EP0652089A1 - Process and apparatus for thermal treatment of wood, particularly of wooden beams for frameworks, against parasites - Google Patents

Abstract

a) Process and apparatus for treating wood, particularly beams of frameworks against parasites. b) Process characterised in that: - the pieces to be treated are enveloped with a heating electrical element, the external surface of which has good heat-insulating (lagging) characteristics, closely covering the piece to be treated, - a temperature profile as a function of time is controlled in order to bring the core (heart) of the piece to be treated up to a given temperature, guaranteeing the destruction of the parasites inside the wood, - the temperature profile is determined as a function of the nature and age of the wood as well as of the cross-section of the piece to be treated, - the, preferably alternating, supply to the various heating elements is controlled using a control station, and at the end of the treatment each heating element is removed. <IMAGE>

Description

The present invention relates to a method and an installation for the thermal treatment of wood, in particular of structural beams against pests.

The protection of wood and in particular of frameworks against pests is an increasingly delicate problem.

Indeed, until recently, it was customary to protect wood, especially relatively thick wood such as beams, by injecting an insecticide, combined with brushing or spraying the exterior surface of the wood .

However, the products formerly used have proven to be very dangerous for human health, so these products have been renounced. There are also products that apparently do not pose a danger to humans. However, their effectiveness is relatively low and their implementation quite complicated.

Indeed, these products are used in the form of mist, so it is necessary to constitute an enclosure closed in an almost hermetic manner at the level of the frame of a house then pump the steam loaded with this product in this enclosure. The facilities for applying such treatment are relatively complicated; a vehicle is needed with the equipment supplying this vapor charged with insecticide as well as ducts to connect the vehicle to the attic, for the supply of gases.

As the treatment is relatively long (several hours), the application of this process represents a significant inconvenience, especially for treatments in urban or suburban areas.

Attempts have also been made to treat the heart of the wood by microwaves. However, here again, the equipment to be used is relatively delicate and heavy, all the more so since the manipulator must be protected against radiation leaks.

The object of the present invention is to create a simple and effective means of heat treatment of wood, in particular of structural beams, joists, etc. by simple means, easy to implement and not creating any disadvantages or particular discomfort for the environment or the inhabitants.

• on enveloppe les pièces à traiter avec un élément électrique chauffant dont la surface extérieure a de bonnes caractéristiques d'isolation thermique, en entourant étroitement la pièce à traiter,
• on commande un profil de température en fonction du temps pour conduire le coeur de la pièce à traiter à une température déterminée, garantissant la destruction des parasites à l'intérieur du bois,
• on détermine le profil de la température en fonction de la nature et de l'âge du bois, de l'hygrométrie ainsi que de la section de la pièce à traiter,
• on commande l'alimentation de préférence alternée des différents éléments chauffants à l'aide d'un poste de commande et à la fin du traitement on enlève chaque élément chauffant.

To this end, the invention relates to a process for treating wood by heat, characterized in that:

• the parts to be treated are wrapped with an electric heating element whose external surface has good thermal insulation characteristics, by closely surrounding the part to be treated,
• a temperature profile is controlled as a function of time to drive the core of the part to be treated to a determined temperature, guaranteeing destruction parasites inside the wood,
• the temperature profile is determined as a function of the nature and age of the wood, of the humidity as well as of the section of the part to be treated,
• the supply of alternately the different heating elements is preferably controlled using a control station and at the end of the treatment each heating element is removed.

The invention also relates to an installation for implementing this method, this installation being characterized in that the different layers are supplied in a nested fashion.

• la figure 1 est un dessin schématique de l'installation selon l'invention et de sa mise en oeuvre sur une forme de toiture.
• la figure 2 montre schématiquement un élément chauffant.
• la figure 3 montre un élément chauffant particulier.

The present invention will be described below in more detail with the aid of the accompanying drawings in which:

• Figure 1 is a schematic drawing of the installation according to the invention and its implementation on a roof form.
• Figure 2 schematically shows a heating element.
• Figure 3 shows a particular heating element.

According to the figures, the invention relates to a method and an installation for heat treatment of wood, in particular of structural timber, against parasites.

The installation consists of heating elements in the form of flexible sheets, one of which (internal face) is heated and the other face (external face) is insulating. These elements, of rectangular, triangular or generally polygonal format, are provided with closure means such as removable fastening strips making it possible to wrap the part to be treated with the element and to close the element on the part. . These attachment means allow to stretch the element's web to apply it tightly against the part to be treated.

In the example shown in Figure 1, the heating elements 1, 2, 3, 4 envelop parts of beams 100, 101, 102 of a structural truss.

The number of elements to be installed depends on the site. The shape of the heating elements will be discussed later.

These elements 1-4 are connected by cables 11, 12, 13, 14 to a power supply unit 15, controlled by a control panel 16. The elements 1-4 are also provided with temperature sensors 21-24, which supply their signals to the control panel 16 via the supply unit 15. The control panel 16 manages the supply of the various heating elements 1-4 according to a determined program and as a function of the temperature measured in the part treated using the sensor associated with each element.

The temperature sensors 21-24 can be integrated into the sheet or constitute separate bodies but nevertheless preferably associated with each heating element (1-4). The cable for transmitting the electrical signals for measuring the temperature is preferably joined to the power supply cable for the heating element to simplify the installation and removal of the cables and the heating elements. In some cases, for large surface or length elements, it may be useful to provide several sensors.

