JP5785447B2 - Wood dryer control device - Google Patents

Description

The present invention relates to a control equipment for wood drying apparatus for drying the stored in drying chamber timber.

  In general, when artificially drying wood, the wood is stored in a drying chamber, and the temperature of the drying chamber is raised using a heating source to dry the wood. Furthermore, in order to finish wood in a high quality state, humidity adjustment is important in addition to temperature adjustment in the drying chamber. For example, by drying the wood evenly so that the moisture content shows a linear decrease with respect to the drying time, cracking, warping, or discoloration can be prevented, and the quality of the dried wood can be improved.

  However, since the dehumidification amount varies depending on the state of the wood in the drying process, the moisture content does not decrease linearly even when drying is performed with a constant heating amount and dehumidification amount. Therefore, in order to obtain high-quality dry wood, it was necessary to operate the drying apparatus based on a drying schedule consisting of the optimum heating amount and dehumidifying amount corresponding to the drying process. This drying schedule is determined by the type and characteristics of the wood to be dried and differs depending on the wood, so the temperature and humidity in the drying chamber can be adjusted according to the drying schedule set for each wood. is important.

  2. Description of the Related Art Conventionally, an apparatus using a heat pump is known as a drying apparatus that can control the temperature and humidity of wood. This is mainly done by heating the outside air with a condenser of the heat pump and sending heated air into the drying chamber to adjust the temperature of the wood, and exhausting the air heated by the moisture from the wood outside the drying chamber, Humidity adjustment is performed by cooling and dehumidifying.

However, the above-described conventional drying apparatus does not use the high-temperature air in the drying chamber released to the outside and recirculates it, so there is a lot of heat loss due to exhaust, and the input energy of the heating source increases. Yes.
Therefore, Patent Document 1 (Japanese Patent Laid-Open No. 2007-192464) discloses a drying apparatus that can reduce energy consumption and improve thermal efficiency by partially circulating air in a drying chamber.

This drying device introduces air in the drying chamber into the cooling dehumidifier, cools and dehumidifies the air on the evaporation side of the heat pump, and then introduces this air into the air heater and heats it on the condensation side of the heat pump to heat the heated air into the drying chamber. It is the composition which supplies to. Further, in this apparatus, CO ₂ refrigerant is used for the heat pump, and the temperature adjustment is performed by supplying the retained heat of the CO ₂ refrigerant compressed to the supercritical pressure after the evaporation step as a heat source of the air heater installed in the drying chamber, A humidifier is installed in the drying chamber to adjust the humidity.

JP 2007-192464 A

However, although the drying apparatus of Patent Document 1 is effective from the viewpoint of energy efficiency, in the conventional drying apparatus including Patent Document 1, both the temperature and humidity of the drying process accurately follow the drying schedule. There was a problem that it was difficult to make it.
One of the reasons is the problem of humidity followability. Since the humidity that affects the drying of wood is relative humidity, in general, relative humidity is often used for humidity adjustment in the drying chamber. However, since the relative humidity changes depending on the temperature, the humidity changes due to the temperature adjustment separately from the humidity adjustment.

For example, if the temperature in the drying chamber is increased according to the drying schedule, the relative humidity decreases as the temperature increases, so the humidity adjustment cannot catch up with the decrease in humidity, and the actual humidity may fall below the set humidity. In addition, when wood having a high water content such as cedar is dried, the dehumidifying amount of the drying schedule may exceed the capacity of the drying device. In this case, the drying process cannot be performed according to the drying schedule, and the drying time is inevitably extended, resulting in a decrease in processing efficiency.
Thus, in actual operation, it has been difficult to accurately perform temperature adjustment and humidity adjustment simultaneously in accordance with the drying schedule.

In general, the most important point in wood drying technology is drying time and quality. That is, it is important to produce dry wood of “high quality” as soon as possible. The drying cost can be reduced by shortening the drying time, while the product value can be increased by producing high-quality dried wood. Here, in principle, it is known that the drying time mainly depends on the temperature, and the quality mainly depends on the humidity. In other words, in order to reduce the drying cost, the temperature is increased and the drying time is shortened, and in order to increase the quality of the wood, defects such as cracking, warping or discoloration are not generated. Humidity needs to be adjusted with high accuracy.
However, as described above, it has been difficult to perform temperature adjustment and humidity adjustment at the same time with high accuracy. Conventionally, there has been a problem that drying costs are unnecessarily bulky, and dry wood of the required quality cannot be obtained. It sometimes occurred.

  Moreover, there are points to be noted in the drying treatment of wood because the properties differ depending on the type of wood. For example, conifers such as cedar and cypress have a high water content and are hard to crack compared to broad-leaved trees. In addition, hardwoods such as white oak have a more complicated structure than conifers and are susceptible to cracking. The drying schedule is set in consideration of these, but as mentioned above, it was difficult to accurately adjust the temperature and humidity at the same time. There is a risk of reducing efficiency.

Furthermore, another point to be noted in the drying process of wood is due to the use of wood. For example, in wood that requires quality such as furniture and interior materials, it is required to be dried so as not to cause defects that occur in the drying process such as cracking, warping, or discoloration. When low cost is required, it is required to shorten the drying time as much as possible.
However, in the conventional wood drying apparatus, even if the requirements on the apparatus side are satisfied, such as improvement in energy efficiency, an apparatus that can perform optimum drying according to the type and use of the wood as described above is not available. It was not proposed.

Accordingly, the present invention is the conventional view of the art problems, and an object thereof is to provide a control equipment for wood drying apparatus capable of performing optimal drying depending on the timber application and kind.

In order to solve the above problems, a control device of a wood drying apparatus according to the present invention includes a drying chamber in which wood is stored, a cooling dehumidifier that cools and dehumidifies moisture-containing air exhausted from the drying chamber, An air heater that heats the cooling dehumidified air from the cooling dehumidifier, and a blower that forms an air flow in which the air exhausted from the drying chamber is returned to the drying chamber through the cooling dehumidifier and the air heater, A control device of a wood drying apparatus for drying the wood based on a drying schedule including an optimum temperature and humidity set for each wood by heating dehumidified air returned to the drying chamber, wherein the wood drying speed is controlled. A drying mode selection means for selecting one drying mode from a plurality of drying modes including a high-speed drying mode emphasizing and a high-quality drying mode emphasizing the quality of the wood; A control logic is set for each drying mode, and a rotation speed calculating means for calculating the rotation speed of the blower using the control logic corresponding to the drying mode selected by the drying mode selection means, and the rotation The gist of the invention is to control the blower so that the number of revolutions calculated by the number calculating means is obtained.

