Drying system and drying method

Abstract

To provide a drying system and a drying method capable of grasping a drying state.SOLUTION: A drying system 1 includes a vessel body 21 for storing a frozen object F obtained by freezing a treated material, a heating medium temperature adjustment unit 3 and stirring means 22 for drying the frozen object F by sublimating a solidified liquid component contained in the frozen object F stored in the vessel body 21 into steam, a cold trap 5 for receiving the steam and freezing the steam into a solid so as to be collected, and a load cell 56 and control means 10 for monitoring a collection state of the solid in the cold trap 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drying system and a drying method for drying a frozen object by freezing an object to be treated and sublimating a solidified liquid component contained in the frozen object. [Background technology]

[0002] Vacuum freeze-drying technology is known, which freezes materials (hereinafter referred to as the object to be processed) used in foods, cosmetics, medical products, raw materials for electronic components, chemical products, paints, etc., to produce a frozen product, and then sublimates the solidified liquid components contained in the frozen product to obtain a dried product. A typical system using this vacuum freeze-drying technology is a shelf-type drying system. In a shelf-type drying system, shelves are provided in a drying container for placing frozen products, and the temperature of the shelves is adjusted to an appropriate temperature under reduced pressure to dry the frozen product while it is still frozen to obtain a dried product. In the shelf-type drying system, a cold trap is provided in the exhaust path between the drying container and the vacuum pump to prevent the liquid components that have become vaporized by sublimation from reaching the vacuum pump. The inside of this cold trap is cooled by circulating a refrigerant cooled by a refrigerator. The liquid components that have become vaporized in the drying container freeze to solidify as they pass through the cold trap, and are collected by the cold trap.

[0003] In a shelf-type drying system, a tray containing the object to be processed is placed on a shelf and frozen to obtain a frozen product. After that, the pressure inside the drying container is reduced to sublimate the solidified liquid components contained in the frozen product. At that time, the shelf on which the tray is placed is heated to supply heat to the frozen product to promote drying. However, if the product is heated too much, the solidified liquid components contained in the frozen product melt and lumps (aggregations of the object to be processed) form in the dried product, which reduces the quality, so the amount of heat supplied to the frozen product by heating is set to a level that compensates for the heat taken away by sublimation. In addition, when the dried product is dispersed in a liquid, the dried product is required to have good restorability (water reconstitution) so that it can return to the same state as before drying. However, if lumps form, the restorability (water reconstitution) is impaired. In a shelf-type drying system, the frozen product in the tray basically receives heat only from the bottom side where the shelf is located, so the part of the frozen product that receives heat is always the same part, and that part is prone to melting. Even if only the bottom side of the frozen product melts, a small amount of lumps will be mixed into the dried product, which reduces the quality of the dried product. For this reason, in a shelf-type drying system, it is necessary to heat the material while significantly suppressing the amount of heat supplied (heating temperature) to prevent lumps from forming, so it takes a long time to dry the material. The shelf-type drying system described here can be said to be a static drying system in which the frozen material does not move.

[0004] On the other hand, a drying system has been proposed in which the material to be processed is frozen to obtain a frozen material consisting of a number of blocks of material, and the frozen material is dried while being moved (see, for example, Patent Document 1). The drying in this drying system can be said to be dynamic drying. In the drying system of Patent Document 1, the frozen material stored in a drying container is dried while being moved in the drying container, so that heat can be applied uniformly to the surface of the frozen material, and therefore a larger amount of heat can be supplied to the frozen material (higher heating temperature) compared to a shelf-type drying system, and the drying time is shortened. In addition, frictional heat is generated between the frozen materials by moving the frozen material, so that the frozen material is heated in areas other than those where heat from the outside is transmitted, and the drying time is further shortened. Even in a dynamic drying system such as Patent Document 1, liquid components that have become vapor are collected by a cold trap installed in the exhaust path between the drying container and the vacuum pump. In addition, whether the drying system is static or dynamic, it is confirmed that the drying is completed and the frozen material has become the desired dried material by the disappearance of pressure fluctuations in the drying container and the exhaust path and temperature fluctuations of the frozen material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-72411 Summary of the Invention [Problem to be solved by the invention]

[0006] As the drying process nears the end, less liquid components turn into vapor, and therefore less vapor is captured by the cold trap. As the refrigerant circulating between the refrigerator and the cold trap is no longer heated by the cold trap, the refrigerator that cools the cold trap goes into a low-pressure cut state, and the refrigerant's cooling function stops. After the low-pressure cut state is reached, the refrigerant pressure rises over time, and the refrigerator is no longer stopped, so the refrigerator is repeatedly stopped and restarted. This causes the temperature and pressure of the cold trap to fluctuate, which in turn causes the pressure and temperature inside the drying vessel and in the exhaust path to fluctuate, making it difficult to determine whether the drying is complete.

[0007] In addition, at the end of the drying process, the liquid content of the frozen material is reduced, so the risk of the frozen material melting is reduced. For this reason, in a dynamic drying system, there is a demand to shorten the drying time by increasing the speed and frequency at which the frozen material is moved. However, as described above, the pressure and temperature in the drying container and the exhaust path fluctuate depending on the operation of the refrigerator, so it is difficult to know when the drying process is at the end from the measurement results of the pressure and temperature, and as a result, there is a problem that the speed and frequency at which the frozen material is moved cannot be increased.

[0008] In view of the above circumstances, an object of the present invention is to provide a drying system and a drying method that make it possible to grasp the drying status. [Means for solving the problem]

[0009] The drying system of the present invention which solves the above problems includes: A container body for storing a frozen object obtained by freezing the object to be processed; A drying means for drying the frozen object by sublimating a solidified liquid component contained in the frozen object stored in the container body into vapor; a cold trap that receives the vapor and freezes the vapor into a solid form for collection; and a monitoring means for monitoring the state of capture of the solid in the cold trap.

[0010] According to this drying system, the generation state of the steam can be known by monitoring the collection state, so that the drying state of the frozen material can be grasped.

[0011] Here, the drying system may include a refrigerator that circulates a refrigerant between the cold trap and the refrigerator. The refrigerator may be temporarily stopped when the pressure of the refrigerant returning from the cold trap is reduced. The drying means may include a frozen object operating unit that moves the frozen object within the container body.

[0012] In this drying system, The monitoring means may monitor a change in mass of the solid matter trapped in the cold trap.

[0013] When the amount of liquid component decreases and the amount of steam generated decreases, the mass of the solid collected in the cold trap also decreases, so the drying status of the frozen material can be understood by monitoring the change in the mass of the solid.

[0014] In addition, in this drying system, the cold trap has a cooling tube to which the solid adheres; The monitoring means may monitor a change in thickness of the solid material attached to the cooling pipe.

[0015] When the liquid component decreases and the steam generation decreases, the amount of solid adhering to the cooling pipe also decreases, so the drying status of the frozen material can be grasped by monitoring the change in the thickness of the solid.

[0016] In addition, in this drying system, the cold trap has a cooling tube to which the solid adheres; The monitoring means may monitor a change in shape of the solid material attached to the cooling pipe.

[0017] When the liquid component is reduced and the steam generation is reduced, the amount of solid adhering to the cooling pipe is also reduced, so by monitoring the change in the shape of the solid, the drying status of the frozen material can be grasped.

[0018] In addition, in this drying system, A plurality of said cold traps; a switching means for switching the cold trap that receives the steam among the plurality of cold traps, The monitoring means may monitor the collection status by measuring a mass of the solids collected by the cold trap that had received the steam before the switching means switched the cold trap.

[0019] In this way, the drying state of the frozen object can be accurately grasped. Here, the switching means may select one of the plurality of cold traps.

[0020] In addition, in this drying system, a jacket covering the outer periphery of the container body and through which a heat medium flows to supply heat to the frozen material contained in the container body; The apparatus may further include a control means for adjusting the amount of heat supplied from the heat medium to the frozen object in accordance with the collection state.

[0021] The control means controls the supply of heat to the frozen material in an amount appropriate for the drying state of the frozen material in response to the collection state, thereby making it possible to shorten the drying time.

[0022] In addition, in this drying system, a frozen object operating unit that moves the frozen object stored in the container body within the container body; The apparatus may further include a control means for adjusting at least one of the speed at which the frozen object is moved by the frozen object operating unit and the frequency at which the frozen object is moved in accordance with the collection status.

[0023] The control means controls the movement of the frozen material at a speed and frequency suited to the drying condition of the frozen material in response to the collection condition, thereby making it possible to shorten the drying time.

[0024] The drying method of the present invention which solves the above problems includes: A drying method for a drying system including a container body for storing a frozen material obtained by freezing an object to be processed, and a drying means for drying the frozen material by sublimating a solidified liquid component contained in the frozen material stored in the container body into vapor, the drying method comprising: a capture step of freezing the vapor to form a solid and capture it; and a monitoring step of monitoring the state of capture of the solid in the capture step.

[0025] According to this drying method, by monitoring the collection status in the monitoring step, it is possible to grasp the drying status of the frozen material. Effect of the Invention

[0026] According to the present invention, it is possible to provide a drying system and a drying method that make it possible to grasp the drying status. [Brief description of the drawings]

[0027] [Figure 1] 1 is a system diagram of a drying system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a control configuration of the drying system shown in FIG. [Diagram 3] 2 is a flowchart showing control in a drying process of the drying system shown in FIG. 1. [Figure 4]FIG. 13(a) is a simplified cross-sectional view showing a schematic diagram of a cold trap in a drying system according to a first modified example, and FIG. 13(b) is a simplified cross-sectional view showing a schematic diagram of a cold trap in a drying system according to a second modified example. [Diagram 5] 4 is a flowchart similar to FIG. 3, illustrating control in a drying process in the drying system of the first modified example. [Figure 6] 10 is a flowchart similar to FIG. 3, illustrating control in a drying process in a drying system according to a second modified example. [Figure 7] FIG. 11 is a system diagram similar to FIG. 1, showing a drying system according to a third modified example. [Figure 8] FIG. 13 is a diagram showing a heat medium temperature adjuster in a drying system according to a fourth modified example. [Figure 9] FIG. 13 is a diagram showing a heat medium temperature adjuster in a drying system according to a fifth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drying system according to an embodiment of the present invention will now be described in detail with reference to the drawings. The drying system described below is a system for freezing a processing object and drying the frozen object.

