JP2010078269A - Pellet combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellet combustor with high combustion performance. <P>SOLUTION: A combustion tray 5 of a lower part of a combustion chamber 80 is formed in a conical shape comprising a fire grate 54 and a side wall 52, a grate hole 60 is provided in the fire grate 54, and a side wall hole 61 having an inclination with respect to a straight line toward a center direction as seen from above is provided in the side wall 52. By causing a swirl flow by blowing out primary air into the combustion tray 5 from the grate hole 60 and the side wall hole 61, air of an amount sufficient for combustion of pellets is secured, and blocking of the grate hole 60 and the side wall hole 61 is prevented by solidifying ash since the ash is lifted and agitated. A flow of secondary air blown out from an air hole set 47 provided in an inner side wall 41 of the combustion chamber 80 is changed to form a swirl flow by a louver 45, flame of burning pellets is concentrated in a center part, and even unburned gas is concentrated in a flame part to carry out re-combustion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pellet combustion apparatus that burns pellets formed by solidifying wood chips and the like.

Conventionally, as an apparatus that burns pellets formed by pressing and compacting wood chips and uses the heat, there is one described in, for example, Japanese Patent Application Laid-Open No. 2006-317025.
In this method, a mortar-shaped container is formed by a rooster (grate) and a side wall that rises obliquely, and pellets are placed in the container and burned.
In addition to the lattice holes of the rooster, the side walls are provided with a plurality of air holes that open to the inclined surface. By blowing air from the air holes toward the pellets, the combustion efficiency of the pellets is increased, and the woody In the case of the system pellets, the aim is to float the pellets and ash from the rooster in order to prevent the ash from sticking to the lattice holes due to tar components.
JP 2006-317025 A

However, the blowing direction of the air hole provided on the side surface is parallel to the surface of the rooster and in the direction toward the center of the combustion chamber, and a sufficient amount of air cannot be supplied to the deposited pellets. There is a problem that the upward air alone is not sufficient to lift pellets and ash from the rooster. Therefore, in the above-described conventional example, since the pellet and ash are stirred with the stirring piece on the rooster by further rotating the rooster with a motor, the inconvenience of complicated structure and high cost cannot be avoided.
In view of the above problems, an object of the present invention is to provide a pellet combustion apparatus having a simple structure, high combustion performance, and capable of effectively preventing ash solidification.

  The present invention relates to a pellet combustion apparatus for burning pellets in a combustion dish provided at a lower part of a combustion chamber, wherein the combustion dish is located at the center of the combustion chamber when viewed from above, and includes a grate and an outside of the grate. It consists of a side wall that widens the diameter as it rises from the periphery at the first inclination angle and goes upward, and the grate is provided with a plurality of grate holes, and the side wall of the grate when the combustion dish is viewed from above A plurality of side wall holes directed in the direction of the second inclination angle with respect to the straight line directed to the gas are provided, and primary air is supplied into the combustion dish through the lattice holes and the side wall holes from the primary air chamber formed on the lower side of the combustion dish. Thus, a swirl flow is generated in the combustion dish.

According to the present invention, by generating a swirling flow, the pellet flame can be concentrated at the central portion to maintain a high temperature, and the combustion efficiency and the exchange efficiency when using heat can be improved.
In addition, the pellets and ash in the combustion dish are floated and stirred by the cooperation of swirling flow and blowing from the lattice holes, so that the combustion of the pellets is promoted and the ash adheres to the inner surface of the combustion dish and solidifies. It is possible to prevent the lattice holes and the side wall holes from being blocked.

Next, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view of a pellet combustion apparatus. 2A is a top view of the combustion dish, and FIG. 2B is a cross-sectional view around the side wall hole of the combustion dish. Furthermore, FIG. 3 is a figure which shows the AA part cross section in FIG.
The pellet combustion apparatus 1 includes a combustion apparatus body 10, a pellet supply apparatus 2 that supplies wood pellets to the combustion apparatus body 10, and a blower 3 that sends combustion air to the combustion apparatus body 10.

The combustion apparatus body 10 includes an outer case 4 including a cylindrical outer wall 42, a ceiling plate 43 that covers the upper opening of the outer wall 42, and a bottom plate 44 that covers the lower opening of the outer wall 42. .
The inside of the outer case 4 is vertically divided by a partition wall 11 that supports the combustion dish 5 in the center, and a cylindrical inner wall extending from the ceiling plate 43 to the partition wall 11 with a gap between the upper wall and the outer wall 42. 41 is provided to form a combustion chamber 80 surrounded by the inner wall 41.

