EP2182313A1

EP2182313A1 - Wood processing device

Info

Publication number: EP2182313A1
Application number: EP07866913A
Authority: EP
Inventors: Yuriy Vasilevich Bodrov; Kirill Yurevich Bodrov; Valentina Alekseevna Bodrova
Original assignee: Obschestvo S Ogranichennoy Otvetstvennostiyu "Bikos - TerMoDerevo"
Current assignee: Obschestvo S Ogranichennoy Otvetstvennostiyu "Bikos - TerMoDerevo"
Priority date: 2007-07-20
Filing date: 2007-07-20
Publication date: 2010-05-05
Also published as: EA201000230A1; WO2009014466A1

Abstract

The invention relates to the wood-processing industry and can be used for wet-heat wood processing. The inventive wood processing device comprises a chamber which is provided with an area for placing a pile of wood, heating elements and a heat carrier circulator arranged in the chamber. The chamber is divided into two cavities by means of at least one partition in such a way that the heat carrier is enabled to flow from one cavity to the other through the area for placing a pile of wood, the input of the heat carrier circulator being hydraulically connected to one of the cavities and the output thereof being connected to the other cavity. At least one of the above-mentioned cavities gradually tapers along the longitudinal axis of the chamber in the direction of the heat carrier flow passing through the cavity which is connected to the output of the heat carrier circulator. Said invention makes it possible to more uniformly process wood.

Description

Field of the Invention

This invention relates to the wood-working industry and may be used in heat-moisture processing of lumber, lumber-based materials as well as a wide variety of wooden articles, namely, boards, bars, parquetry, blanks and finished articles of different shapes, and is especially efficient for drying and toning in treating both hard wood, such as oak, beech, ash, and wood of little value, such as aspen, pine, etc.

Background Art

A device for drying wood is known, which comprises a drying chamber intended for arranging a pile of blanks, a supply air duct, an exhaust air duct, air heaters, a fan and a humidifying device (see, RU 2023963 F26B 3/04, 1994 ). The said device is designed for drying hard wood by the heat carrier (wet steam) having a maximum temperature not more than 85 °C. Therefore, wood cannot be heated above a temperature of its interaction with air oxygen at which wood inflammation can occur.
Also, a device for drying wood is known, which comprises a chamber where nozzles for supplying hot air to a wood pile are installed (see, SU 94719, F27K 5/04, 1960 ). The chamber in the known device for changing the steam condensation velocity has one of its walls made of a heat-conductive material and is covered on its outer side with flap ceramic pads. In the result, the possibility of adjusting the drying rate is provided. However, a disadvantage of the known device is non-uniform heating of a wood pile in the longitudinal direction, which is conditioned by a non-uniform flow rate of hot air along its length due to an increasing pressure reduction in nozzles as the distance from the fan increases.
A wood-processing device is known, which comprises a chamber having an area intended for placing a wood pile, heating elements and heat carrier circulator arranged in the chamber and having its inlet and outlet means (see, RU 2182293, F26B 9/06, 2002 ). The said device is designed so as the area intended for placing a wood pile accommodates a container provided with racks for placing blanks to be processed, or the container may be provided with crossers arranged between wood layers forming the pile. Holes are made in the opposite walls of the container, e.g., in the floor and in the ceiling, which surface area depends on that of the inlet and outlet openings of the circulator of a medium filling the chamber. This ensures a uniform flow rate of a medium filling the chamber through a wood pile along its length. However, on the other side, the presence of the walls does not enable to fully equalize the flow rate of a medium filling the chamber during processing a wood pile as well as increases the resistance of a medium filling the chamber during its circulation within the chamber.
The closest to the claimed invention in respect of the technical essence and the achieved effect is the wood-processing device comprising a chamber having an area for placing a wood pile, heating elements and a heat carrier circulator arranged in the chamber that is separated by at least one partition into two cavities, wherein a heat carrier may flow from one cavity to the other cavity via the area designed for placing a wood pile, the inlet of the heat carrier circulator being hydraulically connected to one cavity and its outlet being connected to the other cavity (see, RU 2235636, B27K 5/00, 10.09.2004 ). The known device enables to process wood with high efficiency and quality, in particular it provides the possibility of processing wood blanks having a width greater than 200 mm, the range of tree species that may be heat-treated is expanded, an average residual moisture of processed wood is reduced, equilibrium moisture content is reduced, uniformity of the wood structure is improved, uniformity of its density is improved and energy costs for wood processing are lowered.
However, when a heat carrier passes through the area designed for placing a wood pile, its flow rate in this area is not constant in the direction orthogonal to the longitudinal axis of the chamber. It results in differences in processed wood being in different places of the pile along its longitudinal axis. This is due to the fact that the phenomenon of locking the heat carrier flow occurs in the volume of the wood pile and the valve effect is observed. This causes a growth in the hydraulic resistance in the volume of the wood pile. Furthermore, a still area is formed in the volume of the wood pile, which limits the intensity of heat exchange in the wood pile.

