JP6991939B2 - Burner - Google Patents

Description

The present invention relates to a burner that uses biomass as a fuel.

As one of the measures to reduce CO ₂ in the problem of global warming, it is considered to promote the use of renewable energy. Regarding renewable energy, the use of biomass as a fuel is drawing attention from the viewpoint of carbon neutrality.

As a biomass fuel, a powder biomass fuel (biomass powder fuel) produced by powdering woody biomass such as wood is known.

Burners using this type of biomass-derived powdered biomass fuel have been conventionally proposed (see, for example, Patent Document 1).

This burner is provided with a cylindrical burner tube that is sideways and has one end open, a powder fuel supply line is connected to the other end of the burner tube, and a primary air supply port and an ignition means are provided. Further, the secondary air supply port is provided at a position closer to the opening on one end side of the burner pipe than the primary air supply port.

The burner having such a configuration partially burns the powder biomass fuel supplied from the powder fuel supply pipeline at a low air ratio by the primary air supplied from the primary air supply port so as to form a swirling flow in the burner pipe. Further, when the volatile components in the powder biomass fuel are vaporized by the partial combustion, the burner forms a swirling flow from the secondary air supply port into the burner pipe by using the remaining air required for combustion as secondary air. It is supposed to be supplied so as to completely burn the biomass powder fuel.

Japanese Unexamined Patent Publication No. 2011-7478

By the way, the burner shown in Patent Document 1 has a configuration in which a powdery biomass fuel is burned in a burner pipe extending in one direction. Therefore, in this burner, the powder biomass fuel used is required to have a density and particle size that can be transported by being suspended in the swirling flow of the primary air and the swirling flow of the secondary air formed in the burner pipe, and the primary air is also required. And combustibility that can be completely combusted while being conveyed in the burner pipe by the swirling flow of secondary air is required.

Therefore, the burner shown in Patent Document 1 is actually that the powdery biomass fuel that can be used is made of woody biomass and the particle size is limited to 300 μm or less.

Therefore, in the burner shown in Patent Document 1, a biomass fuel having a particle size larger than 300 μm, a biomass fuel derived from biomass having lower flammability and calorific value than woody biomass, a biomass fuel having a larger water content, etc. Biomass fuel with different properties may fall and stay in the burner tube, or part of the biomass fuel may be released from the opening of the burner tube as an unburned solid. That is difficult.

Therefore, the present invention aims to provide a burner capable of improving the combustibility of the biomass fuel in the combustion chamber so that the biomass fuel having a wider range of properties can be used as compared with the conventional one. It is a thing.

In order to solve the above problems, the present invention is formed on a cylindrical first combustion chamber extending in the vertical direction, a flow layer provided on the lower end side of the first combustion chamber, and the top of the first combustion chamber. An arched or dome-shaped ceiling wall, a second combustion chamber that is cylindrical and has one end side in the axial direction connected to the side of the upper end side of the first combustion chamber, and the above. A flame outlet provided on the other end side in the axial direction in the second combustion chamber, a primary air supply unit that supplies primary air that also serves as flow air for the flow medium to the flow layer, and the first combustion chamber. A secondary air supply nozzle provided on the peripheral wall in a tangential direction, a tertiary air supply nozzle provided on the peripheral wall of the second combustion chamber, and a fuel supply nozzle for supplying biomass fuel to the first combustion chamber. , And a burner having a configuration.

The secondary air supply nozzle may be configured to be provided below the connection position of the second combustion chamber on the peripheral wall of the first combustion chamber.

The fuel supply nozzle may be configured to be provided above the installation position of the secondary air supply nozzle on the peripheral wall of the first combustion chamber.

The tertiary air supply nozzle may be provided in a posture along the tangential direction on the peripheral wall of the second combustion chamber.

The ceiling wall may have an arch shape, and the ceiling wall and one end in the axial direction of the second combustion chamber may be arranged in a coaxial center and have the same radius.

According to the burner of the present invention, it is possible to improve the combustibility of the biomass fuel in the combustion chamber.

It is a schematic diagram which shows the 1st Embodiment of a burner. It is a BB direction arrow view of FIG. 1 (a). FIG. 1 (a) is a view taken along the line CC. It is a figure for demonstrating the velocity distribution in the 1st combustion chamber of the burner of FIG. It is a schematic diagram which shows the 2nd Embodiment of a burner.

Hereinafter, the burner of the present disclosure will be described with reference to the drawings.

[First Embodiment]
1A and 1B show a first embodiment of a burner, FIG. 1A is a schematic front view of cutting, and FIG. 1B is a view taken along the line AA of FIG. 1A. FIG. 2 is a view taken along the line BB in FIG. 1 (a). FIG. 3 is a view taken along the line CC of FIG. 1 (a). FIG. 4 is a schematic diagram for explaining the flow velocity distribution in the first combustion chamber of the burner of FIG.

