JP4816184B2 - Combustion device - Google Patents

Description

  The present invention relates to a combustion apparatus suitable for use when burning woody biomass fuel or the like and supplying it as a heat source such as a hot water boiler.

In recent years, solid woody biomass fuel that has been processed into chips or pellets instead of fossil fuels such as coal and oil is one of the measures to reduce carbon dioxide (CO ₂ ) to prevent global warming. The use of the combustion heat used has attracted attention.
According to the combustion apparatus using such woody biomass fuel, not only the amount of CO ₂ generated can be suppressed, but also the fuel itself is inexpensive, and thus there is an advantage that it is excellent in economic efficiency.

For example, Patent Document 1 below also discloses a combustion apparatus that supplies biomass, which is a coal substitute fuel, in an industrial boiler or the like into a furnace body and burns it.
Japanese Patent Laid-Open No. 2004-354031

  By the way, among the conventional combustion apparatuses using this kind of woody biomass fuel, in the fuel drop-in type, the fuel is generally supplied to the bottom of the combustion furnace, and formed in the rooster part that becomes the hearth. The fuel is combusted by ejecting combustion air from above and from the air holes formed on both side walls toward the upper and center of the combustion furnace.

  However, in the above-described conventional combustion apparatus, the unburned gas volatilized from the woody biomass fuel at the time of combustion and the flame and the combustion air are balanced depending on the air blown out from the air port of the rooster portion and the air holes on both side walls. There is a problem that carbon monoxide (CO) is not mixed well, and as a result, high concentration of carbon monoxide (CO) is discharged.

  In addition, when the above combustion device is used as a heat source for a boiler, combustion air that has not contributed to combustion cools the inside of a flue that is a heat exchanger in a furnace wall of a combustion furnace or a subsequent boiler. Therefore, it also contributed to lower boiler efficiency.

  The present invention has been made in view of such circumstances, and can efficiently mix unburned gas, flame and combustion air, and can increase the residence time of the combustion gas in the combustion furnace. It is an object of the present invention to provide a combustion apparatus that can greatly reduce the concentration of carbon monoxide in the inside and can increase the temperature in the furnace to improve the thermal efficiency.

In order to solve the above problems, the invention described in claim 1 is a cylindrical combustion furnace in which fuel is supplied to the bottom portion to form a combustion portion and an exhaust passage for combustion gas is provided at the top, Primary air supply means for supplying combustion primary air to the combustion section of the combustion furnace, a plurality of air ejection pipes standing at intervals along the inner wall of the combustion furnace, and combustion in these air ejection pipes Secondary air supply means for supplying secondary air, and the air ejection pipe has a top opening that is closed and a side wall that ejects the combustion secondary air in the circumferential direction of the combustion furnace. 1 air ejection holes and a second air ejection hole for ejecting the combustion secondary air toward the center of the combustion furnace are formed along the inner wall at the lower part of the combustion furnace. Annular fireproof surrounding the combustion part and supporting the air jet pipe It is characterized in that the wood is arranged.

Furthermore, the invention according to claim 2 is the invention according to claim 1, wherein the first ejection holes in the plurality of air ejection pipes are directed toward one side of the circumferential direction in the same direction. It is perforated so as to eject combustion secondary air.

The invention according to claim 3 is the invention according to claim 1 or 2 , wherein the combustion furnace is formed in a cylindrical shape, the number of the air ejection pipes is three or more, and the combustion is mutually performed. They are arranged at equal intervals in the circumferential direction of the furnace.

In the invention according to any one of claims 1 to 3 , in parallel with burning the fuel while supplying combustion primary air at the bottom of the combustion furnace and discharging the combustion gas from the upper exhaust flow path, When combustion secondary air is ejected from the air ejection pipe in the center direction and the circumferential direction of the fuel furnace, the combustion gas is swirled in the combustion furnace by the secondary combustion air ejected from the first air ejection hole. It rises toward the exhaust flow path while forming. The primary combustion air is preferably supplied upward from the bottom of the combustion furnace.

  As a result of the formation of the swirl flow, the residence time of the combustion gas in the combustion furnace is significantly increased as compared with the conventional combustion apparatus, and unburned gas, flame and combustion air are generated by the swirl flow. In addition to being efficiently mixed, the combustion of the unburned gas is promoted by the secondary combustion air ejected from the second air ejection holes. As a result, the concentration of carbon monoxide in the combustion gas discharged from the exhaust passage can be greatly reduced, and the furnace temperature can be increased to improve the thermal efficiency.

