayed and frozen to obtain frozen particles, and then the frozen particles are transferred to a vacuum drying chamber and dried (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6777350 [Patent Document 2] Special Publication No. 2007-535652 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when spraying a raw material liquid into a vacuum, as in the device described in Patent Document 1, freezing occurs at the tip of the spray nozzle, and there are still many issues to be resolved, such as how to maintain the vacuum in a multi-fluid nozzle. In other words, it cannot be handled in the same way as spraying a raw material liquid under normal pressure, making it difficult to adequately control the spray particles. Specifically, the particle size distribution becomes broad, the average particle size cannot be adequately controlled, and many large frozen pieces are mixed in. This results in a problem of freeze-drying times being several to several tens of times longer than when many large frozen pieces are not mixed in.

[0008] Furthermore, there is known a device such as that described in Patent Document 2, which sprays and freezes a raw material liquid under normal pressure to obtain frozen particles, and then moves these frozen particles to a vacuum drying chamber for drying. However, when the frozen particles are moved from a normal pressure atmosphere to a vacuum atmosphere, there is a problem in that the freezing state of the particles changes in the vacuum drying section (i.e., the freezing level decreases).

[0009] Therefore, there was a strong need for the development of a dried particle manufacturing device that could avoid the particle size distribution of frozen particles becoming wider due to the inclusion of coarse frozen pieces, thereby shortening the freeze-drying time, and further, could suppress a decrease in the freezing level of particles in the drying area (vacuum drying area) in a vacuum atmosphere when transferring frozen particles from the spray freezing area (spray freezing section) in an atmospheric pressure atmosphere to the drying area (vacuum drying section).

[0010] The present invention has been made to solve the problems of the prior art as described above, and provides a dried particle manufacturing apparatus and a dried particle manufacturing method that have a short freeze-drying time due to the narrow particle size distribution of the frozen particles, and that can reduce fluctuations in particle temperature (i.e., suppress a decrease in the freezing level of the particles) when moving the frozen particles from a spray-freezing area (spray-freezing section) in an atmospheric pressure atmosphere to a drying area (vacuum drying section) in a vacuum atmosphere, and can suppress a decrease in the vacuum state in the drying area (vacuum drying section). [Means for solving the problem]

[0011] The present invention provides the following dry particle manufacturing apparatus and dry particle manufacturing method.

[0012] [1] A spray freezing unit having a nozzle that sprays a raw material liquid to form droplets of the raw material liquid, and that freezes the droplets under normal pressure and a refrigerated atmosphere to form frozen particles; a vacuum drying section for drying the frozen particles in a vacuum atmosphere to form dried particles; a frozen particle transfer unit that transfers the frozen particles to the vacuum drying unit, The frozen particle transfer unit includes: a pressure adjustment chamber in which a supply port and a discharge port for the frozen particles are formed, the pressure adjustment chamber having a first on-off valve for opening and closing the supply port and a second on-off valve for opening and closing the discharge port; a pressure reducing means connected to the pressure adjusting chamber via a connecting valve, for reducing the pressure inside the pressure adjusting chamber.

[0013] [2] The apparatus for producing dried particles according to [1], wherein the pressure reducing means comprises a pressure reducing chamber that is reduced in pressure below the pressure in the pressure adjusting chamber, and a pressure reducing pump that reduces the pressure inside the pressure reducing chamber.

[0014] [3] The apparatus for producing dried particles according to [2] above, wherein the ratio of the internal volume of the decompression chamber to the internal volume of the pressure adjustment chamber (internal volume of the decompression chamber / internal volume of the pressure adjustment chamber) is 5 to 100.

[0015] [4] The apparatus for producing dried particles according to any one of [1] to [3] above, further comprising an external cooling and insulation means for cooling and insulating the inside of the pressure adjusting chamber.

[0016] [5] A cold air generating unit connected to the spray freezing unit; The dry particle manufacturing apparatus according to any one of [1] to [3] above, further comprising a circulation unit that collects the cold air in the spray freezing unit, cools it using the cold air generation unit, and returns it to the spray freezing unit.

[0017] [6] The apparatus for producing dried particles according to [5], wherein the circulation unit has a cleaning means for cleaning the cold air.

[0018] [7] The dried particle manufacturing apparatus according to any one of [1] to [3], wherein the vacuum drying section has a particle cooling and insulating means for cooling and insulating the frozen particles, and a heating means for heating the particles in the vacuum drying section.

[0019] [8] The apparatus for producing dried particles according to any one of [1] to [3], wherein the vacuum drying section is a retort rotary type vacuum drying section, a vibration conveyor type vacuum drying section, or a belt conveyor type vacuum drying section.