The burner of the present embodiment is shown by reference numeral 1 in FIGS. 1 (a) and 1 (b), and has a cylindrical first combustion chamber 2 extending in the vertical direction and a flow provided on the lower end side of the first combustion chamber 2. The layer 3, the arch-shaped (semi-cylindrical wall-shaped) ceiling wall 4 formed at the top of the first combustion chamber 2, and the laterally extending cylindrical shape with one end side in the axial direction being the upper end side of the first combustion chamber 2. A second combustion chamber 5 connected to the side of the second combustion chamber 5 and a flame ejection port 6 provided on the other end side in the axial direction of the second combustion chamber 5 are provided.

Further, the burner 1 of the present embodiment has a posture along the tangential direction with the primary air supply unit 8 that supplies the primary air 9 that also serves as the flow air of the flow medium 7 to the flow layer 3 and the peripheral wall 10 of the first combustion chamber 2. The secondary air supply nozzle 11 provided in the above, the tertiary air supply nozzle 13 provided on the peripheral wall 12 of the second combustion chamber 5, the fuel supply nozzle 14 for supplying the biomass fuel 15 to the first combustion chamber 2, and the ignition. It is configured to include an ignition burner 16 as a means.

The first combustion chamber 2, the ceiling wall 4, and the second combustion chamber 5 are made of refractory material.

The ceiling wall 4 is arranged coaxially with the axis of the second combustion chamber 5, and has a semi-cylindrical shape having the same radius as one end in the axial direction of the second combustion chamber 5. As a result, in the second combustion chamber 5, the upper half of the peripheral wall 12 on one end side in the axial direction is connected to the ceiling wall 4 without a step.

The fluidized bed 3 is filled with a fluidized medium 7 of solid particles such as sand. A primary air supply unit 8 is provided below the fluidized bed 3. The primary air supply unit 8 includes an air diffuser plate 17 such as a porous plate or a porous plate through which air can pass while blocking the passage of the flow medium 7, a primary air supply nozzle 18, and an air box 19. It is said that it has a structure. An air supply line 21 that guides the primary air 9 that also serves as flowing air from the blower 20 is connected to the air box 19.

As a result, in the fluidized bed 3, the fluidized medium 7 is fluidized by the primary air 9 introduced from below through the air box 19, the primary air supply nozzle 18, and the air diffuser plate 17 and ejected upward.

In addition, the primary air supply unit 8 replaces the configuration in which the primary air 9 is supplied to the flow medium 7 from below through the air diffuser plate 17, and the primary air supply unit 8 has an air diffuser tube (not shown) inserted and arranged at the filling point of the flow medium 7. As a provided configuration, a method may be used in which primary air 9 also serving as fluidized air is supplied from an air diffuser pipe to fluidize the fluidized medium 7 in the fluidized bed 3.

Therefore, the fluidized bed 3 supports the biomass fuel 15 supplied from the fuel supply nozzle 14 to the first combustion chamber 2 and falling to the fluidized bed 3 by the fluidized fluid medium 7, and is further stirred. However, it can be burned using the primary air 9. At this time, in the flow layer 3, the supply amount of the primary air 9 and the supply amount of the biomass fuel 15 dropped and supplied to the flow layer 3 from the fuel supply nozzle 14 are such that partial combustion of the biomass fuel 15 occurs, that is, , It is adjusted so that the complete combustion of the biomass fuel 15 is oxygen deficient. Therefore, in the fluidized layer 3, partial combustion of the biomass fuel 15 is performed, and the remaining combustion of the biomass fuel 15 is dried and pyrolyzed and gasified by utilizing the combustion heat generated by the partial combustion.

As described above, when the biomass fuel 15 that falls to the fluidized bed 3 is generated, the burner 1 of the present embodiment can support the biomass fuel 15 by the fluidized medium 7 and slowly burn the biomass fuel 15 while further stirring. .. Further, the fire resistant material and the flow medium 7 constituting the first combustion chamber 2 are heated by the combustion heat of the biomass fuel 15 and are in a state of storing heat. Therefore, in the burner 1 of the present embodiment, even if the biomass fuel 15 used has changes in combustibility due to changes in properties such as particle size, water content, and contained components, changes in the combustion state in the fluidized bed 3 occur. It is possible to continuously burn the biomass fuel 15 while suppressing the above.

In the first combustion chamber 2, the region near the lower part of the first combustion chamber 2 directly above the fluidized bed 3 is partially burned and pyrolyzed and gasified by the biomass fuel 15 supported by the fluidized bed 3 as described above. It becomes the combustion unit 22.

The combustible gas generated by the thermal decomposition gasification of the biomass fuel 15 in the combustion chamber 22 is combined with the combustion gas generated by the partial combustion of the biomass fuel 15 and the primary air 9 after being used as fluidized air in the fluidized layer 3. , Flows upward inside the first combustion chamber 2 toward the connection portion with the second combustion chamber 5 which is the outlet of the first combustion chamber 2.

On the peripheral wall 10 of the first combustion chamber 2, a secondary air supply nozzle 11 is provided at a position above the combustion unit 22 and below the connection portion with the second combustion chamber 5 by a set dimension. It is provided.

As shown in FIG. 2, the secondary air supply nozzle 11 is arranged along a plane perpendicular to the axis of the first combustion chamber 2 and along the tangential direction of the peripheral wall 10 of the first combustion chamber 2, for example, the peripheral wall. It is provided at three locations at equal intervals in the circumferential direction of 10.

