JPH07121354B2 - Granular dried product manufacturing method and vacuum freeze-drying apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a granular or powdery dried product from an aqueous solution of a drug, food, chemical or the like, and a vacuum freeze-drying apparatus used for carrying out the method. Regarding

This type of granular dried product manufacturing method and vacuum freeze-drying device,
For example, in the field of obtaining a granular or powdery dried product from an aqueous solution of cells that are easily killed by heat such as lactic acid bacteria and bifidobacteria, or from an aqueous solution of protease, lipase and other heat-sensitive enzymes in granular or powdery form. Field to obtain dried products of
Or, antibiotics, crude drugs, bioactive substances, vitamins,
Field of obtaining granular or powdery dried products from aqueous solutions of pharmaceuticals or chemicals such as amino acids, or aqueous solutions of foods such as seasonings, fruit juices, sweeteners, favorite beverages, dairy products, various extracts, etc. It can be used in the field of obtaining a dried product in the form of granules or powder.

[Prior art]

Conventionally, as a method and an apparatus for obtaining a granular or powdery dried product from the above various aqueous solutions, a method and an apparatus for freeze-drying such an aqueous solution as it is in a vacuum tank have been used. As a heating method for drying in the vacuum tank, a method of conducting or radiant heating using a heating shelf in which a heating medium such as heating oil, hot water, steam is circulated is generally adopted. It had been.

[Problems to be solved by the invention]

In the case of the above-described conventional drying method and apparatus, since a large amount of water in the aqueous solution is frozen as it is, there is a large amount of water to be sublimated, a large amount of energy needs to be supplied, and a great amount of time is required for the drying process. Was becoming. In addition, in the above-described conventional heating method, the temperature distribution of the heating shelf is likely to be non-uniform due to the circulation structure of the heating medium and the like, and there is a risk of uneven drying of the dried product.

[Means for solving problems]

In view of the above problems, it is an object of the present invention to provide a method for efficiently producing a granular or powdery high quality dried product from an aqueous solution raw material, and a vacuum freeze-drying apparatus used for carrying out the method.

According to the present invention, a step of irradiating the aqueous solution raw material with far-infrared rays in a depressurized concentration tank to concentrate the aqueous solution raw material, and a step of ice-freezing the concentrated raw material to produce a frozen granular material to be dried, And a step of irradiating a far-infrared ray on a granular dried material in a vacuum tank to sublimate water in the dried material to dry the granular dried material.

Further, according to the present invention, a vacuum freeze-drying device for use in carrying out the method for producing a granular dried material, comprising a vacuum tank for drying the granular material to be dried, and being connected to the vacuum tank. A vacuum evacuation means for evacuating the inside of the vacuum chamber to a vacuum, and a cold trap device for condensing and collecting water in the exhaust.
A material to be dried supply means for supplying the frozen granular material to be dried into the vacuum tank, a far infrared ray irradiation means for irradiating the frozen granular material to be dried in the vacuum device with far infrared rays, and a vacuum tank There is provided a vacuum freeze-drying device comprising a discharging means for discharging the dried granules.

[Work]

In general, when removing the same amount of water from an aqueous solution raw material, concentration under reduced pressure can be performed with a smaller amount of heat than freeze-drying under vacuum. In the present invention, the aqueous solution raw material is concentrated under reduced pressure, and the concentrated liquid or slurry raw material is freeze-dried under vacuum. Therefore, the amount of water to be sublimated can be reduced, and it is necessary to generate a dried product. It will save the total energy.

Moreover, in the concentration step, since the aqueous solution raw material in the concentration tank is heated by the radiant heating by far infrared rays, it is possible to efficiently supply energy and save energy in the concentration step. Further, in the drying step, since the material to be dried in the frozen state is granular, the heat receiving surface area of the material to be dried in the vacuum tank, that is, the sublimation surface area is increased, and the drying time can be shortened. Further, since the moisture inside the material to be dried is easily sublimated, unevenness in drying hardly occurs, and a high quality dried material can be obtained. Moreover, since the material to be dried in the vacuum tank is heated and dried by radiant heating using far infrared rays, it is possible to efficiently supply energy and save energy in the drying process.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the overall configuration in which a far infrared heating type vacuum concentration device 10, an ice maker 40, and a vacuum freeze-drying device 50 used for carrying out the method for producing a granular dried product according to the present invention are connected.