[0020] [9] A method for producing dry particles using the dry particle production apparatus according to any one of [1] to [3], a freezing step of forming the frozen particles by the spray freezing unit; a first transfer step of opening the first on-off valve of the pressure adjustment chamber in the frozen particle transfer unit, supplying the frozen particles from the supply port to the pressure adjustment chamber, and closing the first on-off valve; a decompression step of opening the connecting valve after closing the first on-off valve in the first transfer step, thereby reducing the pressure inside the pressure adjustment chamber by communicating the pressure adjustment chamber with the decompression means, and then closing the connecting valve; a second transfer step of opening the second on-off valve of the pressure adjustment chamber after closing the connecting valve, and discharging the frozen particles from the outlet of the pressure adjustment chamber to the vacuum drying section; a drying step of drying the frozen particles discharged from the pressure adjusting chamber in the vacuum drying section to form dried particles. [Effects of the Invention]

[0021] The dried particle manufacturing apparatus of the present invention has a narrow particle size distribution of frozen particles, resulting in a short freeze-drying time.Furthermore, when the frozen particles are moved from the spray-freezing region (spray-freezing section) in an atmospheric pressure atmosphere to the drying region (vacuum drying section) in a vacuum atmosphere, it is possible to reduce fluctuations in particle temperature (i.e., to prevent a decrease in the freezing level of the particles), and to prevent a decrease in the vacuum state in the drying region (vacuum drying section) in a vacuum atmosphere.As a result, the amount of vacuum exhaust can be reduced, and the vacuum pump can be made more power-efficient and energy-efficient.

[0022] According to the method for producing dried particles of the present invention, the particle size distribution of the frozen particles is narrowed and the freeze-drying time is shortened.Furthermore, when the frozen particles are moved from the spray-freezing region (spray-freezing section) in an atmospheric pressure atmosphere to the drying region (vacuum drying section) in a vacuum atmosphere, the fluctuation in particle temperature in the drying region (vacuum drying section) in a vacuum atmosphere can be reduced (i.e., the increase in particle temperature can be suppressed), and the deterioration of the vacuum state in the drying region (vacuum drying section) in a vacuum atmosphere can be suppressed.As a result, the amount of vacuum exhaust can be reduced, and the vacuum pump can be made more power-efficient and energy-efficient. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an explanatory diagram schematically illustrating one embodiment of an apparatus for producing dry particles according to the present invention. [Figure 2] 2 is an explanatory view schematically illustrating one embodiment of a pressure adjusting chamber in the dry particle manufacturing apparatus shown in FIG. 1. FIG. [Figure 3] FIG. 2 is an explanatory view schematically illustrating one embodiment of a method for producing dry particles using the dry particle production apparatus shown in FIG. [Figure 4] FIG. 2 is an explanatory view schematically illustrating one embodiment of a method for producing dry particles using the dry particle production apparatus shown in FIG. [Figure 5] FIG. 2 is an explanatory view schematically illustrating one embodiment of a method for producing dry particles using the dry particle production apparatus shown in FIG. [Figure 6] FIG. 2 is an explanatory view schematically illustrating one embodiment of a method for producing dry particles using the dry particle production apparatus shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments. In other words, it should be understood that modifications and improvements to the following embodiments, based on the ordinary knowledge of a person skilled in the art, as long as they do not deviate from the spirit of the present invention, also fall within the scope of the present invention.

[0025] (1)Dry particle production equipment: One embodiment of the dry particle manufacturing apparatus of the present invention is a dry particle manufacturing apparatus 100 shown in Fig. 1. This dry particle manufacturing apparatus 100 includes a spray-freezing unit 10 having a nozzle that sprays a raw material liquid to form droplets of the raw material liquid and freezes the droplets under normal pressure and a refrigerated atmosphere to form frozen particles, a vacuum drying unit 20 that dries the frozen particles under a vacuum atmosphere to form dried particles, and a frozen particle transfer unit 30 that transfers the frozen particles to the vacuum drying unit 20. As shown in Fig. 2, the frozen particle transfer unit 30 includes a pressure adjustment chamber 31 formed with a supply port 41 and a discharge port 43 for frozen particles, the pressure adjustment chamber 31 having a first on-off valve 51 that opens and closes the supply port 41 and a second on-off valve 53 that opens and closes the discharge port 43, and a pressure reduction means 33 connected to the pressure adjustment chamber 31 via a connecting valve and that reduces the pressure inside the pressure adjustment chamber 31. The dry particle manufacturing apparatus 100 also includes a raw material tank 11 that supplies the raw material liquid to the nozzle of the spray-freezing unit 10 via a liquid feed pump (not shown).