At this time, the lower part of the upper Symbol combustion furnace, in order to have arranged an annular refractory member surrounding the combustion portion along the inner wall, particularly when using wood biomass fuels solid as the fuel, the annular The fuel accumulation shape can be maintained by the refractory member, and the thermal efficiency can be improved by further maintaining the inside of the fuel furnace at a higher temperature by the heat storage of the refractory member.

In the invention according to claim 2 , since the first ejection holes directed in the circumferential direction of the plurality of air ejection pipes are formed so as to eject combustion secondary air in the same direction. In the combustion furnace, a stable swirling flow that is clockwise or counterclockwise in a plan view and spirals upward can be formed, and a second ejection hole can be formed in this. Is supplied to the center of the combustion furnace with sufficient combustion secondary air for combustion of unburned gas. The effect of reducing carbon oxide can be enhanced.

When the combustion furnace is formed in a cylindrical shape, as in the invention described in claim 3 , three or more air jet pipes are arranged at equal intervals in the circumferential direction of the combustion furnace. It is preferable to install. Further, the upper limit of the number of the air ejection pipes is appropriately selected according to the inner diameter of the combustion furnace, for example, when using the combustion apparatus according to the present invention as a heat source of a general hot water boiler, A preferable number of the air ejection pipes is in a range of 3 to 12.

1 to 5 show a best embodiment of a combustion apparatus according to the present invention and a hot water boiler integrally incorporated as a heat source, and reference numeral 1 in the drawing is a boiler.
This boiler 1 heats the water supplied from the water supply hole 35 by the combustion gas generated by burning solid fuel F obtained by processing wood into chips, and takes out the obtained hot water from the hot water supply hole 36. The combustion apparatus 2, the fuel supply apparatus 3 that supplies the solid fuel F to the combustion apparatus 2, and the heat exchanger 4 that generates hot water using the combustion gas discharged from the combustion apparatus 2. Is.

  Here, in the combustion apparatus 2, a cylindrical combustion furnace 6 with a ceiling portion closed is installed on a rectangular support plate 5 disposed at the bottom, and an air atmosphere is provided at the center of the support plate 5. A circular opening 7 is formed in communication with the lower part opened to the bottom. Further, a hollow box-like chamber for combustion secondary air 8 is provided on the lower surface side, and a plurality of (eight in the figure) sheath tubes 9 communicating with the inside of the chamber 8 are provided on the support plate 5. Are erected at equal intervals on the circumference along the outside of the opening 7. A secondary air fan 10 for sending combustion secondary air into the chamber 8 is attached to the lower side of the support plate 5.

  A cylindrical fuel introduction pipe 11 is disposed in the opening 7 of the support plate 5. The fuel introduction pipe 11 is formed to have a smaller diameter than the opening 7, whereby primary combustion air is introduced into the combustion furnace 6 from the lower side opened to the atmosphere between the fuel introduction pipe 11 and the opening 7. A flow path 12 for inflow is formed. The lower end portion of the fuel introduction pipe 11 is connected to the fuel supply device 3.

  As shown in FIG. 3, the fuel supply device 3 has a fuel pit 13 into which chip-shaped solid fuel is introduced, a lower end portion of the fuel pit 13 connected to one end portion, and a fuel introduction to the other end portion. A stalker box 14 having a stalker box 14 to which the lower end portion of the pipe 11 is connected, and a spiral blade that is rotatably provided in the stalker box 14 and feeds solid fuel supplied from the fuel pit 13 to the fuel introduction pipe 11 15 and a gear motor 16 that rotationally drives the rotating shaft 15 a of the stalker screw 15.

  On the other hand, a rectangular plate-shaped fixed grate 18 is attached to a rectangular recess 5 a formed on the upper surface of the support plate 5 with a rotating rod 17 interposed therebetween. Here, the rotating rod 17 protrudes from a ring portion 17a surrounding the outer periphery of the fuel introduction pipe 11, a pair of operating rods 17b extending radially outward from the ring portion 17a, and an upper surface of the operating rod 17b. The rotating pin 17c is integrally formed, and is provided to be rotatable around the outer periphery of the fuel introduction pipe 11.

