EP0854776B1 - Wood curing method - Google Patents
Wood curing method Download PDFInfo
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- EP0854776B1 EP0854776B1 EP97935631A EP97935631A EP0854776B1 EP 0854776 B1 EP0854776 B1 EP 0854776B1 EP 97935631 A EP97935631 A EP 97935631A EP 97935631 A EP97935631 A EP 97935631A EP 0854776 B1 EP0854776 B1 EP 0854776B1
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- Prior art keywords
- wood
- gases
- hemicellulose
- treatment
- enclosure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
- B27K5/0085—Thermal treatments, i.e. involving chemical modification of wood at temperatures well over 100°C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K2240/00—Purpose of the treatment
- B27K2240/70—Hydrophobation treatment
Definitions
- the present invention relates to an improvement high temperature wood treatment processes and in particular to so-called retification treatments.
- drying step removes water from the wood it does not change anything against the character hydrophilic of it, so that it is again suitable to reabsorb the water eliminated during drying when it again found in a humid atmosphere.
- the object of the present invention is to overcome this disadvantage by proposing a method allowing detect the end of the processing stage of the Retification.
- the wood is placed in a processing enclosure provided a sensor sensitive to acetic acid and / or dioxide carbon and / or carbon monoxide.
- temperature T in ° C
- time t in min
- Such a treatment process includes three stages, namely a drying stage A, a stage of glass transition B, and a crosslinking step proper C.
- the first drying step A breaks down into two phases, a first phase A 1 during which the temperature of the drying chamber containing the ash to be treated is gradually raised with a rate of temperature rise of approximately 5 ° C / min, from ambient temperature to a temperature T 1 , close to 100 ° C, followed by a phase A 2 during which the temperature of the enclosure is maintained at the level T 1 until the end of drying.
- the temperature of the enclosure is gradually raised, with a rate of temperature increase close to the previous one, from the temperature T 1 to a temperature T g of 170 ° C close to the glass transition temperature of the species of wood considered, namely ash in this case.
- the temperature T g is maintained at this plateau value for the time necessary for the entire mass of treated wood to reach the glass transition temperature T g . It will be noted that the fact of extending the duration of this plateau does not have any harmful consequences with regard to compliance with the mechanical qualities of the product treated.
- the temperature of the enclosure is gradually raised, during a phase C 1 , with a temperature rise speed close to the previous rise speed, from the glass transition temperature T g from 170 ° C up to the retification temperature T r from 230 ° C and the oven temperature is maintained for a second phase C 2 at this plateau value, until a high proportion of hemicellulose is broken down.
- FIG. 2 shows a graph consisting of two series of curves which have been superimposed.
- a first curve (reference I) represents the variation ⁇ m / ⁇ t of the mass loss ⁇ m of the treated wood as a function of time, during the complete retification process.
- a second series of curves represents the variation of absorbance A as a function of time, in the infrared domain, during the same treatment process, characteristic of the release of three gases from the decomposition of hemicellulose, namely acetic acid (curve II a ), carbon dioxide (curve II b ) and carbon monoxide (curve II c ).
- the quantity of one or more of the gases produced by the decomposition of the hemicellulose is monitored, in order to detect the instant t a which corresponds to the moment when there is no longer any decomposition of the hemicellulose. and which therefore indicates that the crosslinking reaction is complete.
- This monitoring can be carried out by means of known type sensors which, on the one hand, are able to detect specific gases produced by the decomposition of hemicellulose, especially acid acetic, carbon dioxide, or carbon monoxide and, on the other hand, are able to withstand processing temperatures.
- We can also use jointly several sensors which are specifically each sensitive to one of the gases and whose signals are processed by electronic means, so as to achieve a possibly weighted average of the measurements performed by each sensor.
- We can preferentially use a sensor sensitive to both three gases above which simplifies signal processing provided.
- One can of course also appeal, for carry out monitoring, at a measurement chain gas analysis, in particular by spectrography infrared.
- the Applicant has established that a certain type of sensors is particularly interesting to put in implements the treatment method according to the invention.
