JP2008304171A - Dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dryer capable of setting a drying temperature below 30&deg;C. <P>SOLUTION: A drying sample is arranged in an atmosphere of a convection gas at a pressure below 0.1-0.5 atm, and dried at a drying temperature below 30&deg;C by this vacuum dryer as shown in Fig.1. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a drying apparatus with little quality change.

Conventional technology

Drying with little change in quality is performed by vacuum drying, freeze drying, or natural drying using winter cold wind. The drying temperature that determines the quality of the vacuum drying device or freeze drying device is a temperature determined by the relationship between the degree of vacuum and the boiling point of the evaporated substance (usually water). The energy of evaporation of the dry matter depends on the heat transfer energy from the tray on which the sample is loaded and the radiant heat from the container wall.

However, in the conventional method as described above, the heat supply rate to the dried product is low, and increasing the temperature of the tray in order to increase the heat supply rate has caused a great influence on the quality.

This invention makes it a subject to provide the method which can manufacture a high quality dried material in a short time and low cost in view of the above problems.

In the present invention, high-quality drying can be produced in a short time and at low cost, and vacuum cooling can be performed at low cost.

Although the drying temperature was set to 30 ° C. as a problem, this is a temporary target value, and the temperature of quality change differs depending on the sample, so it is not particularly fixed.

In the present invention, in addition to the shelf type which is dried by convection of air having a pressure of 0.1 to 0.5 atm or less, fluidized bed drying (FIG. 4), spray drying (FIG. 5), vibration drying, dry matter on the plate surface It can be applied to the method of adhering and drying, vacuum cooling, etc.

Means for solving the problem

In order to solve the above problems, the following several problems have been devised.

First, it was based on convection drying of vacuum air. Consider the conditions necessary for that.

First, the size of the blower is devised. There is some gas in the vacuum gas corresponding to the pressure. A method of moving the gas in mass is devised. The amount of gas transported by the blower depends on the blade size and the number of rotations. For example, a blower having a transport capacity of 100 kw at normal pressure is considered to have a capacity of 1 kw under a vacuum of 1/100. The type of blower is determined by the transport volume and transport resistance. The resistance is selected according to the required pressure such as propeller, sirocco, turbo, roots, piston. The amount of energy transport during drying is mass. The actual power required for the blower varies greatly depending on the efficiency due to the sliding of the blade surface. In this patent, the drying method is selected according to the method suitable for the degree of vacuum appropriate for the purpose of drying, the temperature of the dried product, the device structure, etc., the device components are selected, and the power is selected. The fluctuation range of power greatly exceeds the range controlled by the inverter. As shown in the claim, it is composed of 1/2 of the required power during operation under normal pressure, preferably 1/5 to 1/20, much less than the power required for operation under normal pressure. A blower was used.

Next, consider the saturated moisture content of air under vacuum. Non-Patent Document 1 (Chemical Engineering Handbook, May 10, 1968, revised edition 3rd edition issued, editor. Chemical Engineering Association of Japan, p34) "Saturation temperature of high-pressure air" shown in Fig. 1.28 The values of 20 ° C. obtained by extrapolating the diagram to the low-pressure conditions are 0.1, 0.2, 0.3 kg / cm ² , and the water contents are 0.2, 0.09, 0.06 kg / kg, respectively. is there. Compared with the fact that the moisture content of air at 20 ° C. at 1 atm is 0.015 kg / kg, the moisture transport amount of 1 kg of vacuum air is about 0.1, 0.2 and 0.3 kg / cm ² respectively. 1/13, 1/6, and 1/4 are possible. The effect of using this phenomenon for the transport phenomenon of dry air is very significant.
Chemical Engineering Handbook, 3rd edition, revised on May 10, 1968, editor. Japan Society for Chemical Engineering

The pressure of 0.2 kg / cm ² is in the range of the degree of vacuum that is easily possible with a water ring vacuum pump.

Next, consider the drying temperature at which the dried product is in a convection gas atmosphere. The ambient temperature of the dried product affects the energy transfer rate to the dried product, but not the temperature that directly affects the quality of the dried product. The quality of the dried product is the temperature at the site where moisture is evaporated. It was experimentally confirmed that these general theories in the drying phenomenon under normal pressure can be applied to the convection drying phenomenon of dilute air under vacuum.
In the method of the present invention, the dew point temperature of the convection gas indicates the drying temperature. The dew point in the method of this patent is the temperature of the cooling heat medium of the heat exchanger. When cooling with a cooling tower using outside air, the dew point is the temperature of the cooling water, and the temperature made with the refrigerator is the dew point temperature.

1. Select a blower that considers mass transport of air under vacuum,
2. Consider the pressure, temperature, moisture in the air under vacuum,
3. Considering that the quality of the dried product under vacuum is greatly affected by the temperature of the moisture location,
4). Considering many equipment costs such as the drying chamber, vacuum pump, heat supply, heat discharge, air flow, etc.
5. As a result of comprehensively considering the above items 1 to 4 and devising the best drying device, the indoor pressure of the drying device 1 shown in FIG. 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, A heat exchanger 5 that installs a blower 4 configured with a power of 1/2, preferably 1/5 to 1/10 of the power required when rotating under atmospheric pressure, and gives energy to the indoor gas of the drying apparatus 1. A heat source generator 6 that supplies a heat source to the heat exchanger 5, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, and a heat exchanger that converts the moisture of the indoor gas of the drying device 1 into liquid or ice. 7, a cooling device 8 that cools the energy obtained by the heat exchanger 7, a conduit 9 that maintains the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10 are used as a basic configuration. The basic idea of this patent can be applied to many drying methods. As an example, a shelf type, a flow type and a spray type are shown.

