JPH0711387B2 - Wood drying equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wood drying apparatus for drying wood such as plate materials and timber.

[Prior Art] A conventional wood drying method will be described by taking a wood drying device 1 as shown in FIG. 9 as an example.
And the dried wood (hereinafter referred to as "wood M") is stacked and accommodated in the drying chamber 5 which is closed by each closed wall of the ceiling wall 4, and the heated air heated by the heating device 6 such as a boiler or a heater is heated. The blower 7 feeds it from the upper part of the drying chamber 5 for forced convection, blows the sent warm air onto the wood M to heat it, and
The water is evaporated from the air, and the evaporated water is contained in the warmed air, and the air containing the water is passed through the refrigerator 8 in the lower part of the drying chamber 5, where the warming is performed. By cooling the air, the moisture in the air is condensed, and the condensed moisture is taken out of the drying chamber 5 to dry the wood M.

[Problems to be Solved by the Invention] By the way, in the conventional wood drying method and wood drying apparatus, the dried wood M is bent or twisted,
In addition, there is a problem that the surface of the wood M is cracked.

Since it convects warm air in the drying chamber and blows it against the wood M, if a turbulent boundary layer occurs on the wood surface, the thermal conductivity becomes large and the wood surface is locally or entirely spread. This is because it is heated rapidly and vaporizes rapidly from the wood surface. In general, wood has a cellular mechanism for protecting itself from desiccation, which has a valve mechanism called torus between cells, and when water vaporizes rapidly, the torus closes and water moves. It is the one that tries to prevent. Therefore, due to the rapid evaporation of the wood surface, the talls are completely closed, and it becomes difficult for water to come out from inside the wood, and the difference in water content between the wood surface and the inside suddenly changes, causing internal stress in the wood. In addition to the above-mentioned bending and twisting, the surface may be too dry, causing cracking.

In order to prevent this, conventionally, as shown in FIG. 9, timbers M are bound together by a band 9 or the like to prevent the timber M from being bent or twisted, and the flow velocity of heated air. And the temperature of the warm air must be adjusted to monitor the temperature unevenness of the wood M from time to time, so the management required for drying was extremely complicated.

Therefore, an object of the present invention is to prevent the rapid heat transfer to the surface of the wood, to prevent the temperature unevenness of the wood, and to dry the wood.

[Means for Solving the Problems] A technical means of the present invention for solving the above problems is to provide a drying chamber that is sealed by floor walls, side walls, and ceiling walls and that accommodates wood to be dried. In a provided wood drying apparatus, a heating wall configured by the floor wall to be heated to radiate radiant heat into the drying chamber, a heating unit for heating the heating wall, and water vaporized from the wood to be dried. And an air discharger having a discharge fan for discharging the air supplied from the air supply unit together with the moisture contained therein to the outside of the drying chamber. And a blower fan provided in the drying chamber to agitate the air supplied from the air supply unit to generate convection in the drying chamber,
The heating wall is formed by crushed stone concrete or stone material in which crushed stones are appropriately mixed, and the heating portion is provided with a pipe through which a heating fluid flows, and the pipe is embedded in the heating wall in a meandering manner. A control device for intermittently driving the supply fan of the air supply unit and the discharge fan of the air discharge unit based on the temperature and humidity of the drying chamber is provided.

[Operation] According to this means, when the sealed wall is heated, relatively warm radiant heat is radiated from the heated sealed wall, and the wood to be dried in the drying chamber is gradually heated so that the whole wood is heated. Is heated almost uniformly. In the uniformly heated wood, moisture is smoothly transferred from the inside of the wood to the surface of the wood and evaporated from the surface of the wood. The evaporated water is absorbed by the air supplied into the drying chamber. Go. Then, this air containing moisture is discharged to the outside of the room.

[Embodiment] A wood drying apparatus according to an embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a wood drying apparatus according to an embodiment of the present invention. The basic structure of this wood drying device is a drying chamber 10 in which wood to be dried (hereinafter referred to as "wood M") is housed,
The floor wall 20 of the drying chamber 10 as a heating wall, the heating unit 30 for heating the floor wall 20, the air supply unit 40 for supplying air into the drying chamber 10, and the drying chamber 10 are provided. Further, the blower fan 45, an air discharge unit 50 that discharges air to the outside of the drying chamber 10, and a control device 60 for these.