- the sensors of this type have a sensitive element which consists of a metal oxide, and more particularly a metal oxide of the type allowing detection of reducing gases. We will thus retain everything particularly sensors whose sensitive element is made of tin dioxide. We can also use sensors whose sensitive element consists of titanium dioxide or zinc oxide.
- a processing operation will be described below. of captivating pieces of wood which is set work according to the invention, that is to say by controlling the end of the retification phase proper by the detection of when hemicellulose is destroyed in most of it.
- the whole treatment includes a stage of drying A which is itself followed by a step of glass transition B and a crosslinking step C which is controlled according to the invention with a sensor of the type of the one described above.
- the signal produced by the sensor at during the retification phase is a function of the nature of treated wood.
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- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Chemical And Physical Treatments For Wood And The Like (AREA)
- Drying Of Solid Materials (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
La présente invention concerne un perfectionnement aux procédés de traitement du bois à haute température et notamment aux traitements dits de rétification.The present invention relates to an improvement high temperature wood treatment processes and in particular to so-called retification treatments.
On sait, qu'à l'état naturel, le bois ou les fibres de bois qui sont au contact d'une atmosphère humide ont tendance à se gorger d'eau, allant jusqu'à absorber 100% de leur poids de celle-ci. Cette absorption d'eau s'accompagne d'une part d'un gonflement et d'autre part d'une perte des qualités mécaniques et des qualités de cohésion du matériau, pouvant aller dans certains cas jusqu'à une désagrégation avancée de celui-ci. C'est pourquoi on a pour habitude de faire précéder toute étape d'usinage du bois d'une étape de séchage qui, en éliminant l'eau de celui-ci, améliore sa stabilité dimensionnelle.We know that in its natural state, wood or fibers of wood which are in contact with a humid atmosphere have tendency to soak up water, up to absorb 100% of their weight from it. This water absorption is accompanied on the one hand by swelling and on the other hand loss of mechanical qualities and qualities of cohesion of the material, which can go in certain cases until an advanced disintegration of it. It is why we are used to precede any step woodworking of a drying step which, in removing water from it, improving its stability dimensional.
Si l'étape de séchage permet d'éliminer l'eau du bois elle ne modifie en rien par contre le caractère hydrophile de celui-ci, si bien qu'il est de nouveau apte à réabsorber l'eau éliminée lors du séchage lorsqu'il se trouve de nouveau en atmosphère humide.If the drying step removes water from the wood it does not change anything against the character hydrophilic of it, so that it is again suitable to reabsorb the water eliminated during drying when it again found in a humid atmosphere.
Afin de diminuer le caractère hydrophile du bois naturel et de lui conférer ainsi une stabilité dimensionnelle durable, on a proposé différentes techniques de traitement thermique à haute température. In order to reduce the hydrophilic character of the wood natural and thus give it stability dimensional dimension, we proposed different high temperature heat treatment techniques.
Parmi ces techniques, on a proposé de faire subir au bois naturel différentes étapes de traitement comprenant notamment un séchage en circuit ouvert suivi d'un chauffage et d'un maintien à une température comprise entre environ 220°C et 300°C pendant une période déterminée. Une telle technique de traitement, dite de rétification, permet de conférer au bois à la fois un caractère hydrophobe et une excellente stabilité dimensionnelle.Among these techniques, it has been proposed to subject the natural wood different stages of treatment including in particular an open circuit drying followed by a heating and maintaining at a temperature included between about 220 ° C and 300 ° C for a period determined. Such a treatment technique, called cross-linking, gives the wood both hydrophobic character and excellent stability dimensional.
Un tel procédé est décrit dans la demande de brevet FR-A-2 720 969.Such a process is described in the application FR-A-2 720 969.
