EP0730130B1 - Procédé et dispositif de séchage du bois - Google Patents

Procédé et dispositif de séchage du bois

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Publication number
EP0730130B1
EP0730130B1 EP19950810134 EP95810134A EP0730130B1 EP 0730130 B1 EP0730130 B1 EP 0730130B1 EP 19950810134 EP19950810134 EP 19950810134 EP 95810134 A EP95810134 A EP 95810134A EP 0730130 B1 EP0730130 B1 EP 0730130B1
Authority
EP
European Patent Office
Prior art keywords
drying
chamber
wood
temperature
heat
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19950810134
Other languages
German (de)
English (en)
Other versions
EP0730130A1 (fr
Inventor
Jiro Sato
Naoya Nara
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Individual
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Individual
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Filing date
Publication date
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Priority to DE1995602692 priority Critical patent/DE69502692T2/de
Priority to EP19950810134 priority patent/EP0730130B1/fr
Publication of EP0730130A1 publication Critical patent/EP0730130A1/fr
Application granted granted Critical
Publication of EP0730130B1 publication Critical patent/EP0730130B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B9/00—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards
    • F26B9/06—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B2210/00—Drying processes and machines for solid objects characterised by the specific requirements of the drying good
    • F26B2210/16—Wood, e.g. lumber, timber

Definitions

  • the present invention relates to a process and equipment for drying wood and, more particularly, to a process for holding raw wood such as sawn wood including logs, timbers and lumber, and boards in a drying chamber, in which they will be artificially dried by increasing a drying chamber temperature to a specific degree.
  • the target percentage of moisture content is not uniformized, and no complete drying that largely affects various strengths of wood can be expected. Also, because drying starts at the surface layer side where moisture evaporates, a crack occurs in the surface layer with the unisotropy of shrinkage caused by drying, resulting in substantial deterioration of utility value due to a large decrease of a material usable for building and fittings, or in a large increase in a useless material. According to the prior art drying technology, therefore, it is impossible to perform wood drying without cracking, especially to dry logs and lumber having a core.
  • Logs and lumber having a heart are, from their nature, liable to crack from the surface layer towards the central layer in an artificial drying process.
  • wood shrinkage in each direction caused by drying is greater in a radial direction advancing from the surface layer towards the central layer than in a circumferential direction (a tangential direction relative to annual rings) along the surface layer; and therefore if the surface layer is dried earlier than the central layer side, the wood is liable to crack in the surface layer containing much moisture where coarse annual rings are formed as compared with those on the central layer side, and a crack tends to gradually advance radially towards the central layer.
  • the present invention which has as an object the provision of an epoch-making process and equipment capable of completely drying at a lower cost the whole part of wood from the surface layer to the central layer without cracking.
  • a technical means pertaining to the present invention presents a drying process which includes a primary drying process that many pieces of wood stacked in multiple stages at spacings are held in a drying chamber equipped with an exhaust system for maintaining a chamber pressure at a normal pressure or in a state close thereto so that heat may pass among the pieces of wood, and then only live steam is fed into the drying chamber to heat the chamber interior from the normal temperature up to 90 to 100°C, thereby heating the whole interior ranging from the surface layer to the central layer of the wood; a secondary drying process that, after the central layer of the wood is heated up to 90 to 100°C, the chamber interior is heated up to the temperature of 100 to 200°C by the use of a heater, thereby boiling the moisture content in the wood for the purpose of high-temperature treatment up to a fiber saturation point in order to obtain a target percentage of moisture content; and a tertiary drying process that, when the moisture content has dropped to the fiber saturation point, drying chamber temperature conditions such as the dry-bulb temperature and
  • the present invention provides a drying process that at a point of time of the drying treatment of wood to the target percentage of moisture content by the tertiary drying process, the chamber temperature condition of only the wet-bulb temperature is changed to remove a residual drying stress and moisture content inclination of wood under the condition.
