JP5100232B2 - Wood pellet combustion equipment - Google Patents

Description

  The present invention relates to a wood pellet combustion apparatus for burning wood pellets made by pulverizing and compressing thinned wood.

In a conventional wood pellet combustion apparatus (see, for example, Patent Document 1), wood pellets supplied to the upper surface of a combustion shelf are ignited by an electric heater.
Japanese Patent Laid-Open No. 2005-9768

  By the way, wood pellets have various types of trees that are used as raw materials, various parts of use, and various diameters, lengths, bulk specific gravity, and the like. For this reason, depending on the type of the wood pellet, the ignition time when igniting with an electric heater or the like may be long.

  An object of the present invention is to obtain a wood pellet combustion apparatus that can shorten the ignition time of wood pellets in consideration of the above facts.

A wood pellet combustion apparatus according to claim 1 is a combustion section for burning wood pellets, ignition means for igniting the wood pellets supplied to the combustion section, and supplying wood pellets to the combustion section. A supply crushing means for crushing the wood pellets when the wood pellets to be ignited by the ignition means are supplied to the combustion part, and the supply crushing means communicates with the combustion part at one end side, A conveying path through which the wood pellets are supplied, and a spiral blade that is provided in the conveying path and rotated to one side around the axis so that the blade conveys the wooden pellet in the conveying path A conveying screw that conveys the wood pellets in the conveying path to the other end side of the conveying path by being conveyed to one end side of the path and being rotated around the axis to the other, When the conveying screw is rotationally driven and when the conveying screw is rotationally driven to convey the wood pellets to be ignited by the ignition means to the combustion unit, the conveying screw is rotated around one axis and the other around the axis. Drive means for alternately rotating the lens at least once and then rotating it around the axis .

In the wood pellet combustion apparatus according to claim 1, the supply crushing means crushes the ignition wood pellet when supplying the wood pellet to be ignited by the ignition means to the combustion section. The crushed ignition wood pellets are supplied to the combustion section by the supply crushing means and ignited by the ignition means. Specifically, the drive means of the supply crushing means, when rotating the conveying screw in order to convey the wood pellets ignited by the igniting means to the combustion section, first, the conveying screw is turned around one axis and the other around the axis. Alternately rotate at least once. For this reason, the wood pellet in a conveyance path is conveyed alternately by the blade | wing of a screw for conveyance to the one end side and other end side of a conveyance path. Therefore, the wood pellets can be crushed by the wood pellets colliding with each other during the conveyance. After that, when the driving means rotates the conveying screw to one side around the axis, the crushed wood pellets (ignition wood pellets) are conveyed to one end side (combustion part side) of the conveying path, and the ignition means It is ignited. In this way, the wood pellets with improved ignitability by being crushed are ignited, so that the ignition time can be shortened.

  As described above, in the wood pellet combustion apparatus according to the present invention, the ignition time of the wood pellet can be shortened.

<First Embodiment>
The structure of the pellet stove 10 as a wood pellet combustion apparatus which concerns on the 1st Embodiment of this invention is shown by the typical longitudinal cross-sectional view by FIG. FIG. 2 shows a schematic cross-sectional view of the configuration of the pellet stove 10.

  In the figure, the arrow FR indicates the forward direction of the pellet stove 10, the arrow UP indicates the upward direction of the pellet stove 10, and the arrow W indicates the width direction of the pellet stove 10.

  The pellet stove 10 includes a housing 12 formed in a hollow rectangular parallelepiped shape. A hopper 16 serving as a fuel tank is provided inside the housing 12. Inside the hopper 16, wood pellets 14, which are processed fuel made by pulverizing and compressing thinned wood, are stored. In the first embodiment, the wood pellet 14 has a diameter of about 4 mm to 7 mm and a length of about 5 mm to 20 mm, and is made relatively fragile.