[0029] FIG. 1 is a system diagram of a drying system 1 according to one embodiment of the present invention. In the upper right part of FIG. 1, a table is shown showing the correspondence between symbols of the elements constituting the drying system 1, such as valves and instruments, and the names of the components indicated by the symbols. Since the components indicated by these symbols and their functions are well known, some of them will not be described in the description of this embodiment. Furthermore, the measurement results of the components indicated by these symbols that belong to the instruments are appropriately transmitted to control means 10 (see FIG. 2). In addition, the opening and closing and the opening degree of the motor-operated valves, among the components indicated by these symbols, are controlled by control means 10.

[0030] 1 includes a drying container 2, a heat medium temperature adjusting section 3, a vacuum pump 4, a cold trap 5, a common refrigerator 6, and a heat exchanger 7. An example of the heat exchanger 7 is a cooling tower.

[0031] The drying container 2 has a container body 21, a stirring means 22, and a jacket 23. In Fig. 1, the container body 21 is shown in a schematic vertical cross section so that the inside can be seen. In Fig. 1, the frozen material F in the container body 21 is shown by a dot pattern.

[0032] The container body 21 is supported by a support pillar (not shown). The container body 21 is composed of a cylindrical upper portion, an inverted cone-shaped portion that gradually reduces in diameter as it moves away from the upper portion, and an upper lid that covers the upper end. The container body 21 is also provided with a container thermometer 211 that measures the temperature of the stored items such as the brine liquid and frozen items F stored inside, and a brine liquid outlet 212. The container thermometer 211 constantly measures the temperature of the stored items. The lower end of the container body 21 is provided with an outlet 213 for discharging the stored items. The outlet 213 is closed by an outlet lid 214 that can be opened and closed except when discharging the stored items.

[0033] The upper lid of the container body 21 is provided with an inlet 215, an exhaust port 216, and a vortex breaker 217. For example, a dispersion liquid in which the material to be treated is dispersed in a liquid is introduced into the container body 21 through the inlet 215. Then, the dispersion liquid is frozen while being stirred in the container body 21, and a frozen material F consisting of a number of processed material chunks is generated. Note that a brine liquid is stored in the container body 21 before the dispersion liquid is introduced, and the dispersion liquid is frozen in the brine liquid, and then only the brine liquid is drained from the brine liquid outlet 212, so that the frozen processed material chunks remain in the container body 21. However, the frozen material F may be prepared using a dispersion liquid in another device, and the frozen material F may be directly introduced into the empty container body 21 through the inlet 215 and stored in the container body 21. Also, the material to be treated containing a liquid component may be directly frozen in the container body 21 without using a dispersion liquid to produce the frozen material F. Furthermore, the object to be processed containing a liquid component may be directly frozen in another device without using a dispersion liquid to prepare a frozen object F, which may then be introduced into the empty container body 21 through the introduction port 215 and stored in the container body 21. In this embodiment, ethanol is used as the brine liquid, but instead of ethanol, organic compounds such as paraffins, alicyclic hydrocarbons, alcohols, and ethers having a melting point of −30° C. or lower and a boiling point of less than 100° C. may be used.

[0034] The exhaust port 216 is for discharging gas such as air in the container body 21 and steam generated in the container body 21. The exhaust port 216 is connected to an upstream exhaust path 511 via an exhaust filter (not shown). Gas that has passed through the exhaust filter enters the upstream exhaust path 511. A cold trap 5 is connected downstream of the upstream exhaust path 511. A vacuum pump 4 is installed downstream of the cold trap 5 via a downstream exhaust path 512. The upstream exhaust path 511, the cold trap 5, and the downstream exhaust path 512 form an exhaust path. The upstream exhaust path 511 is provided with an exhaust path pressure gauge 513, which is a vacuum gauge that measures the pressure in the upstream exhaust path 511. The pressure in the upstream exhaust path 511 measured by the exhaust path pressure gauge 513 is constantly transmitted to the control means 10 (see FIG. 2). Note that instead of or in addition to the exhaust line pressure gauge 513, a pressure gauge may be installed to measure the pressure inside the vessel body 21, the pressure inside the cold trap 5, or the pressure of the downstream exhaust line 512. Note that the pressure inside the vessel body 21, the pressure inside the upstream exhaust line 511, the pressure inside the cold trap 5, and the pressure inside the downstream exhaust line 512 are all gas pressures.

[0035] The vortex current breaker 217 is attached to the lower end of a shaft hanging down from the upper lid of the container body 21. The vortex current breaker 217 is disposed at a position facing the cylindrical upper part of the container body 21 with a gap therebetween, and is composed of an arc-shaped plate that follows the cylindrical shape of the upper part. The vortex current breaker 217 guides the frozen material F that has reached the top of the container body 21 downward.

[0036] The stirring means 22 has a rotating spiral ribbon 221, a stirring drive shaft 222, and a stirring drive device 223. This stirring means 22 corresponds to an example of a frozen material operating unit. The spiral ribbon 221 is made entirely of metal, is supported by a plurality of rod-shaped support members protruding radially from the stirring drive shaft 222, and travels around the inner surface of the container body 21 in the vicinity of the inner surface of the container body 21. The spiral ribbon 221 may be made of a resin such as engineering plastic or fiber-reinforced plastic. The spiral ribbon 221 has a spiral shape that tapers downward. This spiral ribbon 221 rotates as the stirring drive shaft 222 rotates around its axis. The stirring drive shaft 222 penetrates the upper lid of the container body 21, and the penetration portion is sealed. The stirring drive device 223 is a motor that rotates the stirring drive shaft 222. The agitation drive shaft 222 rotates around its axis by driving the agitation drive device 223, thereby rotating the spiral ribbon 221. The rotation of the spiral ribbon 221 generates a circulatory flow of the frozen material F stored in the container body 21. That is, the rotation of the spiral ribbon 221 causes the frozen material F located near the inner surface of the container body 21 to be lifted upward, and the frozen material F located in the center part in a plan view of the container body 21 to move downward. This causes the frozen material F stored in the container body 21 to be agitated. By increasing the rotation speed of the spiral ribbon 221, that is, the agitation rotation speed of the frozen material F, the frozen material F is lifted further upward, and the flow speed in the circulatory flow of the frozen material F increases, so that the frozen material F is moved more at a faster speed.

[0037] The jacket 23 covers the outer periphery of the container body 21. A heat medium supply path 231 and a heat medium recovery path 232 are connected to the jacket 23. The heat medium supply path 231 has a leading end connected to the lower part of the jacket 23 and a rear end connected to the heat medium temperature adjustment unit 3. On the other hand, the heat medium recovery path 232 has a leading end connected to the heat medium temperature adjustment unit 3 and a rear end connected to the upper part of the jacket 23. The heat medium supplied to the jacket 23 through the heat medium supply path 231 flows inside the jacket 23 and is discharged to the heat medium recovery path 232. The outside of the jacket 23 is covered with a heat insulating member (not shown) so that the temperature of the heat medium in the jacket 23 does not change depending on the installation environment of the drying container 2.

[0038] The heat medium temperature adjustment unit 3 includes a heat medium pump 31, a cooling flow rate adjustment valve 33, a constant flow rate valve 34, a heat medium cooler 35, a heat medium heater 36, a heat medium tank 37, and a heat exchanger 38. In FIG. 1, the heat medium temperature adjustment unit 3 is surrounded by a two-dot chain line. This heat medium temperature adjustment unit 3 corresponds to an example of a supply heat amount adjustment unit. In addition, in FIG. 1, the heat medium cooler 35 and the heat medium heater 36 are shown in a schematic cross section cut vertically so that the inside can be seen. The heat medium pump 31 delivers the liquid heat medium at an arbitrary flow rate. The heat medium is ethanol, which is the same as the above-mentioned brine liquid. Of course, the heat medium may be other than ethanol, and may be different from the brine liquid. The delivered heat medium is divided into the heat medium cooler 35 and the heat medium heater 36 at the divided flow rates set by the cooling flow rate adjustment valve 33 and the constant flow rate valve 34, respectively. The constant flow valve 34 is a valve that allows the heat medium to flow at a set flow rate.

[0039] The cooling flow rate control valve 33 is an electric valve that changes the flow rate of the heat medium passing therethrough under the control of the control means 10 (see FIG. 2), which will be described later. The cooling flow rate control valve 33 can be closed to set the flow rate to zero, and by setting it to zero, the heat medium flows only to the heat medium heater 36. The control means 10 adjusts the flow rate sent out by the heat medium pump 31 according to the opening degree of the cooling flow rate control valve 33 so that the flow rate of the heat medium toward the heat medium heater 36 is always constant. Under the control of the control means 10, a constant amount of the heat medium always flows to the heat medium heater 36, and a flow rate according to the opening degree of the cooling flow rate control valve 33 flows to the heat medium cooler 35. The heat medium that has passed through the heat medium heater 36 is supplied to the jacket 23 through the heat medium supply path 231, so that a constant amount of the heat medium always circulates between the jacket 23 and the heat medium temperature adjustment unit 3. The flow rate toward the heat medium heater 36 may be changed by adjusting the flow rate sent out by the heat medium pump 31 and the opening degree of the cooling flow rate control valve 33. Alternatively, instead of or in addition to the constant flow valve 34, an electric valve may be disposed in the flow path toward the heat medium heater 36, thereby making it possible to form a flow of the heat medium toward only the heat medium cooler 35.

[0040] The heat medium cooler 35 cools the heat medium passing through it. The heat medium cooled by passing through this heat medium cooler 35 passes through the heat exchanger 38 and flows toward the heat medium tank 37. A refrigerant circulates between the heat medium cooler 35 and the common refrigerator 6. The refrigerant cooled by the common refrigerator 6 is sent to the heat medium cooler 35, where it is heated by the heat medium and returned to the common refrigerator 6. That is, in the heat medium cooler 35, the heat medium is cooled and the refrigerant is heated. A cooler expansion valve 351 is provided immediately before the heat medium cooler 35 in the refrigerant flow. The high-pressure refrigerant cooled by the common refrigerator 6 is decompressed by this cooler expansion valve 351 to a state where it is easy to evaporate, and the amount set by the cooler expansion valve 351 flows to the heat medium cooler 35. The flow of this refrigerant will be described later. The outside of the heat medium cooler 35 is covered with a heat-insulating member. In FIG. 1, the heat retaining member is shown by cross-hatching.