  • a drying equipment disclosed in the present invention comprises a drying chamber of an approximately rectangular form as viewed in a plan view which has a wood entrance hermetically closed with a door on one side, and a boiler room disposed beside the drying chamber; in the upper part of the drying chamber are routed, from the boiler room, steam injection pipes for heating to raise the chamber temperature by supplying live steam into the chamber and a heater for heating to raise the chamber temperature by means of heat exchange; also in proper places inside the drying chamber are set an exhaust system for natural exhaust during heating to raise the chamber temperature to thereby maintain the chamber pressure at a normal value or close thereto, the steam injection pipes, and a circulating apparatus for circulating the heat from the heater to the entire area of the chamber interior during the heat-up; and furthermore on the floor of the drying chamber are laid rails for bringing in a truck loaded with multi-stage stacks of a number of timbers and for taking the truck out after the completion of drying.
  • the circulating apparatus of the drying equipment is provided with a propeller shaft horizontally supported on a heat-resisting bearing at the lower end of a supporting member suspended from the ceiling, with one end of the propeller shaft protruding out of the drying chamber through a through hole which has a heat-resisting sealing member at the edge and opens in the side wall of the chamber.
  • a motor is disposed outside of the side wall on the axial center of the shaft, being connected with one protruding end of the shaft, and is mounted with a propeller fan on the other end of the shaft in the drying chamber.
  • the drying equipment has an opening-closing damper disposed in an exhaust passage provided in a proper place in the drying chamber and so designed as to automatically exhaust unidirectionally by utilizing the internal pressure of the drying chamber.
  • the drying chamber is heated from the normal temperature up to 90 to 100°C with the live steam alone; with this condition maintained, the heat is supplied throughout the chamber interior to heat multi-stage stacks of wood arranged at spacings through which the heat passes.
  • the chamber humidity gradually rises with the rise of temperature, reaching 100% at a point of time when the temperature has reached 90 to 100°C.
  • the heat therefore, is gradually transmitted to the central layer of wood while the drying of the surface layer part of wood is being restrained by the atmosphere of the 100% humidity, thereby ensuring uniform and balanced heating of the entire inner part of the wood at temperatures near 90 to 100°C immediately before boiling of the moisture content while preventing the surface layer part of the wood from drying. That is, the primary drying is accomplished by the combination of balanced temperature and humidity for uniformized and balanced heating of the whole inner part of wood ranging from the surface layer to the central layer in accordance with a so-called drying schedule.
  • the chamber interior is quickly heated up to 100 to 200°C by the heater, and by maintaining this state, the inner part of the wood is rapidly heated up to 100 to 200°C to thereby boil the moisture content in the wood and at the same time an increased pressure is applied to let the boiled moisture out of both ends of the wood, thus accomplishing the secondary drying to the fiber saturation point.
  • the drying chamber pressure that has increased with the rise of the chamber temperature is discharged out of the drying chamber from by means of the exhaust system, thereby maintaining the chamber interior at the normal temperature or a temperature close thereto.
  • the boiled moisture in the wood is blown off quickly, thereby enabling to equalize the drying speed (a rate of decrease in the moisture content) between the surface layer side and the central layer side, or to bring the drying speeds on both the surface layer side and the central layer side as close to each other as possible in order to realize the uniform and balanced drying of the entire inner part of the wood.
  • the drying conditions such as the dry-bulb temperature and the wet-bulb temperature within the drying chamber are changed according to the drying conditions of the wood and, by keeping the drying conditions for a specific period of time, the moisture content in the inner part of the wood is dried to the target moisture content, to thereby accomplish the tertiary drying.
  • wood loaded in multiple stages on a truck on rails is brought into the drying chamber at the entrance with the door opened, and after the wood is unloaded in the drying chamber and the entrance door is closed, the boiler is operated to send live steam from the boiler room to the steam injection pipe routed in the upper part of the drying chamber.
  • the live steam is then injected into the drying chamber from above in the chamber to thereby heat the chamber interior from the normal temperature up to 90 to 100°C.
  • the live steam heat is uniformly applied by the circulating apparatus to the whole wood stacked in multiple stages at spacings on the truck through which the heat passes, thus heating up each piece of the wood.
