JPH0478909B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that an unfrozen material to be dried (liquid or plate-like) is placed in a freeze-drying device or a drying container such as a tray used for freeze-drying, frozen, and then dried. Thereafter, the present invention relates to a freeze-drying method in which a dried material is removed from the apparatus or the container to produce a product, and a vacuum freeze-drying apparatus used to carry out the method.

As a means of freeze-drying the material to be dried into a dry product using a method different from that described above, the material to be dried is prepared in advance into a frozen body that has been adjusted to the desired shape, and then it is placed on a sufficiently cooled tray or the like for drying. There is a method of filling a container and placing the entire container into the drying chamber of a vacuum freeze-drying device for drying.Alternatively, there is a method of filling unfrozen materials into a sealable container and loading the container into the drying chamber of a vacuum freeze-drying device. After freezing and drying, there is a method of sealing the container itself and taking it out as a product.
In the former method, adhesion between the frozen body and the drying container can be avoided, so that the dried product can be easily recovered from the drying container, and in the latter method, there is no need to collect the product from the drying container.

However, as in the method targeted by the present invention, unfrozen liquid or flat material is directly stored on a freezing/heating surface installed in the drying chamber of a vacuum freeze-drying device or in a drying container charged into the drying chamber. In the case of freezing and subsequent drying, unless special processing is applied to the freezing/heating surface or the inner surface of the drying container, there will be no space between the dried product and the freezing/heating surface or the inner surface of the drying container due to freezing. causes adhesion,
When recovering dried product from a freezing/heating surface or a drying container, gently sliding the dry product against the freezing/heating surface or simply inverting the drying container will prevent some or residue of the dried product from remaining on the surface. Put it away. The complexity of collection operations, product loss, and the need to clean the freezing/heating surface or drying container each time.
Such difficulties cannot be avoided.

For this reason, it is not practical to directly freeze an unfrozen liquid or a plate-shaped material onto the freezing/heating surface of a vacuum freeze-drying device, and only the method of freezing the material by placing it in a container such as a tray is used. Although the above-mentioned disadvantages still exist when using a container, this is more bearable than contaminating the vacuum freeze-drying apparatus itself. Despite the above-mentioned difficulties,
After placing it in a dry container such as a tray in an unfrozen state,
The widely adopted method is to place the entire container into the drying chamber of a vacuum freeze-drying device, freeze it, continue drying, and recover the dried product from the drying container.
This is because the process is simple and efficient.

The present invention has been made in order to solve the above-mentioned difficulties, and it is possible to directly dry an unfrozen liquid or flat material to be dried on a freezing/heating surface installed in the drying chamber of a vacuum freeze-drying apparatus. While supplying the material to the inner surface of the drying container charged into the drying chamber and then freezing it for lyophilization, the dried material may adhere to the freezing/heating surface or the inner surface of the drying container. The purpose of the present invention is to provide a new means for cleanly peeling off these surfaces with a small amount of force without causing any damage.

In the present invention, as a means to achieve this objective, water is poured onto the freezing surface of the freezing and heating surface installed inside the drying chamber of the vacuum freeze-drying device, and the freezing surface is cooled to below 0°C. Then, an ice film is formed on the frozen surface, and while the frozen surface is kept at a sufficiently low temperature of 0° C. or less, a liquid or plate-shaped material to be dried is supplied onto the ice film. A freeze-drying method characterized by freezing a drying material on the ice film, then evacuating the drying chamber, and drying the frozen layer of the material to be dried and the ice film under a vacuum, and vacuum freeze-drying. Water is poured onto the inner surface of a container for the material to be dried, which is placed in the drying chamber of the apparatus, and the container is cooled to below 0°C to form an ice film on the inner surface of the container, and then the container is cooled sufficiently below 0°C. supplying a liquid or flat material to be dried onto the ice film while maintaining the temperature at a relatively low temperature to freeze the material to be dried on the ice film, and then evacuating the drying chamber;
The present invention proposes a freeze-drying method in which a frozen layer and an ice film of the material to be dried are dried under a vacuum condition, and an apparatus for carrying out this method is a drying method in which the inside is maintained at a normal degree of vacuum. A freezing/heating surface configured as a single or multi-stage horizontal shelf in the drying chamber, a material to be dried fixedly or movably arranged on the shelf, and a material to be dried arranged on the shelf. Vacuum freeze drying characterized by having a water injection mechanism that sprays water almost evenly onto the shelf surface surrounded by a frame and the contact area between the frame and the shelf surface, and a door surface located at the front of the shelf. an apparatus, a drying chamber whose interior is maintained at a normal degree of vacuum, and within the drying chamber one or more upright surfaces, such as an upright cylindrical surface (inner cylindrical surface or outer cylindrical surface) or an upright planar surface; a freezing/heating surface, a supply/drainage mechanism that supplies and discharges water almost evenly to the freezing/heating surface, and a liquid supply/drainage mechanism that supplies and discharges liquid material to be dried into the space above the freezing/heating surface. and a door surface located at the lower end surface of the drying chamber.