[0041] The heat medium heater 36 heats the heat medium passing through it. However, the heat medium heater 36 can also pass the heat medium as it is without heating it. The heat medium that has passed through the heat medium heater 36 flows toward the jacket 23 through the heat medium supply path 231. The heat medium heater 36 is provided with a heating thermometer 361 that measures the heating temperature at which the heat medium is heated. In addition, a heat medium thermometer 362 that measures the temperature of the heat medium that has passed through the heat medium heater 36 is provided downstream of the heat medium heater 36 in the flow of the heat medium. The measured values ​​of these thermometers are constantly transmitted to the control means 10 (see FIG. 2). The control means 10 controls the heating temperature of the heat medium by the heat medium heater 36 based on these measured values ​​so that the heat medium flowing from the heat medium heater 36 toward the jacket 23 has a desired temperature. The heat medium heater 36 is covered on the outside with a heat retaining member. In FIG. 1, the heat retaining member is indicated by cross-hatching.

[0042] The heat medium tank 37 stores the heat medium returned from the jacket 23 through the heat medium recovery path 232 and the heat medium that has passed through the heat medium cooler 35. The heat medium stored in the heat medium tank 37 is extracted at a desired flow rate by the heat medium pump 31 and sent out from the heat medium pump 31. The heat medium sent out from the heat medium pump 31 flows toward the branch section 32 that branches into the heat medium cooler 35 and the heat medium heater 36.

[0043] The heat exchanger 38 exchanges heat between the cooling water flowing from the common refrigerator 6 toward the heat exchanger 7 and the heat medium flowing from the heat medium cooler 35 toward the heat medium tank 37. A waste heat supply valve 381, which is an electric valve that adjusts the flow rate of the cooling water toward the heat exchanger 38, is provided in the front stage (upstream side) of the heat exchanger 38 in the flow of the cooling water. The opening degree of the waste heat supply valve 381 is controlled by the control means 10 (see FIG. 2). In addition, a bypass path that connects the front stage (upstream side) and the rear stage (downstream side) of the heat exchanger 38 in the flow of the cooling water is formed in the vicinity of the heat exchanger 38. The bypass path is provided with a waste heat bypass valve 382, ​​which is an electric valve. The opening degree of the waste heat bypass valve 382 is also controlled by the control means 10. When heat exchange is not required, the waste heat supply valve 381 is closed and the waste heat bypass valve 382 is opened, so that the cooling water flows toward the heat exchanger 7 without passing through the heat exchanger 38. Conversely, when heat exchange is required, the waste heat supply valve 381 is opened and the waste heat bypass valve 382 is closed, so that the cooling water flows toward the heat exchanger 7 after passing through the heat exchanger 38. When only a portion of the cooling water is to be heat exchanged, the ratio of the flow rate of the cooling water that is heat exchanged in the heat exchanger 38 to the flow rate of the cooling water that is not heat exchanged can be set arbitrarily by adjusting the opening degree of each of the waste heat supply valve 381 and the waste heat bypass valve 382.

[0044] The heat medium temperature adjustment unit 3 circulates the heat medium, the temperature of which is adjusted to a set temperature mainly by the heat medium cooler 35 and the heat medium heater 36, between the jacket 23 and the heat medium temperature adjustment unit 3. That is, the temperature-adjusted heat medium is repeatedly circulated, such as being supplied to the jacket 23 through the heat medium supply path 231, and then being returned from the jacket 23 to the heat medium temperature adjustment unit 3 through the heat medium recovery path 232. By circulating and supplying the heat medium to the jacket 23, the temperature of the container body 21 can be adjusted from the outside, and the temperature inside the container body 21 can be adjusted to a desired temperature. That is, the heat medium temperature adjustment unit 3 adjusts the amount of heat supplied to the frozen object F from the heat medium flowing between the jacket 23 and the heat medium temperature adjustment unit 3. The heat medium temperature adjustment unit 3 can adjust both the temperature and flow rate of the heat medium, and can adjust the amount of heat supplied to the frozen object F in the container body 21 by either of these. However, in this embodiment, an example will be described in which the flow rate of the heat medium supplied to the jacket 23 is controlled to be constant, and the amount of heat supplied to the frozen object F in the container body 21 is adjusted by adjusting the temperature of the heat medium. Although the heat medium temperature adjusting unit 3 mainly supplies heat to the frozen object F, it can also be used to cool the brine liquid in the container body 21, which will be described later in detail.

[0045] The vacuum pump 4 reduces the pressure in the container body 21, the upstream exhaust path 511, the cold trap 5, and the downstream exhaust path 512. Hereinafter, the container body 21, the upstream exhaust path 511, the cold trap 5, and the downstream exhaust path 512 may be collectively referred to as the container body 21. The vacuum pump 4 is provided at the downstream end of the flow of gas that has passed through the exhaust port 216 of the container body 21. The vacuum pump 4, the heat medium temperature adjustment unit 3, and the stirring means 22 correspond to an example of a drying means. By driving the vacuum pump 4, the solidified liquid component contained in the frozen material F in the container body 21 sublimes and becomes vapor. In addition, the solidified liquid component contained in the frozen material F sublimes and becomes vapor when the frozen material F is heated by the heat medium whose temperature is adjusted by the heat medium temperature adjustment unit 3, or when the frozen material F is heated by frictional heat generated by the rotation of the spiral ribbon 221. The steam generated in the container body 21 and gases such as air that were in the container body 21 are drawn toward the vacuum pump 4. Then, the gases that reach the vacuum pump 4 are exhausted to the outside of the vacuum pump 4. However, liquid components contained in the gases are collected by the cold trap 5 before they reach the vacuum pump 4.

[0046] By driving the vacuum pump 4, the pressure inside the container body 21 and the like is reduced to about 13 Pa or more and 120 Pa or less. In order to prevent this pressure from dropping too much, the downstream exhaust path 512 is connected to the intake path 41, which draws in outside air. The intake path 41 is provided with a pressure regulating valve 42, which is an electric valve. If the pressure inside the upstream exhaust path 511 measured by the exhaust path pressure gauge 513 is too low, the control means 10 (see FIG. 2) adjusts the opening of the pressure regulating valve 42 according to the pressure. As a result, outside air according to the opening of the pressure regulating valve 42 passes through the intake path 41 and enters the downstream exhaust path 512, so that the pressure inside the container body 21 and the like is maintained at 13 Pa or more and 120 Pa or less. An intake filter 43 for reducing intake noise and foreign matter contamination is attached to the end of the intake path 41 opposite to the end connected to the downstream exhaust path 512.

[0047] The downstream exhaust passage 512 is provided with an oxygen concentration meter 44 for measuring the oxygen concentration in the downstream exhaust passage 512. Since the steam generated in the container body 21 is almost oxygen-free, the oxygen concentration in the downstream exhaust passage 512 changes mainly depending on the amount of outside air sucked through the intake passage 41. At the beginning and middle of the drying process, the amount of steam generated from the frozen object F is large, so the pressure inside the container body 21 and the like is increased by the pressure increase action of the steam generated in the container body 21 and the pressure reduction action of the vacuum pump 4 are in balance, and the amount of outside air sucked through the intake passage 41 is zero or very small. On the other hand, at the end of the drying process, the liquid component contained in the frozen object F is reduced, so the steam generated in the container body 21 is greatly reduced. As a result, at the end of the drying process, the amount of outside air sucked through the intake passage 41 increases, and the oxygen concentration in the downstream exhaust passage 512 increases.

[0048] The cold trap 5 is for freezing and collecting the received vapor. In FIG. 1, the cold trap 5 is shown in a schematic vertical cross section so that the inside can be seen. Basically, vapor freezes by sublimation (solidification) in the cold trap 5, but a very small amount of vapor may condense (liquefy) and then solidify (freeze) to become a solid. A refrigerant circulates between the cold trap 5 and the common refrigerator 6. This refrigerant is a refrigerant that is used in common with the refrigerant circulating between the heat medium cooler 35 and the common refrigerator 6. A part of the refrigerant cooled in the common refrigerator 6 is sent to the cold trap 5, passes through the cooling pipe 51 that is folded back multiple times in the cold trap 5, and then returns to the common refrigerator 6. A trap expansion valve 55 is provided immediately before the cold trap 5 in the refrigerant flow. The high-pressure refrigerant cooled in the common refrigerator 6 is decompressed by the trap expansion valve 55 to a state that is easy to evaporate, and the amount set by the trap expansion valve 55 flows into the cooling pipe 51. The steam passing through the cold trap 5 is cooled and frozen in the cooling tube 51, and adheres to the surface of the cooling tube 51, and the thickness of the adhesion gradually increases from the surface of the cooling tube 51. The outside of the cold trap 5 is covered with a heat-insulating material. In Fig. 1, the heat-insulating material is indicated by cross-hatching.

[0049] The cold trap 5 is provided with a trap thermometer 53 for measuring the temperature inside the cold trap 5. The cold trap 5 is also provided with a load cell 56 for measuring the mass of the vapor generated by the sublimation of the liquid component of the frozen object F and collected by the cold trap 5. In order to measure the mass with the load cell 56, a flexible hose 54 is installed in the vicinity of the cold trap 5 of each pipe connected to the cold trap 5. The load cell 56 measures the mass of the part located closer to the cold trap 5 than the flexible hose 54, and constantly transmits the measurement result to the control means 10 (FIG. 2). The load cell 56 and the control means 10 correspond to an example of a monitoring means. In this embodiment, the load cell 56 measures the total mass of the part located closer to the cold trap 5 than the flexible hose 54 and the collected vapor, and transmits it to the control means 10, and the control means 10 calculates the mass of the collected vapor. However, the mass of the collected vapor may be directly measured by the cold trap 5 and transmitted to the control means 10 by setting the mass of the vapor before collection to zero in the load cell 56 .