An air supply line 21a that guides the secondary air 23 from the blower 20 is connected to the secondary air supply nozzle 11.

As a result, the secondary air supply nozzle 11 can supply the secondary air 23 to a position above the combustion unit 22 in the first combustion chamber 2 by blowing it in the direction along the peripheral wall 10.

As shown in FIGS. 1A and 1B, in the first combustion chamber 2, the secondary air 23 blown from the secondary air supply nozzle 11 flows in the circumferential direction along the peripheral wall 10 and gradually undergoes the first combustion. An upward swirling flow 24 is formed inside the first combustion chamber 2 in order to face the connection portion with the second combustion chamber 5 which is the outlet of the chamber 2.

The number of secondary air supply nozzles 11 provided on the peripheral wall 10 of the first combustion chamber 2 in the circumferential direction may be 1 or 2, or may be 4 or more. Further, when a plurality of secondary air supply nozzles 11 are provided in the circumferential direction of the peripheral wall 10, it is preferable that the intervals between the secondary air supply nozzles 11 adjacent to each other in the circumferential direction are uniform, but even if they are not uniform. good. Further, when a plurality of secondary air supply nozzles 11 are provided on the peripheral wall 10, all the secondary air supply nozzles 11 are arranged so as not to be aligned on one plane perpendicular to the axis of the first combustion chamber 2. May be good. For example, the secondary air supply nozzle 11 may be provided on the peripheral wall 10 in an arrangement of two stages in the vertical direction or a plurality of stages of three or more stages. The posture of the secondary air supply nozzle 11 is such that the swirling flow 24 as described above can be formed inside the first combustion chamber 2 with respect to the plane perpendicular to the axis of the first combustion chamber 2. It may be tilted or may be tilted from the tangential direction of the peripheral wall 10.

The fuel supply nozzle 14 is provided at a position upward by a dimension set from the installation location of the secondary air supply nozzle 11 on the peripheral wall 10 of the first combustion chamber 2 in a posture facing diagonally downward.

The fuel supply nozzle 14 is connected to a fuel supply unit (not shown) that supplies a controlled amount of biomass fuel 15 together with pressurized air for injection.

The biomass fuel 15 is a biomass powder having a particle size of several hundred micrometers to about 1,000 micrometers, and the raw material of biomass that is desired to be used as wood or other fuel is pulverized as necessary. Manufactured.

As a result, the burner 1 of the present embodiment can inject and supply the biomass fuel 15 diagonally downward from the fuel supply nozzle 14 to the first combustion chamber 2.

In the first combustion chamber 2, the direction of the main flow of the airflow including the combustible gas and the combustion gas, the primary air 9, and the secondary air 23 generated in the combustion unit 22 is the first from below in the first combustion chamber 2. 2 There is an upward flow with a connection with the combustion chamber 5.

Therefore, in the burner 1 of the present embodiment, the biomass fuel 15 can be injected from the fuel supply nozzle 14 in a direction facing the main flow of the air flow in the first combustion chamber 2. As a result, in the burner 1 of the present embodiment, of the biomass fuel 15 injected from the fuel supply nozzle 14 and supplied in the first combustion chamber 2, the biomass fuel 15 that does not fall into the flow layer 3 is put into the first combustion chamber. It can be mixed and dispersed in the airflow in 2, and can promote the formation of a two-phase flow by the gas and the biomass fuel 15.

The supply amount of the secondary air 23 is the total amount of the air used for injecting the biomass fuel 15 from the primary air 9 and the fuel supply nozzle 14, and the total amount of air is the complete amount of the biomass fuel 15 supplied from the fuel supply nozzle 14. It is adjusted so that there is a lack of oxygen for combustion. Therefore, in the first combustion chamber 2, partial combustion of the biomass fuel 15 supplied from the fuel supply nozzle 14 is performed, and the combustion heat generated by this partial combustion is used to generate the thermal decomposition gas of the rest of the biomass fuel 15. Is done.

Here, regarding the biomass fuel 15, the behavior and flammability in the first combustion chamber 2 will be described separately for small particle size particles, medium particle size particles, and large particle size particles. The small particle size particles are a group of particles that can rise on the main flow of the airflow generated upward in the first combustion chamber 2 and that the entire particles burn quickly when ignited. The medium-sized particles can float on the main flow of the airflow generated upward in the first combustion chamber 2, and when ignited, it takes longer than the small-sized particles to burn the entire particles. A group of particles. The large particle size particles are a group of particles that cannot float and fall into the fluidized bed 3 in the main flow of the airflow generated upward in the first combustion chamber 2.

When the biomass fuel 15 is supplied from the fuel supply nozzle 14 into the first combustion chamber 2, the small particle size particles of the biomass fuel 15 are formed in the first combustion chamber 2 and the upward airflow, particularly the secondary. It is quickly dispersed and mixed with respect to the swirling flow 24 of the air 23. Therefore, the temperature in the first combustion chamber 2 is equal to or higher than the ignition temperature of the biomass fuel 15, or the seed is in a region through which the biomass fuel 15 supplied from the fuel supply nozzle 14 and dispersed in the secondary air 23 passes. If a fire is present, the small particle size particles of the biomass fuel 15 are ignited in a state of being suspended in the space in the swirling flow 24 of the secondary air 23 and burned promptly. Combustion of fuel in a state of floating in space in this way is hereinafter referred to as space combustion.