  Below the hopper 16, a fuel transfer device 18 constituting supply crushing means is provided. The fuel transfer device 18 includes an upper pipe 19 formed in a bottomed cylindrical shape. The upper pipe 19 is arranged in a state where the axial direction is along the front-rear direction of the pellet stove 10 and the bottom wall faces the front side of the pellet stove 10, and the rear end side is connected to the lower end portion of the hopper 16. The inside of the upper pipe 19 communicates with the inside of the hopper 16, and the wood pellet 14 in the hopper 16 flows into the inside of the upper pipe 19.

  As shown in FIG. 3, an upper screw 20 serving as a metering screw is provided in the upper pipe 19. The upper screw 20 has a shaft 20 </ b> A disposed coaxially with the upper pipe 19. One end of the shaft 20A in the axial direction is connected to the motor 24 via a speed reduction mechanism (not shown), and the shaft 20A is rotated by the driving force of the motor 24.

  A spiral blade 20B (so-called spyler) is integrally provided on the outer periphery of the shaft 20A. The outer diameter of the blade 20B is slightly smaller than the inner diameter of the upper pipe 19, and the wood pellets 14 flowing into the upper pipe 19 enter between the blades 20B. The wood pellet 14 that has entered between the blades 20B is conveyed to the front end side (arrow FR side) of the upper pipe 19 by the blades 20B when the shaft 20A is rotated to one side around the axis together with the blades 20B. Yes.

  A chute 28 is connected to the lower side of the front end portion of the upper pipe 19. The chute 28 is formed in a box shape (square tube shape) with both upper and lower ends open, and the inside communicates with the upper pipe 19. For this reason, the wood pellet 14 conveyed to the front end side of the upper pipe 19 by the blade 20B of the upper screw 20 is supplied into the chute 28 and falls.

  On the other hand, below the chute 28, a lower pipe 21 (conveying path) formed in a cylindrical shape is provided. The lower pipe 21 is arranged in a state where the axial direction is along the front-rear direction of the pellet stove 10, and the lower end portion of the chute 28 is connected to the upper side of the intermediate portion in the axial direction. The inside of the lower pipe 21 communicates with the inside of the chute 28, and the wood pellet 14 that has dropped inside the chute 28 is supplied to the inside of the lower pipe 21.

  A lower screw 22 is disposed inside the lower pipe 21 as a conveying screw. The lower screw 22 has a shaft 22 </ b> A disposed coaxially with the lower pipe 21. One end of the shaft 22A in the axial direction is connected to the motor 25 via a speed reduction mechanism (not shown). The motor 25 constitutes a driving means, and the shaft 22A is rotated by the driving force of the motor 25.

  A spiral blade 22B (so-called spiler) is integrally provided on the outer periphery of the shaft 22A. The outer diameter of the blade 22B is slightly smaller than the inner diameter of the lower pipe 21, and the wood pellet 14 supplied to the inside of the lower pipe 21 enters between the blades 22B. . The wood pellet 14 that has entered between the blades 22B is conveyed to the front end side (arrow FR side) of the lower pipe 21 by the blades 22B when the shaft 22A is rotated to one side around the axis together with the blades 22B. When rotated to the other side along the axis along with 22B, the blade 22B conveys it to the rear end side (counter arrow FR side) of the lower pipe 21.

  In addition, a flange portion 22C that protrudes in the shape of a flange toward the radially outer side is provided at an axially intermediate portion of the shaft 22A. The outer circumferential portion of the flange portion 22 </ b> C is formed concentrically with the lower pipe 21 and is disposed close to the inner circumferential surface of the lower pipe 21. For this reason, the wood pellet 14 supplied into the lower pipe 21 is restricted from moving to the rear end side of the lower pipe 21 by interfering with the flange portion 22C.

  On the other hand, the front end portion of the lower pipe 21 is inserted into a through hole formed in the partition plate 48 that partitions the inside of the housing 12 back and forth. For this reason, the inside of the lower pipe 21 communicates with the combustion chamber 30 provided in the housing 12 on the side opposite to the fuel transfer device 18 via the partition plate 48. In the combustion chamber 30, a flat plate-shaped rooster 32 as a combustion shelf constituting a combustion section is arranged, and the wood pellets 14 conveyed to the front end side of the lower pipe 21 by the blades 22 </ b> B of the lower screw 22 It is supplied (conveyed) to the upper surface of 32 (see arrow A in FIG. 1).