First, a description will be given of a first configuration example of the far-infrared heating type vacuum concentration device 10 shown in FIG. 1. The far-infrared heating type vacuum concentration device includes a concentration tank 11 capable of withstanding a reduced pressure.
11 is a condenser via a pressure reducing pipe 12 equipped with an exhaust valve 13 in the middle
It is connected to 14. The condenser 14 is provided with a condensing pipe 14a cooled by the refrigerant from the condensing cooling device 15, and the condensing pipe 14a condenses the steam generated in the concentrating tank 11. The condenser 14 is connected to a pressure reducing device 17 such as a vacuum pump via a pressure reducing pipe 16. Decompression device
17 has the ability to keep the degree of vacuum inside the concentration tank 11 at, for example, 10 to 100 Torr.

A stock solution pipe 18 for supplying an aqueous solution raw material, that is, a stock solution A into the concentrate tank 11 is connected to the concentration tank 11, and the stock solution pipe 18 is connected to a stock solution tank 20 via a stock solution supply pump 19.
Moreover, in order to discharge the stock solution A concentrated to a predetermined concentration to the outside of the concentration tank 11, the concentration tank 11 is connected to the concentration tank 24 via the storage chamber 21 and the discharge switching valves 22 and 23 before and after the storage chamber 21. There is. By alternately opening and closing the switching valves 22 and 23, the concentrated stock solution A in liquid or slurry form can be taken out of the concentration tank 11 while preventing the vacuum degree in the concentration tank 11 from decreasing.

Inside the concentration tank 11, a plurality of trays 25 (six in the illustrated configuration example) for allowing the undiluted solution A supplied into the concentration tank 11 to flow down naturally are arranged in a multi-tiered manner in the vertical direction. The stock solution A is supplied from the stock solution pipe 18 to the tray 25 at the first stage, that is, the uppermost stage. The tray 25 has the form of a dish-shaped container with a large opening upward. The number of trays 25 can be appropriately selected depending on the amount of the stock solution A to be processed, the required evaporation amount, and the like.

Undiluted solution A due to evaporation of water while flowing down along tray 25
In order to make the liquid depth of the stock solution A in the tray 25 constant with respect to the decrease of
A circulation device 26 that circulates the undiluted solution A from the tray 25 of the (stage) to the tray 25 of the first stage is provided. In the illustrated configuration example, a combination of a circulating liquid pump 27 and a circulating liquid pipe 28 is used as the circulating device 26.

Further, in the illustrated configuration example, the vibrating and conveying device 29 is provided on the tray 25 below the tray 25 for extracting the circulating liquid. By vibrating the tray 25, the vibrating and conveying device 29 plays a role of forcibly flowing down the concentrated stock solution A slurried in the tray 25 or crystals precipitated from the concentrated stock solution A. The tray 25 on which the vibrating and conveying device 29 should be provided can be appropriately selected according to the degree of slurrying of the stock solution A and the like.

Above the tray 25, a far-infrared radiator 30 for irradiating the undiluted solution A in the tray 25 with far-infrared rays and heating the far-infrared rays is arranged.
In the illustrated configuration example, the far-infrared radiator 30 has a rod shape, but a plate-shaped, lamp-shaped, or other shape can be used, and the far-infrared radiators 30 of these various shapes can be combined appropriately. It can also be used. When using the rod-shaped or lamp-shaped far-infrared radiator 30, the far-infrared reflector 31 can be used.

In the illustrated configuration example, a plurality of rod-shaped far-infrared ray radiators 30 are arranged in parallel with the lower surface of the stock solution of the tray 25 and in parallel with the downflow direction of the undiluted solution A at intervals. A reflector 31 is arranged so as to cover almost the upper half of the projectile 30. The far infrared rays reflected by the reflector 31 are applied to the surface of the stock solution A in the tray 25.

Although the illustration of the internal structure is omitted, the far-infrared radiator 30
Has an outer shell containing a heat source inside. The outer shell can be made of ceramic, but may have a structure in which a ceramic sprayed coating film is formed on the outer surface of the outer shell made of metal. As the ceramic used for the far infrared radiator 30, any one or two of aluminum, magnesium, chromium, silicon, zirconium, beryllium, lithium, titanium, vanadium, iron, cobalt, nickel, antimony and tin is used. The above oxides can be used.

As the heating source of the far infrared radiator 30, that is, a primary heating element, an electric heater such as a nichrome wire heater, steam, combustion gas, etc. can be used, but the heating source leaks due to deterioration of the outer shell of the radiator 30. From the viewpoint of preventing the above and improving the accuracy of temperature control, an electric heater is used in the illustrated configuration example.

