JP5102906B2 - Wood drying method - Google Patents

Description

The present invention relates to a method for drying wood that can be dried in a short time and with small energy without impairing the strength, fragrance, and gloss inherent in wood in the field of artificial drying of wood.

Structural materials such as beams and pillars used in houses are required to be sufficiently dry. If the construction is carried out without the structural material being sufficiently dry, mold will form on the structural material during or after the construction, or the wood will shrink during the course of drying, causing floor noise and cracks in the walls. Problems such as cracking of wood are likely to occur.
In the past, the construction period was long enough that the material could be dried during the construction period. However, in recent years, the construction period is shortened, and in the period until the structural material is covered with a roof, a wall, a floor or the like, it is about one to two months after the upper building. During this period, it is difficult to dry the structural material during the construction period.
Also, recently, structural materials have been pre-cut, but if undried materials are used, they will not be applied to the machine due to warping, bending, etc. in the process of waiting for processing, or drying after processing. If the process advances, the processing accuracy will deteriorate, and problems such as inability to assemble correctly will occur.
Furthermore, the “residential property warranty system” under the “Housing Performance Labeling System” of the “Law on Promotion of Housing Quality Assurance”, which came into force in 2000, emphasized “residence for housing defects” and uses undried materials. As a result, large claims are expected, and desiccants are required more.

In the past, the method of drying wood by natural drying cuts standing trees in winter and leaves them on the slopes of the mountains without cutting branches or leaves for 2 to 3 months. The method of lumbering at a lumber mill and drying indoors or outdoors depending on the purpose of use and the tree species was used. The drying period was generally 1 to 3 years, although it varied depending on the location of use and the type of material.
On the other hand, in recent years, the demand for desiccant materials has increased, and research on artificial drying systems has greatly advanced as a method for drying wood in order to increase the drying speed. As an artificial drying system, first, a technology for drying with high-temperature (about 100 ° C) wind was established, but with high-temperature hot air, the drying speed of the wood surface was fast, and the internal drying speed could not catch up with it, so The problem of “cracking” occurred. Therefore, a method has been developed to prevent the “cracking” by warming the wood surface with steam.
After that, dryers using far-infrared rays, high-frequency waves, and microwaves, and dryers using pressurization, decompression and vacuum methods were devised so that heat could be transferred quickly to the inside.
Such a conventional dryer has a relatively large scale, a structure of a steel structure, and an iron plate or a stainless plate attached to the outside or the inside is the mainstream. With artificial drying, it is required to dry a large amount of wood in a short time, and in the drying process under high temperature and high pressure, the floor gets wet or soiled with cell fluid or tar discharged from the wood. Since a large load is applied to the equipment such as, the strength, durability, and corrosion resistance are required. Therefore, the scale is large, and steel and stainless steel are often used.

In order to solve these problems, (Patent Document 1) states that “water vapor supplied by a steam boiler and air supplied by an air blower are silenced by an electromagnetic induction heating device and used as a heat medium in a drying chamber for a short time. And a wood device for homogeneous drying.
In addition, (Patent Document 2) states that “in the drying process of a prism for building material, as a pretreatment of the hot air drying process, the temperature inside the raw wood is increased from 55 ° C. to about 100 ° C. using microwave energy, and After raising the internal pressure of wood, it is sent to a hot-air drying chamber that can be controlled to temperature and humidity, and the moisture of the wood is evaporated from the mouth of the raw wood to dry it as a raw log.
(Patent Document 3) states that “the internal temperature of the raw wood is increased by microwave energy and the internal pressure is increased by raising the internal temperature of the raw wood to 50 ° C. to 100 ° C. and increasing the internal pressure. , A wood drying apparatus composed of a drying room that can control the room at a preset humidity and temperature.
(Patent Document 4) “Wood characterized in that hot air of 80 to 150 ° C. is blown onto wood at a wind speed of 0.1 to 1 m / sec from a duct outlet provided in the upper part of the drying chamber and dried. Is disclosed.
(Patent Document 5) “Wood dryer is equipped with a heating device (heater), humidification device (steamed pipe), blower device (propeller fan), (exhaust heat recovery type) heat exchange device, It is equipped with each sensor that measures the temperature and moisture content of the material with the center, and it is equipped with a control device that controls the temperature and humidity of the atmosphere in the wood dryer room and the transition between processes based on the measured value of each sensor And a “wood drying apparatus”.
(Patent Document 6) states that “a drying chamber in which a ceiling portion, a side wall portion, and a floor portion are formed in a double structure by an outer wall and an inner wall; and a hermetic opening / closing door disposed on the front wall portion of the drying chamber; A heat insulating layer disposed between the outer wall and the inner wall, a dehumidifier disposed on the rear wall side of the drying chamber, an outdoor compressor connected to the dehumidifier, and a drying chamber connected to the drying chamber. An outdoor vacuum pump for deaeration, a rectifying core that is provided with a plurality of air holes and is disposed at predetermined intervals from the ceiling and side walls of the drying chamber, and a ceiling of the drying chamber One or more circulation fans disposed on the inner wall of each of the head and side walls, a cart loaded with living things such as wood to be dried, and moisture taken out from living things such as wood outside the drying chamber connected to a dehumidifier A water intake pipe having a water intake, a temperature sensor for measuring the temperature in the drying chamber, and a humidity sensor for measuring the humidity in the drying chamber , A pressure sensor for measuring the vacuum degree of the drying chamber, the timber organisms dryer ", characterized by comprising a disclosed.