According to the means of the present invention, the material to be dried is placed on a freezing surface constituted by a freezing/heating surface installed in the drying chamber of a vacuum freeze-drying apparatus or an inner surface of a drying container placed in the drying chamber. , a frozen layer is created between the ice layers that have been pre-frozen there. During the drying process, this ice film sublimates and disappears together with the sublimation of water vapor from the material to be dried, so the material to be dried becomes dry and this ice film disappears. Since it comes into contact with the frozen surface through a thin film-like interval formed by The dried product can be recovered by force, and no trace of the dried product will remain on the frozen surface. And from this, the following advantages arise.

1) Drying containers such as trays are not required unless there are special restrictions, and the material to be dried (liquid or flat plate) is supplied directly to the freezing and heating surface of the drying equipment, and after freezing and drying, it can be collected directly from the equipment. (Transportation of drying containers, taking them in and out of the drying room,
2) Since the material to be dried is frozen by direct contact with the freezing/heating surface via an ice film, the drying container and the freezing/heating surface can be omitted. This eliminates contact heat transfer, which differs from drying container to drying container and is uneven depending on where the drying container is placed, and enables homogeneous and rapid (or well-controlled freeze-drying) pre-freezing.

(Note) When the temperature of the freezing/heating surface is controlled by circulating a heat medium fluid, the heat transfer coefficient between the heat medium fluid and the freezing/heating surface is 700 to 600 (kcal/m ² h℃,
(Units are omitted below), whereas the above-mentioned contact heat transfer is about 70 to 60 on average, so the overall heat transfer coefficient for both is dominated by the degree of contact, which varies widely, and is about 60 on average. On the other hand, ice film heat transfer is 4000 when the ice film thickness is 0.5 mm.
The overall heat transfer is not affected much by the resistance of the ice film, and even if the thickness of the ice film is uneven, the heat transfer with excellent uniformity between the heating medium fluid and the freezing/heating surface is dominant. Therefore, the average freezing speed can be several times that of the tray method.

3) Since the material to be dried is frozen on the ice film, the material to be dried begins to freeze all at once on the ice film at the freezing point without supercooling, and this is combined with the effect of 1) above. , it begins to freeze while growing uniform needle-shaped ice crystals that stand upright on the frozen surface. This ice crystal arrangement favors both heat conduction and water vapor transmission, promoting even drying.
(A solution without ice does not start freezing at the freezing point, and sudden freezing and recrystallization after supercooling creates a layer of ice crystals with erect granules, which is disadvantageous for uniform drying.) 4 ) Even if the ice film is a thin film of about 0.5 mm, it is much larger than the pore diameter of the dry porous material, which is 0.1 to 0.01 mm, so it sublimates and disappears through the edges and cracks in the middle of the drying process of the material to be dried. This makes it possible for water vapor to escape from both the front and back surfaces of the material to be dried, making drying advantageous and preventing melting of the adhered portion.

5) If a drying container is required due to special constraints (factory, equipment layout, etc.), the advantages of 1) and 2) above will disappear, but an ice film will form on the inside of the drying container. By this, advantages 3) and 4)
It is easy to recover the dried product from the drying container, and it is not necessary to wash the drying container since it is carried out after each drying process.

