JP5336876B2 - Biofuel combustion equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably and efficiently burn biofuel in small shape such as sawdust or rice hull without generation of clinker. <P>SOLUTION: The biofuel combustion device 1 includes: a combustion part 2 which blows combustion air a including pneumatically conveyable biofuel f into a combustion chamber S to cyclone-burn the fuel; an annular inside water-cooled wall 3 disposed on the outlet side of the combustion chamber S to form a secondary combustion chamber S' communicating with the combustion chamber S; an annular water-cooled wall 4 disposed outside the inside water-cooled wall 3 to form an annular combustion gas passage 15 communicating with the secondary combustion chamber S' and a flue 12 with the inside water-cooled wall 3; and an upper header 6 and a lower header 7 connected to both the water-cooled walls 3 and 4. The biofuel f and combustion air a blown into the chamber S through an injection nozzle 9 are cyclone-burnt in the combustion chamber S, and the resulting ash is caused to flow with combustion gas G, and discharged from the combustion chamber S to the flue 12 through the secondary combustion chamber S' and the combustion gas passage 5. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a combustion apparatus that burns biofuel as fuel, and in particular, biofuel having a relatively small shape capable of pneumatic transportation such as sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, etc. The present invention relates to a biofuel combustion apparatus that burns fuel as fuel.

  In general, sawdust discharged from a sawmill and rice husk discharged from a rice mill are put into a combustion chamber of a large waste incinerator together with waste such as municipal waste at a waste incineration facility. Or landfilled with waste.

  By the way, in recent years, the use of biomass as a fuel has been actively promoted from the viewpoint of diversifying energy supply sources and de-oiling. For example, the present applicant has developed a steam boiler (see Patent Document 1) and a combustion furnace (see Patent Document 2) in which wood pellets made from wood biomass such as waste wood and remaining wood are burned as fuel.

  However, steam boilers and combustion furnaces that use wood pellets as fuel have been developed to burn relatively large solid fuels such as wood pellets that are stable in quality such as shape and moisture content. There is a problem that even when a biofuel having a small shape such as sawdust or rice husk is put into the combustion chamber as it is, it cannot be burned well.

  On the other hand, as a method of burning a biofuel having a small shape such as sawdust or rice husk without processing into a pellet, it is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-132567 (see Patent Document 3). In addition, a combustion apparatus for biomass fuel disclosed in Japanese Laid-Open Patent Publication No. 2008-286451 (see Patent Document 4) is known.

However, in the former combustion furnace, the airflow is spirally swirled along the inner peripheral surface of the combustion chamber having a circular cross section formed in the furnace body, and in this state, sawdust and rice husk are supplied into the combustion chamber and burned. However, since the sawdust and rice husk are fed from the powder burner provided at the center of the front wall of the furnace body to the center of the combustion chamber by air injection toward the axial direction. However, some of the sawdust and rice husk may be discharged from the combustion chamber without being burned without being involved in the swirling flow, and there is a problem that combustion of the sawdust and rice husk cannot be performed reliably and satisfactorily.
However, in this combustion furnace, the entire furnace interior is covered with refractory, so the heat is stored in the refractory and the furnace temperature rises, and some of the ash melts and clinker is in the furnace. There is a problem that occurs.

  Further, the latter biomass fuel combustion device supplies combustion air from the inner peripheral wall of the combustion chamber in a swirl flow, and even in this state, biomass fuel such as rice husk is supplied in a powder state to the combustion chamber. Although it is made to burn, it is formed in the combustion chamber because biomass fuel is supplied in the radial direction into the combustion chamber by the wind of the fuel input fan from the fuel supply pipe provided on the side wall of the combustion furnace. The swirl flow is disturbed, and there is a problem that good cyclone combustion cannot be performed.

JP 2008-064370 A Registered Utility Model No. 3099224 JP 2004-132567 A JP 2008-286451 A

  The present invention has been made in view of such problems, and its purpose is to produce a biofuel having a small shape that can be pneumatically transported, such as sawdust and rice husk, without generating a clinker. An object of the present invention is to provide a biofuel combustion apparatus that can stably and efficiently burn, and that can recover thermal energy generated by combustion as steam, hot water, or hot air.

In order to achieve the above object, the invention according to claim 1 of the present invention is capable of pneumatic transportation like sawdust, rice husk, finely crushed wood chips, finely crushed bagasse from a nozzle blown into a combustion chamber having a circular cross section. Combustion air mixed with fresh biofuel is blown in the tangential direction of the circumferential surface of the combustion chamber to form a cyclone flow. The biofuel is combusted in the cyclone flow, and the generated ash flows together with the combustion gas to create a combustion chamber. A combustion section that discharges from the combustion chamber, an annular water cooling wall that is disposed on the combustion chamber outlet side of the combustion section and that forms a secondary combustion chamber having a circular cross section that communicates with the combustion chamber inward, and an outer water cooling wall An annular outer water cooling wall disposed in the opposite position, an annular combustion gas passage formed between the inner water cooling wall and the outer water cooling wall and communicating with the secondary combustion chamber and the flue, and both water cooling walls The upper part connected to each other And a lower header, the biofuel injected from the blowing nozzle into the combustion air is subjected to cyclone combustion in the combustion chamber, and the generated ash is flowed together with the combustion gas from the combustion chamber to the secondary combustion chamber and A biofuel combustion apparatus for discharging to a flue through a combustion gas passage, wherein the combustion section is provided on a cylindrical peripheral wall, an end wall closing one end opening of the peripheral wall, and an opening on the other end of the peripheral wall Combustion body that has an annular orifice wall that forms an orifice hole, forms a combustion chamber with a circular cross-section with the outlet wall constricted inside by the orifice wall, and penetrates the peripheral wall near the orifice wall of the combustion body Provided in the combustion chamber body, and a blowing nozzle for blowing combustion air mixed with biofuel capable of pneumatic transportation into the combustion chamber in a tangential direction of the peripheral surface of the combustion chamber. It is equipped with an ignition burner that ignites biofuel blown together with combustion air from the blow nozzle into the combustion chamber, and the opening area of the orifice hole is mixed with the biofuel blown into the combustion chamber from the blow nozzle The combustion air is set to be 1/2 or more of the cross-sectional area of the combustion chamber so that the combustion air does not flow into the secondary combustion chamber through the orifice hole immediately from the combustion chamber, and the distance between the blowing nozzle and the orifice wall is set from the blowing nozzle. The combustion air mixed with the biofuel injected into the combustion chamber is set to be 2 to 3 times the inner diameter of the injection nozzle so that it does not flow from the combustion chamber immediately into the secondary combustion chamber via the orifice hole. There is a feature.