The combustion dish 5 has a disk-shaped grate 54 as a bottom wall, and has a side wall 52 that rises at an inclination angle that increases in diameter as it goes upward from the outer peripheral edge of the grate 54. 11 is connected. The side wall 52 has a donut shape when viewed from above.
The partition wall 11 is provided with a cylindrical guide 51 that surrounds the upper end of the side wall 52 of the combustion dish 5 and extends upward.
A space between the outer side wall 42 and the inner side wall 41 is a secondary air chamber 82 described later.

Since the pellets are combusted in the combustion chamber 80, heat resistant metal or the like is used as the material for the combustion dish 5, the partition wall 11, the inner wall 41, the outer wall 42, the ceiling plate 43, the guide 51, and the like.
The combustion dish 5 and the guide 51, and further, if necessary, the partition wall 11 can be formed by integrally combining a plurality of pressed members, or can be formed as an integrated object by cutting or the like.

In the lower space of the outer case 4 partitioned by the partition wall 11, a cylindrical partition wall 55 is provided from the partition wall 11 to the bottom plate 44 so as to surround the combustion dish 5, and the inside of the partition wall 55 serves as a primary air chamber 81. A space between the wall 42 and the partition wall 55 is an air introduction chamber 83.
The pellet supply device 2 includes a hopper 20 that contains pellets, and a supply passage 21 that extends from the hopper 20 through the outer wall 42 and the inner wall 41 into the combustion chamber 80. Pellets are supplied into the combustion dish 5 from the hopper 20 through the supply passage 21.

The primary air chamber 81 is provided with an ash receiver 6 for receiving the ash after burning the pellets on the bottom plate 44. It is preferable that the ash receiver 6 has a width that covers the grate 54 and the side wall hole 61 of the combustion dish 5.
The ash receiver 6 can be taken out of the outer case 4 from doors (not shown) provided on the partition wall 55 and the outer wall 42 that can be opened and closed.

The blower 3 is connected to the primary air chamber 81 by a blower pipe 31 </ b> A that penetrates the outer wall 42.
From the blower pipe 31 </ b> A, the blower pipe 31 </ b> B branches outside the combustion apparatus main body 10, and the blower pipe 31 </ b> B is connected to the air introduction chamber 83. The partition wall 11 is provided with a plurality of introduction holes 56 that allow the secondary air chamber 82 and the air introduction chamber 83 to communicate with each other.

The side wall 52 of the combustion dish 5 has an inclination angle α with respect to the grate 54 as shown in FIG. 2B in order to efficiently collect the pellets put in the combustion dish 5 to the center. The inclination angle α is preferably 45 to 65 °.
The grate 54 includes a plurality of lattice holes 60, and the side wall 52 is provided with a plurality of side wall holes 61 in the circumferential direction at a predetermined height from the grate 54. The height position of the side wall hole 61 is set to be equal to or lower than the minimum deposition height at the time of supply of pellets to be put into the combustion dish 5, for example, within the range of the lower third of the height between the grate 54 and the partition wall 11. Is preferred.

As shown in FIG. 2A, the direction of the hole of the side wall hole 61 is set to have an inclination angle β with respect to the radial line X of the side wall 52, and as shown in FIG. The cross section is set so as to be perpendicular to the surface of the side wall 52, but it is sufficient that at least the blowout from the side wall hole 61 is upward. Further, the inclination angle β is preferably 45 °, but it is sufficient that at least the blowout blows out along the side wall 52 of the combustion dish 5 so as to form a swirling flow.
As a result, the primary air supplied from the blower 3 to the primary air chamber 81 is blown upward from the lattice holes 60 to raise the pellets in the combustion dish 5 and is also blown into the combustion dish 5 from the side wall holes 61. Thus, in the example of FIG. 2A, a swirl flow swirling counterclockwise is generated.
The solid line arrows in FIGS. 1 and 2 indicate the flow of primary air.

Next, as shown in FIGS. 1 and 3, holes 47a, 47b, 47c, and 47d are arranged in the vertical direction on the inner wall 41 that forms the combustion chamber 80 on the inner side and the secondary air chamber 82 on the outer side. A pair of air holes 47 are provided at opposite positions in the circumferential direction. The direction of each hole of the air hole set 47 is toward the center of the combustion chamber 80 and is perpendicular to the surface of the inner wall 41 in the vertical direction.
A louver 45 is provided inside the inner wall 41 along the hole array of the air hole set 47. The louver 45 has an inclination angle γ with respect to the direction of the hole so as to cover the air hole set 47. The inclination direction of the louver 45 is the same as the direction of the side wall hole 61 in the combustion dish 5, and the inclination angle γ is preferably 45 °. The number of holes in the air hole set 47 is increased or decreased according to the volume of the combustion chamber 80.

