JP7413284B2 - solid fuel burner - Google Patents

Description

The present invention relates to a solid fuel burner that transports and burns solid fuel, and particularly to a solid fuel burner that is suitable for large-sized fuel particles such as biomass particles.

BACKGROUND ART In order to improve the ignitability of solid fuel burners used in boilers such as thermal power plants and to increase flame stability, fuel concentration is locally increased.
In general, in solid fuel burners that use pulverized coal as fuel, a velocity component directed toward the inner wall surface of the nozzle is imparted to the mixed fluid of fuel carrier gas and fuel particles in the fuel nozzle, so that the fuel particles move along the inner wall surface of the nozzle. A fuel concentrator (mechanism) is often installed to enrich the fuel.

For example, in Patent Document 1 (Japanese Patent No. 6231047 specification: JP6231047B2), a first swirler (which gives swirl to the mixed fluid) is installed in the center of the fuel nozzle (sometimes referred to as the primary air nozzle) (9). 6) and a second swirler (7) that imparts a swirl in the opposite direction to the first swirler (6). In the technique described in Patent Document 1, a first swirler (6) applies strong swirl to the mixed fluid to move the solid fuel particles toward the outer circumferential side of the fuel nozzle (along the inner wall surface of the fuel nozzle).
Subsequently, the second swirler (7) applies a swirl in the opposite direction to that of the first swirler (6), thereby weakening the swirl of the mixed fluid.
Therefore, the solid fuel particles are maintained in a concentrated state around the flame stabilizer (10) installed at the burner opening and the tip of the fuel nozzle, even during low load when the concentration of fuel supplied to the burner is low. The ignitability of fuel particles increases and the stability of the flame improves.
At the same time, since the mixed fluid with weakened swirl is ejected from the opening, the mixed fluid does not spread excessively in the furnace, and mixes gently with combustion gas (air) such as secondary air and tertiary air. The production of nitrogen oxides (NOx) is suppressed.

Patent No. 6231047 specification (“0004”, “0048” to “0061”, Figures 1-3, Figure 21) Patent No. 4919844 specification (“0021” to “0023”) Japanese Patent Application Publication No. 2010-242999 (“0033”)

Pelletized wood-based raw materials are often used as fuel for mixed combustion in coal (pulverized coal)-fired boilers for thermal power generation. Here, the pellets are not used as they are, but are crushed and classified in an improved mill (pulverizer/classifier) based on a coal mill (pulverizer), and then the resulting fuel particles are transported. The solid fuel is transported as a gas to a solid fuel burner, and a fluid mixture of fuel particles and carrier gas is supplied to the burner and burned in the same way as pulverized coal.

However, biomass fuel is difficult to pulverize compared to coal, and the mill requires a lot of power to grind it (about 10 times as much power as coal is required to turn wood chips with a particle size of 50 mm into the same particle size as coal), and the current situation is It is difficult to atomize to the same level as pulverized coal. Furthermore, when biomass fuel is pulverized, the possibility of rapid combustion increases, and measures to prevent this are also required. For these reasons, biomass fuel is discharged from the mill in the form of considerably coarser particles than coal (see Patent Document 2; Japanese Patent No. 4919844; Patent Document 3; Japanese Patent Application Laid-Open No. 2010-242999, etc.).
As a result, coarse-grained biomass fuels have lower ignitability than pulverized coal.