The humidity of the circulating gas was made possible by introducing a part of the circulating gas into the heat exchanger for collecting condensed water.

In drying under vacuum drying, it was confirmed that the temperature difference between the ambient temperature of the dried product and the dew point temperature affects the heat flow rate supplied to the sample.

  It dried using the apparatus shown in FIG. The configuration of FIG. 1 will be described. The drying chamber 1 is a container that can hold a vacuum. In the chamber, a blower 4 composed of a blower blade 2 and a power 3 that rotates the blower blade 2, and a heat exchanger 5 that gives energy to the indoor gas of the drying device 1, A boiler 6 for supplying steam to the heat exchanger 5, a heat exchanger 7 for condensing the water vapor generated by drying into liquid water, a device 8 for cooling the energy obtained in the heat exchanger 7, and a vacuum gas It comprises a duct 9 led out to the outdoors, a vacuum pump 10, a tray 14 on which a dried sample 13 is loaded, and guide plates 11 and 12 that circulate the room gas of the drying apparatus 1.

A supplementary description will be given of the configuration contents of FIG.
The tray 14 may be a wire mesh or a perforated plate on which a sample can be loaded and held, and it is not necessary to use a hot plate that guides vapor from a boiler for giving drying energy to the sample from the tray by a conduit or heating with a heater.

The gas flow 17 generated in the blower 4 becomes a gas flow 18 through the heat exchanger 5, passes through the sample 13 and becomes a gas flow 19, and a part of the gas flow 19 passes through a duct formed by the guide plates 11 and 12. Thus, a part of the gas flow 19 becomes a gas flow 16 passing through the heat exchanger 7, and the gas flows 15 and 16 merge to form a gas flow 17, which constitutes a gas circulation reaching the blower 4.
The same effect can be expected even if the gas flow direction of the drying apparatus of FIGS.

Conventionally, the drying temperature of vacuum drying has been discussed in terms of the boiling point of water, but since the drying temperature of the present invention is determined by the dew point temperature of the indoor circulation gas, the temperature around the dried product is, for example, 30 ° C. even if it is 60 ° C. Drying is possible.

Here, in the above sentence, the term “vacuum” is used. However, in general, this level of pressure is often expressed as “decompression”. However, since the vocabulary of vacuum or decompression expresses the same thing, this patent sentence expressed all the pressures lower than normal pressure in vacuum. The normal pressure was 1 atm and the absolute vacuum was 0 atm.

Since the heat supply to the dried sample depends on the energy provided by the convection from the circulating gas, in any drying of this patent apparatus, if the convection is stopped, the energy is not supplied and the drying does not proceed.

The heat supply to the sample is primarily governed by the temperature difference between the temperature on the enthalpy line of the circulating gas and the product temperature.

The drying according to the invention can also be applied to freeze-drying equipment. The drying temperature of lyophilization is the temperature at which ice evaporates, so the ice evaporation temperature of 0 ° C. is the dew point temperature, and lyophilization is possible by a convection gas drying method.

Furthermore, the device of the present invention can be applied to vacuum cooling. In the case of application to vacuum cooling, it is not necessary to supply heat from the boiler, and it is only necessary to place the sample in the circulating gas through the device 8 that cools the energy obtained by the heat exchanger 7.

Cooling with this device can be expected to have a greater economic effect on the device cost and operation cost than the vacuum cooling method.

Drying test results

As a result of performing a drying test with a carrot thickness of 2 cm and a radish thickness of 3 cm at a degree of vacuum of 0.2 atm and a temperature of 60 ° C., the drying temperature could be maintained at 25 to 28 ° C. A product without discoloration of the dried product was obtained.

This drying temperature course shows that it is dried at the dew point temperature, and the temperature does not differ depending on whether the water in the vegetable tissue is liquid or solid.

It is possible to dry vegetables with little change in target quality with a water-sealed vacuum pump.

All samples having an evaporating component as a sample to be dried are possible.

  Although it changes with areas and time, the cooling device 11 can be a cooling tower system. In the examples, the water temperature was 15 ° C. for the winter experiment.

An example of equipment used for carrying out the method of the present invention is schematically shown in FIG.

Explanation of symbols

1. 1. Drying device 2. Blower blade Motor 4. Blower 5 A heat exchanger (for heating)
6). Boiler 7. B heat exchanger (for cooling)
8). Cooler 9. Vacuum air discharge pipe 10. Vacuum pump 11. A guide plate 12. B guide plate 13. Dry sample 14. Sample tray 15. A passage duct for circulating air 19. B. Passing duct passed through the heat exchanger 7. 15. A mixed gas of air that has passed through the passage ducts 15 and 16. Air that has passed through the A heat exchanger 5 19. Air that has passed through the dried product 13 20. Dry sample supply device
21. Separation network
22. Dry matter discharge device
23. Perforated plate
24. Spray drying room
25. Dry matter retention part
26. Filter cloth
27. Spraying equipment
28. Dry matter discharge device
29. Stirrer
30. Stirring power unit
31. Drainage retention tank
32. Outside air introduction valve

The block diagram of the shelf-type drying apparatus which shows one Embodiment of this invention is shown. The block diagram of the shelf-type cooling device which shows one Embodiment of this patent is shown. The block diagram of the stirring-type drying apparatus which shows one Embodiment of this patent is shown. The block diagram of the fluidized-bed-type drying apparatus which shows one Embodiment of this patent is shown. The block diagram of the spray-drying apparatus of the circulating gas atmosphere which shows one Embodiment of this patent is shown. 1 shows a block diagram of a single-overgas spray drying apparatus showing an embodiment of the present patent. FIG.