JP 2006-110883 A JP-A-6-180183 JP-A-6-174368 JP-A-11-63823 JP 2002-86407 A JP 2004-306579 A

However, the conventional natural drying and artificial drying methods have the following problems.
(1) In natural drying, since drying takes time, there were problems such as securing a vast storage place and enormous management costs during a long drying period.
(2) In high-temperature steam dryers, the drying speed increases because the temperature is raised to 100 ° C or higher. However, as a result of the high-temperature drying, internal cell fluid and components are also extracted, and the wood surface turns black. There was a problem that the fragrance transpired, the surface hardened, and the strength of the wood deteriorated. In addition, since a high-temperature steam dryer requires a steam generator, the equipment cost is high, and heavy oil is used, so that there is a problem that the fuel cost increases due to an increase in the price of crude oil.
(3) Although there is a high-temperature dryer using biomass power generation, there is a problem in terms of cost effectiveness because the equipment cost is high. Dryers using microwaves require high-output power supply equipment, and work such as suspending materials one by one on hooks was necessary to uniformly apply electromagnetic waves. Therefore, the work efficiency is poor and the cost is increased. In addition, there are problems that the drying chamber becomes dirty due to high temperature, and the finished color changes. In addition, a dryer using microwaves or high frequencies consumes a large amount of electric power during drying, resulting in a problem of high running costs.
(4) Depressurization and vacuum dryers require advanced incidental equipment and a strong dryer body, so that the equipment cost becomes too high, and the cost-effectiveness cannot be increased unless the dryer is large. there were. However, when the apparatus becomes large, not only the construction cost becomes high, but also the construction site is limited, and the transportability and portability are also lowered. As a result, the undried material has to be transported to the place where the dryer is located. However, since the moisture occupies nearly half of the weight of the undried material, there is a problem that the transportation cost becomes high. From a structural point of view, with conventional drying methods, low cost wooden construction of the dryer has problems such as strength, durability, and corrosion resistance, and is also realized in terms of maintenance and cost. It was difficult.

The present invention has been made to solve the above-mentioned problems, and by not increasing the drying temperature, the occurrence of defects such as warping, cracking, shrinkage, and bending of the wood after drying is reduced, and surface gloss and By leaving the scent as it is, the value as a product can be raised, it is excellent in high quality, and in addition to drying at low temperature, the entire dryer is surrounded by a heat insulating layer, so less energy is required, Because natural energy is also used, it is excellent in energy saving and environmental protection, and it is easy to install by making the structure of the main body of the equipment and the internal and external finishing materials, and there is no need for a steam generator or excessive electrical equipment , requires less capital investment, as a whole it is possible to reduce the cost related to the wood drying equipment easily introduced, installation flexibility, wood drying side with wood dryer excellent in mass productivity And an object thereof is to provide a.

In order to solve the above problems, the wood drying method of the present invention has the following configuration.
The wood drying method according to claim 1 of the present invention is a drying chamber in which a ceiling portion, a wall portion, and a floor portion are formed in a double manner by an outer wall and an inner wall, and a heat insulating layer is provided between the outer wall and the inner wall; A temperature control device that heats and cools the wood housed in the drying chamber, an outside air introduction fan that introduces outside air into the drying chamber, and an indoor air discharge fan that discharges the air in the drying chamber to the outside of the drying chamber; , a wood drying method using a wood dryer equipped with, and repeating alternately cooling and heating of wood by the regulating device, the temperature of the drying chamber at the time of heating the timber by the temperature adjustment device However, the temperature is 60 to 35 ° C., and the temperature in the drying chamber when the wood is cooled by the temperature adjusting device is 10 to 0 ° C.
This configuration has the following effects.
(1) A drying room in which the ceiling, wall, and floor are doubled by the outer wall and the inner wall and having a heat insulating layer between the outer wall and the inner wall, and the temperature at which the wood stored in the drying room is heated and cooled By using a wood dryer provided with an adjusting device, it is difficult to be influenced by the external temperature and humidity environment, the drying chamber can be stably maintained at a desired temperature, and energy saving is excellent.
(2) By alternately repeating heating and cooling of the wood with the temperature control device, the transpiration speed from the wood surface after heating is reduced, the difference in moisture content between the wood surface portion and the wood interior is reduced, and the whole wood is It can be dried gradually and uniformly to prevent cracking and warping, and the wood after drying is excellent in homogeneity and high quality.
(3) The temperature in the drying chamber when the wood is heated by the temperature adjusting device is 60 ° C. to 35 ° C., and the temperature in the drying chamber when the wood is cooled by the temperature adjusting device is 10 ° C. to 0 ° C. Therefore, the wood is not exposed to high temperatures, so there are few defects such as warping, cracking, shrinkage and bending of the wood after drying, and the gloss and fragrance of the surface remain as it is, and drying with high value as a product Wood can be obtained, which is excellent in practicality and reliability.

Here, a hermetic door is provided at the entrance of the drying chamber. However, as with the ceiling, wall, and floor of the drying chamber, heat insulation is provided for the entire drying chamber by using an insulating material. The effect is excellent, the temperature in the drying chamber can be stably maintained, and the energy saving property can be improved. The open / close door may be a single door, a double door (viewing door), or a sliding door type.
In the wood drying process, moisture is evaporated from the surface of the wood into the air by warming the wood, and the moisture inside the wood moves to the surface to keep the moisture in balance with the surface of the wood. Advances. At this time, if the temperature for warming the wood is too high or if only the surface is suddenly warmed in a short time, the movement of moisture from the inside of the wood will not catch up with the transpiration from the wood surface, It is known that there is a difference in moisture content from the inside of the wood, and if this difference becomes too large, the wood will crack or warp.
The wood dryer of the present invention includes a temperature adjusting device that heats and cools wood, and after warming (heating) the wood for a desired period, it stops heating and cools the wood. By setting this cooling period, the amount of saturated water vapor in the air in the drying chamber decreases, and the drying of the air in the drying chamber progresses over time, taking moisture away from the wood surface. Since it is low, there is little transpiration of moisture from the wood surface, and the difference in moisture content between the wood interior and the wood surface is reduced and equalized.
Therefore, by proceeding with drying while alternately repeating heating (warming) and cooling for a predetermined time, the uneven moisture content on the surface and inside of the wood is eliminated, and cracking and cracking of the wood during the drying process are prevented. However, uniform drying can be effectively promoted.