As shown in FIGS. 1 and 2, the drying chamber 10 includes a floor wall 20 having a rectangular plane, a side wall 12 standing on a base wall 11 provided on four sides of the floor wall 20, and a side wall 12. It is formed so as to be hermetically sealed by each hermetically sealed wall including the upper ceiling wall 13. The side wall 12a includes an opening / closing door 14 that opens and closes when the wood M is carried in and out of the drying chamber 10, and also has a door 15 through which an operator enters and exits. As shown in FIG. 3, the side wall 12 covers the outside of the heat insulating material 16 formed of glass fiber or the like with the outer plate 17, and
An inner plate 19 is attached to the inside of the sheet with intermediate materials 18a and 18b such as Styrofoam interposed therebetween. The ceiling wall 13 is formed similarly to the side wall 12.

As shown in FIG. 2 and FIG. 3, the floor wall 20 as a heating wall is surrounded by the base wall 11 and has a moisture barrier film 22 and heat insulation such as styrofoam on the roadbed 21 on which stones are piled up. It is laid via material 23. The floor wall 20 is, for example, appropriately crushed stone of about 20 mm so as to be able to emit radiant heat into the drying chamber 10 by heating, particularly long-wave electromagnetic waves ranging from the infrared region to the far infrared region. It is made of mixed crushed concrete.

As shown in FIGS. 1 to 4, the heating unit 30 includes a pipe 31 through which a heating fluid flows, and a boiler 32 that heats the heating fluid to a predetermined temperature (for example, about 80 ° C. to 90 ° C.). And a pump 33 that circulates the heating fluid in the pipe 31. As shown in FIGS. 3 and 4, the pipe 31 has a relatively shallow depth H position (for example, a position 30 mm from the surface of the floor wall 20) on the floor wall 20 and a predetermined pitch P (for example, 15
(0 mm) meandering and buried. Reference numeral 35 is a reinforcing bar that supports the meandering pipe 31 and is embedded in the floor wall 20 like the pipe 31. In addition, the boiler 32 and the pump 33
Is the side wall 12 outside the drying chamber 10 as the boiler pump unit 36.
It is attached to b. Further, as the heating fluid, for example, water mixed with an antifreezing liquid for freeze prevention is used.

The air supply unit 40 includes a supply pipe 41 and a supply fan 42. The supply pipe 41 penetrates the ceiling wall 13, and its intake port 43 is exposed to the atmosphere, while the supply port 44 side in the drying chamber 10 is located at the center of the drying chamber 10 along the ceiling wall 13. Alligator is growing. The supply fan 42 is installed in the supply pipe 41 outside the drying chamber 10, sucks air (in the embodiment, air) that may contain water vaporized from the heated wood M from the inlet 43 and dries it from the supply port 44. It is to be supplied into the chamber 10. Also supply fan
A relatively small size of 42 is used so as to supply an amount of air that can maintain a constant temperature without significantly lowering the room temperature. Reference numeral 46 is a damper provided on the downstream side of the supply fan 42, which is opened when the supply fan 42 is driven, and is normally closed to seal the inside of the drying chamber 10.

The blower fan 45 is provided in the vicinity of the supply port 44 of the air supply unit 40 and blows the supply air from the supply port 44 into the entire drying chamber 10. As the blower fan 45, a relatively small one is used that causes gentle convection so that the fresh air supplied and the conventional air are gradually mixed and agitated. Reference numeral 47 is a guide plate, and a blower fan 45
It guides the air from every corner to reach every corner.

The air exhaust unit 50 includes an exhaust pipe 51 and an exhaust fan 52. The discharge pipe 51 penetrates below the side wall 12c and extends upward along the side wall 12c in the drying chamber 10, and its suction port 53 is near the ceiling wall 13 and does not face the blower fan 45. The outlet 54 outside the drying chamber 10
Is exposed to the atmosphere. The exhaust fan 52 is interposed in the exhaust pipe 51 outside the drying chamber 10, takes in the air containing the moisture evaporated from the heated wood M from the intake port 53, and exhausts it from the exhaust port 54 to the outside of the drying chamber 10. It is a thing. Also, the exhaust fan 52
As with the supply fan 42, a relatively small one is used so as to discharge the amount of air that can maintain a constant temperature without significantly lowering the room temperature. Reference numeral 48 is a damper provided on the downstream side of the discharge fan 52, which is opened when the discharge fan 52 is driven and is normally closed to seal the inside of the drying chamber 10.

