JP2011152749A - Apparatus and method for drying wood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus which shortens heat dissipation hours in drying wood. <P>SOLUTION: A drying space 111 to dry wood 100 is formed inside an inner wall part 11. A heat insulating layer 13 is arranged between the inner wall part 11 and an outer wall part 12. A vacuum suction part 2 depressurizes the inside of the heat insulating layer 13 by suctioning air inside the heat insulating layer 13. A heating part 14 dries the wood 100 by heating the drying space 111. After the drying finishes, a water supply part 3 supplies water inside the depressurized heat insulating layer 13. A drainage part 4 discharges water from the inside of the water-supplied heat insulating layer 13. Since a heat dissipation process in drying wood can finish at short times, it becomes possible to shorten the time required for drying wood. If keep-warm hours in the wood drying is lengthened to the time when the heat dissipation hours can be shortened, it is possible to suppress occurrences of cracks in the wood low. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus and method for drying wood.

  Conventionally, techniques for drying wood by heating using a heater have been proposed (see Patent Documents 1 to 5 below).

  Wood drying in these techniques consists of three steps: temperature increase, heat retention, and heat dissipation. First, after wood is carried into the drying chamber, the inside of the cabinet is heated by a heating means such as a heater or heated steam. After the temperature is raised to a predetermined temperature (for example, about 80 ° C. to 120 ° C.), the interior is kept warm within a predetermined temperature range. Also, the air in the cabinet is exhausted by an exhaust fan or a pump. This makes it possible to dry the wood. After keeping the temperature for a predetermined time, heat is released and the wood is removed. A necessary amount of wood can be dried by sequentially performing this operation in a batch manner.

JP 2009-85542 A JP 2006-44135 A JP-A-2005-47100 JP 2004-276438 A JP-A-8-61848

  By the way, if wood has a long waiting time from lumbering to drying, it may crack naturally. If the time required for drying the wood can be shortened, this waiting time can be shortened.

  Moreover, if the drying time of wood can be shortened, the production efficiency of wood can be improved. This is particularly important for small businesses with small stock yards.

  As a method for shortening the drying time per batch, it is conceivable to shorten the drying time by increasing the heat retention temperature (for example, around 120 °) in the above heat retention step and drying it with a short heat retention time.

  However, with such a high heat retention temperature, the wood tends to crack during the heat retention step. In the case of wood, even if a crack occurs, it does not directly lead to a decrease in strength. However, a cracked wood may have a lower transaction price due to the impression that consumers receive from its appearance.

  On the other hand, if the heat dissipation time can be shortened, it is considered that the heat retention temperature can be lowered (that is, the heat retention time can be lengthened) by that amount. Alternatively, it is considered that the drying time per batch can be shortened depending on the amount of shortening of the heat radiation time.

  The present invention has been made in view of such a situation. The main object of the present invention is to provide a technique capable of shortening the heat radiation time.

  Means for solving the above-described problems can be described as follows.

(Item 1)
It comprises a drying device body, a vacuum suction unit, a water supply unit, and a drainage unit,
The drying apparatus main body includes an inner wall portion, an outer wall portion, a heat insulating layer, and a heating portion,
The inner wall portion and the outer wall portion are both formed in a substantially cylindrical shape,
A drying space for drying wood is formed inside the inner wall portion,
The inner wall portion is disposed inside the outer wall portion,
The heat insulating layer is disposed between the inner wall portion and the outer wall portion,
The vacuum suction part is for decompressing the inside of the heat insulating layer by sucking the air inside the heat insulating layer,
The water supply section supplies water into the heat-insulated layer that has been decompressed,
The drainage part is for discharging water from the inside of the supplied heat insulation layer,
The wood drying apparatus, wherein the heating unit dries wood by heating the drying space formed in the inner wall.

  In this wood drying apparatus, the space between the drying space and the outside can be insulated by a heat insulating layer whose inside is evacuated. Furthermore, in this apparatus, the heat in the drying space can be rapidly released to the outside by supplying water to the inside of the heat insulating layer after completion of the heat retaining step. That is, it is possible to dissipate heat within a short time. Moreover, when supplying water to the heat insulation layer made into the vacuum, water will be suck | inhaled in a heat insulation layer and a water supply operation | work can be performed rapidly.