On a cependant constaté que l'opération de rétification devait être menée avec la plus grande rigueur sous peine de diminuer les caractéristiques mécaniques du bois traité. On sait en effet que cette étape de rétification a pour objet de détruire en partie l'hémicellulose du bois sans pour autant porter atteinte à la structure de celui-ci, autrement dit sans détruire la lignine.However, it was found that the operation of retification had to be carried out with the greatest rigor under penalty of reducing the characteristics mechanics of treated wood. We know that this the purpose of retification is to partially destroy wood hemicellulose without compromising to the structure of it, in other words without destroying lignin.
Dans ces conditions l'une des difficultés majeures rencontrée lors du traitement de rétification consiste à déterminer la durée pendant laquelle on doit maintenir la température de rétification pour détruire l'hémicellulose sans détruire, de façon significative, la lignine.Under these conditions one of the major difficulties encountered during cross-linking treatment consists of determine how long you should maintain the crosslinking temperature to destroy hemicellulose without significantly destroying the lignin.
La présente invention a pour but de pallier à cet inconvénient en proposant un procédé permettant de détecter la fin du palier de traitement de la phase de rétification. The object of the present invention is to overcome this disadvantage by proposing a method allowing detect the end of the processing stage of the Retification.
Il est en conséquence proposé un procédé
suivant la revendication 1.A method is therefore proposed.
according to
Dans un mode de mise en oeuvre de l'invention, le bois est disposé dans une enceinte de traitement munie d'un capteur sensible à l'acide acétique et/ou au dioxyde de carbone et/ou à l'oxyde de carbone.In one embodiment of the invention, the wood is placed in a processing enclosure provided a sensor sensitive to acetic acid and / or dioxide carbon and / or carbon monoxide.
D'autres caractéristiques sont définies dans les revendications dépendantes.Other features are defined in the dependent claims.
On décrira ci-après, à titre d'exemple non
limitatif, une forme d'exécution de la présente
invention, en référence au dessin annexé sur lequel :
Sur la figure 1, on a ainsi représenté la variation de température T (en °C) en fonction du temps t (en min), à laquelle on a porté une enceinte contenant du bois à traiter, constitué par du frêne, au cours d'un processus de rétification.In FIG. 1, the variation has thus been represented temperature T (in ° C) as a function of time t (in min), to which an enclosure containing wood was brought to treat, consisting of ash, during a process of retification.
Un tel processus de traitement comprend trois étapes, à savoir une étape de séchage A, une étape de transition vitreuse B, et une étape de rétification proprement dite C.Such a treatment process includes three stages, namely a drying stage A, a stage of glass transition B, and a crosslinking step proper C.
La première étape de séchage A se décompose elle-même en deux phases, une première phase A1 au cours de laquelle on élève progressivement la température de l'enceinte de séchage contenant le frêne à traiter avec une vitesse de montée en température d'environ 5°C/min, à partir de la température ambiante jusqu'à une température T1, voisine de 100°C, suivie d'une phase A2 au cours de laquelle on maintient la température de l'enceinte à la valeur palier T1 jusqu'à la fin du séchage.The first drying step A breaks down into two phases, a first phase A 1 during which the temperature of the drying chamber containing the ash to be treated is gradually raised with a rate of temperature rise of approximately 5 ° C / min, from ambient temperature to a temperature T 1 , close to 100 ° C, followed by a phase A 2 during which the temperature of the enclosure is maintained at the level T 1 until the end of drying.
Au cours de la seconde étape B, on élève progressivement la température de l'enceinte, avec une vitesse de montée en température voisine de la précédente, à partir de la température T1 jusqu'à une température Tg de 170°C voisine de la température de transition vitreuse de l'essence de bois considérée, à savoir le frêne dans le cas présent. On maintient la température Tg à cette valeur palier pendant le temps nécessaire pour que la totalité de la masse de bois traité atteigne la température de transition vitreuse Tg. On remarquera que le fait de prolonger la durée de ce palier ne se traduit par aucune conséquence néfaste en ce qui concerne le respect des qualités mécaniques du produit traité.During the second step B, the temperature of the enclosure is gradually raised, with a rate of temperature increase close to the previous one, from the temperature T 1 to a temperature T g of 170 ° C close to the glass transition temperature of the species of wood considered, namely ash in this case. The temperature T g is maintained at this plateau value for the time necessary for the entire mass of treated wood to reach the glass transition temperature T g . It will be noted that the fact of extending the duration of this plateau does not have any harmful consequences with regard to compliance with the mechanical qualities of the product treated.
