JP3165817B2 - Heat treatment drying method for wood - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat-treating and drying wood, in particular, piled wood in a heating chamber.

[0002]

2. Description of the Related Art When a board or other wood is dried in a drying furnace or the like, a so-called cross-stacking in which a suitable cross-bar is sandwiched between the woods to be dried is performed. Conventionally, when drying wood piled in this way, it is loaded into a drying furnace, and the air inside the furnace is heated by a heating device or hot air is sent into the drying furnace to dry it. I was

[0003] However, wood is often bent or cracked in the drying process, but this cannot be prevented by conventional methods, and wood that has been distorted before drying is corrected in the drying process. It was impossible to do that. It would be very advantageous if straightening and straight plate material could be obtained by correcting distortion before drying in the drying process, but such a drying method has not been proposed. In the conventional drying method, wood is naturally dried for a certain period after logging, and then dried in a drying furnace. However, this method requires a considerable period of time after logging to obtain a product. In addition, the deformation of the material due to drying is large, so finishing work after drying is inevitable, and it is necessary to allow for considerable allowance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to efficiently dry a pile of timber without bending or cracking. It is an object of the present invention to provide a method for drying heat treatment. Another object of the present invention is to provide a heat treatment drying method that can dry a raw material immediately after logging without deforming it and obtain a material having a desired shape and dimensions within a small allowable error range. It is in. Still another object of the present invention is to immediately process raw wood immediately after logging, so that the period from logging to sawing is short, so that it is very economically efficient, and dry wood having a predetermined moisture content within a short time. To provide a heat treatment drying method capable of obtaining

[0004]

[Means for Solving the Problems]

[0005] The above object can be achieved by sawing raw wood immediately after felling into a desired shape, heat-treating the raw wood in a superheated steam atmosphere at a temperature equal to or higher than the lignin softening temperature, and drying it. Therefore, in the above treatment, it is desirable to apply a straightening load so that the treated wood has a desired shape, or to perform a heat treatment so as to prevent deformation. Semi-dried wood and wood with partially dried surface layer etc. are not preferable as wood to be treated according to the present invention because their lignin softening temperature is high, but the present invention is only for drying raw wood It is not limited.

In one embodiment of the present invention, the cut timber is immediately sawn, piled, and carried into a heating chamber with a weight for correcting load placed thereon. Then
Air is purged by supplying steam, preferably saturated steam, to the heating chamber, and the temperature of the wood in the heating chamber is raised to a temperature equal to or higher than the lignin softening temperature of the wood. The part is taken out and heated by a suitable heating device, for example, a heat exchanger supplied with high-temperature steam, returned to the heating chamber as superheated steam, and heat-treated and dried in a superheated steam atmosphere. is there. The steam generated as the material dries is guided to a condenser provided outside the heating chamber, where it is cooled and condensed, purified by a suitable wastewater treatment device, and discharged.

[0007] More specifically, the above object is as follows:
Or (g), that is, (a) a loading step of bringing the piled wood into the heating chamber and closing the heating chamber. (b) An air purge step of introducing steam into the heating chamber and discharging the air inside the room to the outside. (c) A step started during or after the execution of the air purging step, in which a part of the steam in the room is taken out, heated and returned to the room as superheated steam, and the temperature of the wood in the heating room is adjusted to the lignin of the wood. Heating step to raise the temperature above the softening temperature. (d) a step performed subsequent to the temperature raising step, in which a part of the steam in the heating chamber is taken out, heated and refluxed as superheated steam into the heating chamber, and the temperature of the wood in the room is kept above the lignin softening temperature for a certain period of time. A heat treatment step of maintaining the temperature at a constant value. (e) a step performed after the heat treatment step, in which a part of the steam in the heating chamber is taken out, excess steam is discharged out of the heating chamber, the remainder is heated, and the steam is returned to the room as superheated steam, and A drying step of evaporating moisture in the wood while maintaining the wood temperature at a predetermined drying temperature higher than the lignin softening temperature. (f) A cooling step to stop the drying step and reduce the wood temperature. (g) Opening the heating chamber and taking out the dried wood. This is achieved by a method of heat-treating and drying the piled wood in a heating chamber, comprising the steps of:

[0008] According to the above method, in the heat treatment step of filling the heating chamber with steam and maintaining the temperature of the room at a temperature higher than the lignin softening temperature of the treated wood,
Lignin between the cellulose structures of the wood is sufficiently softened, deformation such as warpage is corrected by the pressure applied from the pile, and drying is performed in a subsequent drying step in a state where it is restrained so as not to be deformed. Drying can be performed efficiently without producing the problem. According to the method of the present invention, a material having a desired shape can be obtained with a small tolerance,
This is extremely advantageous because a small margin is required in a subsequent finishing step.

