EP1612016A1 - Process and apparatus for wood impregnation - Google Patents

Abstract

The method involves inserting a wood (21) in a tank (11) where it is heated by immersing in hot oil (13). A cold oil (14) contained in a tank (12) is substituted for the hot oil in the tank (11) when the wood attains sufficient temperature. The hot oil is at 100[deg] to 160[deg] Celsius, and the cold oil is at 60[deg] Celsius. The tanks are connected at their top parts by a spillage circuit (2) and at their bottom parts by a pumping circuit (3). An independent claim is also included for a device for treating wood.

Description

The present invention relates to a method of treating wood by heating and immersion in a treatment product. The present invention further relates to a device for implementing such a method. Such a method is particularly suitable for treating chestnut wood.

Such processes exist in which wood is available in a tank filled with oil. The oil is heated. The oil bath is then allowed to cool. The wood impregnates the oil during cooling. However, given the duration of each of the steps, including the time of cooling the oil, such a process has a low yield.

This problem is solved by Document FR 2 810 917 using two tanks, one for heating and the other for treatment. However, this involves removing the wood from one tank to the other, which has the disadvantage of exposing the heated wood to air before its introduction into the treatment tank.

FR 2 801 241 discloses another treatment method, also using two separate baths for heating and treating wood, and having the same drawback of exposing the wood to the air during its passage from a bath to the other.

The object of the invention is to provide a method and an associated device to allow a wood treatment with a significantly improved performance.

According to the invention, such a wood treatment method comprises a step of heating the wood and then a step during which the wood is immersed in a treatment product. It is characterized in that the wood is introduced into a tank where the wood is heated by immersion in a heating product at high temperature, and then that the treatment product is then replaced in said tank. heating product, said treatment product being at a low temperature. Thus, according to the invention, during the entire duration of the treatment, the wood is never contact with the ambient air. The entire cycle can therefore be performed in a liquid medium.

According to the invention, such a device for treating wood comprises a tank for immersing said wood, storage means for a heating product, storage means for a treatment product, means for substituting one for other in the tank the treatment product and the heating product. Advantageously, the storage means for the heating product and the treatment product are one and the same other tank. More advantageously still, this other tank can constitute a tank for the treatment of other wood.

Other features and advantages of the invention will emerge from the description below, relating to non-limiting examples.

• la figure 1 est une représentation schématique et en coupe d'un dispositif selon l'invention ;
• Les figures 2 à 9 illustrent des étapes d'un procédé selon l'invention, mis en oeuvre dans le dispositif de la figure 1 ;
• La figure 10 illustre schématiquement et en coupe une le circuit de déversement pour le dispositif de la figure 1 ; et,
• La figure 11 est une coupe schématique illustrant des aménagements avantageux pour une cuve utilisable dans un dispositif selon l'invention.

In the accompanying drawings:

• Figure 1 is a schematic representation in section of a device according to the invention;
• Figures 2 to 9 illustrate steps of a method according to the invention, implemented in the device of Figure 1;
• Figure 10 illustrates schematically and in section a spill circuit for the device of Figure 1; and,
• Figure 11 is a schematic section illustrating advantageous arrangements for a tank used in a device according to the invention.

Figure 1 shows a processing device 1 for wood. This device comprises a first tank 11 and a second tank 12. The two tanks are interconnected, in their upper part by a discharge circuit 2, and in their lower part, by a pumping circuit 3, equipped with pumping means. 6, for example a pump. The device 1 is provided for the treatment of wood 4 by impregnation of oil. A batch of wood 21 is placed in a basket 5. Here, for example, the wood batch consists of boards 4.

The basket 5 allows to have several boards 4 separated from each other so that when immersed in an oil bath, each is suitably surrounded by oil. In addition, the basket allows to handle a large number of boards simultaneously.

In Figure 1, the first tank 11 contains hot oil 13 illustrated by simple hatching, and the second tank 12 contains cold oil, illustrated by double hatching in broken lines. In FIG. 1, the basket 5 is immersed with its batch of wood 21 in the hot oil of the first tank 11, while the cold oil is stored in the second tank 12. The temperature of the hot oil is higher at 100 ° C, preferably it is about 100 ° C to 160 ° C, and the temperature of the cold oil is less than 95 ° C, preferably about 60 ° C.

In the configuration of Figure 1, the wood is heated by the hot oil. When the wood has reached a sufficient temperature, generally after a given time, the device 1 makes it possible to substitute the cold oil for the hot oil in the first tank, the hot oil then being stored in the second tank 12 in the place previously occupied by the cold oil. Resistors 7 can maintain the temperature of the hot oil in the tank that contains it. The tanks comprise setting means 10 for holding the basket 5 above the resistors 7.