On the other hand, when using a fuel with low ignitability, lowering the flow rate of the mixed fluid will make it easier to ignite, but for biomass fuel with large particles, lowering the flow rate to transport it from the crusher to the burner is difficult to achieve in the transport system. This is not practical as it may cause stagnation inside the tank.
Therefore, it is necessary to maintain the flow velocity of the mixed fluid (fuel carrier gas) at a high level until immediately before combustion in the burner.
For this reason, the flow path cross-sectional area of the fuel nozzle is smaller on the upstream side, that is, on the side of the fuel conveyance system (connection with the fuel conveyance piping) connected from the crusher, and on the downstream side, that is, on the furnace opening side, than on the upstream side. It is possible to improve ignitability by increasing the flow rate and reducing the flow velocity.
Here, Patent Document 3 discloses a mechanism for concentrating the fuel in a mixed fluid, which includes a venturi and a fuel concentrator that imparts a velocity component in a direction away from the center of the fuel nozzle. A solid fuel burner is disclosed in which the inner diameter is larger than the inner diameter of the upstream end of the venturi. With this configuration, while maintaining the flow rate of the mixed fluid at a high level in the conveyance system, the flow rate can be reduced just before the fuel particles are combusted in the burner, thereby improving ignitability.
On the other hand, in the solid fuel burner described in Patent Document 3, a curved pipe portion is provided at the upstream side of the fuel nozzle and at the connection portion with the fuel conveyance pipe from the mill to the burner. The mixed fluid flows through a flow path that communicates from the fuel conveyance pipe through the curved pipe section to the straight pipe section of the fuel nozzle.
As a result of the inventors' analysis using simulation models, etc., in such a configuration, the high-speed fluid that passes through the curved pipe part collides with the upper surface and then tends to flow downward as if reflected, especially in the case of a venturi. After concentrating the fuel, if a spindle-shaped fuel concentrator applies a velocity component in a direction away from the center of the fuel nozzle, the fuel particles will be biased in the circumferential direction, and depending on the length settings of each part of the fuel nozzle, It was found that the fluid flow velocity above the fuel nozzle tends to be excessively slow. If the flow velocity becomes too slow, the fuel tends to shift toward the radial center due to its own weight, creating an area with low fuel concentration on the upper radial outside near the fuel nozzle outlet. It was found that the enrichment effect of the fuel may be reduced.

In a solid fuel burner, the present invention provides a method for using fuel provided in a fuel nozzle even when using coarse-grained fuel such as that obtained by pulverizing biomass fuel (such as wood-based raw material into pellets) in a mill. The technical challenges are to ensure the fuel concentration effect of the concentrator and to improve ignitability and flame stability.

In order to solve the above technical problem,
The solid fuel burner of the invention according to claim 1 includes:
a fuel nozzle through which a mixed fluid of solid fuel and its carrier gas flows and opens toward the furnace;
a combustion gas nozzle disposed on the outer peripheral side of the fuel nozzle and ejecting combustion gas;
A solid fuel burner comprising: a fuel concentrator provided on the center side of the fuel nozzle for imparting a velocity component in a direction away from the center of the fuel nozzle to the mixed fluid;
The fuel concentrator has a plurality of vanes that give swirl to the mixed fluid, and each vane is arranged apart from the inner surface of the fuel nozzle without being completely fixed inside the fuel nozzle. , a first swirler disposed on the upstream side in the flow direction of the mixed fluid; and a swirling direction of the plurality of blades, the first swirler being disposed on the downstream side in the flow direction of the mixed fluid with respect to the first swirler; a second swirler whose direction is opposite to that of the first swirler;
A flow path dividing member that divides the flow path of the fuel nozzle into an inner side and an outer side in a cross section of the flow path is provided on the downstream side of the second swirler in the flow direction of the mixed fluid,
The outer diameter of the first swirler is equal to or less than the inner diameter of the upstream end of the flow path dividing member,
supplying the solid fuel concentrated toward the inner circumferential wall of the fuel nozzle in the first swirler to the outside of the flow path partitioning member;
The flow path dividing member has a shape in which an inner diameter at an upstream end is larger than an inner diameter at a downstream end,
The outer diameter of the second swirler is smaller than the inner diameter of the upstream end of the flow path dividing member and larger than the inner diameter of the downstream end .