The liquid temperature of the stock solution A in the tray 25 is slightly lower than the saturation temperature at which the degree of vacuum in the concentration tank 11 is the saturated vapor pressure, for example, 10
It is desirable to maintain at ~ 50 ° C. For this purpose, in the illustrated configuration example, temperature control for detecting the surface temperature of the far-infrared radiator 30 by each sensor 33 and controlling the heat load (here, the current supplied to the electric heater) by the far-infrared radiator 30. A device 32 is provided connected to the far infrared radiator 30. Here, the temperature of the far-infrared radiator 30 is controlled based on the temperature detection by the single sensor 33, but the surface temperature of the far-infrared radiator 30 at each stage is made by a plurality of sensors. The far infrared radiator 30 is detected for each step.
The temperature control may be performed.

When the stock solution A is concentrated under reduced pressure by the far-infrared heating type vacuum concentration apparatus having the above structure, first, the condensation cooling device 15
And the inside of the concentrating tank 11 is maintained at a vacuum degree of, for example, 60 Torr by operating the decompression device 17.

Then, the stock solution supply pump 19 is operated to supply the stock solution A in the stock solution tank 20 to the uppermost tray 25 in the concentration tank 11 by the pump 19. Simultaneously with the supply of the stock solution A, the far-infrared radiator 30 is caused to generate heat, and the circulating liquid pump 27 and the vibration transfer device 29 are operated. The far-infrared radiator 30 is controlled by the temperature controller 32 so that the liquid temperature of the stock solution A in the tray 25 is kept at, for example, 40 ° C.

While the stock solution A naturally flows down in the multi-stage tray 25, the far-infrared radiator 30 irradiates the stock solution A with far-infrared rays effective for evaporation of water. As a result, the water content in the stock solution A is evaporated and the stock solution A is concentrated. The water evaporated from the stock solution A is condensed by the condenser 14. A part of the stock solution A is a circulating fluid pump
Circulated by 27.

The concentrated stock solution A is stored in the concentrated solution tank 24 through the storage chamber 21 and the discharge switching valves 22 and 23 before and after the storage chamber 21.

According to the working conditions as exemplified above, for example, a solution containing various amino acids (concentration 3 wt%) can be reduced to 10 vol% (amino acid concentration 30 wt%) by continuous treatment of about 40 l / Hr, and good quality is achieved. It was confirmed that a concentrated solution was obtained. The resulting concentrate has excellent stability and can be stored for a long period of time.

2 and 3 show the second example of the far infrared heating type vacuum concentration device.
It shows a configuration example. In these figures, the first
The same components as those in the configuration example are designated by the same reference numerals. In this second configuration example, as shown in detail in FIG. 3, the tray 25 has the ceramic sprayed coating film 25a on at least the contact surface with the stock solution A, and the first or uppermost tray 25 Far infrared radiator 30 above
The far infrared reflector 30 is provided only for the. As the ceramic used for the tray 25, the same material as the ceramic for the far infrared radiator 30 described above can be used.

Therefore, the undiluted solution A in the tray 25 of the second and subsequent stages is not only irradiated with far infrared rays from the far infrared radiator 30 above it, but also the tray 25 itself due to heat from the far infrared radiator 30 below the tray 25. Becomes a far-infrared radiator by the ceramic coating film 25a and irradiates the stock solution A in the tray 25 with far-infrared rays. Therefore, the stock solution A in the tray 25 can be concentrated more efficiently. In this configuration example, the parts not shown in FIG. 2 have the same configuration as the first configuration example, and are not shown for the sake of simplicity of the drawing.

FIG. 4 shows a third configuration example of the far-infrared heating type vacuum concentration device. In this figure, the same components as those of the first configuration example are designated by the same reference numerals. In this configuration example, a temperature control device 32 that controls the heat load of the far infrared radiator 30 by detecting the liquid temperature of the stock solution A supplied into the concentrating tank 11 by a sensor 33 provided in the middle of the circulating liquid pipe 28, for example.
Are connected to the far-infrared radiator 30 and are provided. In this configuration example, the parts not shown in FIG. 4 have the same configuration as the first configuration example, and are not shown for the sake of simplicity of the drawing. Even with this configuration example, the first
The same effect as that of the configuration example can be obtained.

Referring again to FIG. 1, the concentrated liquid or slurry stock solution A is supplied into the ice maker 40 by the concentrate supply pump 41. The ice making machine 40 has the ability to freeze-make the liquid or slurry stock solution A at a temperature of, for example, -40 ° C to -10 ° C. The liquid or slurry stock solution A is frozen and made into ice by the ice making machine 40 to form a granular material B to be dried.