The invention of claim 2 of the present invention is for combustion in which biofuel that can be transported by air such as sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, etc. is injected from a nozzle into a combustion chamber having a circular cross section. A combustion section that blows air in the tangential direction of the circumferential surface of the combustion chamber to form a cyclone flow, burns biofuel in the cyclone flow, flows the generated ash together with the combustion gas, and discharges it from the combustion chamber, and combustion An annular hot-blast furnace wall of an air- cooled jacket structure, which is arranged on the outlet side of the combustion chamber of the section and which is formed of an inner steel plate and an outer steel plate that form a secondary combustion chamber having a circular cross section communicating inward with the combustion chamber and the flue The biofuel injected into the combustion air from the blowing nozzle is subjected to cyclone combustion in the combustion chamber, and the generated ash is flowed together with the combustion gas to perform secondary combustion from the combustion chamber. The biofuel combustion apparatus is configured to discharge into a flue through the combustion section, and a combustion chamber having a circular cross section is formed inwardly of a cylindrical peripheral wall and an end wall closing one end opening of the peripheral wall. The combustion part main body and a blow nozzle that is provided in a penetrating manner in the peripheral wall near the end wall of the combustion part main body and blows combustion air mixed with biofuel capable of air transportation into the combustion chamber in the tangential direction of the peripheral surface of the combustion chamber And an ignition burner for igniting the biofuel blown together with the combustion air from the blow nozzle into the combustion chamber, and an inner steel plate forming the annular hot stove wall In addition, a nozzle hole for injecting cooling air into the secondary combustion chamber is formed, and at the downstream end of the annular hot-blast furnace wall, dilution air is injected into the outlet side of the secondary combustion chamber to form the secondary combustion chamber. Gas temperature discharged from the combustion chamber It is characterized by providing the diluted air supply mechanism for adjusting.

According to a third aspect of the present invention, the peripheral wall and the orifice wall of the combustion section main body are formed as a water cooling wall having a water cooling jacket structure made of a steel plate to cool the combustion chamber, and blow into the heat transfer area of the combustion chamber and the combustion chamber. It is characterized in that the air ratio of the combustion air is set to 1.40 to 1.90 so that the combustion temperature in the combustion chamber is not higher than the melting point of ash .

According to a fourth aspect of the present invention, the peripheral wall of the combustion section main body is formed as an air cooling wall having an air cooling jacket structure made of a steel plate to cool the combustion chamber, and the heat transfer area of the combustion chamber and the combustion air blown into the combustion chamber The air ratio is set to 1.40 to 1.90 where the combustion temperature in the combustion chamber is equal to or lower than the melting point of ash .

The invention of claim 5 of the present invention is characterized in that the combustion air mixed with biofuel is blown into the combustion chamber from the blowing nozzle at a flow velocity of 10 m / s or more .

According to a sixth aspect of the present invention, a blowing nozzle is arranged in parallel with the circumferential wall of the combustion section main body in the circumferential direction of the combustion chamber, and combustion air mixed with biofuel from each blowing nozzle is placed in the combustion chamber. It is characterized by blowing in the tangential direction of the peripheral surface .

The biofuel combustion apparatus according to claims 1 to 6 of the present invention can exhibit the following excellent effects.
(1) That is, the biofuel combustion apparatus according to claim 1 and claim 2 of the present invention introduces combustion air mixed with biofuel that can be blown into a combustion chamber having a circular cross section and can be transported by air from a nozzle into the combustion chamber. The cyclone flow is formed by blowing in the tangential direction of the surface, the biofuel is cyclone burned in the cyclone flow, and the generated ash flows with the combustion gas and is discharged from the combustion chamber. The clinker can be prevented from being produced.
(2) In the biofuel combustion apparatus according to claims 1 and 2 of the present invention, the biofuel blown together with the combustion air from the blow nozzle into the combustion chamber burns while performing a cyclonic motion. Stirring and mixing of biofuel and combustion air, which are important elements, are promoted, and the residence time of the biofuel in the combustion chamber is increased, so that the biofuel can be stably and efficiently burned.
(3) Since the biofuel combustion apparatus according to claim 1 and claim 2 of the present invention causes the biofuel to be subjected to cyclone combustion in the combustion chamber, combustion is performed even if the axial length of the combustion chamber is shortened. It can be completed and the combustion chamber can be made compact.
In particular, the biofuel combustion apparatus according to claim 1 of the present invention is provided with an orifice wall at the outlet-side opening of the combustion chamber, and an injection nozzle is provided on the peripheral wall near the orifice wall of the combustion section body. Since the generated cyclone flow descends in the combustion chamber toward the end wall and then moves up in the combustion chamber, the axial length of the combustion chamber can be shortened, and the combustion chamber can be made more compact. .
(4) In the biofuel combustion apparatus according to claims 1 and 2 of the present invention, since the biofuel is subjected to cyclone combustion in the combustion chamber, it is burned in the center of the combustion chamber by the cyclone flow of the combustion gas. A gas recirculation region is formed, and generation of NOx can be suppressed.
(5) The biofuel combustion apparatus according to claim 1 and claim 2 of the present invention blows and burns combustion air mixed with biofuel capable of air transportation into the combustion chamber from the blow nozzle. Therefore, those having a relatively small shape such as sawdust, rice husk, finely crushed wood chips and the like can be effectively used as fuel.
(6) The biofuel combustion apparatus according to claim 3 and claim 4 of the present invention is a water-cooled wall having a water-cooled jacket structure or an air-cooled jacket-structured air-cooled jacket structure in which at least a peripheral wall portion provided with a blowing nozzle of the combustion section body is made of a steel plate Because it is configured as a wall to cool the combustion chamber, the heat transfer area of the combustion chamber and the air ratio of the combustion air blown into the combustion chamber are set so that the combustion temperature in the combustion chamber is lower than the melting point of ash The ash in the combustion chamber does not melt and adhere to the combustion chamber, and the production of clinker can be more reliably prevented.
(7) In the biofuel combustion apparatus according to claim 3 and claim 4 of the present invention, the peripheral wall portion of the combustion section main body provided with the blowing nozzle is formed of a steel plate, so that it was blown from the blowing nozzle at a high speed. Wear of the peripheral wall portion due to biofuel can be prevented.
(8) In the biofuel combustion apparatus according to claim 5 of the present invention, combustion air mixed with biofuel is blown into the combustion chamber from the blow nozzle at a speed of 10 m / s or more. In this case, the cyclone combustion is performed well and reliably.
(9) In the biofuel combustion apparatus according to claim 6 of the present invention, combustion nozzles are provided with injection nozzles arranged in parallel in the circumferential direction of the combustion chamber on the peripheral wall of the combustion section body, and biofuel is mixed from each injection nozzle. Since air is blown into the combustion chamber in the tangential direction of its inner peripheral surface, a stronger cyclone flow is formed in the combustion chamber, and stirring and mixing of biofuel and combustion air are further promoted. In addition, the flame can be shortened.