  • the drying chamber temperature is raised gradually to 90 to 100°C with the live steam
  • the humidity also gradually increases with the rise of the chamber temperature, reaching 100%. Therefore, under the condition that the drying of the surface layer part of the wood is held in the atmosphere of the 100% humidity, the heat is gradually transmitted to the central layer until the wood is heated up uniformly and in a balanced manner throughout its inner part at the temperature of 90 to 100°C or a temperature close thereto immediately before the boiling of moisture. That is, the wood can be heated up uniformly and equally through the entire inner part ranging from the surface layer to the central layer according to a so-called drying schedule made for ensuring a balanced relationship between temperature and humidity by the use of a combination of temperature and humidity.
  • a hot steam is subsequently fed from the boiler room to the heater disposed in the upper part in the drying chamber, thereby heating up the chamber interior quickly to 100 to 200°C by heat radiated from the heater. Then, the wood inner part is rapidly heated up to 100 to 200°C, whereby the moisture in the wood quickly starts boiling, being blown off at both ends of the wood. Thus the wood is dried up to the fiber saturation point.
  • the boiled moisture in the wood is blown off quickly at both ends of the wood to thereby balance the drying speed (a rate of decrease in the percentage of moisture content) between the surface layer side and the central layer side, or to bring the drying speed on the central layer side as close to that on the surface layer side as possible in order to ensure uniformized and balanced drying of the whole inner part of the wood.
  • the drying conditions including the dry-bulb temperature and the wet-bulb temperature in the drying chamber are changed in accordance with the dried condition of the wood; the dried condition is then kept for a specific period of time until the completion of drying, thereby drying the wood to the target percentage of moisture content in the wood.
  • the motor is mounted outside to drive the proper fan in the drying chamber from outside, whereby the motor can be protected from the heat in the drying chamber where the drying temperature reaches 100°C or over.
  • the internal pressure in the drying chamber increases over the normal pressure when the drying chamber is heated up with the live steam emitted from the steam injection pipe disposed in the upper part of the drying chamber and the heat radiated from the heater, thus forcing the opening-closing damper of the exhaust passage to open.
  • the internal pressure of the drying chamber exceeding the normal pressure then goes through the exhaust passage for natural exhaust out of the drying chamber, thereby maintaining the condition to force the boiling moisture out from both ends of the wood, that is, the internal pressure of the drying chamber at the normal pressure or close thereto.
  • FIGs. 1 to 5 show one example of the drying equipment for performing the drying process (hereinafter referred to as the present process) for drying a raw log 1 with bark (hereinafter referred to only as the log);
  • A denotes a drying chamber which is constituted, in an approximately rectangular form in a plane, of a floor A-1, side walls A-2 and a ceiling A-3 by filling a heat-insulating material 2-3 between an external wall material 2-1 produced of a waved steel plate and an internal wall material 2-2 produced of a ceramic-coated (surface-treated) stainless plate.
  • the drying chamber is so constituted that many logs stacked in multiple stages in several horizontal rows at spacings through which the heat passes can be brought into the drying chamber by a truck 4 which travels on stainless rails 3 laid from the floor A-1 in the drying chamber towards the outside of the chamber through the entrance provided on one side thereof.
  • a truck 4 which travels on stainless rails 3 laid from the floor A-1 in the drying chamber towards the outside of the chamber through the entrance provided on one side thereof.
  • an exhaust system 5 On the side wall A-2 of the drying chamber A is installed an exhaust system 5 to prevent the chamber pressure from increasing with the rise of the chamber temperature. Natural exhaust through this exhaust system 5 keeps the pressure in the drying chamber A at the normal pressure or at a pressure close thereto.
  • the drying chamber A of the present embodiment comprises a lower unit A' and an upper unit A''; the lower unit A' being factory-built by integrally assembling the side walls A-2 rising from the periphery of the floor A-1 to the entire floor A-1 to a halfway height and the upper unit A'' being also factory-built by integrally assembling remaining side walls A-2 to the entire ceiling A-3.
  • the lower unit A' and the upper unit A'' thus built are carried to the site, where the upper edge of the side wall A-2 of the lower unit A' and the lower edge of the side wall A-2 of the upper unit A'' are connected by welding or other as shown in Fig. 3.