[0026] This dried particle manufacturing apparatus 100 utilizes the knowledge gained from conventional devices that spray at atmospheric pressure. The narrow particle size distribution of the frozen particles shortens the freeze-drying time. Furthermore, when the frozen particles are transferred from the atmospheric spray-freezing region (spray freezing section 10) to the vacuum drying region (vacuum drying section 20), the frozen state of the particles is prevented from changing in the vacuum drying section, thereby minimizing deterioration of the vacuum state in the vacuum drying region (vacuum drying section 20). Furthermore, because the frozen state of the particles is prevented from changing, temperature fluctuations in the particles are small, preventing an increase in ice crystals in the frozen particles and ensuring more consistent quality of the resulting dried particles. As a result, a decrease in the freezing level of the particles increases the number of ice crystals in the frozen particles. This increase in ice crystals tends to result in a decrease in the quality of the resulting dried particles. Furthermore, by minimizing deterioration of the vacuum state in the vacuum drying region (vacuum drying section), the amount of vacuum exhaust is reduced, resulting in reduced power and energy consumption of the vacuum pump.

[0027] In this specification, "normal pressure" specifically means a pressure of about 101 kPa±10 kPa.

[0028] The dried particle manufacturing apparatus 100 can continuously produce a constant amount of dried particles by intermittently transferring the frozen particles sprayed with the raw material liquid from the nozzle at short intervals. In other words, the transfer time from the spray freezing section 10 to the vacuum drying section 20 (the time spent in the frozen particle transfer section 30) can be, for example, about 30 seconds. For example, if the vacuum drying time is 45 minutes, 90 dried particles will be discharged during this 45-minute drying time (the residence time in the vacuum drying section 20). This can be said to be "continuous" production. While the raw material liquid is continuously sprayed from the nozzle as described above, the transfer time for each transfer is shortened. This reduces the amount of frozen particles deposited at the supply port 41 of the pressure adjusting chamber 10, facilitating continuous production.

[0029] The dry particle manufacturing apparatus 100 can manufacture dry particles for food, medicine, health food, and the like.

[0030] (1-1) Spray freezing part: The spray freezing unit 10 has a nozzle that sprays the raw liquid to form droplets of the raw liquid, and freezes the droplets under normal pressure and a refrigerated atmosphere to form frozen particles. Because this spray freezing unit 10 forms frozen particles under normal pressure, it has the advantage of being able to produce frozen particles with a narrow particle size distribution (obtaining a powder with a more uniform particle size) compared to forming frozen particles in a vacuum, as in Patent Document 1, for example. Furthermore, using this spray freezing unit 10 makes it less likely for coarse frozen pieces to be mixed in, thereby shortening the freeze-drying time.

[0031] This spray freezing section 10 can be suitably adapted from a spray freezing machine used in a conventionally known spray freezing (cooling) granulation device.

[0032] The average particle size of the droplets of the raw material liquid is not particularly limited and can be set appropriately depending on the intended use of the dried particles, but can be, for example, 400 μm or less, more preferably 200 μm or less, even more preferably about 50 to 150 μm, and even more preferably about 30 to 100 μm.

[0033] In order to make the droplets have the above average particle size, it is advisable to appropriately select and employ a nozzle such as a two-fluid nozzle.

[0034] The amount of the liquid material to be sprayed (amount of liquid supplied) is not particularly limited, but may be, for example, 1 to 5000 ml / min, and preferably 1 to 1000 ml / min.

[0035] The interior of the spray freezing unit 10 is a frozen atmosphere, and the droplets sprayed from the nozzle are exposed to this frozen atmosphere, causing the water to freeze and become frozen particles. The temperature within the spray freezing unit 10 is not particularly limited, but it is preferable that cold air of -15°C or below be supplied into the spray freezing unit 10 to form the frozen atmosphere. The temperature of the supplied cold air is preferably -20°C, more preferably -30 to -100°C, and particularly preferably -40 to -70°C. By supplying cold air at or below the above temperature to form a frozen atmosphere, the solidification (freezing) of the sprayed droplets becomes uniform, i.e., the number of coarse particles and amorphous particles is reduced. This shortens the drying time of the frozen particles, allowing the freeze-drying unit to be made smaller.

[0036] The temperature inside the spray freezing section 10 (temperature of the freezing atmosphere) can be set to -5°C or below, which is close to the temperature of the supplied cold air, and is more preferably -5 to -100°C, and particularly preferably -10 to -30°C.

[0037] (1-2) Vacuum drying section: The vacuum drying section 20 dries the frozen particles in a vacuum atmosphere to produce dried particles. A dryer used in a conventionally known continuous vacuum drying apparatus for particles (particulate matter) can be appropriately adopted as the vacuum drying section 20.

[0038] The vacuum is the same as that in a conventionally known vacuum freeze-drying device. Specifically, it can be a pressure condition of about 0.6 kPa or less. More specifically, the vacuum drying section 20 can be set to 1 to 600 Pa.

[0039] The temperature inside the vacuum drying section 20 can be set to -40 to +60°C, preferably -20 to +60°C, and more preferably -20 to +50°C.