1 is a longitudinal sectional view of a biofuel combustion apparatus according to a first embodiment of the present invention. It is a cross-sectional view of the biofuel combustion apparatus shown in FIG. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a longitudinal cross-sectional view of the biofuel combustion apparatus which concerns on the 2nd Embodiment of this invention. It is the EE sectional view taken on the line of FIG. It is the FF sectional view taken on the line of FIG. It is the GG sectional view taken on the line of FIG. It is a cross-sectional view which shows the principal part of the biofuel combustion apparatus which concerns on the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 4 show a biofuel combustion apparatus 1 according to a first embodiment of the present invention. The biofuel combustion apparatus 1 blows into a combustion chamber S (primary combustion chamber S) having a circular cross section. Combustion air a mixed with biofuel f (for example, sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, finely crushed corn straw, etc.) that can be pneumatically conveyed from the nozzle 9 is contained in the combustion chamber S. A combustion section 2 that blows in the tangential direction of the peripheral surface to form a cyclone flow, burns the biofuel f in the cyclone flow, causes the generated ash to flow with the combustion gas G, and discharges it from the combustion chamber S; An annular inner water cooling wall 3 which is disposed on the outlet side of the combustion chamber S of the section 2 and forms a secondary combustion chamber S ′ having a circular cross section communicating with the combustion chamber S of the combustion section 2 inward, and an inner water cooling wall 3 water cooling outside the ring arranged at the outer position 4, an annular combustion gas passage 5 formed between the inner water cooling wall 3 and the outer water cooling wall 4 and communicating with the secondary combustion chamber S 'and the flue 12, and both water cooling walls 3 and 4, respectively. A small-capacity steam boiler (through-flow boiler) having an upper header 6 and a lower header 7 connected in communication is formed, and biofuel f mixed with the combustion air a from the injection nozzle 9 is injected. Cyclone combustion is performed in the combustion chamber S of the combustion section 2, and the generated ash flows together with the combustion gas G and is discharged from the combustion chamber S to the flue 12 through the secondary combustion chamber S ′ and the combustion gas passage 5. It is.

  In the biofuel combustion apparatus 1 having the steam boiler structure, the heat absorption into the boiler water flowing in the inner water cooling wall 3 is mainly caused by the radiant heat transfer by the generated combustion gas G and the secondary combustion chamber. Boiler water which is performed by contact heat transfer (convection heat transfer) by the combustion gas G flowing in S ′ and contact heat transfer by the combustion gas G flowing in the combustion gas passage 5 and flowing in the outer water cooling wall 4. The heat absorption is performed only by contact heat transfer by the combustion gas G flowing in the combustion gas passage 5.

  1, 3, and 4, the combustion section 2 includes a cylindrical peripheral wall 8 a, an end wall 8 b that closes one end opening (lower end opening) of the peripheral wall 8 a, and the other end opening of the peripheral wall 8 a ( Combustion chamber S (primary combustion chamber S) having a circular cross section, which is formed of an annular orifice wall 8c provided in the upper end opening) to form an orifice hole 8c 'and whose outlet side is restricted by the orifice wall 8c. Combustion air a containing biofuel f, which is provided in a penetrating manner in the combustion body main body 8 and the peripheral wall 8a near the orifice wall 8c of the combustion body 8, and is capable of transporting air into the combustion chamber S, is formed in the combustion chamber S. An injecting nozzle 9 that blows in the tangential direction of the inner peripheral surface, and an ignition that is provided on the peripheral wall 8a of the combustion section main body 8 and ignites the biofuel f that is injected from the injecting nozzle 9 into the combustion chamber S together with the combustion air a. And a burner 10 for use.

As shown in FIGS. 1 and 3, the peripheral wall 8a and the orifice wall 8c of the combustion section main body 8 are formed as a water-cooled wall having a water-cooled jacket structure with a steel plate having excellent heat resistance. Thus, the inside of the combustion chamber S is cooled. The cooling water w preheated through the water cooling jacket 8d is used as boiler water supply.
Further, as shown in FIG. 1, the end wall 8b of the combustor body 8 is formed as a fire wall having a concave cross section by a refractory material such as a castable refractory or a fire refractory. A water-cooling jacket 8e through which the cooling water w flows is formed of a steel plate excellent in the above. The water cooling jacket 8e on the end wall 8b is in communication with the water cooling jacket 8d on the peripheral wall 8a.
Further, as shown in FIG. 4, an opening 8f for inspection / cleaning is formed at the rising portion of the end wall 8b of the combustion section main body 8, and a cover 8g for inspection / cleaning is attached to the opening 8f. It has been.

Note that the heat transfer area of the combustion chamber S (including the cooling area of the peripheral wall 8a of the water-cooled wall structure) depends on the air ratio of the combustion air a blown into the combustion chamber S from a blow nozzle 9 described later. The internal combustion temperature is set to be equal to or lower than the melting point of ash.
The opening area of the orifice hole 8c ′ (the area of the cross section) is such that the combustion air a mixed with the biofuel f blown into the combustion chamber S from the blowing nozzle 9 immediately passes through the orifice hole 8c ′ from the combustion chamber S. Thus, it is set so as not to flow into the secondary combustion chamber S ′. In this embodiment, the opening area of the orifice hole 8 c ′ is set to ½ or more of the transverse area of the combustion chamber S.

As shown in FIGS. 1 and 3, the blowing nozzle 9 is provided in a penetrating manner in the peripheral wall 8 a near the orifice wall 8 c of the combustion section main body 8, and has a light and small shape capable of pneumatic transportation into the combustion chamber S. Combustion air a mixed with biofuel f is blown in the tangential direction along the inner peripheral surface of the combustion chamber S from a nozzle port 9 a that opens to the combustion chamber S.
That is, the blowing nozzle 9 can smoothly flow the combustion air a mixed with a small-shaped biofuel f that can be pneumatically transported, such as sawdust and rice husk, without causing a slow speed portion or a stagnation portion. The cross-sectional shape is constituted by a metal pipe having a circular shape, and is spaced from the peripheral wall 8a of the combustion section main body 8 along the tangential direction of the inner peripheral surface of the combustion chamber S by a predetermined distance from the orifice wall 8c to the end wall 8b side. It is provided in a penetrating manner at the position.
A small-shaped biofuel f such as sawdust and rice husk is transported to the blowing nozzle 9 by pneumatic transportation, and the air used for pneumatic transportation is supplied to the blowing nozzle 9 together with the biofuel f as combustion air a. A fuel / air supply pipe 11 is connected.