Au cours de la troisième étape C on élève progressivement, au cours d'une phase C1, la température de l'enceinte avec une vitesse de montée en température voisine de la vitesse de montée précédente, à partir de la, température de transition vitreuse Tg de 170°C jusqu'à la température de rétification Tr de 230°C et l'on maintient pendant une seconde phase C2 la température du four à cette valeur palier, jusqu'à ce qu'une forte proportion d'hémicellulose soit décomposée.During the third step C, the temperature of the enclosure is gradually raised, during a phase C 1 , with a temperature rise speed close to the previous rise speed, from the glass transition temperature T g from 170 ° C up to the retification temperature T r from 230 ° C and the oven temperature is maintained for a second phase C 2 at this plateau value, until a high proportion of hemicellulose is broken down.
On sait qu'une des difficultés de cette phase spécifique réside dans le fait que le maintien en température doit s'effectuer pendant un temps suffisamment long pour qu'un fort pourcentage d'hémicellulose soit décomposé, mais qu'il est impératif de ne pas dépasser ce temps, sous peine de commencer à détruire du même coup la lignine, ce qui se traduirait alors par une chute des caractéristiques mécaniques du bois traité.We know that one of the difficulties of this phase specific is that maintaining temperature must be carried out for a time long enough for a large percentage hemicellulose is broken down, but it is imperative not to exceed this time, on pain of starting to destroy lignin at the same time, which would result then by a fall in the mechanical characteristics of the treated wood.
On a représenté sur la figure 2 un graphique constitué de deux séries de courbes que l'on a superposées. Une première courbe (référence I) représente la variation Δm/Δt de la perte de masse Δm du bois traité en fonction du temps, au cours du processus complet de rétification. Une seconde série de courbes représente la variation d'absorbance A en fonction du temps, dans le domaine de l'infrarouge, au cours du même processus de traitement, caractéristique d'un dégagement de trois gaz provenant de la décomposition de l'hémicellulose, à savoir l'acide acétique (courbe IIa), le dioxyde de carbone (courbe IIb) et l'oxyde de carbone (courbe IIc).FIG. 2 shows a graph consisting of two series of curves which have been superimposed. A first curve (reference I) represents the variation Δm / Δt of the mass loss Δm of the treated wood as a function of time, during the complete retification process. A second series of curves represents the variation of absorbance A as a function of time, in the infrared domain, during the same treatment process, characteristic of the release of three gases from the decomposition of hemicellulose, namely acetic acid (curve II a ), carbon dioxide (curve II b ) and carbon monoxide (curve II c ).
En ce qui concerne la variation de la masse du bois traité représentée par la courbe I, on constate la présence de deux pics qui sont caractéristiques de première part de la perte de masse due au séchage du bois et de seconde part de la perte de masse due à la décomposition de l'hémicellulose. On constate également sur cette figure qu'il y a coïncidence du second pic correspondant à la chute de masse la plus élevée (courbe I) et des trois pics caractéristiques de l'acide acétique (courbe IIa), du dioxyde de carbone (courbe IIb) et de l'oxyde de carbone (courbe IIc) produits.Regarding the variation of the mass of the wood treated represented by curve I, we note the presence of two peaks which are characteristic of first part of the mass loss due to wood drying and second part of the mass loss due to the decomposition of hemicellulose. We also see in this figure that there is coincidence of the second peak corresponding to the highest mass drop (curve I) and of the three characteristic peaks of acetic acid (curve IIa), carbon dioxide (curve IIb) and carbon monoxide (curve IIc) produced.