In this way, the flame when the small particle size particles of the biomass fuel 15 are swirled on the swirling flow 24 and quickly burned includes the small particle size particles from the fuel supply nozzle 14 in the first combustion chamber 2. However, it will continue to occur while the biomass fuel 15 is being supplied. Therefore, the flame held in the first combustion chamber 2 on the swirling flow 24 serves as a pilot fire for igniting the biomass fuel 15 newly supplied into the first combustion chamber 2 from the fuel supply nozzle 14. It will be possible to use it.

When the medium-sized particles of the biomass fuel 15 are supplied into the first combustion chamber 2 from the fuel supply nozzle 14, the upward airflow formed in the first combustion chamber 2, particularly the swirl of the secondary air 23. It is quickly dispersed and mixed with respect to the flow 24. Therefore, the medium-sized particles also start burning in the same manner as the small-sized particles, but it takes longer than the small-sized particles to burn as a whole. Therefore, when the medium particle size particles are ignited, they start partial combustion while swirling on the swirling flow 24 of the secondary air 23, and are pyrolyzed and gasified.

When the large particle size particles of the biomass fuel 15 are supplied from the fuel supply nozzle 14 into the first combustion chamber 2, they are once taken into the swirling flow 24 of the secondary air 23, but fall in the swirling flow 24 due to their own weight. .. Therefore, the large particle size particles fall into the fluidized bed 3 at the bottom of the first combustion chamber 2 as shown by the alternate long and short dash line in FIG. 1B without being accompanied by the swirling flow 24.

As described above, the large particle size particles that have fallen into the fluidized bed 3 are partially burned, dried, and pyrolyzed and gasified using the primary air 9 while being supported and stirred by the flowing fluidized medium 7. ..

The above-mentioned small particle size particles, medium particle size particles, and large particle size particles are convenient classifications for explaining the behavior and combustibility of the particles of the biomass fuel 15, and the classification according to the particle size is strict. is not it. Therefore, even if the particles of the biomass fuel 15 have the same particle size, whether or not they are easily accompanied by the difference in combustibility and the swirling flow 24 due to the density of the particles, the amount of water contained, and the like. Depending on these differences, it may belong to any of the above-mentioned small particle size particles, medium particle size particles, and large particle size particles.

Further, in the first combustion chamber 2, a part of the combustible gas generated by the pyrolysis gasification of the biomass fuel 15 is burned using the secondary air 23.

Therefore, in the burner 1 of the present embodiment, when the biomass fuel 15 is supplied from the fuel supply nozzle 14 into the first combustion chamber 2 and combustion is performed by the primary air 9 and the secondary air 23, the first combustion chamber 2 is used. A high-temperature combustion gas is generated inside due to the partial combustion of the biomass fuel 15 and the combustion of a part of the combustible gas. Therefore, in the first combustion chamber 2, the high-temperature combustion gas, the balance of the combustible gas, and the primary air 9 after being used as fluidized air in the fluidized layer 3 are first burned by the secondary air 23. An air flow accompanied by an upward swirling flow 24 along the peripheral wall 10 of the chamber 2 is generated.

FIG. 4 shows the velocity distribution of the upward component of the airflow flowing in the first combustion chamber 2.

When the primary air 9 that has passed through the fluidized bed 3 flows upward through the combustion portion 22 which is a region near the lower part of the first combustion chamber 2, a boundary layer is formed in the vicinity of the peripheral wall 10, so that the velocity distribution of the upward component of the airflow is generated. As shown by S1 in FIG. 4, the speed near the axis (center portion) of the first combustion chamber 2 is higher than the speed near the peripheral wall 10.

On the other hand, above the installation position of the secondary air supply nozzle 11, the secondary air 23 supplied from the secondary air supply nozzle 11 forms a swirling flow 24 along the peripheral wall 10, resulting in an air flow. As for the velocity distribution of the upward component, as shown by S2 in the figure, the velocity near the peripheral wall 10 is larger than the velocity near the axis of the first combustion chamber 2.

Therefore, at the place where the swirling flow 24 is formed in the first combustion chamber 2, the vicinity of the axis of the first combustion chamber 2 inside the swirling flow 24 is based on the vicinity of the peripheral wall 10 where the swirling flow 24 is formed. It becomes a relatively negative pressure region. As a result, in the first combustion chamber 2, a part of the airflow that has flowed upward as the swirling flow 24 is folded back from upward to downward as shown by the alternate long and short dash line in FIGS. 1 (a) and 1 (b), as described above. A reflux 25 toward the inside of the swirling flow 24, which is a relative negative pressure region, is generated.

Further, the first combustion chamber 2 is provided with an arch-shaped ceiling wall 4 on the upper side. Therefore, the airflow containing the upward component generated in the first combustion chamber 2 is blocked by the ceiling wall 4 in the upper direction, which is the traveling direction thereof.

