JPH0455361B2 - - Google Patents

Description

[Detailed description of the invention]

- Industrial Application Field This invention relates to a method and device for removing grease from wood, and in particular, it aims to provide a method and device for effectively removing grease from wood with a low moisture content. It is something. - Background of the technology - Live trees felled from mountain forests contain large amounts of water and fat. Therefore, the wood is dried during sawing and used as various lumber.
Naturally dried wood retains a large amount of oil, so when naturally dried wood is used as a variety of lumber, the oil will leach onto the surface of the lumber, especially under high temperatures in the summer. A problem occurs. In the past, wood imported from foreign countries was imported in the form of logs that were close to raw wood, so it was possible to remove some of the fat when drying the wood, but recently wood has been imported from sawn wood. In most cases, the wood is naturally dried, and the wood is also dried during transportation, so it has a low moisture content and contains a large amount of fat. It is made of wood. -Problems to be Solved by the Invention- However, in the past, there was no method to effectively remove fat from wood with a low moisture content of 30% or less. Leaching of fat into the skin was a particular problem. In view of the above circumstances, the present invention aims to provide a method and apparatus that can effectively remove moisture from wood with a low moisture content. -Means for Solving the Problems- The method of the present invention includes a first step of reducing the pressure in a container containing wood, and injecting water into the reduced pressure container to keep the wood immersed in water. second to hold
A third step of discharging the water in the container, and a fourth step of reducing the pressure in the container again and drying the wood by high-frequency heating while maintaining the reduced pressure state, the wood with a low moisture content is removed. This paper proposes a high-frequency heating and drying device for wood connected to a water supply and drainage system to carry out this method. -Function- That is, this invention removes air in the wood structure with a low moisture content under vacuum, and then immerses the wood in water to sufficiently infiltrate water into the wood structure.
After that, the wood is heated from the inside using high-frequency heating to remove the infiltrated water as well as the fat in the wood. When infiltrating moisture into wood, it is more effective to heat the water that has infiltrated the wood, but even without such heating, the air in the wood structure can be sufficiently removed under vacuum. For example, moisture can be sufficiently penetrated into the wood structure. Wood that has been impregnated with water is dried again using high-frequency heating, but according to high-frequency heating under reduced pressure,
The reduced pressure lowers the boiling point of water and fat, and high-frequency heating makes the wood combustible from the center.
While the vapor pressure of water and fat in the center of the wood becomes relatively high, the surface of the wood remains under reduced pressure, so at low heating temperatures the pressure ratio between the inside and surface of the wood increases, and the water and fat evaporates more quickly from the center of the wood, and even if the wood is thick, the fat contained in the center can be reliably removed by heating at a relatively low temperature. -Example- Figures 1 and 2 show an example of an apparatus for carrying out the method of this invention, in which 1 is a closed container, 2 is a sealed container;
is its lid, 3 is a guide rail provided from the bottom of the container 1 to the outside of the container, 4 is a trolley that runs on the guide rail 3, and 5 is a pipe 6 that is connected to the inside of the container 1 via an on-off valve 7 and a condenser 8. connected vacuum pump, 9
10 is a hydraulic cylinder, 10 is a pressing frame attached to the rod of the hydraulic cylinder 9, 11 is a hydraulic pump that supplies pressure oil to the hydraulic cylinder 9, 12 is a switching valve, 13 is a pipe 14 via an on-off valve 15 and a pump 16. a water tank connected in container 1 by
17 is a heating boiler, 18 is a steam pipe installed at the bottom of the container 1 via an on-off valve 19, 20 is an electrode plate attached to the lower surface of the press frame 10, and 21 is an electrode attached to the upper surface of the truck 4. The board 22 is an electrode plate installed between the timbers 23a and 23b to be degreased, and the reference numeral 24 is a high frequency oscillator connected to the electrode plates 20, 21, 22. The water tank 13 is installed at a higher position than the closed container 1, and the connecting pipe 14 communicates with the bottom of the closed container 1. Therefore, by opening the on-off valve 15, the water in the water tank 13 can flow into the closed container 1, and by opening the on-off valve 15 and operating the pump 16, the water can be returned to the water tank 13 in the closed container 1. can. Next, a method for removing fat from wood with a low moisture content using the above-mentioned apparatus will be explained with reference to FIG. First, the pieces of wood 23a and 23b are placed on the cart 4 pulled out from the container 1, and the electrode plate 22 is placed in the center.
Sandwich them and stack them. Then, the cart 4 is loaded into the closed container 1 and fixed to the rail 3, and the lid 2 is closed to seal the container 1. Next, the on-off valve 7 is opened and the vacuum pump 5 is operated to reduce the pressure inside the container 1 to a vacuum state of 30 to 35 Torr and maintain it for 2 hours. Next, the on-off valve 7 is closed to stop the vacuum pump 5, the on-off valve 15 is opened, room temperature water is supplied from the water tank 13 to the container 1, and the container 1 is filled with water, and the valve 15 is closed. Thereafter, the on-off valve 19 is opened to send steam from the boiler 17 into the steam pipe 18 to heat the water in the container 1. In the example shown in Figure 3, the water in container 1 is
It takes two hours to heat up to 80 degrees, and it stays at 80 degrees for about 15 hours. After steaming the wood 23a, 23b in the container 1 in this way,
The on-off valve 15 is opened and the pump 16 returns the hot water in the container 1 to the water tank 13. After water has sufficiently penetrated into the structure of the wood 23a, 23b in this way, known high frequency vacuum drying is performed. That is, the inside of the container 1 is maintained in a vacuum state again by the vacuum pump 5, the high frequency oscillator 24 is activated, and the wood 23 is heated by the electrodes 20, 21, 22.
A high frequency voltage is applied to the timbers 23a and 23b by dielectric heating by applying a high frequency voltage to the timbers 23a and 23b, and the timbers 23a and 23b are kept heated to about 30 degrees and dried. Table 1 shows changes in moisture content when Douglas fir was used as the woods 23a and 23b and was subjected to high-frequency vacuum drying for 48 hours after the steaming treatment shown in FIG. The table shows that the moisture content of the wood increases significantly during steaming, and the moisture content decreases again during the drying process. Almost no fat leaches from the wood treated in this way after drying.