[0050] The common refrigerator 6 supplies refrigerant to both the heat medium cooler 35 and the cold trap 5. The common refrigerator 6 has a refrigerant compression cooling section 61 and a refrigerant pressure gauge 62. The refrigerant returning from the heat medium cooler 35 and the refrigerant returning from the cold trap 5 join in a refrigerant recovery passage 64 to become a mixed refrigerant. The refrigerant compression cooling section 61 compresses the mixed refrigerant to a high pressure, and cools the refrigerant that has become hot by compression with cooling water to condense it and send it to the refrigerant supply passage 63. The refrigerant supply passage 63 branches into a cooler refrigerant supply passage 631 leading to the heat medium cooler 35 and a trap refrigerant supply passage 632 leading to the cold trap 5. The cooler refrigerant supply passage 631 is provided with a cooling refrigerant supply valve 633. The cooling refrigerant supply valve 633 is operated under the control of the control means 10 (see FIG. 2), and is a valve that opens when the supply of refrigerant to the heat medium cooler 35 starts and closes when the supply is stopped. The cooler expansion valve 351 described above is disposed between the cooling refrigerant supply valve 633 and the heat medium cooler 35. The refrigerant, which has expanded in the cooler expansion valve 351 to become a low-pressure liquid, evaporates into gas by cooling the heat medium in the heat medium cooler 35, and is then returned to the common refrigerator 6 through the refrigerant recovery path 64. Note that if the heat medium does not pass through the heat medium cooler 35, if the amount of heat medium passing through the heat medium cooler 35 is small, or if the heat medium passing through the heat medium cooler 35 is sufficiently cooled, some or all of the refrigerant may return to the common refrigerator 6 from the heat medium cooler 35 in liquid form.

[0051] Further, the trap refrigerant supply passage 632 is provided with a trap refrigerant supply valve 634. This trap refrigerant supply valve 634 is operated under the control of the control means 10 (see FIG. 2), and is a valve that opens when the supply of refrigerant to the cold trap 5 is started and closed when the supply is stopped. The above-mentioned trap expansion valve 55 is disposed between the trap refrigerant supply valve 634 and the cold trap 5. The refrigerant that has expanded to a low-pressure liquid by the trap expansion valve 55 flows into the cooling pipe 51 in the cold trap 5, freezes the vapor, and evaporates to a gas, and is then returned to the common refrigerator 6 through the refrigerant recovery passage 64. Note that when the amount of vapor received by the cold trap 5 decreases, a part or all of the refrigerant may return from the cold trap 5 to the common refrigerator 6 in a liquid state.

[0052] The refrigerant recovery path 64 is a refrigerant flow path formed by joining a cooler refrigerant recovery path 641 connected to the heat medium cooler 35 and a trap refrigerant recovery path 642 connected to the cold trap 5. The refrigerant that joins in the refrigerant recovery path 64 flows into the refrigerant compression and cooling section 61. The refrigerant pressure gauge 62 measures the pressure of the refrigerant after the refrigerant recovery path 64 joins and before the refrigerant flows into the refrigerant compression and cooling section 61. That is, the refrigerant pressure gauge 62 measures the pressure of the low-pressure side of the refrigerant.

[0053] As the drying process approaches the end, the liquid component contained in the frozen material F decreases, and the vapor generated in the container body 21 also decreases. As a result, the amount of vapor collected in the cold trap 5 decreases, and the refrigerant circulating between the cold trap 5 and the common refrigerator 6 is no longer heated in the cold trap 5. As the drying process progresses further, the temperature of the refrigerant hardly increases in the cold trap 5, and the pressure of the refrigerant measured by the refrigerant pressure gauge 62 decreases. When the pressure of the refrigerant measured by the refrigerant pressure gauge 62 falls below a predetermined pressure, the low pressure cut state is entered and the common refrigerator 6 stops the operations of refrigerant compression, refrigerant cooling, and refrigerant circulation. In contrast, in this embodiment, the refrigerant used in common by the heat medium cooler 35 and the cold trap 5 is controlled to be warmed in the heat medium cooler 35, so that the operation of the common refrigerator 6 is not stopped. The details of this control will be described later.

[0054] The heat exchanger 7 is for cooling the cooling water circulating between the common refrigerator 6 and the heat exchanger 7. The heat exchanger 7 is provided with a chemical injection device 71 that injects a chemical to keep the water in the heat exchanger 7 in an optimal state. As described above, the cooling water selectively passes through the heat exchanger 38 on the way from the common refrigerator 6 to the heat exchanger 7, and flows toward the common refrigerator 6 after being cooled by the heat exchanger 7. This flow is formed by the cooling water pump 72 located on the way from the heat exchanger 7 to the common refrigerator 6.

[0055] FIG. 2 is a block diagram showing a control configuration of the drying system 1 shown in FIG.

[0056] As shown in FIG. 2, the control means 10 includes a control unit 101 and a storage unit 102. The control means 10 is a PLC (Programmable Logic Controller). Note that other computers may be used as the control means 10 instead of or in addition to the PLC. Measurement results of various instruments such as the load cell 56, the refrigerant pressure gauge 62, the container thermometer 211, the heat medium thermometer 362, and the exhaust passage pressure gauge 513 are transmitted to the control means 10. The control means 10 controls each of the controlled object configurations such as the heat medium pump 31, the cooling flow rate control valve 33, the heat medium heater 36, the pressure control valve 42, and the agitation drive device 223 provided in the drying system 1 in response to the measurement results by the control unit 101. The control means 10 also performs calculations based on the measurement results of the various instruments as necessary. The storage unit 102 is composed of a volatile memory and a non-volatile memory. The storage unit 102 stores programs and the like that describe the control operations of each controlled object configuration by the control unit 101.

[0057] Next, a description will be given of a drying method for obtaining a dried material by drying the frozen material F using the drying system 1 shown in Fig. 1. The processing in this drying method is executed by the control means 10 controlling each controlled object configuration.

[0058] In this drying system 1, a frozen material F is produced as a preparation step before starting the drying process. In the production of the frozen material F, a brine liquid is supplied from the inlet 215 of the container body 21 to the container body 21, the inside of which is empty. Then, when the container body 21 is sealed, the control means 10 is made to start the preparation step. The control means 10 opens the cooling refrigerant supply valve 633 and operates the common refrigerator 6 and the cooling water pump 72. The control means 10 also controls the heat medium temperature adjustment unit 3 to open the cooling flow rate adjustment valve 33 to start driving the heat medium pump 31, close the waste heat supply valve 381, and open the waste heat bypass valve 382. Thereafter, the heat medium is cooled by the heat medium temperature adjustment unit 3 to a desired cooling temperature (for example, -30°C) that is equal to or lower than the freezing point of the dispersion liquid, while measuring the temperature of the brine liquid by the container thermometer 211. The control means 10 controls the heat medium heater 36 not to heat the heat medium until the cooling temperature is reached.

[0059] When the brine reaches a desired cooling temperature, the dispersion is poured into the container body 21 and rapidly frozen by immersion in the brine, thereby producing a frozen product F in which the dispersion is frozen. In this embodiment, an example is described in which a dispersion using water as a liquid component is used, but a dispersion using a liquid component other than water may be used. In addition, the dispersion is pre-frozen in advance and crushed to a degree that allows it to pass through the inlet 215, and a plurality of processed material chunks may be used as the frozen product F. When cooling the brine, the control means 10 also starts driving the stirring means 22 to rotate the spiral ribbon 221. This stirs the brine and the entire brine is cooled evenly. Then, the dispersion dropped into the brine is divided by the rotation of the spiral ribbon 221 to become a frozen product F consisting of a number of processed material chunks. When the frozen product F is obtained, only the brine is discharged from the brine outlet 212 provided in the container body 21. As a result, the frozen product F remains in the container body 21. Thereafter, the control means 10 opens the trap refrigerant supply valve 634 to circulate the refrigerant between the cold trap 5 and the common refrigerator 6 to lower the temperature of the cold trap 5 to -40°C. In addition, the control means 10 closes the cooling flow rate control valve 33 to start heating by the heat medium heater 36 to adjust the heating temperature and control the temperature of the heat medium to -20°C, which is a temperature below the eutectic point of the frozen object F. Furthermore, the control means 10 controls the spiral ribbon 221 to rotate at 10 rotations per minute. In the case where the basic minimum rotation speed of the spiral ribbon 221 is 10 rotations per minute, it is preferable that the maximum rotation speed that can be adjusted depending on the situation is 15 rotations per minute. The rotation speed set in this preparation process becomes the minimum rotation speed of the spiral ribbon 221 in the drying process. Then, the control means 10 adjusts the rotation of the spiral ribbon 221 to the minimum rotation speed or a higher rotation speed depending on the progress of the drying process. Instead of changing the rotation speed, intermittent stirring may be performed by repeatedly rotating and stopping the spiral ribbon 221. In this case, the control means 10 controls the time allocation between the driving time and the driving stop time of the stirring means 22 instead of the rotation speed.The temperature of the heat medium, the number of revolutions of the spiral ribbon 221, or the intermittent time distribution of the spiral ribbon 221 in the case of intermittent stirring, are set by the operator selecting a value that does not reliably melt the frozen material F according to the type of the object to be processed, the type of liquid component of the dispersion, or the proportions of the container body 21, and inputting it into the control means 10, and can be changed appropriately by the operator. In addition, by using a means that can automatically recognize the input conditions, it is possible to perform the preparation process in an automatic operation. By executing the above preparation process, preparation for starting the drying process is completed. Note that the method of generating the frozen material F using a brine solution is only one example, and there are various other preliminary freezing methods, such as a freezing method in which the dispersion liquid is sprayed under vacuum, and a freezing method in which the jacket 23 is heated to around 0°C to make the inside of the container body 21 less than 600 PaA and self-freeze it, and any of these methods may be used to generate the frozen material F.

[0060] FIG. 3 is a flowchart showing control in the drying process of the drying system 1 shown in FIG.

[0061] When the drying process is started, the control means 10 drives the vacuum pump 4 while maintaining the temperature of the heat medium, the temperature in the cold trap 5, and the rotation speed of the spiral ribbon 221 at the values ​​set in the preparation process. The pressure in the container body 21 is reduced to about 13 Pa or more and 120 Pa or less by driving the vacuum pump 4. During the drying process, the control means 10 controls the opening of the pressure regulating valve 42, so that the pressure in the container body 21 and the like is maintained at about 13 Pa or more and 120 Pa or less. When the pressure in the container body 21 decreases to 13 Pa or more and 120 Pa or less, for example, about 110 Pa, and further receives frictional heat from the spiral ribbon 221 and the container body 21 or heat from the heat medium in the jacket 23, moisture, which is a liquid component of the frozen object F that has been solidified, sublimes and begins to generate steam. Most of the steam generated during this drying process is frozen by the cold trap 5 on the way to the vacuum pump 4 and collected as ice (solid). The process in which this drying process is performed corresponds to an example of a collection process. In addition, there may be a small amount of brine liquid remaining in the container body 21 that was not completely drained during the preparation process. In such a case, the gas generated in the container body 21 may contain evaporated brine liquid, but this is an extremely small amount and usually does not pose a problem.