At this time, since the ceiling wall 4 has an arch shape, in the first combustion chamber 2, the airflow in the vicinity of the peripheral wall 10 has a higher speed of the upward component than in the vicinity of the axis of the first combustion chamber 2. That is, when the swirling flow 24 reaches the upper end of the peripheral wall 10, it is guided along the arched surface of the ceiling wall 4.

After that, the airflow guided along the surface of the ceiling wall 4 gathers at the top of the ceiling wall 4, and therefore, in the vicinity of the top of the ceiling wall 4, as shown by the alternate long and short dash line in FIGS. 1 (a) and 1 (b), An airflow that folds back from upward to downward is generated. This airflow becomes a stronger reflux 26 toward the inside of the swirling flow 24, which is a relative negative pressure region as described above.

It is the airflow containing the high-temperature combustion gas generated by the combustion of the biomass fuel 15 that produces the reflux 25 and the reflux 26. Therefore, in the burner 1 of the present embodiment, the airflow containing the high-temperature combustion gas is sequentially supplied as reflux 25 and reflux 26 near the axis near the upper part of the first combustion chamber 2 and maintained in a high-temperature atmosphere. The heat reflux region 27 as shown by the alternate long and short dash line is formed in FIGS. 1 (a) and 1 (b).

After that, the airflow containing the high-temperature combustion gas and the combustible gas generated in the first combustion chamber 2 sequentially flows into the second combustion chamber 5 from the upper end side of the first combustion chamber 2.

As shown in FIG. 1A, in the second combustion chamber 5, one end side in the axial direction is the upstream side connected to the first combustion chamber 2, and the flame ejection port 6 side on the other end side in the axial direction is. , On the downstream side.

The second combustion chamber 5 is provided with a tertiary air supply nozzle 13 at a position closer to one end in the axial direction on the peripheral wall 12.

In the present embodiment, as shown in FIG. 3, the tertiary air supply nozzle 13 is in a posture along a plane perpendicular to the axis of the second combustion chamber 5 and along the tangential direction of the peripheral wall 12 of the second combustion chamber 5. For example, it is provided at three locations at equal intervals in the circumferential direction of the peripheral wall 12.

An air supply line 21b that guides the tertiary air 28 from the blower 20 is connected to the tertiary air supply nozzle 13.

As a result, the tertiary air supply nozzle 13 can supply the tertiary air 28 to the second combustion chamber 5 by blowing it in the direction along the peripheral wall 12.

As for the supply amount of the tertiary air 28, the total amount of air combined with the air used for injecting the biomass fuel 15 from the primary air 9, the secondary air 23, and the fuel supply nozzle 14 is the biomass supplied from the fuel supply nozzle 14. It is adjusted to supply the amount of oxygen required for complete combustion of the fuel 15. Therefore, in the second combustion chamber 5, the combustible gas contained in the airflow flowing from the first combustion chamber 2 is burned, and the flame generated by this combustion is the axis of the second combustion chamber 5. It is ejected to the outside from the flame ejection port 6 on the other end side in the direction.

Further, in the present embodiment, as shown in FIG. 1A, in the second combustion chamber 5, the tertiary air 28 blown from the tertiary air supply nozzle 13 flows in the circumferential direction along the peripheral wall 12 and gradually becomes the first. 2 Since the flow is toward the downstream side of the combustion chamber 5, a swirling flow 29 is formed inside the second combustion chamber 5.

Therefore, at the place where the swirling flow 29 is formed in the second combustion chamber 5, the vicinity of the axis of the second combustion chamber 5 inside the swirling flow 29 is based on the vicinity of the peripheral wall 12 where the swirling flow 29 is formed. It becomes a relatively negative pressure region.

Therefore, in the second combustion chamber 5, as shown by the alternate long and short dash line in FIG. 1 (a), the second combustion chamber is folded back toward the upstream side, and as described above, the reflux toward the inside of the swirling flow 29 which is a relative negative pressure region. 30 occurs.

In the burner 1 of the present embodiment, the air flow including the high-temperature combustion gas generated when the combustible gas is burned by the tertiary air 28 in the second combustion chamber 5 by the recirculation 30 is introduced into the first combustion chamber 2. It can be supplied toward the heat recirculation region 27 formed near the axis near the upper part. This also keeps the heat reflux region 27 in a hot atmosphere.

The number of tertiary air supply nozzles 13 provided on the peripheral wall 12 of the second combustion chamber 5 in the circumferential direction may be 1 or 2, or may be 4 or more. Further, when a plurality of tertiary air supply nozzles 13 are provided in the circumferential direction of the peripheral wall 12, the intervals between the tertiary air supply nozzles 13 adjacent to each other in the circumferential direction are preferably uniform, but may be uneven. Further, when a plurality of tertiary air supply nozzles 13 are provided on the peripheral wall 12, all the tertiary air supply nozzles 13 may be arranged so as not to be aligned on one plane perpendicular to the axis of the second combustion chamber 5. .. For example, the tertiary air supply nozzle 13 may be provided on the peripheral wall 12 in an arrangement of two stages in the upstream / downstream direction, or a plurality of stages of three or more stages. The posture of the tertiary air supply nozzle 13 is tilted with respect to the plane perpendicular to the axis of the second combustion chamber 5 to the extent that the swirling flow 29 as described above can be formed inside the second combustion chamber 5. It may be tilted or may be inclined from the tangential direction of the peripheral wall 12.

