RU2383433C1 - Method for processing of wood and device for its realisation - Google Patents

Abstract

FIELD: woodworking industry.

SUBSTANCE: method for wood processing consists in preliminary drying of wood in chamber filled with oil, in which wood is submerged into oil below oil level, at the temperature of 50-110°C for 1-15 hours, and in further heating at the temperature of 190-250°C for 1-3 hours. At the same time in process of drying and heating, oil is heated in chamber by means of heat transfer from heated oil, which is circulated via chamber along heat exchanger pipes.

EFFECT: finished product has high quality, due to exclusion of wood interaction with oxygen at the temperature of heating and elimination of direct oil heating in zone of contact with wood, due to simplification of device design.

4 cl, 2 dwg, 2 ex

Description

A method of processing wood and a device for its implementation

The present invention relates to the woodworking industry and can be used to obtain modified wood and products from it.

Until recently, the chemical treatment of wood was the most common for changing the properties of wood. However, due to the harmfulness of the product obtained since the beginning of 2004, a ban on the use of chemically treated wood has been introduced in the European Union. In this regard, at present, various technologies of heat treatment of wood are being actively developed in the world, which are the only alternative to chemical treatment and, at the same time, lead to a significant improvement in the properties of wood, which opens up new areas of its application.

There are various methods for high temperature wood processing. The main objective of all methods to bring the processing temperature to 190-230 ° C. The main problems arising in the process of high-temperature processing are high final temperature, removal of internal stresses in the process of reaching the final (working) temperature, maintaining the uniformity of temperature in the entire chamber volume. The solution of the above problems in the process of high temperature processing leads to the following:

1. Wood can self-ignite when it reaches a temperature of 120 degrees or more.

2. Abrupt (fast) heating leads to deformation (cracking) of wood due to internal stresses.

3. The heterogeneity of the temperature in the chamber gives a spread in the color scheme of the final product even in one tab.

A known method of processing wood billets, including impregnation of wood billets with a modifying solution, drying by heating in vacuum while pressing, and drying and pressing is carried out in a sealed container until the desired moisture content, characterized in that the heating of wood billets is carried out with metal plates heated to 200 ° C. installed above and below each layer of wood billets, and a stepwise increase in pressing force from 0 to 10 MPa, which is located in a straight line the correlation dependence on the temperature increase of the said metal plates, and a simultaneous stepwise increase in the vacuum depth to 43 kPa, and upon reaching the limit parameters of the plate heating temperature of 200 ° C, the pressing forces of 10 MPa, the vacuum depth of 43 kPa, the latter are kept constant until the end of the drying process (RU No. 225857, B27K 5/04, publ. 2005.07.10).

A device for processing wood billets is known from the same source of information. It contains a sealed container, equipped with a pressure plate with a volumetric drive located in the upper part of the said sealed container, means for supplying a modifying solution, means for creating a vacuum, means for heating, the volumetric drive is made in in the form of a non-rigid sealed volumetric element - a bellows mounted above a movable pressure plate, the latter being made with the possibility of vertical movement tions by said actuator volume

The disadvantage of this method and device is its complexity, low quality of the resulting finished product and the structural complexity of the device in which such a method can be implemented.

This source of information is adopted as a prototype for both of the claimed objects.

The present invention is directed to solving the technical problem of eliminating the interaction of wood with oxygen at heating temperatures and eliminating direct heating of oil in the zone of contact with wood.

The technical result achieved in this case is to increase efficiency by reducing time, safety by eliminating the interaction of wood with oxygen and simplifying by eliminating the structural complexity of the device.

The specified technical result in terms of the method is achieved by the fact that in the method of processing wood, which consists in pre-drying the wood and its subsequent heating, the processing of wood is carried out in a chamber filled with oil, in which the wood is placed in oil below its level, pre-drying the wood in this oil is carried out at a temperature of 50-110 ° C with a time of 1-15 hours, and then in the same oil is heated at a temperature of 190-250 ° C with a time of 1-3 hours, while drying and heating the oil in a wasp chamber estvlyayut transfer heat from the heated oil, the circulation flowing through the heat exchanger chamber through the pipes.

At the same time, oil with a flash point above the temperature of heating the oil in the chamber when heating wood is used as oil.