[0040] The vacuum drying section 20 can be, for example, a retort rotary vacuum drying section, a vibrating conveyor vacuum drying section, or a belt conveyor vacuum drying section. Any of these vacuum drying sections can be used, but using a vibrating conveyor vacuum drying section reduces contamination and allows for large-volume processing. FIG. 1 shows a vibrating conveyor vacuum drying section 20, and this vibrating conveyor vacuum drying section 20 and the frozen particle transfer section 30 are connected via a bellows piping 21. This bellows piping 21 absorbs vibrations generated by the vibrating conveyor vacuum drying section 20 and prevents the vibrations from being transmitted to the frozen particle transfer section 30.

[0041] Furthermore, the vacuum drying unit 20 may have a particle insulated / cooling means (not shown) for insulating and cooling the frozen particles, and a heating means (not shown) for heating the particles in the vacuum drying unit 20. In particular, the particle insulated / cooling means is preferably used in the first half of the vacuum drying unit 20, i.e., to prevent the frozen particles from thawing when they are supplied from the frozen particle transfer unit 30. Furthermore, the heating means is preferably used in the middle to latter half of the drying process of the frozen particles in the vacuum drying unit 20, i.e., when water has sublimated from the frozen particles and they are in a state close to powder, to promote drying.

[0042] Examples of particle cooling and insulation means include heat insulation using the heat of self-sublimation, a refrigerant jacket, and a cold air jacket.

[0043] Examples of the heating means include a hot water jacket, a hot air jacket, and an electric heater.

[0044] (1-3) Frozen particle transfer section: As shown in Fig. 1, the frozen particle transfer section 30 transfers frozen particles 60 (see Fig. 3, etc.) formed in the spray freezing section 10 to the vacuum drying section 20. The frozen particle transfer section 30 is provided with a pressure adjustment chamber 31 in which a supply port 41 and a discharge port 43 for the frozen particles 60 are formed, and which has a first on-off valve 51 for opening and closing the supply port 41 and a second on-off valve 53 for opening and closing the discharge port 43, and a pressure reduction means 33 connected to the pressure adjustment chamber 31 via a connecting valve 35 and for reducing the pressure inside the pressure adjustment chamber 31.

[0045] By providing this frozen particle transfer section 30, frozen particles can be continuously transferred to the vacuum drying section 20 while remaining frozen. Furthermore, when transferring frozen particles from the spray freezing section 10, which is an atmospheric pressure atmosphere, to the vacuum drying section 20, which is a vacuum atmosphere, a decrease in the vacuum state (temporary increase in pressure) in the vacuum drying section 20 can be suppressed. Specifically, when a conventional on-off valve such as a vacuum lock (vacuum valve) is used to transfer frozen particles from the spray freezing section to the vacuum drying section by appropriately opening and closing this on-off valve, the pressure in the vacuum drying section temporarily increases (rapidly fluctuates) when this on-off valve is opened. Such large pressure fluctuations within the vacuum drying section can cause particles that move too quickly during transfer to scatter, increase the ice crystals in the frozen particles, or melt the interior of the frozen particles, potentially degrading the resulting powder (dried particles).

[0046] (1-3a) Pressure adjustment room: As shown in Figures 1 and 2, the pressure adjustment chamber 31 is formed with a supply port 41 and a discharge port 43 for frozen particles 60, and has a first on-off valve 51 that opens and closes the supply port 41 and a second on-off valve 53 that opens and closes the discharge port 43. This pressure adjustment chamber 31 forms a space into which the frozen particles formed in the spray freezing unit 10 are temporarily introduced before being supplied to the vacuum drying unit 20. When the frozen particles are introduced into this pressure adjustment chamber 31, the pressure is the same as that of the spray freezing unit 10 (normal pressure), but after the frozen particles are introduced, the pressure is reduced to a predetermined level. Specifically, the pressure inside the pressure adjustment chamber 31 is normal when the frozen particles are supplied, and is preferably 20 kPa or less when the frozen particles are discharged. More preferably, it is 5 kPa or less.

[0047] In this way, the inside of the pressure adjustment chamber 31 is a buffer region where normal pressure atmosphere and reduced pressure atmosphere are alternately alternated. By providing this pressure adjustment chamber 31, the reduced pressure atmosphere and the reduced pressure atmosphere (vacuum atmosphere) come into contact with each other even when the frozen particles are transferred from the pressure adjustment chamber 31 to the vacuum drying section 20. This makes it possible to suppress an increase in pressure inside the vacuum drying section 20, and reduces pressure fluctuations inside the vacuum drying section 20.

[0048] The first on-off valve 51 opens and closes the supply port 41 of the pressure adjustment chamber 31, and at this time, it is preferable to open and close the supply port 41 in a sealed state.