As the ignition burner 16, one that uses LPG, LNG, kerosene, or the like as fuel may be adopted.

As a result, the ignition burner 16 forms a high temperature region in which the biomass fuel 15 can be ignited in the first combustion chamber 2 by burning the fuel at the time of starting the burner 1 of the present embodiment. When the burner 1 of the present embodiment is operated, the fluidized medium 7 of the fluidized bed 3 is heated as the biomass fuel 15 is burned, and the fireproof material constituting the peripheral wall 10 of the first combustion chamber 2 is heated. Will be done.

Therefore, in the first combustion chamber 2, the partial combustion heat of the biomass fuel 15 in the flow layer 3, the combustion heat of the biomass fuel 15 in the swirling flow 24, the flow medium 7 of the flow layer 3, or the first combustion. If the heat possessed by the peripheral wall 10 of the chamber 2 can ignite the newly supplied biomass fuel 15 and start combustion, the ignition burner 16 is turned off during the subsequent operation of the burner 1 of the present embodiment. May be good. By doing so, it is possible to reduce the amount of auxiliary fuel used for the ignition burner 16.

Further, the ignition burner 16 may be used so as to constantly hold the pilot flame during the operation of the burner 1 of the present embodiment. In this case, the biomass fuel 15 sequentially supplied from the fuel supply nozzle 14 into the first combustion chamber 2 can be positively ignited by using the pilot fire held by the ignition burner 16. Even if the biomass fuel 15 has a change in flammability due to a change in particle size, a change in water content, or the like, the operation of the burner 1 of the present embodiment can be continued more stably.

If the ignition burner 16 can start the combustion of the biomass fuel 15 by the primary air 9 and the combustion of the biomass fuel 15 by the secondary air 23 in the first combustion chamber 2, it may be arranged other than shown in the drawing. good. Further, the ignition means 16 is a type of ignition burner 16 that burns any fuel other than fossil fuel if the combustion of the biomass fuel 15 by the primary air 9 and the combustion of the biomass fuel 15 by the secondary air 23 can be started. Further, a type of ignition means other than the use of fuel, such as a type of igniting by utilizing an electric phenomenon such as plasma or spark, may be used.

When the burner 1 of the present embodiment having the above configuration is used, first, the primary air 9 is supplied to the flow layer 3 so that the flow medium 7 is made to flow, and then the secondary air supply nozzle 11 is used. Supply the secondary air 23 into the first combustion chamber 2, the tertiary air 28 is supplied from the tertiary air supply nozzle 13 into the second combustion chamber 5, and the fuel is further ignited with the ignition burner 16. The biomass fuel 15 is supplied from the supply nozzle 14 to the first combustion chamber 2.

As a result, in the first combustion chamber 2, the small particle size particles and the medium particle size particles of the biomass fuel 15 are ignited by the ignition burner 16 in a state of being a two-phase flow well dispersed in the secondary air 23. Rapid combustion is started, and the heat of combustion starts thermal decomposition gasification of the balance of the medium-sized particles of the biomass fuel 15.

Further, in the burner 1 of the present embodiment, the large particle size particles of the biomass fuel 15 that fall without floating in the upward airflow in the first combustion chamber 2 are supported and stirred by the flow layer 3. The combustion heat of the ignition burner 16, the combustion heat of the small particle size particles and the medium particle size particles of the biomass fuel 15, and the primary air 9 promote partial combustion and thermal decomposition gasification.

A part of the combustible gas generated by the partial combustion of the biomass fuel 15 in the first combustion chamber 2 is burned by using the secondary air 23.

Therefore, in the burner 1 of the present embodiment, in the first combustion chamber 2, the airflow containing the high-temperature combustion gas generated by the partial combustion of the biomass fuel 15 and the combustion of the combustible gas is the secondary air along the peripheral wall 10. Accompanied by the swirling flow 24 of 23, it flows upward in the first combustion chamber 2. The airflow flowing upward while swirling in the first combustion chamber 2 generates a reflux 25 toward the inside of the swirling flow 24, and further, the upper part is blocked by the arch-shaped ceiling wall 4, so that the swirling flow 24 An inward return 26 is generated, which forms a heat return region 27 near the upper axis of the first combustion chamber 2.

In the heat reflux region 27, the reflux 26 containing the high-temperature combustion gas is sequentially supplied to maintain the high-temperature atmosphere.

Further, the heat recirculation region 27 is also supplied with heat by the recirculation 30 generated in the second combustion chamber 5 as the tertiary air 28 is supplied to the second combustion chamber 5 as a swirling flow 29.

Therefore, since the burner 1 of the present embodiment can form a heat recirculation region 27 maintained in a high temperature atmosphere near the axis on the upper end side in the first combustion chamber 2, the burner 1 of the first combustion chamber 2 can be formed. The internal temperature can be raised compared to a combustion chamber of a type without a heat return region.