Next, the structure of the vacuum freeze-drying apparatus 50 shown in FIG. 1 will be described.

The vacuum freeze-drying device 50 is equipped with a vacuum tank 51.
A cold trap 53 is connected to the cold trap 53 via an exhaust valve 52. In the cold trap 53, a condensation coil 55 cooled by the refrigerant from the refrigerator 54 is arranged. The refrigerator 54 changes the surface temperature of the coagulating coil 55 from, for example, -50 ° C to -30
It has the ability to maintain a temperature of ℃. Coagulating coil 55
Collects the steam generated in the vacuum chamber 51 by condensing it.

Although the number of cold traps 53 is one in the illustrated configuration example, 2
Alternatively, the operation may be performed alternately by switching to a predetermined period. Further, although the cold trap 53 is provided outside the vacuum chamber 51 in the illustrated configuration example, the cold trap 53 may be provided directly inside the vacuum chamber 51.

In the illustrated configuration example, vacuum piping is provided in the cold trap 53.
A vacuum exhaust device 57 such as a vacuum pump is connected via 56. The vacuum evacuation device 57 has the ability to maintain the degree of vacuum inside the vacuum chamber 51 at, for example, 2 to 0.1 Torr.

The vacuum freeze-drying apparatus 50 is provided with a material-to-be-dried supplying means for supplying the frozen granular material B to be dried into the vacuum tank 51. In the illustrated configuration example, the material-to-be-dried supply unit includes an intermittent supply device 58 that supplies the frozen granular material B to the vacuum tank 51 by a predetermined amount, and the intermittent supply device 58 extends in the vertical direction. Granular material-to-be-dried supply pipe 59 opening to the upper part in the vacuum tank 51, granular material-to-be-dried storage chamber 60 provided in the middle of the granular material-to-be-dried supply pipe 59, and granular material-to-be-dried storage chamber 60 It is composed of a pair of on-off valves 61 and 62 provided on the inlet side and the outlet side of 60.
0 is connected to the granular dried material storage chamber 60 via the inlet side opening / closing valve 61.

In this configuration example, the inlet-side opening / closing valve 61 is opened in a state where the outlet-side opening / closing valve 62 is closed, so that the granular dried material B frozen and made in the ice making machine 40 is stored in the chamber 60 at one end. After that, the opening / closing valve 61 on the inlet side is closed and the opening / closing valve on the outlet side is closed.
By opening 62, the frozen particulate matter B to be dried in the chamber 60 can be supplied into the vacuum chamber 51 without significantly lowering the degree of vacuum in the vacuum chamber 51.

The vacuum tank 51 is provided with a conveyor 63 for transferring the frozen granular material B to be supplied into the vacuum tank 51 continuously or intermittently. In the illustrated configuration example, three conveyors 63 are arranged in three stages in the vertical direction, the transfer directions of the conveyors 63 are alternately reversed, and the granular material B discharged from the upper conveyor 63 is sequentially arranged. It is supplied onto the lower conveyor 63.

As the conveyor 63, a belt conveyor, a vibration conveyor,
An apron conveyor, a net conveyor, a steel belt conveyor, etc. can be used, and they can be used in an appropriate combination. The number of stages of the conveyor 63 can be appropriately selected according to the amount of the granular material B to be processed B, the water content, and the like.

In the vacuum chamber 51, a plurality of far infrared ray irradiating means for irradiating the frozen granular material B supplied into the vacuum chamber 51 with far infrared rays is provided. The far infrared ray irradiating means includes a far infrared ray radiator 64, and a far infrared ray reflector 65 for reflecting a part of the far infrared ray emitted from the far infrared ray radiator 64 toward the granular material B to be dried on the conveyor 63. In the illustrated configuration example, a plurality of rod-shaped far-infrared radiators 64 and reflectors 65 are arranged above the conveyor 63 at each stage. The far-infrared radiator 64 may have a rod shape, a plate shape, a lamp shape, or a combination thereof.

Although not shown in detail, the far-infrared radiator 64 has a ceramic outer shell containing a heat source inside, or a metal outer shell containing a heat source inside. And a ceramic spray coating film provided on the outer surface thereof. Then, the ceramic is an oxide of any one or more of aluminum, magnesium, chromium, silicon, zirconium, beryllium, lithium, titanium, vanadium, iron, cobalt, nickel, antimony and tin. Is desirable. Further, hot water, heating oil, heating steam, combustion gas, or the like may be used as the heating source of the far-infrared radiator 64, that is, the primary heating element, but it is most preferable to use an electric heater.