The temperature adjusting device may be any device that can selectively heat and cool wood. Therefore, one unit may have both heating and cooling functions, such as an air conditioner and a fan coil unit, or a heater and a cooler may be provided separately. As the heater, an electric heater such as a sheathed heater, a heat source such as a radiator and a blower combined with a blower, a warm air fan such as a hot air fan, or the like can be used. As the cooler, a cooler such as a radiator and a blower that are combined to blow cool air, a cooler that blows cool air such as a cool air fan, and the like can be used.
The temperature in the drying chamber during the period of warming (heating) the wood is preferably in the range of 60 ° C to 35 ° C. Further, the temperature in the drying chamber during the period of cooling the wood is preferably in the range of 10 ° C to 0 ° C.
As the temperature when warming wood rises above 60 ° C, essential oils and tars ooze out of the wood, causing discoloration of the dried wood, loss of luster, and weakening of the quality. It tends to decrease, and as the temperature is lower than 35 ° C., the transpiration of moisture from the surface of the wood is reduced and it takes time to dry, and the efficiency of drying tends to decrease, Neither is preferred.
In addition, as the temperature when cooling the wood rises above 10 ° C, the difference from the temperature when warming becomes smaller, the transpiration rate of moisture from the wood surface is less likely to drop, and the moisture inside the wood is transferred to the wood surface. Insufficient movement is likely to reduce the uniformity of drying, and only the temperature of the wood surface rises, increasing the temperature difference from the inside, causing distortion inside the wood and causing cracks and warping. As the temperature becomes lower than 0 ° C., the surface of the wood tends to freeze, and it takes time from the start of the warming period of the next process to the desired temperature, and the drying time becomes longer. There is a tendency that the efficiency and energy-saving property are likely to decrease, both of which are not preferable.
The wood dryer used in the wood drying method of the present invention performs processing at a low temperature and under one atmospheric pressure, so the equipment is not excessive compared to conventional high-temperature steam dryers, etc., and is excellent in mass productivity and installation flexibility. In addition, since the energy required for the drying process is small, it is excellent in energy saving and environmental protection.

Invention of Claim 2 is the wood drying method of Claim 1, Comprising : It is equal to the temperature in the said drying chamber by the said external air introduction fan at the time of the heating start by the said temperature control apparatus or in the middle of the heating. While introducing the above warm outside air, the indoor air discharge fan discharges the air in the drying chamber to the outside of the drying chamber, and the outside air introduction fan introduces the air into the drying chamber at the start of cooling by the temperature adjusting device or during cooling. A configuration is adopted in which cool outside air having a temperature equal to or lower than the temperature in the drying chamber is introduced and the air in the drying chamber is discharged out of the drying chamber by the indoor air discharge fan.
With this configuration, in addition to the operation of the first aspect, the following operation is provided.
(1) and the outside air introducing fan for introducing outside air into the drying chamber, the air in the drying chamber with a timber dryer Ru having an indoor air discharge fan for discharging to the outside of the drying chamber, the heating start or heating by temperature adjustment device In the middle, the outside air introduction fan introduces warm outside air equal to or higher than the temperature in the drying chamber into the drying chamber, and the indoor air discharge fan exhausts the air in the drying chamber to the outside of the drying chamber, thereby effectively using the outside air. Since the drying chamber can be warmed, the input energy required for heating can be reduced, and energy saving and heating efficiency are excellent.
(2) and the outside air introducing fan for introducing outside air into the drying chamber, the air in the drying chamber with a timber dryer Ru having an indoor air discharge fan for discharging to the outside of the drying chamber, the cooling start or cooled by the temperature adjustment device In the middle, the outside air introduction fan introduces cool outside air equal to or lower than the temperature in the drying chamber into the drying chamber, and the indoor air discharge fan exhausts the air in the drying chamber outside the drying chamber, thereby effectively using the outside air. In addition, since the drying chamber can be cooled, the input energy necessary for cooling can be reduced, and energy saving and cooling efficiency are excellent.
(3) After a predetermined heating (warming) period is maintained by the temperature adjusting device, cold outside air equal to or lower than the temperature in the drying chamber is introduced into the drying chamber by the outside air introduction fan at the start of cooling, and by the indoor air discharge fan. By exhausting the air in the drying chamber out of the drying chamber, moisture in the drying chamber can be sent to the outside, so that the preparation for the cooling period of the next process can be performed quickly and quickly, and the efficiency of operation Excellent in properties.

Here, each period (hour) of the process of heating (warming), cooling, and introduction of outside air is appropriately selected according to the type of wood, the elapsed time after cutting the wood, the moisture content at the time of carrying into the drying chamber, and the like. Can be combined.
In particular, the four steps of heating (warming), introduction of outside air, cooling, and outside air intake are defined as one cycle, and those that repeat this cycle are preferably used. At this time, it is possible to reduce energy to be input to the next cooling step by setting a cycle so that the outside air is introduced during the transition from heating (warming) to cooling when the outside air temperature is low. In addition, it is possible to reduce the energy input to the next heating (warming) step by setting a cycle so that the outside air is introduced during the transition from cooling to heating (warming) when the outside air temperature is high. it can.
In addition, not only at the time of cooling start (after completion of heating) and at the start of heating (after completion of cooling), but also by introducing outside air during heating or cooling, a method of proceeding drying while using natural energy together The energy required for drying can be further reduced, and energy saving and environmental protection are excellent.

If there is a difference in the volume per piece of wood to be dried, such as a beam material and a plate material, a difference occurs in the amount of latent heat, which greatly affects the energy for raising and lowering the temperature in the drying chamber. In the present invention, since the maximum value of the energy generated by the temperature control device (heating and cooling output) is determined, the cycle time setting and number of times are appropriately changed depending on the moisture content at the time of carry-in, the size of the wood, the shape, etc. It is preferable to do. In addition, the cycle time setting and number of times vary depending on the season temperature and rainfall conditions of the dryer installation location. Also, the high temperature in summer, the low temperature in winter, hot air during the day, even at night It is desirable to change in consideration of the cold air and the humidity of the outside air.
In one cycle, it is desirable that the warming (heating) period and the cooling period are each in the range of 10 hours to 24 hours. The standard time setting for one cycle is 10 hours heating, 2 hours outside air introduction, 10 hours cooling, 2 hours outside air introduction, but is not limited thereto. In particular, in the early stage of drying, in the case of a material having a large moisture content of wood, one cycle can be set to 24 hours or more. In addition, by changing (adjusting) the time of one cycle according to the progress of the drying (advance status), such as shortening the time of one cycle at the beginning of drying and lengthening the time of one cycle near the end, Drying can be performed.