Therefore, when the present invention is carried out, the correction in the heat treatment step should be performed quickly and reliably.
Before or after loading the piled wood into the heating chamber, it is recommended that the processing be performed under a corrective load so that the wood has a desired shape. If the wood is a board, it is recommended that the pile be carried out on a rigid pallet using a bar of aluminum square tubes so that the correction load is applied perpendicular to the main plane of the board.

[0010] In this case, it is desirable that the straightening load is applied by a weight having a weight of 600 kg or more and 1200 kg or less per unit load area, which is mounted on the top of the piled timber. Also, if necessary
The pallets on which the timbers are piled may be stacked in two stages, and a weight may be mounted thereon.

When the wood to be treated is raw wood, the room temperature is raised to a heat treatment temperature selected from the range of 75 ° C. to 150 ° C. in the temperature raising step. Is 75 ° C to 15 ° C
It is recommended that the heat treatment temperature is selected from the range of 0 ° C.

In order to carry out the method for heat-treating and drying wood according to the present invention as described above, a wood heat-treating and drying apparatus comprising the following components (a) to (j): , (A) a main body portion is formed of a heat insulating wall, which has a door, a transport device for pallets piled with wood, and a heatable chamber that can be sealed, and (b) discharges air in the heating chamber to the atmosphere. (C) a steam supply source, (d) a steam line capable of introducing steam generated by the steam supply source into the heating chamber at any time, (e) a heating device capable of heating gas in the heating chamber, and (f) ) A device for discharging steam in the heating chamber;
(g) a device for measuring and controlling the temperature in the heating chamber, (h) a device for measuring the temperature of at least a portion of the wood, (i) a device for measuring a change in weight of at least a portion of the wood, and (j) A wood heat treatment and drying apparatus including a central control device for controlling the progress of the heat treatment and drying step can be suitably used.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a method for heat-treating and drying wood according to the present invention.
Explanatory diagram showing one embodiment of a heat treatment drying apparatus used for ,
FIG. 2 is a sectional view showing a weight used to apply a straightening load to the piled materials, and FIG. 3 is a time chart showing an example of a processing process in the wood heat treatment drying apparatus shown in FIG.

In the drawing, 1 is a heating chamber, 2 is a heating chamber 1
Exhaust device for exhausting air inside, 3 is a boiler for generating steam, 4 is a steam supply line, 5 is a steam heating device, 6 is a steam discharge device, 7, 7 is a platform, and 8, 8 are heat treated. The plate members 9 and 9 are crossbars used for crossing, and 10 is a weight that applies a straightening load to the plate member 8. Although not shown in the drawing to avoid complicating the drawing, inside the heating chamber 1, as necessary, a temperature detector for measuring the indoor steam temperature and the temperature of the surface of the plate 8, and the weight of the plate 8. A weight detector for measuring the change, a wood moisture analyzer and other various measuring devices are provided, and a temperature detector for supplied and / or discharged steam is provided outside. The heating chamber 1 has a heat insulating wall 11
The furnace chamber is enclosed by a circle, and includes a door 12 that can be opened and closed, and a safety valve 13, and a chain conveyor 14 for transporting the piled materials is provided inside the furnace chamber.

The exhaust device 2 includes an exhaust valve 22 provided in a pipe leading from the inside of the heating chamber 1 to the outside air. Steam supply line 4
Is a conduit for guiding the steam generated by the boiler 3 to the heating chamber 1, and includes a control valve 41 and a stop valve 42 in the conduit. The steam heating device 5 is a device that takes out steam from the heating chamber 1, reheats the steam, and returns the superheated steam into the heating chamber 1. The heat exchanger 51, the pipelines 52 and 53, the rectifier 54, and the steam control for heating Valve 5
5, the trap 56, the circulation fan 57, the intake valve 58 and the like.