[Table] The above example is a case where wood was immersed in heated water at 80 degrees, but heating is not necessarily required when water penetrates into the wood structure. Table 2 shows the changes in moisture content when wood is immersed in water at room temperature and when it is immersed in water at a temperature of 40 degrees. The moisture content of the wood could be sufficiently increased, and the fat in the wood could be removed by high-frequency vacuum drying of the wood with the increased moisture content.

[Table] - Effects of the Invention - As explained above, according to the method of the present invention, it is possible to effectively remove fat from wood with a low moisture content, leaving the fat inside the wood. It does not become a product and retains its aesthetic appearance for a long time without causing fat to seep onto the surface of the product in the summer and reduce the quality of the product. Therefore, even if the lumber is natural-dried when imported, it can be used as lumber in the same way as lumber obtained by drying raw wood using high-frequency vacuum drying to remove moisture and fat. Furthermore, since the method of this invention does not use chemicals, there are no problems such as contamination or discoloration of the wood, and since it can be processed at low temperatures, the wood is safe with little deformation, and the processing cost is low. It has the advantage of being highly economically effective.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, in which Fig. 1 is a side view of the device showing only the closed container in cross section, and Fig. 2 is a side view of the device showing only the closed container in cross section.
The figure is a front view of the apparatus with the lid open, and FIG. 3 is a time chart showing the temperature and pressure inside the closed container in relation to time in the main steps of the method of this invention. In the figure, 1: airtight container, 2: lid, 4: trolley,
5: Vacuum pump, 10: Pressing frame, 13: Water tank, 16: Water pump, 17: Heating boiler, 1
8: Steam tube, 20, 21, 22: Electrode, 23
a, 23b: wood, 24: high frequency oscillator.

Claims (1)

[Scope of Claims] 1. A first step of reducing the pressure inside the container containing the wood, a second step of injecting water into the reduced pressure container and holding the wood immersed in water, and reducing the pressure inside the container. A method for removing fat from wood, which comprises a third step of draining the water, and a fourth step of reducing the pressure in the container again and drying the wood by high-frequency heating while maintaining the reduced pressure state. 2. A closed container containing wood, two electrode plates placed between the wood contained in the container, a high frequency oscillation device connected to the electrode plates, a water supply and drainage device connected to the container, and A device for removing grease from wood, comprising a vacuum pump.