The specified technical result in part of the device is achieved by the fact that the device for processing wood containing a chamber in the form of a container for accommodating wood with heating means, characterized in that the chamber is made in the form of a bathtub filled with oil, and the means for heating the oil in the bathtub is a heat exchanger , a coil and a heating device for transferring heat to a heat exchanger filled with oil and communicated with a coil located in the oil in the bath, and a pump for circulating oil through the channels of the heat exchanger and the snake Vika. In this case, when using two or more bathtubs, it is equipped with a mixing unit in communication with the heat exchanger and configured to distribute the oil heated in the heat exchanger into separate communication lines with the coils in the baths.

These features are significant and are interconnected with the formation of a stable set of essential features sufficient to obtain the desired technical result.

The present invention is illustrated by a specific example of execution, which, however, is not the only possible, but clearly demonstrates the possibility of achieving the desired technical result.

Figure 1 - averaged time-temperature graph;

figure 2 is a block diagram of a device for implementing the method for two bathtubs.

In the framework of this application, a method of wood processing is considered, which consists in bringing the final temperature of wood processing to 190-250 ° C, according to certain time schedules, with preliminary preparation (heating) of wood. The present method is based on the use of a natural thermochemical reaction at temperatures up to 250 ° C without the addition of any chemicals. Due to the high processing temperatures, hemicelluloses decompose in the wood, which against the background of low equilibrium humidity eliminates the conditions for the emergence and reproduction of fungus and microorganisms.

As a result of molecular changes in the structure of wood, primarily due to the depolymerization of cellulose and an increase in its crystallinity, the wood is stabilized - its chemical resistance and geometric stability increase, that is, heat treatment leads to protection from deformation (including “swelling” and “ drying ”) when changing humidity and ambient temperature.

Heat treatment also gives ordinary wood unusual decorative properties; the wood texture is effectively manifested. Moreover, the shade that the wood acquires as a result of heat treatment is caused not by tinting, but by changes in the wood itself under the influence of high temperatures, and the color of the wood is uniform throughout the cross section. Depending on the specified heat treatment mode, you can achieve different colors of wood (from light beige and golden to dark brown).

The high processing temperature allows you to give wood a number of additional properties:

- Increased resistance to environmental factors;

- The destruction of biologically damaging agents in the material;

- Resistance to decay;

- Low hygroscopicity (the original geometry of the product is preserved);

- Thermal conductivity decreases and does not depend on the humidity of the environment;

- Volumetric weight of heat-treated wood is 2.5 times lower than wood, dried in the traditional way;

- The heat-treated modified wood, depending on technological conditions, has a different color scheme up to the color scheme of tropical wood species;

- The color obtained during heat treatment is contained in the entire volume of the product, which exempts from periodic tinting.

To solve the problems during high-temperature processing according to the claimed method, the air medium is replaced with an oil medium (oil) as a coolant in a wood processing chamber, the main condition for choosing oil is the flash point (the flash point must be higher than the final temperature pumped in the chamber) .

The wood processing method according to the present invention consists in pre-drying the wood and its subsequent heating, wherein the wood is treated in a chamber filled with oil, in which the wood is placed in oil below its level, the wood is pre-dried in this oil at temperatures up to 50-110 ° C, the drying time is up to 1-15 hours, and then in the same oil they are heated at a temperature of up to 190-250 ° C with a heating time of up to 1-3 hours, while drying and heating the oil in the chamber is heated heat from heated oil circulating through the chamber through the pipes of the heat exchanger.

For each wood species produces its own temperature-time schedule (figure 1). This graph is averaged, presented to demonstrate the two-stage process of the method. In reality, for each type of wood, both the drying time, and the heating time and temperature of these stages are selected empirically from the calculation of obtaining the required properties for this type of wood and the quality of the original wood.

The use of an oil medium allows you to:

1. Completely exclude the possibility of wood contact with air both at low temperatures and at temperatures above 120 degrees, which eliminates the possibility of burning and carbonization of wood during processing.

2. Due to the higher heat transfer of the oil and the use of experimentally developed modes with gradual heating, it will reduce the deformation of wood.

3. The use of an oil medium also allows us to solve the problem of temperature uniformity in the total chamber volume.

Example 1

The method of processing wood (using birch, hardwood, natural wood, stale 35-45%), the wood is treated in a chamber filled with oil, and placed in oil below its level, pre-drying the wood, as it is a birch, dense and of natural humidity but stale, carried out at 50 degrees with a time of 7 hours, and having completed the preliminary drying step (removing internal stresses and removing partially free moisture), then the temperature is raised to a final value based on the desired color and region p names (in this case, the color is gray, interior decoration), that is, in the same oil they are heated at a temperature of 190 ° C with a time of 1 hour, while drying and warming the oil in the chamber is heated by transferring heat from the heated oil circulating through the chamber through the pipes of the heat exchanger.