The steam discharge device 6 is a device that cools and condenses steam evaporated from the plate material 8 in the heating chamber 1 and sends it to a wastewater treatment device (not shown).
62, a cooler 63, a shower 64, and a conduit 65. The plate member 8 is formed by using a beam 9 made of an aluminum square tube,
The pile 7 is stacked in two stages, and the weight 10 is placed thereon, and is conveyed by a chain conveyor, a part of which is shown on the right side in the drawing, It is carried into the heating chamber 1 by the chain conveyor 14 in the heating chamber 1.

As shown in FIG. 2, the weight 10 comprises a rectangular plate-shaped iron lump 100 and a plurality of hooks 101 provided so as to be movable within a certain range. The hanging hand 101 is provided with a head 101b at the upper part of the middle trunk part 101a and a frustum-shaped leg 101c at the lower part, and the upper surface of the iron lump 100 using a mounting plate 102 and bolts 103. Attached to. A gap 103 is provided between the hanging hand 101 and the mounting plate 102, so that the hanging hand 101 is movably mounted along the upper surface of the iron lump 100 within a certain range. The weight 10 is configured in this manner so that the weight 10 can be reliably gripped by the crane when the weight 10 is loaded and unloaded by an unillustrated automatic crane.

After the material has been carried in, the door 12 of the heating chamber 1 is closed, and the heat treatment and drying process is started.
Is shown in In FIG. 3, curves A and B are curves showing the steam temperature at two different points in the rectifier 54 in the heating chamber 1, curve C is a curve showing the steam temperature in the center of the heating chamber 1, and curve D is a curve. Curves indicating the temperature of the steam discharged from the heating chamber 1 to the outside, curves E, F and G indicate the surface temperature of the plate material 8 being processed, and curve H indicates a two-stage pile on the platform 7. It is a curve which shows the change of the total weight of the board material 8, the bar | burr 9, and the weight 10 which were performed.

First, at time T0, the piled plates 8, 8 are carried into the heating chamber 1, the door 12 of the heating chamber 1 is closed, and the air purge step is started. In this air purge step, the stop valve 42 is opened, and the steam generated by the boiler 3 is reduced in pressure by the control valve 41 and introduced into the heating chamber. At the same time, the exhaust valve 22 is opened, and the air in the heating chamber 1 is released by the steam to the atmosphere. Extruded inside. Next, in this embodiment, at the time T1 when the air purge step is completed, the next temperature raising step is started. Therefore, the exhaust valve 22 is closed, the circulation fan 57 is started, the heating control valve 55 is opened, and the steam heating device 5 is operated. These temperature raising steps may be started before the air purge step is completed, and both steps may be performed simultaneously for a period of time.

At that time, the circulating fan 57 heats the heating chamber 1
Since the steam extracted from the inside and supplied to the heat exchanger 51 through the pipe 52 has a slightly low temperature, the steam is supplied to the boiler 3.
Is heated by high-temperature, high-pressure steam supplied through a heating steam control valve 55, and is uniformly distributed and supplied into the heating chamber 1 by the steam rectifier 54 as superheated steam. As a result, the temperature in the heating chamber 1 is increased to a higher temperature than the lignin softening temperature of the wood to be treated.

Subsequent to the temperature raising step, a heat treatment step is started at time T2. In this step, steam generated in the heating chamber 1 is extracted by the circulation fan 57, heated, and returned to the heating chamber as superheated steam, whereby the temperature of the heating chamber is maintained at a constant temperature equal to or higher than the lignin softening temperature for a certain time. The plate material 8 is held and heat treatment is performed.

In this heat treatment step, the exhaust valve 2
2. The stop valve 42 and the control valve 62 are all closed, and the steam in the heating chamber 1 is kept in a saturated state, so that the steam generated from the plate is small. The time required for this heat treatment step varies depending on the thickness of the sheet, but is usually about one hour. The plate 8 is
During the heat treatment step, the weight of the weight 10 is received at a constant temperature equal to or higher than the lignin softening temperature, so that bending and warping are corrected and a flat plate without distortion is obtained.

At the time T3 when the heat treatment step is completed, the control valve 62 is opened to shift to the drying step, and the heating chamber 1 is opened.
Start discharging the steam generated inside. Excess steam generated in the heating chamber 1 is sucked into the exhaust fan 65 through the control valve 62, sent to the condenser 63, cooled by the cooling water supplied from the shower 64, and returned to the water, and is shown in the drawing. Not sent to wastewater treatment equipment for processing. The temperature of this exhaust is shown in curve D. In the drying step, the steam generated in the heating chamber 1 is extracted by the circulation fan 57 and heated by the heat exchanger 51 and returned to the heating chamber as superheated steam. As a result, the temperature of the plate material 8 is temporarily reduced as shown by the curves E, F and G, but soon starts to increase.