According to this summary , the wood is dried based on the drying schedule. As a general rule, the dehumidification amount and the heating amount are adjusted in each of the cooling dehumidifier and the air heater, and the temperature in the drying chamber is adjusted according to the drying schedule. And maintain humidity. However, as described above, in the drying process of wood, it is difficult to accurately adjust both temperature and humidity in accordance with the drying schedule.
Therefore, in this summary , whether a plurality of drying modes including a high-speed drying mode and a high-quality drying mode are set in advance by the drying mode selection means, giving priority to quality or drying time (drying cost). The drying mode corresponding to the highest priority request can be selected. Thereby, it becomes possible to perform optimal drying according to a use, a kind, etc. of wood. For example, wood that requires quality such as furniture and interior materials needs to be dried so that it does not cause defects in the drying process such as cracking, warping, or discoloration, so select the high quality drying mode. To produce high quality dry wood. On the other hand, for wood that requires low costs such as building materials and structural materials, the high-speed drying mode is selected to reduce the drying cost.

Moreover, in this summary, it is set as the structure which controls the rotation speed of an air blower based on the control logic corresponding to drying mode. When the rotational speed of the blower is controlled, the amount of air passing through the cooling dehumidifier and the air heater increases and decreases, and the cooling and dehumidification amount or heating amount of the air discharged from the drying chamber increases and decreases. Using this action, the temperature and humidity of the heated dehumidified air are finely adjusted by controlling the rotational speed of the blower separately from the temperature and humidity adjustment in each of the cooling dehumidifier and the air heater. Since the rotation speed of the blower can be finely adjusted, the temperature and humidity of the heated dehumidified air can be finely adjusted with high accuracy. As a result, it is possible to perform highly accurate control that can meet the highest priority request (for example, drying cost or quality) in wood drying.

Further, the present subject matter includes first temperature detection means for detecting the temperature in the drying chamber, and the control logic in the high-speed drying mode is configured such that the detected temperature of the first temperature detection means is based on the drying schedule. It is preferable that the number of rotations of the blower be controlled so as to be equal to or higher than the set first set temperature.

As described above, the present summary reliably maintains the temperature in the drying chamber above the temperature necessary for drying the wood by controlling the rotational speed of the blower so that the detected temperature in the drying chamber is equal to or higher than the first set temperature. High speed drying is possible. In this configuration, for example, when the detected temperature in the drying chamber becomes lower than the first set temperature, the rotational speed of the blower is increased. As a result, the amount of air passing through the air heater increases, and the air temperature at the air heater outlet once decreases. Here, the air heater tries to heat up to the set temperature of the drying schedule, so the heating amount is forcibly increased. As a result, the amount of heat applied to the drying chamber increases, and high-speed drying is possible. On the other hand, when the detected temperature in the drying chamber is equal to or higher than the first set temperature, the rotational speed of the blower is maintained because the drying speed is already high. Thereby, high-speed drying can be continued continuously.

And this 1st invention is equipped with the 2nd temperature detection means which detects the temperature of the cooling dehumidification air by the side of the said air heater, and the said control logic of the said high quality drying mode is the detection of the said 2nd temperature detection means temperature Ru configuration der to control the rotational speed of the blower such that the second set temperature that is set lower than the set temperature of the drying chamber.

In this way, by controlling the rotational speed of the blower so that the detected temperature of the cooling dehumidified air at the inlet side of the air heater becomes the second set temperature, the temperature of the cooling dehumidified air is always lower than the temperature in the drying chamber. This means that cooling and dehumidification is reliably performed by the cooling dehumidifier. Therefore, it is possible to accurately adjust the humidity in the cooling dehumidifier.
In this configuration, for example, when the detected temperature of the cooled dehumidified air exceeds the second set temperature, the rotational speed of the blower is decreased. Thereby, the amount of air passing through the cooling dehumidifier is reduced, and the dehumidification amount is reduced. On the other hand, since the amount of air passing through the air heater also decreases, the amount of heating decreases, the temperature in the drying chamber decreases, and the relative humidity in the drying chamber increases.
On the other hand, when the detected temperature of the cooling dehumidified air is lower than the second set temperature, the rotational speed of the blower is increased. Thereby, the amount of air passing through the cooling dehumidifier increases, and the dehumidification amount increases. On the other hand, since the amount of air passing through the air heater also increases, the amount of heating increases, the temperature in the drying chamber increases, and the relative humidity in the drying chamber decreases.
By controlling the rotational speed of the blower as described above, the humidity in the drying chamber can be precisely controlled.

The second aspect of the invention includes a second temperature detecting means for detecting the temperature of the cooling dehumidified air on the air heater inlet side, and a third temperature detecting means for detecting the temperature of the heated dehumidified air on the air heater outlet side. The plurality of drying modes further includes a normal drying mode that takes into account both the drying speed and quality of the wood, and the control logic of the normal drying mode includes the detected temperature of the second temperature detecting means and the third temperature configuration der to control the rotational speed of the blower such that the temperature difference becomes the set temperature difference which is set in advance between the detected temperature of the temperature detecting means Ru.

In the configuration of the second aspect of the invention , the plurality of drying modes include a normal drying mode that takes into account both the drying speed and quality of wood. This normal drying mode is a mode located between the high speed drying mode and the high quality drying mode from the viewpoint of drying time and quality. By including this mode, the range of mode selection is widened, and the quality required as a product. Alternatively, it is possible to perform a more optimal drying process in terms of cost and the like.

Moreover, it is preferable that the said drying mode is selected by the said drying mode selection means according to the use or kind of the said wood.
In this way, by selecting the drying mode according to the use or type of wood, it is possible to perform an optimal drying process according to the required quality or cost.

  Furthermore, a first temperature detection means for detecting the temperature in the drying chamber, an evaporator for supplying cold to the cooling dehumidifier, a compressor, a heat pump including the air heater and an expansion valve, and heating dehumidification on the outlet side of the air heater Compressor control means for controlling the number of revolutions of the compressor based on a temperature setting value of air, and a state in which the detected temperature of the first temperature detection means is out of the set temperature range of the drying schedule for a certain period of time When the above is continued, it is preferable to change the temperature set value of the heated dehumidified air.

