JPS5930876Y2 - wood drying equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a forced drying device for wood, and particularly to a device for drying wood that rapidly dries the wood surface without causing cracks.

Living wood containing 30-100% moisture has a moisture content of 15-10
It cannot be used unless it is dried to %.

This is because if wood that has not been sufficiently dried is used as it is, the wood will shrink as it dries after use, causing cracks, warping, and peeling at bonded areas.

The easiest way to dry wood is to simply stack the wood in a well-ventilated condition, but drying to a moisture content of around 15% with this method depends on the type of wood, but generally speaking In other words, it takes several years, and in this method, no matter how much drying is done, the moisture content reaches an equilibrium state at 15%, and it is impossible to dry it below this level.

There is a method of drying wood in a relatively short period of time by applying hot air or steam to the wood, but the biggest drawback of this method is that
If you raise the heating temperature in order to dry it quickly, only the surface of the wood will overdry and shrink, causing cracks on the surface, so it was not possible to raise the temperature.

When the temperature of the steam was raised to speed up the drying time, numerous cracks appeared on the surface of the wood, significantly reducing the commercial value of the wood.

The inventor of this invention wondered if it was possible to dry wood quickly without causing cracks, and as a result of closely observing the state in which cracks occur on the surface of wood due to hot air drying, he discovered that when hot air is applied to wood, only the surface quickly dries. It was found that the material shrinks when dried, resulting in cracks on the surface.

The shrinkage rate at this time differs slightly depending on the type of wood, but in general, it is 1% in the direction of tree ring connection for each 1% decrease in moisture content.
A few tenths of a percent, for example, the surface has a moisture content of 10% compared to the center.
When dried, the surface shrank by several percent, causing cracks in the radial direction of the annual rings.

Therefore, with this method, it was necessary to gradually heat the entire wood over time, rather than drying only the surface, which significantly extended the drying time.

As a result of further experiments, the inventor of the present invention found that by soaking the wood in boiling water, heating it, removing it from the boiling water, and force-drying it again using hot air, steam, high frequency waves, etc., the wood could be quickly dried without cracking. He succeeded and filed a patent application for this.

However, the problem with this method is that the wood is completely immersed in boiling water and heated, making it difficult to dry large amounts of large wood. There was a drawback that it could only be used.

This is because drying a large piece of wood requires a large amount of drying liquid, a watertight tank with a large capacity, and a great deal of force required to submerge the piece of wood in boiling water.
This is because the heat source heats a large amount of drying liquid, resulting in large heat loss and insufficient heat capacity.

Therefore, the volume of this system was limited to 3000 liters or less, except for special cases.

At the beginning of drying, water droplets are scattered in the drying room in the form of a spray to saturate the indoor humidity while the temperature is still low, maintaining an even distribution of humidity from the outer surface of the wood to the core. Apparatuses that dry wood under the same conditions as natural drying while reducing the drying temperature are known.

(Utility Model Application Publication No. 34-19188) However, this device does not spray water in a heated state, and a part of the heating furnace that heats the liquid for water spraying is exposed inside the drying chamber, which blows the air in the drying chamber. Since the water is heated directly, the mechanism for controlling the water spraying liquid and the temperature inside the drying chamber is complicated, and since the water spraying liquid is circulated through the piping to heat it, the mechanism for that purpose is also complicated. The drawback was that it could not be dried under such conditions.

Furthermore, a wood drying apparatus is also known in which a flame path is provided at the bottom of the drying chamber and a water tank is provided above the flame path.

(Japanese Patent Publication No. 40-20877) However, this device simply evaporates the water in the water tank, and does not spray the water onto the wood, and also heats the water spraying liquid. Since part of the flame path is exposed inside the drying chamber, the temperature inside the drying chamber becomes too high due to the flame path, which has the disadvantage that the wood cannot be dried in ideal conditions.

The important purpose of this invention is to be able to dry a large amount of large wood with a small amount of drying liquid, eliminate the need to make the entire box for storing the wood watertight, and have a simple structure, low cost, and high thermal efficiency, making it economical. Our goal is to provide a wood drying device that is of particular interest.

Hereinafter, first, a method of drying wood using the drying device shown in FIG. 1 according to an embodiment of the present invention will be explained.As shown in FIG. After that, heated liquid drying liquid is continuously sprayed from the nozzle 3 toward the wood for a predetermined period of time, and then the water spraying is stopped and the wood is further forcedly dried with hot air.

The drying liquid is one that can wash away the resin contained in the wood by sprinkling water on the wood, can soften and soften the wood, and can also be easily dried and removed.
For example, water is most suitable.

In addition, the temperature of the drying liquid is preferably a high temperature in order to speed up the drying time, preferably 50 to 100%.
It is best within the range of ℃.

Also, the time for sprinkling water on wood varies considerably depending on the type of wood, the temperature of the drying liquid, the amount of water sprayed, etc., but according to the inventor's experiments, in the case of agarwood with a high oil content and dense grain,
Approximately 10-20 hours with drying liquid at ~90°C was optimal.

However, the watering time varies greatly depending on the thickness of the wood and other factors.

Therefore, for commonly used wood, the watering time is 3
It will take about 120 hours.

However, even if the drying liquid was sprinkled on the wood for a long period of time, no problems such as cracking or warping of the wood occurred.

When the wood is reheated with hot air after water sprinkling is stopped, the appropriate temperature of the hot air is 70 to 90°C.