The differences between the curves E, F and G are as follows:
This is due to differences in materials, dimensions, initial moisture content, and the like. These are all data on cedar wood, curve E is data on sapwood with low initial moisture content, and curves F and G are data on core material with high initial moisture content. The weight of the material shown by the curve H can be determined by, for example, pushing up and supporting one of the typical piers 7 through a weight converter such as a strain gauge.
Known Te. Based on the weight of the material shown in the curve H and the temperatures of the materials shown in the curves E, F, and G, and the rate of change thereof, the dryness of the plate material 8 was determined, and the desired dryness was obtained. At time T4, the heating steam control valve 55 is closed, the supply of steam from the boiler 3 is stopped, and the inside of the heating chamber 1 is naturally cooled.

Generally, the time required for this drying step is 5
About 10 to 10 hours, and that of the cooling step is about 2 to 5 hours. As the drying progresses, the lignin softening temperature rises, and in the cooling step, under the pressure of the weight 10, the temperature of the material is cooled to a temperature sufficiently lower than the lignin softening temperature. During the process,
Since a correction load is applied to the plate 8 by the weight 10, a dry plate having extremely high flatness can be obtained. At the time T6 when the temperature of the wood in the heating chamber 1 has sufficiently decreased, the door 12 of the heating chamber 1 is opened, the dried material is taken out, and the crossing is performed.

[0026]

Since the present invention is Ru configured as on ordination, when according to the invention efficiently raw material immediately after felling, dried without causing bending and cracking, desired within a small tolerance range Can be obtained. In the present invention, preferably, the raw wood immediately after logging is immediately processed, so that the period from logging to lumber is shortened, so that extremely high efficiency can be obtained economically. It should be noted that the raw material has a low lignin softening temperature and is suitable for treatment by the method of the present invention.

The construction of the present invention is not limited to the above-described embodiment. For example, the material to be treated is not limited to a plate, but may be a square or a log. The type of material, the method of stacking, the method of loading straightening load, etc., as well as the material loading / unloading device and the waste liquid treatment device, etc., can be freely changed in design. Is to be included.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a wood heat treatment drying apparatus used in a method for drying wood according to the present invention.

FIG. 2 is a cross-sectional view showing one embodiment of a weight used to apply a straightening load to the piled materials.

FIG. 3 is a time chart showing an example of a processing process in the wood heat treatment drying apparatus shown in FIG. 1;

[Explanation of symbols]

 1 ··· Heating chamber 12 ··· Door 13 ··· Safety valve 14 ··· Chain conveyor 2 ··· Exhaust device 22 ··· Exhaust valve 3 ··· Boiler 4 ···・ Steam supply line 41 ・ ・ ・ ・ ・ ・ Control valve 42 ・ ・ ・ ・ Stop valve 5 ・ ・ ・ ・ Steam heating device 51 ・ ・ ・ ・ Heat exchangers 52 and 53 ・ ・ Pipe line 54 ・ ・ ・ ・ Rectifier 55 ・ ・・ ・ Steam control valve for heating 56 ・ ・ ・ ・ Steam trap 57 ・ ・ ・ ・ Circulation fan 58 ・ ・ ・ ・ Intake valve 6 ・ ・ ・ ・ Steam discharge device 61 ・ ・ ・ ・ Exhaust fan 62 ・ ・ ・ ・ Control valve 63 · · · cooler 64 · · · · shower 65 · · · pipeline 7, 7 · · · platform 8, 8, · · · plate 9, 9, · · · 10 · · · weight

Continuation of front page (56) References JP-A-8-5237 (JP, A) JP-A-64-90983 (JP, A) JP-A-6-50662 (JP, A) JP-A-3-8881 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F26B 9/06

Claims (1)

(57) [Claims] 1. A wood to be treated (8) is accommodated in a drying furnace with a straightening load applied thereto, and air in the furnace is replaced with steam, and a part of the steam in the furnace is discharged outside the furnace. Heat treating the wood (8) by evaporating the water in the wood (8) by heating the steam in the furnace and keeping the wood (8) in superheated steam at a temperature higher than its lignin softening temperature. Method.