  The fixed grate 18 is provided with an opening 18a and a hole 18b through which the fuel introduction pipe 11 and the sheath pipe 9 projecting from the support plate 5 are inserted, respectively, at the center and the outer periphery. In addition, between the openings 18a and the holes 18b, a plurality of (12 in the figure) substantially fan-shaped flow ports 18c communicating with the combustion primary air flow path 12 are equally spaced in the circumferential direction. In addition, the rotating pin 17c of the rotating rod 17 is inserted and a short arc-shaped groove portion 18d that allows the rotating rod 17 to rotate in a predetermined angle range is formed. Has been.

  A rotating grate 20 is disposed on the fixed grate 18. The rotary grate 20 is formed with an opening 20a having an inner diameter substantially equal to that of the fuel introduction pipe 11 at the center, and a plurality (in the drawing, in communication with the circulation port 18c of the fixed grate 18 around the opening 20a. 12), a substantially fan-shaped distribution port 20b. In addition, at two locations on the outer periphery, cutout portions 20 c are formed that engage with the rotation pins 17 c of the rotation rod 17 protruding from the groove portions 18 d of the fixed grate 18.

  As a result, the rotating rod 20 is rotated by the operating rod 17b within the length range of the groove portion 18d of the fixed grate 18 and the rotating grate 20 is rotated integrally, whereby the circulation port 18c and the rotating grate are rotated. The communication area with the 20 circulation ports 20b, that is, the inflow amount of the combustion primary air can be adjusted.

  On the fixed grate 18, a refractory member formed in a cylindrical shape as a whole by a plurality (eight in the figure) of refractory bricks 21 is disposed along the inner wall of the combustion furnace 6. Here, a U-shaped recess 21a penetrating in the vertical direction is formed on the outer peripheral surface of each refractory brick 21, and an air ejection pipe 22 is inserted into the recess 21a. The air ejection pipe 22 is a cylindrical member whose upper end is closed, and a lower end opening is inserted into the sheath pipe 9 erected on the support plate 5.

  As a result, the air ejection pipe 22 is supported by the refractory brick 21 at equal intervals in the circumferential direction along the inner wall of the combustion furnace 6, and the inside is communicated with the chamber 8 for combustion secondary air. Yes. And in the side wall which protrudes from the refractory brick 21 of each air ejection pipe 22, the 1st air ejection hole 23 which ejects combustion secondary air in one direction of the circumferential direction of the combustion furnace 6, and the combustion furnace 6 Second air ejection holes 24 for ejecting combustion secondary air toward the center are formed at a plurality of locations (two locations in the figure) spaced apart in the vertical direction.

  As a result, combustion secondary air is supplied into the combustion furnace 6 by the secondary air fan 10, the chamber 8, the sheath tube 9, the air ejection tube 22, the first air ejection hole 23, and the second air ejection hole 24. Secondary air supply means is configured.

  On the other hand, an exhaust port 25 for exhausting combustion gas generated in the combustion furnace 6 is formed in the upper side wall of the combustion furnace 6. Here, the exhaust ports 25 are formed at two locations spaced in the circumferential direction of the combustion furnace 6, and further, the upper part communicates with each exhaust port 25 on the outer wall of the combustion furnace 6, and the lower part is Two ducts 26 communicating with the lower part of the adjacent heat exchanger 4 are formed.

  The heat exchanger 4 is a rectangular box-shaped member disposed adjacent to the combustion furnace 6, and the internal space is vertically divided by the upper partition plate 4 a and the lower partition plate 4 b in the lower combustion gas chamber 27 and the water chamber 28. The upper combustion gas chamber 29 is partitioned into three chambers. Further, the lower combustion gas chamber 27 is divided into an upstream side 27 a and a downstream side 27 b by a partition wall 30.

  Between the upper partition plate 4a and the lower partition plate 4b, there are a large number of smoke tubes 31 (11 × 4 rows = 44 in total in the figure) that allow the lower combustion gas chamber 27 and the upper combustion gas chamber 29 to communicate with each other. Is provided. Here, the 11 × 2 rows of the smoke tubes 31 are arranged between the upstream side 27a of the lower combustion gas chamber 27 and the upper combustion gas chamber 29, and the other 11 × 2 rows of the smoke tubes 31 are arranged on the upper side. It is arranged between the combustion gas chamber 29 and the downstream side 27 b of the lower combustion gas chamber 27.