The drying device shown in Fig. 1 includes a closable box body 2 with a door that allows wood to be brought in and taken out, and injection holes that are arranged at predetermined intervals on the sides of this box body 2 and that open in the box body. A nozzle 3, a drying liquid reservoir 4 with an upward opening disposed below the wood, that is, at the bottom of the box body, to collect the drying liquid sprayed from the nozzle 3; There is a heat exchanger 5 that is a heat source that directly heats the drying liquid, a pump 6 that sucks the drying liquid from the drying liquid reservoir 4 and supplies it to the nozzle, and a forced dryer that forcibly dries the wood after watering. It is equipped with a blower 7 which is a means.

The nozzle 3 shown in FIG. 1 sprays the drying liquid horizontally toward the wood 1 stacked at predetermined intervals so that the entire surface of the wood can be uniformly sprayed.

In addition, the nozzle blows out the drying liquid at a predetermined solid angle, and
Preferably, each nozzle sprays water at a predetermined solid angle so that it sprays water uniformly over the entire surface of the wood.

The diffusion pattern of the drying liquid is determined so that it is uniformly spread in a rectangular shape, that is, the watering state is determined so that water is sprayed all over the square shape, and the nozzle spacing is determined so that each nozzle sprays water with some overlap. do.

If the nozzle diameter is constant, the higher the pressure of the drying liquid sprayed from the nozzle, the more water is sprayed in the form of small mist, and the lower the pressure, the more water is sprayed in the form of large droplets. Ru.

When the drying liquid is sprayed in the form of large droplets, its temperature decreases more slowly when it comes into contact with the wood surface, and the resin that has come out on the wood surface can be more effectively washed off and removed. Also, if the water is in the form of drops or mist, it can be applied more uniformly to the surface of the wood.

Taking these things into consideration, the preferred pressure of the drying liquid supplied to the nozzle is 0.5 to 3 kg/cm2, and the amount of water sprayed from one nozzle is determined to be 10 to 60 l/min. Strength 1 good.

However, the nozzle of the present invention can be any type that can spray the drying liquid onto the wood surface, for example, although not shown, a type that simply allows the drying liquid to flow down in the form of a thread can also be used.

Further, the direction in which the nozzle sprays water may be in the vertical direction as shown in FIG.

The heat exchanger has a cylindrical shape with a burner 8 connected to one end and a chimney connected to the other end. Fire is blown into the interior by the burner, heating the drying liquid in the drying liquid section 4, and indirectly , box body 2
heats the air inside.

The blower 7 blows air onto a heat exchanger that is a heat source, heats the air, and then blows the air onto the wood to forcibly dry the wood.

The operating condition of the wood drying device shown in Fig. 1 is as follows:
After carrying the wood 1 into the interior and closing the door, drying liquid is supplied to the drying liquid section 4, heated by a heat exchanger, water is sprayed from the nozzle 3 by the pump 6, and this state is maintained for a predetermined period of time. After holding, the drying liquid in the drying liquid section 4 may be discharged, and the blower 7 may be operated to blow hot air onto the wood 1 for forced drying.

In the wood drying device of the present application, the heat exchanger that heats the watering liquid heats the watering liquid while being submerged in the watering liquid, and in this state, the air in the drying chamber directly exchanges heat. Since the heat is not heated in a drying container, but through the drying liquid, there is no abnormal temperature rise in the drying chamber, and it is an extremely effective product that greatly simplifies temperature control in the drying chamber and allows wood to be dried in ideal conditions. Realize.

That is, when the heat exchanger heats the water spraying liquid,
It is not directly exposed to the drying chamber like the array drying device, but is surrounded by the watering liquid, so that the surface temperature is maintained below the boiling point temperature of the watering liquid in any case.

For this reason, it is sufficient to simply control the amount of heat generated by the heat exchanger by adjusting the temperature of the liquid used for water sprinkling. It is absorbed as the heat of vaporization of the liquid, and can prevent the temperature of the water spraying liquid and the drying chamber from rising abnormally.

In addition, the water spraying liquid is heated by a very simple structure in which a heat exchanger is installed in the drying liquid reservoir provided at the bottom of the box, and the air in the drying room is also heated by this. This greatly simplifies the structure of the entire device and achieves the outstanding effect of drying wood in ideal conditions.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of a drying apparatus showing an embodiment of the present invention. 1...wood, 2...box, 3...
...Nozzle, 4...Drying liquid part, 5...
...Heat exchanger, 6...Pump, 7...
Blower, 8...Burner.

Claims (1)

[Scope of utility model registration request] A closable box body capable of storing a required amount of wood; a nozzle having a spray port opened in the box body and spraying a drying liquid toward the surface of the wood housed inside the box body; The inside of the drying liquid with an upper opening provided at the bottom of the box for the sprayed drying liquid to flow in and fall, the heat exchanger disposed in this drying liquid reservoir, and the inside of this heat exchanger. A burner blows a flame into the box to heat the drying liquid or the air inside the box via a heat exchanger, a pump that supplies the drying liquid stored in the drying liquid reservoir to the nozzle, and a forced air blower inside the box. When the drying liquid heated from the nozzle is sprayed onto the wood, the heat exchanger is submerged in the drying liquid and the wood is dried. A wood drying device that is configured to heat a drying liquid, and in this state, the air inside the box is indirectly heated by a heat exchanger via the drying liquid.