Suivant la présente invention on surveille la quantité de l'un ou de plusieurs des gaz produits par la décomposition de l'hémicellulose, afin de détecter l'instant ta qui correspond au moment où il n'y a plus décomposition de l'hémicellulose et qui indique donc que la réaction de rétification est terminée.According to the present invention, the quantity of one or more of the gases produced by the decomposition of the hemicellulose is monitored, in order to detect the instant t a which corresponds to the moment when there is no longer any decomposition of the hemicellulose. and which therefore indicates that the crosslinking reaction is complete.
Cette surveillance peut être effectuée au moyen de capteurs de type connu qui, d'une part, sont en mesure de détecter les gaz spécifiques produits par la décomposition de l'hémicellulose, et notamment de l'acide acétique, du dioxyde de carbone, ou de l'oxyde de carbone et, d'autre part, sont en mesure de résister aux températures du traitement. On peut également utiliser conjointement plusieurs capteurs qui sont spécifiquement sensibles chacun à l'un des gaz et dont les signaux sont traités par des moyens électroniques, de façon à réaliser une moyenne éventuellement pondérée des mesures effectuées par chaque capteur. On peut préférentiellement utiliser un capteur sensible à la fois aux trois gaz susmentionnés ce qui simplifie le traitement du signal fourni. On peut également bien entendu faire appel, pour effectuer la surveillance, à une chaíne de mesure d'analyse des gaz, notamment par spectrographie infrarouge.This monitoring can be carried out by means of known type sensors which, on the one hand, are able to detect specific gases produced by the decomposition of hemicellulose, especially acid acetic, carbon dioxide, or carbon monoxide and, on the other hand, are able to withstand processing temperatures. We can also use jointly several sensors which are specifically each sensitive to one of the gases and whose signals are processed by electronic means, so as to achieve a possibly weighted average of the measurements performed by each sensor. We can preferentially use a sensor sensitive to both three gases above which simplifies signal processing provided. One can of course also appeal, for carry out monitoring, at a measurement chain gas analysis, in particular by spectrography infrared.
La demanderesse a établi qu'un certain type de capteurs est particulièrement intéressant pour mettre en oeuvre le procédé de traitement suivant l'invention. Les capteurs de ce type comportent un élément sensible qui est constitué d'un oxyde métallique, et plus particulièrement d'un oxyde métallique du type permettant la détection des gaz réducteurs. On retiendra ainsi tout particulièrement les capteurs dont l'élément sensible est constitué de dioxyde d'étain. On peut également utiliser des capteurs dont l'élément sensible est constitué de dioxyde de titane ou d'oxyde de zinc.The Applicant has established that a certain type of sensors is particularly interesting to put in implements the treatment method according to the invention. The sensors of this type have a sensitive element which consists of a metal oxide, and more particularly a metal oxide of the type allowing detection of reducing gases. We will thus retain everything particularly sensors whose sensitive element is made of tin dioxide. We can also use sensors whose sensitive element consists of titanium dioxide or zinc oxide.
Sur la figure 3, on a représenté, sur un même graphique, d'une part l'absorbance A de l'acide acétique (courbe I), du dioxyde de carbone (courbe II) et de l'oxyde de carbone (courbe III) au cours d'une étape de rétification proprement dite de morceaux de hêtre et, d'autre part, le signal S en volts (courbe IV) produit par un capteur de l'état antérieur de la technique qui est disposé dans l'enceinte de traitement. On constate sur la figure 3 que le maximum du signal S fourni par le capteur coïncide sensiblement avec les maxima des courbes d'absorbance de l'acide acétique, du dioxyde de carbone et de l'oxyde de carbone, avec cependant un léger retard, ce qui permet à l'utilisateur, lorsqu'il détecte le maximum du signal S donné par son capteur, d'être sûr que l'hémicellulose est bien décomposée.In Figure 3, there is shown, on the same graph, on the one hand the absorbance A of acetic acid (curve I), carbon dioxide (curve II) and carbon monoxide (curve III) during a step of proper retification of beech pieces and, on the other hand, the signal S in volts (curve IV) produced by a sensor of the prior art which is placed in the processing enclosure. We aknowledge in FIG. 3 that the maximum of the signal S supplied by the sensor substantially coincides with the maxima of the curves absorbance of acetic acid, carbon dioxide and carbon monoxide, with a slight delay, which allows the user, when he detects the maximum of the signal S given by its sensor, to be sure that the hemicellulose is well broken down.
