Abstract:
An apparatus for thermo-transformation of wood planks comprises a chamber delimited by upright perforated walls, a top wall and end walls and having a closable entry for receiving wood planks into the chamber. A shell surrounds the chamber and is spaced therefrom to define a first vertical plenum with the first perforated wall, a second vertical plenum with the second perforated wall, and a horizontal plenum with the top wall. A ventilation system is in fluid communication with the plenums to produce a flow of heated air in the plenums. Vanes are actuatable to close/open access to the vertical plenums, to allow heated air into at least one of the vertical plenums, through the chamber via the perforated walls, and out from at least the other of the vertical plenums, to return to the ventilation system. A method for the thermo-transformation of wood is also provided.

Description:
FIELD OF THE APPLICATION 
       [0001]    The present disclosure pertains to the thermo-transformation of wood, also referred to as torrefaction, and to equipment and a method used for the thermo-transformation of wood. 
       BACKGROUND OF THE ART 
       [0002]    The process of wood torrefaction or thermo-transformation removes a major portion of the internal moisture of wood, rendering the torrefied wood resistant to bio-degradation, insect damage, and rotting. Torrefied wood will not shrink, swell or warp with changing weather and moisture conditions. Accordingly, torrefied wood is a durable material and is hence well suited for outdoor applications, among numerous possible uses. 
         [0003]    Moreover, as no chemicals are used in the torrefaction of wood, the wood keeps a natural appearance. In torrefying wood, the wood is subjected to high temperatures in an oven. However, one of the issues is the non-uniform coloring of the wood due to the torrefying process. Because of some variations in conditions in the torrefying oven, some planks may come out with different colors than other planks. Therefore, it is desirable to provide a thermo-transformation apparatus, system and/or method that perform generally uniform torrefying conditions. 
       SUMMARY OF THE APPLICATION 
       [0004]    It is therefore an aim of the present disclosure to provide an apparatus and system for the thermo-transformation of wood, that addresses issues associated with the prior art. 
         [0005]    Therefore, in accordance with the present application, there is provided an apparatus for thermo-transformation of wood planks, comprising: a chamber delimited by a first upright perforated wall, a second upright perforated wall, a top wall and end walls and having a closable entry for receiving wood planks into the chamber; a shell surrounding the chamber and spaced therefrom to define a first vertical plenum with the first perforated wall, and a second vertical plenum with the second perforated wall, and a horizontal plenum with the top wall; a ventilation system in fluid communication with the plenums to produce a flow of heated air in the plenums; and vanes in the plenums being actuatable to close/open access to the vertical plenums, to allow heated air into at least one of the vertical plenums, through the chamber via the perforated walls, and out from at least the other of the vertical plenums, to return to the ventilation system. 
         [0006]    Further in accordance with the present application, there is provided a method for performing a thermo-transformation treatment on wood planks, comprising: heating air and directing the heated air to a first vertical plenum; directing the heated air from the first vertical plenum transversely through a bundle of spaced-apart planks oriented lengthwise by way of a first perforated wall; and collecting the heated air in a second vertical plenum and directing the collected air to be reheated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a front sectional view of an apparatus for the thermo-transformation of wood in accordance with an embodiment of the present disclosure; 
           [0008]      FIG. 2  is a perspective view of an expandable shell of the apparatus of  FIG. 1 ; 
           [0009]      FIG. 3  is a top plan section view of the apparatus of  FIG. 1 ; 
           [0010]      FIG. 4  is a longitudinal sectional view of the apparatus of  FIG. 1 ; 
           [0011]      FIG. 5  is a top plan view of the apparatus of  FIG. 1 , showing ventilation units; 
           [0012]      FIG. 6  is a schematic view of a separator basin and burner used with the apparatus of  FIG. 1 ; 
           [0013]      FIG. 7  is a perspective view of a perforated panel of the separator basin of  FIG. 6 ; 
           [0014]      FIG. 8  is a schematic view of an exhaust recuperation unit as used with the apparatus of  FIG. 1 ; and 
           [0015]      FIG. 9  is a longitudinal sectional view of a cooling apparatus as used with the thermo-transformation apparatus of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Referring to the drawings and more particularly to  FIG. 1 , there is illustrated an apparatus for the thermo-transformation of wood. The thermo-transformation process is also referred to as torrefaction of wood. 