The control device 60 includes the side wall 12b above the boiler pump unit 36.
Is attached to, for example, the supply fan 42, the blower fan 45, and the discharge fan 52 are intermittently synchronized based on a signal from a temperature sensor or a humidity sensor (not shown) in the drying chamber 10 or a timer. To drive it. The drive timing is determined based on the temperature condition and the humidity condition in the drying chamber 10, which are predetermined according to the type of the wood M and the initial wet state thereof. In addition, the control device 60
Is provided with a start / stop switch for the boiler 32 and the pump 33, and, for example, based on a signal from the temperature sensor, so that the room temperature of the drying chamber 10 is maintained at a predetermined temperature, the boiler 32 and the pump. The drive stop control of 33 is performed.

Therefore, according to the wood drying apparatus according to this embodiment, first, the opening / closing door 14 of the side wall 12a is opened, the wood M is carried into the drying chamber 10, and the wood M is assembled on the floor wall 20 in a cross shape, for example. Stack up. After that, the opening / closing door 14 is closed to close the inside of the drying chamber 10.

Next, the control device 60 is turned on. As a result, the boiler 32 and the pump 33 are driven to heat the warming fluid to a predetermined temperature and circulate the warming fluid in the pipe 31.

The circulating heating fluid heats the floor wall 20 through the pipe 31 and the reinforcing bar 35, and as shown in FIG. 5, radiant heat is radiated from the heated floor wall 20 into the drying chamber 10. Being done. Then, the radiant heat directly heats the wood M and also heats the air in the drying chamber 10. In this case, the room temperature of the drying chamber 10 rises to, for example, 50 ° C. to 65 ° C. and is kept at this temperature. In this state, the floor wall 20
Is heated and emits mild radiant heat consisting of electromagnetic waves of relatively long wavelength ranging from the infrared region to the far infrared region in the drying chamber 10, so that the surface of the wood M is locally or entirely. It is gradually heated without being rapidly heated. Therefore, the torus between the cells of the wood M is not closed rapidly, and the water is smoothly moved from the inside of the wood to evaporate from the surface of the wood. Therefore, the difference in water content between the surface of the wood and the inside of the wood does not suddenly differ, so that internal stress does not occur in the wood M and the surface does not become too dry, so that bending or twisting of the wood M occurs. And the occurrence of cracks is also prevented. As a result, it is not necessary to bind the wood M with a band or the like. However, in order to prevent the load from collapsing, it is desirable to bind with a band.

After that, when the required time has elapsed, the control device 60
The supply fan 42, the blower fan 45, and the discharge fan 52 are driven. As a result, as shown in FIG. 6, the atmosphere that may contain water vaporized from the heated wood M is changed to the air supply unit.
The air supplied from the supply port 44 of 40 is sent into the entire drying chamber 10 by the blower fan 45, and the exhaust fan 52 exhausts the air from the air exhaust unit 50. In this case, the water evaporated from the wood M is absorbed by the supplied air, and is discharged to the outside together with the conventional air containing the same water, and is replaced with the fresh air supplied. At this time, the flow rate of the supplied and discharged air is relatively small, and the blower fan 45 also causes convection so that the fresh air and the conventional air are gradually mixed, so that the room temperature is
It is maintained at a constant temperature, although it is slightly lowered. Further, air is convected by the blower fan 45, but this air is gentle convection and functions as a medium mainly carrying moisture rather than a medium for heat transfer. There is no adverse effect.

When the required time has passed, the control device 60 controls the supply fan
42, the blower fan 45, and the exhaust fan 52 are stopped, and the heating of the wood M is continued again in the fresh air.

By repeating such a process, moisture is evaporated from the wood M, and the wood M is dried. It has been confirmed by experiments that the time required for the wood M to be appropriately dried is almost the same as the time required for the conventional forced convection heat transfer.

In the above embodiment, the floor wall 20 as the heating wall is made of crushed stone concrete. However, the floor wall 20 is not limited to this. For example, as shown in FIG. 7, a polyhedral stone material with good radiation efficiency is used. 70 may be laid and may be changed appropriately.

In addition, in the above embodiment, the supply fan 42, the blower fan 45, and the discharge fan 52 are driven in synchronization, but they need not necessarily be driven in synchronization and may be changed as appropriate. Further, the sizes of the supply fan 42, the blower fan 45, and the discharge fan 52 may be set appropriately.