Secondary air is supplied to the secondary air chamber 82 from the blower pipe 31 </ b> B through the air introduction chamber 83 and from a plurality of introduction holes 56, and blown out from the air hole set 47 into the combustion chamber 80. The secondary air blown out from the air hole set 47 is transformed into a direction along the inclination by the louver 45.
Thereby, the secondary air becomes a counterclockwise swirl flow in the combustion chamber 80.
The broken line arrows in FIGS. 1 and 3 indicate the flow of secondary air.

Inside the combustion chamber 80, a metal baffle 7 is attached to the ceiling plate 43 at a position facing the heat extraction hole 46 by a suspension member 71.
The baffle 7 is formed into a conical shape by press working or the like, and is arranged so that the tip end side of the conical shape faces the combustion dish 5 side.

Next, the operation of the pellet combustion apparatus 1 having the above configuration will be described. FIG. 4 is a schematic view when the pellet is burned.
The pellets 100 supplied from the pellet supply device 2 to the combustion chamber burn on the combustion dish 5.
Since the primary air is blown out from the lattice hole 60 of the grate and the side wall hole 61 of the side wall into the combustion dish 5, the pellet 100 is lifted and swirled, and a stirring state is generated. At this time, the blowing direction of the primary air from the side wall hole 61 is also inclined upward rather than in the horizontal direction, which contributes to lifting the pellet.

Thereby, the primary air required for combustion is uniformly supplied to the pellets 100 in the combustion dish 5 without unevenness.
The flame of the burning pellet 100 is prevented from extending and extending to the inner wall 41 of the combustion chamber 80 by the guide 51 provided in the vicinity of the upper end opening edge of the combustion dish 5, and is guided to the center of the combustion chamber.

Further, since the secondary air is blown out from the air hole set 47 of the inner wall 41 into the combustion chamber 80 as a swirling flow in the same direction as the swirling of the primary air, the unburned gas is also caused by the synergistic effect of the two swirling flows. Concentrate on.
Further, the baffle 7 provided in the heat extraction hole 46 of the ceiling shown in FIG. 1 does not immediately discharge the combustion gas to the outside, but returns a part of the combustion gas to the flame part again. As a result, the unburned gas is completely burned.
The ash after the pellets burn in the combustion dish 5 accumulates in the ash receiver 6 through the lattice holes 60 and the side wall holes 61.

  In the present embodiment, the inner side wall 41 corresponds to the side wall of the combustion chamber in the present invention, and the air hole set 47 and the louver 45 constitute the secondary air swirling and blowing means in the present invention.

  The present embodiment is configured as described above, and the combustion dish 5 positioned at the lower center of the combustion chamber 80 is inclined upward from the grate 54 and the outer peripheral edge of the grate when viewed from above. The grate 54 is provided with a plurality of lattice holes 60, and the side wall 52 has a straight line toward the center of the grate 54 when the combustion dish 5 is viewed from above. A plurality of inclined side wall holes 61 are provided, and primary air is supplied into the combustion dish 5 from the primary air chamber 81 formed on the lower side of the combustion dish 5 through the lattice holes 60 and the side wall holes 61. Air can also be supplied to the contact portion between the difficult pellet and the combustion dish 5, and the combustion efficiency of the pellet can be improved.

Further, since the swirl flow is generated in the combustion dish 5 by the side wall hole 61, even if the ignition position is deviated from the center position during the combustion of the pellets, A high temperature can be maintained by concentrating the flame in the center.
In addition, as the combustion progresses, the pellets become ash. Similarly, the swirling flow through the side wall holes 61 and the blow-up from the lattice holes 60 float and stir the ash in the combustion dish 5, so that the ash containing tar content etc. It is possible to prevent the holes from adhering to and solidifying from the lattice holes 60 and the side wall holes 61 and the like.

Since the guide 51 extends upward surrounding the upper end opening of the combustion dish 5, it prevents the flame of the pellet from spreading laterally and licking the inner wall 41 of the combustion chamber, concentrating the flame in the center, and heat loss Can be reduced.
In particular, the grate 54 has a disk shape, the side wall 52 has a conical surface concentric with the grate 54, and the guide 51 has a cylindrical shape concentric with the grate 54. Smooth swirl flow can be obtained.

  A secondary air chamber 82 is formed outside the inner wall 41 of the combustion chamber 80, and a plurality of sets are provided in the circumferential direction of the inner wall 41 and a plurality of holes are arranged in the vertical direction. A swirl generated in the combustion dish 5 by blowing out the secondary air and changing the direction of the secondary air by a louver 45 provided along the hole row of the air hole set 47 and inclined with respect to the inner wall 41. Since the swirl flow is in the same direction as the flow, the unburned gas in the combustion chamber 80 can be concentrated and recombusted in the flame part of the pellet to be burned, and the heat exchange efficiency is improved by raising the combustion temperature. be able to.