  • the exhaust system 5 functions to maintain the internal pressure of the drying chamber at the normal pressure or at a pressure close thereto by releasing by natural exhaust the pressure out of the drying chamber A when the internal pressure has exceeded the normal pressure with the heat-up of the interior of the drying chamber A.
  • an opening-closing damper 5-2 in an exhaust passage 5-1 which is open in the side wall A-2 of the drying chamber A; the damper 5-2 is pushed to automatically open only in a direction of exhaust with the internal pressure.
  • the opening-closing damper 5-2 is formed of a light-weight material so as to be opened with the internal pressure of the drying chamber A, and is axially supported at the upper edge to operably hang in the exhaust passage.
  • a seal frame 5-3 for stopping the damper from opening on the drying chamber A side is mounted on the peripheral wall of the exhaust passage 51 so that the damper will open only in the direction of exhaust. Furthermore, in the exhaust passage 5-1 of the exhaust system 5, an exhaust fan 6 is inserted and connected for forcing the damper 5-2 to open when the drying equipment of the present invention is used in low-temperature drying, thus discharging the internal pressure as shown in Fig. 7.
  • a reference numeral 7 refers to a drain hole provided in a form of passage in the floor A-1 of the drying chamber A, the passage being directed outwardly in order to rapidly discharge the moisture blown off of the log 1 outside without remaining on the floor A-1.
  • This drain hole 7 functions to discharge the moisture forced out of the log 1, to the outside of the chamber, also serving as an exhaust port for discharging the chamber pressure outside by natural exhaust in order to restrain the increase of the chamber pressure with the rise of the chamber temperature. That is, the drain hole 7 keeps the normal pressure or a pressure close thereto within the exhaust system 5 as well as the drying chamber A.
  • a heater 9 and a steam injection pipe 8 routed from the boiler room B beside the drying chamber A so that a primary drying will be performed by heating the chamber interior up to 90 to 100°C with live steam injected from the steam injection pipe 8, and subsequently a secondary drying will be performed by heating the chamber interior up to 100 to 200°C quickly with the heat supplied from the heater 9, thereby drying the logs 1 containing 140% moisture up to the 25 to 28% fiber saturation point at which the moisture content of the logs 1 reaches the target value of 17%.
  • the boiler used in the present embodiment has a maximum capacity to increase the chamber temperature up to the saturation temperature of about 164 to 170°C at the normal pressure of 7 to 8 kg/cm 2 and up to the saturation temperature of about 204°C at the normal pressure of 16 kg/cm 2 .
  • a plurality of injection pipes 8 are installed on the right and left sides in the vicinity of the ceiling A-3 of the drying chamber A, for injecting the live steam from the boiler room B into the drying chamber at the injection port to thereby heat up the chamber interior from the normal temperature to 90 to 100°C.
  • the heater 9 is a heat exchanger for heating the drying chamber A by heat exchange with the heating pipes 9-1 having a number of fins and routed in a vertical parallel form on the right and left on the ceiling A-3 of the drying chamber A. Steam is passed through each of the heating pipes 9-1 to exchange heat with the interior of the drying chamber A, thereby heating the drying chamber A interior up to 100 to 200°C with the live steam injected from the steam injection pipe 8.
  • the circulating apparatus 10 is of such a constitution that a propeller shaft 10-1 is axially supported horizontally on the lower end of a supporting member 11 hanging from the ceiling A-3, through a heat-resisting bearing 12, with its one end protruding out of the drying chamber A through a through hole 13 provided in the side wall A-2, and that a motor 10-2 is mounted outside of the side wall A-2 on the axial center of the propeller shaft 10-1; the motor 10 being directly coupled with the protruding one end of the shaft 10-1 by means of a coupling 14. Then, a propeller fan 10-3 is mounted on the other end of the propeller shaft 10-1 disposed in the drying chamber A.