On décrira ci-après une opération de traitement thermique de morceaux de bois de charme qui est mise en oeuvre suivant l'invention, c'est-à-dire en contrôlant la fin de la phase de rétification proprement dite par la détection du moment où l'hémicellulose est détruite dans sa plus grande partie.A processing operation will be described below. of charming pieces of wood which is set work according to the invention, that is to say by controlling the end of the retification phase proper by the detection of when hemicellulose is destroyed in most of it.
L'ensemble du traitement comprend une étape de séchage A qui est elle-même suivie d'une étape de transition vitreuse B et d'une étape de rétification C que l'on contrôle suivant l'invention avec un capteur du type de celui décrit précédemment.The whole treatment includes a stage of drying A which is itself followed by a step of glass transition B and a crosslinking step C which is controlled according to the invention with a sensor of the type of the one described above.
Sur la figure 4, on n'a représenté que l'étape de rétification C proprement dite. On a ainsi porté sur un même graphique et en fonction du temps, d'une part la variation de la température T de l'enceinte de traitement (en traits pointillés) et d'autre part, le signal S (en volts) fourni par le capteur (en traits pleins). On a, suivant l'invention, arrêté la phase de rétification proprement dite à l'instant ta où le signal S du capteur passe par un maximum, c'est-à-dire que l'on a interrompu le chauffage pour laisser la température descendre.In FIG. 4, only the crosslinking step C proper has been shown. We have thus drawn on the same graph and as a function of time, on the one hand the variation of the temperature T of the treatment enclosure (in dotted lines) and on the other hand, the signal S (in volts) supplied by the sensor (in solid lines). According to the invention, the retification phase proper was stopped at time t a when the signal S of the sensor passes through a maximum, that is to say that the heating was interrupted to allow the temperature go down.
Des mesures effectuées sur le bois de charme ainsi traité ont confirmé qu'une partie importante de l'hémicellulose est bien décomposée, ce qui garantit l'efficacité de la rétification, et que la lignine n'est pas en encore attaquée, ce qui garantit la conservation des qualités mécaniques du bois traité. Ces mesures sont regroupées dans le tableau ci-après.Measurements made on hornbeam as well treaty have confirmed that a significant portion of the hemicellulose is well broken down, which guarantees the effectiveness of cross-linking, and that lignin is not not yet under attack, which guarantees conservation mechanical qualities of treated wood. These measures are grouped in the table below.
On a dosé les pentosanes qui représentent la plus
grande partie des hémicelluloses de ce bois et l'on a
constaté, que de l'état naturel à l'état rétifié, leur
pourcentage passait de 25,6% à 15,9%, ce qui représente
une diminution de 37%.
On a également dosé les lignines et l'on a constaté qu'il n'y avait pas destruction de celles-ci, ce qui garantit le maintien des qualités mécaniques du bois traité. On constate également que la densité ne diminue que faiblement, passant de 0,75 à 0,67, ce qui représente une diminution de l'ordre de 10%.We also measured the lignins and we found that there was no destruction of these, which guarantees the maintenance of the mechanical qualities of the wood treaty. We also note that the density does not decrease only slightly, going from 0.75 to 0.67, which represents a decrease of around 10%.
On a également effectué le même traitement sur une autre essence de bois, à savoir le pin, et l'on a reporté les résultats dans le tableau ci-dessus. Ces résultats confirment en tous points ceux obtenus pour le charme.We also performed the same treatment on a other wood species, namely pine, and we have postponed the results in the table above. These results confirm in all points those obtained for the charm.