[0062] The control means 10 periodically repeats the processing of steps S11 to S26 shown in FIG. 3 at a predetermined time interval (for example, every 10 minutes) until the drying process is completed. Hereinafter, each of these periodically repeated processes may be referred to as a periodic process. The control means 10 obtains temperature data of the frozen object F at the start of each periodic process from the container thermometer 211, and determines whether the temperature of the frozen object F is equal to or lower than a reference temperature (step S11). The reference temperature is the temperature (eutectic point) at which the frozen object F begins to melt under the pressure inside the container body 21, or a temperature slightly lower than that temperature. For example, this reference temperature is −15° C. at the beginning of the drying process, and is gradually increased (raised) according to the elapsed time from the start of the drying process to finally reach 20° C.

[0063] If the temperature of the frozen object F is equal to or lower than the reference temperature (YES in step S11), the control means 10 judges whether the mass measured by the load cell 56 has changed from the previous mass stored in the memory unit 102 (step S12). This change in mass is a change caused by the steam collected as ice by freezing in the cold trap 5 during the period from the start of the previous regular processing to the start of the current regular processing, and is an increasing change. Therefore, the changed mass corresponds to the mass of the steam collected in the most recent regular processing, and is calculated by subtracting the previous mass stored in the memory unit 102 from the mass measured this time by the load cell 56. Hereinafter, this changed mass may be referred to as the collected mass. The existence of the collected mass indicates that the moisture contained in the frozen object F has sublimated and the drying process has progressed smoothly. That is, the control means 10 of this embodiment monitors the ice collection status by monitoring the change in the mass of ice measured by the load cell 56. By monitoring this collection status, the drying status of the frozen object F can be grasped. This step S12 corresponds to an example of a monitoring step. Note that in the first regular process, the previous mass information is not stored in the storage unit 102, so this step S12 becomes NO.

[0064] If there is a change in the mass of ice collected in the cold trap 5 (YES in step S12), the control means 10 judges whether the temperature of the heat medium supplied to the jacket 23 is less than the maximum temperature (step S13). This maximum temperature is, for example, 20°C. The maximum temperature is set by an operator selecting and inputting into the control means 10 a value according to the type of material to be treated and the type of liquid component of the dispersion, and can be changed as appropriate by the operator. On the other hand, if there is no change in the mass of ice collected in the cold trap 5 (NO in step S12), the process proceeds to step S24.

[0065] If the temperature of the heat medium supplied to the jacket 23 is less than the maximum temperature (YES in step S13), the temperature of the heat medium supplied to the jacket 23 is increased by 3° C. (step S14). That is, when the control means 10 judges in step S12 that the drying of the frozen object F is proceeding smoothly and in step S13 that there is still room for increasing the temperature of the heat medium, the temperature of the heat medium is increased to increase the amount of heat supplied to the frozen object F, thereby increasing the drying speed. The temperature to be increased to in step S14 is set by the operator by selecting and inputting it into the control means 10, and can be changed as appropriate by the operator, but is preferably 3° C. or more and 10° C. or less. Note that if an increase of 3° C. would cause the temperature of the heat medium to exceed the maximum temperature, the temperature of the heat medium is increased only to the maximum temperature.

[0066] When the process of increasing the temperature of the heat medium in step S14 is completed or the temperature of the heat medium supplied to the jacket 23 is equal to or higher than the maximum temperature (NO in step S13), the control means 10 judges whether the rotation speed of the spiral ribbon 221 is less than the maximum rotation speed (step S15). If the rotation speed of the spiral ribbon 221 is less than the maximum rotation speed (YES in step S15), the rotation speed of the spiral ribbon 221 is increased by 4 rotations / min (step S16). That is, when it is judged in step S12 that the drying of the frozen object F is proceeding smoothly and in step S15 that there is still room for increasing the rotation speed of the spiral ribbon 221, the rotation speed of the spiral ribbon 221 is increased to move the frozen object F more, thereby increasing the drying speed. The rotation speed to be increased in step S15 is set by the operator selecting and inputting it into the control means 10, and can be appropriately changed by the operator. Note that, if the maximum rotation speed is exceeded by increasing the rotation speed by 4 rotations / min, the increase in the rotation speed is limited to the maximum rotation speed. This maximum rotation speed is set by the operator to about 4 to 10 times the minimum rotation speed (10 rotations / min). In this embodiment, the maximum rotation speed of the spiral ribbon 221 is set to 86 rotations / min. By increasing the rotation speed of the spiral ribbon 221, the frozen object F is lifted higher.

[0067] When the process of increasing the number of rotations of the spiral ribbon 221 in step S16 is completed or the number of rotations of the spiral ribbon 221 is equal to or greater than the maximum number of rotations (NO in step S15), the control means 10 judges whether the collected mass, which is the amount of change between the currently measured mass and the previous mass stored in the memory unit 102, is equal to or less than a first predetermined amount (step S17). The first predetermined amount is a value set by an operator selecting and inputting into the control means 10 according to the amount of dispersion liquid or the amount of frozen material F put into the container body 21. This first predetermined amount is set to the mass of steam generated from the frozen material F at the time interval of the regular processing when the drying process is at the end and most of the moisture contained in the frozen material F has disappeared. By setting in this manner, it is possible to judge whether the drying process is at the end when most of the moisture contained in the frozen material F has disappeared.

[0068] If the rotation speed of the spiral ribbon 221 is increased in the beginning or middle of the drying process, the frozen object F is likely to melt due to frictional heat between the spiral ribbon 221 and the frozen object F, frictional heat between the frozen object F and the inner surface of the container body 21, and frictional heat between the frozen objects F themselves. However, since the moisture content is reduced at the end of the drying process, the risk of melting is reduced even if the rotation speed of the spiral ribbon 221 is increased. For this reason, it is preferable to shorten the drying time by increasing the rotation speed of the spiral ribbon 221 at the end of the drying process. By shortening the drying time, not only can the production efficiency be improved, but also the energy required for drying can be reduced. Furthermore, since the rotation speed of the spiral ribbon 221 is increased, the frozen object F is raised to a higher position, so that the frozen object F comes into contact with the inner surface of the container body 21 even in the upper part of the container body 21, and the heat of the heat medium can be efficiently transferred to the frozen object F. Therefore, if the amount of change between the currently measured mass and the previous mass is equal to or less than the first predetermined amount (YES in step S17), the rotation speed of the spiral ribbon 221 is increased to the maximum rotation speed to increase the drying speed (step S18). On the other hand, if the amount of change between the currently measured mass and the previous mass exceeds the first predetermined amount (NO in step S17), the drying process is still in the early or middle stage, so the process proceeds to step S24 without executing step S18 and step S19 described later so as not to melt the frozen object F.

[0069] Furthermore, if the amount of change between the currently measured mass and the previous mass is equal to or less than the first predetermined amount (YES in step S17), the amount of vapor received by the cold trap 5 is extremely small, so the refrigerant passing through the cooling pipe 51 returns to the common refrigerator 6 without being heated. This makes it easy for the common refrigerator 6 to enter a low-pressure cut state. When the common refrigerator 6 enters a low-pressure cut state, the cooling function of the refrigerant in the common refrigerator 6 is temporarily stopped, and the pressure and temperature in the cold trap 5 increase, and when the cooling function of the common refrigerator 6 is resumed, the pressure and temperature in the cold trap 5 decrease. This is repeated. Depending on the pressure and temperature in the cold trap 5, the pressure and temperature in the container body 21, the upstream exhaust path 511, and the downstream exhaust path 512 also fluctuate, so it becomes difficult to judge the drying state and whether or not drying is completed based on these pressures and temperatures. In contrast, in this embodiment, step S19 is executed depending on the ice collection state in the cold trap 5 to warm the refrigerant in the heat medium cooler 35, thereby controlling the common refrigerator 6 not to enter a low pressure cut state.

[0070] Specifically, in step S19, the control means 10 controls the heat medium temperature adjustment unit 3 to open the cooling flow rate adjustment valve 33, open the waste heat supply valve 381, and close the waste heat bypass valve 382. As a result, the heat medium that flowed only to the heat medium heater 36 also flows to the heat medium cooler 35, and the heat medium is cooled by the heat medium cooler 35. On the other hand, the refrigerant is heated in the heat medium cooler 35 and expands or evaporates, increasing its pressure and flowing to the common refrigerator 6, so that the pressure of the refrigerant measured by the refrigerant pressure gauge 62 increases, and the low-pressure cut state can be avoided. In other words, by raising the temperature of the refrigerant in the heat medium cooler 35, the load on the common refrigerator 6 is increased, and the low-pressure cut state can be avoided. The control means 10 fully opens the cooling flow rate adjustment valve 33 in step S19, but may also control the cooling flow rate adjustment valve 33 to be opened slightly when the collected mass becomes smaller than a predetermined amount in step S12, and then to increase the opening of the cooling flow rate adjustment valve 33 as the collected mass decreases.

[0071] Furthermore, by opening the waste heat supply valve 381 and closing the waste heat bypass valve 382, ​​the heat medium cooled in the heat medium cooler 35 and the cooling water heated in the common refrigerator 6 are heat exchanged in the heat exchanger 38. As a result, the heat medium is heated, and therefore less energy is required to heat the heat medium to a set temperature in the heat medium heater 36. Furthermore, as the cooling water is cooled in the heat exchanger 38, even colder cooling water can be obtained in the heat exchanger 7. As a result, the energy consumed in the drying system 1 can be reduced. After the above step S19 is completed, proceed to step S24.

[0072] If the temperature of the frozen material F exceeds the reference temperature in step S11 described above (NO in step S11), there is a risk that the frozen material F will melt if left as is. Therefore, the control means 10 sets the temperature of the heat medium supplied to the jacket 23 to a lowering temperature that is equal to or lower than the eutectic point of the frozen material F (step S21). This reduces the drying speed of the frozen material F, and suppresses melting of the frozen material F. This lowering temperature is, for example, -5°C. The lowering temperature is set by the operator selecting it according to the type of the material to be treated and the type of liquid component of the dispersion liquid, and inputting it into the control means 10, and can be changed as appropriate by the operator.