  As described above, when adjusting the temperature of the heated dehumidified air, the temperature setting value of the heated dehumidified air is changed when the detected temperature in the drying chamber is outside the set temperature range of the drying schedule for a certain period of time or longer. By doing so, it is possible to perform control in consideration of a response delay with respect to the rotational speed control of the blower, and it is possible to improve control accuracy.

The control method of the wood drying apparatus according to the present subject matter, the moisture-containing air exhausted from the drying chamber timber is accommodated is circulated by the drying chamber outside by the blower, moistened cooling dividing the moisture laden air in the cooling dehumidifier The post-cooling dehumidified air is heated with an air heater so that the heated dehumidified air is returned to the drying chamber. A method for controlling a wood drying apparatus for drying, comprising: a plurality of drying modes including a high-speed drying mode that emphasizes the drying speed of the wood and a high-quality drying mode that emphasizes the quality of the wood; Control logic is set for each mode, and one drying mode is selected from the plurality of drying modes according to the use or type of the wood, and the selected one is selected. On the basis of the control logic corresponding to drying mode and controls the rotational speed of the blower.

In the high-speed drying mode, the rotational speed of the blower is controlled so that the detected temperature in the drying chamber is equal to or higher than the temperature set in the drying schedule. In the high-quality drying mode, the detected humidity in the drying chamber is It is preferable to control the rotation speed of the blower so as to meet the set humidity of the drying schedule.
Further, the plurality of drying modes further include a normal drying mode that takes into account both the drying speed and quality of the wood, and in the normal drying mode, the detected temperature and detected humidity in the drying chamber are set and set in the drying schedule. It is preferable to control the rotation speed of the blower so as to approach the humidity.

As described above, according to the present invention, a drying mode corresponding to a request with the highest priority can be selected from a plurality of drying modes including a high speed drying mode and a high quality drying mode. Thereby, it becomes possible to perform optimal drying according to a use, a kind, etc. of wood.
Moreover, since it is set as the structure which controls the rotation speed of an air blower based on drying mode, it becomes possible to finely adjust the temperature and humidity of heating dehumidification air accurately.

It is a whole block diagram of the wood drying apparatus containing the control apparatus which concerns on embodiment of this invention. It is a graph which shows an example of the drying schedule of wood. It is a figure which shows the specific structural example of the control apparatus in embodiment of this invention. It is a control block diagram in the control logic of a high-speed drying mode. It is a figure explaining the followability with respect to the drying schedule at the time of high-speed drying mode driving | operation, (A) is a graph which shows the setting temperature of a drying schedule, and the detected temperature in a drying room, (B) is the humidity set in a drying schedule, and a drying room. It is a graph which shows the detected humidity. It is a control block diagram in the control logic of a high quality drying mode. It is a figure explaining the followability with respect to the drying schedule at the time of high quality drying mode driving | operation, (A) is a graph which shows the setting temperature of a drying schedule, and the detected temperature in a drying chamber, (B) is the humidity and drying which are setting of a drying schedule. It is a graph which shows indoor detection humidity. It is a control block diagram in the control logic of normal drying mode. It is a figure explaining the followability with respect to the drying schedule at the time of normal drying mode driving | operation, (A) is a graph which shows the preset temperature of a drying schedule, and the detected temperature in a drying chamber, (B) is the setting humidity of a drying schedule, and a drying chamber. It is a graph which shows the detected humidity. An example of the drying schedule according to a wood kind is shown, (A) is a figure which shows the drying schedule of a cedar, (B) is a figure which shows the drying schedule of white oak. An example of a drying schedule according to wood usage is shown, (A) is a diagram showing a drying schedule of interior wood, (B) is a diagram showing a drying schedule of general building materials, and (C) is allowed to discolor. It is a figure which shows the drying schedule of general building materials. It is a flowchart which shows the control method of the wood drying apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the change method of the temperature setting value of heating dehumidification air, (A) is a graph which shows the preset temperature and detection temperature in a drying chamber, (B) is the preset temperature and change before heating dehumidification air It is a graph which shows post-setting temperature.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

First, the overall configuration of the wood drying apparatus according to the embodiment of the present invention will be described with reference to FIG.
This wood drying apparatus is mainly disposed on the drying chamber 1 in which the wood W is stored, the air line 3 in which the air exhausted from the drying chamber 1 circulates, and the air line 3, and is exhausted from the drying chamber 1. A cooling dehumidifier 4 that cools and dehumidifies the air, an air heater 15 that heats the air discharged from the cooling dehumidifier 4, and a blower 5 that circulates air on the air line 3.

Further, the wood drying apparatus has a heat pump 10 that supplies cold heat to the cooling dehumidifier 4 and also supplies hot air to the air heater 15.
The heat pump 10 includes a refrigerant line 20 through which a primary refrigerant flows, and an expansion valve 11, an evaporator 12, a compressor 14, and an air heater 15 that are arranged in this order on the refrigerant line 20. Furthermore, the heat pump 10 may have an auxiliary heat exchanger 16 and an internal heat exchanger 13.

As the primary refrigerant circulating through the refrigerant line 20 of the heat pump 10, for example, a CO ₂ refrigerant, an ammonia refrigerant, a Freon refrigerant, or the like can be used. In this embodiment, it is particularly preferable to use a CO ₂ refrigerant, and more preferably. Is preferably a heat pump with a supercritical cycle of CO ₂ refrigerant. This is because a heat source near 100 ° C. can be taken out.
In addition, it is preferable to use water or brine as the medium for transporting the cold heat recovered by the evaporator 12 to the cooling dehumidifier 4 (since the wood condensate (wood vinegar) contains a corrosive component), the secondary refrigerant. Can also be used. In this embodiment, as an example, the case where water is used for this medium is shown.

Next, each component will be described in detail.
The drying chamber 1 stores a wood W that is a water-containing body. Preferably, the timbers W are installed at a distance from each other so that air flows between the timbers. A partition 1a is provided in the drying chamber 1 so as to form a circulating air flow, and a drying chamber circulation fan 2 is disposed in a circulation channel formed by the partition 1a. The drying chamber 1 is also provided with a first temperature sensor 41 that detects the temperature in the drying chamber 1 and a humidity sensor 49 that detects the humidity in the drying chamber 1.