The present invention relates to a food drying apparatus with little change in quality.

Conventional technology

Drying with little change in quality is performed by vacuum drying, freeze drying, or natural drying using winter cold wind. The drying temperature that determines the quality of the vacuum drying device or freeze drying device is a temperature determined by the relationship between the degree of vacuum and the boiling point of the evaporated substance (usually water). The energy of evaporation of the dry matter depends on the heat transfer energy from the tray on which the sample is loaded and the radiant heat from the container wall.

However, in the conventional method as described above, the heat supply rate to the dried product is low, and increasing the temperature of the tray in order to increase the heat supply rate has caused a great influence on the quality.

This invention makes it a subject to provide the method which can manufacture a high quality dried material in a short time and low cost in view of the above problems.

In the present invention, high-quality drying can be produced in a short time and at low cost, and vacuum cooling can be performed at low cost.

Although the drying temperature was set to 30 ° C. as a problem, this is a temporary target value, and the temperature of quality change differs depending on the sample, so it is not particularly fixed.

In the present invention, in addition to the shelf type which is dried by convection of air having a pressure of 0.1 to 0.5 atm or less, fluidized bed drying (FIG. 4), spray drying (FIG. 5), vibration drying, dry matter on the plate surface It can be applied to the method of adhering and drying, vacuum cooling, etc.

Means for solving the problem

In order to solve the above problems, the following several problems have been devised.

First, it was based on convection drying of vacuum air. Consider the conditions necessary for that.

First, the size of the blower is devised. There is some gas in the vacuum gas corresponding to the pressure. A method of moving the gas in mass is devised. The amount of gas transported by the blower depends on the blade size and the number of rotations. For example, a blower having a transport capacity of 100 kw at normal pressure is considered to have a capacity of 1 kw under a vacuum of 1/100. The type of blower is determined by the transport volume and transport resistance. The resistance is selected according to the required pressure such as propeller, sirocco, turbo, roots, piston. The amount of energy transport during drying is mass. The actual power required for the blower varies greatly depending on the efficiency due to the sliding of the blade surface. In this patent, the drying method is selected according to the method suitable for the degree of vacuum appropriate for the purpose of drying, the temperature of the dried product, the device structure, etc., the device components are selected, and the power is selected. The fluctuation range of power greatly exceeds the range controlled by the inverter. As shown in the claim, it is composed of 1/2 of the required power during operation under normal pressure, preferably 1/5 to 1/20, much less than the power required for operation under normal pressure. A blower was used.

Next, consider the saturated moisture content of air under vacuum. Non-Patent Document 1 (Chemical Engineering Handbook, May 10, 1968, revised edition 3rd edition issued, editor. Chemical Engineering Association of Japan, p34) "Saturation temperature of high-pressure air" shown in Fig. 1.28 The values of 20 ° C. obtained by extrapolating the diagram to the low-pressure conditions are 0.1, 0.2, 0.3 kg / cm ² , and the water contents are 0.2, 0.09, 0.06 kg / kg, respectively. is there. Compared with the fact that the moisture content of air at 20 ° C. at 1 atm is 0.015 kg / kg, the moisture transport amount of 1 kg of vacuum air is about 0.1, 0.2 and 0.3 kg / cm ² respectively. 1/13, 1/6, and 1/4 are possible. The effect of using this phenomenon for the transport phenomenon of dry air is very significant.

Chemical Engineering Handbook, 3rd edition, revised on May 10, 1968, editor. Japan Society for Chemical Engineering

The pressure of 0.2 kg / cm ² is in the range of the degree of vacuum that is easily possible with a water ring vacuum pump.

Next, consider the drying temperature at which the dried product is in a convection gas atmosphere. The ambient temperature of the dried product affects the energy transfer rate to the dried product, but not the temperature that directly affects the quality of the dried product. The quality of the dried product is the temperature at the site where moisture is evaporated. It was experimentally confirmed that these general theories in the drying phenomenon under normal pressure can be applied to the convection drying phenomenon of dilute air under vacuum.
In the method of the present invention, the dew point temperature of the convection gas indicates the drying temperature. The dew point in the method of this patent is the temperature of the cooling heat medium of the heat exchanger. When cooling with a cooling tower using outside air, the dew point is the temperature of the cooling water, and the temperature made with the refrigerator is the dew point temperature.

1. Select a blower that considers mass transport of air under vacuum,
2. Consider the pressure, temperature, moisture in the air under vacuum,
3. Considering that the quality of the dried product under vacuum is greatly affected by the temperature of the moisture location,
4). Considering many equipment costs such as the drying chamber, vacuum pump, heat supply, heat discharge, air flow, etc.
5. As a result of comprehensively considering the above items 1 to 4 and devising the best drying device, the indoor pressure of the drying device 1 shown in FIG. 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, A heat exchanger 5 that installs a blower 4 configured with a power of 1/2, preferably 1/5 to 1/10 of the power required when rotating under atmospheric pressure, and gives energy to the indoor gas of the drying apparatus 1. A heat source generator 6 that supplies a heat source to the heat exchanger 5, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, and a heat exchanger that converts the moisture of the indoor gas of the drying device 1 into liquid or ice. 7, a cooling device 8 that cools the energy obtained by the heat exchanger 7, a conduit 9 that maintains the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10 are used as a basic configuration. The basic idea of this patent can be applied to many drying methods. As an example, a shelf type, a flow type and a spray type are shown.