[0073] Following the start of the temperature change of the heat medium in step S21, the control means 10 judges whether the rotation speed of the spiral ribbon 221 exceeds a predetermined rotation speed (step S22). This predetermined rotation speed is set to 10 rotations / min, which is the minimum rotation speed. However, this predetermined rotation speed can be changed appropriately by the operator. If the rotation speed of the spiral ribbon 221 exceeds the predetermined rotation speed (YES in step S22), the control means 10 reduces the rotation speed of the spiral ribbon 221 to the minimum rotation speed (step S23). This reduces the drying speed of the frozen object F, and further suppresses the melting of the frozen object F. When the process of step S23 is completed or the rotation speed of the spiral ribbon 221 does not exceed the predetermined rotation speed (NO in step S22), the process proceeds to step S24.

[0074] In step S24, the mass information obtained from the load cell 56 in the current periodic process is stored in the storage unit 102. Here, when step S24 is executed via steps S21 to S23, there is no mass information in the current periodic process, so the previous mass information is stored in the storage unit 102 as the current mass information. When step S24 is executed via steps S21 to S23, mass information may be obtained from the load cell 56 in step S24 and stored in the storage unit 102. The mass data stored in the storage unit 102 may be overwritten for each drying process, but it is preferable to leave all data during the drying process or data for multiple periodic processes as history data in the storage unit 102 together with data measured by each instrument. These data can be used when verifying the setting values ​​set by the operator in the drying process. After storing the mass information, the control means 10 judges whether a predetermined time has elapsed since the start of the current periodic process (step S25). Then, it waits until the predetermined time has elapsed (NO in step S25). This predetermined time is 10 minutes, which is the time interval for regular processing. Note that the predetermined time in step S25 can be changed as appropriate by an operator, and by changing this predetermined time, the time interval for regular processing can be changed arbitrarily.

[0075] When a predetermined time has elapsed (YES in step S25), the control means 10 judges whether the collected mass is zero, the temperature of the frozen material F measured by the container thermometer 211 is the same as the temperature of the heat medium measured by the heat medium thermometer 362, and the temperature of the frozen material F has not changed for the past 10 minutes (step S26). If the collected mass is zero and the temperature of the frozen material F is the same as the heat medium and has not changed (YES in step S26), the drying is complete and the drying process is terminated. On the other hand, if there is a collected mass, if the temperature of the frozen material F is different from the temperature of the heat medium or if the temperature of the frozen material F has changed (NO in step S26), the process returns to step S11 and starts the next periodic process.

[0076] According to the drying system 1 and the drying method of this embodiment, the ice collection state in the cold trap 5 is basically equal to the steam generation state in the container body 21, so the drying state of the frozen object F can be grasped by monitoring the collection state. That is, the drying state of the frozen object F is determined by the amount of liquid components contained in the frozen object F, and when the amount of the liquid components decreases, the total amount of ice collected in the cold trap 5 increases accordingly, so the amount of liquid components contained in the frozen object F and the total amount of ice collected in the cold trap 5 are inversely proportional to each other. On the other hand, when the amount of liquid components contained in the frozen object F decreases, the amount of steam generated decreases, so the collected mass, which is the increase in ice per unit time in the cold trap 5, also decreases, so that they are in a proportional relationship. In this embodiment, the collection state is monitored by determining whether or not there is a change in the mass of ice and the collected mass, and the progress of the drying, the end of the drying process, and the completion of the drying process are grasped from the collection state. And, the control means 10 appropriately adjusts the amount of heat supplied from the heat medium to the frozen object F according to the ice collection state in the cold trap 5, so the drying time of the frozen object F can be shortened. And by shortening the drying time, it is possible to reduce the energy required for drying. Furthermore, since the speed at which the frozen material F is moved is increased toward the end of the drying process, this also shortens the drying time of the frozen material F and reduces the energy required for drying.

[0077] Next, a modified example of this embodiment will be described. In the following description, components having the same names as components described above will be assigned the same reference numerals as those used above, and duplicate descriptions will be omitted.

[0078] FIG. 4(a) is a simplified cross-sectional view showing a schematic diagram of the cold trap 5 in the drying system 1 of the first modified example. As shown in FIG. 4(a), the drying system 1 of the first modification is different from the previous embodiment in that the cold trap 5 is not provided with a load cell 56, but is provided with a laser distance meter 57 instead. In addition, a transparent glass window is formed in the housing of the cold trap 5 at a portion facing the laser distance meter 57. This glass window is made of sapphire glass, but may be made of other materials as long as it is transparent and does not easily cloud. In FIG. 4(a), the laser light emitted by the laser distance meter 57 and the laser light reflected and returning to the laser distance meter 57 are indicated by hollow triangular arrows in a two-dot chain line. This laser light is emitted toward the cooling tube 51 in the cold trap 5. The steam collected by the cold trap 5 turns into ice and adheres to the cooling tube 51 and is layered thereon, so the distance measured by the laser distance meter 57 is longest when no ice is attached to the cooling tube 51, and changes to become shorter as the thickness of the ice attached to the cooling tube 51 increases. Therefore, the change in distance from the distance when no ice is attached is the thickness of the ice attached to the cooling pipe 51.

[0079] FIG. 5 is a flowchart similar to FIG. 3, illustrating control in the drying process of the drying system 1 of the first modified example.

[0080] The drying system 1 and the drying method of the first modification are different from the previous embodiment in that, instead of monitoring the change in the mass of ice captured by the cold trap 5, the system monitors the change in the thickness of ice captured by the cold trap 5 and attached to the cooling tube 51, as shown in FIG. 5. In step S121, which replaces step S12, the control means 10 causes the laser distance meter 57 to perform measurement and determines whether the ice thickness calculated from the measured distance has changed from the previous ice thickness stored in the memory unit 102. This change in thickness is a change caused by steam captured as ice by adhering to the cooling tube 51 in the cold trap 5 during the period from the start of the previous regular processing to the start of the current regular processing, and is a change in the increasing direction. The increase in thickness indicates that the moisture contained in the frozen object F has sublimated and the drying process is progressing smoothly. That is, in this first modification, the ice collection status is monitored by monitoring the change in the ice thickness. Then, the drying status of the frozen object F is grasped from the change in the ice thickness. This step S121 corresponds to an example of a monitoring process. In the first periodic process, the previous thickness information is not stored in the storage unit 102, so that the result in step S121 is NO.

[0081] In step S171, which replaces step S17, the control means 10 judges whether the amount of change between the currently measured thickness and the previous thickness stored in the memory unit 102 is equal to or less than a first predetermined amount. The first predetermined amount is a value set by an operator selecting and inputting it into the control means 10. This first predetermined amount is set as the thickness of ice collected by the cold trap 5 during the time interval of the regular processing when the drying process reaches the end and the moisture contained in the frozen object F has almost disappeared. By setting it in this manner, it is judged that most of the moisture contained in the frozen object F has disappeared and the drying process is in the final stage.

[0082] In step S241 instead of step S24, control means 10 stores ice thickness information calculated from the measurement results of laser range finder 57 in the current regular processing in memory unit 102. Here, when step S241 is executed via steps S21 to S23, there is no thickness information for the current regular processing, so the previous thickness information is stored as the current thickness information in memory unit 102. Note that when step S241 is executed via steps S21 to S23, it is also possible to cause laser range finder 57 to perform measurement in step S241, calculate the thickness from the measurement results, and store it in memory unit 102.

[0083] In step S261, which replaces step S26, the control means 10 judges whether the amount of change between the thickness measured in the current periodic process and the previous thickness stored in the memory unit 102 at the start of the current periodic process is zero, and the temperature of the frozen object F measured by the container thermometer 211 is the same as the temperature of the heat medium measured by the heat medium thermometer 362, and further whether the temperature of the frozen object F has not changed for the past 10 minutes. If there is no change in thickness and the temperature of the frozen object F is the same as the heat medium and stable (YES in step S261), the drying process is terminated. If there is a change in thickness, if the temperature of the frozen object F is different from the temperature of the heat medium, or if the temperature of the frozen object F is fluctuating (NO in step S261), the process returns to step S11 and starts the next periodic process.

[0084] As the moisture content of the frozen material F decreases, the amount of steam generated in the container body 21 decreases proportionally, and the change per unit time in the thickness of the ice adhering to the cooling pipe 51 decreases, so the drying system 1 and drying method of the first modified example described above achieve the same effects as the previous embodiment.

[0085] FIG. 4(b) is a simplified cross-sectional view that illustrates a schematic diagram of the cold trap 5 in the drying system 1 of the second modified example.

[0086] As shown in FIG. 4(b), the drying system 1 of the second modified example is different from the previous embodiment in that the cold trap 5 is not provided with a load cell 56, but instead is provided with a 3D scanner 58. In addition, a transparent glass window is formed in the housing of the cold trap 5 at a portion facing the 3D scanner 58. This glass window is made of sapphire glass, but may be made of other materials as long as it is transparent and does not easily cloud. This 3D scanner 58 scans the shape of the ice attached to the cooling pipe 51 to generate three-dimensional data.

[0087] FIG. 6 is a flowchart similar to FIG. 3, illustrating control in the drying process of the drying system 1 of the second modified example.

[0088] The drying system 1 and the drying method of the second modified example are different from the previous embodiment in that, as shown in FIG. 6, the change in the shape of the ice captured by the cold trap 5 is monitored instead of the change in the mass of the ice captured by the cold trap 5. In step S122, which replaces step S12, the control means 10 determines whether the shape of the ice obtained by making the 3D scanner 58 execute a scan has changed from the previous shape of the ice stored in the memory unit 102. This change in shape is a change during the period from the start of the previous regular processing to the start of the current regular processing, and is a change in the direction in which the thickness of the ice, the volume of the ice, and the area of ​​the ice in the cross section cut in the radial direction of the cooling tube 51 increase. The change in shape indicates that the moisture contained in the frozen object F has sublimated and the drying process is progressing smoothly. That is, in this second modified example, the ice capture status is monitored by monitoring the change in the shape of the captured ice. Then, the drying status of the frozen object F is grasped from the change in shape. This step S122 corresponds to an example of a monitoring process. In the first periodic process, the previous shape information is not stored in the storage unit 102, so that the result in step S122 is NO.