  A rod-shaped electric heater 34 as an ignition means is provided below the rooster 32. The electric heater 34 is a so-called “ceramic heater” in the first embodiment, and is disposed in a state inclined at a predetermined angle with respect to the plate surface of the rooster 32. The electric heater 34 is fixed to the lower surface of the rooster 32 through a stay fixed to the lower surface of the rooster 32.

  The front end portion of the electric heater 34 is inserted through a through hole 36 formed in the rooster 32 and protrudes from the upper surface of the rooster 32 by a predetermined amount. For this reason, when the wood pellet 14 is supplied to the upper surface of the rooster 32 as described above, the tip of the electric heater 34 is covered with the wood pellet 14.

  A plurality of air injection holes 40 are formed in the rooster 32, and air (primary air, FIG. 1) blown into the air intake chamber 44 from a fan 42 (blower) installed below the fuel transfer device 18. (See arrow B) passes through the air nozzle hole 40 and is blown (ventilated) into the combustion chamber 30.

  Further, the air blown from the fan 42 also flows into the air passage 46 (see arrow C in FIG. 1), and is blown into the combustion chamber 30 from the air injection holes 50 formed in the partition plate 48 (secondary). air). Further, the air that has flowed into the air passage 46 also flows into the air return passage 52 branched to the fuel transfer device 18 side, and is ejected from above the chute 28 of the fuel transfer device 18.

  Here, the motors 24 and 25, the electric heater 34, and the fan 42 of the fuel transfer device 18 described above are connected to the control device 38 via wiring (not shown). The control device 38 constitutes drive means (supply crushing means) together with the fuel transfer device 18 and controls the operation of the motors 24 and 25, the electric heater 34, and the fan 42 according to a predetermined control program. .

  Specifically, when an operation switch (not shown) mounted on the pellet stove 10 is turned “ON”, the control device 38 operates the fan 42 and starts energizing the electric heater 34. At this time, the control device 38 operates the fuel transfer device 18 to supply the wood pellets 14 for ignition (wood pellets 14 ignited by the electric heater 34) to the upper surface of the rooster 32.

  In this case, the control device 38 first rotates the motor 24 in the normal direction to rotate the upper screw 20 around one axis. As a result, the wood pellets 14 in the upper pipe 19 are conveyed to the front end side of the upper pipe 19 by the upper screw 20, dropped in the chute 28, and supplied into the lower pipe 21. The control device 38 stops the motor 24 when a predetermined time elapses after the motor 24 is rotated forward (when a predetermined amount of the wood pellet 14 is supplied into the lower pipe 21).

  Next, the control device 38 rotates the motor 25 in the normal direction and reverse direction at a constant cycle, and alternately rotates the lower screw 22 around the axis line and one around the axis line a plurality of times. At this time, the control device 38 controls the energization time to the motor 25 so that the wood pellet 14 in the lower pipe 21 does not reach the upper surface of the rooster 32.

  Then, the control device 38 rotates the motor 25 forward and backward at a constant cycle as described above, and then rotates the motor 25 forward for a predetermined time, and the lower screw 22 causes the wood pellet 14 in the lower pipe 21 to move upward. Transport to. Thereby, the front-end | tip part of the electric heater 34 is covered with the wood pellet 14. FIG. Since the electric heater 34 generates heat by energization, the wood pellet 14 (ignition wood pellet 14) covering the tip of the electric heater 34 is heated and ignited (ignited). In addition, the control apparatus 38 interrupts | blocks the electricity supply to the electric heater 34, if predetermined time passes after starting the electricity supply to the electric heater 34 (it is for a while after the wood pellet 14 is ignited). Further, the primary air blown from the fan 42 is supplied to the upper surface side of the rooster 32, whereby the wood pellets 14 on the upper surface of the rooster 32 are burned.