  Further, the baffle 7 is provided at the upper portion of the combustion chamber 80 at a position facing the heat extraction hole 46 for discharging the combustion gas to the outside, so that the unburned gas is returned to the flame portion of the pellet to be burned again and completely. It can be made to burn and can raise a combustion temperature and can improve heat exchange efficiency.

In the embodiment, as the secondary air swirling and blowing means, the blowing direction of the secondary air blown from the air hole set 47 is changed using the louver 45 to generate a swirling flow in the combustion chamber 80. However, the inner wall 41 has a thick structure, and the direction of each hole of the air hole set is set to have an inclination angle of, for example, 45 ° with respect to a straight line toward the center of the combustion chamber 80. It is good also as a structure which produces | generates a swirl flow directly with the blown-out secondary air.
Moreover, although especially preferable angle values have been exemplified for the inclination angles α, β, γ, the present invention is not limited to the illustrated values, and any angle can be selected according to the situation.

  As in the embodiment, it is most preferable to obtain a smooth swirling flow of the primary air by making the grate of the combustion dish a disk, a side wall of a conical surface, and a guide of a cylindrical shape. Any or all of the grate, the side wall, and the guide may have a polygonal shape, and in this case, a considerably swirling flow can be obtained.

  Further, regarding the baffle 7, if the gap between the baffle 7 and the ceiling plate 43 can be adjusted by changing the length of the suspension member 71, the combustion discharged to the outside through the heat extraction hole 46. The gas flow can be controlled, and an optimal combustion state can be obtained even when the pellets have different combustion characteristics.

It is a longitudinal cross-sectional view which shows a pellet combustion apparatus. It is a figure which shows a combustion dish. It is a figure which shows the AA part cross section in FIG. It is a figure which shows the combustion state of a pellet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pellet combustion apparatus 2 Pellet supply apparatus 3 Blower 4 Outer case 5 Combustion dish 6 Ash tray 7 Baffle 10 Combustion apparatus main body 11 Bulkhead 20 Hopper 21 Supply passage 31A, 31B Blower pipe 41 Inner side wall 42 Outer side wall 43 Ceiling plate 44 Bottom plate 45 Louver 46 Heat extraction hole 47 Air hole set 51 Guide 52 Side wall 54 Grate 55 Partition wall 56 Introduction hole 60 Lattice hole 61 Side wall hole 71 Suspension member 80 Combustion chamber 81 Primary air chamber 82 Secondary air chamber 83 Air introduction chamber 100 Pellet

Claims (7)

In a pellet combustion apparatus for burning pellets in a combustion dish provided at the bottom of the combustion chamber,
The combustion dish is located at the center of the combustion chamber when viewed from above, and comprises a grate and a side wall that increases from the outer peripheral edge of the grate at a first inclination angle and widens the diameter as it goes upward.
The grate is provided with a plurality of lattice holes, and the side wall has a side wall hole oriented in a second inclination angle direction with respect to a straight line toward the center of the grate when the combustion dish is viewed from above. There are several,
A primary air is supplied from the primary air chamber formed on the lower side of the combustion dish through the lattice holes and the side wall holes into the combustion dish to generate a swirl flow in the combustion dish. A pellet combustion device.   The pellet combustion apparatus according to claim 1, wherein the first inclination angle is set to 45 to 65 °, and the second inclination angle is set to 45 °.   The pellet combustion apparatus according to claim 1, further comprising a guide extending upward surrounding the upper end opening of the combustion dish.   4. The grate according to claim 1, wherein the grate has a disc shape, the side wall has a conical surface concentric with the grate, and the guide has a cylindrical shape concentric with the grate. 2. The pellet combustion apparatus according to 1.   2. A secondary air swirling means for generating a swirling flow in the same direction as the swirling flow generated in the combustion dish is provided on a side wall of the combustion chamber in the combustion chamber. 5. The pellet combustion apparatus according to any one of 1 to 4. The secondary air swirl blowing means is
A plurality of air hole sets provided in the circumferential direction of the side wall of the combustion chamber and arranged in a predetermined number in the vertical direction;
A louver provided along the hole row of the air hole set and inclined with respect to the side wall of the combustion chamber;
The direction of the secondary air blown out from the secondary air chamber formed outside the side wall of the combustion chamber to the combustion chamber through the air hole set is changed in the swirl direction by the louver. 5. The pellet combustion apparatus according to 5.   The pellet combustion apparatus according to any one of claims 1 to 6, wherein a baffle is provided in an upper portion of the combustion chamber at a position facing a heat extraction hole for discharging combustion gas to the outside.

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