(Item 2)
It also has a controller,
The wood drying apparatus according to item 1, wherein the controller performs the following operation:
(1) The operation of depressurizing the inside of the heat insulating layer to form a vacuum by the vacuum suction unit after wood is carried into the dry space;
(2) An operation of keeping the drying space warm by the heating unit until a predetermined end condition is satisfied;
(3) The operation of supplying water to the inside of the heat insulating layer by the water supply unit after the heat insulation is completed.

  By providing a controller, the wood drying operation can be at least partially automated.

(Item 3)
In addition, it has a relief inlet,
The relief inlet is communicated with the inside of the heat insulating layer,
The wood drying device according to item 1 or 2, wherein the relief inlet is configured to introduce outside air into the heat insulation layer when an air pressure inside the heat insulation layer becomes a predetermined value or less.

  Providing the relief inlet can reduce the possibility that the air pressure inside the heat insulation layer will be a predetermined value or less. Thereby, the excessive deformation | transformation of an inner wall part or an outer wall part can be prevented.

(Item 4)
It also has a door,
The door is configured to close the drying space formed in the inner wall portion so as to be opened and closed,
The wood drying apparatus according to any one of items 1 to 3, wherein the wood to be dried can be carried into the drying space when the door is opened.

(Item 5)
A wood drying method comprising the following steps:
(1) After the wood is carried into the drying space for drying the wood, heat insulation in which the inside is evacuated is performed around the drying space between the drying space and the outside. Forming a layer;
(2) Thereafter, the step of keeping the drying space warm until a predetermined termination condition is satisfied;
(3) A step of supplying water to the inside of the heat insulating layer whose inside is evacuated after the heat insulation is completed.

  By supplying water to the inside of the heat insulation layer whose inside is evacuated, water can be quickly fed into the heat insulation layer, and the heat radiation time can be shortened.

(Item 6)
The wood drying method according to item 5, further comprising the following steps:
(4) After the step (3), discharging the water supplied to the heat insulating layer;
(5) Then, carrying in another wood into the inside of the drying space;
(6) After that, the inside of the heat insulation layer is evacuated by discharging the air in the heat insulation layer.

  According to the present invention, it is possible to quickly dissipate heat after keeping wood warm by feeding water into the heat insulating layer. That is, in the present invention, the heat radiation time can be shortened. As a result, it is possible to lower the temperature for keeping the wood or shorten the drying time of the wood.

It is explanatory drawing which shows the outline of the wood drying apparatus which concerns on one Embodiment of this invention. It is a schematic cross-sectional view of the drying apparatus main body in the wood drying apparatus of FIG. It is a flowchart for demonstrating the wood drying method using the wood drying apparatus of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the wood drying apparatus of this embodiment includes a drying apparatus body 1, a vacuum suction unit 2, a water supply unit 3, a drainage unit 4, a steam generation unit 5, a door 6, and a controller 7. And.

(Drying device body)
The drying apparatus main body (hereinafter sometimes simply referred to as “main body”) 1 includes an inner wall portion 11, an outer wall portion 12, a heat insulating layer 13, and a heating portion 14.

  Both the inner wall portion 11 and the outer wall portion 12 are formed in a substantially cylindrical shape (see FIGS. 1 and 2). In the present embodiment, the inner wall portion 11 and the outer wall portion 12 are both cylindrical, but may be a rectangular tube shape, in other words, any shape that can form a necessary space inside is acceptable. .

  A drying space 111 for drying the wood 100 is formed inside the inner wall portion 11 (see FIG. 2). In the drying space 111, an appropriate support member for stacking wood is arranged. The inner wall portion 11 is disposed inside the outer wall portion 12. The inner wall portion 11 is formed with an intake port 112 for receiving the steam from the steam generating unit 5 and an exhaust port 113 for discharging the air inside the drying space 111. An air exhaust device, for example, an exhaust fan (not shown) is connected to the exhaust port 113. Further, a thermometer (not shown) is disposed inside the drying space 111 so that the temperature in the drying space 111 can be sent to the controller 7.

  An exhaust port 121 for connecting a pipe from the vacuum suction unit 2 and a relief intake port 122 are attached to the outer wall portion 12. The exhaust port 121 and the relief intake port 122 communicate with the inside of the heat insulating layer 13. The relief inlet 122 is configured to introduce outside air into the heat insulation layer when the air pressure inside the heat insulation layer 13 becomes a predetermined value or less.