Summary of the Invention

The objective of this invention is to create and produce a wood processing device ensuring provision of a wood structure having improved, in particular more uniform, characteristics.
The technical effect that may be obtained in the result of achieving this objective consists in that the possibility of provided for more uniform processing of wood in a wood pile, the costs of pumping a heat carrier (working medium) can be lowered due to a significant reduction of whirling cross-flows of the heat carrier in the chamber cavities, an average residual moisture of processed wood is reduced, equilibrium moisture content is reduced, uniformity of the wood structure is improved, uniformity of its density is improved.
These technical effects can be achieved owing to that the claimed wood processing device comprises a chamber having an area designed for placing a wood pile, heating elements and heat carrier circulator arranged in the chamber which is separated by at least one partition into two cavities, a heat carrier being capable of flowing from one cavity to the other cavity via the area designed for placing a wood pile, wherein the inlet of the heat carrier circulator is hydraulically connected to one cavity and its outlet is hydraulically connected to the other cavity, at least one cavity located along the longitudinal axis of the chamber is made narrowing in the direction of the heat carrier flow passing through the cavity that is connected to the outlet of the heat carrier circulator.
The distinguishing feature of this invention is that at least one of the said cavities, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity that is connected to the outlet of the heat carrier circulator. As a result, the heat carrier flow is optimally distributed while passing through a wood pile.
Preferably, wood in the chamber is placed in the form of a pile, and wood layers in the pile are arranged with a spacing between each other.
It is appropriate that a value of the spacing between the adjacent layers in a pile is in the range from 5 mm to 20 mm.
Preferably, circulation of a steam-gas medium is created in the chamber and the circulating steam-gas medium is passed through the pile.
It is appropriate that at least one of the cavities, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity connected to the outlet of the heat carrier circulator by making the inner space of the chamber narrowing in the said direction.
It is also appropriate that at least one of the said cavities, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity connected to the outlet of the heat carrier circulator by forming a wood pile expanding in the said direction.
Preferably, narrowing of the cavities located along the longitudinal axis of the chamber in the said direction is in the range from 1.6% to 24.1%.
It has been experimentally identified that, if narrowing is less than 1.6%, the effect of the absence of the locked heat carrier flow cannot be practically observed, and at a narrowing value greater than 24.1% most heat carrier will come to the area intended for a wood pile at the inlet of the heat carrier.
During processing wood a gauge pressure in the chamber may be maintained at a level not greater than 0.2 MPa.
The method according to this invention may be used for processing various structural elements and blanks that are made of wood.
It is appropriate that the device is provided with a water steam source, which outlet is connected to the cavity of the chamber, and a condensate removal system.
Preferably, the chamber is provided with removable heat-insulation mats arranged at least on a portion of the chamber outer surface.
The heat carrier circulator can be installed inside the chamber or outside the chamber.
Preferably, the inlet and the outlet of the heat carrier circulator is hydraulically connected to the respective cavities via a two-position distribution valve capable of alternatively connecting the inlet and the outlet to the cavities of the chamber.
The device may comprise at least one additional heat carrier circulator that may be installed within or outside of the chamber.

Brief Description of the Drawings

Figure 1 schematically shows a general view of the claimed wood processing device; Figure 2 shows a plan view of the device layout; Figure 3 shows an alternative variant of a plan view of the device layout; Figure 4 shows the device layout viewed from the side of the door opening; Figure 5 shows an alternative variant of the device layout viewed from the side of the door opening; Figure 6 shows still another variant of the device layout viewed from the side of the door opening.