[0049] There are no particular restrictions on the material of the part of the first on-off valve 51 that comes into contact with the supply port 41, as long as it can open and close the supply port 41 of the pressure adjustment chamber 31, but examples of materials that can be used include silicone rubber and Teflon (registered trademark).

[0050] The second on-off valve 53 opens and closes the discharge port 43 of the pressure adjustment chamber 31, and at this time, it is preferable that the discharge port 43 is opened and closed in a sealed state. As with the first on-off valve 51, there are no particular restrictions on the material of the part of the second on-off valve 53 that comes into contact with the discharge port 43, as long as it can open and close the discharge port 43 of the pressure adjustment chamber 31. Examples of materials that can be used include silicone rubber and Teflon (registered trademark).

[0051] The second on-off valve 53 may be the same as the first on-off valve 51, or may be different.

[0052] (1-3b) Pressure reduction means: The pressure reducing means 33 is connected to the pressure adjusting chamber 31 via a connecting valve 35 and reduces the pressure inside the pressure adjusting chamber 31. By connecting the pressure reducing means 33 to the pressure adjusting chamber 31, the pressure inside the pressure adjusting chamber 31 is reduced from normal pressure to a pressure that is approximately the same as or several tens of times (i.e., 10 Pa to 10 kPa) the pressure inside the vacuum drying section 20. The pressure inside the vacuum drying section 20 can be set to 700 Pa or less. Specifically, even if the pressure momentarily rises to approximately 700 Pa when transferring frozen particles, the pressure inside the vacuum drying section 20 is maintained at approximately 70 Pa except during this transfer.

[0053] The connecting valve 35 opens and closes the flow path between the pressure adjusting chamber 31 and the pressure reducing means 33, and any conventionally known opening and closing valve can be appropriately adopted.

[0054] The pressure reducing means 33 is not particularly limited as long as it can reduce the pressure inside the pressure adjusting chamber 31, but for example, as shown in Fig. 1, it is preferable that the pressure reducing means 33 includes a pressure reducing chamber 37 that is reduced in pressure below the pressure inside the pressure adjusting chamber 31, and a pressure reducing pump 39 that reduces the pressure inside the pressure adjusting chamber 37. By adopting such a configuration, the pressure inside the pressure adjusting chamber 31 can be reduced to the desired pressure quickly. Furthermore, since the pressure can be reduced to the desired pressure quickly, the transfer interval can be shortened, and the moisture contained in the dried particles can be made more uniform.

[0055] 5, when the connecting valve 35 is opened to connect the pressure reducing means 33 to the pressure adjusting chamber 31, it is preferable to maintain a vacuum state within the pressure reducing chamber 37, specifically, a pressure of 1 kPa or less. This allows the device to be made smaller and also allows the pressure within the pressure adjusting chamber 31 to be reduced to the desired pressure more quickly.

[0056] Here, the value of the internal volume ratio between the pressure reduction chamber 37 and the pressure adjustment chamber 31 in the pressure reduction means 33 (i.e., internal volume of the pressure reduction chamber 37 / internal volume of the pressure adjustment chamber 31) is not particularly limited, but is preferably, for example, 5 to 100, more preferably 5 to 50, particularly preferably 10 to 40, and most preferably 10 to 30. By setting it within the above range, the pressure inside the pressure adjustment chamber 31 can be reduced to the desired pressure particularly quickly.

[0057] (1-4) Other structures: The dried particle manufacturing apparatus 100 can further include a cold air generation unit 61 connected to the spray freezing unit 10, and a circulation unit 63, which is a pipe for circulating cold air that collects the cold air in the spray freezing unit 10, cools it using the cold air generation unit 61, and returns it to the spray freezing unit 10. By further including a cold air circulation mechanism in this way, the energy required to cool the inside of the spray freezing unit 10 can be reduced.

[0058] Furthermore, it is more preferable that the circulation unit 63 has a cleaning means 65 for cleaning the cold air. In the dried particle production apparatus 100 shown in Fig. 1, a blower fan 67 for forming a flow of cold air in the cold air circulation mechanism is disposed between the cleaning means 65 and the cold air generation unit 61.

[0059] A specific example of the cleaning means 65 is a bag filter.

[0060] The dried particle manufacturing apparatus 100 may further include a particle collector 69 for collecting the frozen particles formed in the spray freezing section 10. Examples of this particle collector 69 include an airflow reversal type collector and a cyclone type collector, and by using a particle collector 69 such as a cyclone type collector, the formed frozen particles can be efficiently collected.

[0061] The dried particle manufacturing apparatus 100 may have an external cooling means 70 (see FIG. 2) that keeps the inside of the pressure adjustment chamber 31 cool and insulates the inside of the pressure adjustment chamber 31. By providing this external cooling means 70, it is possible to more reliably prevent the frozen particles supplied into the pressure adjustment chamber 31 from melting. Note that the external cooling means 70 is not shown in any figures other than FIG. 2.