Invention of Claim 3 is the wood drying method of Claim 2 , Comprising: (a) Heating by the said temperature control apparatus, (b) The said external air introduction | transduction at the time of the heating start by the said temperature control apparatus or in the middle of heating Introducing outside air into the drying chamber with warm air equal to or higher than the temperature in the drying chamber by a fan and exhausting the air in the drying chamber to the outside of the drying chamber by the indoor air discharge fan, (c) adjusting the temperature (D) Cooling by the outside air introduction fan is introduced into the drying chamber by the outside air introduction fan at the start or during cooling by the temperature adjusting device, and the outside air discharge fan introduces cold outside air equal to or less than the temperature in the drying chamber. Four cycles of outside air suction for discharging the air in the drying chamber out of the drying chamber are defined as one cycle, and this cycle is performed until the wood has a target moisture content. Is repeated .
With this configuration, in addition to the operation of the second aspect , the following operation is provided.
(1) The four steps of heating (warming), outside air introduction, cooling, and outside air suction are defined as one cycle. When this cycle is repeated, the outside air introduction timing during the transition from heating (warming) to cooling is By setting the cycle to be performed at a low time, the energy input to the next cooling step can be reduced. In addition, it is possible to reduce the energy input to the next heating (warming) step by setting a cycle so that the outside air is introduced during the transition from cooling to heating (warming) when the outside air temperature is high. it can.
(2) A method of promoting drying while using natural energy together by introducing outside air not only at the start of cooling (after completion of heating) or at the start of heating (after completion of cooling), but also during heating or cooling. The energy required for drying can be further reduced, and energy saving and environmental protection are excellent.

Here, when the temperature adjusting device has a heat source, a cold heat source, and an air circulation fan that blows air to the heat source and the cold heat source, a period for warming the drying chamber only by switching on and off the heat source and the cold heat source. The cooling period can be set easily, and it is excellent in operability and controllability. As the heat source and the cold source, one that is switched on and off by a switch installed in the control panel of the wood dryer is preferably used. Moreover, the number and arrangement | positioning of a heat source and a cold heat source can be selected suitably. A temperature sensor is provided inside the drying chamber, and the temperature inside the drying chamber can be accurately controlled by switching on / off of the heat source and cooling source based on the signal from the temperature sensor. Excellent in reliability and reliability. The number and arrangement of the temperature sensors can be selected as appropriate, and can be attached to the hot and cold sources.
The number and arrangement of the air circulation fans can be appropriately selected according to the number, size, and arrangement of the heat source and the cold source, but by arranging the air circulation fan at the rear of the hot source and the cold source, Cold air can be generated and sent into the drying chamber to adjust the temperature in the drying chamber. Note that the air circulation fan can always be operated to circulate the air in the drying chamber.
In the case of having a dehumidifier, the moisture in the drying chamber can be removed to accelerate drying, and the drying efficiency is excellent. The dehumidifier can be switched on and off according to the humidity in the drying room. However, if the dehumidifier always operates during the operation of the wood dryer (during the wood drying period), it is easy to control and easy to handle. Excellent dehumidification reliability.

Drying chamber timber dryer, if it has a lower ceiling disposed at a ceiling portion and a distance below the ceiling, can be used between the ceiling and the lower ceiling as an installation space for such electric wiring Therefore, it is possible to efficiently use the inside of the drying chamber and efficiently store the wood, and the usability and the efficiency of the drying operation are excellent.
Further, the heat source temperature adjustment device, a cold source, the air circulation fan, when it is disposed between the ceiling portion and the lower ceiling, the space of the drying chamber can be effectively used, even air circulation It is useful, can accelerate drying, and is excellent in drying efficiency and energy saving.

Here, the required number of air circulation fans can be determined according to the size of the drying chamber and the heat and cold sources. Air can be sent with one air circulation fan to multiple heat sources and cold sources, but by placing one air circulation fan at the rear of the heat source and cold source as described above, Warm air and cold air can be reliably generated and can efficiently flow into the entire drying chamber without any spots. Note that it is an appropriate arrangement method of the air circulation fans to blow the wind at right angles to the length direction of the wood. This is because when wind is applied parallel to the length direction of the wood, moisture is rapidly lost from the mouth, and the central portion in the length direction cannot be sufficiently dried, resulting in uneven drying.
For example, when 6m long wood is dried, the length of the drying chamber should be about 6.5 to 7.0m. In that case, the number of air circulation fans should be 4 to 8. Is desirable. As the number of air circulation fans becomes smaller than 4, the air volume becomes weaker, the air circulation amount tends to be insufficient, and the drying efficiency tends to decrease, and as the number becomes larger, the arrangement becomes difficult. At the same time, energy consumption tends to increase, which is not preferable.
Also, when using an air circulation fan, attach a control device that can adjust the air volume.If the moisture content in the initial stage of drying is high, increase the air volume.If the air volume is too high, It can be adjusted to the air volume and is excellent in driving efficiency and versatility. As the type of the air circulation fan, what is called a pressure ventilation fan is effective in a sealed space such as a drying room. The air circulation fan preferably has a blade diameter of 25 to 30 cm and an air volume of 1,000 to 1,500 CMH, although it varies depending on the size of the drying chamber.

If having a fan for wood dryer agitates the air in the drying chamber, stirring the air in the drying chamber to reduce the deviation of the temperature and humidity of the entire drying chamber, the air in the drying chamber warmed plaque and efficiently Can be cooled, so that the atmosphere surrounding the wood can be in an even state, the moisture transpiration of individual wood can be kept even, there is little variation in quality after drying, the uniformity of drying, Excellent efficiency.
Also, if having a temperature and humidity measuring instrument timber dryer to measure the temperature and humidity of the drying chamber, is always dry chamber state (temperature and humidity) can be monitored, the drying chamber a desired temperature, to ensure the humidity It can be maintained and has excellent operational stability and certainty.

Here, the number, size, and arrangement of the fans can be appropriately selected according to the size, shape, etc. of the drying chamber. For example, it is preferable to arrange about 4 to 10 fans for a drying chamber having a length of 6.5 m. As with the above-described air circulation fan, the electric fan can supply an appropriate air volume by attaching a control device capable of adjusting the air volume, and is excellent in versatility. In particular, it is preferable to adjust the air volume according to the amount and type of wood. The size of the electric fan is preferably in the range of a blade diameter of 30 to 60 cm and an air volume of 1,500 to 4,000 CMH.
The fan is preferably capable of adjusting the wind direction by the swing function, but it is desirable that the air blowing direction (wind direction) is such that the wind hits from the side of the wood and the wind is not applied to the mouth. As described above, this is to prevent the rapid drying from the mouth.
The number and arrangement of thermo-hygrometers can be selected as appropriate, but it is preferable to attach them at a plurality of locations in the drying chamber. This is because the air volume and direction are adjusted in accordance with the temperature and humidity distribution in the drying chamber to uniformly dry the wood. Depending on the size of the drying chamber, about 4 to 8 locations are preferred.