In addition, in the method of the present invention, in addition to the material to be dried, the loads of ice film formation, sublimation, condensation, and deicing are added. However, while the moisture in the material to be dried per unit area is usually about 10Kg (H ₂ O)/m ² or more, the moisture in the ice film is about 0.5Kg/m ² (5% of the true load). 10% or less), the energy loss due to this load is much smaller than the overall refrigeration energy saving effect due to the several-fold increase in the heat transfer coefficient mentioned in Advantage 2).

The common advantages of the present invention have been comprehensively described above.
The freeze-drying method according to the present invention can be implemented in the most suitable method and apparatus depending on the nature, scale, etc. of the materials to be handled. Next, the second and third embodiments will be explained.

The first is when it is used in a shelf format. This embodiment can be applied to existing vacuum freeze drying equipment by adding or modifying certain equipment.

FIG. 1 is a side sectional view of a main part of an apparatus according to an embodiment of the present invention applied to this tray-type vacuum freeze-drying apparatus, and FIG. 2 is a perspective view of the main part.

In the figure, 4 is a drying chamber of a normal vacuum freeze-drying device, 1... is a freezing and heating surface installed in the form of shelves in the drying chamber 4, and the drying chamber 4 has an open opening on the front side. The opening/closing door provided at 4a is omitted in the drawing, and each shelf 1a of the freezing/heating surface 1...
Although not clearly shown in the drawing, the uppermost shelf 1a is connected to the uppermost shelf 1a, which is connected to a drive unit 6 that moves up and down, through a linkage mechanism that expands and contracts, and the drive unit 6 reaches the stroke end on the upward side. By being pulled up, the shelves are lined up in a tiered manner with a constant interval between them, and when the drive unit 6 is lowered, the shelves are stacked one after another starting from the lowest shelf 1a. Each shelf 1a is equipped with a conduit through which a cooling medium and a heating medium flow.

Reference numeral 2 denotes a frame for the material to be dried, which is placed closely on the freezing/heating surface 1 formed by the upper surface of each shelf 1a except for the topmost shelf 1a, and is a simple rectangular frame.
Alternatively, it is formed in a lattice shape, and in this embodiment, it can be slid by a low-friction rail 7 toward the opening/closing door of the drying chamber 4.

3 is installed in the drying chamber 4 so that when the frame 2... is on the freezing/heating surface 1..., water is almost evenly distributed over the frame 2 and the shelf surface surrounded by the frame 2. In this embodiment, the water injection mechanism is comprised of a large number of spray nozzles 3a, which are attached to both sides of the shelves 1a. In this embodiment, the water injection mechanism 3 is provided at one location on each side of the drying chamber 4, and each shelf 1a is connected to a drive unit 6.
By moving all the shelves 1a... from the top to position A where they can receive water spray from the spray nozzles 3a...
water supply is now available.
In order to raise and lower the shelves 1a..., the materials to be dried are loaded and taken out from the multi-stage shelves 1a... at a certain position A.
Although it is advantageous that it can be carried out at shelf 1a...
may be fixed, the water injection mechanism 3 may be movable up and down, and the position in and out of the material may be changed for each shelf 1a.

Further, the frame 2 may be fixed to the shelves 1a, or the shelves 1a may be tilted to allow the dried material to slide out when taken out.

The embodiment apparatus configured as described above is operated according to the following procedure.