The vacuum tank 51 further intermittently discharges the crusher 66 for finely crushing the granular dry matter C discharged from the conveyor 63 at the lowermost stage and the crushed granular dry matter C to the outside of the vacuum tank 51. A discharge means having an intermittent discharge device 67 for is installed, and the intermittent discharge device 67 is a granular dry matter discharge pipe 69 extending downward from the crusher 66 and connected to the product storage tank 68, and the granular particles. It is composed of a granular dry matter storage chamber 70 provided in the middle of the dried matter discharge pipe 69, and a pair of opening / closing valves 71, 72 provided on the inlet side and the outlet side of the granular dry matter storage chamber 70.

The on-off valves 71 and 72 are alternately opened and closed, and the on-off valve 71 on the inlet side is opened while the on-off valve 72 on the outlet side is closed.
The granular dry material C finely pulverized by is supplied into the chamber 70 without greatly reducing the degree of vacuum in the vacuum tank 51, and then the opening / closing valve 71 on the inlet side is closed and the opening / closing valve 72 on the outlet side is closed. By opening, the granular or powdery dried material C in the chamber 70 is discharged into the product storage tank 68.

In the illustrated configuration example, the vacuum freeze-drying apparatus 50 is a temperature sensor 73 that detects the surface temperature of the far infrared radiator 64, and a temperature control that controls the thermal load of the far infrared radiator 64 according to the output of the temperature sensor 73. And a device 74. Far infrared radiator
If the 64 heating source is an electric heater, the controller 74 is configured to control the current supplied to the electric heater.
The operating temperature range of the far-infrared radiator 64 is usually 20 to 600 ° C., but it is in a dry state (constant rate drying period) according to the physical properties, shape, etc. of the material to be dried B, and the drying time on the conveyor 63. It is desirable that the far-infrared radiator 64 be divided into several sections according to the transition of the (decreasing rate dry period) and controlled at appropriate temperatures. Here, the far infrared radiator 64 is a conveyor.
It is divided into three sections according to the number of stages of 63, the temperature sensor 73 is arranged in the vicinity of the far-infrared radiator 64 in each section, and the temperature control device 74 is respectively arranged based on the detection signal of each temperature sensor 73. The far infrared radiator 64 of each section is configured to control the heat load. Three
The temperature of the far-infrared radiator 64 of one section is controlled to, for example, 300 ° C in the uppermost stage, 200 ° C in the second stage, and 100 ° C in the third stage. When controlling the heat load of the far-infrared radiator 64 for each section, the control becomes easy if the primary heating element of the far-infrared radiator 64 is an electric heater.

In the configuration example of the vacuum freeze-drying apparatus 50 shown in FIG. 1, when vacuum freeze-drying the granular dried material B in the frozen state, first, the condensation coil 55 of the cold trap 53 is set to the refrigerator.
By operating 54, the temperature is maintained at a low temperature of, for example, −40 ° C., and by operating the vacuum evacuation device 57, the inside of the vacuum chamber 51 is maintained at a vacuum degree of, for example, 0.77 Torr. Next, the conveyor 63 is operated to supply the frozen granular material B to be dried from the inside of the chamber 60 onto the conveyor 63 at the uppermost stage. In this case, it is preferable to adjust the accumulated thickness of the granular material B to be dried on the conveyor 63 to an optimum value.

The particle size of the frozen granular material to be dried B generated by the ice maker 40 is usually 0.5 mm or more, but if the particle size is 20 mm or more, far infrared rays will not easily penetrate into the material to be dried B, and It becomes difficult for sublimation of water. Therefore, unevenness in drying is likely to occur. Further, the ratio of the surface area (sublimation area) to the deposition of the material to be dried B is also limited, and it takes time to dry.
Therefore, it is preferable that the particle size of the granular material B to be dried is within the range of 0.5 to 20 mm.

On the other hand, the granular material B to be dried having a particle diameter within the above range is conveyed by the conveyor 63.
When deposited on top, the far infrared transmission capacity is limited, so experiments have shown that when the deposition thickness is 40 mm or more, the temperature gradient between the surface and the deep portion of the deposition layer increases. Therefore, if the temperature of the far-infrared radiator 64 is increased in order to accelerate the sublimation of water in the deep granular material B to be dried, excessive heat is applied to the already-dried portion of the surface layer, which causes deterioration of the components. . Moreover, the temperature gradient partially melts the ice, causing the components to melt. Thus, the deposition thickness
If it exceeds 40 mm, the quality of the product will deteriorate and unevenness will occur. On the other hand, if the deposition thickness of the granular material to be dried B on the conveyor 63 is 2 mm or less, it becomes difficult to adjust the thickness in relation to the particle size of the material to be dried B, and the deposition thickness becomes uneven. There is fear.