  • the propeller shaft 10-1 is produced of a heat-resisting stainless steel, with its one end side protruding out from the through hole provided in the side wall A-2 and with the other end side being axially supported through a heat-resisting bearing 12 to the lower end of the supporting member 11 suspended from the ceiling A-3 between both steam injection pipes 8 and the heater 9; the one end side protruded outside is axially supported on a bearing 16 mounted on a base 15 on which the motor 10-2 is mounted, whereby one end side of the propeller shaft protruding outside is directly coupled by the coupling 14 to the motor 10-2, while the other end disposed between the steam injection pipes 8 arranged on both sides in the upper part of the drying chamber A and the heater 9 is mounted with a propeller fan 10-3.
  • the through hole 13 in which a stainless steel pipe is inserted to support the propeller shaft 10-1 protruding out of the drying chamber A is fitted with a heat-resisting seal member 17 on the outside open end thereof, thereby preventing the outflow (discharge) of the heat from inside the drying chamber.
  • the heat-resisting bearing 12 is composed of a stainless steel bearing case, a shaft supporting case, and ceramic balls interposed between these cases, and is so designed as to smoothly support the propeller shaft 10-1 without being affected by the heat of the chamber interior.
  • the motor 10-2 of the circulating apparatus for driving the propeller fan 10-2 through the propeller shaft 10-1, being disposed outside of the drying chamber, is designed to be free from the direct effect of the chamber heat exceeding 100°C. That is, the motor liable to a thermal effect is protected from the chamber heat, thus enabling to extend its lifetime.
  • the live steam is supplied from the boiler room B into the steam injection pipes 8 arranged in the upper part of the drying chamber A.
  • the live steam alone is then injected from the steam injection pipes 8 to heat the drying chamber A up to a temperature of 90 to 100°C, so that 90 to 100°C heat is uniformly circulated by the circulating apparatus 10 throughout the chamber interior to heat up the logs 1 which are stacked in multiple stages at spacings on square lumbers 18 used as spacer blocks, through which the heat passes, with a weight 19 placed on the uppermost stage of the logs 1 brought by the truck 4 into the drying chamber A for the purpose of warp prevention of the logs 1 during drying, thus accomplishing the primary drying.
  • the steam is supplied from the boiler room B to the heater 9 located in the upper part of the drying chamber A to heat the chamber interior rapidly up to 100 to 200°C by heat exchange with the heat radiated from the heating pipe 9-1 of the heater 9, thus heating up the logs 1 quickly for the purpose of high-temperature treatment at 100 to 200°C as the secondary drying process in which the logs 1 containing 140% moisture for example are dried to the target percentage of moisture content of 17% without cracking which is a vital problem of log drying.
  • the logs 1 have been dried to the target percentage of moisture content of 17%, only the wet-bulb temperature of the temperature conditions in the chamber is changed to remove a residual drying stress and moisture inclination of the wood under the temperature conditions.
  • the chamber temperature is held within the range of from 90°C to 100°C in the primary drying.
  • the chamber temperature is held within the range of from 100°C to 200°C.
  • the moisture in the logs 1 when the drying temperature is quickly raised to 100 to 200°C, the moisture in the logs 1 must also quickly begin to boil almost simultaneously for rapid drying of the log inner part; if not, the surface layer part of the logs 1 which has a higher moisture content and is more liable to crack than the central layer side begins to dry first with the high-temperature heat of 100 to 200°C, producing a radial crack which starts in the surface layer part, developing towards the central layer.
  • moisture evaporation from the surface layer part of the logs 1 will advance first, to thereby dry the surface layer part before the moisture boiling in the inner part begins, thus allowing occurrence of a crack in the surface layer part owing to circumferential shrinkage of the logs 1.
  • the drying temperature in the primary drying is set to the range of from 90 to 100°C.
  • the drying temperature in the drying chamber A is 100°C or lower, there will take place the same trouble as in the case of the primary drying where the drying temperature exceeds 100°C; that is, quick moisture boiling in and expelling from the inner part of the logs 1 can not be expected.