Drying chamber, when a wooden building, is easy to feed and the design, processing and assembly of building materials, it is possible to suppress construction cost low, is excellent in mass productivity.
Also, if the drying chamber has a wooden building, it is possible to reduce the size as compared with a dryer of a conventional vacuum system or a vacuum system, it can be placed in such relatively close mountains from felling site It is excellent in installation flexibility, can increase the utilization, and can improve the productivity of dry wood.
Here, as a timber for use in the production of drying chamber, by using a timber produced in the vicinity of the installation location of the timber dryer can achieve local consumption, compared to metal, energy saving at the time of manufacture Excellent.

According to invention of Claim 1, it has the following effects.
(1) By reducing the difference in moisture content between the wood surface and the inside of the wood during the drying process, the whole wood can be gradually and uniformly dried to prevent cracking and warping. In addition, it is possible to provide a wood drying method with excellent high quality.
(2) Obtaining dry wood that is not exposed to high temperatures, has few defects such as warping, cracking, shrinkage and bending of the wood after drying, remains glossy and scented on the surface, and has high value as a product Therefore, it is possible to provide a method for drying wood that is practical and reliable.

According to invention of Claim 2, in addition to the effect of Claim 1, it has the following effects.
(1) Wood drying with excellent energy efficiency and cooling efficiency, which can effectively use the outside air to warm or cool the drying chamber and reduce the input energy required for heating and cooling. A method can be provided.

According to invention of Claim 3, in addition to the effect of Claim 2 , it has the following effects.
(1) By setting a cycle so that the period of outside air introduction during the transition from heating (warming) to cooling is performed when the outside air temperature is low, energy input to the next cooling step can be reduced. In addition, it is possible to reduce the energy input to the next heating (warming) step by setting a cycle so that the outside air is introduced during the transition from cooling to heating (warming) when the outside air temperature is high. it can.

Cross-sectional plan view of the main part of the wood dryer used in the wood drying method of the first embodiment Cross-sectional side view of main part of wood dryer used for wood drying method of embodiment 1 Cross-sectional front view of the main part showing the accommodation state of the wood and the circulation of air in the drying chamber of the wood dryer used in the wood drying method of the first embodiment Cross-sectional side view of the main part showing the state of accommodation of wood in the drying chamber of the wood dryer used in the wood drying method of Embodiment 1 The figure which shows an example of the operation plan of the wood dryer used for the wood drying method of Embodiment 1, and the operation cycle of each apparatus. Cross-sectional front view of the main part showing the circulation of air in the drying chamber of the wood dryer used in the wood drying method of the second embodiment Cross-sectional front view of main parts showing the state of accommodation of wood in the drying chamber of the wood dryer used in the wood drying method of Embodiment 3

(Embodiment 1)
A wood dryer used in the wood drying method of Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional plan view of the main part of a wood dryer used in the wood drying method of Embodiment 1, and FIG. 2 is a cross-sectional side view of the main part of the wood dryer used in the wood drying method of Embodiment 1. FIG. 3 is a cross-sectional front view of an essential part showing the state of accommodation of the wood and the circulation of air in the drying chamber of the wood dryer used in the wood drying method of Embodiment 1, and FIG. 4 shows the wood drying method of Embodiment 1. It is a principal part cross-sectional side view which shows the accommodation state of the wood in the drying chamber of the used wood dryer.
1 and 2, reference numeral 1 denotes a wood dryer used in the wood drying method according to the first embodiment. Reference numeral 2 denotes a wood dryer in which a ceiling portion 2b, a wall portion 2c, and a floor portion 2d are doubled by an outer wall and an inner wall. Reference numeral 1 denotes a drying chamber, 2a denotes a double door opening / closing door disposed at a front entrance of the drying chamber 2, and 3 denotes a heat insulating layer formed between the outer wall and the inner wall of the ceiling portion 2b, the wall portion 2c, and the floor portion 2d. 4 is a dehumidifier of the wood dryer 1 disposed on one side of the drying chamber 2, and 5 is a temperature control device for the wood dryer 1 disposed between the ceiling portion 2b and the lower ceiling 11 described later. 5a is a heat source of the temperature adjustment device 5 using an electric heater such as a sheathed heater, 5b is a cold heat source of the temperature adjustment device 5 arranged alternately with the heat source 5a, and 6 is from the rear to the heat source 5a and the cold heat source 5b. The air circulation fan 10 of the temperature adjusting device 5 that blows air stands at an important point in the left and right longitudinal directions of the drying chamber 2 with an interval. The pillars 11 and 11 are supported by the pillars 10 and are arranged below the ceiling part 2b with a space from the ceiling part 10 and spaced from the ceiling part 10, and 12 are arranged on both sides of the upper part of the front side of the drying room 2. Outside air introduction fans 13 for introducing outside air into the interior, 13 are indoor air exhaust fans that are disposed on both sides of the upper part on the rear side of the drying chamber 2 and exhaust the air in the drying chamber 2 to the outside, and 15a and 15b are a ceiling portion 2b and a lower portion It is an air passage formed between the ceilings 11 and on both sides of the drying chamber 2.

In the figure, the drying chamber 2 of the wood dryer 1 was generally produced with a height of 3.0 m, a frontage of 3.0 m, and a length of 7.0 m. As design conditions, height and frontage are factors determined by the amount of drying per operation for each office. On the other hand, considering the length of the wood (3.0m, 4.0m, 6.0m), in addition to the maximum dimension of 6.0m, some length is required for the length. For this reason, this embodiment is set to 7.0 m. When the height of the drying chamber 2 is extremely low with respect to the frontage dimension, the loaded state of the material becomes wider and the air may not reach the middle part of the material to be dried. Therefore, the ratio between the frontage and the height is appropriately 1: 1 to 1: 2.
A heat insulating material such as glass wool or urethane is preferably used for the heat insulating layer 3. After constructing the heat insulating material, if it is covered with an airtight holding material such as a vinyl sheet and the airtightness in the drying chamber 2 is increased, the heat insulating performance is further improved. This method can utilize the technique of a highly insulated and airtight house. The heat insulation layer 3 is provided in the drying chamber 2 whole (ceiling part 2b, wall part 2c, floor part 2d). Moreover, the heat insulating layer 3 is provided also in the opening / closing door 2a, and is excellent in the heat insulation effect similarly to the heat insulating layer 3 of the drying chamber 2 main body, and functions to keep the temperature in the drying chamber 2 stably with energy saving. The open / close door 2a is not limited to double doors, but may be a sliding door type.