From the above, it is desirable to adjust the deposition thickness of the granular material to be dried B on the conveyor 63 within the range of 2 to 40 mm.

The frozen granular dried material B accumulated on the conveyor 63 is irradiated with far infrared rays emitted from the far infrared radiator 64 while being conveyed by the conveyor 63. Far infrared radiator 64
May be sequentially heated according to the moving speed of the granular material B to be dried on the conveyor 63. Since the far infrared rays emitted from the far infrared radiator 64 are in good agreement with the infrared absorption characteristics of moisture, the granular material to be dried B is irradiated by the far infrared rays.
The energy supply is efficiently performed to efficiently sublimate the water in the frozen granular material B to be dried. The moisture removed from the granular material to be dried B is condensed and collected by the condensation coil 55. Due to the sublimation of water, the granular material B is conveyed to the conveyor 63.
It becomes the granular dry matter C above, falls from the lowermost conveyor 63 into the crusher 66, is crushed, and is successively accumulated in the product storage tank 68 via the chamber 70 by the operation of the opening / closing valves 71 and 72.

According to the working conditions of the concentrating device 10, the ice maker 40, and the vacuum freeze-drying device 50 illustrated above, for example, a dilute aqueous solution containing various amino acids (amino concentration 3 wt%) is concentrated by the concentrating device 10 at 10 vol% (amino acid concentration 30 wt%. ) And freeze-dried the concentrated solution in a granular form with an ice-making machine 40 to be dried B
And, when the far infrared rays were radiated using the rod-shaped far infrared radiator 64 in the vacuum freeze-drying apparatus 50, the heat receiving area was 9.7 m.
^{With 2} , it was possible to process about 10 kg / hr. At this time, the temperature of the material to be dried B is about −20 ° C. in the constant rate drying period and 20 ° C. in the taking out.
The temperature reached -40 ° C, and a powdery dry product (amino acid powder) with good quality was obtained. It was confirmed that the obtained powder product, that is, the amino acid powder, is stable and can be stored for a long period of time, and that it is restored to its original physical properties when redissolved in water.

In the configuration example shown in FIG. 1, the concentration step, the frozen ice making step, and the vacuum freeze-drying step can be performed continuously, but each step can also be separated and processed. For example, when the concentrated raw materials are frozen and made into ice by a separate ice making machine to form a granular material to be dried, the ice making machine 40 shown in FIG.
Can be used as a freezing tank for the granular material B to be dried.

FIG. 5 shows another structural example of the vacuum freeze-drying apparatus 50. In the figure, the same reference numerals are attached to the same components as those in the above-described configuration example. In this configuration example, the vacuum chamber 51 has a chamber body 51a having an opening at one end, and the chamber body 5
It has a door 51b for opening and closing the opening of 1a. A refrigeration fan 75 and a condensation coil / refrigeration coil 76 are provided at the rear of the tank main body 51a. The refrigerator 54, the exhaust valve 52, the vacuum pipe 56, the vacuum exhaust device 57, and the like perform the same operations as in the configuration example shown in FIG.

Inside the tank body 51a of the vacuum tank 51, a carry-in jig 77 is provided as a material to be dried supplying means. The carry-in jig 77 can be carried into the tank main body 51a through the opening of the tank main body 51a.
It can also be carried out. Wheels 78 are provided below the carry-in jig 77 to facilitate the carry-in and carry-out of the carry-in jig 77.

The carry-in jig 77 is provided with a plurality of dish-shaped trays 79 that carry the frozen granular material B to be dried. A plate-shaped far-infrared radiator 64 is arranged above each tray 79, and a loading jig is provided.
It is fixed at 77. Shape, material of the far infrared radiator 64,
The number, operating temperature range and the like can be the same as those in the configuration example shown in FIG. In the configuration example of FIG. 5, the trays are arranged vertically in two stages, but the number of stages is not limited to this.

The vacuum freeze-drying apparatus 50 shown in FIG. 5 detects the surface temperature of the far-infrared radiator 64 and a weighing machine 80 which measures the weight change of the granular material B on the tray 79 due to drying and converts it into an output signal. Temperature sensor 73, and a temperature control device 81 for controlling the heat load of the far-infrared irradiation body 64 to an optimum value according to the output signals of the weighing machine 80 and the temperature sensor 73.