An air line 3 is connected to the drying chamber 1, and the drying chamber 1 including the air line 3 is a closed system. Moisture-containing air containing moisture generated from the wood W is exhausted from the drying chamber 1 to the air line 3. The moisture-containing air is cooled and dehumidified by the cooling dehumidifier 4, and the cooled dehumidified air is heated by the air heater 15, thereby obtaining heated dehumidified air adjusted in temperature and humidity. This heated dehumidified air is returned to the drying chamber 1.
The blower 5 adjusts the amount of air flowing through the air line 3, and for example, a fan or a blower is used. The blower 5 is provided with an inverter control unit 45 that controls the rotation speed. That is, the amount of air flowing through the air line 3 is adjusted by controlling the rotational speed of the blower 5 by the inverter control unit 45. Although FIG. 1 shows a case where the blower 5 is installed in the air line 3 between the cooling dehumidifier 4 and the air heater 15, the position of the blower 5 is not limited to this, and the air line 3 You may install in any position which can form the upper airflow.

As described above, the heat pump 10 is provided with the expansion valve 11, the evaporator 12, the compressor 14, the air heater 15, and the auxiliary heat exchanger 16 in the refrigerant line 20.
In the evaporator 12, heat exchange is performed between the primary refrigerant circulating in the heat pump 10 and the water circulating in the water circulation lines 31 and 34. That is, in the evaporator 12, water is cooled by the evaporation heat of the primary refrigerant decompressed by the expansion valve 11. Then, water having cold heat is sent to the cooling dehumidifier 4 through the water circulation lines 31 and 34, and the moisture-containing air exhausted from the drying chamber 1 and water are heat-exchanged by the cooling dehumidifier 4 so that the moisture-containing air is exchanged. Is dehumidified by cooling.

  Here, a water storage tank 30 is interposed on the water circulation lines 31 and 34, and cold heat is stored therein. Specifically, the water circulation line is a first water circulation line 34 through which water circulates between the evaporator 12 and the water storage tank 30, and a first water circulation line through which water circulates between the water storage tank 30 and the cooling dehumidifier 4. 2 water circulation lines 31. A pump 35 is provided on the first water circulation line 34, and a pump 32 is provided on the second water circulation line 31. The cooling heat supplied to the cooling dehumidifier 4 by controlling the pumps 32 and 35. The amount is to be controlled.

  Further, the first water circulation line 34 has a bypass line that bypasses the evaporator 12, and a three-way valve 36 is disposed at a branch point of the bypass line. The three-way valve 36 selectively selects a line where water discharged from the water storage tank 30 returns to the water storage tank 30 through the evaporator 12 and a line where the water returns to the water storage tank 30 without passing through the evaporator 12. Is set. Similarly, the 2nd water circulation line 31 has a bypass line which bypasses the cooling dehumidifier 4, and the three-way valve 33 is arrange | positioned at the branch point of the bypass line. The three-way valve 33 selects a line for returning the water discharged from the water storage tank 30 through the cooling dehumidifier 4 to the water storage tank 30 and a line for returning to the water storage tank 30 without passing through the cooling dehumidifier 4. Is set automatically. The amount of heat supplied to the cooling dehumidifier 4 can also be controlled by controlling these three-way valves 33 and 35.

The low-pressure gas from the evaporator 12 is introduced into the compressor 14, and the low-pressure gas is compressed to generate a high-temperature high-pressure gas. Further, the compressor 14 is provided with an inverter control unit 46 for controlling the number of rotations thereof.
An internal heat exchanger 13 may be provided between the evaporator 12 and the compressor 14. The internal heat exchanger 13 exchanges heat between the primary refrigerant just before being introduced into the expansion valve 11 and the primary refrigerant just after being discharged from the evaporator 12.
In the air heater 15, heat exchange is performed between the primary refrigerant circulating in the heat pump 10 and the air circulating in the air line 3. That is, in the air heater 15, the dehumidified air discharged from the cooling dehumidifier 4 is heated by the condensation heat of the primary refrigerant discharged from the compressor 11.

  The auxiliary heat exchanger 16 takes in the outside air with the fan 16a and exchanges heat between the outside air and the primary refrigerant. The auxiliary heat exchanger 16 may be configured such that its function is switched depending on the operation method of the wood drying apparatus. For example, the auxiliary heat exchanger 16 may function as a part of a mere refrigerant passage when the fan 16a is turned off, or the primary refrigerant that has passed through the air heater 15 is supplied while the fan 16a is turned on. You may make it function as a thermal radiation means which cools further by external air. Alternatively, the fan 16a may be turned on and the primary refrigerant decompressed by the expansion valve 11 may be supplied, and the fan 16a may function as an evaporating unit that heats and evaporates the primary refrigerant with outside air.

Next, the configuration of a control device that controls the wood drying device having the above-described configuration will be described.
The control device is a device that controls the drying of the wood based on the drying schedule including the optimum temperature and humidity set for each wood. The first controller 50, the second controller 61, the third controller 62, including. The first controller 50, the second controller 61, and the third controller 63 are configured to perform control independently of each other.
Further, as described above, the control device includes the first temperature sensor 41 that detects the temperature in the drying chamber 1, the second temperature sensor 42 that detects the temperature of the cooling dehumidified air on the air heater inlet side, and the air heater outlet side. And a third temperature sensor 43 that detects the temperature of the heated dehumidified air.

The first controller 50 supplies a control signal to the inverter control unit 45 and controls the rotational speed of the blower 5. This configuration will be described later.
The second controller 61 supplies a control signal calculated based on the temperature detected by the second temperature sensor 43 to the inverter control unit 46 of the compressor 14 to control the rotational speed of the compressor 14. Specifically, the second controller 61 calculates the rotational speed of the compressor 14 such that the detected temperature of the heated dehumidified air at the outlet side of the air heater becomes a preset temperature set value, and sends a control signal to the inverter control unit 46. Is output. The inverter control unit 46 controls the rotational speed of the compressor 14 based on this control signal.
The 3rd controller 62 detects the temperature in the water storage tank 30 with the water temperature detection sensor 44, and controls the three-way valves 33 and 36 or the pumps 32 and 35 based on this temperature.

Here, an example of a drying schedule is shown in FIG.
The drying schedule is set for each type of wood (tree species, production area, etc.) or application, and has a configuration in which optimum set temperature and set humidity are arranged in time series when drying the target wood. The set temperature and set humidity may be represented by the temperature and humidity in the drying chamber, or may be represented by a heating amount and a dehumidifying amount. In this embodiment, as an example, the temperature and humidity in the drying chamber are represented.
In the drying schedule illustrated in FIG. 2, the set temperature gradually increases as the drying time advances, but the temperature increase width is smaller in the late drying stage than in the early drying stage. On the other hand, the set humidity gradually decreases as the drying time progresses, but the humidity decrease width is smaller in the late drying stage than in the early drying stage.