  • the drying temperature is set to the range of from 100 to 200°C, whereby the inner part of the logs 1 that has been heated, in the primary drying, to a point immediately before the boiling of moisture may quickly be heated up, so that the moisture may quickly be blown off for rapid drying of the inner part before the drying of the surface layer part advances. That is, it becomes possible to form the most desirable drying conditions (the drying atmosphere) in the drying chamber A in which the surface layer side and the central layer side of the logs 1 can be dried at an equal drying speed (a rate of decrease in the percentage of moisture content), or the drying speeds at these sides can be brought as close to each other as possible.
  • a number of logs 1 are loaded in multiple stages on several trucks 4, with a spacing provided by interposing space blocks 16 between the logs 1 through which the heat passes, and are brought into the drying chamber 4. Then, with the door A-4 and an inspection door A-5 closed, the live steam is sent from the steam injection pipes 8 into the drying chamber 4, to thereby heat the drying chamber A interior up to 90 to 100°C. From a point of time when the chamber temperature has reached this temperature range, the primary drying was carried out while holding the temperature for a period of six to eight hours.
  • the steam circulating apparatus 10 is started to send the live steam to the whole chamber interior until the heat reaches all of the logs 1 stacked at spacings through which the heat flows to heat up the logs 1.
  • the humidity in the chamber interior gradually rises to 100% with the rise of the chamber temperature; the drying of the surface layer part of the logs is held by the atmosphere of the 100% humidity and in this state the heat is gradually transmitted to the central layer of the logs 1.
  • the logs 1 are heated uniformly and equally up to 90 to 100°C or to a temperature close thereto immediately before the moisture in the entire inner part begins to boil.
  • the heat is circulated by the circulating apparatus 10 throughout the chamber interior.
  • the chamber temperature is quickly raised by the heater 9 from the temperature of 90 to 100°C up to the temperature of 100 to 200°C.
  • the secondary drying is performed at the chamber temperature of 100 to 200°C kept for about 24 hours.
  • the opening-closing damper 5-3 of the exhaust system 5 is automatically opened to allow the internal pressure of the drying chamber A out through the exhaust passage 5-1, and therefore the chamber interior is constantly kept at the normal pressure or a pressure close thereto; the boiling moisture in the inner part of the log 1 is forced to be quickly blown off from both ends of the log 1, so that the surface layer side and the central layer side will be dried at an equal drying speed (a rate of decrease in the percentage of moisture content), or the drying speeds on both sides will be as close to each other as possible, thereby enabling uniform and equalized drying of the entire inner part of the log 1 without a crack while lowering the moisture content in the inner part of the log 1.
  • the dry-bulb temperature in the chamber is changed to 70°C and the wet-bulb temperature to 68°C (relative humidity, approximately 91%) according to the dried condition of the logs 1. Then, after this condition is held for about one day, only the wet-bulb temperature is further changed to 66°C (relative humidity, approximately 83%), which is held for about one day to accomplish the tertiary drying. In this case, the humidity also is gradually lowered with the lowering of the chamber temperature, to enable to dry the inner part of the logs 1 to the target moisture content of 17% without cracking.
  • the wet-bulb temperature alone is changed to the drying condition of 69°C (relative humidity, approximately 96%) as a process for removing the residual drying stress and moisture inclination (a difference in the moisture content between the surface layer and the central layer) of the dried logs 1.
  • the door A-4 is opened to bring the logs 1 out of the drying chamber A.
  • wood to be dried includes conifers such as Japanese larch, spruce, red pine, etc. and broad-leaved trees such as oak, Japanese judas tree, shioji, etc. but is not limited thereto; that is, the wood to be dried by the present invention is wood to be used for structures (building materials), fixtures, and furniture.