  The heat insulating layer 13 is disposed between the inner wall portion 11 and the outer wall portion 12. When the door 6 is closed, the heat insulating layer 13 becomes a sealed space in which air does not substantially enter.

  The heating part 14 dries the wood 100 by heating the drying space 111 formed in the inner wall part 11 (see FIG. 1). As the heating unit 14, an appropriate heater disposed in the drying space 111 can be used. Alternatively, the heating unit 14 may be configured to send an appropriate drying medium such as high-temperature air toward the wood 100 from a heating device disposed outside the drying space 111.

(Vacuum suction part)
The vacuum suction part 2 decompresses the inside of the heat insulating layer 13 by sucking the air inside the heat insulating layer 13. In this embodiment, the vacuum suction part 2 is constituted by a vacuum pump connected to the exhaust port 121 of the outer wall part 12 via a pipe.

(Water supply department)
The water supply part 3 supplies water into the pressure-reduced heat insulating layer 13. In this embodiment, the water supply unit 3 includes a water storage unit 31 and a water supply pump (not shown). For example, the water storage unit 31 can store rainwater, and can supply rainwater to the inside of the heat insulating layer 13 by a water supply pump. However, the water supply unit 3 may be configured to supply tap water or well water to the heat insulating layer 13. The water in the present embodiment may be a fluid medium that has a large heat capacity and is easy to handle, such as water, that is, a substance equivalent to water.

(Drainage)
The drainage unit 4 discharges water from the inside of the supplied heat insulating layer 13. In this embodiment, the drainage part 4 is comprised by the drainage pump (not shown) which sends water from the heat insulation layer 13 to the water storage part 31. FIG. However, the drainage unit 4 may be drained by its own weight, or may be configured to drain other than the water storage unit 31.

(Steam generation part)
The steam generating unit 5 supplies steam to the drying space 111 of the inner wall part 11 through the air inlet 112 of the drying apparatus main body 1. Specifically, the steam generation part 5 can be comprised with a steam boiler and required piping.

(door)
The door 6 is configured to close the drying space 111 formed in the inner wall portion 11 so that it can be opened and closed. That is, in the drying apparatus main body 1 of the present embodiment, the wood 100 to be dried can be carried into the drying space 111 with the door 6 opened. Specifically, as shown in FIG. 1, the end portions (the right end portion in FIG. 1) of the inner wall portion 11 and the outer wall portion 12 are opened, and the wood 100 can be carried into the drying space 111 through this opening. It is like that. And by closing the door 6, the drying space 111 and the heat insulation layer 13 can be substantially sealed.

(controller)
In this embodiment, the controller 7 is constituted by a combination of a personal computer and a computer program necessary for its operation. In this embodiment, the controller 7 is configured to execute at least the following operations.
(1) After the wood 100 is carried into the dry space 111, the vacuum suction unit 2 depressurizes the inside of the heat insulating layer 13 to create a vacuum;
(2) The operation of keeping the drying space 111 warm by the heating unit 14 until a predetermined end condition is satisfied;
(3) An operation of supplying water into the heat insulating layer 13 by the water supply unit 3 after the heat insulation of the drying space 111 is completed.

  Detailed operation of the controller 7 will be described as a method for drying wood.

(Wood drying method in this embodiment)
Next, a method for drying wood using the above-described wood drying apparatus will be described with further reference to FIG.

(Step SA-1 in FIG. 3)
In the initial state, it is assumed that the door 6 is open as shown in FIG. In this state, the wood 100 is carried into the drying space 111 in the inner wall portion 11 of the drying apparatus main body 1 (see FIG. 2). Next, the door 6 is closed, and the drying space 111 and the heat insulating layer 13 are sealed.

(Step SA-2 in FIG. 3)
Next, the controller 7 sucks the air inside the heat insulating layer 13 by the vacuum suction unit 2 to make the inside of the heat insulating layer 13 a vacuum. Here, the vacuum means a state where the pressure is reduced to a necessary level. Thereby, the heat insulation layer 13 by which the inside was evacuated for heat insulation between the dry space 111 and the exterior can be formed around the dry space 111.

(Step SA-3 in FIG. 3)
Next, the controller 7 performs the temperature raising process as follows.

(Steam introduction)
The controller 7 introduces the steam generated from the steam generating unit 5 into the drying space 111 through the air inlet 112 of the inner wall part 11. Thereby, vapor | steam can be made to contact the surface of the timber 100, and while heating the surface of the timber 100, it can heat. Thus, the rate of occurrence of cracks on the wood surface can be kept low by introducing steam in the temperature raising step.