  As a result, the exhaust port 25 leads to the upstream side 27a of the lower combustion gas chamber 27 through the duct 26, and further from the upper combustion gas chamber 29 through the 22 smoke tubes 31, and again through the other 22 smoke tubes 31. A fuel gas exhaust passage reaching the downstream side 27b of the chamber 27 is formed. A lower end portion of an external exhaust pipe 32 for exhausting the combustion gas is connected to the downstream side 27b of the lower combustion gas chamber 27.

The external exhaust pipe 32 exhausts the combustion gas in the combustion furnace 6 through the exhaust passage and holds the combustion furnace 6 at a negative pressure, while combusting primary air from the passage 12 to the inside. Is provided with an exhaust gas fan (primary air supply means) 33.
In the figure, reference numeral 34 denotes an automatic ignition device for igniting the solid fuel F made of chip-shaped wood supplied from the fuel introduction pipe 11 to the bottom of the combustion furnace 6 by the fuel supply device 3.

  In the hot water boiler 1 incorporating the combustion device 2 having the above-described configuration, solid fuel F obtained by processing wood into chips is put into the fuel pit 13 of the fuel supply device 3, and the stalker screw 15 is rotated by the gear motor 16. As a result, the inside of the stalker box 14 is transferred and supplied into the fuel introduction pipe 11. Then, the solid fuel F sent into the fuel introduction pipe 11 is deposited on the rotary grate 20 at the bottom of the combustion furnace 6 surrounded by the refractory bricks 21.

  In parallel with this, air in the combustion furnace 6 is sucked by the exhaust gas fan 33 and the combustion primary air flows from the flow path 12 of the opening 7 to the fixed grate 18 while keeping the inside at a negative pressure. From the bottom of the combustion furnace 6 through the space between the port 18c and the circulation port 20b of the rotary grate 20, it is caused to flow upward as indicated by the dotted line arrow in the figure. Next, the automatic ignition device 34 is operated to ignite the solid fuel F and burn it, thereby forming a combustion portion at the bottom of the combustion furnace 6.

  Further, combustion secondary air is sent into the chamber 8 by the secondary air fan 10, and the first air ejection hole 23 and the second air ejection hole 24 of the air ejection pipe 22 are shown by solid arrows in the figure. From the center of the fuel furnace 6 and one direction in the circumferential direction. Then, the combustion gas is produced by the combustion primary air supplied upward from the bottom of the combustion furnace 6 and the combustion secondary air ejected from the first air ejection holes 23 in the circumferential direction of the combustion furnace 6. Combustion secondary that rises while forming a swirl flow in the interior, and in which unburned gas, flame, and combustion air are efficiently mixed, and is further ejected from the second ejection hole 24 toward the center. Air promotes combustion of unburned gas.

  Then, the combustion gas that has reached the upper part of the fuel furnace 6 is exhausted from the exhaust port 25 to the duct 26. Next, the combustion gas in the duct 26 flows into the upstream side 27 a of the lower combustion gas chamber 27 by the exhaust gas fan 33 and is sent to the upper combustion gas chamber 29 through the 22 smoke pipes 31. It flows to the downstream side 27b of the lower combustion gas chamber 27 through the main smoke pipe 31, and is exhausted from the external exhaust pipe 32 to the outside. At this time, in the smoke pipe 31, heat is exchanged with the water in the water chamber 28 supplied from the water supply hole 35 to make the water warm. The hot water obtained in the water chamber 28 is discharged from the hot water supply hole 36 for use.

  As described above, according to the combustion apparatus 2 configured as described above, the solid fuel F is burned while supplying the combustion primary air from the bottom of the combustion furnace 6 upward, and the combustion gas is discharged to the upper portion by the exhaust gas fan 33. In parallel with discharging from the exhaust port 25, the combustion gas is swirled in the combustion furnace 6 by ejecting the combustion secondary air from the air ejection pipe 22 toward the center direction and the circumferential direction of the fuel furnace 6. Therefore, the residence time of the combustion gas in the combustion furnace 6 is significantly increased, so that unburned gas, flame and combustion air can be mixed efficiently.