Place the shelf 1a on which the frame 2 is placed at a predetermined position A.
The shelf 1a is kept at 0°C or below, and the valve of the water injection mechanism 3 is opened to pour a predetermined amount of water onto the freezing/heating surface 1 of the shelf 1a surrounded by the frame 2, the lower end of the frame 2, and its freezing/heating surface. When sprayed on the contact area with 1,
The sprayed water freezes and forms an ice film. While continuing to keep shelf 1a at a sufficiently low temperature below 0°C,
When the material to be dried is liquid, the liquid material is poured into the frame 2 using a metering syringe. In this case, it is desirable for the liquid material to be cooled in advance to near its freezing point (lowest temperature at which it will not freeze), both for quality preservation and for protection of the ice film. However, for example, even if the liquid is at room temperature, there will be no problem as long as the ice temperature and the shelf surface are sufficiently deeply cooled. If the injection rate is not extremely slow, the liquid material will flow horizontally into frame 2.
Expand within. If the material to be dried is a flat solid material such as sliced meat, it is arranged evenly and horizontally within the frame 2. Due to the presence of the ice film and uniform heat transfer, supercooling does not occur, and uniform upright needle-shaped ice crystals grow within the material to be dried and the material freezes. If the shelf temperature during this period is accurately controlled, the growth rate of ice crystals can be controlled because there is no contact thermal resistance, and therefore the thickness of the ice crystals can be controlled. After freezing, the interior of the drying chamber 4 is evacuated, and while maintaining the necessary vacuum, the temperature of the shelf 1a is controlled and drying begins. Initially, the material to be dried is in close contact with the upper surface of the shelf 1a via the ice film, so the shelf temperature should be kept low, and sufficient heat can be supplied at the low shelf temperature. However, as the drying progresses, usually 50 to 60% (depending on the properties of the material and drying conditions) becomes dry.
Water vapor escapes from cracks that normally occur during freezing, and the ice film disappears by sublimation, and sublimes from the bottom surface of the material to be dried, making drying easier. From around this time, the shelf temperature will increase. After the drying is completed, the vacuum is broken, the door of the drying chamber 4 is opened, the product receivers 5 are applied to each shelf 1a, and the frame 2 is pulled toward the front. The dried product 8 often has cracks formed during the freezing and drying process and, due to certain shrinkage, is collected in the product receiver 5 as fragments smaller than the frame 2 dimensions. The frame 2 is returned to the correct position by sliding again, or once recovered outside the drying chamber. In the above embodiments, the formation of an ice film is based on water spraying onto the shelves 1a that have been cooled to below 0°C.
Freezing may be carried out after forming a water film on the freezing/heating surface 1.

Next, FIGS. 3 and 4 show an embodiment of the apparatus having no shelves. This embodiment is an apparatus suitable for use in drying only liquid materials and continuously drying the same material. On the other hand, according to this embodiment, the above-mentioned 1) to 5)
In addition to the above advantages, the following advantages are added.

6) Freeze-drying can be performed in a completely sealed space and line, making it easy to maintain highly hygienic conditions of sterility and no foreign substances.

7) There is no drive unit in the vacuum chamber, and everything from supplying materials to collecting products can be automated by simply starting and stopping the circulation pump in the liquid transport line, opening and closing valves, and opening and closing the dry product door.

8) Drying is easier because the surface of the frozen layer of the material to be dried is not covered with a film that is impermeable to water vapor. (Details will be described later) Next, some of the embodiment devices of this form will be explained based on the drawings.

FIG. 3 shows a first embodiment of this configuration. In the figure, a is a drying chamber of a vacuum freeze-drying apparatus, and a single or plural cylinders b are arranged upright in the drying chamber a, and the inner wall surface or outer wall surface of the cylinder b can be evacuated. The cylindrical wall can be cooled and heated from the opposite side. In this example, the inner sides 11 of the plurality of upright cylinders b can be evacuated, and the antifreeze heat medium fluid is circulated around the outer sides 12 of the cylinders b. Therefore, in this example, the upright cylinder b...
Each inner wall surface becomes a freezing/heating surface 1.

Next, FIG. 4 shows a second embodiment of this form, in which a plurality of upright cylinders b... are formed into double pipes, in which an antifreeze heat medium fluid is circulated inside 11, The structure is such that the outside 12 of the cylinder group can be evacuated. Therefore, in this example, the outer wall surface of the cylinder b becomes the freezing and heating surface 1.

FIG. 3a is the upper half of a plan view with the upper door 17 omitted, and FIG. 3b is a side view taken along the line SS.

In the embodiment shown in FIG. 3, the upper space of the cylinder b... is connected to a trap chamber 21 of a vacuum freeze-drying apparatus, and a vacuum pump (omitted) is connected via a conduit 22 through the trap chamber 21. . Trap room 2
The coil-shaped trap 18 disposed within the
Refrigerant or heating medium circulates (inlet is double arrow,
The outlet (omitted) is provided at a position symmetrical to the inlet in the SS cross section of FIG. 4).