De façon intéressante, on pourra associer au capteur des moyens électroniques d'analyse du signal qui détecteront toute valeur nulle ou toute inversion de la pente de la courbe représentative du signal S produit au cours du traitement.Interestingly, we can associate with the sensor electronic means of signal analysis which will detect any null value or any inversion of the slope of the curve representative of the signal S produced at during treatment.
Bien entendu, le signal produit par le capteur au cours de la phase de rétification est fonction de la nature du bois traité. On a ainsi représenté sur la figure 5, la variation du signal S produit par le même capteur, dans le cas d'un traitement de rétification effectué sur du pin (courbe a) et du même traitement effectué sur du hêtre (courbe b).Of course, the signal produced by the sensor at during the retification phase is a function of the nature of treated wood. We have thus represented on the Figure 5, the variation of the signal S produced by the same sensor, in the case of cross-linking treatment made on pine (curve a) and the same treatment made on beech (curve b).
On constate sur cette figure que si le pic caractéristique des signaux respectifs produits par le capteur est moins marqué dans le cas du pin que dans le cas du hêtre, il est néanmoins facile de détecter l'annulation de la pente ou son inversion définissant l'instant ta où le palier de rétification doit être interrompu.We can see in this figure that if the peak characteristic of the respective signals produced by the sensor is less marked in the case of pine than in the beech, it is nevertheless easy to detect the cancellation of the slope or its inversion defining the instant ta when the retification level must be interrupted.
Claims (8)
- Method for treating wood by heating, comprising at least one stage in which the wood to be treated is held in a treatment enclosure at a defined temperature in such a way as to destroy, at least partly, the hemicellulose of the wood, characterized in that it consists of monitoring, throughout the whole of the said stage, the existing quantity of at least one of the gases resulting from the decomposition of the hemicellulose, and of interrupting this treatment stage as soon as this quantity begins to reach an approximately constant value.
- Method according to Claim 1, characterized in that the said gas is acetic acid and/or carbon dioxide and/or carbon monoxide.
- Method according to one of the foregoing Claims, characterized in that the said quantities of gas are detected by means of a sensor that is sensitive to at least one of the said gases and is situated in the treatment enclosure.
- Method according to Claim 1 or 2, characterized in that the quantity of the said gases is detected by means of a detector element constituted by a metal oxide.
- Method according to Claim 4, characterized in that the metal oxide is SnO2, TiO2 or ZnO.
- Method according to Claim 1 or 2, characterized in that the quantities of at least one of the said gases are detected by an analysis measurement chain by infra-red spectrography.
- Method according to Claim 1, characterized in that the wood is brought to and held at between 220°C and 300°C in an enclosure by heating, and in that the heating is stopped on detecting that the output signal of a sensor for at least one of the gases has reached an approximately constant value and possibly is starting to decrease.
- Method according to Claim 7, characterized in that the defined temperature in the enclosure is 230°C.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9609456A FR2751580B1 (en) | 1996-07-26 | 1996-07-26 | WOOD RETIFICATION PROCESS |
| FR9609456 | 1996-07-26 | ||
| PCT/FR1997/001396 WO1998004393A1 (en) | 1996-07-26 | 1997-07-25 | Wood curing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0854776A1 EP0854776A1 (en) | 1998-07-29 |