In the control apparatus having the above-described configuration, in principle, the second controller 61 and the third controller 62 adjust the dehumidification amount and the heating amount in the cooling dehumidifier 4 and the air heater 15, respectively, and the inside of the drying chamber 1 is in accordance with the drying schedule. The temperature and humidity are adjusted.
However, in the drying treatment of wood, it is difficult to accurately adjust both temperature and humidity according to the drying schedule.
Therefore, in the present embodiment, the first controller 50 performs fine adjustment of the temperature and humidity corresponding to the request with the highest priority in the drying process, such as whether quality is prioritized or whether drying time (drying cost) is prioritized. It has a configuration.

A configuration example of the first controller 50 will be specifically described with reference to FIG.
The first controller 50 uses a drying mode selection means 51 that selects one drying mode from a plurality of preset drying modes, and a rotation that calculates the rotational speed of the blower using control logic corresponding to the selected drying mode. Number arithmetic means 52.
The plurality of drying modes include a high speed drying mode and a high quality drying mode. Preferably, a normal drying mode is included.

  In the first controller 50, first, in accordance with an input signal from the input unit 65, the drying mode selection unit 51 selects one drying mode from a plurality of drying modes. Then, the rotation speed calculation means 52 calculates the rotation speed of the blower 5 using the control logic corresponding to the drying mode selected by the drying mode selection means 51. At this time, the rotation speed calculation means 52 requires the detection temperature of the first temperature sensor 41, the detection temperature of the second temperature sensor 42, and the detection temperature of the third temperature sensor 43, which are required for calculation of the control logic. Is input, and the calculation is performed using this detected temperature. The control signal generated by the calculation of the rotation speed calculation means 52 is output to the inverter control unit 45 of the blower 5. The inverter control unit 45 controls the rotational speed of the blower 5 based on this control signal.

  Thus, according to the said structure, it becomes possible to perform optimal drying according to the use, kind, etc. of wood. For example, wood that requires quality such as furniture and interior materials needs to be dried so that it does not cause defects in the drying process such as cracking, warping, or discoloration, so select the high quality drying mode. To produce high quality dry wood. On the other hand, for wood that requires low costs such as building materials and structural materials, the high-speed drying mode is selected to reduce the drying cost.

  Moreover, in this structure, it is set as the structure which controls the rotation speed of the air blower 5 based on the control logic corresponding to drying mode. When the rotational speed of the blower 5 is controlled, the amount of air passing through the cooling dehumidifier 4 and the air heater 15 is increased or decreased, and the cooling dehumidification amount or heating amount of the air discharged from the drying chamber 1 is increased or decreased. Using this action, the temperature and humidity of the heated dehumidified air are finely adjusted by controlling the rotational speed of the blower 5 separately from the temperature and humidity adjustment in each of the cooling dehumidifier 4 and the air heater 15. Since the rotational speed of the blower 5 can be finely adjusted, the temperature and humidity of the heated dehumidified air can be finely adjusted with high accuracy. As a result, it is possible to perform highly accurate control that can meet the highest priority request (for example, drying cost or quality) in wood drying.

Next, with reference to FIG. 4 thru | or FIG. 9, the control logic of each drying mode is demonstrated in detail.
FIG. 4 is a control block diagram in the high speed drying mode.
In the high speed drying mode, the rotation speed of the blower 5 is controlled so that the detected temperature T1 of the _first temperature sensor 41 is equal to or higher than the first set temperature _TSV1 set based on the dry wood drying schedule. To do.
More specifically, first, the detected temperature T ₁ in the drying chamber detected by the first temperature sensor 41 and the first set temperature T _SV1 are input to the PID calculation unit 521. The PID calculation unit 521 performs a PID calculation based on the deviation between the detected temperature T ₁ in the drying chamber and the first set temperature T _SV1 , generates a control signal, and outputs the control signal to the inverter control unit 45. Here, the detected temperature T ₁ of the drying chamber shows a case of controlling so as to approach the first predetermined temperature T _SV1.

Thus, in high-speed drying mode, by detecting the temperature T ₁ of the drying chamber to control the rotational speed of the blower 5 so that the first set temperature T _SV1 above, it requires temperatures of the drying chamber to the wood drying The temperature is reliably maintained above a certain temperature, and high-speed drying is possible.
In the control of the blower 5, for example, the detected temperature T ₁ of the drying chamber to increase the rotational speed of the blower 5 When a first predetermined temperature below T _SV1. As a result, the amount of air passing through the air heater 15 increases and the air temperature at the outlet of the air heater once decreases. Here, the air heater 15 forcibly increases the heating amount because it tries to heat to the set temperature T _SV1 of the drying schedule. As a result, the amount of heat applied to the drying chamber increases, and high-speed drying is possible. On the other hand, the detected temperature T ₁ of the drying chamber in the case where the first predetermined temperature T _SV1 or already drying rate to maintain the rotational speed of the blower 5 for a fast state. Thereby, high-speed drying can be continued continuously.

5A and 5B are diagrams for explaining the followability to the drying schedule during the high-speed drying mode operation. FIG. 5A is a graph showing the set temperature of the drying schedule and the detected temperature in the drying chamber, and FIG. 5B is the set humidity of the drying schedule. It is a graph which shows the detected humidity in a drying chamber.
By executing the above-described high-speed drying control logic, the detected temperature and the detected humidity in the drying chamber show a follow-up property as illustrated with respect to the set temperature and the set humidity of the drying schedule. As shown in FIG. 5 (A), the detected temperature in the drying chamber changes along or exceeds the set temperature of the drying schedule. On the other hand, as shown in FIG. 5B, the detected humidity in the drying chamber changes below the set humidity of the drying schedule. This is because the humidity followability is partially sacrificed in order to keep the temperature in the drying chamber high. As described above, in the high speed drying mode, since the detected temperature in the drying chamber is controlled to be equal to or higher than the temperature set in the drying schedule, the drying time can be shortened.