(Heating by heating unit)
Further, the controller 7 operates the heating unit 14 to heat the drying chamber.

(exhaust)
Furthermore, the controller 7 discharges the air inside the drying space 111 to the outside from the exhaust port 113 by operating an exhaust device (not shown). Here, the exhaust amount from the drying space 111 is preferably set to be larger than the amount of gas (for example, steam) introduced into the drying space. If it does in this way, the dry space 111 can be made a little negative pressure, and the water | moisture content inside the wood 100 can be discharge | released efficiently.

(Stop steam introduction)
The controller 7 monitors the temperature of the drying space 111. When the temperature reaches a predetermined temperature (for example, 100 ° C.), the controller 7 stops the introduction of the steam from the steam generating unit 15 and proceeds to the next heat retaining process.

(Step SA-4 in FIG. 3)
Next, the controller 7 controls the heating unit 14 to maintain the temperature of the drying space 111 at a predetermined temperature. The holding time is preset by the controller 7 and is, for example, about 10 to 20 hours. However, it is possible to dynamically control the heat retention time by monitoring the water content of the wood 100. Even in this heat retaining step, exhaust from the drying space 111 is continued. In this embodiment, the heat retaining step is performed at a predetermined temperature for a predetermined time. That is, the heat retaining process is performed until a predetermined end condition is satisfied. In the present embodiment, the wood 100 can be dried by a heat retaining process.

  In the wood drying apparatus of the present embodiment, the heat-insulating layer 13 whose inside is evacuated can insulate between the drying space 111 and the outside, so that the amount of heat energy released in the heat retaining process can be kept low. As a result, there is an advantage that the energy use efficiency can be increased.

(Step SA-5 in FIG. 3)
After the heat retention process, the controller 7 supplies water into the heat insulating layer 13 whose inside is vacuumed by the water supply unit 3. That is, the water supply unit 3 supplies the water stored in the water storage unit 31 to the inside of the heat insulating layer 13.

  In this embodiment, since water is supplied to the inside of the heat insulating layer 13 after the heat retention step, heat inside the drying space 111 can be rapidly released to the outside. That is, the heat dissipation process after the heat retaining process can be completed in a short time.

  As described above, the heat retention temperature and the heat retention time are in a trade-off relationship, and when the heat retention temperature is lowered, it is necessary to lengthen the heat retention time. If the temperature is increased, the heat retention time can be shortened, but the wood tends to crack. That is, conventionally, there has been a problem that if the time of the heat retaining step is increased in order to avoid cracking of the wood, the time required per batch is extended. On the other hand, in this embodiment, since the heat radiation time can be shortened, the heat retention time can be lengthened accordingly. Thereby, wood drying efficiency (amount of wood that can be dried per unit time) can be improved while preventing cracking of the wood. In addition, if the heat retention time is constant, it is possible to shorten the time per batch in the wood drying by shortening the heat radiation time.

  In the present embodiment, water is supplied to the inside of the heat insulating layer 13 whose inside is evacuated, so that water is sucked into the heat insulating layer 13. As a result, even if the driving force of the water supply pump is weak, there is an advantage that water can be quickly fed into the heat insulating layer 13. Therefore, in this embodiment, it is possible to further shorten the heat dissipation time. In addition, if a low-capacity water supply pump can be used, the cost required for the facility can be reduced. Furthermore, in this embodiment, depending on the conditions, it is considered possible to omit the installation of the water supply pump and perform sufficient water supply only by opening and closing the water supply valve. In this case, the facility cost can be further reduced. It becomes possible.

(Step SA-6 in FIG. 3)
Next, the controller 7 discharges the water staying inside the heat insulating layer 13 to the outside by the drainage part 4. Specifically, drainage is performed by opening a drain valve of the drainage section 4 or driving a drain pump. Since the discharged water is heated to some extent, it is preferable to return to the water storage unit 31 and cool naturally. In this way, water can be reused. Moreover, in normal wood drying, since it is thought that the time per batch is 20 hours or more, it is thought that it can fully cool only by leaving warmed water. Of course, depending on the state of the wood, the drying time may be shorter, and in such a case, it is possible to cope with the problem by switching a plurality of water storage units.