In general, there are two methods for carrying the material into the drying chamber 2: a method using a narrow entrance as a carry-in entrance and a method using a wide entrance as a carry-in entrance. The method of carrying in from a narrow frontage is suitable for the drying chamber 2 having a small size. In the case of this method, a method in which a material is placed on a carriage or the like and pushed into the drying chamber 2 is preferably used. On the other hand, in the method of carrying in from a wide frontage, it is possible to carry in the material sideways using a forklift or the like. This method is suitable for the drying chamber 2 having a relatively large scale.
In the wood dryer 1 used in the wood drying method of the present embodiment, the volume of the material that can be dried at one time is approximately 20 to 25 cubic meters although it depends on the size of the material. This volume, floor area 100m ² ~150m ² about wooden house, corresponding to the required amount of structural material about 1-2 buildings min. In addition, the size of the wood dryer 1 is not limited to this Embodiment, A design can be performed according to the installation place and the situation for every establishment.

In the wood dryer 1 used in the wood drying method of the present embodiment, the drying chamber 2 is made of wood. All members such as structural materials, wall finishing materials, floor materials, and outer walls may be made of wood, or only the structural materials may be steel frames. Unlike the high-temperature steam drying, the wood dryer 1 used in the wood drying method of the present invention has a small generated pressure in the drying chamber 2 and a small amount of extraction of wood tar components and the like. Therefore, the strength can be small, and there is little risk of getting dirty, so it is possible to make the wood low in cost. In addition, most of the generated water is discharged by the dehumidifier 4. Finishing materials such as the ceiling part 2b, the wall part 2c, and the floor part 2d may be peeled wood or plywood.

By disposing the hot heat source 5a, the cold heat source 5b, and the air circulation fan 6 between the ceiling 2b and the lower ceiling 11, there is no protrusion of machinery in the drying chamber 2, and the safety and efficiency of work are improved. . Moreover, the installation location of the opening used for carrying in the wood can be freely set.
Since the air passages 15 a and 15 b are formed between the ceiling portion 2 b and the lower ceiling 11 and on both sides of the drying chamber 2, the air sent from the heat source 5 a or the cold source 5 b is dried by the air circulation fan 6. It is efficiently sent into the chamber 2.
In addition, in this Embodiment, it was set as the structure which supports the lower ceiling 11 with the pillar 10, However, The attachment method of the lower ceiling 11 is not limited to this, You may suspend from the ceiling part 2b.

The usage method of the wood dryer used for the wood drying method of Embodiment 1 comprised as mentioned above is demonstrated.
3 and 4, 20 is a carriage for transporting and storing the wood 25 to be dried in a state of being stacked in the drying chamber 2, 26 is a carrier for loading the wood 25 at intervals, and 27 is a wood 25 and wood. 25 is an air passage formed between 25.
In the drying process, when the amount of the wood 25 is remarkably large, or when the wood 25 is not loaded in an orderly manner, it is difficult to wind the wood 25 evenly, which is not preferable.
In the present embodiment, as shown in FIGS. 3 and 4, when the timbers 25 are arranged, a gap is secured by sandwiching the piers 26 between the timbers 25 and 25 in both the vertical and horizontal directions. The gap is preferably 30 mm to 50 mm. Thereby, the wind path 27 can be ensured between the timber 25 and the timber 25, and the wind can easily pass to the central portion, so that all the timber 25 can be uniformly dried without spots.
In the drying process, it is desirable to arrange the material so that the wind hits from the side of the wood 25, and a method in which the wind hits from the mouth is not preferable. This is because cracks may occur in the wood 25 when the wind is struck significantly in the direction of the mouth. Therefore, it is desirable to adjust the direction of the wind generated by the air circulation fan 6.
In the present embodiment, the timber 25 is carried in using the trolley 20, but the trolley 20 is not necessarily required. When the carriage 20 is not used, a forklift may be used or it may be transported manually.

FIG. 5 is a diagram showing an example of an operation plan of a wood dryer used in the wood drying method of Embodiment 1 and an operation cycle of each device.
In FIG. 5, 30 is a graph showing the temperature in the drying chamber 2, 31 is a graph showing the outside air temperature, 32 is an operating state of the heat source, 33 is an operating state of the cold source, and 34 is an operation of the outside air introduction fan. The figure which shows a state, 35 is a figure which shows the operating state of an indoor air exhaust fan, 36 is a figure which shows the operating state of an air circulation fan, 37 is a figure which shows the operating state of a dehumidifier.
In FIG. 5, the temperature 30 at the time of drying is changed in the range of 60 ° C. to 0 ° C. Within this set temperature, the drying chamber 2 is continuously dried until the desired moisture content is reached while repeating the warming period and the cooling period. This operation time is controlled by a timer connected to each device.
The moisture content of the target material is 20% or less, preferably 18% or less.
The time axis (horizontal axis) in FIG. 5 shows one cycle of 24 hours and 48 hours for two cycles, but this is repeated for the required time until the material has a desired moisture content. The usage days of the wood dryer 1 vary depending on the tree species, the moisture content of the material at the time of carrying in the dryer, the size of the material, etc. Generally, if the plate material is about 60 mm thick, the size is 120 × for approximately 7 days. With a beam material of 360 mm and an initial moisture content of about 30%, the target moisture content can be obtained in approximately 10 to 20 days. However, depending on the type of material, the initial moisture content, and the site, it may be necessary for 20 days or more to reach the desired moisture content.
Therefore, during drying, the moisture content of the wood 25 is measured periodically, drying is performed while confirming the dry state, and the drying is finished when the desired moisture content is reached.

The operation plan in FIG. 5 shows a standard drying process in which one cycle is 24 hours and is repeated. In the actual operation of the wood dryer 1, a method is adopted in which one cycle is set to 36 hours, 48 hours, or an arbitrary time depending on the tree species, moisture content, and temperature of the outside air. Furthermore, a method of adopting a 48-hour cycle only at the initial stage of drying with a high water content, and then changing to 36 hours, 24 hours or an arbitrary time to make a cycle of a short time step by step.
In FIG. 5, the nighttime and daytime temperatures fluctuate as indicated by 31 lines representing the outside air temperature. Considering the relationship with this temperature, the cycle is set to match the outside air introduction time. Although it depends on the installation location, the standard set maximum temperature of 60 ° C. is slightly higher than the summer daytime temperature, and the standard set minimum temperature of 0 ° C. is close to the winter night temperature. When switching to the warming period, warm outside air is taken in, and when switching to the cooling period, cold outside air is actively taken in, so that energy saving can be further improved. In mountainous areas, it is expected to be 0 ° C. or less at night, and introduction of outside air at the initial stage of cooling is more effective.