[0062] The external refrigeration means 70 is not particularly limited, but examples thereof include a refrigerant jacket through which a refrigerant passes, a refrigerant tracing pipe, and a refrigerator filled with a refrigerant and a heat insulating material.

[0063] The dry particle production apparatus 100 includes a dry particle recovery device 71 (see FIG. 1) that is connected to the vacuum drying section 20 and recovers dry particles via a split valve or the like (not shown). In this dry particle recovery device 71, the dry particles can be filled into a recovery container under reduced pressure, for example.

[0064] More specifically, in the dried particle recovery device 71, dried particles can be filled into a recovery container (such as a stainless steel container) as follows. First, dust-free nitrogen is introduced through the lid of the recovery container below a split valve or the like to create a normal pressure inside the vacuum drying section 20 and the recovery container. Then, the recovery container is removed to the outside via a split valve or the like. This is done after waiting for the accumulation and flying of powder to subside for powders with low bulk density that tend to become powdery before removing them. The removal frequency can be about every 10 minutes.

[0065] (2) Method for producing dried particles: The method for producing dried particles of the present invention is a method for producing dried particles using the dried particle production apparatus of the present invention. The method for producing dried particles of the present invention includes a freezing step of forming frozen particles using a spray freezing unit 10, a first transfer step of opening a first on-off valve 51 of a pressure adjustment chamber 31 in a frozen particle transfer unit 30, supplying frozen particles to the pressure adjustment chamber 31 through a supply port 41, and closing the first on-off valve 51, a depressurization step of closing the first on-off valve 51 in the first transfer step, opening a connecting valve 35 to connect the pressure adjustment chamber 31 to a depressurization means 33, reducing the pressure inside the pressure adjustment chamber 31, and closing the connecting valve 35, a second transfer step of closing the connecting valve 35, opening a second on-off valve 53 of the pressure adjustment chamber 31, and discharging the frozen particles from an outlet 43 of the pressure adjustment chamber 31 to a vacuum drying unit 20, and a drying step of drying the frozen particles discharged from the pressure adjustment chamber 31 in the vacuum drying unit 20 to form dried particles.

[0066] According to this method for producing dried particles, the particle size distribution of the frozen particles is narrowed and the freeze-drying time is shortened.Furthermore, when the frozen particles are moved from the spray-freezing area (spray-freezing section 10) in an atmospheric pressure atmosphere to the drying area (vacuum drying section 20) in a vacuum atmosphere, the fluctuation in particle temperature in the drying area (vacuum drying section) in a vacuum atmosphere can be reduced (i.e., the increase in particle temperature can be suppressed), and the deterioration of the vacuum state in the drying area (vacuum drying section 20) in a vacuum atmosphere can be suppressed.As a result, the amount of vacuum exhaust can be reduced, and the vacuum generation equipment (especially the vacuum pump) can be made more power-efficient, smaller, and more energy-efficient.

[0067] (2-1) Freezing process: The freezing process is a process in which frozen particles 60 (see FIG. 3) are formed by the spray freezing section 10. FIG. 3 shows the frozen particles 60 accumulating at the supply port 41 of the pressure adjustment chamber 31 in the frozen particle transfer section 30. The frozen particles 60 formed in this process are produced in a spray freezing region (spray freezing section 10) in an atmospheric pressure atmosphere, and therefore, compared to using a spray freezer in a reduced pressure atmosphere, it is possible to select appropriate conditions from a wide variety of liquid atomizers according to the processing amount and the properties of the raw material liquid (i.e., there are more atomizer options), and by selecting a more appropriate atomizer, it is possible to obtain particles with a narrow particle size distribution and a uniform particle diameter.

[0068] The average particle size of the droplets of the raw liquid sprayed in the spray freezing section 10 is not particularly limited and can be set appropriately depending on the intended use of the dried particles, but can be, for example, 400 μm or less, more preferably 200 μm or less, and even more preferably about 50 to 150 μm, and particularly about 30 to 100 μm. The spray rate of the raw liquid (supply rate) is not particularly limited, but can be, for example, 1 to 5000 ml / min, preferably 1 to 1000 ml / min.

[0069] As mentioned above, it is preferable that cold air of -15°C or below is supplied to the spray freezing section 10, and furthermore, the temperature of the cold air supplied is preferably -20°C or below, more preferably -30 to -100°C, and particularly preferably -40 to -70°C.

[0070] The temperature inside the spray freezing section 10 (temperature of the freezing atmosphere) can be set to -5°C or below, which is close to the temperature of the supplied cold air, and is more preferably -5 to -100°C, and particularly preferably -10 to -30°C.