FIG. 6 is a control block diagram in the control logic of the high quality drying mode.
In high-quality drying mode, so that the second set temperature T _SV2 that temperature T ₂ for detecting at the second temperature sensor 42 is set lower than the drying chamber temperature, to control the rotational speed of the blower 5.
More specifically, first, the detected temperature T ₂ of the cooling dehumidified air on the air heater inlet side detected by the second temperature sensor 42 and the second set temperature T _SV2 are input to the PID calculation unit 522. The PID calculation unit 522 generates a control signal by performing PID calculation based on the deviation between the temperature T ₂ in the drying chamber detected by the second temperature sensor 42 and the second set temperature T _SV2, and the inverter control unit Output to 45. At this time, a switch 523 that outputs a control signal only when the detected temperature T ₁ of the _first temperature sensor 41 is higher than the detected temperature T _{2 of} the second temperature sensor 42 may be provided.

In the control of the blower 5, for example, the detected temperature T ₂ of the cooling dehumidifying air when it exceeds a second set temperature T _SV2 reduces the rotational speed of the blower 5. Thereby, the amount of air passing through the cooling dehumidifier 4 is reduced, and the amount of dehumidification is reduced. On the other hand, since the amount of air passing through the air heater 15 also decreases, the amount of heating decreases, the temperature in the drying chamber decreases, and the relative humidity in the drying chamber 1 increases.
On the other hand, when the detected temperature T ₂ of the cooling dehumidifying air is below a second predetermined temperature T _SV2 increases the rotational speed of the blower. Thereby, the air quantity which passes the cooling dehumidifier 4 increases, and dehumidification amount increases. On the other hand, since the amount of air passing through the air heater 15 also increases, the amount of heating increases, the temperature in the drying chamber increases, and the relative humidity in the drying chamber 1 decreases.
By controlling the rotation speed of the blower 5 as described above, the humidity in the drying chamber 1 can be precisely controlled according to the set humidity of the drying schedule.

FIG. 7 is a diagram for explaining the followability to the drying schedule during the high-quality drying mode operation. (A) is a graph showing the set temperature of the drying schedule and the detected temperature in the drying chamber, and (B) is the setting of the drying schedule. It is a graph which shows humidity and the humidity detected in a drying chamber.
By executing the above-described high-quality drying control logic, the detected temperature and detected humidity in the drying chamber exhibit a follow-up property as illustrated with respect to the set temperature and set humidity of the drying schedule. As shown in FIG. 7A, the detected temperature in the drying chamber changes below the temperature set in the drying schedule. On the other hand, as shown in FIG. 7B, the detected humidity in the drying chamber changes along with the set humidity of the drying schedule with high accuracy. This is because the humidity in the drying chamber is preferentially adjusted. In this way, in the high-quality drying mode, since the detected humidity in the drying chamber is controlled to match the humidity set in the drying schedule, defects such as cracks, warpage, or discoloration occur. It is difficult to produce high quality dry wood.

FIG. 8 is a control block diagram in the control logic of the normal drying mode.
The normal drying mode is a mode positioned between the high speed drying mode and the high quality drying mode from the viewpoint of drying time and quality.
In usual drying mode, as the detected temperature T ₂ of the second temperature sensor 42, the set temperature difference the temperature difference is previously set between the detected temperature T ₃ of the third temperature sensor 43, the blower 5 Control the number of revolutions.
More specifically, the PID calculation unit 524 first detects the detection temperature T ₂ of the cooling dehumidification air on the air heater inlet side detected by the second temperature sensor 42 and the heating dehumidification on the air heater outlet side detected by the third temperature sensor 43. and the temperature difference between the detected temperature T ₃ of the air, and the set temperature difference T _SV3 are input. The PID operator 522 performs a PID calculation to generate a control signal based on the temperature difference between the detected temperature T ₂ of the cooling dehumidifying air and the detected temperature T ₃ of the heated dehumidified air, the deviation between the set temperature difference T _SV3 To the inverter control unit 45.

As described above, since the plurality of drying modes include the normal drying mode that takes into account both the drying speed and quality of wood, the range of mode selection is expanded, and the quality or cost required as a product is more optimal. It becomes possible to perform a drying process.
Further, in the usual drying mode, the temperature difference between the detected temperature T ₃ of the detected temperature T ₂ and the heating dehumidified air cooling the dehumidified air is controlled to be constant, a constant amount of heating in air heater 15 held Therefore, stable temperature and humidity adjustment is possible.

FIG. 9 is a diagram for explaining the followability to the drying schedule during the normal drying mode operation, where (A) is a graph showing the set temperature of the drying schedule and the detected temperature in the drying chamber, and (B) is the set humidity of the drying schedule. It is a graph which shows the detected humidity in a drying chamber.
By executing the normal drying control logic described above, the detected temperature and the detected humidity in the drying chamber exhibit a follow-up property as illustrated with respect to the set temperature and the set humidity of the drying schedule. As shown in FIG. 9A, the detected temperature in the drying chamber changes slightly below the set temperature of the drying schedule. On the other hand, as shown in FIG. 5B, the detected humidity in the drying chamber changes slightly below the set humidity of the drying schedule. This is because the temperature and humidity in the drying chamber are controlled so as to be in good balance, whereby it is possible to perform wood drying considering both drying cost and quality.

Moreover, in this embodiment, it is preferable that the drying mode selection means 51 selects a drying mode according to the use or kind of wood.
Here, the effect of the type of wood on the drying process will be described.
In general, wood is broadly divided into conifers and hardwoods.
Conifers such as cedar and cypress have a lower density than hardwoods and dry relatively quickly, so that the amount of distortion due to shrinkage of the wood due to evaporation of moisture is small. Therefore, the drying time is short because cracks and defects during drying are easily suppressed. However, it has a higher water content than hardwood. This water content is the most influential factor when drying conifers. When performing a drying process on wood having a high water content, it is necessary to estimate in advance the amount of water to be removed. Since conifers are less prone to defects in the drying process, the drying temperature can be set relatively high. However, since the water content is high, the amount of evaporated water per unit time in the drying process increases. Therefore, equipment with a high dehumidifying capacity is required, but when it is assumed that the dehumidifying amount exceeds the capacity of the wood drying device, operation is performed according to the drying schedule incorporated in the control device of the wood drying device. It becomes impossible to extend the drying time, resulting in a decrease in efficiency. Therefore, in such a case, the drying time can be shortened by selecting the high-speed drying mode of the present embodiment, and the drying cost can be reduced. Here, as an example, a cedar drying schedule is shown in FIG.

