JPS58130983A - Method and device for drying wood - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drying method and a drying device for low-temperature dehumidifying drying of wood, and aims to improve the quality of wood through uniform drying, reduce drying costs, and promote finish drying. Conventionally, wood has been mainly dried by hot air drying, but this not only increases the drying cost but also inevitably reduces the quality. On the other hand, in recent years, a method and apparatus for drying wood by low-temperature dehumidification using an air conditioner has been put into practical use, and a typical conventional wood drying apparatus is shown in FIGS. 5 and 6.

That is, the wood 51 is stacked in the drying chamber 50, the air in the drying chamber 50 is circulated by the blower 52, a part of the air in the drying chamber 50 is introduced into the adjustment chamber 5S, and after low-temperature dehumidification by the evaporator 54. , by heating with a condenser 55 and an auxiliary heating heater 56.
After being heated to 3 to 38° C., it is fed to a drying chamber 50 through a ventilation path 57.

This drying method and apparatus has the following drawbacks.

1) Since the air is circulated by forced air blowing by the rock, the rectification of the airflow is disturbed due to collisions between the airflow and the wood.
Air does not circulate evenly through the laminated wood. Moreover, since the depth of the drying chamber is large, the pressure difference in the circulating airflow between the upstream and downstream sides is also large, and the temperature and humidity difference is also large, resulting in condensation on the wood on the downstream side. Difficult to dry evenly.

2) Part of the drying chamber is directly connected to the adjustment chamber, and the flow from the drying chamber to the ventilation path and from the drying chamber to the adjustment chamber becomes uneven, so However, the airflow becomes uneven and uniform drying becomes difficult.

3) The evaporator and condenser that dehumidify and heat the air at a low temperature are attached to a refrigerant circuit equipped with a normal compressor, and part of the evaporator's cooling energy is used to heat the air to the dew point. After cooling, the remaining part is used for dehumidification, so the cold energy used for dehumidification decreases by the amount of cold energy consumed for cooling, resulting in a decrease in dehumidification capacity and thermal efficiency.

4) Since it is necessary to keep the heat load on the evaporator appropriate, as long as a normal refrigerator is used, the air in the drying room cannot be made too high, so there is a limit to the speed of finishing drying in the final stage of drying. Therefore, finishing drying cannot be promoted.

In order to solve the above-mentioned drawbacks, the present invention provides a branching chamber at the front of the drying chamber and a suction chamber at the rear, and a ventilation path above these so that a suction fan can act on almost the entire area of the suction chamber. By using negative suction pressure to circulate the air in the drying chamber to the drying chamber, suction chamber, ventilation path, branch room, and drying chamber, and by making the depth of the drying chamber small in the direction in which the airflow flows, small suction in the suction chamber can be achieved. Negative pressure allows circulating air to flow uniformly within the drying chamber, and at the same time, a portion of the air in the suction chamber is sucked into the air conditioning device, where it is precooled by heat exchange with the cooled and dehumidified air in the precooling section of the heat exchanger. After that, it is cooled and dehumidified in the evaporator of the refrigerant circuit, then prehumidified by heat exchange with uncooled air taken in from the suction chamber in the prehumidification part of the heat exchanger, and then further humidified in the condenser of the refrigerant circuit. The heated air is then sent to the ventilation path, mixed uniformly with the air that has flowed into the ventilation path from the suction chamber, and this mixed air is sent from the distribution room to the drying room, and in the final stage of drying. , the temperature in the drying chamber is raised to 45° C. or higher to promote finish drying.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the wood drying apparatus of the present invention and examples of implementation procedures of the drying method will be described below with reference to the drawings.

The drying shed has a hermetically sealed structure, and a door 1 can be used to open and close the wood carrying capacity 1A in front of the drying shed.

A drying chamber 2 is provided in the center of the drying chamber, a diversion chamber 5 is provided in the front, and a suction chamber 4 is provided in the rear. Ventilation passage 5 is located above the chamber 4.
is widely formed.