The humidity of the circulating gas was made possible by introducing a part of the circulating gas into the heat exchanger for collecting condensed water.

In drying under vacuum drying, it was confirmed that the temperature difference between the ambient temperature of the dried product and the dew point temperature affects the heat flow rate supplied to the sample.

  It dried using the apparatus shown in FIG. The configuration of FIG. 1 will be described. The drying chamber 1 is a container that can hold a vacuum. In the chamber, a blower 4 composed of a blower blade 2 and a power 3 that rotates the blower blade 2, and a heat exchanger 5 that gives energy to the indoor gas of the drying device 1, A boiler 6 for supplying steam to the heat exchanger 5, a heat exchanger 7 for condensing the water vapor generated by drying into liquid water, a device 8 for cooling the energy obtained in the heat exchanger 7, and a vacuum gas It comprises a duct 9 led out to the outdoors, a vacuum pump 10, a tray 14 on which a dried sample 13 is loaded, and guide plates 11 and 12 that circulate the room gas of the drying apparatus 1.

A supplementary description will be given of the configuration contents of FIG.
The tray 14 may be a wire mesh or a perforated plate on which a sample can be loaded and held, and it is not necessary to use a hot plate that guides vapor from a boiler for giving drying energy to the sample from the tray by a conduit or heating with a heater.

The gas flow 17 generated in the blower 4 becomes a gas flow 18 through the heat exchanger 5, passes through the sample 13 and becomes a gas flow 19, and a part of the gas flow 19 passes through a duct formed by the guide plates 11 and 12. Thus, a part of the gas flow 19 becomes a gas flow 16 passing through the heat exchanger 7, and the gas flows 15 and 16 merge to form a gas flow 17, which constitutes a gas circulation reaching the blower 4.
The same effect can be expected even if the gas flow direction of the drying apparatus of FIGS.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a tray 14 on which a dried sample 13 is loaded, a heat exchanger 5 that gives energy to the indoor gas of the drying apparatus 1, and a heat exchanger 5 A heat source generator 6 that supplies a heat source, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, a heat exchanger 7 that converts the moisture of the indoor gas of the drying device 1 into liquid or ice, and a heat exchanger 7 The drying device is composed of a cooling device 8 for cooling the energy obtained in the above, a conduit 9 for maintaining the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a tray 14 on which a dried sample 13 is loaded, guide plates 11 and 12 for circulating the indoor gas of the drying apparatus 1, and the interior of the drying apparatus 1. A heat exchanger 7 that converts gaseous moisture into liquid or ice, a cooling device 8 that cools the energy obtained in the heat exchanger 7, a conduit 9 that maintains the room pressure of the drying device 1 in vacuum, and a vacuum pump 10 Drying equipment composed of

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a stirrer 29 for stirring the dry sample 13 deposited in the dry sample container 25 is installed in the drying chamber 1, and a power 30 for driving the stirrer 29 A device 20 for supplying a dry sample, a discharge device 22 for discharging the dried product 13, a heat exchanger 5 for providing energy to the indoor gas of the drying device 1, and a heat source generator for supplying a heat source to the heat exchanger 5. 6, the guide plates 11 and 12 that circulate the indoor gas of the drying device 1, the heat exchanger 7 that converts the moisture of the indoor gas of the drying device 1 to liquid or ice, and the energy obtained by the heat exchanger 7 is cooled. A cooling device 8 and a conduit 9 for maintaining the drying chamber in a vacuum; Drying device Drying the sample 13 composed of a vacuum pump 10.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with a power of 1/5 to 1/20, floats the dried sample 13 on the perforated plate 23, discharges the dried sample supply device 20, the plate 21 through which the dried product flows, and discharges the dried product A heat exchanger 5 that gives energy to the indoor gas of the drying device 1, a heat source generator 6 that supplies a heat source to the heat exchanger 5, and guide plates 11 and 12 that circulate the indoor gas of the drying device 1. , A heat exchanger 7 that converts the moisture in the room gas of the drying apparatus 1 to liquid or ice, a cooling device 8 that cools the energy obtained in the heat exchanger 7, a conduit 9 that maintains the drying chamber in vacuum, and a vacuum pump 10 is a drying apparatus.

This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.2 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with power of 1/5 to 1/20 in the drying chamber 1, and supplies a heat source to the heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, and the heat exchanger 5. A heat source generator 6, a spray drying chamber 24 in the drying chamber 1, a duct 18 connected to the spray drying chamber, a spray device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, A dry powder storage unit 25, a discharge valve 28, a duct 19 for returning the wind that has passed through the filter cloth 26, a wind 15 in which the returned air flows to the blower 4 as it is, and a wind 16 that passes through the heat exchanger 7, The heat exchanger 7 that cools the wind 16, the cooling device 8 of the heat exchanger 7, and the drying device 1 A conduit 9 to maintain a chamber pressure of vacuum drying apparatus constituted by a vacuum pump 10.

This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.2 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with power of 1/5 to 1/20 in the drying chamber 1, and supplies a heat source to the heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, and the heat exchanger 5. A heat source generator 6, a spray drying chamber 24 in the drying chamber 1, a duct 18 connected to the spray drying chamber, a spray device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, Cooling of the dry powder storage unit 25, the discharge valve 28, the duct 19 that returns the wind that has passed through the filter cloth 26, the wind 15 that circulates as it is, the wind 16 that passes through the heat exchanger 7, and the cooling of the heat exchanger 7 Apparatus 8, conduit 9 for maintaining the room pressure of drying apparatus 1 in vacuum, and vacuum pump 0 to constitute a dry apparatus.