While in previous processes, it is the same oil that is used to heat the wood and which is impregnated in the wood while cooling, it is not useful to wait for the oil bath to cool so that the impregnation is done. Thus, according to the invention, the wood is immersed in already cold oil, and the impregnation is faster.

The device 1 is designed symmetrically, so that the first and second tanks are identical and can indifferently be used for storing oils or treating wood.

An impregnation method using such a device for the simultaneous treatment of two batches of wood will now be described with reference to Figures 2 to 9. Such a method, using the two tanks for the treatment of wood, can further increase the yield.

In a first step, illustrated in FIG. 2, the oils are distributed as previously described with reference to FIG. 1. A first batch of wood 21 is being heated in the first tank 11, and a second batch of wood is introduced. 22 in the second tank 12.

In a second step, illustrated in Figure 3, when the first batch 21 is hot, the oils are substituted between them. For this, pumping means are used to pump the cold oil from the bottom of the second tank in a first direction A, through the pumping circuit, into the bottom of the first tank 11. Of a density more high that the hot oil 13, the cold oil 14 is substituted from below to the hot oil, without mixing.

Driven by the cold oil, the hot oil flows from the top, through the discharge circuit, into the second tank 12. The density of the hot oil is lower than that of the cold oil, it s replace it with cold oil, without mixing with it.

The second step being completed, we are in the configuration of Figure 4. Figure 4 illustrates a third step during which the first batch is impregnated with cold oil 14, in the first tank 11, while the second batch is heated by the hot oil 13 in the second tank 12.

Figure 5 illustrates a fourth step. The first batch 21 is sufficiently impregnated is then removed from the first tank 11. In a fifth step, a third batch of wood 23 is then introduced into the first tank thus released, as shown in Figure 6.

We then find ourselves in the arrangement of FIG. 7, symmetrical to that of FIG. 3, and the following steps, that is to say the sixth, seventh and eighth steps, are respectively similar to the second, third and fourth stages, these the last being respectively illustrated in Figures 7 to 9.

Thus, in the sixth step when the second batch is sufficiently hot, the oils are substituted between them by pumping the cold oil 14 from the bottom of the first tank 11 to the bottom of the second tank. The cold oil is pumped through the pumping duct, in the direction B, the reverse of the direction A, as shown in Figure 7. The pumping means 6 are here reversible.

In the seventh step, as illustrated in FIG. 8, the third batch 23 is heated while the second batch 22 impregnates with cold oil while cooling.

In the eighth step, illustrated in Figure 9, the second batch 22, when sufficiently impregnated, is removed from the second tank 12, leaving room for a possible fourth batch of wood.

It is then in the arrangement of Figure 1, ready to resume the process in the first step as illustrated in Figure 2.

As explained above, the circulation of the hot oil is done by the top of the tanks, through the spill circuit 2, and the circulation of the cold oil is from below, through the pumping circuit 3.

The spill circuit will first be described with reference to FIG. 10. This figure represents a longitudinal section of the spill circuit, and partially from the top of the tanks, in the vicinity of their junctions with the spill circuit 2, in the configuration. of Figure 2, for which the hot oil flows from the first tank 11 to the second tank 12.

The circuit 2 comprises a U-shaped tubular siphon 51. The siphon 51 comprises, at each of its ends, a horizontal discharge ramp 52 extending along one side of each of the tanks 11, 12. The siphon opens from below, through the ramp 52. Each ramp 52 and its respective tank, are separated by a breakwater wall 53, an upper flange 54 is horizontal. Preferably, the upper arches of the breakwater walls of each end of the discharge circuit, its level between them.

Thus, the hot oil 13 leaving the siphon spreads on the ramp 52 before crossing the upper edge 54 of the breakwater wall 53. Thus, for a given oil flow in the discharge circuit 2, the spill rate of the hot oil in the tank 12 is substantially zero. This limits the risk of turbulence.

In addition, the device comprises means (not shown) for maintaining the upper level of oil, in each of the tanks, close to the level of the upper plate 54, in particular to prevent a fall of the hot oil 13 since the discharge circuit 2 in lower cold oil 14 in the second tank 12, causes their mixing, at the beginning of substitution. Likewise, since the level of the oil in the first tank 11 is not appreciably greater than the respective level 54, there is little risk, at the end of the substitution, of the cold oil 14, which is substituted. from the bottom to the hot oil 13 in the first tank 11, enters the discharge circuit 2.