FIG. 4a is a plan view taken along the line CC in FIG. 4b, and FIG. 4b is a side view taken along the line S-S in FIG. 4a.
Also in the embodiment shown in FIG. 4, the upper space communicates with the trap chamber 21, and the trap chamber 21
is connected to a vacuum pump system (omitted) via a conduit 22.

The operation will be explained below with reference to FIG. 3b.

First, a heat medium cooled to below 0°C is circulated between the outer side 12 of the cylinder b group, that is, the cylindrical shell 14, and the cylinder b group (inlets and outlets are shown by half arrows), and the cylinder b group A water supply tank 1 that communicates with it from a water inlet 23 provided in the lower space surface of the shell 14 that houses the
3. Introduce the water in each cylinder b to a level close to the upper end. The water begins to freeze from the inner wall of cylinder b, which has already been cooled to below 0°C. Preferably less than 1 mm,
When ice with a thickness of about 0.5 mm is formed, cylinder b
...The water filled in the group is drained from the drain port 24 (indicated by a white arrow). Subsequently, cylinder b... group is cooled sufficiently deeply, and a liquid material that has been cooled in advance in the liquid supply tank 20 to about the freezing point of the liquid material is poured into it from the liquid supply port that also serves as the water injection port 23. , the cylinders b... are filled to just below the level at which the ice film has already formed. The frozen layer 10 of the liquid material increases uniformly from the interface with the ice film on the inner surface of the wall of the cylinder b toward the central axis of the group of cylinders b. At the desired thickness, that is, the thickness of the frozen layer that leaves an unfrozen part corresponding to the passage necessary for water vapor escape in the center of cylinder b...group, the liquid material discharge pipe that also serves as the drain port 24 is connected to the liquid receiving tank. Collect the liquid material at 30 minutes. In the example of FIG. 3, the water inlet 23 and the liquid supply port are shared, and the drain port 24 is shared, but they may be separate ports. Since the interface temperature between the frozen part and the unfrozen part is naturally the freezing point of the liquid material, the temperature of the liquid collected in the liquid receiving tank 30 is at the freezing point temperature as well as the temperature of the liquid in the water supply tank 13. The liquid collected in the liquid receiving tank 30 is pumped up to the liquid receiving tank 20 for the next time, but when many freeze-drying chambers are arranged in parallel, the liquid is pumped up to the liquid receiving tank attached to the next freeze-drying chamber to be operated. The water can be pumped into a single water tank common to multiple freeze-drying chambers.

After closing all the valves (omitted) for the water and liquid piping, the drying chamber a (the inside of cylinder b... group and the space above and below it) is evacuated to the desired vacuum pressure by the vacuum pump system through the trap chamber 21. , the heating medium flowing between the outer periphery of the cylinder b... and the inside of the shell 14 is heated by the circulating heating medium (half arrows indicate entry and exit) to the extent that the material and the ice film do not melt, and freeze-drying proceeds.

In the early stage of drying, the frozen layer 10 adheres to the inner wall of each cylinder b through an ice film, and sublimation proceeds from the axis side of each cylinder b. As a result, the frozen layer 10 transforms into a dry layer from each axis side, but eventually the ice film itself sublimates and disappears, making it free for each cylinder b... Therefore, in order to prevent the material to be dried from falling off from the cylinder b, a support is required at the lower end of each cylinder b. In the example shown in FIG. 3, a wire mesh or a support rod attached to the back side of the lower door 16 of the drying chamber a serves as a support 19 for preventing the dried material from falling.