Description of the Best Embodiment

The wood processing device 1 comprises the hermetic chamber 2 having at least one door opening closed by the door 3 that seals the chamber 2. Inside the chamber an area is provided that is designed for placing the wood pile 4. Inside the chamber 2 the heating elements 5 are arranged that may be positioned within the chamber 2 in any commonly known way. Any known devices may be used as the heating elements, e.g., thermal heating elements. The device 1 also comprises the heat carrier circulator 6 for circulating the heat carrier in the chamber. The circulator has the inlet 7 and the outlet 8, through which heat carrier intake and supply occur, respectively. The chamber is separated by at least one partition 9 into the two cavities 10, the heat carrier being capable of flowing from one cavity 10 to the other cavity 10 through the area designed for placing a wood pile 4. At least one cavity 10 located along the longitudinal axis of the chamber 2 is made narrowing in the direction of the heat carrier flow passing through the cavity 10 connected to the outlet of the circulator 6 for circulating the heat carrier. The inlet 8 of the heat carrier circulator 6 is hydraulically connected to one cavity 10, and its outlet 8 is hydraulically connected to the other cavity 10. It is appropriate that at least one of the said cavities 10, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity 10 connected to the outlet of the heat carrier circulator by making the inner cavity of the chamber 2 narrowing in the said direction. According to another variant it is also possible that at least one of the said cavities 10, which is located along the longitudinal axis of the chamber 2, is made narrowing in the direction of the heat carrier flow passing through the cavity 10 connected to the outlet 8 of the heat carrier circulator, by making the wood pile 4 expanding in the said direction (see Fig. 3).
The device 1 is provided with a water steam source 11, which outlet is connected to the cavity of the chamber 2 via the fittings 12. The device 1 is provided with the condensate removal system 13 for the purpose of removing condensed moisture. The system 13 is operated practically at all the process stages and experiences maximum loads when water steam acts on wood. The chamber 2 may be provided with removable heat-insulation mats 14, installed, at least, on a portion of the outer surface of the chamber 2. The heat carrier circulator 6 is arranged inside the chamber 2 as well as outside the chamber 2. In order to maintain a reverse flow of the heat carrier from one cavity 10 to the other cavity 10, the inlet 7 and the outlet 8 of the heat carrier circulator 6 are hydraulically connected to the respective cavities 10 via the two-position distribution valve 15 made with the possibility of alternatively connecting the inlet 7 and the outlet 8 to the cavities 10 of the chamber 2. The device may comprise at least one additional heat carrier circulator 16. The additional heat carrier circulator 16 may be arranged both inside and outside the chamber 2.
The valve 17 is intended for removal the steam-gas medium out of the chamber 2. It is appropriate that the pile is positioned on a trolley 18 which may move, in particular, along the rails 19.
The device according to this invention works as follows. A wood pile is formed on the trolley 18 or directly in the chamber 2 (see Fig. 5, Fig. 6). The wood layers in the pile are at a distance from 5 mm to 20 mm from one another, for which, e.g., spacers are used. After forming the pile, it is moved into the chamber 2 on the trolley 18 along the rails 19. The door 3 of the chamber 2 is closed. Heat insulating mats 14 are attached to the outer surface of the chamber 2 for the purpose of reducing heat losses to the environment (in principle, the walls of the chamber may be already made heat insulating, in which case mats are not required). The heating elements 5 are switched on, and the chamber 2 is pre-heated by heating the air in the chamber 2 at a rate from 30 to 45 degrees/hour until the temperature reaches 130 - 165 °C. When wood is heated, its moisture starts vaporizing. For more efficient heating of the air in the chamber the heat carrier (steam-gas medium) is circulated by the circulator 6. When the temperature in the chamber reaches 130 - 165 °C, water steam is supplied into the cavity of the chamber 2 from the water steam source 11 for 0.5 - 1.75 hours. The steam-gas medium is removed from the chamber 2 via the valve 17. Then, the steam-gas medium formed in the chamber is heated at a rate from 4 to 8 degrees/hour until its temperature reaches 160 - 200 °C, and the wood pile is again acted upon by the water steam for 0.5 - 1.75 hours. After that, the steam-gas medium is again heated in the chamber at a rate from 4 to 8 degrees/hour until its temperature reaches 160 - 200 °C, and the wood pile is maintained at such a temperature for 2.5 - 6 hours. Then, the wood pile is again acted upon by the water steam for 0.5 - 1.75 hours, after which the steam-gas medium is again heated in the chamber at a rate from 4 to 8 degrees/hour until its temperature reaches 160 - 200 °C. Then, the heating elements 5 are switched off, and the heating of the steam-gas medium is stopped in the chamber. In 1 - 3.5 hours after stopping the heating of the steam-gas medium the wood pile is acted upon by the water steam for 0.5 - 1.75 hours.
The heat carrier passes through the wood layers in the pile 4 at a uniform flow rate along its length, thus ensuring more adequate processing of all the layers in the wood pile 4.
After finishing the thermal processing operations the thermal insulation mats 14 are removed from the outer surface of the chamber 2, if necessary, thus increasing the cooling rate of the wood pile by increasing heat removal from the chamber 2 into the environment. After the wood in the chamber is cooled down below 60 °C, the door 3 is opened, and the pile 4 is removed from the chamber 2 to the outside where the wood is cooled completely.
It is obvious that all the thermal processing processes may be adequately automated by installing corresponding sensors and control equipment. Any known devices may be used as such sensors.
The thermal processing stages are carried out in the chamber with the circulation of the steam-gas medium, for which purpose circulators are used. When using such a circulator, it is possible to reverse the heat carrier flow by the two-position distribution valve 15. The use of at least one additional circulator 16 also enables to process wood in the reverse mode of the heat carrier circulation. For this purpose the inlet of the main circulator 6 is connected to one of the cavities 10, and the inlet of the additional circulator 16 is connected to the other cavity 10. The outlets of the circulators 6 and 16 are connected respectively (see Fig. 6). The studies show that residual moisture of wood at any processing stage is not more than 6.2%.
So, owing to a nice appearance and unique properties of thermally processed wood, it may be used in many applications, including finishing interiors of, e.g., baths and saunas, sheathing outer surfaces of houses, making floors, producing furniture, musical instruments, etc.
The cellular structure of wood is changed after thermal processing, becoming similar to that as if wood was dried for several hundreds of years.
Water steam acts as a protective medium and prevents wood from igniting at elevated temperatures due to displacement of oxygen. Thermal processing causes decomposition of sugars, which absence deprives microorganisms of a nutrient medium, such microorganisms also dying at elevated temperatures.