Of course, the operation of the device being symmetrical in the example described, the discharge circuit is also symmetrical, and in a reverse operation, the terms of the first tank and two second tank can be interchanged.

Figure 11 is a schematic section on a tank 11,12. In order to maintain the temperature of the liquids, the walls 40 of this tank comprise an insulator 41. In the example of FIG. 12, this insulator is compressed wool, for example rock wool or compressed glass wool.

This insulator 41 constitutes the carrying structure of the tank. The insulator is lined internally with sheet 43, forming a seal for the liquids. A sheet 42 constitutes the outer covering of the insulation 41.

The tank shown in FIG. 11 also comprises a product inlet 44 entering the tank through its bottom 26. The product inlet constitutes an end of the pumping circuit 3. The arrival of product is surmounted by a deflector 45. This deflector is intended for the treatment product entering the tank through said inlet 44 is spread in the tank along the bottom in the direction F. Thus, the treatment product arrives in the tank without causing a stir in the product already present in the tank. Turbulence is thus limited, as well as the risks of mixing hot oil and cold oil, especially at the beginning of substitution.

In addition, the arrival of product being through the bottom, when removing the cold oil, the oil is taken closer to the bottom. Thus, at the end of substitution, there is little risk that hot oil, which substitutes itself from above for cold oil, enters the pumping circuit 3.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

Thus, the hot oil as used in the example described serves essentially as a heating liquid for wood. Thus, it could easily be replaced by another heating product.

A drier can also be used for cold oil, thus enhancing the immiscibility of cold oil with hot oil.

Rather than oil, another impregnation product may also be chosen. Preferably, impregnating and treatment products which are not miscible with each other at their respective temperature of use, each of which fulfills a different function in a different phase of the process according to the invention, will be chosen.

Unlike the example described, the heating product can have the highest density, and be substituted by the bottom of the tanks.

The temperatures of the heating or treatment liquid may vary, in particular depending on the type of treated wood, the geometry of the wood pieces and the liquids used.

Claims (19)

A method of treating wood (21,23) comprising a step of heating the wood (21,23) then a step during which the wood is immersed in a treatment product (14), characterized in that the wood is introduced in a tank (11) where the wood is heated by immersion in a heating product (13) at high temperature, and then that the treatment product (14) is then replaced in said tank (11) with heating product (13), said treatment product being at a low temperature. Process according to claim 1, characterized in that when the treatment product is substituted for the heating product in said tank (11), the same heating product is simultaneously substituted for the same treatment product in another tank (12). for the treatment of other wood (22). Process according to claim 1 or 2, characterized in that an oil is used as a treatment product. Process according to one of Claims 1 to 3, characterized in that an oil is used as a heating product. Process according to one of Claims 1 to 3, characterized in that an exager is used for the treatment product. Device for treating wood (21,23), comprising a treatment tank (11) for immersing said wood (21,23), storage means (12) for a heating product (13), storage means ( 12) for a treatment product (14), means for substituting (2,3,6) for each other in the vessel (11) the treatment product and the heating product. Device according to claim 6, characterized in that the treatment tank (11) is a first tank (11) and in that the storage means (12) for the heating product and the treatment product are one and the same. second tank (12). Device according to claim 6 or 7 characterized in that the second tank (12) is a tank for the treatment of other wood (22). Device according to claim 8, characterized in that it comprises a pumping circuit (3) comprising pumping means (6) for one of the treatment product or the heating product. Device according to claim 9, characterized in that the pumping means are reversible. Device according to one of claims 10 or 11, characterized in that the pumping circuit connects the bottom of the first tank with the bottom of the second tank. Device according to claim 11, characterized in that the pumping circuit comprises at an end connected to the bottom of one of the tanks, a product inlet (44), said product inlet being surmounted by a deflector (45). Device according to one of claims 9 to 12, characterized in that it comprises a discharge circuit (2) of the other of the treatment product or the heating product. Device according to claim 13, characterized in that the discharge circuit connects the top of the first tank with the top of the second tank. Device according to claim 14, characterized in that the discharge circuit comprises at one end (19) penetrating into one of the tanks, a discharge ramp (52) extending along one side of said vessel. Device according to claim 15, characterized in that the discharge circuit comprises between the tank and the discharge ramp, a breakwater wall (53). Device according to Claim 16, characterized in that it comprises means for maintaining the level of product in the vessel near the level of a horizontal upper level (54) of the breakwater wall (53). Vat for the treatment of wood, characterized in that its walls have a supporting structure (41) of compressed wool forming insulation. Vessel according to claim 18, characterized in that the carrier structure (41) is clad with sheet metal (42,43).

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