  In FIG. 5, the operation time of the outdoor air introduction fan 34 and the operation state of the indoor air discharge fan 35 are set to 2 hours, but the wood dryer 1 is installed. The energy saving cycle is set by shortening or extending as appropriate according to the temperature distribution and environmental conditions of the area. In winter, the operating state 34 of the outside air introduction fan may be in the ON state for the same time as the cold source operating period (see 33 showing the cold source operating state). The outside air introduction fan 12 and the indoor air discharge fan 13 are linked to each other, and the operation time can be set by a timer or a temperature sensor. It is preferable to actively use hot air in the daytime in summer and cold air in the nighttime in winter, and it is desirable to set the operation time after investigating the weather conditions at the installation site.

The wood drying method using the wood dryer in Embodiment 1 has the following effects.
(1) A drying room in which the ceiling, wall, and floor are doubled by the outer wall and the inner wall and having a heat insulating layer between the outer wall and the inner wall, and the temperature at which the wood stored in the drying room is heated and cooled By providing the adjustment device, it is difficult to be influenced by the external temperature and humidity environment, the drying chamber can be stably maintained at a desired temperature, and energy saving is excellent.
(2) By alternately repeating heating and cooling of the wood with the temperature control device, the transpiration speed from the wood surface after heating is reduced, the difference in moisture content between the wood surface portion and the wood interior is reduced, and the whole wood is It can be dried gradually and uniformly to prevent cracking and warping, and the wood after drying is excellent in homogeneity and high quality.
(3) and the outside air introducing fan for introducing outside air into the drying chamber, the air in the drying chamber with a timber dryer Ru having an indoor air discharge fan for discharging to the outside of the drying chamber, the heating start or heating by temperature adjustment device In the middle, the outside air introduction fan introduces warm outside air equal to or higher than the temperature in the drying chamber into the drying chamber, and the indoor air discharge fan exhausts the air in the drying chamber to the outside of the drying chamber, thereby effectively using the outside air. Since the drying chamber can be warmed, the input energy required for heating can be reduced, and energy saving and heating efficiency are excellent.
(4) and the outside air introducing fan for introducing outside air into the drying chamber, the air in the drying chamber with a timber dryer Ru having an indoor air discharge fan for discharging to the outside of the drying chamber, the cooling start or cooled by the temperature adjustment device In the middle, the outside air introduction fan introduces cool outside air equal to or lower than the temperature in the drying chamber into the drying chamber, and the indoor air discharge fan exhausts the air in the drying chamber outside the drying chamber, thereby effectively using the outside air. In addition, since the drying chamber can be cooled, the input energy necessary for cooling can be reduced, and energy saving and cooling efficiency are excellent.
(5) After a predetermined heating (warming) period is maintained by the temperature adjusting device, cool outside air having a temperature equal to or lower than the temperature in the drying chamber is introduced into the drying chamber by the outside air introduction fan at the start of cooling, and by the indoor air discharge fan. By exhausting the air in the drying chamber out of the drying chamber, moisture in the drying chamber can be sent to the outside, so that the preparation for the cooling period of the next process can be performed quickly and quickly, and the efficiency of operation Excellent in properties.
(6) Since the temperature adjusting device of the wood dryer has a heat source, a cold heat source, and an air circulation fan that blows air to the heat source and the cold heat source, drying can be performed simply by switching on and off the heat source and the cold heat source. The period for warming the room and the period for cooling can be easily set, and the operability and the ease of control are excellent.
(7) When the wood dryer has a dehumidifier, the moisture in the drying chamber can be removed and drying can be promoted, and the drying efficiency is excellent.
(8) The drying room of the wood dryer has a lower ceiling arranged at a distance from the ceiling below the ceiling, so that the space between the ceiling and the lower ceiling is used as an installation space for electrical wiring, etc. Therefore, it is possible to efficiently use the inside of the drying chamber and efficiently store the wood, which is excellent in usability and efficiency of the drying operation.
(9) The space in the drying chamber can be effectively used by arranging the heat source, the cold source and the air circulation fan of the temperature control device of the wood dryer between the ceiling and the lower ceiling. It is also useful for air circulation, can promote drying, and is excellent in drying efficiency and energy saving.
(10) Since the drying room of the wood dryer is a wooden building, the supply of building materials and the design, processing, and assembly are easy, the construction cost can be kept low, and the mass productivity is excellent.
(11) By making the drying room of the wood dryer a wooden building, the scale can be reduced compared to conventional decompression and vacuum drying machines, and even in mountainous areas that are relatively close to the logging site. It can be installed, has excellent installation flexibility, can be used more efficiently, and can improve the productivity of dry wood.
(12) The temperature in the drying chamber when the wood is heated by the temperature adjusting device is 60 ° C. to 35 ° C., and the temperature in the drying chamber when the wood is cooled by the temperature adjusting device is 10 ° C. to 0 ° C. Therefore, the wood is not exposed to high temperatures, so there are few defects such as warping, cracking, shrinkage and bending of the wood after drying, and the gloss and fragrance of the surface remain as it is, and drying with high value as a product Wood can be obtained, which is excellent in practicality and reliability.

(Embodiment 2)
The wood dryer used for the wood drying method in Embodiment 2 of this invention is demonstrated referring drawings below. In addition, the same code | symbol is attached | subjected to the thing similar to Embodiment 1, and description is abbreviate | omitted.
FIG. 6 is a cross-sectional front view of an essential part showing air circulation in a drying chamber of a wood dryer used in the wood drying method of the second embodiment.
In FIG. 6, the wood dryer 1A used in the wood drying method in the second embodiment is different from the first embodiment in that the boiler 7 connected to the heat source 5a using the radiator and the cold heat source 5b using the radiator are used. It is the point provided with the outdoor unit 8 connected to.
The boiler 7 and the outdoor unit 8 are installed outside the drying chamber 2, and send a heat medium or a refrigerant to the hot heat source 5a or the cold heat source 5b.