[0089] In step S172, which replaces step S17, the control means 10 judges whether the increase in volume between the shape scanned this time and the shape scanned previously and stored in the memory unit 102 is equal to or less than a first predetermined amount. The cross-sectional area of ​​the ice or the thickness of the ice may be used instead of the volume of the ice to make the judgment. The first predetermined amount is a value set by an operator selecting and inputting it into the control means 10. This first predetermined amount is set as the volume of ice collected by the cold trap 5 during the time interval of the regular processing when the drying process reaches the end and the moisture contained in the frozen object F has almost disappeared. By setting it in this manner, it is judged that most of the moisture contained in the frozen object F has disappeared and the drying process is in the final stage.

[0090] In step S242 instead of step S24, control means 10 stores information on the shape of the ice scanned by 3D scanner 58 in the current regular processing in storage unit 102. Here, when step S242 is executed via steps S21 to S23, there is no shape information for the current regular processing, so information on the previous shape is stored as information on the current shape in storage unit 102. Note that when step S242 is executed via steps S21 to S23, the shape of the ice scanned by 3D scanner 58 in step S242 may be obtained and stored in storage unit 102.

[0091] In step S262 instead of step S26, the control means 10 judges whether or not the amount of change between the shape scanned in the current regular processing and the previous shape stored in the memory unit 102 at the start of the current regular processing is zero, and the temperature of the frozen object F measured by the container thermometer 211 is the same as the temperature of the heat medium measured by the heat medium thermometer 362, and further whether or not the temperature of the frozen object F has not changed for the past 10 minutes. If there is no change in the shape and the temperature of the frozen object F is the same as the heat medium and stable (YES in step S262), the drying process is terminated. If there is a change in the shape, if the temperature of the frozen object F is different from the temperature of the heat medium, or if the temperature of the frozen object F is fluctuating (NO in step S262), the process returns to step S11 and starts the next regular processing.

[0092] As the moisture content of the frozen material F decreases, the amount of steam generated in the container body 21 decreases proportionally, and the change per unit time in the shape of the ice adhering to the cooling pipe 51 decreases, so the drying system 1 and drying method of the second modified example described above achieve the same effects as the previous embodiment.

[0093] FIG. 7 is a system diagram similar to FIG. 1, showing a drying system according to a third modified example.

[0094] As shown in FIG. 7, the drying system 1 of the third modified example is different from the previous embodiment in that two cold traps 5 are provided. Hereinafter, in the description of the drying system 1 of the third modified example, the cold trap 5 depicted on the lower side of FIG. 7 may be referred to as the first cold trap 5A, and the cold trap 5 depicted on the upper side of FIG. 7 may be referred to as the second cold trap 5B. The upstream exhaust path 511 branches into a first upstream exhaust path 5111 connected to the first cold trap 5A and a second upstream exhaust path 5112 connected to the second cold trap 5B. The first upstream exhaust path 5111 is provided with a first exhaust path valve 5113. The second upstream exhaust path 5112 is provided with a second exhaust path valve 5114. The first exhaust path valve 5113 and the second exhaust path valve 5114 are controlled by the control means 10 so that, in principle, when one of them is open, the other is closed. In the preparation step, the control means 10 opens one of the first exhaust valve 5113 and the second exhaust valve 5114 and closes the other, and switches between opening and closing these valves for each periodic process. This causes the steam discharged from the vessel body 21 to flow into either the first cold trap 5A or the second cold trap 5B.

[0095] The downstream exhaust path 512 is connected to the vacuum pump 4 at the junction of a first downstream exhaust path 5121 connected to the first cold trap 5A and a second downstream exhaust path 5122 connected to the second cold trap 5B. A third exhaust path valve 5123 is provided in the first downstream exhaust path 5121. A fourth exhaust path valve 5124 is provided in the second downstream exhaust path 5122. The third exhaust path valve 5123 is controlled by the control means 10 (see FIG. 2) in synchronization with the first exhaust path valve 5113 so as to be in the same open / closed state as the first exhaust path valve 5113. The fourth exhaust path valve 5124 is controlled by the control means 10 in synchronization with the second exhaust path valve 5114 so as to be in the same open / closed state as the second exhaust path valve 5114. The first exhaust passage valve 5113, the second exhaust passage valve 5114, the third exhaust passage valve 5123, the fourth exhaust passage valve 5124, and the control means 10 (see FIG. 2) correspond to an example of a switching means. In the downstream exhaust passage 512, the joining portion of the first downstream exhaust passage 5121 and the second downstream exhaust passage 5122, the connection portion of the intake passage 41, and the measurement position of the oxygen concentration meter 44 are arranged in this order from the upstream in the gas flow.

[0096] The trap refrigerant supply passage 632 branches into a first trap refrigerant supply passage 6321 leading to the cooling pipe 51 for cooling the inside of the first cold trap 5A and a second trap refrigerant supply passage 6322 leading to the cooling pipe 51 for cooling the inside of the second cold trap 5B. The first trap refrigerant supply passage 6321 is provided with a first trap refrigerant supply valve 6341. The second trap refrigerant supply passage 6322 is provided with a second trap refrigerant supply valve 6342. The first trap refrigerant supply valve 6341 and the second trap refrigerant supply valve 6342 are controlled by the control means 10 (see FIG. 2) to open and close simultaneously in principle. That is, like the trap refrigerant supply valve 634 in the previous embodiment, the first trap refrigerant supply valve 6341 and the second trap refrigerant supply valve 6342 are both opened in the preparation step. However, since the first cold trap 5A and the second cold trap 5B are used alternately for each periodic process, the valve leading to the cooling pipe 51 of the cold trap 5 that is not being used may be controlled to be closed for each periodic process.

[0097] The trap refrigerant recovery passage 642 is joined by a first trap refrigerant recovery passage 6421 through which the refrigerant returns from the cooling pipe 51 that cools the inside of the first cold trap 5A and a second trap refrigerant recovery passage 6422 through which the refrigerant returns from the cooling pipe 51 that cools the inside of the second cold trap 5B. The first trap refrigerant recovery passage 6421 is provided with a first trap refrigerant recovery valve 6423. The second trap refrigerant recovery passage 6422 is provided with a second trap refrigerant recovery valve 6424. The first trap refrigerant recovery valve 6423 is controlled by the control means 10 (see FIG. 2) in synchronization with the first trap refrigerant supply valve 6341 so as to be in the same open / closed state as the first trap refrigerant supply valve 6341. The second trap refrigerant recovery valve 6424 is controlled by the control means 10 in synchronization with the second trap refrigerant supply valve 6342 so as to be in the same open / closed state as the second trap refrigerant supply valve 6342.

[0098] The control in the drying process of the drying system 1 of the third modified example differs from the previous embodiment in that the switching control of the cold trap 5 is added in step S12 shown in FIG. 3 and that the mass information stored in the memory unit 102 in step S24 is held for up to the periodic process before last. Other than that, the control is the same as the previous embodiment, so the differences from the previous embodiment will be mainly described with reference to FIG. 3. In step S12, the control means 10 closes the open valve of the first exhaust passage valve 5113 and the second exhaust passage valve 5114 and opens the closed valve to switch the cold trap 5 that receives steam. After that, the control means 10 obtains information on the mass of ice measured by the load cell 56 of the cold trap 5 that received steam through the valve that was open before the switching. Then, it is determined whether the mass measured this time has changed from the mass measured by the same cold trap 5 two times before last.

[0099] Instead of comparing the mass of ice in step S12, the ice in the cold trap 5 that received steam through the valve that was open before the switching may be melted to water, and the mass of the water may be measured. In this case, the mass of the water is the mass of the steam collected in the cold trap 5 in the most recent regular processing, and if the mass of the water is not zero (if water is present), step S12 will be YES. Here, the water in the cold trap 5 may be drained through a drain valve provided in the cold trap 5 and placed in a tray, and the mass may be measured. In the configuration for measuring the mass of the melted water, in step S17, it is determined whether the mass of the water is equal to or less than a first predetermined amount. In addition, in step S26, it is determined whether the mass of the water measured this time is zero, instead of whether the mass has changed. In this configuration for measuring the mass of the melted water, water is drained from the cold trap 5 for each regular processing, so there is no need to subtract the previous mass to determine the change in mass, and step 24 may be omitted.

[0100] The drying system 1 and the drying method of the third modified example described above provide the same effects as those of the previous embodiment. Note that three or more cold traps 5 may be provided and used by switching between them one by one. When three or more cold traps 5 are provided, the same effects as those of the previous embodiment are provided.

[0101] FIG. 8 is a diagram showing a heat medium temperature adjusting section 3 in a drying system 1 according to the fourth modified example.

[0102] As shown in FIG. 8, the heat medium temperature adjustment unit 3 of the drying system 1 of the fourth modification is different from the previous embodiment in that the heat medium that has passed through the heat medium cooler 35 is supplied to the jacket 23 (see FIG. 1) through the heat medium supply path 231 without returning to the heat medium tank 37. In the drying system 1 of the fourth modification, when it is desired to cool the heat medium or to heat the refrigerant, the cooling flow rate adjustment valve 33 is opened to pass the heat medium cooler 35. The heat medium that is diverted at the diverter 32 and passes through the heat medium heater 36 is sent to the heat medium supply path 231 without heating if it is desired to cool the heat medium, and when it is desired to heat the refrigerant, the heat medium is heated by the heat medium heater 36 as necessary to adjust the temperature to a desired value and sent to the heat medium supply path 231. When neither cooling nor heating of the heat medium nor heating of the refrigerant is required, the cooling flow rate adjustment valve 33 is closed, and the heat medium is passed through the heat medium heater 36 without being heated and sent to the heat medium supply path 231.

[0103] The drying system 1 and the drying method of the fourth modified example described above also have the same effects as those of the previous embodiment.

[0104] FIG. 9 is a diagram showing a heat medium temperature adjusting section 3 in a drying system 1 according to the fifth modified example.