Hardwoods such as white oak are denser than conifers and basically dry slowly. This is because the movement of steam inside the wood is complicated by the structure of the structure. When the temperature is increased to increase the drying speed, the hardwood has a more complicated structure than the softwood and is likely to crack, so that cracks and defects are likely to occur. Thus, hardwood has a low water content but a long drying time. However, since it is dried at a relatively low temperature, it can be said that the amount of mechanical dehumidification is small. However, with regard to humidity adjustment, it is necessary to control the humidity with high precision so as not to cause cracks in the wood. Therefore, by selecting the high-quality drying mode of the present embodiment, it is possible to adjust the humidity with high accuracy, prevent occurrence of defects that occur in the drying process such as cracking, warping, or discoloration, and high-quality dry wood Can be manufactured. As an example, FIG. 10B shows a drying schedule of white oak.
Comparing FIG. 10 (A) and FIG. 10 (B), it can be seen that white oak takes about 2 to 3 times longer to dry the cedar.

  Thus, when selecting the drying mode according to the type of wood, select the high-speed drying mode for drying conifers such as cedar and cypress, and high-quality drying for drying hardwood such as white oak. It is preferable to select a mode. As a result, it is possible to produce high quality dry wood with the shortest drying time corresponding to the wood.

  On the other hand, the performance required for the drying treatment from the use of wood has already been described. However, in wood that requires quality such as furniture and interior materials, defects that occur in the drying process such as cracking, warping, or discoloration. Since it is necessary to dry so as not to occur, high quality drying mode is selected to produce high quality dry wood. On the other hand, for wood that requires low costs such as building materials and structural materials, it is preferable to select a high-speed drying mode to suppress drying costs. As an example, FIG. 11 shows a drying schedule according to the use of wood. FIG. 11 (A) is a diagram showing a drying schedule for interior wood, (B) is a diagram showing a drying schedule for general building materials, and (C) is a diagram showing a drying schedule for general building materials allowing discoloration. is there.

Next, with reference to the flowchart of FIG. 12, the control method of the wood drying apparatus which concerns on embodiment of this invention is demonstrated.
First, as step S1, the control device determines the current operation method of the drying device, and determines whether or not the drying operation is in progress. Here, as the operation method of the drying apparatus, for example, a startup operation in which the temperature in the drying chamber is raised to a predetermined temperature during startup, a drying operation in which the temperature and humidity in the drying chamber is adjusted when drying wood, There is a defrost operation that performs defrosting. At this time, the drying operation may have a plurality of operation methods. These operation methods can be switched depending on how the auxiliary heat exchanger 16 is used in the heat pump 10. For example, in the configuration shown in FIG. 1, by turning on the fan 16a of the auxiliary heat exchanger 16 during the drying operation, the auxiliary heat exchanger 16 functions as an air-cooling heat dissipating means, while the fan 16a is turned off. The auxiliary heat exchanger 16 is caused to function as a part of the refrigerant line. Thereby, it can be set as the different driving | operation system which changed the cooling-heat balance at the time of drying operation. When the drying apparatus is operated by heating, the evaporator 12 is disconnected from the refrigerant line 20 and the refrigerant line 20 is changed so that the auxiliary heat exchanger 16 is interposed between the expansion valve 11 and the internal heat exchanger 13. Further, by turning on the fan 16a of the auxiliary heat exchanger 16, the auxiliary heat exchanger 16 can function as an evaporating means, and the heating operation of the drying apparatus can be performed.

If it is determined that the drying operation is performed in step S1, it is determined in step S2 whether or not the delay time set by the delay timer has elapsed. Here, the control device does not control the next step until a preset delay time elapses. This delay control is performed, for example, to wait until the changing operation is completed when there is a change such as switching of the refrigerant line 20 between step S1 and step S3.
Next, in step S3, the drying mode selection means 51 selects one drying mode from the normal drying mode, the high speed drying mode, and the high quality drying mode.

If the normal drying mode is selected in step S3, in step S4, the detection temperature T ₂ and the air heater outlet side detected by the third temperature sensor 43 of the air heater inlet side cooling dehumidifying air detected by the second temperature sensor 42 The temperature difference with the detected temperature T ₃ of the heated dehumidified air and the set temperature difference T _SV3 are input to the rotation speed calculation means 52. Then, at step S7, it carries out a PID calculation based and the temperature difference between the detected temperature T ₂ of the cooling dehumidifying air and the detected temperature T ₃ of the heated dehumidified air, the deviation between the set temperature difference T _SV3.

Furthermore, in step S8, the rotational speed R _{CS of} the blower 5 is compared with the rotational speed lower limit value R _CSmin and the rotational speed upper limit value R _CSmax , respectively, and the rotational speed R _CS of the blower 5 is _{equal to} or higher than the rotational speed lower limit value R _CSmin and The rotational speed is maintained if the rotational speed upper limit value R _CSmax or less. On the other hand, the rotational speed _{R CS} of the blower 5 is less than the rotational speed lower limit value _{R CSMin,} the rotational speed _{R CS} of the blower 5 increases the number of rotation such that the rotational speed lower limit value _{R CSMin.} On the other hand, the rotational speed _{R CS} of the blower 5 as long as the rotational speed upper limit value _{R CSmax} exceeded, the rotational speed _{R CS} of the blower 5 reduces the number of rotation such that the rotational speed upper limit value _{R CSmax.}

If in step S3 fast drying mode is selected, in step S5, the detected temperature T ₁ of the drying chamber detected by the first temperature sensor 41, an input a first set temperature T _SV1 within the rotation speed calculation means 52 Is done. Then, at step S7, it carries out a PID calculation based on the deviation of the detected temperature _{T 1} of the drying chamber and the first set temperature _{T SV1.} Steps S8 and after are performed in the same procedure as described above.

When the high-quality drying mode is selected in step S3, in step S6, and the detected temperature T ₂ of the cooling dehumidifying air detected air heater inlet side at a second temperature sensor 42, and the second set temperature T _SV2 rotation It is input to the number calculation means 52. Then, in step S7, the temperature _{T 2} of the drying chamber detected by the second temperature sensor 42, performs PID calculation based on the deviation between the second set temperature _{T SV2.} Steps S8 and after are performed in the same procedure as described above.