  • the drying process and equipment of the present invention having the above-described constitution, have the following effect of operation.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)

Claims (5)

  1. Procédé de séchage du bois, comprenant un séchage primaire dans lequel de nombreux morceaux de bois entassés sur de multiples étages espacés sont maintenus dans une chambre de séchage équipée d'un système d'échappement pour maintenir une pression atmosphérique ou un état proche de celle-ci, de sorte que la chaleur puisse passer parmi les morceaux dudit bois, et seulement alors ladite chambre de séchage est alimentée en vapeur vive pour chauffer un intérieur de chambre d'une température ambiante jusqu'à 90 à 100°C, en chauffant ainsi tout l'intérieur allant depuis une couche de surface jusqu'à une couche centrale dudit bois; un séchage secondaire dans lequel, après que ladite couche centrale dudit bois a été chauffée jusqu'à 90 à 100°C, ledit intérieur de chambre est chauffé jusqu'à une température de 100 à 200°C à l'aide d'un élément chauffant, en évaporant ainsi l'humidité dans ledit bois jusqu'à un point de saturation des fibres, en vue d'un traitement à haute température, afin d'obtenir un pourcentage cible de teneur en humidité; et un séchage tertiaire dans lequel, lorsque la teneur en humidité est tombée jusqu'audit point de saturation des fibres, les conditions de température de la chambre de séchage telles que la température au thermomètre sec et la température au thermomètre mouillé sont modifiées pour traiter ledit bois dans lesdites conditions de température, à basses températures et faible humidité, jusqu'audit pourcentage cible de teneur en humidité.
  2. Procédé de séchage du bois selon la revendication 1, dans lequel uniquement la température au thermomètre mouillé desdites conditions de température est modifiée à un moment dans le temps lorsque ledit bois a été séché jusqu'audit pourcentage cible de teneur en humidité, en effectuant ainsi le traitement de séchage pour éliminer une tension de séchage résiduelle et une tendance à l'humidité résiduelle dudit bois.
  3. Dispositif de séchage du bois, comprenant une chambre de séchage de forme approximativement rectangulaire vue en plan, qui présente, d'un côté, une entrée pour le bois fermée hermétiquement avec une porte, et une salle de chaudière disposée à côté de ladite chambre de séchage; dans la partie supérieure de ladite chambre de séchage étant acheminés, depuis ladite salle de chaudière, des tuyaux d'injection de vapeur pour chauffer une chambre en alimentant ladite chambre en vapeur vive et un élément chauffant étant prévu pour augmenter la température de la chambre au moyen d'un échange de chaleur; également, dans des emplacements appropriés à l'intérieur de ladite chambre de séchage étant installés un système d'échappement pour les gaz d'échappement naturels au cours de l'élévation de la température de la chambre pour maintenir ainsi la pression de la chambre à une valeur atmosphérique ou proche de celle-ci, lesdits tuyaux d'injection de vapeur, et un appareil de circulation pour faire circuler la chaleur depuis ledit élément chauffant jusqu'à la zone toute entière dudit intérieur de chambre au cours de l'élévation de température; et en outre, sur le sol de ladite chambre de séchage des rails étant posés pour amener, dans un chariot à plusieurs étages chargé de piles d'un certain nombre de pièces de bois et pour ressortir ledit chariot après la fin du séchage.
  4. Dispositif de séchage du bois selon la revendication 3, dans lequel ledit appareil de circulation est pourvu d'un arbre de transmission supporté horizontalement sur un palier résistant à la chaleur à l'extrémité inférieure d'un organe de support suspendu depuis un plafond, une extrémité dudit arbre de transmission faisant saillie hors de ladite chambre de séchage par un trou traversant qui présente au bord un organe d'étanchéité résistant à la chaleur et débouche dans une paroi latérale de ladite chambre; et dans lequel un moteur est disposé en dehors de ladite paroi latérale sur le centre axial dudit arbre, connecté à une extrémité en saillie dudit arbre, et est monté avec une soufflerie à hélice sur l'autre extrémité dudit arbre dans ladite chambre de séchage.
  5. Dispositif de séchage du bois selon la revendication 3, dans lequel ledit système d'échappement présente un modérateur de fermeture-ouverture disposé dans un passage d'échappement prévu dans un emplacement approprié dans ladite chambre de séchage et est conçu pour réaliser un échappement automatique dans une direction unique en utilisant la pression interne de ladite chambre de séchage.