[0105] As shown in Fig. 9, the heat medium temperature adjustment unit 3 of the drying system 1 of the fifth modified example differs from the previous embodiment in that the heat medium that has passed through the heat medium cooler 35 flows toward the heat medium heater 36 and that a first flow rate adjustment valve 341, which is an electric valve, is provided in the heat medium flow path from the heat medium pump 31 toward the heat medium heater 36 instead of the constant flow rate valve 34. Also, it differs from the previous embodiment in that a detour 363 through which the heat medium flows is formed to bypass the heat medium heater 36, a second flow rate adjustment valve 342, which is an electric valve, is provided in the detour 363, and a third flow rate adjustment valve 343, which is an electric valve, is provided between the branch point to the detour 363 and the heat medium heater 36. The openings of the first flow rate adjustment valve 341, the second flow rate adjustment valve 342, and the third flow rate adjustment valve 343 are controlled by the control means 10 (see Fig. 2). The first flow rate control valve 341, the second flow rate control valve 342, and the third flow rate control valve 343 can be closed to set the flow rate to zero. The heat medium thermometer 362 is disposed downstream of the junction where the flow path of the heat medium passing through the heat medium heater 36 and the bypass 363 join. This allows the heat medium thermometer 362 to measure the temperature of the heat medium that has passed through the heat medium heater 36, the temperature of the heat medium that has passed through the bypass 363, and the temperature of the heat medium that is a mixture of these. When it is desired to cool the heat medium in the drying system 1 of the fifth modified example, the cooling flow rate control valve 33 and the second flow rate control valve 342 are opened, and the first flow rate control valve 341 and the third flow rate control valve 343 are closed. This allows the heat medium to pass through the heat medium cooler 35 to be cooled, and to pass through the bypass 363 without passing through the heat medium heater 36. When it is desired to raise the temperature of the refrigerant, the cooling flow rate adjustment valve 33 and the third flow rate adjustment valve 343 are opened, and the first flow rate adjustment valve 341 and the second flow rate adjustment valve 342 are closed. As a result, the heat medium passes through the heat medium cooler 35 and the heat medium heater 36, has its temperature adjusted, and is sent out to the heat medium supply path 231. On the other hand, when it is desired to heat the heat medium, the cooling flow rate adjustment valve 33 and the second flow rate adjustment valve 342 are closed, and the first flow rate adjustment valve 341 and the third flow rate adjustment valve 343 are opened. As a result, the heat medium is heated in the heat medium heater 36 without passing through the heat medium cooler 35.The openings of the cooling flow rate control valve 33, the first flow rate control valve 341, the second flow rate control valve 342, and the third flow rate control valve 343 may be adjusted to mix the heated heat medium and the cooled heat medium and send it to the heat medium supply path 231. When neither cooling nor heating of the heat medium nor heating of the refrigerant is required, the cooling flow rate control valve 33 and the third flow rate control valve 343 are closed, and the first flow rate control valve 341 and the second flow rate control valve 342 are opened to send the heat medium to the heat medium supply path 231 without cooling or heating.

[0106] Furthermore, the heat medium temperature adjustment section 3 in the drying system 1 of the fifth modified example is different from the previous embodiment in that a heat medium pressure gauge 311, a tank heat medium thermometer 312, a first bypass passage 391, a fourth flow rate control valve 392, a fifth flow rate control valve 393, a second bypass passage 395, a sixth flow rate control valve 396, and a seventh flow rate control valve 397 are provided. The heat medium pressure gauge 311 is disposed between the branch section 32 and the heat medium pump 31. The heat medium pressure gauge 311 is a pressure gauge that measures the pressure of the heat medium sent out from the heat medium pump 31. The tank heat medium thermometer 312 is a thermometer that measures the temperature of the heat medium going from the heat medium tank 37 to the heat medium pump 31. The pressure of the heat medium measured by the heat medium pressure gauge 311 and the temperature of the heat medium measured by the tank heat medium thermometer 312 are constantly transmitted to the control means 10 (see FIG. 2).

[0107] The first bypass path 391 is a heat medium flow path through which the heat medium diverted toward the heat medium cooler 35 at the diverting section 32 returns directly to the heat medium tank 37. The fourth flow control valve 392 is provided on this first bypass path 391. The fifth flow control valve 393 is an electric valve arranged between a diverting section 394 to the first bypass path 391 and the heat medium cooler 35. The opening degrees of these fourth flow control valve 392 and fifth flow control valve 393 are controlled by the control means 10 (see FIG. 2). The fourth flow control valve 392 and fifth flow control valve 393 can also be closed to set the respective flow rates to zero.

[0108] The second bypass path 395 is a heat medium flow path through which the heat medium that has passed through the heat medium cooler 35 flows, bypassing the heat exchanger 38. The sixth flow rate control valve 396 is provided in this second bypass path 395. The seventh flow rate control valve 397 is an electric valve that is arranged between a branch portion 398 to the second bypass path 395 and the heat exchanger 38. The opening degrees of these sixth flow rate control valve 396 and seventh flow rate control valve 397 are controlled by the control means 10 (see FIG. 2). Note that the sixth flow rate control valve 396 and seventh flow rate control valve 397 can also be closed to set the respective flow rates to zero.

[0109] The heat medium pump 31 generates heat when driven, and the temperature of the heat medium discharged from the heat medium pump 31 increases due to this heat. If the output of the heat medium pump 31 is increased, the temperature of the heat medium that increases in the heat medium pump 31 increases in proportion to the output. The output here refers to the rotation speed of the heat medium pump 31. In addition, by increasing the output of the heat medium pump 31, the flow rate of the heat medium being pumped increases, but since the valve opening of the cooling flow rate control valve 33 and the first flow rate control valve 341 in the subsequent stage is narrowed to achieve a desired flow rate, the kinetic energy of the heat medium is converted into thermal energy, and the temperature of the heat medium further increases. Therefore, in the drying system 1 of the fifth modified example, when the temperature of the heat medium measured by the tank heat medium thermometer 312 is too low and it is expected that the effect of increasing the temperature of the refrigerant in the heat medium cooler 35 is insufficient, the output of the heat medium pump 31 is increased to increase the temperature of the heat medium in the heat medium pump 31 and send it to the heat medium cooler 35. At that time, the cooling flow rate adjustment valve 33 and the first flow rate adjustment valve 341 are also controlled by the control means 10 (see FIG. 2) in accordance with the pressure of the heat medium measured by the heat medium pressure gauge 311 so that the heat medium flows at a desired flow rate.

[0110] The drying system 1 and the drying method of the fifth modified example described above have the same effects as those of the previous embodiment. In addition, the control means 10 controls the opening degree of each valve provided in the heat medium temperature adjustment unit 3, thereby enabling the heat medium temperature adjustment unit 3 to adjust the temperatures of the heat medium and the refrigerant in a wide adjustment range.

[0111] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the claims. For example, in the above-mentioned embodiment, the drying speed of the frozen material F is adjusted by adjusting the temperature of the heat medium supplied to the jacket 23 and the rotation speed of the spiral ribbon 221, but only one of these may be adjusted and the other may be kept constant. In addition, the spiral ribbon 221 is always rotating, but it may be configured to rotate and stop repeatedly, and the frequency of moving the frozen material F, which is the ratio of the driving time and the driving stop time of the stirring means 22, may be adjusted instead of the rotation speed of the spiral ribbon 221, or both the rotation speed of the spiral ribbon 221 and the frequency of moving the frozen material F may be adjusted. Furthermore, instead of adjusting the temperature of the heat medium supplied to the jacket 23, or in addition to adjusting the temperature of the heat medium, the flow rate of the heat medium supplied to the jacket 23 may be adjusted. Furthermore, instead of the spiral ribbon 221, a stirring blade consisting of a blade-shaped paddle member having a flat surface in the vertical direction at the tip part of a metal arm radially protruding from the stirring drive shaft 222 may be provided in the container body 21 to move the frozen material F.

[0112] In addition, instead of the stirring means 22, the entire container body 21 may be supported by a tubular shaft so that it can rotate or swing freely, and the container body 21 may be rotated or swinged by a motor, so that the frozen object F is moved within the container body 21. In such a configuration, the shaft supporting the container body 21, the container body 21, and the motor rotating or swinging the container body 21 correspond to an example of a frozen object operating unit. In that case, instead of adjusting the number of rotations of the spiral ribbon 221, it is preferable to adjust the frequency of rotation or swing of the container body 21. However, the number of rotations or swing of the container body 21 may be adjusted by controlling the container body 21 to always rotate or swing.

[0113] Furthermore, instead of the common refrigerator 6 that cools both the heat medium cooler 35 and the cold trap 5, a dedicated refrigerator may be provided for each of the heat medium cooler 35 and the cold trap 5.

[0114] In addition, even if a constituent element is included only in the description of the embodiment and each modified example described above, that constituent element may be applied to the embodiment and each modified example. [Explanation of symbols]

[0115] 1 Drying System 3 Heat medium temperature adjustment section 5. Cold Trap 10. Control Means 21 Container body 22 Stirring means 56 Load Cell F Frozen material

Claims

1. A container body for storing a frozen object obtained by freezing the object to be processed; A drying means for drying the frozen object by sublimating a solidified liquid component contained in the frozen object stored in the container body into vapor; a cold trap that receives the vapor and freezes the vapor into a solid form for collection; and a monitoring means for monitoring a state of capture of the solid in the cold trap.

2. 2. The drying system of claim 1, wherein said monitoring means monitors a change in mass of said solids trapped in said cold trap.

3. the cold trap has a cooling tube to which the solid adheres; 2. The drying system according to claim 1, wherein said monitoring means monitors a change in thickness of said solid material adhering to said cooling pipe.

4. the cold trap has a cooling tube to which the solid adheres; 2. The drying system according to claim 1, wherein said monitoring means monitors changes in shape of said solid matter adhering to said cooling pipe.

5. A plurality of said cold traps; a switching means for switching the cold trap that receives the steam among the plurality of cold traps, 2. The drying system according to claim 1, wherein the monitoring means monitors the collection status by measuring a mass of the solids collected by the cold trap that had received the steam before the switching means switched the cold trap.

6. a jacket covering the outer periphery of the container body and through which a heat medium flows to supply heat to the frozen material contained in the container body; 6. The drying system according to claim 1, further comprising a control means for adjusting an amount of heat supplied from the heat medium to the frozen material in accordance with the collection state.

7. a frozen object operating unit that moves the frozen object stored in the container body within the container body; A drying system as described in any one of claims 1 to 5, characterized in that it is provided with a control means for adjusting at least one of the speed at which the frozen material is moved by the frozen material operating unit and the frequency at which the frozen material is moved depending on the collection situation.

8. A drying method for a drying system including a container body for storing a frozen material obtained by freezing an object to be processed, and a drying means for drying the frozen material by sublimating a solidified liquid component contained in the frozen material stored in the container body into vapor, the drying method comprising: a capture step of freezing the vapor to form a solid and capture it; and a monitoring step of monitoring a state of collection of the solid in the collection step.

Images