The distance between the blowing nozzle 9 and the orifice wall 8c (the distance between the axis of the blowing nozzle 9 and the lower end surface of the orifice wall 8c) is mixed with the biofuel f blown from the blowing nozzle 9 into the combustion chamber S. It is preferable that the combustion air a is set according to the inner diameter d of the blowing nozzle 9 so that the combustion air a does not immediately flow from the combustion chamber S through the orifice hole 8c ′ into the secondary combustion chamber S ′. Specifically, it is preferable to set the distance between the blowing nozzle 9 and the orifice wall 8 c to be 2 to 3 times the inner diameter d of the blowing nozzle 9.
Moreover, it is preferable to set the ejection speed of the combustion air a mixed with the biofuel f from the blowing nozzle 9 to 10 m / s or more in order to effectively perform cyclone combustion.
For example, in the biofuel combustion apparatus 1 shown in FIGS. 1 to 4, if the combustion control is three-position control (stop, low combustion, high combustion) by steam pressure, at the rated time (high combustion). The jet speed of the combustion air a mixed with the biofuel f from the blow nozzle 9 is preferably set to 20 m / s to 40 m / s, and the combustion air from the blow nozzle 9 at the time of low combustion The ejection speed of a is set so as to be 10 m / s to 20 m / s so that the combustion amount at the time of low combustion becomes 1/2 of the combustion amount at the time of high combustion.
Further, the air ratio of the combustion air a blown into the combustion chamber S from the blow nozzle 9 is set so that the combustion temperature in the combustion chamber S is lower than the melting point of ash, depending on the heat transfer area of the combustion chamber S. It is preferable to keep it. Specifically, the supply amount of the combustion air a blown into the combustion chamber S from the blow nozzle 9 is preferably set to 1.40 to 1.90 in air ratio.
The inner diameter d of the blowing nozzle 9 is preferably set in accordance with the inner diameter D of the combustion chamber S in order to effectively perform cyclone combustion. Specifically, the inner diameter d of the blowing nozzle 9 and the inner diameter D of the combustion chamber S are preferably set to D / d> 5-8.

As shown in FIGS. 1 and 4, the ignition burner 10 is provided on the downstream side in the ejection direction of the blowing nozzle 9 and in a penetrating manner in the peripheral wall 8 a of the combustion section main body 8. The biofuel f blown together with the combustion air a is ignited.
That is, the ignition burner 10 is in a posture along the tangential direction of the inner peripheral surface of the combustion chamber S at the rising portion of the end wall 8b having a concave cross-sectional shape and the combustion air a mixed with the biofuel f from the blowing nozzle 9 An ignition nozzle 10a made of a metal having a circular cross section provided in a position where the combustion gas G 'can be mixed with the flow of the gas, a fuel injection nozzle 10b disposed at an axial position in the ignition nozzle 10a, and a fuel injection nozzle Combustion gas G ′ generated by the combustion of fuel is blown from the nozzle opening 10a ′ of the ignition nozzle 10a in the same direction as the blowing direction of the nozzle 9 and combusted. It can be ejected in the tangential direction along the inner peripheral surface of the chamber S.
Although not shown, the ignition burner 10 is provided with a flame detector at a position where the flame of the ignition burner 10 and the combustion flame caused by the combustion of the biofuel f can be detected . Detected.

As shown in FIGS. 1 and 2, the inner water cooling wall 3 is a band plate in which a plurality of water pipes 3 a (thick bare pipes) made of steel plates are arranged in parallel in an annular shape and the adjacent water pipes 3 a extend in the vertical direction. It is formed by connecting with the shape fin 3b, and the cross-sectional shape is formed in a circular airtight structure. The inner water cooling wall 3 is disposed above the combustion unit body 8 and on the axis of the combustion unit body 8, and the space surrounded by the water cooling wall 3 communicates with the combustion chamber S of the combustion unit body 8. The secondary combustion chamber S ′ has a circular cross section.
In addition, a plurality of combustion gases that cause the combustion gas G in the secondary combustion chamber S ′ to flow into the annular combustion gas passage 5 by notching the upper end portions of the plurality of fins 3 b at the upper part of the inner water cooling wall 3. A passage port 3c is formed.

As shown in FIGS. 1 and 2, the outer water cooling wall 4 is composed of a plurality of steel plate water pipes 4 a (thick bare pipes) arranged in parallel in an annular manner as in the case of the inner water cooling wall 3. It is formed by connecting 4a with strip-like fins 4b extending in the up-down direction, and is formed in an airtight structure with a circular cross-sectional shape. The outer water cooling wall 4 is disposed concentrically with the inner water cooling wall 3 at an outer position of the inner water cooling wall 3, and an annular combustion through which the combustion gas G passes between the outer water cooling wall 3 and the inner water cooling wall 3. A gas passage 5 is formed.
Further, the water cooling wall 4 on the outer side is provided with a water pipe 4a and a fin 4b that are slightly shifted in the circumferential direction from the position of the combustion gas passage port 3c formed in the inner water cooling wall 3, thereby removing the water pipe 4a and the fin 4b in the combustion gas passage 5 from each other. A combustion gas outlet 4c for allowing the combustion gas G to flow out is formed, and the combustion gas G flowing through the combustion gas passage 5 is discharged from the combustion gas outlet 4c to the flue 12.
Furthermore, an inspection port 4d is formed in the outer water cooling wall 4 by removing some of the water pipes 4a and fins 4b, and an inspection door 13 lined with a refractory can be opened and closed in the inspection port 4d. It is attached.

As shown in FIG. 2, an annular combustion gas passage 5 formed between the inner water cooling wall 3 and the outer water cooling wall 4 has a water pipe 4a near the combustion gas outlet 4c of the outer water cooling wall 4 and an inner water cooling wall. 3 is connected to a water pipe 3a in the vicinity of the combustion gas passage port 3c by a strip-like fin 4b 'extending in the vertical direction, so that one portion is closed, and the combustion gas G exiting the combustion gas passage port 3c is The gas flows in one direction in the annular combustion gas passage 5 and is exhausted from the combustion gas outlet 4c to the flue 12 after substantially making a round in the combustion gas passage 5. The upper space and the lower space of the annular combustion gas passage 5 are filled with a refractory for protecting the upper header 6 and the lower header 7 from the high-temperature combustion gas G.
The flow rate of the combustion gas G passing through the combustion gas passage 5 is set so as to prevent the wear of the water pipes of the two water-cooled walls 3 and 4 due to the ash in the combustion gas G. Of course.

As shown in FIG. 1, the upper header 6 and the lower header 7 are formed of a steel plate in the shape of a hollow structure having a rectangular cross section, and the headers 6 and 7 have an inner water cooling wall 3 and an outer water cooling wall. The upper and lower ends of each of the four water pipes 3a, 4a are connected in a continuous manner.
The upper header 6 is provided with a refractory ceiling wall 14 that closes the upper surface side of the secondary combustion chamber S ′.
Further, the upper header 6 is connected to a connecting pipe for guiding steam to the steam separator, and the lower header 7 is provided with a water supply pipe, a can water blow-out pipe, a return pipe from the steam separator, and the like. Each is connected (both not shown). A water level control cylinder (not shown) is attached between the upper header 6 and the lower header 7.