         [0017]    The apparatus  10  has a structural casing  12  in which the thermo-transformation process takes place. The structural casing  12  therefore has a door  13  to access an interior thereof. The configuration of the structural casing  12  is designed so as to maintain relatively stable conditions in an interior thereof and will be described in further detail hereinafter. 
         [0018]    Referring to  FIGS. 1 and 3  concurrently, perforated walls  14  are generally upstanding in an interior of the apparatus  10 . A top wall  16  is positioned atop the perforated walls  14  so as to define a thermo-transformation chamber  18  in which wooden planks are inserted and accommodated during the thermo-transformation process. 
         [0019]    It is observed that the perforated walls  14  are spaced apart from the structural casing  12 , thereby defining vertical plenums  20 A and  20 B. The perforated walls  14  are upright, namely they are generally vertical (more or less 90 degrees from the ground, with variations possible). The vertical plenums  20 A and  20 B extend the full length of the apparatus  10  and are on both sides of the thermo-transformation chamber  18 . As seen in  FIG. 1 , a horizontal plenum  22  is defined between the structural casing  12  and the top wall  16 . Accordingly, air may circulate between the horizontal plenum  22  and the vertical plenums  20 A and  20 B. 
         [0020]    Vanes  24 A and  24 B are respectively positioned at the junction between the vertical plenums  20 A and  20 B and the horizontal plenum  22 . The vanes  24 A and  24 B are automatically actuated so as to control an amount of air that passes from the horizontal plenum  22  to the vertical plenums  20 A and  20 B. Referring to  FIG. 3 , partition walls  25  are located in the horizontal plenum  22  to segment the horizontal plenum  22  in two subsections, namely subsections I-A and I-B in  FIG. 3 . Each of the subsections I-A and I-B has its own set of vanes  24 A and  24 B (or multiple vanes  24 A and  24 B). The partition walls  25  lie in a plane this is normal to a longitudinal dimension of the casing  12 . 
         [0021]    Referring to  FIG. 1 , baffle plates  26  are within the vertical plenums  20 A and  20 B. The baffle plates  26  are arranged so as to cause a generally uniform amount of air to pass through the openings in the perforated walls  14 . The perforated walls  14  have throttle disks  27  for each of their openings. The throttle disks  27  are adjustable manually to increase or lessen the entry of the openings, prior to the use of the apparatus  10 . 
         [0022]    As observed from  FIG. 3 , the horizontal plenum  22  is accessed via an inlet  28  and an outlet  29 . The inlet  28  receives heated air while the outlet  29  is for the exhaust of the air after it has circulated through a plank bundle, as part of the thermo-transformation process. Accordingly, ventilation units  30  are provided and positioned between the inlet  28  and the outlet  29  to cause a convection flow of the air within the thermo-transformation chamber  18 . 
         [0023]    Referring to  FIGS. 1 ,  4  and  5 , the ventilation units  30  are shown as having a fan  32 . A suction duct  34  relates the outlet  29  to the fan  32  while a feed duct  36  relates the fan  32  to the inlet  28 . A heating element  38  is within either one of the suction duct  34  and feed duct  36  but preferably after the fan  32 . Moreover, humidifying nozzles  40  may be provided to adjust the humidity level in the air that is being fed to the thermo-transformation chamber  18 . 
         [0024]    The thermo-transformation chamber  18  has an elongated shape to receive bundles of planks lengthwise. The elongated shape is particularly important in ensuring generally uniform torrefaction conditions. In an embodiment, the thermo-transformation chamber is at least 5′0″ large, for a 7′0″ height and 22′0″ length (effective dimensions). Therefore, the length to width ratio is high (at least 4.0), as opposed to existing torrefaction equipment. 