The heating elements (1-4) are connected to the power supply unit 15 by sockets 151-154 allowing the elements to be placed, the elements to be connected on standby, etc.

In addition, to simplify the drawing, the sockets for connectors, sensors have not been shown on unit 15.

To facilitate the management and installation of the heating elements, these and the sockets of the power supply unit 15 are identified by references or codes.

The control panel 16 also allows the sequential supply of the various heating elements to avoid excessive power calls when the installation is started up.

In this way, the different elements are supplied successively or in a nested manner (by a chopped current, distributed between the different elements), at least during the rise in temperature then for the maintenance of this during the cruising speed, for the temperature maintenance.

This also makes it possible to suffice from the electrical supply normally available in the building and which would be insufficient to provide the starting power for all of the elements, all connected at the same time.

The electrical supply is ensured for example from the building by means of a simple cable 17 connected directly to the power supply unit 15.

The control panel 16 includes a microprocessor for managing the electrical distribution according to the different temperature curves and a printer 161 which establishes a report of the treatment operation by recording on a paper support the evolution of the temperature at the level of each element or part treated.

According to the invention, the installation is preferably used in the following manner:

The manipulator starts by placing some elements 1-4 around beams 100-102 to be protected then it connects their electrical supply which is automatically managed by the control panel 16. During this treatment period, it gradually sets up the other elements around other parts to be treated; it plugs them in and their temperature rise takes place while the elements already placed are at their operating temperature; this also makes it possible to fairly fairly distribute the demand for electrical power over the treatment period.

The operations are repeated; at the end of the processing period for the first parts, the manipulator disconnects these elements, removes them to possibly place them on other parts to be treated.

The heating of the wood in the rooms is controlled so that the temperature rises in the heart of the wood and destroys the wood parasites there by simply raising the temperature.

As the treated areas are surrounded in a relatively tight manner with the heating element or elements, the humidity which would risk being released from the wood, remains confined in this heating chamber; during cooling, humidity thus re-enters the wood, which avoids drying out the treated wood.

As the treatment temperature and above all the maximum temperature is controlled according to the nature of the wood and the section of the parts to be treated, it is possible to optimize the treatment both in temperature and in duration.

Figures 2 and 3 show two examples of shapes of heating elements 200, 300.

The heating element 200 is a flexible rectangular sheet having the characteristics already described (internal heating surface and external surface insulating). This element is provided with fasteners 201, 202 on one side and fasteners 203, 204 on the other side for wrapping the part to be treated in two winding directions. These 200-204 fasteners are for example adjustable, claw fasteners or adhesive fasteners.

FIG. 2 also shows two temperature sensors 205, 206, the conductors of which are combined with the power supply cable 207 of the element 200. The cable 207 ends with the power connector 208 and the connector 209 of the sensor conductor .

The heating element 200 can for example be used like elements 1-4 in FIG. 1.

FIG. 3 shows a particular element 300 which can be used to wrap a T-junction of two beams like the 100/102 beams.

For this, it itself has a T-shape with two branches 301, 302 and fasteners 303, 304, 305, 306 as well as temperature sensors 310, 311, 312 connected to the common cable 307. The latter is provided as previously a power connector 308 and a connector 309 for temperature signals. It should be noted that the heating elements can also be used to treat partially inaccessible parts such as purlins of which only three faces can be covered by the heating elements which will then be held in place if possible by straps or clamps. The temperature control program will take into account this particular feature of the heating element placement.

Claims (6)

1 °) Process for heat treatment of wooden pieces by heat, against parasites, process characterized in that: the parts to be treated are wrapped with an electric heating element whose external surface has good thermal insulation characteristics, by closely covering the part to be treated, - a temperature profile is controlled as a function of time to drive the core of the part to be treated to a determined temperature, guaranteeing the destruction of parasites inside the wood, - the temperature profile is determined as a function of the nature and age of the wood, of hygrometry as well as of the section of the part to be treated, - The supply of alternately the different heating elements is preferably controlled using a control station and at the end of the treatment, each heating element is removed. 2) Method according to claim 1, characterized in that the different heating elements are fed in a nested fashion. 3) Installation for heat treatment of wood against parasites, for implementing the method according to claim 1, installation characterized in that it comprises: - a set of electric heating elements in the form of sheets (1-4, 200, 300) whose inner surface is heated and the outer surface is insulating, these elements being provided with electrical connection means (11-14, 207, 307 ), - an electrical supply unit (15) to which the heating elements (1-4) are connected, this unit regulating the electrical supply of the heating elements as a function of a predetermined temperature and by multiplexing the supply of the elements (1-4, 200, 300) when several elements are in service simultaneously, - a control panel (16) equipped with a microcomputer for managing the temperature curves of the heating element or elements according to a given program, - temperature sensors (21-24, 205, 206, 310, 311, 312) associated with each element to detect the temperature of the part to be treated, this temperature information being transmitted to the control panel (16) which controls the corresponding heating element temperature curve as a function of this information and of parameters related to the material of the part and to its dimensions. 4 °) Installation according to claim 3, characterized in that the heating element (200) is rectangular. 5 °) Installation according to claim 3, characterized in that the heating element (300) is T-shaped. 6 °) Installation according to claim 3, characterized in that the heating element (200, 300) has fasteners (201, 202, 203, 204, 303, 304, 305, 306).

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