Conventionally, the drying temperature of vacuum drying has been discussed in terms of the boiling point of water. However, since the drying temperature of the present invention is determined by the dew point temperature of the indoor circulating gas, the temperature around the dried product is, for example, 30 ° C. Drying is possible.

Here, in the above sentence, the term “vacuum” is used. However, in general, this level of pressure is often expressed as “decompression”. However, since the vocabulary of vacuum or decompression expresses the same thing, this patent sentence expressed all the pressures lower than normal pressure in vacuum. The normal pressure was 1 atm and the absolute vacuum was 0 atm.

Since the heat supply to the dried sample depends on the energy provided by the convection from the circulating gas, in any drying of this patent apparatus, if the convection is stopped, the energy is not supplied and the drying does not proceed.

The heat supply to the sample is primarily governed by the temperature difference between the temperature on the enthalpy line of the circulating gas and the product temperature.

The drying according to the invention can also be applied to freeze-drying equipment. The drying temperature of lyophilization is the temperature at which ice evaporates, so the ice evaporation temperature of 0 ° C. is the dew point temperature, and lyophilization is possible by a convection gas drying method.

Furthermore, the device of the present invention can be applied to vacuum cooling. In the case of application to vacuum cooling, it is not necessary to supply heat from the boiler, and it is only necessary to place the sample in the circulating gas through the device 8 that cools the energy obtained by the heat exchanger 7.

Cooling by the apparatus of the present invention can be expected to have a greater economic effect on apparatus cost and operation cost than the vacuum cooling method.

Drying test results

As a result of performing a drying test with a carrot thickness of 2 cm and a radish thickness of 3 cm at a degree of vacuum of 0.2 atm and a temperature of 60 ° C., the drying temperature could be maintained at 25 to 28 ° C. A product without discoloration of the dried product was obtained.

This drying temperature course shows that it is dried at the dew point temperature, and the temperature does not differ depending on whether the water in the vegetable tissue is liquid or solid.

It is possible to dry vegetables with little change in target quality with a water-sealed vacuum pump.

All samples having an evaporating component as a sample to be dried are possible.

  Although it changes with areas and time, the cooling device 11 can be a cooling tower system. In the examples, the water temperature was 15 ° C. for the winter experiment.

It is a schematic diagram of an example of a drying device used for carrying out the method of the present invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention.

Explanation of symbols

1. 1. Drying device 2. Blower blade Motor 4. Blower 5 A heat exchanger (for heating)
6). Boiler 7. B heat exchanger (for cooling)
8). Cooler 9. Vacuum air discharge pipe 10. Vacuum pump 11. A guide plate 12. B guide plate 13. Dry sample 14. Sample tray 15. A passage duct for circulating air 19. B. Passing duct passed through the heat exchanger 7. 15. A mixed gas of air that has passed through the passage ducts 15 and 16. Air that has passed through the A heat exchanger 5 19. Air that has passed through the dried product 13 20. Dry sample supply device
21. Separation network
22. Dry matter discharge device
23. Perforated plate
24. Spray drying room
25. Dry matter retention part
26. Filter cloth
27. Spraying equipment
28. Dry matter discharge device
29. Stirrer
30. Stirring power unit
31. Drainage retention tank
32. Outside air introduction valve

The present invention relates to a food drying apparatus with little change in quality.

Conventional technology

Drying with little change in quality is performed by vacuum drying, freeze drying, or natural drying using winter cold wind. The drying temperature that determines the quality of the vacuum drying device or freeze drying device is a temperature determined by the relationship between the degree of vacuum and the boiling point of the evaporated substance (usually water). The energy of evaporation of the dry matter depends on the heat transfer energy from the tray on which the sample is loaded and the radiant heat from the container wall.

However, in the conventional method as described above, the heat supply rate to the dried product is low, and increasing the temperature of the tray in order to increase the heat supply rate has caused a great influence on the quality.

This invention makes it a subject to provide the method which can manufacture a high quality dried material in a short time and low cost in view of the above problems.

In the present invention, high-quality drying can be produced in a short time and at low cost, and vacuum cooling can be performed at low cost.

Although the drying temperature was set to 30 ° C. as a problem, this is a temporary target value, and the temperature of quality change differs depending on the sample, so it is not particularly fixed.

In the present invention, in addition to the shelf type which is dried by convection of air having a pressure of 0.1 to 0.5 atm or less, fluidized bed drying (FIG. 4), spray drying (FIG. 5), vibration drying, dry matter on the plate surface It can be applied to the method of adhering and drying, vacuum cooling, etc.

Means for solving the problem

In order to solve the above problems, the following several problems have been devised.

First, it was based on convection drying of vacuum air. Consider the conditions necessary for that.

First, the size of the blower is devised. There is some gas in the vacuum gas corresponding to the pressure. A method of moving the gas in mass is devised. The amount of gas transported by the blower depends on the blade size and the number of rotations. For example, a blower having a transport capacity of 100 kw at normal pressure is considered to have a capacity of 1 kw under a vacuum of 1/100. The type of blower is determined by the transport volume and transport resistance. The resistance is selected according to the required pressure such as propeller, sirocco, turbo, roots, piston. The amount of energy transport during drying is mass. The actual power required for the blower varies greatly depending on the efficiency due to the sliding of the blade surface. In this patent, the drying method is selected according to the method suitable for the degree of vacuum appropriate for the purpose of drying, the temperature of the dried product, the device structure, etc., the device components are selected, and the power is selected. The fluctuation range of power greatly exceeds the range controlled by the inverter. As shown in the claim, it is composed of 1/2 of the required power during operation under normal pressure, preferably 1/5 to 1/20, much less than the power required for operation under normal pressure. A blower was used.