  In addition, since the combustion secondary air sufficient for the combustion of the unburned gas is supplied from the second ejection hole 24 of the air ejection pipe 22 toward the center of the combustion furnace 6, the above-described combustion secondary air is used. Combustion of unburned gas is promoted. As a result, the carbon monoxide concentration in the combustion gas finally discharged from the external exhaust pipe 32 can be greatly reduced as compared with the conventional one, and the temperature inside the furnace is increased to improve the thermal efficiency. It can also be made.

  At this time, since the fire-resistant member configured in a cylindrical shape by the plurality of fire-resistant bricks 21 surrounding the combustion portion along the inner wall is disposed in the lower portion of the combustion furnace 6, the cylindrical fire-resistant member is used. The solid fuel F can be kept in a deposited shape, and the heat efficiency of the fuel furnace 6 can be further increased by the heat storage of the refractory member to improve the thermal efficiency.

  Incidentally, in the conventional combustion apparatus for burning the solid fuel, the carbon monoxide (CO) concentration in the combustion gas was about 2000 ppm, whereas the boiler having the above-described configuration was operated, and the external exhaust pipe When the carbon monoxide (CO) concentration in the combustion gas discharged from No. 32 was detected, it was confirmed that the concentration was greatly reduced to 50 ppm or less. At the same time, the temperature in the combustion furnace 6 is increased from about 600 ° C. to 680 ° C., and the temperature of the combustion gas is increased from about 160 ° C. to 170 ° C. It was also confirmed that it was improved to 90%.

In addition, in the said embodiment, although demonstrated only about the case where the combustion apparatus which concerns on this invention was integrated in the boiler 1, it is not restricted to this, It is possible to apply as a combustion apparatus of various apparatuses. . Further, the shape of the fuel furnace 6 is not limited to a cylindrical shape, and the same effect can be obtained even when the shape is a rectangular tube shape.
The height dimension and the number of the air ejection pipes 22 and the number of the first and second air ejection holes 23 and 24 formed in the air ejection pipe 22 are also the same as those of the combustion furnace 6. However, the present invention is not limited to the above embodiment.

  Further, the drilling position of the first and second air ejection holes 23 and 24 is not limited to the upper side of the refractory brick 21, for example, is drilled at the base of the refractory brick 21, and the above-mentioned swirl flow is generated from the root portion of the flame. By doing so, the secondary combustion of the unburned gas may be further promoted, and the shapes of the first and second air ejection holes 23 and 24 are not limited to the circular shape, and the turning performance can be improved. Various shapes can be selected.

It is a longitudinal section showing a hot water boiler incorporating one embodiment of a combustion device concerning the present invention. It is a cross-sectional view of FIG. It is a sectional side view of the lower part in the combustion apparatus of FIG. It is a perspective view which shows the inside of the lower combustion furnace in the combustion apparatus of FIG. FIG. 5 is an exploded perspective view of FIG. 4.

Explanation of symbols

2 Combustion device 3 Fuel supply device 6 Combustion furnace 10 Secondary air fan 20 Rotating grate 21 Refractory brick (refractory member)
22 Air ejection pipe 23 1st air ejection hole 24 2nd air ejection hole 25 Exhaust port 33 Exhaust gas fan (primary air supply means)
F Solid fuel

Claims (3)

A cylindrical combustion furnace in which fuel is supplied to the bottom part to form a combustion part and a combustion gas exhaust passage is provided in the upper part, and primary air supply for supplying combustion primary air to the combustion part of the combustion furnace Means, a plurality of air ejection pipes standing at intervals along the inner wall of the combustion furnace, and secondary air supply means for supplying combustion secondary air into these air ejection pipes,
The air jet pipe is closed at the top opening, and on the side wall, the first air jet hole for jetting the combustion secondary air in the circumferential direction of the combustion furnace, and the center toward the combustion furnace A second air ejection hole for ejecting combustion secondary air is provided , and an annular ring is formed in the lower part of the combustion furnace so as to surround the combustion portion along the inner wall and to support the air ejection pipe. A combustion apparatus comprising a refractory member . The first ejection holes in the plurality of air ejection pipes are formed so as to eject the combustion secondary air toward one side of the circumferential direction which is the same direction as each other. Item 4. The combustion apparatus according to Item 1. The combustion furnace is formed in a cylindrical shape, and the number of the air ejection pipes is three or more, and they are arranged at equal intervals in the circumferential direction of the combustion furnace. Item 3. The combustion apparatus according to Item 1 or 2.

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