After the freeze-drying is completed, the pressure in the drying chamber a is restored to 1 atm, and when the lower door 16 is opened downward around the hinge 16a, the dried product, which has become free with respect to each cylinder b due to the disappearance of the ice film, is It freely descends depending on the opening degree of the lower door 16, is guided by the product receiver 25, and falls into the product tank 15 at the lower part. Freeze-dried liquid materials, which are dry products, are brittle and can be damaged by a light impact when dropped.
It is broken into pieces about cm in size, falls into the product tank 15, and is collected. Due to the impact of the fall, the cylindrical dry body was damaged by several centimeters.
When the powder is divided into the following sizes, a small amount of fine powder may be generated and slightly adhere to the sloped surface of the product receiver 25, but the sloped surface of the product receiver 25 will be in contact with both the liquid material to be injected next time and the vacuum. This does not interfere with sanitary conditions as it is a closed space with no heating or humidification. No trace of dried powder that can be detected by naked eye observation can be found on the inner wall of the cylinder b group or on the lower end surface of the heat transfer medium container connecting the cylinder b group and the shell 14.

Needless to say, it is possible to form a frozen layer 10 of liquid material and freeze-dry it without forming an ice film on the cylinder b... group having the shape of FIG. 3 or 4. Even if there is no ice film on some materials, only a small amount of adhesion will peel off, and even if there is adhesion, the adhesion will dissolve into the next low temperature liquid injected without stirring and will not interfere with the material. Although it cannot be said with certainty that there is no material present, in general, without an ice film, a considerable amount of deposits remain, albeit to varying degrees, and simple injection of low-temperature liquid does not dissolve these deposits.

In the above description, the ice film is formed by injecting water into the cylinder b and freezing it, but other methods may be used. That is, in the apparatus of the above-described embodiment, after taking out the dried product, the temperature of the cylinder b... group was maintained slightly higher than 0°C, the drying chamber a was evacuated, and a bottom heater was provided at the bottom of the trap chamber 21. When the water accumulated there is heated, the accumulated water at the bottom evaporates and condenses on each inner wall surface of cylinder b... keep it. Therefore, the temperature of cylinder b... group is rapidly cooled to 0° C. or lower to freeze the condensed film. As the standing water at the bottom of the trap chamber 21, it is possible to use melted water from trap condensed ice during freeze-drying without introducing new water.

In the embodiment shown in FIGS. 3 and 4, a part of the liquid once supplied from the liquid receiving tank 20 into the cylinders b... group is recovered in liquid form and passed to the next time, and further,
Some of it will be passed on from time to time.

Therefore, these examples are not suitable for applications where a certain amount of material is dried in one time and then immediately transferred to another type (in this case, the examples shown in Figures 1 and 2 are suitable). .

However, it is most suitable for applications where certain varieties are dried continuously for a certain period of time. A portion of the prepared liquid material is passed on to the next time, one after another, but the temperature of the liquid during this time is always maintained at the freezing point of the material, and in a closed space, due to the unique features of this embodiment. Generally, these conditions are optimal for preservation. In addition, as shown in the conceptual diagram in Figure 5, the residence time can be reduced by dividing the equipment into several drying chambers instead of concentrating them on one large drying chamber, and transferring the liquid collected in the first liquid receiving tank 30-1 to the next drying chamber. The liquid is sent to the liquid supply tank 20-2 for the drying room. The drying chamber a has N (=6) groups,
If one drying time is H (= 12) hours and X = (52)% of the liquid supplied into the cylinder b is collected in the liquid receiving tank 30, the liquid that stays in the Plato for θ = 12 hours. The percentage of material in the dry product is only X=2%. (When X = 0.6, it is 4.7%.) Using this as a guide, you can make an operation plan and judge whether it is appropriate to use it.

FIG. 5 is an explanatory diagram of a plant in which a plurality of drying chambers are operated continuously at equal time differences, and the flow of materials to be dried is omitted. The numbers 1, 2,...N after the symbols (numbers) already used in Figures 3 and 4 are
Shows the number of drying room a. The stock solution is continuously sent from a common supply source, and a predetermined amount is supplied to the supply tank 20-1.
When the liquid is sent to the liquid supply tank 20-2, the supply is switched to the liquid supply tank 20-2.