The two front faces of the drying chamber 2 are fully communicated with the branching chamber 6, and the rear face 2B and the suction chamber 4 are separated by a porous partition plate 6 having a large number of ventilation holes. By applying uniform resistance to the entire surface with this porous partition plate 6, the drying chamber 2
The ventilation resistance from the to the suction chamber 4 is made uniform over the entire surface.

Furthermore, the space between the drying chamber 2/suction chamber 4 and the ventilation path 5 is partitioned by a non-ventilated partition ceiling plate 7, but in order to circulate the air in the drying chamber 2, the suction chamber 4 and the ventilation path 5 are separated. An intake fan 9 is attached to the circulation vent 8' of the partition ceiling plate between the two.

Further, the upper surface of the branch chamber 5 is completely communicated with the lower surface of the front end of the ventilation passage 5.

The air inside the drying chamber 2 is sucked into the drying chamber 2 by the suction fan 9 mentioned above.
- The suction chamber 4, the ventilation path 5, the diversion chamber 6, and the drying chamber 2 are circulated in this order. The drying chamber 2 is formed into a short passage type drying chamber 2 by setting the depth in the direction in which the circulating airflow flows to be sufficiently smaller than its width in the left and right direction, so that drying can be performed using a small suction negative pressure applied to the suction chamber 4. Drying air quickly flows through all of the wood W stacked in the chamber 2. In this way, the difference in temperature and humidity of the air between the upstream and downstream sides within the drying area is relatively small, and uniform drying is achieved.

A unit-shaped air conditioning device A is installed at the rear of the drying cabinet.
The suction port 12 is connected to the suction chamber 4, and the supply port 15 is connected to the ventilation path 5.

This air conditioning device A is for sucking in a part of the air in the suction chamber 4, dehumidifying it at a low temperature, heating it, and circulating it through the ventilation passage 5. The precooling section 14a1 of the heat exchanger H and the evaporator 1 are installed in the order from the upstream side.
5. The prehumidification section 14b1 of the heat exchanger H is provided with an auxiliary heater 18 consisting of a condenser 16, a suction fan 17, and an electric heater.

The heat exchanger H is, for example, a diaphragm heat exchanger shown in FIG. 3, which has a structure in which corrugated metal plates are alternately oriented vertically and horizontally and sandwiched between flat metal plates, and the air flowing through the pre-cooling section 14ai. The evaporator 15 and the condenser 16 are incorporated into a refrigerant circulation path 20 in which a compressor 19 is interposed between the evaporator 15 and the condenser 16, and the condenser 16 The evaporator 15 serves as a heater, and the evaporator 15 serves as a cooler. 1. Reference numeral 21 is a liquid receiver, 22 is an expansion valve, 25 is an exposure receiver, and a cH cooling tower.

Wood is dried using the above-mentioned wood drying apparatus according to the following procedure.

After storing the wood 24 in a layered manner in the drying chamber 2, the door 1 is placed in a substantially sealed state, and the air in the drying chamber 2 is dried by applying negative suction pressure to almost the entire area of the suction chamber 4 using the suction fan 9. The chamber 2, the suction chamber 4, the ventilation path 5, the branch chamber 6, and the drying chamber 2 are circulated in this order.

At the same time, the air conditioning device A is operated to suck a part of the air in the suction chamber 4 through the suction port 12, and the pre-cooling section 14a
After pre-cooling, the intake air is further cooled and condensed in the evaporator 15 to dehumidify the intake air, and then this dehumidified air is pre-humidified in the pre-humidifying section 14b and then heated in the condenser 16. The auxiliary heater 18 is operated to heat the dehumidified and heated air, and this dehumidified and heated air is sent into the ventilation passage 5 from the supply port 15, and is forcedly fed into the ventilation passage 5 from the suction chamber 4 through the suction fan 9 within the ventilation passage 5. The air is mixed uniformly with the undehumidified air before being transferred to the diversion chamber 6.
flows into.

In the above, when the undehumidified air taken in through the suction port 12 passes through the pre-cooling section 14a, it is pre-cooled by exchanging heat with the low-temperature dehumidified air that has flowed into the pre-humidifying section 16 from the evaporator 15. Ru.