Next, the operation of the biofuel combustion apparatus 1 according to the first embodiment will be described.
First, the ignition burner 10 is ignited, and the combustion gas G ′ is ejected into the combustion chamber S. Combustion gas G ′ from the ignition burner 10 is ejected in the tangential direction along the inner peripheral surface of the combustion chamber S, and the inside of the combustion chamber S is swirled along the inner peripheral surface of the combustion chamber S by a cyclonic motion. Ascend to the outlet side of the combustion chamber S, reach the secondary combustion chamber S ′ through the orifice hole 8c ′, and during that time, the combustion chamber S is heated to a high temperature.

  When the flame of the ignition burner 10 is stabilized, an appropriate amount of combustion air a mixed with small-shaped biofuel f such as sawdust or rice husk is blown through the fuel / air supply pipe 11 and sent to the nozzle 9. Combustion air a mixed with biofuel f is blown from the blowing nozzle 9 into the combustion chamber S at a jetting speed of 10 m / s or more.

The biofuel f and the combustion air a blown into the combustion chamber S from the blow nozzle 9 are jetted at a high speed in the tangential direction along the inner peripheral surface of the combustion chamber S. While turning along the inner peripheral surface, water is first evaporated by the high-temperature combustion gas G ′ of the ignition burner 10, and combustion occurs while volatile components are evaporated.
Further, the biofuel f and the combustion air a blown into the combustion chamber S from the blow nozzle 9 do not immediately flow into the secondary combustion chamber S ′ by the orifice wall 8c provided at the outlet side opening of the combustion chamber S. Then, while moving in the combustion chamber S in a cyclonic motion, it descends toward the end wall 8b and burns.

At this time, the combustion temperature in the combustion chamber S in which the biofuel f is burned is desirably higher, but it is necessary to be equal to or lower than the melting point of ash generated by the combustion of the biofuel f. Therefore, the combustion temperature in the combustion chamber S is such that the peripheral wall 8a of the combustion section main body 8 provided with the blowing nozzle 9 is configured as a water cooling wall to cool the inside of the combustion chamber S, and the heat transfer in the combustion chamber S including the cooling area. Depending on the area and the air ratio of the combustion air a blown into the combustion chamber S, the combustion temperature is adjusted to the highest possible temperature at which ash does not melt.
The ignition burner 10 is stopped after a certain time has elapsed. This is because even if the ignition burner 10 is stopped, the combustion chamber S is capable of continuous combustion by self-heating.

  The ash generated by the combustion of the combustion gas G and biofuel f generated in the combustion chamber S rises in the center of the cyclone flow of the combustion air a while performing a cyclonic motion, and passes through the orifice hole 8c ′ while swirling. And flows into the secondary combustion chamber S ′.

At this time, a negative pressure portion is formed at the center of the combustion gas G that is in cyclonic motion, and a recirculation region is formed by the combustion gas G at the center of the combustion gas G. Such a recirculation action by the combustion gas G suppresses the stability of the flame and the generation of NOx. However, since the peripheral wall 8a of the combustion section main body 8 is configured as a water-cooled wall having a water-cooled jacket structure, the flame in the combustion chamber S is cooled, and thermal NOx is generated by cooling and lowering the flame. It is suppressed.
Further, the ash generated by the combustion of the biofuel f is extremely light and small, so it flows together with the combustion gas G and is discharged into the secondary combustion chamber S ′ without staying in the combustion chamber S. become. As a result, generation of clinker in the combustion chamber S can be prevented.

  The combustion gas G containing ash flowing from the combustion chamber S into the secondary combustion chamber S ′ is completely combusted in the secondary combustion chamber S ′ and gives heat to the inner water cooling wall 3 by radiant heat transfer and contact heat transfer. After that, it flows into the annular combustion gas passage 5 together with the ash from the combustion gas passage port 3 c formed in the upper part of the inner water cooling wall 3.

  At this time, the ash in the combustion gas G is generated by the combustion of the biofuel f having a small shape such as sawdust or rice husk, so that the combustion gas does not stay in the secondary combustion chamber S ′. Together with G, the gas is reliably and satisfactorily discharged from the combustion gas passage port 3c. As a result, generation of clinker in the secondary combustion chamber S ′ can be prevented.

  The combustion gas G containing ash flowing into the combustion gas passage 5 gives heat to the inner water-cooling wall 3 and the outer water-cooling wall 4 by contact heat transfer while substantially making a round in the combustion gas passage 5. Then, it is discharged from the combustion gas outlet 4c formed in the outer water cooling wall 4 to the flue 12 and reaches the cyclone dust collector (not shown) through the flue 12, where ash is separated and released into the atmosphere. Is done.

In this manner, the biofuel combustion apparatus 1 according to the first embodiment described above blows in the combustion chamber a in which biocombustion capable of air transport is blown into the combustion chamber S from the blow nozzle 9 and burns into the combustion chamber S. A cyclone flow is formed inside, the biofuel f is combusted in the cyclone flow, and the ash generated by the combustion is caused to flow together with the combustion gas G to be discharged from the combustion chamber S and the secondary combustion chamber S ′. Therefore, ash does not stay in the combustion chamber S and the secondary combustion chamber S ′, and generation of clinker can be prevented. In particular, the biofuel combustion apparatus 1 is configured such that the peripheral wall 8a of the combustion section main body 8 is a water-cooled wall so that the temperature in the combustion chamber S can be adjusted, and combustion is performed from the heat transfer area of the combustion chamber S and the blowing nozzle 9. The air ratio of the combustion air a blown into the chamber S is set so that the combustion temperature in the combustion chamber S is equal to or lower than the melting point of ash, so that the ash melts and adheres to the combustion chamber S. And the generation of clinker can be more reliably prevented.
In addition, the biofuel combustion apparatus 1 combusts the biofuel f blown together with the combustion air a from the blow nozzle 9 into the combustion chamber S while performing a cyclonic motion. Stirring and mixing of the fuel f and the combustion air a are promoted, and the residence time of the biofuel f in the combustion chamber S is increased, so that the biofuel f can be stably and efficiently burned.
Furthermore, since the biofuel combustion apparatus 1 performs the cyclonic combustion of the biofuel f in the combustion chamber S, combustion can be completed even if the axial length of the combustion chamber S is shortened. The combustion chamber S can be made compact. In particular, since the biofuel combustion apparatus 1 is provided with the orifice wall 8c at the outlet side opening of the combustion chamber S, the cyclone flow generated in the combustion chamber S is lowered in the combustion chamber S toward the end wall 8b. Then, since the inside of the combustion chamber S is raised, the length of the combustion chamber S in the axial direction can be shortened, and the combustion chamber S can be made more compact.
In addition, since the biofuel combustion apparatus 1 uses the peripheral wall 8a of the combustion section main body 8 provided with the blowing nozzle 9 as a water cooling wall having a water cooling jacket structure made of a steel plate, the biofuel f blown from the blowing nozzle 9 at high speed f. It is possible to prevent the peripheral wall 8a from being worn. However, since the end wall 8b of the combustion section main body 8 is made of a refractory material, heat is stored in the refractory material and combustion can be stabilized.
In addition, the biofuel combustion apparatus 1 blows and burns combustion air a mixed with biofuel f that can be transported by air into the combustion chamber S from the blow nozzle 9. Relatively small shapes such as rice husks, finely crushed wood chips, finely crushed bagasse, etc. can be used as fuel.
In addition, the biofuel combustion apparatus 1 uses a space surrounded by the inner water cooling wall 3 as a secondary combustion chamber S ′ communicating with the combustion chamber S of the combustion body 8 and the inner water cooling wall 3 and the outer water cooling wall 3. The structure is a steam boiler structure in which the space between the cooling wall 4 and the water cooling wall 4 is a combustion gas passage 5 that performs contact heat transfer, flows in the secondary combustion chamber S ′, and passes through the combustion gas G and the combustion gas passage 5. Since heat is applied to the water cooling walls 3 and 4 by contact heat transfer with the flowing combustion gas G, an efficient small capacity steam boiler can be obtained.