As described above, according to this embodiment, a drying mode corresponding to a request with the highest priority can be selected from a plurality of drying modes including a high-speed drying mode and a high-quality drying mode. Thereby, it becomes possible to perform optimal drying according to a use, a kind, etc. of wood.
Moreover, since it is set as the structure which controls the rotation speed of an air blower based on drying mode, it becomes possible to finely adjust the temperature and humidity of heating dehumidification air accurately.

Further, as a modification of the present embodiment, when the detected temperature in the drying chamber 1 detected by the first temperature sensor 41 continues to be out of the set temperature range of the drying schedule for a certain time or longer, heating is performed. The temperature setting value of the dehumidified air may be changed.
Here, the temperature of the heated dehumidified air on the outlet side of the air heater is adjusted so that the second controller 61 controls the number of rotations of the compressor 14 to have a preset temperature degree set value. This temperature set value is set in advance so that the drying chamber becomes the set temperature of the drying schedule by the heated dehumidified air.

FIG. 13 is a diagram for explaining a method for changing the temperature setting value of the heated dehumidified air. (A) is a graph showing the set temperature and the detected temperature in the drying chamber, and (B) is a setting before changing the heated dehumidified air. It is a graph which shows temperature and preset temperature after a change.
As shown in FIG. 13 (A), while the time passes t _alpha from time t _1, when the detected temperature of the drying chamber is below always set temperature of the drying schedule, as shown in FIG. 13 (B), at time t ₂ from time t ₁ has elapsed time t _alpha, make changes to increase the temperature setpoint of the heating dehumidified air.
On the other hand, as shown in FIG. 13 (A), while the time passes t _beta from time t _3, when the detected temperature of the drying chamber exceeds at all times the set temperature of the drying schedule, as shown in FIG. 13 (B) to, at time t ₄ when the elapsed time t _beta is from time t _3, make changes to reduce the temperature setpoint of the heating dehumidified air. The time t _α or the time t _β is set in advance.

  As described above, when adjusting the temperature of the heated dehumidified air, the temperature setting value of the heated dehumidified air is changed when the detected temperature in the drying chamber is outside the set temperature range of the drying schedule for a certain period of time or longer. By doing so, it is possible to perform control in consideration of a response delay with respect to the rotational speed control of the blower 5, and it is possible to improve control accuracy.

DESCRIPTION OF SYMBOLS 1 Drying chamber 3 Air line 4 Cooling dehumidifier 10 Heat pump 11 Expansion valve 12 Evaporator 14 Compressor 15 Air heater 16 Auxiliary heat exchanger 20 Refrigerant line 30 Water storage tank 31, 34 Water circulation line 32, 35 Pump 41 First temperature sensor 42 2nd temperature sensor 43 3rd temperature sensor 44 Water temperature sensor 50 1st controller 51 Drying mode selection means 52 Rotational speed calculation means 61 2nd controller 62 3rd controller

Claims (5)

A drying chamber in which wood is stored; a cooling dehumidifier that cools and dehumidifies moisture-containing air exhausted from the drying chamber; an air heater that heats the cooled dehumidified air from the cooling dehumidifier; and an exhaust from the drying chamber An air blower that forms an air flow that is returned to the drying chamber through the cooling dehumidifier and the air heater; A control device for a wood drying device for drying the wood based on a drying schedule including humidity,
A drying mode selection means for selecting one drying mode from a plurality of drying modes including a high-speed drying mode that emphasizes the drying speed of the wood and a high-quality drying mode that emphasizes the quality of the wood;
A control logic is set for each of the plurality of drying modes, and a rotation speed calculation means for calculating the rotation speed of the blower using the control logic corresponding to the drying mode selected by the drying mode selection means ,
Second temperature detecting means for detecting the temperature of the cooling dehumidified air on the air heater inlet side;
With
While controlling the blower to be the rotational speed calculated by the rotational speed calculation means ,
The control logic in the high-quality drying mode controls the rotational speed of the blower so that the detected temperature of the second temperature detecting means becomes a second set temperature set lower than the set temperature in the drying chamber. A control device for a wood drying device, characterized by being configured . A drying chamber in which wood is stored; a cooling dehumidifier that cools and dehumidifies moisture-containing air exhausted from the drying chamber; an air heater that heats the cooled dehumidified air from the cooling dehumidifier; and an exhaust from the drying chamber An air blower that forms an air flow that is returned to the drying chamber through the cooling dehumidifier and the air heater; A control device for a wood drying device for drying the wood based on a drying schedule including humidity,
A drying mode selection means for selecting one drying mode from a plurality of drying modes including a high-speed drying mode that emphasizes the drying speed of the wood and a high-quality drying mode that emphasizes the quality of the wood;
A control logic is set for each of the plurality of drying modes, and a rotation speed calculation means for calculating the rotation speed of the blower using the control logic corresponding to the drying mode selected by the drying mode selection means ,
Second temperature detecting means for detecting the temperature of the cooling dehumidified air on the air heater inlet side;
A third temperature detecting means for detecting the temperature of the heated dehumidified air on the air heater outlet side;
The plurality of drying modes further includes a normal drying mode that takes into account both the drying speed and quality of the wood,
While controlling the blower to be the rotational speed calculated by the rotational speed calculation means ,
The control logic in the normal drying mode is configured so that the temperature difference between the detected temperature of the second temperature detecting means and the detected temperature of the third temperature detecting means becomes a preset temperature difference. A control device for a wood drying device, characterized in that the number of rotations is controlled . First temperature detecting means for detecting the temperature in the drying chamber;
The control logic of the high-speed drying mode is configured to control the rotational speed of the blower so that the detected temperature of the first temperature detecting unit is equal to or higher than a first set temperature set based on the drying schedule. The control apparatus for a wood drying apparatus according to claim 1 or 2 , wherein the control apparatus is a wood drying apparatus. Wherein in the drying mode selection means, the control apparatus of the wood drying apparatus according to any one of claims 1 to 3 wherein the drying mode is being selected depending on the application or type of the timber. First temperature detecting means for detecting the temperature in the drying chamber;
An evaporator for supplying cold to the cooling dehumidifier, a compressor, the air heater, and a heat pump including an expansion valve;
Compressor control means for controlling the number of revolutions of the compressor based on a temperature setting value of the heated dehumidified air on the air heater outlet side,
The temperature set value of the heated dehumidified air is changed when a state in which the temperature detected by the first temperature detecting means is out of the set temperature range of the drying schedule continues for a certain time or longer. Item 5. A control device for a wood drying apparatus according to any one of Items 1 to 4 .

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