In the vacuum freeze-drying apparatus 50 shown in FIG.
As for the supply form, the granules that have been pre-frozen in the outside may be filled on the tray 79 and supplied into the vacuum chamber 51, or the unfrozen granular material B to be dried may be filled on the tray 79. After being supplied to the vacuum chamber 51, the vacuum chamber 51 may be pre-frozen or self-frozen. The condensation coil and freezing coil 76 is
It is used as a condensation coil during self-freezing and vacuum freeze-drying, and as a freezing coil during preliminary freezing.

When performing vacuum freeze-drying of the granular material to be dried B previously frozen outside by using the vacuum freeze-drying apparatus 50 shown in FIG. 5, first, the granular material to be dried B in a frozen state is preferably placed on the tray 79. By loading the loading jig 77 into the tank body 51a of the vacuum tank 51 by depositing it in a thickness within the range of 2 to 40 mm, closing the door 51b and setting the condensation coil / freezing coil 76 by the operation of the refrigerator 54, for example, − The vacuum chamber 51 is maintained at a low temperature of 40 ° C., and the inside of the vacuum chamber 51 is maintained at a vacuum degree of 0.77 Torr by the operation of the vacuum exhaust device 57.

Next, the far-infrared radiator 64 is heated to generate far-infrared radiator.
Far-infrared rays are irradiated from 64 to the granular material B to be dried on the tray 79. The temperature of the far-infrared radiator 64 is sequentially controlled based on the output signals of the weighing machine 80 and the temperature sensor 73, such as 150 ° C. and 100 ° C., in accordance with the dry state of the material to be dried B. Far-infrared ray suitable for sublimation of water is irradiated from the far-infrared ray radiator 64 to the material to be dried B and is dried. The water removed from the material to be dried B is condensed and collected by the coil 76.

It has been confirmed that, under the working conditions exemplified above, a dried product substantially similar to the vacuum freeze-drying apparatus shown in FIG. 1 can be obtained.

〔The invention's effect〕

As is clear from the above description, according to the present invention, the aqueous solution raw material is concentrated by far-infrared heating under reduced pressure, then frozen and ice-formed into granules, and freeze-dried by far-infrared heating under vacuum. It becomes possible to efficiently obtain a dried product. Moreover, since the material to be dried in the frozen state is granular, uneven drying is less likely to occur, and a high-quality dried product can be obtained.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram showing one configuration example of a concentrating device, an ice making machine and a vacuum freeze-drying device for carrying out the method of the present invention, and FIG. 2 is a schematic configuration of a main part showing another configuration example of the concentrating device. Fig. 3, Fig. 3 is an enlarged cross-sectional view of the tray in the concentrating device shown in Fig. 2, Fig. 4 is a schematic configuration diagram of a main part showing still another configuration example of the concentrating device, and Fig. 5 is a vacuum freeze-drying device. It is a schematic block diagram which shows another structural example. In the figure, 10 is a concentrating device, 11 is a concentrating tank, 30 is a far-infrared radiator, 40 is an ice making machine, 50 is a vacuum freeze-drying device, 51 is a vacuum layer, 51a is a tank body, 51b is a door, 53 is a cold trap. , 57
Is an evacuation device, 58 is an intermittent supply device, 63 is a conveyor, and 64 is
Is a far-infrared radiator, 65 is a reflector, 66 is a crusher, 67 is an intermittent discharge device, 73 is a temperature sensor, 74 and 81 are temperature control devices, 76
Is a condensation coil and freezing coil, 77 is a carry-in jig, 79 is a tray, 80 is a weighing machine, A is a stock solution, B is a granular material to be dried, and C is a granular dried material.

Claims (18)