Further, in the first combustion chamber 2, the two-phase flow in which the biomass fuel 15 is dispersed in the secondary air 23 becomes a flow along the peripheral wall 10 as a swirling flow 24, so that the time when the two-phase flow comes into contact with the peripheral wall 10 is time. Can be taken for a long time. Therefore, in a state where the operation of the burner 1 of the present embodiment is stable, it is also possible to promote pyrolysis gasification of the biomass fuel 15 by radiant heat transfer from the heated peripheral wall 10.

Therefore, the burner 1 of the present embodiment can improve the stability of combustion in the first combustion chamber 2 of the biomass fuel 15. Further, in the second combustion chamber 5, the combustible gas generated by the pyrolysis gasification of the biomass fuel 15 can be completely burned.

As described above, the burner 1 of the present embodiment can be operated using the biomass fuel 15 to supply the high-temperature combustion gas and the flame to the outside from the flame ejection port 6.

Further, the burner 1 of the present embodiment is configured to include the flow layer 3, and further, during operation, a heat recirculation region 27 maintained in a high temperature atmosphere can be formed in the first combustion chamber 2, so that it is patented. Biomass fuel 15 having a larger particle size than the biomass fuel used in the conventional burner shown in Document 1, and further, a biomass fuel having a higher water content and ash content and a lower calorific value (true calorific value). Even if it is 15, the accelerated combustion can be performed. Further, the burner 1 of the present embodiment can suppress the possibility that a part of the biomass fuel 15 is discharged to the outside from the flame ejection port 6 as a solid in an unburned state.

The manure of egg-collecting chickens contains a large amount of calcium, has a large amount of ash, and is less combustible than woody biomass, so that it has been difficult to effectively use it as a fuel. On the other hand, since the burner 1 of the present embodiment can promote the combustion of the biomass fuel 15, the biomass fuel 15 derived from the biomass having a lower combustibility than the woody biomass such as manure of a laying chicken. Even so, stable combustion can be performed.

Therefore, the burner 1 of the present embodiment can use the biomass fuel 15 having a wider range of properties than the conventional one, and can effectively use the biomass, which has been considered difficult to use as the conventional fuel, as a fuel. The effect of aiming for biomass can be expected.

Further, since the burner 1 of the present embodiment is provided with the fluidized bed 3 at the bottom of the first combustion chamber 2, it is possible to prevent the unburned biomass fuel 15 from staying in one place for a long time, and ash adheres to the burner 1. Or, the occurrence of clinker can be suppressed. Further, even when the biomass fuel 15 made from biomass containing a large amount of silica (silicon oxide) such as rice husks is used, the effect of suppressing the production of cristobalite can be expected.

By the way, in general, biomass fuel has a slower ignition speed than fossil fuel, so it is better to set it so that the residence time in the combustion chamber is long in order to completely burn it. This residence time is proportional to the superficial velocity determined from the flow path diameter and the exhaust gas flow rate, and in order to obtain the same combustion amount as the fossil fuel burner in a burner using biomass fuel, it is necessary to use fossil fuel. It is necessary to make it larger than the burner and reduce the superficial velocity. Alternatively, in order for the burner using biomass fuel to have the same size as the burner for fossil fuel, it is necessary to reduce the combustion amount to about two-thirds as compared with the burner for fossil fuel.

Therefore, it has been difficult to replace the fossil fuel burner, which is often used in consumer boilers, with a burner that uses biomass fuel of the same size.

On the other hand, according to the test carried out by the present inventors, the burner 1 of the present embodiment has a combustion amount of the same as that of the conventional burner for biomass fuel while keeping the size of the entire apparatus. It was found that it can be improved up to about 1.5 times. Therefore, the burner 1 of the present embodiment can be expected to have an effect of making the burner for fossil fuel, which is often used in civilian boilers, effective when replacing it with a burner using biomass fuel 15.

[Second Embodiment]
5A and 5B show a second embodiment of the burner, FIG. 5A is a schematic front view of cutting, and FIG. 5B is a view taken along the line DD of FIG. 5A.

In FIGS. 5A and 5B, the same reference numerals as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The burner of the present embodiment is shown by reference numeral 1A in FIGS. 5A and 5B, and has an arch-shaped ceiling wall 4 at the top of the first combustion chamber 2 in the same configuration as that of the first embodiment. Instead of the configuration, the configuration is provided with a dome-shaped (hemispherical) ceiling wall 4A.

Further, in the present embodiment, the ceiling wall 4A has a dome shape, so that the ceiling wall 4A is provided above the position where the second combustion chamber 5 is communicated and connected in the peripheral wall 10 of the first combustion chamber 2. ing.

Also in the burner 1A of the present embodiment, the airflow containing the upward component generated in the first combustion chamber 2 is blocked by the ceiling wall 4A above the traveling direction.

Since the ceiling wall 4A has a dome shape, in the first combustion chamber 2, a swirling flow is an air flow in which the velocity of the upward component is larger in the vicinity of the peripheral wall 10 than in the vicinity of the axis of the first combustion chamber 2. When 24 reaches the upper end of the peripheral wall 10, it is guided along the dome-shaped surface of the ceiling wall 4A.