[0071] (2-2) First transfer process: The first transfer step is a step of opening the first on-off valve 51 of the pressure adjustment chamber 31 in the frozen particle transfer section 30, supplying frozen particles to the pressure adjustment chamber 31 through the supply port 41 (see FIGS. 3 and 4), and closing the first on-off valve 51. As shown in FIG. 4, if the supply port 41 of the pressure adjustment chamber 31 is formed on the top surface of the pressure adjustment chamber 31, the frozen particles will flow into the pressure adjustment chamber 31 due to their own weight when the first on-off valve 51 is opened. If the discharge port 43 of the pressure adjustment chamber 31 is formed on the bottom surface of the pressure adjustment chamber 31, the frozen particles that have flowed into the pressure adjustment chamber 31 will accumulate near the discharge port 43 (see FIG. 5).

[0072] (2-3) Decompression step: The decompression step is a step in which, after closing the first on-off valve 51 in the first transfer step, the connecting valve 35 is opened, the pressure adjustment chamber 31 and the decompression means 33 are connected to each other, the pressure inside the pressure adjustment chamber 31 is reduced (see FIG. 5), and the connecting valve 35 is closed. Figure 5 shows a device that includes a decompression chamber 37 that is reduced in pressure below the pressure inside the pressure adjustment chamber 31, and a decompression pump 39 that maintains the decompression state inside this decompression chamber 37. In this step, the air inside the pressure adjustment chamber 31 flows into the decompression means 33 (decompression chamber 37) and is decompressed.

[0073] At this time, if the ratio of the internal volume of the pressure reduction chamber 37 to the internal volume of the pressure adjustment chamber 31 in the pressure reduction means 33 (i.e., the internal volume of the pressure reduction chamber 37 / the internal volume of the pressure adjustment chamber 31) is, for example, 5 to 100, the pressure in the pressure adjustment chamber 31 will be reduced (specifically, a vacuum state will be created) quickly.

[0074] (2-4) Second transfer process: The second transfer step is a step in which, after closing the connecting valve 35, the second on-off valve 53 of the pressure adjustment chamber 31 is opened, and the frozen particles are discharged from the outlet 43 of the pressure adjustment chamber 31 to the vacuum drying section 20, as shown in Fig. 6. When the second on-off valve 53 of the pressure adjustment chamber 31 is opened in this manner, the pressure inside the pressure adjustment chamber 31 is reduced to a pressure close to the pressure inside the vacuum drying section 20, and the effect on the vacuum drying section 20 (pressure fluctuations inside the vacuum drying section 20) caused by opening the second on-off valve 53 of the pressure adjustment chamber 31 can be reduced.

[0075] When the second on-off valve 53 of the pressure adjustment chamber 31 is opened, the frozen particles flow into the vacuum drying section 20 from the discharge port 43 due to their own weight.

[0076] (2-5) Drying process: The drying step is a step of forming dried particles by drying the frozen particles discharged from the pressure adjusting chamber 31 in the vacuum drying section 20. In this step, the frozen particles are dried to obtain dried particles.

[0077] As described above, the vacuum drying section 20 may be, for example, a retort rotary type vacuum drying section, a vibration conveyor type vacuum drying section, or a belt conveyor type vacuum drying section.

[0078] The drying time can be set appropriately depending on the particle size of the frozen particles, and for example, when the average particle size is 300 μm, it is about 1 hour.

[0079] The temperature inside the vacuum drying section 20 can be set to -40 to +60°C, preferably -20 to +60°C, and more preferably -20 to +50°C.

[0080] The pressure inside the vacuum drying section 20 is a pressure in a vacuum state, and specifically, can be set to 0.6 kPa (600 Pa) or less, more specifically, 1 to 600 Pa.

[0081] In the vacuum drying section 20, the frozen particles can be prevented from melting by employing a particle cooling means. In addition, the use of a heating means can accelerate drying when the water has evaporated from the frozen particles and they are in a state close to powder.

[0082] The dried particles can be collected by a collection device 71 (see FIG. 1) connected to the vacuum drying section 20. [Example]

[0083] EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

[0084] Example 1 A dry particle production apparatus as shown in FIG. 1 was prepared, and dry particles (specifically, mannitol powder, average particle diameter 120 μm) were produced using this dry particle production apparatus.

[0085] Specifically, first, frozen particles are formed in the spray freezing section (freezing process). The frozen particles obtained in the freezing process are supplied to the pressure adjustment chamber through a supply port by opening a first on-off valve in the pressure adjustment chamber in the frozen particle transfer section, and the first on-off valve is closed (first transfer process). After closing the first on-off valve in the first transfer process, the connecting valve is opened, the pressure adjustment chamber is connected to the pressure reduction means, the pressure inside the pressure adjustment chamber is reduced, and the connecting valve is closed (depressurization process). After closing the connecting valve, the second on-off valve in the pressure adjustment chamber is opened, and the frozen particles are discharged from the discharge port of the pressure adjustment chamber to the vacuum drying section (second transfer process).