5 to 8 show a biofuel combustion apparatus 1 according to a second embodiment of the present invention. The biofuel combustion apparatus 1 blows into a combustion chamber S (primary combustion chamber S) having a circular cross section. Combustion air a mixed with biofuel f (for example, sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, finely crushed corn straw, etc.) that can be pneumatically conveyed from the nozzle 9 is contained in the combustion chamber S. A combustion section 2 that blows in the tangential direction of the peripheral surface to form a cyclone flow, burns the biofuel f in the cyclone flow, causes the generated ash to flow with the combustion gas G, and discharges it from the combustion chamber S; An annular hot-blast furnace wall 18 which is disposed on the outlet side of the combustion chamber S of the section 2 and forms a secondary combustion chamber S ′ having a circular cross section which communicates with the combustion chamber S of the combustion section 2 and the flue 12 inside. It is configured in a horizontal hot stove that blows The biofuel f mixed with the combustion air a and injected from the nozzle 9 is subjected to cyclone combustion in the combustion chamber S of the combustion section 2, and the generated ash is caused to flow together with the combustion gas G to move from the combustion chamber S to the secondary combustion chamber. It is made to discharge to the flue 12 through S ′. In addition, the biofuel combustion apparatus 1 removes ash from a hot air adjusted to a predetermined temperature with a cyclone dust collector (not shown) as necessary, and then a pyrolysis thermal furnace, a fluidized bed furnace, or the like. Can be supplied to.

As shown in FIGS. 5 and 6 , the combustion section 2 includes a cylindrical circumferential wall 8 a and a combustion chamber S (circular in cross section) formed of an end wall 8 b that closes one end opening (lower end opening) of the circumferential wall 8 a. The combustion section main body 8 in which the primary combustion chamber S) is formed and the peripheral wall 8a near the end wall 8b of the combustion section main body 8 are provided in a penetrating manner, and biofuel f capable of pneumatic transportation is mixed in the combustion chamber S. An injecting nozzle 9 for injecting combustion air a in the tangential direction of the inner peripheral surface of the combustion chamber S and an end wall 8b of the combustion section main body 8 are injected into the combustion chamber S from the injecting nozzle 9 together with the combustion air a. And an ignition burner 10 for igniting the biofuel f.

Specifically, as shown in FIGS. 5 and 6 , the combustion section main body 8 includes a cylindrical peripheral wall 8a formed of an air cooling wall formed of a steel plate having excellent heat resistance and an air cooling jacket structure, and one end opening of the peripheral wall 8a. The cross-sectional shape which consists of a refractory material which obstruct | occludes (lower-end part opening) is comprised from the end wall 8b formed in the thick flat plate shape, The combustion chamber S with a circular cross section is formed in the inside. Yes.
Further, as shown in FIG. 7 , the cooling air a ′ sent from the cooling fan (not shown) is blown into the air cooling jacket 8d ′ in the tangential direction and burned into the peripheral wall 8a of the combustion section main body 8 . An air nozzle 19 for cooling the inside of the chamber S is provided. This cooling air a 'is swirled in the air cooling jacket 8d' and cooled so that the combustion temperature in the combustion chamber S is below the melting point of ash, and then in the upstream portion of the secondary combustion chamber S '. In addition, the temperature of the combustion gas G is lowered by being introduced into the secondary combustion chamber S ′ through a nozzle hole (not shown) formed in the steel plate inside the annular hot stove wall 18.

As shown in FIGS. 5 and 6 , the blowing nozzle 9 has a posture along the tangential direction of the inner peripheral surface of the combustion chamber S to the peripheral wall 8 a of the combustion section main body 8 and from the end wall 8 b made of refractory material of the combustion section main body 8. It is provided in a penetrating manner at a position separated by a predetermined distance, and the combustion air a mixed with the biofuel f passes from the nozzle port 9a that opens into the combustion chamber S to the tangential direction along the inner peripheral surface of the combustion chamber S. Can be blown.

The distance between the blowing nozzle 9 and the end wall 8b (the distance between the axial center of the blowing nozzle 9 and the upper end surface of the end wall 8b) is a combustion gas G in the region between the blowing nozzle 9 and the end wall 8b. It is preferable to set according to the inner diameter d of the blowing nozzle 9 so that the recirculation is performed. Specifically, it is preferable to set the distance between the blowing nozzle 9 and the end wall 8b to be 2 to 3 times the inner diameter d of the blowing nozzle 9.
Further, the ejection speed of the combustion air a mixed with the biofuel f from the blowing nozzle 9 is 10 m / s or more, and the air ratio of the combustion air a blown into the combustion chamber S from the blowing nozzle 9 is 1.40. The inner diameter d of the blowing nozzle 9 and the inner diameter D of the combustion chamber S are preferably set to D / d> 5 to 8, respectively.

As shown in FIG. 5 , the ignition burner 10 is provided in the center of the end wall 8b of the combustion section main body 8 and is made of a metal ignition nozzle 10a having a circular cross-sectional shape that opens into the combustion chamber S, and the interior of the ignition nozzle 10a. The fuel injection nozzle 10b disposed at the axial position of the fuel injection nozzle 10b, and the flame holding plate 10c disposed at the tip of the fuel injection nozzle 10b, the combustion gas G 'generated by the combustion of the fuel is converted into the nozzle of the ignition nozzle 10a. It can be ejected into the combustion chamber S from the port 10a '.
Although not shown, the ignition burner 10 is provided with a flame detector at a position where the flame of the ignition burner 10 and the combustion flame caused by the combustion of the biofuel f can be detected . Is detected.
Further, the ignition burner 10 is provided with a combustion air supply unit 20 for supplying combustion air a into the ignition nozzle 10a. The combustion air supply unit 20 is disposed around the lower end of the wind box 20a provided on the lower surface of the end wall 8b of the combustion unit main body 8 and the ignition nozzle 10a, and swirls the combustion air a in the wind box 20a. And a swirl vane 20b that is supplied to the ignition nozzle 10a and blows combustion air a from a combustion air blower (not shown) into the wind box 20a, and the combustion air a in the wind box 20a is swirled. It is rotated by 20b and supplied into the ignition nozzle 10a.