From the water supply tank 13, water is sent into the cylinder b of the drying chamber a-1, and after forming an ice film, it is discharged, and the water is sent to the cylinder b of the drying chamber a-1.
1 liquid is sent into the cylinder b... of the drying chamber a-1,
After forming a predetermined frozen layer, the surplus is dropped into the liquid receiving tank 30-1, and the time until the start of drying chamber a-2, that is, the freeze-drying time H (for example, 12), is increased by the number of drying chambers N (for example, 6). The liquid is pumped into the liquid supply tank 20-2 by the pump within hours divided by H/N (for example, 2), and becomes one with the liquid from the supply source 100. This is repeated. Nth liquid receiving tank 30-N
The liquid is pumped into the No. 1 liquid supply tank 20-1. After H (e.g. 12) hours, the dried product is
Product tanks 15-1, 15 at intervals of N (for example, 2 hours)
-2... are collected in order of number. The processing of the products in each product tank 15 can be determined in relation to the subsequent steps.

In FIG. 5, for convenience of explanation of the flow of the stock solution, the liquid supply tanks 20-1 and 2 are provided in each drying chamber a.
0-2,...20-N, and liquid receiving tanks 30-1, 30-
2,...30-N was provided, but depending on the number and arrangement of drying chambers, one common liquid supply tank, one common liquid receiving tank, and one pump each may be provided for all the drying chambers. Alternatively, the number of common tanks may be one for every two or three drying chambers a, and the number of common tanks may be smaller than the number of drying chambers.

In addition, the cylinder b... installed in the drying chamber a is the sixth
As in the embodiments shown in Figures a and 6b, it is formed into a thin flat box-shaped cylinder b';
b'(s) may be arranged upright, with cooling and heating media circulating inside it, and the outer surface configured as a freezing and heating surface 1.
Note that the same reference numerals are given to the constituent members having the same effect, and the explanation thereof will be omitted. The embodiment shown in FIG. 6 is used in the same operating procedure as the embodiments shown in FIGS. 3a-b and 4a-b, and functions in the same manner.

As described above, the most important feature of the embodiments of the present invention shown in FIGS. The process can be carried out within the device, and its operation proceeds with a simple combination of opening and closing automatic valves in the liquid piping system, starting and stopping the liquid pump, and opening and closing the drying chamber door. Other than the valves, pumps, and doors mentioned above, there are no driving parts (rotating parts, sliding parts, etc.) inside, so a high level of sanitary conditions can be maintained.

The above features do not exist in any conventional freeze-drying equipment that has been put to practical use, and by forming a frozen layer of liquid material via an ice film on an upright freezing and heating surface, For the first time, fully automatic, unmanned operation of a closed device has become possible.

Moreover, the frozen layer of liquid material obtained by this embodiment is particularly advantageous for freeze-drying.
The characteristics of homogeneous acicular ice crystals growing upright from the freezing/heating surface without supercooling because the liquid at the freezing point temperature is supplied onto the ice film are shown in Figures 1 and 2. This is a common advantage with the embodiment shown in Fig. 2, but in addition, in the embodiment shown in Figs. 3 to 6, a part of the supplied liquid material flows down unfrozen, so that The tips of the needle ice crystals are mostly exposed without being covered by the concentrated liquid phase or eutectic. Therefore, the impermeable membrane that prevents the passage of water vapor from the sublimation surface is extremely weak.

Conventionally, in order to avoid this difficult-to-perme membrane, nylon gauze was pressed onto the surface of the supplied liquid layer and then peeled off after freezing.
Cumbersome methods such as spraying water at ℃ onto the surface to dilute the highly concentrated membrane were tried, but in the end,
The only method that has been put into practical use is to crush the frozen material into 1-3 mm frozen particles and then fill them into trays. The formation of a poorly permeable membrane not only slows down the drying rate, but also causes uneven drying depending on when and where the membrane breakdown occurs.