  When the wood pellet 14 on the upper surface of the rooster 32 is burning as described above, the control device 38 intermittently operates the motor 24 and the motor 25 to sequentially move the wood pellet 14 in the hopper 16 to the upper surface of the rooster 32. Transport to. Thereby, the combustion state of the wood pellet 14 on the upper surface of the rooster 32 is maintained.

  On the other hand, a heat shield plate 35 formed in a U shape as viewed from above is provided above the rooster 32. The heat shield plate 35 suppresses the heat of the flame rising above the rooster 32 due to the combustion of the wood pellets 14 from being transmitted to the side wall of the housing 12.

  The combustion of the wood pellets 14 may cause the combustible chamber 30 to be filled with dry combustible gas, which may inhibit the combustion of the wood pellets 14, but the air is supplied from the fan 42 and is supplied from the air injection holes 50 into the combustion chamber 30. Combustion of the dry-distillable combustible gas is promoted by the above-described secondary air ejected into the air.

  In addition, the air supplied from the fan 42 and blown from above the chute 28 of the fuel transfer device 18 through the air passage 46 and the air return passage 52 is the combustion gas generated in the combustion chamber 30. Prevent backflow to the side.

  Further, above the combustion chamber 30, a smoke cylinder 62 formed in a cylindrical shape is provided on the upper wall of the housing 12. The inside of the smoke cylinder 62 communicates with the inside of the combustion chamber 30. A baffle plate 64 made of a flat plate material is provided inside the combustion chamber 30, and a gas passage 66 is formed between the side wall 12 of the housing and the baffle plate 64. In the gas passage 66, a plate-like perforated plate 68 having a plurality of through holes is provided, and the exhaust gas generated in the combustion chamber 30 passes through the gas passage 66 and the inside of the smoke cylinder 62. The exhaust gas is exhausted to the outside of the pellet stove 10 and is discharged, for example, outdoors via an exhaust pipe (not shown) connected to the smoke cylinder 62.

  Further, an ash receiving tray 58 is disposed below the rooster 32, and the burned residue (ash) of the burned wood pellet 14 is newly replenished onto the rooster 32 by the upper screw 20 and the lower screw 22. It is pushed out by the wood pellet 14 and falls into the ash tray 58. A guide frame 60 for guiding the ash dropped from the rooster 32 into the ash tray 58 is provided between the rooster 32 and the ash tray 58. Further, the wood pellet 14 does not become a powder form even if burned out, and becomes an ash with a little left in its original form, so that a small amount of ash falls from the air injection hole 40 of the rooster 32, but the air injection hole 40. The ash of the wood pellet 14 that has fallen into the air intake chamber 44 also falls into the ash receiving tray 58.

  Next, the operation of the first embodiment will be described.

  In the pellet stove 10 configured as described above, when an operation switch (not shown) is turned “ON”, the control device 38 operates the fan 42 and starts energizing the electric heater 34. At this time, the control device 38 rotates the motor 24 in the normal direction to rotate the upper screw 20 to one side around the axis for a predetermined time in order to supply the wood pellet 14 for ignition to the upper surface of the rooster 32. As a result, a predetermined amount of the wood pellet 14 is conveyed to the front end side of the upper pipe 19 by the upper screw 20, falls in the chute 28, and is supplied into the lower pipe 21.

  Next, the control device 38 rotates the motor 25 in the normal direction and reverse direction at a constant cycle, and alternately rotates the lower screw 22 around the axis line and one around the axis line a plurality of times. Therefore, the wood pellets 14 (ignition wood pellets 14) in the lower pipe 21 are alternately conveyed to the front end side and the rear end side of the lower pipe 21 by the blades 22B of the lower screw 22, and at the time of this conveyance It can be crushed into pieces by hitting each other.

  Then, the control device 38 causes the motor 25 to rotate in the normal direction for a predetermined time after rotating the motor 25 in the normal rotation and reverse rotation at regular intervals as described above. Therefore, the ignition wood pellet 14 crushed in the lower pipe 21 as described above is conveyed to the upper surface of the rooster 32 by the lower screw 22, and the tip of the electric heater 34 is the ignition wood pellet. 14. Since the electric heater 34 generates heat by energization, the ignition wood pellet 14 covering the tip of the electric heater 34 is heated and ignited.