In this way, a part of the cold energy required for low-temperature dehumidification is input into the pre-cooling section 14a, so after flowing into the evaporator 15, the cold energy from the evaporator 15 quickly reaches the dew point and condenses, resulting in efficient dehumidification. Ru.

When this dehumidified air passes through the pre-humidifying section 14b, the pre-cooling section 1
It is prehumidified by heat exchange with the heated undehumidified air flowing 4ak, and the undehumidified air is precooled as described above.

Note that the dehumidified air is further heated in the condenser 16, and then also heated by the auxiliary heater 18 as required.

Here, wood drying must be carried out at a speed that is compatible with the movement of moisture from the inside of the wood to the outside, so at the beginning of wood drying, the air temperature in the drying chamber 2 is gradually rising. Therefore, the heating temperature in the condenser 16 and the auxiliary heater 18 is adjusted to be in the range of about 35 to 40°C,
In the middle of drying, drying is continued while maintaining the temperature above the road.

That is, the humidity of the air in the drying chamber 2 is controlled so that the drying rate corresponds to the type, size, shape, moisture content, etc. of the wood.

In the final drying stage, where the moisture content drops from about 17 to 16 inches, the drying progresses slowly, so the air temperature inside the drying chamber 2 is raised to about 45 degrees Celsius or higher. , to accelerate finish drying and dry until the final moisture content of the wood is about 15 inches.

In addition, as a modification of the above air conditioning device, as shown in FIG. 4, a pump 25 tl-
A pre-cooling section 14a and a pre-humidifying section 14b of the heat exchanger H through which the liquid refrigerant of the interposed refrigerant circulation path 26 flows are provided upstream and downstream of the evaporator 15, respectively.

In this way, heat is exchanged between the undehumidified air and the dehumidified low-temperature air via this heat exchanger H.

Since the present invention is configured as described above, it has the following effects.

b) The front side of the drying chamber and the separation chamber are communicated almost completely, and the rear side of the drying chamber and the suction chamber are communicated almost completely, and negative pressure is sucked by a suction fan interposed between the suction chamber and the ventilation path. Since the airflow acts uniformly over almost the entire area of the chamber, and the depth in the direction in which the airflow flows is made small, the circulating airflow is evenly distributed in the width and height directions of the drying chamber, which not only makes the drying uniform, but also improves drying efficiency. The temperature and humidity differences in the circulating airflow between the upstream and downstream sides of the room also become smaller and more uniform.

Therefore, all the wood stacked in the drying chamber can be uniformly dried under substantially the same conditions without variation.

In the air conditioner, the air sucked from the suction chamber is pre-cooled by heat exchange with the cooled and dehumidified low-temperature air through the heat exchanger, and then cooled and dehumidified by the evaporator in the refrigerant circuit. Of the generated cold energy, less is consumed to cool undehumidified air to the dew point, and more cold energy is used for dehumidification.

As a result, the amount of dehumidification increases, and the dehumidification capacity increases by about 3 to 4 times compared to conventional devices, so the air conditioning device can be made smaller and more efficient.

c) In the final stage of drying, the heating temperature of the condenser and auxiliary heater is increased to bring the air temperature in the drying room to over 45℃, which accelerates final drying and significantly shortens the drying period. You can.

In this case, by pre-cooling in the pre-cooling section,
Since the temperature of the air flowing into the evaporator can be set below the permissible temperature of the evaporator of a normal refrigerator (approximately 35° C.), there is no need to use a special refrigerator.