[Claims] 1. A step of irradiating an aqueous solution raw material with far-infrared rays in a depressurized concentrating tank to concentrate the aqueous solution raw material, and a step of producing water to freeze the concentrated raw material to produce a frozen material to be dried. And a step of irradiating the granular dried material in a frozen state with far-infrared rays in a vacuum chamber to sublimate water in the dried material to dry the granular dried material. 2. The method for producing a granular dried product according to claim 1, wherein the raw material for the aqueous solution is made to flow down along a multi-stage tray in the concentrating tank and is irradiated with far infrared rays. 3. A vacuum tank for drying the granular material to be dried, a vacuum evacuation means connected to the vacuum tank for evacuating the inside of the vacuum tank to a vacuum, and for condensing and collecting water in the exhaust gas. A cold trap device, a material to be dried supply means for supplying a frozen granular material to be dried into a vacuum tank, and a far-infrared irradiation for irradiating the frozen granular material to be dried in the vacuum apparatus with far infrared rays. A vacuum freeze-drying device comprising a means and a discharging means for discharging the dried granular material from the vacuum tank. 4. The far-infrared irradiation means comprises a far-infrared radiator, and the far-infrared radiator has a rod shape, a plate shape, a lamp shape, or a combination thereof. The vacuum freeze-drying device according to. 5. The far-infrared radiator has an outer shell containing a heating source therein, and the outer shell is made of ceramics. The vacuum freeze-drying device described. 6. A far infrared ray radiator having a metallic outer shell containing a heating source therein and a ceramic sprayed coating film provided on the outer surface thereof. The vacuum freeze-drying device according to item 4. 7. The ceramic comprises an oxide of any one or more of aluminum, magnesium, chromium, silicon, zirconium, beryllium, lithium, titanium, vanadium, iron, cobalt, nickel, antimony and tin. The vacuum freeze-drying device according to claim 5 or 6, characterized in that. 8. The vacuum freeze-drying apparatus according to claim 5, wherein the far-infrared radiator is heated by an electric heater. 9. The far infrared ray irradiating means comprises a far infrared ray reflector for reflecting a part of the far infrared ray emitted from the far infrared ray radiator toward the granular material to be dried. The vacuum freeze-drying device according to claim 4. 10. The article-to-be-dried supply means is provided with an intermittent supply device for supplying a predetermined amount of frozen granular matter to be dried into the vacuum tank, and the granular material supplied into the vacuum tank is provided in the vacuum tank. The vacuum freeze according to claim 3, further comprising a conveyor for transferring the material to be dried continuously or intermittently, and the far-infrared irradiation means is disposed above the conveyor. Drying device. 11. The vacuum freeze-drying device according to claim 10, wherein the conveyor comprises a belt conveyor, a vibration conveyor, an apron conveyor, a net conveyor, a steel belt conveyor or a combination thereof. 12. A plurality of conveyors are vertically arranged in multiple stages so that the transfer directions of the conveyors are alternately opposite, and the granular material to be dried discharged from the upper conveyor is sequentially transferred to the lower conveyor. The far-infrared irradiation means is arranged above the conveyor of each stage, the vacuum freeze-drying according to claim 10 or 11 characterized in that apparatus. 13. An intermittent supply device is provided with a granular material-to-be-dried material supply pipe which extends in the vertical direction and opens at an upper part of a vacuum chamber, and a granular material-to-be-dried material provided in the middle of the granular material-to-be-dried material supply piping. 11. The vacuum freeze-drying device according to claim 10, comprising a storage chamber and a pair of open / close valves provided on the inlet side and the outlet side of the granular dried storage chamber. 14. The discharging means comprises a crusher for crushing the granular dry material, and an intermittent discharging device for intermittently discharging the granular dry material crushed by the crusher to the outside of the vacuum chamber. The vacuum freeze-drying device according to claim 3, wherein the vacuum freeze-drying device is provided. 15. A granular dry matter discharge pipe having an intermittent discharge device extending downward from the crusher, a granular dry matter storage chamber provided in the middle of the granular dry matter discharge pipe, and a granular dry matter storage chamber. Claim 14 characterized in that it comprises a pair of on-off valves provided on the inlet side and the outlet side.
The vacuum freeze-drying device according to the item. 16. The vacuum freeze according to claim 3, further comprising a temperature control device for detecting the surface temperature of the far-infrared irradiation means and controlling the heat load of the far-infrared irradiation means. Drying device. 17. A vacuum tank comprising a tank body having an opening at one end and a door for opening and closing the opening of the tank body, wherein the material to be dried supply means passes through the opening of the tank body. Is equipped with a carry-in jig that can be carried into the tank main body, and the carry-in jig is provided with a tray for carrying the frozen granular material to be dried, and the far-infrared irradiation means is arranged above the tray. The vacuum freeze-drying apparatus according to claim 3, wherein the vacuum freeze-drying apparatus is attached to a carry-in jig. 18. A measuring means for measuring a weight change of a granular material to be dried on a tray and converting it into an output signal, a temperature sensor for detecting a surface temperature of far-infrared irradiation means, the measuring means and temperature. 18. The vacuum freeze-drying device according to claim 17, further comprising: a temperature control device that controls the heat load of the far-infrared irradiation means according to the output signal of the sensor.