Next, consider the saturated moisture content of air under vacuum. Non-Patent Document 1 (Chemical Engineering Handbook, May 10, 1968, revised edition 3rd edition issued, editor. Chemical Engineering Association of Japan, p34) "Saturation temperature of high-pressure air" shown in Fig. 1.28 The values of 20 ° C. obtained by extrapolating the diagram to the low-pressure conditions are 0.1, 0.2, 0.3 kg / cm ² , and the water contents are 0.2, 0.09, 0.06 kg / kg, respectively. is there. Compared with the fact that the moisture content of air at 20 ° C. at 1 atm is 0.015 kg / kg, the moisture transport amount of 1 kg of vacuum air is about 0.1, 0.2 and 0.3 kg / cm ² respectively. 1/13, 1/6, and 1/4 are possible. The effect of using this phenomenon for the transport phenomenon of dry air is very significant.

Chemical Engineering Handbook, 3rd edition, revised on May 10, 1968, editor. Japan Society for Chemical Engineering

The pressure of 0.2 kg / cm ² is in the range of the degree of vacuum that is easily possible with a water ring vacuum pump.

Next, consider the drying temperature at which the dried product is in a convection gas atmosphere. The ambient temperature of the dried product affects the energy transfer rate to the dried product, but not the temperature that directly affects the quality of the dried product. The quality of the dried product is the temperature at the site where moisture is evaporated. It was experimentally confirmed that these general theories in the drying phenomenon under normal pressure can be applied to the convection drying phenomenon of dilute air under vacuum.
In the method of the present invention, the dew point temperature of the convection gas indicates the drying temperature. The dew point in the method of this patent is the temperature of the cooling heat medium of the heat exchanger. When cooling with a cooling tower using outside air, the dew point is the temperature of the cooling water, and the temperature made with the refrigerator is the dew point temperature.

1. Select a blower that considers mass transport of air under vacuum,
2. Consider the pressure, temperature, moisture in the air under vacuum,
3. Considering that the quality of the dried product under vacuum is greatly affected by the temperature of the moisture location,
4). Considering many equipment costs such as the drying chamber, vacuum pump, heat supply, heat discharge, air flow, etc.
5. As a result of comprehensively considering the above items 1 to 4 and devising the best drying device, the indoor pressure of the drying device 1 shown in FIG. 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, A heat exchanger 5 that installs a blower 4 configured with a power of 1/2, preferably 1/5 to 1/10 of the power required when rotating under atmospheric pressure, and gives energy to the indoor gas of the drying apparatus 1. A heat source generator 6 that supplies a heat source to the heat exchanger 5, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, and a heat exchanger that converts the moisture of the indoor gas of the drying device 1 into liquid or ice. 7, a cooling device 8 that cools the energy obtained by the heat exchanger 7, a conduit 9 that maintains the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10 are used as a basic configuration. The basic idea of this patent can be applied to many drying methods. As an example, a shelf type, a flow type and a spray type are shown.

The humidity of the circulating gas was made possible by introducing a part of the circulating gas into the heat exchanger for collecting condensed water.

In drying under vacuum drying, it was confirmed that the temperature difference between the ambient temperature of the dried product and the dew point temperature affects the heat flow rate supplied to the sample.

  It dried using the apparatus shown in FIG. The configuration of FIG. 1 will be described. The drying chamber 1 is a container that can hold a vacuum. In the chamber, a blower 4 composed of a blower blade 2 and a power 3 that rotates the blower blade 2, and a heat exchanger 5 that gives energy to the indoor gas of the drying device 1, A boiler 6 for supplying steam to the heat exchanger 5, a heat exchanger 7 for condensing the water vapor generated by drying into liquid water, a device 8 for cooling the energy obtained in the heat exchanger 7, and a vacuum gas It comprises a duct 9 led out to the outdoors, a vacuum pump 10, a tray 14 on which a dried sample 13 is loaded, and guide plates 11 and 12 that circulate the room gas of the drying apparatus 1.

A supplementary description will be given of the configuration contents of FIG.
The tray 14 may be a wire mesh or a perforated plate on which a sample can be loaded and held, and it is not necessary to use a hot plate that guides vapor from a boiler for giving drying energy to the sample from the tray by a conduit or heating with a heater.

The gas flow 17 generated in the blower 4 becomes a gas flow 18 through the heat exchanger 5, passes through the sample 13 and becomes a gas flow 19, and a part of the gas flow 19 passes through a duct formed by the guide plates 11 and 12. Thus, a part of the gas flow 19 becomes a gas flow 16 passing through the heat exchanger 7, and the gas flows 15 and 16 merge to form a gas flow 17, which constitutes a gas circulation reaching the blower 4.
The same effect can be expected even if the gas flow direction of the drying apparatus of FIGS.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a tray 14 on which a dried sample 13 is loaded, a heat exchanger 5 that gives energy to the indoor gas of the drying apparatus 1, and a heat exchanger 5 A heat source generator 6 that supplies a heat source, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, a heat exchanger 7 that converts the moisture of the indoor gas of the drying device 1 into liquid or ice, and a heat exchanger 7 The drying device is composed of a cooling device 8 for cooling the energy obtained in the above, a conduit 9 for maintaining the room pressure of the drying device 1 in vacuum, and a vacuum pump 10.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a tray 14 on which a dried sample 13 is loaded, guide plates 11 and 12 for circulating the indoor gas of the drying apparatus 1, and the interior of the drying apparatus 1. A heat exchanger 7 that converts gaseous moisture into liquid or ice, a cooling device 8 that cools the energy obtained in the heat exchanger 7, a conduit 9 that maintains the room pressure of the drying device 1 in vacuum, and a vacuum pump 10 Drying equipment composed of