[Brief explanation of drawings]

1 to 4 show the wood drying apparatus of the present invention, and the first
The figure is a cross-sectional plan view, Figure 2 is a longitudinal side view, Figure 3 is a schematic perspective view of the heat exchanger, Figure 4 is a view corresponding to the section ■ in Figure 2 of a modified example,
Figures 5 and 8g6 are jig I diagrams and diagrams corresponding to Figure 2 of conventional equipment, respectively.
...Drying room, 2 people...2 front, 2B...2 back, 6
...Diversion chamber, 4.. Suction chamber, 5.. Ventilation passage, 9.. Suction fan, 12.. Suction port, 1! I...Feeding port, H...Heat exchanger, 14a...H precooling section, 1ab; tH premixing section, 15...Evaporator, 16...Condenser, 17..., Suction fan, 19 ...Compressor, 24...Wood. Patent applicant Dainichi Engineering Co., Ltd. Iwatani Sangyo Co., Ltd. Figure 3 g6

Claims (1)

[Scope of Claims] 1. In the drying chamber, a branching chamber 6, a drying chamber 2, and a suction chamber 4 are provided in order from the front side, and a ventilation passage 5 is provided above these, and a suction fan 9 is provided in the suction chamber 4. , by applying the suction negative pressure of the suction fan 9 substantially equally to the entire area of the suction chamber 4,
The air in the drying chamber 2 is circulated through the drying chamber 2, the suction chamber 4, the ventilation path 5, the branching chamber 5, and the drying chamber 2, and the air conditioning device A is provided inside or outside the suction chamber 4. A part of the air in the suction chamber 4 is sucked, cooled and dehumidified, and the temperature is adjusted to be heated before being sent to the ventilation passage 5. In the air conditioning device A, the air sucked from the suction chamber 4 is pre-cooled in the heat exchanger H. Part 14a1 Evaporator 15 of the refrigerant sent from the compressor 19, Prehumidification part 14b of the heat exchanger H, and Condenser 1 of the refrigerant sent from the compressor 19
6, and when this air passes through the pre-cooling section 14at, it is pre-cooled to a low temperature by heat exchange with the dehumidified cold air sent from the evaporator 15 to the pre-humidifying section 14b, and then further cooled in the evaporator 15. It is dehumidified while being cooled, and when the cold air after dehumidification passes through the prehumidifying section 14bTh, it is prehumidified by heat exchange with uncooled air passing through the precooling section 14a, and then further heated in the condenser 16, and this dehumidified air is The heated air is supplied to the ventilation passage 5, mixed almost evenly with the air supplied from the suction chamber 4 to the ventilation passage 5, and then sent into the drying chamber 2 via the distribution chamber 5 to dry the wood. At the final stage of drying, the condenser 16 of the air conditioner A and the auxiliary heater 1 are used more than before.
A wood drying method 2 characterized in that the heating temperature in step 8 is further increased to raise the air temperature in the drying chamber 2 to 45° C. or higher to promote finish drying, according to claim 1M1. In the wood drying method described, drying chamber 2
Method 3 Drying: By making the depth in the direction in which the air flows as small as possible, air can quickly flow between the stacked timbers 24 in the drying chamber 2 with a small negative suction pressure exerted on the suction chamber 4. A diversion chamber 6, a drying chamber 2, and a suction chamber 4 are provided in order from the front inside the storage compartment, and a ventilation passage 5 is provided above these. The upper end of the branch chamber 6 is in communication with the ventilation passage 5 almost entirely.
At the front end of the suction chamber 4, the upper end of the suction chamber 4 communicates with the rear end of the ventilation passage 5, and a suction fan 9 is attached between the upper end of the suction chamber 4 and the ventilation passage 5, so as to connect the inside and outside of the suction chamber 4. The suction port 12 of the air conditioning device A provided on either side is connected to the suction chamber 4, and its supply port 15 is connected to the ventilation path 5, and heat is exchanged from the suction port 12 to the air path leading to the supply port 15. Pre-cooling section 14a of vessel H, compressor 1
An evaporator 15 for the refrigerant sent from the pre-cooling section 14b1 of the heat exchanger H, a condenser 16 for the refrigerant sent from the compressor 19, and a suction fan 17 are attached. t- A wood drying device which is configured to be able to exchange heat with the passing air, and is characterized in that the drying chamber 2 is capable of accommodating wood 24 in a layered manner and has a small depth in the front and back direction. Apparatus 4 In the wood drying apparatus described in claim 3, a porous partition plate 6 is provided on substantially the entire rear surface 2B of the drying chamber 2, and the drying chamber 2 and the suction chamber are connected through the porous partition plate 6. connected with 4