When the inside of the drying chamber 2 is desired to be warmed, hot water boiled by the boiler 7 is sent to the heat source 5a and the air circulation fan 6 disposed at the rear thereof is operated to send out hot air. At the beginning of the warming period, the outside air introduction fan 12 and the air discharge fan 13 are operated to use natural energy.
The heat source 5a is not limited to the radiator, and a fan coil unit type may be used, or a metal pipe or the like may be used to circulate hot water.
When the inside of the drying chamber 2 is desired to be cooled, the refrigerant is circulated from the outdoor unit 8 and air is sent from the air circulation fan 6 at the rear of the cold heat source 5b to generate cold air. Even in the initial period of the cooling period, the outside air introduction fan 12 and the air discharge fan 13 can be operated. The cooling heat source 5b is not limited to a radiator, and a type in which a fan coil unit, a metal pipe, or the like is piped and a refrigerant is circulated may be used.

According to the wood dryer used for the wood drying method in Embodiment 2, it has the same operation as in Embodiment 1.

(Embodiment 3)
The wood dryer used for the wood drying method in Embodiment 3 of this invention is demonstrated referring drawings below. In addition, the same code | symbol is attached | subjected to the thing similar to Embodiment 1, and description is abbreviate | omitted.
FIG. 7 is a cross-sectional front view of an essential part showing the state of accommodation of wood in the drying chamber of the wood dryer used in the wood drying method of Embodiment 3.
In FIG. 7, the wood dryer 1B used in the wood drying method in the third embodiment is different from that in the first embodiment in that the inside of the drying chamber 2 is provided on both sides of the drying chamber 2 in addition to the air circulation fan 6. The point provided with a fan 28 disposed in the air passage 15b and the point provided with a temperature / humidity measuring device 29 for measuring the temperature / humidity in the drying chamber 2 are provided.
By operating the electric fan 28, the hot air or the cold air in the drying chamber 2 is reliably agitated, and the wind passes through the air passage 27 between the materials more efficiently, so that the drying of the material can be promoted.

FIG. 7 shows a cross section of the mouth of the wood 25. Since it is preferable that the hot air or the cold air generated during drying is applied from the longitudinal direction of the material, it is desirable to install the electric fan 28 on the wall 2c in the longitudinal direction of the drying chamber 2. The amount of air generated by the electric fan 28, the number and position of the fan 28 can be selected as appropriate, but it is desirable that the fan 28 be disposed so as to be evenly applied to the entire wood 25.
By measuring the temperature and humidity in the drying chamber 2 using the temperature / humidity measuring device 29, the state in the drying chamber 2 can be easily confirmed, so the operating conditions should be adjusted as necessary. Can do.

According to the wood drying method using the wood dryer in the third embodiment, in addition to the same operations as in the first embodiment, the following operations are provided.
(1) Since the wood dryer has a fan for agitating the air in the drying chamber, the air in the drying chamber is agitated to reduce the temperature and humidity unevenness of the entire drying chamber, and the air in the drying chamber is free from spots Since it can be warmed and cooled efficiently, the atmosphere surrounding the wood can be kept even, the moisture transpiration of individual wood can be kept uniform, and there is little variation in quality after drying. Excellent uniformity and efficiency.
(2) Since the wood dryer has a temperature / humidity measuring device for measuring the temperature and humidity in the drying chamber, the state (temperature and humidity) in the drying chamber can be monitored at all times. It can be reliably maintained and has excellent operational stability and reliability.

The present invention reduces the occurrence of defects such as warping, cracking, shrinkage, bending, etc. of the wood after drying, by leaving the drying temperature not high, and leaving the gloss and fragrance of the surface as it is, the value as a product In addition to drying at low temperature, the entire dryer is surrounded by a heat-insulating layer, so the required energy is small and natural energy is also used, saving energy and protecting the environment. It is easy to install by using a wooden structure for the main body of the equipment and the exterior and interior finishes, and there is no need for a steam generator or excessive electrical equipment, so the capital investment is small and the wood is dried as a whole. cost can be suppressed according to the facilities and easy introduction, installation flexibility can be performed to provide a timber drying process using wood dryer excellent in mass productivity, inherent wood Every time, scent, without impairing the gloss, can contribute to the spread of high-quality dry wood at a low cost.

1,1A, 1B Wood dryer 2 Drying chamber 2a Open / close door 2b Ceiling 2c Wall 2d Floor 3 Heat insulation layer 4 Dehumidifier 5 Temperature control device 5a Heat source 5b Cold source 6 Air circulation fan 10 Pillar 11 Lower ceiling 12 Outside air Introduction fan 13 Indoor air discharge fans 15a, 15b Airway 20 Bogie 25 Wood 26 Pier 27 Airway

Claims (3)

A drying room in which the ceiling part, the wall part, and the floor part are formed in an outer wall and an inner wall in a double layer and have a heat insulating layer between the outer wall and the inner wall, and a temperature for heating and cooling the wood housed in the drying room A wood drying method using a wood dryer comprising: an adjustment device; an outside air introduction fan for introducing outside air into the drying chamber; and an indoor air discharge fan for discharging the air in the drying chamber to the outside of the drying chamber. There ,
And repeating alternately cooling and heating of wood by the regulating device, the temperature of the drying chamber at the time of heating the timber by the temperature adjustment device is a 35 ° C. from 60 ° C., the timber by said temperature adjusting device A method for drying wood , wherein the temperature in the drying chamber when cooling is from 10 ° C to 0 ° C. The drying air in the drying chamber by the indoor air discharge fan with introducing the drying temperature equal to or higher than the warm ambient air of the room to the drying chamber by the air introduction fan during heating start or heating by the temperature adjustment device The outside air is exhausted to the outside of the chamber, and cold air having a temperature equal to or lower than the temperature in the drying chamber is introduced into the drying chamber by the outside air introduction fan at the start of cooling by the temperature adjusting device or in the middle of cooling. 2. The wood drying method according to claim 1, wherein air in the drying chamber is discharged to the outside of the drying chamber. (A) Heating by the temperature adjusting device, (b) Introducing warm outside air equal to or higher than the temperature in the drying chamber into the drying chamber by the outside air introduction fan at the start or during heating by the temperature adjusting device and Introducing outside air to discharge the air in the drying chamber out of the drying chamber by an indoor air discharge fan, (c) cooling by the temperature adjusting device, (d) introducing the outside air at the start or during cooling by the temperature adjusting device. One cycle of four steps of intake of outside air, in which cool outside air equal to or lower than the temperature in the drying chamber is introduced into the drying chamber by a fan and air in the drying chamber is discharged out of the drying chamber by the indoor air discharge fan The wood drying method according to claim 2 , wherein the cycle is repeated until the wood has a target moisture content .

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