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Is provided with a blower 4 configured with a power of 1/5 to 1/20, a stirrer 29 for stirring the dry sample 13 deposited in the dry sample container 25 is installed in the drying chamber 1, and a power 30 for driving the stirrer 29 A device 20 for supplying a dry sample, a discharge device 22 for discharging the dried product 13, a heat exchanger 5 for providing energy to the indoor gas of the drying device 1, and a heat source generator for supplying a heat source to the heat exchanger 5. 6, the guide plates 11 and 12 that circulate the indoor gas of the drying device 1, the heat exchanger 7 that converts the moisture of the indoor gas of the drying device 1 to liquid or ice, and the energy obtained by the heat exchanger 7 is cooled. A cooling device 8 and a conduit 9 for maintaining the drying chamber in a vacuum; Drying device Drying the sample 13 composed of a vacuum pump 10.

This will be described with reference to FIG. The room pressure of the drying apparatus 1 is maintained at 0.1 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with a power of 1/5 to 1/20, floats the dried sample 13 on the perforated plate 23, discharges the dried sample supply device 20, the plate 21 through which the dried product flows, and discharges the dried product A heat exchanger 5 that gives energy to the indoor gas of the drying device 1, a heat source generator 6 that supplies a heat source to the heat exchanger 5, and guide plates 11 and 12 that circulate the indoor gas of the drying device 1. , A heat exchanger 7 that converts the moisture in the room gas of the drying apparatus 1 to liquid or ice, a cooling device 8 that cools the energy obtained in the heat exchanger 7, a conduit 9 that maintains the drying chamber in vacuum, and a vacuum pump 10 is a drying apparatus.

This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.2 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with power of 1/5 to 1/20 in the drying chamber 1, and supplies a heat source to the heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, and the heat exchanger 5. A heat source generator 6, a spray drying chamber 24 in the drying chamber 1, a duct 18 connected to the spray drying chamber, a spray device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, A dry powder storage unit 25, a discharge valve 28, a duct 19 for returning the wind that has passed through the filter cloth 26, a wind 15 in which the returned air flows to the blower 4 as it is, and a wind 16 that passes through the heat exchanger 7, The heat exchanger 7 that cools the wind 16, the cooling device 8 of the heat exchanger 7, and the drying device 1 A conduit 9 to maintain the chamber pressure in the vacuum drying apparatus constituted by a vacuum pump 10.

This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.2 atm to 0.5 atm, preferably 0.2 atm to 0.3 atm, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably Installs the blower 4 configured with power of 1/5 to 1/20 in the drying chamber 1, and supplies a heat source to the heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, and the heat exchanger 5. A heat source generator 6, a spray drying chamber 24 in the drying chamber 1, a duct 18 connected to the spray drying chamber, a spray device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, Cooling of the dry powder storage unit 25, the discharge valve 28, the duct 19 that returns the wind that has passed through the filter cloth 26, the wind 15 that circulates as it is, the wind 16 that passes through the heat exchanger 7, and the cooling of the heat exchanger 7 Apparatus 8, conduit 9 for maintaining the room pressure of drying apparatus 1 in vacuum, and vacuum pump 0 to constitute a dry apparatus.

Conventionally, the drying temperature of vacuum drying has been discussed in terms of the boiling point of water. However, since the drying temperature of the present invention is determined by the dew point temperature of the indoor circulating gas, the temperature around the dried product is, for example, 30 ° C. Drying is possible.

Here, in the above sentence, the term “vacuum” is used. However, in general, this level of pressure is often expressed as “decompression”. However, since the vocabulary of vacuum or decompression expresses the same thing, this patent sentence expressed all the pressures lower than normal pressure in vacuum. The normal pressure was 1 atm and the absolute vacuum was 0 atm.

Since the heat supply to the dried sample depends on the energy provided by the convection from the circulating gas, in any drying of this patent apparatus, if the convection is stopped, the energy is not supplied and the drying does not proceed.

The heat supply to the sample is primarily governed by the temperature difference between the temperature on the enthalpy line of the circulating gas and the product temperature.

The drying according to the invention can also be applied to freeze-drying equipment. The drying temperature of lyophilization is the temperature at which ice evaporates, so the ice evaporation temperature of 0 ° C. is the dew point temperature, and lyophilization is possible by a convection gas drying method.

Furthermore, the device of the present invention can be applied to vacuum cooling. In the case of application to vacuum cooling, it is not necessary to supply heat from the boiler, and it is only necessary to place the sample in the circulating gas through the device 8 that cools the energy obtained by the heat exchanger 7.

Cooling by the apparatus of the present invention can be expected to have a greater economic effect on apparatus cost and operation cost than the vacuum cooling method.

Drying test results

As a result of performing a drying test with a carrot thickness of 2 cm and a radish thickness of 3 cm at a degree of vacuum of 0.2 atm and a temperature of 60 ° C., the drying temperature could be maintained at 25 to 28 ° C. A product without discoloration of the dried product was obtained.

This drying temperature course shows that it is dried at the dew point temperature, and the temperature does not differ depending on whether the water in the vegetable tissue is liquid or solid.