The annular hot-blast furnace wall 18 has an air-cooled jacket structure made of a steel plate (the inner steel plate is excellent in heat resistance, and the outer steel plate is a normal steel plate). A secondary combustion chamber S ′ having a circular cross section larger than the inner diameter of the combustion chamber S is formed.
Further, as shown in FIG. 8 , the upstream end of the annular hot stove wall 18 (the lower end of the hot stove wall 18 shown in FIG. 5 ) is supplied with a cooling fan (not shown). An air nozzle 19 is provided to cool the inside of the combustion chamber S and the furnace wall by blowing air a 'into the air cooling jacket 18a in the tangential direction. The cooling air a ′ is swirled in the air cooling jacket 18a to cool the inside of the secondary combustion chamber S ′, and then is applied to the steel plate inside the hot stove wall 18 in the downstream portion of the secondary combustion chamber S ′. The temperature of the combustion gas G is lowered by being introduced into the secondary combustion chamber S ′ from the formed nozzle hole (not shown).
Further, dilution air a ″ is introduced into the downstream end portion of the annular hot stove wall 18 (the upper end portion of the hot stove wall 18 shown in FIG. 5 ) to the outlet side of the secondary combustion chamber S ′. A dilution air supply mechanism 21 for adjusting the temperature of the gas discharged from the combustion chamber S ′ is provided, which is provided at the downstream end of the annular hot stove wall 18 as shown in FIG. A dilution air supply pipe 21a, a damper 21b interposed in the dilution air supply pipe 21a, and a dilution fan 21c connected to the dilution air supply pipe 21a, and dilution air a ″ from the dilution fan 21c. To the outlet side of the secondary combustion chamber S ′ on the downstream side to obtain hot air at a predetermined temperature.

In the biofuel combustion apparatus 1 according to the second embodiment described above, the blowing nozzle 9 is provided in a penetrating manner in the peripheral wall 8a near the end wall 8b of the combustion unit body 8, so that the cyclone flow is directed upward from the blowing nozzle 9. The recirculation region is formed at the center of the combustion chamber S and contributes to combustion. Furthermore, a recirculation region is also formed in the combustion chamber S below the blowing nozzle 9 and contributes to the stability of the flame.
Accordingly, the biofuel combustion apparatus 1 can achieve good cyclone combustion in the same manner as the biofuel combustion apparatus 1 according to the second embodiment, and can stably and efficiently burn the biofuel f. In addition, the combustion chamber S can be made compact.
Further, the biofuel combustion apparatus 1 causes the ash generated in the combustion chamber S to flow together with the combustion gas G and is discharged from the combustion chamber S to the flue 12 through the secondary combustion chamber S ′. Generation of clinker can be prevented. However, the peripheral wall 8a of the combustion section main body 8 is configured as an air cooling wall having an air cooling jacket structure made of a steel plate so that the temperature in the combustion chamber S can be adjusted, and the heat transfer area of the combustion chamber S (the cooling area of the peripheral wall 8a is reduced). And the air ratio of the combustion air a that is blown into the combustion chamber S from the blowing nozzle 9 is set so that the combustion temperature in the combustion chamber S is equal to or lower than the melting point of ash. It can be surely prevented.
Further, in this biofuel combustion apparatus 1, the peripheral wall 8 a of the combustor main body 8 provided with the blowing nozzle 9 is a peripheral wall 8 a made of a steel plate, and therefore the peripheral wall 8 a portion of the biofuel f blown from the blowing nozzle 9 at a high speed Can prevent wear. However, since the end wall 8b of the combustion section main body 8 is made of a refractory material, heat is stored in the refractory material and combustion can be stabilized.

In the biofuel combustion apparatus 1 according to the first and second embodiments described above, only one blowing nozzle 9 is provided on the peripheral wall 8a of the combustion section main body 8, but other embodiments are provided. In this case, as shown in FIG. 9 , the blowing nozzles 9 are arranged on the peripheral wall 8 a of the combustion section main body 8 in parallel in the circumferential direction of the combustion chamber S, and from each blowing nozzle 9 to the inner peripheral surface of the combustion chamber S. The combustion air a mixed with the biofuel f may be blown in the tangential direction along the tangential direction.
That is, the biofuel combustion apparatus 1 is arranged with 180 ° intervals in the circumferential direction of the combustion chamber S without striking the injection nozzles 9 in the axial direction of the combustion chambers S. The combustion air a mixed with the biofuel f is blown in the direction and the tangential direction along the inner peripheral surface of the combustion chamber S.
Thus, when the combustion air a mixed with the biofuel f is blown into the combustion chamber S from the plurality of blowing nozzles 9, a stronger cyclone flow is formed in the combustion chamber S, and the biofuel f and the combustion are combusted. Stirring and mixing with the working air a can be further promoted, and the flame can be shortened.

In the biofuel combustion apparatus 1 shown in FIG. 9 , the blowing nozzle 9 is arranged in parallel with the circumferential wall 8 a of the combustion unit body 8 in the circumferential direction of the combustion chamber S. Combustion air a in which biocombustion is mixed is blown into the peripheral wall 8a of the main body 8 in parallel with the axial direction of the combustion chamber S along the inner peripheral surface of the combustion chamber S from each blowing nozzle 9. You may do it.

Furthermore, in the biofuel combustion apparatus 1 according to the first and second embodiments described above, the blowing nozzle 9 provided in a penetrating manner in the peripheral wall 8a of the combustion section main body 8 is in a horizontal posture. In another embodiment, the blowing nozzle 9 may be provided in a penetrating manner on the peripheral wall 8a of the combustion section main body 8 in a downward inclined posture.

In addition, in the biofuel combustion apparatus 1 according to the first and second embodiments described above, the combustion gas G exiting the combustion gas passage 3c passes through the combustion gas passage 5 as shown in FIG. In the other embodiment, the combustion gas outlet 4c is formed at the outer water cooling wall 4 at a position 180 degrees opposite to the combustion gas passage 3c. The combustion gas G exiting 3c may flow in the left-right direction in the combustion gas passage 5, and may be exhausted from the combustion gas outlet 4c to the flue 12 after substantially half-circulating the combustion gas passage 5 (not shown). .