After that, the airflow guided along the surface of the ceiling wall 4A gathers at the top of the ceiling wall 4A. Therefore, in the vicinity of the top of the ceiling wall 4A, as shown by the alternate long and short dash line in FIGS. 5 (a) and 5 (b), Folding from upward to downward, a return 26 toward the inside of the swirling flow 24 is generated as in the first embodiment.

Therefore, also in the burner 1A of the present embodiment, the airflow containing the high-temperature combustion gas is sequentially supplied as reflux 25 and reflux 26 near the axis near the upper part of the first combustion chamber 2, and has a high-temperature atmosphere. The heat reflux region 27 as shown by the alternate long and short dash line in FIGS. 5 (a) and 5 (b) is formed in the same manner as in the first embodiment.

Therefore, the burner 1A of the present embodiment can be used in the same manner as the burner 1 of the first embodiment to obtain the same effect.

The burner of the present disclosure is not limited to each of the above-described embodiments.

The ratio of the radial dimension of the first combustion chamber 2 to the axial dimension shown in each figure, the ratio of the radial dimension of the second combustion chamber 5 to the axial center direction dimension, and further, the first combustion chamber 2 and the second The size ratio of the combustion chamber 5 is for convenience of illustration, and does not reflect the dimensions or the dimensional ratio of the actual machine.

In the burner 1 of the first embodiment, the ceiling wall 4 and the second combustion are considered from the viewpoint of connecting the upper half of the peripheral wall 12 on one end side in the axial direction of the second combustion chamber 5 to the ceiling wall 4 without a step. It is preferable that one end of the chamber 5 in the axial direction has a coaxial center arrangement and the same radius. However, in the burner of the present disclosure, if one end side in the axial direction of the second combustion chamber 5 is communicatively connected to the side of the upper end side of the first combustion chamber 2, the ceiling wall 4 and the second combustion chamber 5 are connected. One end in the axial direction does not have to be in a coaxial center arrangement, and may not have the same radius.

The burner 1A of the second embodiment shows a configuration in which the ceiling wall 4A is provided above the location where the second combustion chamber 5 is communicated and connected in the peripheral wall 10 of the first combustion chamber 2, but the second combustion The chamber 5 may be arranged so as to partially cover the ceiling wall 4A and connected to the peripheral wall 10 of the first combustion chamber 2.

From the viewpoint of forming the recirculation 30 from the second combustion chamber 5 toward the heat recirculation region 27, the burners 1 and 1A of each embodiment have the tertiary air supply nozzle 13 attached to the peripheral wall 12 of the second combustion chamber 5. It is preferable to form the swirling flow 29 in the second combustion chamber 5 by providing it in a posture along the tangential direction. However, the tertiary air supply nozzle 13 may be provided in a posture other than the posture along the tangential direction of the peripheral wall 12 as long as the tertiary air 28 can be supplied to the second combustion chamber 5.

In each embodiment, the first combustion chamber 2 and the second combustion chamber 5 do not have to have a strict cylindrical shape as long as the swirling flows 24 and 29 along the peripheral walls 10 and 12 can be formed.

Of course, various changes can be made without departing from the gist of the present invention.

2 1st combustion chamber 3 Flow layer 4, 4A Ceiling wall 5 2nd combustion chamber 6 Flame ejection port 7 Flow medium 9 Primary air 8 Primary air supply unit 10 Peripheral wall 11 Secondary air supply nozzle 12 Peripheral wall 13 Tertiary air supply nozzle 14 Fuel Supply nozzle 15 Biomass fuel

Claims (5)

A cylindrical first combustion chamber extending in the vertical direction and
The fluidized bed provided on the lower end side of the first combustion chamber and
An arch-shaped or dome-shaped ceiling wall formed at the top of the first combustion chamber,
A second combustion chamber having a cylindrical shape extending in the lateral direction and having one end side in the axial direction connected to the side of the upper end side of the first combustion chamber.
A flame ejection port provided on the other end side in the axial direction in the second combustion chamber, and
A primary air supply unit that supplies primary air that also serves as flow air for the fluidized bed to the fluidized bed.
A secondary air supply nozzle provided on the peripheral wall of the first combustion chamber in a tangential direction and
A tertiary air supply nozzle provided on the peripheral wall of the second combustion chamber,
A burner provided with a fuel supply nozzle for supplying biomass fuel to the first combustion chamber. The burner according to claim 1, wherein the secondary air supply nozzle is provided below the connection position of the second combustion chamber on the peripheral wall of the first combustion chamber. The burner according to claim 1 or 2, wherein the fuel supply nozzle is provided above the installation position of the secondary air supply nozzle on the peripheral wall of the first combustion chamber. The burner according to any one of claims 1 to 3, wherein the tertiary air supply nozzle is provided in a posture along the tangential direction on the peripheral wall of the second combustion chamber. The ceiling wall has an arch shape.
The burner according to any one of claims 1 to 4, wherein the ceiling wall and one end in the axial direction of the second combustion chamber are arranged in a coaxial center and have the same radius.

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