It is possible to dry vegetables with little change in target quality with a water-sealed vacuum pump.

All samples having an evaporating component as a sample to be dried are possible.

  Although it changes with areas and time, the cooling device 11 can be a cooling tower system. In the examples, the water temperature was 15 ° C. for the winter experiment.

It is a schematic diagram of an example of a drying device used for carrying out the method of the present invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention. It is the schematic of the drying apparatus which shows the other Example of this invention.

Explanation of symbols

1. 1. Drying device 2. Blower blade Motor 4. Blower
5. Heat exchanger 6. boiler
7). Heat exchanger 8. Cooler
9. Conduit 10. Vacuum pump 11. A guide plate 12. B guide plate 13. Dry sample 14. Sample tray
15. Wind
16. Wind 17. 15. A mixed gas of air that has passed through the passage ducts 15 and 16. Air that has passed through the A heat exchanger 5 19. Air that has passed through the dried product 13 20. Dry sample supply device
21. Separation network
22. Dry matter discharge device
23. Perforated plate
24. Spray drying room
25. Dry matter retention part
26. Filter cloth
27. Spraying equipment
28. Dry matter discharge device
29. Stirrer
30. Stirring power unit
31. Missing number
32. Outside air introduction valve

Claims (6)

This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / A fan 4 configured with 20 motive power, a tray 14 on which a dried sample 13 is loaded, a heat exchanger 5 that gives energy to the indoor gas of the drying apparatus 1, and a heat source generator that supplies a heat source to the heat exchanger 5 6, the guide plates 11 and 12 that circulate the indoor gas of the drying device 1, the heat exchanger 7 that converts the moisture of the indoor gas of the drying device 1 to liquid or ice, and the energy obtained by the heat exchanger 7 is cooled. A drying device comprising a cooling device 8, a conduit 9 for maintaining the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10. This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / A blower 4 configured with 20 motive power is installed, a tray 14 on which a dried sample 13 is loaded, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, and moisture in the indoor gas of the drying device 1 is liquid or ice. A drying apparatus comprising: a heat exchanger 7 for cooling, a cooling device 8 for cooling the energy obtained by the heat exchanger 7, a conduit 9 for maintaining the room pressure of the drying device 1 in a vacuum, and a vacuum pump 10. This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / A blower 4 configured with power of 20 is installed, a stirrer 29 for stirring the dry sample 13 deposited in the dry sample container 25 is installed in the drying chamber 1, and a power 30 for driving the stirrer 29 and a dry sample are supplied. A device 20, a discharge device 22 that discharges the dried product 13, a heat exchanger 5 that gives energy to the indoor gas of the drying device 1, a heat source generator 6 that supplies a heat source to the heat exchanger 5, and a drying device 1 Guide plates 11 and 12 that circulate the indoor gas, a heat exchanger 7 that converts the moisture in the indoor gas of the drying device 1 to liquid or ice, a cooling device 8 that cools the energy obtained by the heat exchanger 7, and a drying chamber And the vacuum pump 1 Drying device Drying the sample 13 composed of a. This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / The blower 4 configured with power of 20 is installed, the dried sample 13 is floated on the perforated plate 23, the dried sample supply device 20, the plate 21 through which the dried product flows out, the dried product discharge device 22, and the drying device 1 A heat exchanger 5 that gives energy to the indoor gas, a heat source generator 6 that supplies a heat source to the heat exchanger 5, guide plates 11 and 12 that circulate the indoor gas of the drying device 1, and an indoor gas of the drying device 1. A drying apparatus comprising a heat exchanger 7 for converting the water content into liquid or ice, a cooling device 8 for cooling the energy obtained by the heat exchanger 7, a conduit 9 for maintaining the drying chamber in a vacuum, and a vacuum pump 10. . This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / A blower 4 configured with power of 20 is installed in the drying chamber 1, a heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, a heat source generator 6 that supplies a heat source to the heat exchanger 5, and drying A spray drying chamber 24 in the chamber 1, a duct 18 connected to the spray drying chamber, a spraying device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, a dry powder reservoir 25, The exhaust valve 28, the duct 19 for returning the wind that has passed through the filter cloth 26, the wind 15 in which the returned wind flows directly to the blower 4, the wind 16 passing through the heat exchanger 7, and the heat exchange for cooling the wind 16 The chamber pressure of the heat exchanger 7, the cooling device 8 of the heat exchanger 7, and the drying device 1. A conduit 9 to keep the drying apparatus consists of a vacuum pump 10. This will be described with reference to FIG. The indoor pressure of the drying apparatus 1 is maintained at 0.5 atm or lower, preferably 0.3 atm or lower, and is 1/2 of the power required when the blower blades are rotated under atmospheric pressure, preferably 1/5 to 1 / A blower 4 configured with power of 20 is installed in the drying chamber 1, a heat exchanger 5 that gives energy to the indoor gas of the drying and drying apparatus 1, a heat source generator 6 that supplies a heat source to the heat exchanger 5, and drying A spray drying chamber 24 in the chamber 1, a duct 18 connected to the spray drying chamber, a spraying device 27 for spraying a dried sample, a filter cloth 26 for collecting dried dry powder, a dry powder reservoir 25, The exhaust valve 28, the duct 19 that returns the wind that has passed through the filter cloth 26, the wind 15 that circulates as it is, the wind 16 that passes through the heat exchanger 7, the cooling device 8 of the heat exchanger 7, and the drying device 1 And a vacuum pump 10 for maintaining the chamber pressure in a vacuum. Drying apparatus.

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