  As described above, in the first embodiment, since the ignition wood pellet 14 is crushed into a rag shape, the ignitability is improved and the contact between the ignition wood pellet 14 and the electric heater 34 is improved. (The contact area between the two increases.) Therefore, the ignition time of the wood pellet 14 by the electric heater 34 can be greatly shortened (for example, it becomes possible to ignite in about 2 minutes).

  As described in the background art section, the wood pellets 14 have various types of trees used as raw materials and various parts of use, and have various diameters, lengths, bulk specific gravity, and the like. For this reason, there is a large variation in the ignitability of the wood pellets 14 and, conventionally, there has also been a large variation in the ignition time when igniting with the electric heater 34 (for example, it takes about 5 to 8 minutes to ignite). )

  In this regard, in the first embodiment, the ignition wood pellets 14 are crushed in a rough shape, so that variations in ignitability are reduced. Therefore, the variation in the ignition time when ignited by the electric heater 34 can be reduced, and the ignition by the electric heater 34 can be made stable.

  Moreover, in the first embodiment, since the control device 38 is configured to crush the wood pellets 14 by controlling the operation of the motors 24 and 25, a special mechanism for crushing the wood pellets 14 is added. The wood pellet 14 can be crushed with an extremely simple configuration.

  In the first embodiment, when the wood pellet 14 in the lower pipe 21 is crushed by the rotation of the lower screw 22, the crushed particles of the wood pellet 14 do not become smaller than the air nozzle hole 40 of the rooster 32. It is preferable to set the rotation time and rotation speed of the motor 25. This also applies to other embodiments of the present invention described below.

Next, another embodiment of the present invention will be described. In addition, about the structure and operation | movement fundamentally similar to the said 1st Embodiment, the same sign as the said 1st Embodiment is provided, and the description is abbreviate | omitted. The second and third embodiments described below are reference examples, and are not included in the technical scope of the invention described in claim 1.
<Second Embodiment>
FIG. 4 is a schematic longitudinal sectional view showing the configuration of a pellet stove 70 according to the second embodiment of the present invention. The pellet stove 70 has basically the same configuration as the pellet stove 10 according to the first embodiment, but closes the front end opening (the left opening in FIG. 4) of the lower pipe 21. The closing mechanism 72 is provided. The closing mechanism 72 constitutes closing means together with the control device 38, and includes a motor 74 disposed below the air return passage 52. The motor 74 is electrically connected to the control device 38, and one end of the shaft 76 in the axial direction is connected to the output shaft. The other axial end of the shaft 76 penetrates the partition plate 48 and projects into the combustion chamber 30. A closing member 78 formed in a flat plate shape is provided in the combustion chamber 30, and the other axial end of the shaft 76 is connected to one end of the closing member 78. The closing member 78 has a closing position (see a solid line in FIG. 4) for closing the front end opening of the lower pipe 21 and an opening position for opening the front end opening of the lower pipe 21 by the motor 74 rotating the shaft 76. (Refer to the two-dot chain line in FIG. 4).

  Here, in this embodiment, the control device 38 rotates the motor 25 in the forward direction after supplying the wood pellets 14 for ignition into the lower pipe 21 by the rotation of the upper screw 20 as in the first embodiment. Thus, the lower screw 22 is rotated to one side around the axis for a predetermined time. Moreover, at this time, the control device 38 operates the motor 74 to temporarily place the closing member 78 at the closing position. For this reason, the wood pellet 14 conveyed to the front end side of the lower pipe 21 by the blade 22B of the lower screw 22 is agitated by the blade 22B in a state in which the movement toward the rooster 32 is restricted by the closing member 78. Thereby, the wood pellet 14 is crushed in a rough shape. Then, the control device 38 operates the motor 74 to move the closing member 78 to the open position when a predetermined time elapses after the closing member 78 is arranged at the closing position. For this reason, the wood pellets 14 crushed in a crumbly manner as described above are conveyed to the upper surface of the rooster 32 by the blades 22 </ b> B of the lower screw 22.