Industrial Applicability

The claimed device according to this invention may be used on the industrial scale for wet-heat processing of lumber, lumber-based materials as well as a wide variety of wooden articles, namely, boards, bars, parquetry, blanks and finished articles of different shapes. The device according to this invention does not require any special equipment or tools.

Claims

A wood processing device comprising a chamber having an area designed for placing a wood pile, heating elements and a heat carrier circulator positioned in the said chamber which is separated by at least one partition into two cavities, a heat carrier being capable of flowing from one cavity to the other through the said area designed for placing a wood pile, wherein the inlet of the said circulator being hydraulically connected with one cavity and the outlet being hydraulically connected to the other cavity, characterized in that at least, one of the said cavities is made narrowing in the direction of the heat carrier flow along the longitudinal axis of the chamber and is passed through the cavity connected to the outlet of the heat carrier circulator.
A device according to Claim 1, characterized in that at least one of the said cavities, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity connected to the outlet of the heat carrier circulator by making the inner cavity of the chamber narrowing in the said direction.
A device according to Claim 1, characterized in that at least one of the said cavities, which is located along the longitudinal axis of the chamber, is made narrowing in the direction of the heat carrier flow passing through the cavity connected to the outlet of the heat carrier circulator by forming a wood pile expanding in the said direction.
A device according to Claim 1, characterized in that it is provided with a water steam source which outlet is connected to the cavity of the chamber.
A device according to Claim 1, characterized in that it is provided with a condensate removal system.
A device according to Claim 1, characterized in that the chamber is provided with removable thermal-insulation mats arranged at least on a portion of the outer surface of the chamber.
A device according to Claim 1, characterized in that the heat carrier circulator is installed inside the chamber.
A device according to Claim 1, characterized in that the heat carrier circulator is installed outside the chamber.
A device according to Claim 1, characterized in that the inlet and the outlet of the heat carrier circulator are hydraulically connected to the respective cavities via a two-position distribution valve provided with the possibility of alternatively connecting the said inlet and the said outlet to the cavities of the chamber.
A device according to Claim 1, characterized in that it comprises at least one additional heat carrier circulator.
A device according to Claim 10, characterized in that the said additional heat carrier circulator is installed inside the chamber.
A device according to Claim 10 characterized in that the said additional heat carrier circulator is installed outside the chamber.