[0086] At this time, almost no change in the internal pressure was observed in the spray-freezing area.

[0087] Thereafter, the frozen particles discharged from the pressure adjusting chamber were dried in a vacuum drying section to form dried particles, and at this time the internal pressure of the vacuum drying section was kept at 600 Pa or less (drying step).

[0088] As described above, with the dried particle manufacturing apparatus of Example 1, the particle size distribution of the frozen particles is narrowed, thereby shortening the freeze-drying time, and furthermore, when the frozen particles are moved from the spray-freezing region (spray-freezing section) in an atmospheric pressure atmosphere to the drying region (vacuum drying section) in a vacuum atmosphere, it is possible to suppress a decrease in the vacuum state in the drying region (vacuum drying section) in a vacuum atmosphere. [Industrial Applicability]

[0089] The dry particle production apparatus of the present invention can be used as an apparatus for producing dry particles. Also, the dry particle production method of the present invention can be employed as a method for producing dry particles. [Explanation of symbols]

[0090] 10: spray freezing section, 11: raw material tank, 20: vacuum drying section, 21: bellows piping, 30: frozen particle transfer section, 31: pressure adjustment chamber, 33: pressure reduction means, 35: connecting valve, 37: pressure reduction chamber, 39: pressure reduction pump, 41: supply port, 43: discharge port, 51: first on-off valve, 53: second on-off valve, 60: frozen particles, 61: cold air generation section, 63: circulation section, 65: purification means, 67: blower fan, 69: particle recovery machine, 70: external refrigeration cooling means, 71: dried particle recovery device, 100: dried particle manufacturing apparatus.

Claims

1. a spray freezing unit having a nozzle for spraying a raw material liquid to form droplets of the raw material liquid, and freezing the droplets under normal pressure and a refrigerated atmosphere to form frozen particles; a vacuum drying section for drying the frozen particles in a vacuum atmosphere to form dried particles; a frozen particle transfer unit that transfers the frozen particles to the vacuum drying unit, The frozen particle transfer unit includes: a pressure adjustment chamber in which a supply port and a discharge port for the frozen particles are formed, the pressure adjustment chamber having a first on-off valve for opening and closing the supply port and a second on-off valve for opening and closing the discharge port; a pressure reducing means connected to the pressure adjusting chamber via a connecting valve, for reducing the pressure inside the pressure adjusting chamber.

2. 2. The apparatus for producing dry particles according to claim 1, wherein the pressure reducing means comprises a pressure reducing chamber whose pressure is reduced below the pressure inside the pressure adjusting chamber, and a pressure reducing pump that reduces the pressure inside the pressure reducing chamber.

3. 3. The apparatus for producing dried particles according to claim 2, wherein a ratio of the internal volumes of the decompression chamber and the pressure adjustment chamber (internal volume of the decompression chamber / internal volume of the pressure adjustment chamber) is 5 to 100.

4. 4. The apparatus for producing dried particles according to claim 1, further comprising an external cooling / insulating means for cooling and insulating the inside of the pressure adjusting chamber.

5. A cold air generating unit connected to the spray freezing unit; The dry particle manufacturing apparatus according to any one of claims 1 to 3, further comprising a circulation unit that collects cold air from the spray freezing unit, cools it using the cold air generating unit, and returns it to the spray freezing unit.

6. 6. The apparatus for producing dry particles according to claim 5, wherein the circulation unit has a cleaning means for cleaning the cold air.

7. The dried particle manufacturing apparatus according to any one of claims 1 to 3, wherein the vacuum drying section has a particle cooling and insulating means for cooling and insulating the frozen particles, and a heating means for heating the particles in the vacuum drying section.

8. The dried particle manufacturing apparatus according to any one of claims 1 to 3, wherein the vacuum drying section is a retort rotation type vacuum drying section, a vibration conveyor type vacuum drying section, or a belt conveyor type vacuum drying section.

9. A method for producing dry particles using the dry particle production apparatus according to any one of claims 1 to 3, a freezing step of forming the frozen particles by the spray freezing unit; a first transfer step of opening the first on-off valve of the pressure adjustment chamber in the frozen particle transfer unit, supplying the frozen particles from the supply port to the pressure adjustment chamber, and closing the first on-off valve; a decompression step of opening the connecting valve after closing the first on-off valve in the first transfer step, thereby reducing the pressure inside the pressure adjustment chamber by communicating the pressure adjustment chamber with the decompression means, and then closing the connecting valve; a second transfer step of opening the second on-off valve of the pressure adjustment chamber after closing the connecting valve, and discharging the frozen particles from the outlet of the pressure adjustment chamber to the vacuum drying section; a drying step of drying the frozen particles discharged from the pressure adjusting chamber in the vacuum drying section to form dried particles.

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