Due to the above characteristics, the apparatus shown in FIGS. 3 to 6 can be effectively used for high-quality concentration of liquid materials. That is, concentration is performed by interrupting freeze-drying when a frozen layer still remains over the entire material layer. When concentrated by evaporation, much of the aromatic components are lost because it is more volatile than water. However, in the sublimation process of freeze-drying, the aromatic components are adsorbed on the concentrated liquid phase side, so they do not disappear, but in the drying process of the dried porous layer after sublimation.
Some of it evaporates along with the water. Utilizing this known principle, partial freeze-drying for the purpose of concentration has heretofore been carried out in part. However, firstly, it is complicated to handle because it depends on the tray.
Second, due to the inhomogeneous ice crystals during freezing, the drying process becomes patchy, with a thick frozen layer remaining in some parts, while in others, the frozen layer has completely disappeared and the aromatic components are lost. As secondary drying progressed with The means of the present invention also eliminates the above two points conceded.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional side view of the essential parts of the vacuum freeze-drying apparatus used to implement the method of the present invention, Fig. 2 is a perspective view of the main parts of the same in a state in which dried products are taken out, and Fig. 3a is an implementation of another embodiment. Example Cross-sectional plan view of the main parts of the device, No. 3
Fig. 4b is a vertical cross-sectional side view taken along line S-S' in Fig. 3a of the main part of the same, Fig. 4a is a cross-sectional plan view of the main part of the apparatus of a different embodiment, and Fig. 4b is a cross-sectional side view of the main part of the same. 4a is a longitudinal cross-sectional side view taken along line S-S' in FIG.
Figure a is a transverse cross-sectional view of the main part of the embodiment of the apparatus which is a modification of the configuration shown in Figures 3 a and 4 b and Figure 4 a and b;
FIG. 6b is a longitudinal cross-sectional side view taken along line S-S' of the main part of the same. Explanation of drawing symbols a...Drying chamber, b...Cylinder, 1...
Freezing/heating surface, 1a... Shelf, 10... Freezing layer, 11...
Inside, 12...Outside, 13...Water tank, 14...Ciel, 15...Product tank, 16...Lower door, 16a...Hinge, 17...Upper door, 18...Trap, 19...Support, 2...Frame, 20...Liquid supply Tank, 21... Trap chamber, 22... Pipe line, 23... Water inlet, 24... Drain port, 25... Product receiver, 3... Water injection mechanism, 3a... Spray nozzle, 30... Liquid receiving tank, 4... Drying room, 4a... Opening port, 5... Product receiver, 6... Drive section, 7... Low friction rail, 8... Dry product, 100... Supply source of stock solution.

Claims (1)

[Claims] 1. Water is poured onto the freezing surface of a freezing and heating surface installed in the drying chamber of a vacuum freeze-drying device, and the freezing surface is heated to zero.
℃ or below to form an ice film on the frozen surface, and while continuing to maintain the frozen surface at a sufficiently low temperature of 0°C or below, supply a liquid or flat material to be dried onto the ice film. A freeze-drying method characterized in that the material to be dried is frozen on the ice film, and then the drying chamber is evacuated and the frozen layer of the material to be dried and the ice film are dried under a vacuum condition. 2. Pour water onto the inner surface of the container for the material to be dried, which is placed in the drying chamber of the vacuum freeze-drying equipment, and place the container at zero temperature.
℃ or below to form an ice film on the inner surface of the container, and while continuing to maintain the container at a sufficiently low temperature of 0°C or below, supplying a liquid or flat material to be dried onto the ice film, A freeze-drying method in which the material to be dried is frozen on the ice film, the drying chamber is then evacuated, and the frozen layer of the material to be dried and the ice film are dried under a vacuum condition. 3. A drying chamber whose interior is maintained at a normal degree of vacuum, a freezing/heating surface configured as a single or multi-level horizontal shelf within the drying chamber, and a material to be dried fixed or movably arranged on the shelf. frame for
A water injection mechanism that sprays water almost evenly onto the shelf surface surrounded by the frame arranged on the shelf surface and the contact area between the frame and the shelf surface, and a door surface located at the front of the shelf. A vacuum freeze-drying device comprising: 4. A drying chamber whose interior is maintained at a normal degree of vacuum, and a single or multiple upright surfaces within the drying chamber, such as an upright cylindrical surface (inner cylindrical surface or outer cylindrical surface), or
A freezing and heating surface configured as an upright plane, a water supply and drainage mechanism that supplies and discharges water almost evenly to the freezing and heating surface, and a liquid material to be dried that is supplied and discharged to the space above the freezing and heating surface. 1. A vacuum freeze-drying apparatus comprising: a liquid supply/drainage mechanism; and a door surface located at a lower end surface of the drying chamber.