After reaching the set temperature and holding the required time, the processing process is completed.

Example 2

The method of wood processing (using birch, hardwood, natural, birch dense humidity is 8-10%), the wood is treated in a chamber filled with oil, and placed in oil below its level, pre-drying the wood, as it is birch, is dense and natural moisture, but stale, is carried out at 110 degrees with a time of 3 hours, and after performing the preliminary drying step (removing internal stresses and removing partially free moisture), then the temperature is raised to the final value based on the required colors and applications (in this case, the color is dark brown, exterior finish, soil-water contact), that is, in the same oil they are heated at a temperature of 250 ° C over a period of 3 hours, while the oil is heated in the chamber during drying and heating heat transfer from heated oil circulating through the chamber through the pipes of the heat exchanger.

After reaching the set temperature and holding the required time, the processing process is completed.

The proposed method can be implemented by a device containing a chamber in the form of a container for placing wood, made in the form of a bath filled with oil, and means for heating the oil in the bath, which is a heating device for transferring heat to a heat exchanger filled with oil and communicated with a coil located in the oil in the bath, as well as a pump for circulating oil through the channels of the heat exchanger and coil. When using two or more bathtubs, the device can be equipped with a mixing unit in communication with the heat exchanger and configured to distribute the oil heated in the heat exchanger into separate communication lines with the coils in the baths.

The following is an example of a device for two baths. The device consists of an energy boiler 1 (heating device) on woodworking waste, a heat exchanger 2 filled with oil, which is heated from the heat of an energy boiler 1, a mixing unit 3, an expansion tank 4, a first bath 5 (chamber) for wood processing, a second bath 6 (chamber) for wood processing, the control unit 7, the main pumping unit 8, the first circulation pump 9 for the first bath and the second circulation pump 10 for the second bath. Bathtubs are made with mechanisms for loading wood into them and unloading. In each bath there is a coil 11 as a system for transferring heat from the oil flowing through it.

The principle of operation of such a device is as follows. There are three independent and disjoint oil circuits:

- the first circuit is the oil filling the first bath 5;

- second circuit - oil filling the second bath 6;

- the third circuit - the oil heated in the heat exchanger 2, comes in a straight line

the pipeline to the mixing unit 3, and then it is divided into each of the baths 5 and 6, then, passing through the coil 11 inside each of the bathtubs (the temperature of the warmer oil of the third circuit returns to the oil in each of the baths in the bath), it is returned via the return pipe to heat exchanger 2.

The circulation is carried out due to the main pumping unit 8 (heat exchanger - mixing unit), as well as due to the circulation pumps of each bath (mixing unit - the first and second baths).

The speed of heating the oil in the baths and, accordingly, in the third circuit is controlled by automation (control unit 7) according to the prescribed temperature graphs.

The present invention is industrially applicable, implemented and has shown high results while ensuring the safety of wood heating to 250 ° C.

Claims (4)

1. The method of processing wood, which consists in pre-drying the wood and its subsequent heating, characterized in that the wood is treated in a chamber filled with oil, in which the wood is placed in oil below its level, the preliminary drying of wood in this oil is carried out at a temperature of 50- 110 ° C with a time of 1-15 hours, and then in the same oil, heating is carried out at a temperature of 190-250 ° C with a time of 1-3 hours, while drying and heating the oil in the chamber is heated by heat transfer from the heated oil, circulating missing Kai chamber through the tubes of the heat exchanger. 2. The method according to claim 1, characterized in that the oil is used oil with a flash point above the temperature of heating the oil in the chamber when heating wood. 3. A device for processing wood, comprising a chamber in the form of a container for accommodating wood with heating means, characterized in that the chamber is made in the form of a bathtub filled with oil, and the means for heating the oil in the bathtub is a heat exchanger, a coil and a heating device for transferring heat to a heat exchanger filled with oil and communicated with a coil located in the oil in the bath, and a pump for circulating oil through the channels of the heat exchanger and the coil. 4. The device according to claim 1, characterized in that when using two or more bathtubs, it is equipped with a mixing unit in communication with the heat exchanger and configured to distribute the oil heated in the heat exchanger into separate communication lines with the coils in the baths.

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