| EP0854776B1 true EP0854776B1 (en) | 2004-05-12 |
Family
ID=9494534
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP97935631A Expired - Lifetime EP0854776B1 (en) | 1996-07-26 | 1997-07-25 | Wood curing method |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5901463A (en) |
| EP (1) | EP0854776B1 (en) |
| JP (1) | JPH11512987A (en) |
| AT (1) | ATE266509T1 (en) |
| CA (1) | CA2232974C (en) |
| DE (1) | DE69729061D1 (en) |
| FR (1) | FR2751580B1 (en) |
| WO (1) | WO1998004393A1 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2781180B1 (en) | 1998-07-17 | 2000-09-29 | Fours Et Bruleurs Rey | WOOD RETIFICATION REACTOR |
| FR2804629A1 (en) * | 2000-01-21 | 2001-08-10 | D Abadie Humberto Roque Carril | Procedure for converting cottonwood into high grade wood, comprises controlled stages of felling, cutting, release of water and resin,drying, immersion, release of impurities, modeling and surfacing |
| BR0006399B1 (en) | 2000-12-20 | 2010-06-15 | accelerated wood drying process based on its rheological properties. | |
| US7537619B2 (en) | 2004-04-08 | 2009-05-26 | Félix Huard Inc. | Method and system for the treatment of betula wood |
| FR2871181B1 (en) | 2004-06-02 | 2006-09-08 | Epmb H Soc Par Actions Simplif | MODULAR CONSTRUCTION SYSTEM |
| US7963048B2 (en) * | 2005-05-23 | 2011-06-21 | Pollard Levi A | Dual path kiln |
| US8201501B2 (en) | 2009-09-04 | 2012-06-19 | Tinsley Douglas M | Dual path kiln improvement |
| DE102009047137A1 (en) | 2009-11-25 | 2011-05-26 | Institut Für Holztechnologie Dresden Gemeinnützige Gmbh | Method for thermal modification or remuneration of wood and wood products in thermal chambers, involves placing wood or wood product between gas tight, temperature and corrosion-resistant and goods heat conducting cover plate |
| JP5843394B2 (en) * | 2012-02-29 | 2016-01-13 | 第一高周波工業株式会社 | Method and apparatus for processing lignocellulosic material |
| US10619921B2 (en) | 2018-01-29 | 2020-04-14 | Norev Dpk, Llc | Dual path kiln and method of operating a dual path kiln to continuously dry lumber |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2916677A1 (en) * | 1979-04-25 | 1980-11-06 | Ruetgerswerke Ag | METHOD FOR RETURNING WOOD |
| FR2604942B1 (en) * | 1986-10-10 | 1988-12-23 | Armines | PROCESS FOR MANUFACTURING LIGNOCELLULOSIC MATERIAL BY HEAT TREATMENT AND MATERIAL OBTAINED BY THIS PROCESS |
| US5169687A (en) * | 1988-09-16 | 1992-12-08 | University Of South Florida | Supercritical fluid-aided treatment of porous materials |
| JPH03111749A (en) * | 1989-09-26 | 1991-05-13 | Mitsui Petrochem Ind Ltd | Carbon-dioxide-gas detecting material |
| ES2091087T3 (en) * | 1993-04-29 | 1996-10-16 | Shell Int Research | PROCEDURE TO IMPROVE THE QUALITY OF LOW QUALITY WOOD. |
| FR2720969A1 (en) * | 1994-06-14 | 1995-12-15 | Herve Montornes | Treatment of green wood |
-
1996
- 1996-07-26 FR FR9609456A patent/FR2751580B1/en not_active Expired - Fee Related
-
1997
- 1997-07-25 CA CA002232974A patent/CA2232974C/en not_active Expired - Fee Related
- 1997-07-25 AT AT97935631T patent/ATE266509T1/en not_active IP Right Cessation
- 1997-07-25 JP JP10508558A patent/JPH11512987A/en active Pending
- 1997-07-25 US US09/043,474 patent/US5901463A/en not_active Expired - Fee Related
- 1997-07-25 WO PCT/FR1997/001396 patent/WO1998004393A1/en active IP Right Grant
- 1997-07-25 DE DE69729061T patent/DE69729061D1/en not_active Expired - Lifetime
- 1997-07-25 EP EP97935631A patent/EP0854776B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2232974A1 (en) | 1998-02-05 |
| WO1998004393A1 (en) | 1998-02-05 |
| CA2232974C (en) | 2006-01-24 |
| FR2751580A1 (en) | 1998-01-30 |
| US5901463A (en) | 1999-05-11 |
| FR2751580B1 (en) | 1998-10-16 |
| JPH11512987A (en) | 1999-11-09 |
| ATE266509T1 (en) | 2004-05-15 |
| DE69729061D1 (en) | 2004-06-17 |
| EP0854776A1 (en) | 1998-07-29 |
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