(Step SA-7 in FIG. 3)
Next, after the drainage is completed, the controller 7 notifies the operator that the drainage is completed by an appropriate means such as lamp lighting. Here, it is preferable that the controller 7 performs control such that the lamp is turned on when the temperature inside the drying space 111 is equal to or lower than a predetermined value (for example, outside air temperature + 20 ° C.). In this way, work safety can be improved. However, it is possible to adopt a configuration in which the temperature in the drying space 111 is notified to the worker by another method.

(Step SA-8 in FIG. 3)
Next, the operator opens the door 6 and carries out the dried wood 100 from the inside of the drying space 111. At this point, one batch of wood drying is completed.

  Thereafter, if necessary, the operator returns to Step SA-1 and repeats the above-described process using the controller 7. That is, another wood is carried into the dry space (step SA-1), and then the air in the heat insulating layer 13 is discharged to make a vacuum in the heat insulating layer 13 (step SA-2). Perform the steps.

  In this embodiment, since the controller 7 is provided, the wood drying operation can be at least partially automated. However, the installation of the controller 7 can be omitted, and in this case, the operator sequentially performs the above steps. The range of control that the controller 7 is responsible for can be changed as appropriate, and the above is merely an example.

  Furthermore, in this embodiment, since the relief inlet 122 is provided in the outer wall portion 12, the outside air can be introduced when the air pressure inside the heat insulating layer 13 becomes a predetermined value or less. Thereby, there also exists an advantage that the excessive deformation | transformation of the inner wall part 11 or the outer wall part 12 can be prevented.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Drying device main body 11 Inner wall part 111 Drying space 112 Inner wall part intake port 113 Inner wall part exhaust port 12 Outer wall part 121 Outer wall part exhaust port 122 Relief inlet 13 Heat insulation layer 14 Heating part 2 Vacuum suction part 3 Water supply part 31 Water storage part 4 Drainage part 5 Steam generation part 6 Door 7 Controller 100 Wood

Claims (6)

It comprises a drying device body, a vacuum suction unit, a water supply unit, and a drainage unit,
The drying apparatus main body includes an inner wall portion, an outer wall portion, a heat insulating layer, and a heating portion,
The inner wall portion and the outer wall portion are both formed in a substantially cylindrical shape,
A drying space for drying wood is formed inside the inner wall portion,
The inner wall portion is disposed inside the outer wall portion,
The heat insulating layer is disposed between the inner wall portion and the outer wall portion,
The vacuum suction part is for decompressing the inside of the heat insulating layer by sucking the air inside the heat insulating layer,
The water supply section supplies water into the heat-insulated layer that has been decompressed,
The drainage part is for discharging water from the inside of the supplied heat insulation layer,
The wood drying apparatus, wherein the heating unit dries wood by heating the drying space formed in the inner wall. It also has a controller,
The wood drying apparatus according to claim 1, wherein the controller performs the following operation:
(1) The operation of depressurizing the inside of the heat insulating layer to form a vacuum by the vacuum suction unit after wood is carried into the dry space;
(2) An operation of keeping the drying space warm by the heating unit until a predetermined end condition is satisfied;
(3) The operation of supplying water to the inside of the heat insulating layer by the water supply unit after the heat insulation is completed. In addition, it has a relief inlet,
The relief inlet is communicated with the inside of the heat insulating layer,
The wood drying device according to claim 1, wherein the relief intake port is configured to introduce outside air into the heat insulation layer when an air pressure inside the heat insulation layer becomes a predetermined value or less. . It also has a door,
The door is configured to close the drying space formed in the inner wall portion so as to be opened and closed,
Furthermore, the wood drying apparatus of any one of Claims 1-3 in which the wood which should be dried can be carried in the inside of the said drying space in the state which opened the said door. A wood drying method comprising the following steps:
(1) After the wood is carried into the drying space for drying the wood, heat insulation in which the inside is evacuated is performed around the drying space between the drying space and the outside. Forming a layer;
(2) Thereafter, the step of keeping the drying space warm until a predetermined termination condition is satisfied;
(3) A step of supplying water to the inside of the heat insulating layer after the heat insulation is completed. The wood drying method according to claim 5, further comprising the following steps:
(4) After the step (3), discharging the water supplied to the heat insulating layer;
(5) Then, carrying in another wood into the inside of the drying space;
(6) After that, the inside of the heat insulation layer is evacuated by discharging the air in the heat insulation layer.

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