         [0025]    Now that the apparatus  10  has been structurally described, the thermo-transformation of wood therein is now set forth. Planks are mounted on trolley  42  (i.e., buggy, carriage, etc.) as shown in  FIG. 1 . The trolley  42  may be mounted on rails  44  extending from an exterior to an interior of the thermo-transformation chamber  18 . The planks are mounted onto the trolley  42  so as to be spaced apart from one another and therefore have all surfaces exposed during the thermo-transformation process. The planks of the bundle are arranged so as to be oriented lengthwise in chamber  18 . Provided the chamber  18  has an appropriate length, bundles may be put end to end. The length-to-width ratio of the chamber  18  is well suited for receiving the planks lengthwise. The planks are separated from one another by spacers, such that air may circulate between planks. 
         [0026]    It is observed from  FIG. 3  that the thermo-transformation apparatus  10  is separated in two sections by separator wall  46 . A first section I is a mirror image of second section II. For simplicity purposes, the flow of air in a single one of the sections I and II will be described, but the operation of the thermo-transformation process is similar for the sections I and II. 
         [0027]    The vane  24 A of subsection I-A of the partition walls  25  is opened while the vane  24 B of the subsection I-A are closed. Simultaneously, the vane  24 B of the subsection I-B (i.e., the side of the partition wall  25  incorporating the outlet  29 ) is opened while the vane  24 A of the subsection I-B is closed. Therefore, with this arrangement of closed and opened vanes  24 A and  24 B, the hot and humidified air entering via the inlet  28  will be directed into the vertical plenum  20 A of subsection I-A. This treatment air will be directed to the thermo-transformation chamber  18  by the baffle plates  26  and throttle disks  27  in such a way that the air will be generally uniformly distributed along the perforated walls  14  such that a generally equivalent amount of treatment air with generally uniform conditions reaches all foreground planks. The flow of air is thus generally perpendicular to the length of the planks in the bundles, by the arrangement of perforated walls  14  in the vertical plenums  20 A and  20 B. 
         [0028]    A vacuuming effect will induce a flow of the treatment air through the planks and to the vertical plenum  20 B of the subsection I-B. The treatment air will then be exhausted by the ventilation unit  30  to then be reheated and rehumidified. Therefore, a loop of treatment air is induced. 
         [0029]    After a predetermined amount of time, the vanes are reversed such that treatment air reaching the horizontal plenum  22  of the subsection I-A will firstly pass through the vertical plenum  20 B of the subsection I-A, to then exit via the vertical plenum  20 A of subsection I-B. Again, the flow of air will be generally perpendicular to the length of the planks in the bundles. The air will subsequently be exhausted via the outlet  29  to be treated by the ventilation unit  30 . 
         [0030]    Accordingly, the conditions to which all planks in the thermo-transformation chamber  18  will be subjected to are generally uniform. As mentioned previously, a similar air flow is induced in the section II of the apparatus  10 . 
         [0031]    The operation of the vanes to control the air flow in the chamber  18  may be performed as a function of parameters monitored throughout the thermo-transformation. For instance, as shown in  FIG. 1 , probes  48  (e.g., thermocouples, manometers, etc.). The parameters are collected by a processing unit or like controller means that will provide information required to control the vanes, and control the actuation of the vanes. 
         [0032]    Referring to  FIGS. 2 and 3 , an expandable shell  50  of the structural casing  12  is illustrated. The expandable shell  50  is designed to expand as a function of the temperature in the chamber  18 , in order to maintain relatively stable conditions therein. The expandable shell  50  consists of wall segments  51  interconnected by flanges  52  to form an accordion-like casing. The flanges  52  are longitudinally distributed on the shell  50 . 
         [0033]    As seen in  FIGS. 2 and 3 , the flanges  52  have a Z-profile, and are attached to lateral walls  53  of the structural casing  12 . According to an embodiment, the flanges  52  are bolted to the lateral walls  53 . Therefore, the flanges  52  are made of a relatively thin metal, such as bent sheet metal, whereby they form a joint between the lateral walls  53  and the expandable shell  50 . The joint is essentially equivalent to a pair of hinges. 