In the air supply unit 40 and the air discharge unit 50, respectively,
A feature of the present invention is that the supply fan 42 and the discharge fan 52 are provided to forcibly supply and discharge, but at the development stage thereof, as shown in FIG. A technology was also studied in which a damper 72 that opens and closes according to the pressure difference between the drying chamber and the outside air is provided at the (air discharge port) to naturally supply and discharge. However, if the air is forcibly supplied and discharged, the moisture can be surely discharged, so that the drying efficiency is extremely good. In FIG. 8, reference numeral 73 is an actuator that can open and close the damper 71 forcibly.

[Effects of the Invention] As described above, according to the wood drying apparatus of the present invention,
Since the wood is heated by using the radiant heat radiated from the closed wall, compared to the conventional heating by forced convection,
The surface of the wood does not heat rapidly and the inside of the wood is heated uniformly, so there is almost no change in the water content difference between the surface of the wood and the inside of the wood, and the movement of water from the inside of the wood is smooth. Once done, evaporation from the wood surface can take place. Therefore, the difference in water content does not change abruptly, the internal stress does not occur in the wood, and the surface does not dry out, so it is possible to prevent the bending and twisting of the wood due to this, and also to prevent cracks. It is possible to prevent the occurrence of As a result, it is not necessary to bind the timber with a band or the like, and the efficiency of the drying operation is improved. Further, unlike the conventional case, the power of the blower for obtaining the air volume for the forced convection heat transfer and the power of the refrigerator are not required, so that the power efficiency and the fuel efficiency are significantly improved. Further, since the temperature unevenness of the wood is reduced, the temperature control is not complicated as in the conventional case, and the workability is improved also in this respect.

Further, according to the wood drying apparatus of the present invention, air is positively introduced by the supply fan and the discharge fan, the evaporated water is made to contain the evaporated water, and this is exhausted, so that the drying chamber is filled with the water. Without doing so, the drying efficiency can be improved.

Further, since the convection of air is generated in the drying chamber by the blower fan, it is possible to smoothly absorb the moisture into the fresh air, and the drying efficiency can be improved accordingly.

Furthermore, since the heating unit directly heats the crushed stone concrete or the stone material, it is possible to radiate a long-wavelength electromagnetic wave from the infrared region to the far infrared region from the crushed stone concrete or the stone material, so that the wood is further improved. It can be heated gradually, compared to the case of simply heating the room,
The influence on wood can be further reduced.

In addition, since the control device intermittently drives the supply fan and the discharge fan based on the temperature and humidity of the drying chamber, fresh air is supplied to take in moisture while keeping the temperature as appropriate as possible, and to contain this moisture. The fresh air can be exhausted in a timely manner so as not to be saturated, and in this respect, there is an effect that the drying efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an entire wood drying apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG. FIG. 4 is a plan view showing the piping condition of the floor wall, FIGS. 5 and 6 are equivalent to FIG. 2 showing the operation of the wood drying apparatus according to the embodiment, and FIG. 7 is another example of the floor wall. Partial cross-sectional view, FIG. 8 is a cross-sectional view showing another example of the air supply unit and air discharge unit, and FIG. 9 is a cross-sectional view showing an example of a conventional wood drying apparatus. K …… Wood dryer M …… Wood (wood to be dried) 10 …… Drying room 12 …… Side wall (sealed wall) 13 …… Ceiling wall (sealed wall) 20 …… Floor wall (sealed wall, heating wall) 30 …… Warming unit 31 …… Pipe 32 …… Boiler 33 …… Pump 40 …… Air supply unit 42 …… Supply fan 45 …… Blower fan 50 …… Air discharge unit 52 …… Discharge fan 60 …… Control device

Claims (1)

[Claims] 1. A wood drying apparatus provided with a drying chamber which is sealed by floor walls, side walls and ceiling walls and in which wood to be dried is housed. A heating wall for radiating heat, a heating unit for heating the heating wall, an air supply unit having a supply fan for supplying air capable of containing moisture evaporated from the wood to be dried into the drying chamber, and air. An air exhaust unit having an exhaust fan that exhausts the air supplied from the supply unit together with the moisture contained therein to the outside of the drying chamber, and the air supplied from the air supply unit provided in the drying chamber to agitate the drying chamber. And a fan for generating convection, the heating wall is formed of crushed stone concrete or stone material in which crushed stone is appropriately mixed, and the heating portion is configured by including a pipe through which a heating fluid flows, and the pipe is It is meandering and buried in the above heating wall, Serial drying chamber timber drying apparatus characterized by comprising a control device for intermittently driving the exhaust fan of the supply fan and the air outlet of the air supply unit based on the temperature and humidity.