Also in this embodiment, since the wood pellets 14 for ignition are crushed in a rough shape, the ignition time of the wood pellets 14 by the electric heater 34 can be shortened, and basically the same operation as in the first embodiment. There is an effect.
<Third Embodiment>
According to the third embodiment of the present invention, the configuration is basically the same as that of the first embodiment. However, in this embodiment, the control method of the motor 25 by the control device 38 when the operation switch is turned “ON” is different from the first embodiment.

  That is, in this embodiment, after supplying the wood pellets 14 for ignition into the lower pipe 21 by the rotation of the upper screw 20, the control device 38 reverses the motor 25 for a predetermined time to move the lower screw 22 around the other axis. Rotate for a predetermined time. For this reason, the wood pellet 14 for ignition supplied in the lower pipe 21 is conveyed to the flange 22C side by the blades 22B of the lower screw 22, and moved to the rear end side of the lower pipe 21 by the flange 22C. Is stirred by the blade 22B in a restricted state. Thereby, the wood pellet 14 for ignition is crushed in the shape of a rag. Then, the control device 38 reverses the motor 25 for a predetermined time as described above, and then rotates the motor 25 in the normal direction for a predetermined time to rotate the lower screw 22 around the axis for a predetermined time. For this reason, the wood pellet 14 crushed as described above is conveyed to the upper surface of the rooster 32 by the blades 22 </ b> B of the lower screw 22.

  Also in this embodiment, since the wood pellets 14 for ignition are crushed in a rough shape, the ignition time of the wood pellets 14 by the electric heater 34 can be shortened, and basically the same operation as in the first embodiment. There is an effect.

  In the first to third embodiments, the fuel conveying device 18 constituting the supply crushing means includes the lower screw 22 as a conveying screw, and the wood pellet 14 is crushed by the lower screw 22. However, the present invention is not limited to this, and the configuration of the supply crushing means can be changed as appropriate.

  Moreover, although the said 1st Embodiment-said 3rd Embodiment demonstrated the case where this invention was applied with respect to the pellet stove which uses a wood pellet as a fuel, this invention is a boiler etc. which use a wood pellet as a fuel. It can also be applied to.

It is a typical longitudinal section showing the composition of the pellet stove concerning a 1st embodiment of the present invention. It is a typical cross-sectional view which shows the structure of the pellet stove concerning the 1st Embodiment of this invention. It is a perspective view which shows the structure of the peripheral member containing the fuel conveying apparatus of the pellet stove which concerns on the 1st Embodiment of this invention. It is a typical longitudinal section showing the composition of the pellet stove concerning a 2nd embodiment of the present invention.

Explanation of symbols

10 Pellet stove (wood pellet combustion equipment)
14 Wood pellets 18 Fuel transfer device (supply crushing means)
21 Lower pipe (conveyance path)
22 Lower screw (Screw for conveyance)
25 Motor (drive means)
32 Rostor (combustion part)
34 Electric heater (ignition means)
38 Control device (supply crushing means, driving means, closing means)
70 Pellet stove 72 Blocking mechanism (blocking means)

Claims (1)

A combustion section for burning wood pellets;
Ignition means for igniting the wood pellets supplied to the combustion section;
Supplying the wood pellets to the combustion part, and supplying the wood pellets to be ignited by the ignition means to the combustion part, supply crushing means for crushing the wood pellets,
With
The supply crushing means includes
One end side communicates with the combustion section, and a conveying path through which wood pellets are supplied,
It is provided in the conveyance path, has a spiral blade, and is rotated around one axis so that the blade conveys the wood pellets in the conveyance path to one end side of the conveyance path, and around the axis. A screw for conveying the blade to convey the wood pellet in the conveying path to the other end side of the conveying path by being rotated to the other;
When the conveying screw is rotationally driven and the conveying screw is rotationally driven to convey the wood pellets ignited by the ignition means to the combustion section, the conveying screw is rotated around one axis and around the axis. A driving means for alternately rotating at least once to the other and then rotating to the other around the axis;
Wood pellet combustion apparatus having

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