         [0034]    Ribs  54  may also be provided between the flanges  52  on the wall segments  51 , on an end wall  55  of the expandable shell  50 , and/or on an end wall  56  of the structural casing  12 . Accordingly, the ribs  54  will limit the expansion of the expandable shell  50  by abutting against the structural casing  12 , whereby the expandable shell  50  will maintain a generally uniform shape when expanding. Moreover, the ribs  54  may be used to maintain insulation material in place. Other configurations are also considered to allow a controlled expansion of the shell  50 . 
         [0035]    As observed in  FIG. 2 , the expandable shell  50  has openings  57  for connection with the ventilation units  30 . Due to the expanding nature of the expandable shell  50 , the ventilation units  30  may be connected to the expandable shell  50  by way of flexible insulated ducts. 
         [0036]    Referring to  FIG. 5 , an exhaust pipe  60  is shown in fluid communication between the apparatus  10  and a separator basin  62 . The separator basin  62  is used to remove any solid particles from the thermo-transformation air. More specifically, it is anticipated that the thermo-transformation process will create residue in the air such as airborne solids and volatile organic compounds (i.e., polluted air). Referring to  FIGS. 5 to 7 , the separator basin  62  has a casing in which a pool of liquid such as water is held. As shown in  FIG. 6 , the exhaust pipe  60  extends into the pool of liquid, whereby the polluted air reaching the separator basin  62  will pass through the liquid. Therefore, the solids will be retained by the liquid of the separator basin  62 . 
         [0037]    Referring to  FIGS. 5 and 7 , a perforated panel  64  is shown and is positioned inside the separator basin  62  to stabilise the pool of liquid despite the fact that hot gas is blown into the liquid. Accordingly, feed pipe  66  will exhaust pressure from the separator basin  62  with limited moisture content. The feed pipe  66  will direct the exhaust from the separator basin  62  to a burner  68 . The burner  68  will be used for the combustion of any volatile organic compounds. 
         [0038]    Referring to  FIG. 8 , an exhaust recuperation unit is generally shown at  70 . The exhaust recuperation unit  70  is typically positioned above the door  13  of the apparatus  10 , for exhausting odorous gases when the door  13  is opened. The exhaust recuperation unit  70  has appropriate vanes  72  to collect hot air exiting from the casing  12  of the apparatus  10 , primarily when the door  13  is opened. A sequence of recuperation coil  74  and fans  76  will create an air flow in the exhaust recuperation unit  70 . The recuperation coil  74  encloses a refrigerant that will collect heat from the air circulating in the exhaust recuperation unit  70 . Subsequently, the air is exhausted via exhaust pipe  78 . The recuperated energy may be used for heating purposes, or to meet any nearby heat demand. 
         [0039]    It is pointed out that the exhaust recuperation unit  70  may be positioned at other locations relative to the apparatus  10 . Moreover, the apparatus  10  may fully operate without the presence of the exhaust recuperation unit  70 . 
         [0040]    In some instances, it may be required to subject the torrefied wood planks to a cooling treatment. Referring to  FIG. 9 , there is shown cooling apparatus  80  in which the torrefied wood planks are positioned as a post-treatment step. According to the embodiment, the cooling apparatus  80  is aligned with the apparatus  10  such that the trolley  42  may be transferred in a straight path from the apparatus  10  to the cooling apparatus  80 . 
         [0041]    The cooling apparatus  80  has a cooling chamber  82  in which the temperature and moisture are controlled. The cooling chamber  82  is defined by perforated walls  84  similar in construction to the perforated walls  14  of the apparatus  10 . Accordingly, the perforated walls  84  have throttle disks  86  to control the amount of air reaching the cooling chamber  82 . A fan  88  with appropriate filters  90  will inject fresh air into the cooling chamber  82 , to cause a cycling of the air within the cooling apparatus  80  to ensure that the wood planks are subjected to relatively uniform cooling parameters. As mentioned previously, rails  92  may be used for the displacement of the trolley in and out of the cooling apparatus  80 .