1 is a biofuel combustion apparatus, 2 is a combustion section, 3 is an inner water cooling wall, 4 is an outer water cooling wall, 5 is a combustion gas passage, 6 is an upper header, 7 is a lower header, 8 is a combustion section body, 8a Is a peripheral wall, 8b is an end wall, 8c is an orifice wall, 9 is a blow nozzle, 10 is an ignition burner, 12 is a flue , 17 is a heat exchanger, 18 is a hot stove wall, a is combustion air, and f is Biofuel, G is a combustion gas, S is a combustion chamber, S 'is a secondary combustion chamber.

Claims (6)

Combustion with a biofuel (f) that can be transported by air such as sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, etc. Air (a) is blown in the tangential direction of the inner peripheral surface of the combustion chamber (S) to form a cyclone flow, the biofuel (f) is combusted in the cyclone flow, and the generated ash together with the combustion gas (G) A combustion section (2) that flows and discharges from the combustion chamber (S), and a circular section 2 that is disposed on the combustion chamber (S) outlet side of the combustion section (2) and communicates with the combustion chamber (S) inward. An annular inner water cooling wall (3) forming a secondary combustion chamber (S '), an annular outer water cooling wall (4) disposed outside the inner water cooling wall (3), and an inner water cooling Formed between the wall (3) and the outer water cooling wall (4), the secondary combustion chamber (S ') and the flue ( 2) an annular combustion gas passage (5) communicating with the two water-cooled walls (3), (4), and an upper header (6) and a lower header (7) connected to each other, The biofuel (f) mixed and injected into the combustion air (a) from the blowing nozzle (9) is subjected to cyclone combustion in the combustion chamber (S), and the generated ash is caused to flow together with the combustion gas (G) to form the combustion chamber. A biofuel combustion apparatus (1) for discharging from (S) to a flue (12) through a secondary combustion chamber (S ') and a combustion gas passage (5), wherein the combustion section (2) A cylindrical peripheral wall (8a), an end wall (8b) that closes one end opening of the peripheral wall (8a), and an annular hole that is provided in the other end opening of the peripheral wall (8a) to form an orifice hole (8c ') It consists of an orifice wall (8c) and is exited by an orifice wall (8c) inward A combustion chamber body (8) having a circular combustion chamber (S) with a narrowed cross section and a peripheral wall (8a) near the orifice wall (8c) of the combustion chamber body (8) are provided in a penetrating manner. A combustion nozzle (9) for blowing combustion air (a) mixed with biofuel (f) that can be pneumatically transported into (S) in a tangential direction of the inner peripheral surface of the combustion chamber (S); And an ignition burner (10) for igniting the biofuel (f) blown together with the combustion air (a) into the combustion chamber (S) from the blow nozzle (9), The opening area of the orifice hole (8c ') is set so that the combustion air (a) mixed with the biofuel (f) blown into the combustion chamber (S) from the blow nozzle (9) immediately enters the combustion chamber (S). Do not flow into the secondary combustion chamber (S ') through the orifice hole (8c'). The distance between the blowing nozzle (9) and the orifice wall (8c) was blown into the combustion chamber (S) from the blowing nozzle (9) while being set to 1/2 or more of the cross-sectional area of the combustion chamber (S). The blowing nozzle (9) prevents the combustion air (a) mixed with the biofuel (f) from flowing into the secondary combustion chamber (S ') through the orifice hole (8c') immediately from the combustion chamber (S). A biofuel combustion apparatus, which is set to be twice to three times the inner diameter (d). Combustion with a biofuel (f) that can be transported by air such as sawdust, rice husk, finely crushed wood chips, finely crushed bagasse, etc. Air (a) is blown in the tangential direction of the inner peripheral surface of the combustion chamber (S) to form a cyclone flow, the biofuel (f) is combusted in the cyclone flow, and the generated ash together with the combustion gas (G) It is arranged on the combustion chamber (S) outlet side of the combustion section (2) that flows and discharges from the combustion chamber (S), and to the combustion chamber (S) and the flue (12) inward. An annular hot-blast furnace wall (18) having an air- cooled jacket structure composed of an inner steel plate and an outer steel plate forming a secondary combustion chamber (S ') having a circular cross section in communication is combusted from the blowing nozzle (9). Biofuel (f In the combustion chamber (S), and the generated ash flows together with the combustion gas (G) and is discharged from the combustion chamber (S) to the flue (12) through the secondary combustion chamber (S '). The biofuel combustion apparatus (1) includes a cylindrical peripheral wall (8a) and an end wall (8b) that closes one end opening of the peripheral wall (8a). A combustion section main body (8) having a circular combustion chamber (S) having a circular cross section and a peripheral wall (8a) near the end wall (8b) of the combustion section main body (8) are provided in a penetrating manner in the combustion chamber (S). A combustion nozzle (9) for injecting combustion air (a) mixed with biofuel (f) that can be pneumatically transported into the tangential direction of the inner peripheral surface of the combustion chamber (S) and a combustion section main body (8) are provided. Biofuel which was blown into the combustion chamber (S) from the blow nozzle (9) together with the combustion air (a) And a ignition burner (10) for igniting (f), the addition, the inside of the steel plate of the annular hot-air furnace wall (18), 'cooling air to (a 2 primary combustion chamber (S)' a) In addition to forming a nozzle hole for injection , dilution air (a ″) is introduced to the outlet side of the secondary combustion chamber (S ′) at the downstream end of the annular hot-blast furnace wall (18) to provide the secondary. A biofuel combustion apparatus comprising a dilution air supply mechanism (21) for adjusting a temperature of a gas discharged from the combustion chamber (S ').   The peripheral wall (8a) and the orifice wall (8c) of the combustion section main body (8) are configured as a water cooling wall having a water cooling jacket structure made of steel plate to cool the inside of the combustion chamber (S), and heat transfer in the combustion chamber (S) The air ratio of the combustion air (a) blown into the area and the combustion chamber (S) is set to 1.40 to 1.90 so that the combustion temperature in the combustion chamber (S) is below the melting point of ash. The biofuel combustion apparatus according to claim 1.   The peripheral wall (8a) of the combustion section main body (8) is configured as an air cooling wall having an air cooling jacket structure made of a steel plate to cool the inside of the combustion chamber (S), and the heat transfer area of the combustion chamber (S) and the combustion chamber (S 3) The air ratio of the combustion air (a) blown into the inside of the combustion chamber (S) is set to 1.40 to 1.90 so that the combustion temperature in the combustion chamber (S) is not higher than the melting point of ash. The biofuel combustion apparatus as described.   The combustion air (a) mixed with biofuel (f) is blown into the combustion chamber (S) from the blowing nozzle (9) at a flow rate of 10 m / s or more. A biofuel combustion apparatus according to claim 1.   Combustion in which the injection nozzle (9) is arranged in parallel with the circumferential direction of the combustion chamber (S) on the peripheral wall (8a) of the combustion section main body (8), and biofuel (f) is mixed from each injection nozzle (9). The biofuel combustion apparatus according to claim 1 or 2, wherein the working air (a) is blown into the combustion chamber (S) in a tangential direction of the inner peripheral surface thereof.

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