EP19950810134 1995-03-02 1995-03-02 Procédé et dispositif de séchage du bois Expired - Lifetime EP0730130B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE1995602692 DE69502692T2 (de) 1995-03-02 1995-03-02 Verfahren und Vorrichtung zum Trocknen von Holz
EP19950810134 EP0730130B1 (fr) 1995-03-02 1995-03-02 Procédé et dispositif de séchage du bois

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Application Number Priority Date Filing Date Title
EP19950810134 EP0730130B1 (fr) 1995-03-02 1995-03-02 Procédé et dispositif de séchage du bois

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EP0730130A1 EP0730130A1 (fr) 1996-09-04
EP0730130B1 true EP0730130B1 (fr) 1998-05-27

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DE (1) DE69502692T2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT410069B (de) * 2000-11-02 2003-01-27 Muehlboeck Kurt Verfahren zur hochtemperaturbehandlung von holz
CN101655307A (zh) * 2009-09-22 2010-02-24 北京林业大学 一种太阳能预干-除湿-常规多段组合木材干燥方法
CN106288682A (zh) * 2016-08-19 2017-01-04 周毅 腐竹低温烘干箱

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FR2781180B1 (fr) * 1998-07-17 2000-09-29 Fours Et Bruleurs Rey Reacteur de retification du bois
FR2790698B1 (fr) * 1999-03-09 2001-07-06 Jean Laurencot Dispositif pour le traitement thermique a haute temperature d'une matiere ligneuse
AT410070B (de) * 2000-11-02 2003-01-27 Muehlboeck Kurt Verfahren und vorrichtung zur hochtemperaturbehandlung von holz
ITVI20010032A1 (it) * 2001-02-06 2002-08-06 Antonio Salviati Sistema per essiccare materiali preformati nell'industria delle ceramiche dei laterizi delle paste alimentari del legno dei pellami e mezzi
FR2856330B1 (fr) * 2003-06-17 2005-09-02 Perrachon Et Fils Procede de vieillissement du chene
US8397400B2 (en) * 2010-05-25 2013-03-19 Forest Research Institute Malaysia High temperature lumber treatment system
EP2972033B1 (fr) 2013-03-15 2019-07-24 Usnr, Llc Séchoirs de bois débité multivoie unidirectionnels
AU2014237510B2 (en) 2013-03-15 2017-06-29 Usnr, Llc Multi-pass lumber kilns
CN105716373A (zh) * 2016-01-30 2016-06-29 安徽福沃德干燥设备有限公司 杨木在干燥窑内的干燥方法及其使用的干燥窑
CN108955112B (zh) * 2018-07-09 2020-08-18 内蒙古农业大学 模块组合型木材干燥器

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US1725708A (en) * 1924-08-22 1929-08-20 Elihu W Fowler Process and machine for drying lumber
FR1023606A (fr) * 1949-08-18 1953-03-20 Procédé pour le séchage des bois et analogues par la vapeur surchauffée
GB845751A (en) * 1956-03-02 1960-08-24 John Hamilton Stubber Improvements in or relating to the seasoning of timber
US3131034A (en) * 1961-03-02 1964-04-28 Marsh Julius Everett Process for drying lumber
FR1315881A (fr) * 1961-12-08 1963-01-25 Perfectionnements aux groupes de conditionnement d'air des séchoirs à bois
US3971139A (en) * 1973-09-14 1976-07-27 Rochon Marcel A Process and apparatus for decreasing moisture content in wood
US4182048A (en) * 1978-02-21 1980-01-08 U.S. Natural Resources, Inc. Method of drying lumber
FR2604245B1 (fr) * 1986-09-19 1988-12-23 Gautreau Jean Paul Procede de sechage de produits hygroscopiques de fortes epaisseurs, notamment du bois.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT410069B (de) * 2000-11-02 2003-01-27 Muehlboeck Kurt Verfahren zur hochtemperaturbehandlung von holz
CN101655307A (zh) * 2009-09-22 2010-02-24 北京林业大学 一种太阳能预干-除湿-常规多段组合木材干燥方法
CN106288682A (zh) * 2016-08-19 2017-01-04 周毅 腐竹低温烘干箱

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DE69502692T2 (de) 1999-02-25
DE69502692D1 (de) 1998-07-02

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