The solid fuel burner of the invention according to claim 2 is the solid fuel burner according to claim 1 , comprising:
The flow path of the fuel nozzle includes an upstream part whose inner diameter is the same or monotonically increases upstream of the first swirler, and an enlarged pipe part which communicates with the downstream side of the upstream part and whose inner diameter gradually increases. a downstream portion communicating with the downstream side of the expanded tube portion and having a constant inner diameter;
It is characterized by

The invention according to claim 3 is the solid fuel burner according to claim 2 ,
at least a portion of the first swirler is located in an upstream range of the flow path of the fuel nozzle;
It is characterized in that at least a part of the second swirler is located in the downstream region of the flow path of the fuel nozzle.

The invention according to claim 4 is the solid fuel burner according to claim 2 or 3 ,
The outer diameter of each of the swirlers is less than the inner diameter of an upstream portion of the flow path of the fuel nozzle.

According to the invention described in claim 1, by having a fuel concentrator having two swirlers and a flow path dividing member, biomass fuel (woody material made into pellets, etc.) can be used in a solid fuel burner. Even when using coarse-grained fuel such as that obtained by grinding in a mill, the fuel concentrator installed in the fuel nozzle can ensure the fuel concentration effect, improving ignitability and flame stability. can.
In addition, compared to a case without a flow path dividing member, the effect of concentrating fuel particles on the outside of the fuel nozzle (along the inner wall) can be increased, and the effect is less likely to disappear, so the first rotation as a fuel concentrator In the combination of the rotor and the second swirler, there is no need to apply excessive swirl and cancel it. Therefore, the pressure loss of the burner can be reduced. Further, by making the combination of the first swirler and the second swirler as a fuel concentrator more compact, the overall length of the fuel nozzle can be shortened, which also leads to a reduction in the amount of parts used.
In addition, compared to the case where the outer diameter of the blades of each swirler is larger than the inner diameter of the upstream end of the flow path dividing member, it is possible to disperse the carrier gas to the inner circumference while keeping the fuel near the outer circumference. The side fuel enrichment effect can be improved. Moreover, the flow velocity on the gas side of the mixed fluid passing through the flow path dividing member can be further reduced, and ignitability and flame stability can be improved.
In addition, by reducing the inner diameter of the flow path on the outer peripheral side (inner wall side of the nozzle) toward the nozzle opening, the cross-sectional area of the mixed fluid flow between the flow path dividing member and the inner wall of the nozzle is expanded. , the flow velocity of fuel particles is reduced, which can further improve ignitability and flame stability.
Further, on the inner circumferential side (nozzle center side) of the flow path dividing member, the effect of canceling the swirling by the second swirler can be spread throughout the radial direction. Therefore, the mixed fluid with weakened swirl is ejected from the burner opening, and the mixed fluid is not spread excessively in the furnace, and the mixture with combustion gas (air) such as secondary air and tertiary air is gently mixed. The effect of suppressing the production of nitrogen oxides (NOx) can be enhanced.

According to the invention set forth in claim 2 , the fuel nozzle has the same or monotonically increasing straight tube shape on the upstream side of the first swirler, and the expanded tube portion in which the inner diameter gradually increases by communicating with the downstream side thereof; It has a straight pipe-shaped downstream part that communicates with the downstream side of the expanded pipe part and has an inner diameter larger than the upstream side, and in the transport pipe, fuel particles with a large diameter are transported at a high flow rate to avoid stagnation. However, since the cross-sectional area of the flow path is larger on the furnace opening side than on the upstream side, and the flow velocity is reduced, the ignitability and flame stability can be improved while ensuring the fuel concentration effect.

According to the invention set forth in claim 3 , the first swirler effectively concentrates the fuel particles to the outside of the fuel nozzle (along the inner wall), and the second swirler effectively cancels out the swirling. I can do it. That is, in the first swirler, at least a portion of its blades in the longitudinal direction extends over the upstream portion, and it is possible to efficiently impart a radially outward velocity component to the mixed fluid flowing in the upstream portion. can.

According to the fourth aspect of the present invention, the fuel concentrator can be pulled out in the axial direction of the fuel nozzle and removed for maintenance and inspection. Therefore, the workability of maintenance and inspection can be improved.

FIG. 1 is an overall explanatory diagram of a combustion system according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of the solid fuel burner of Example 1. FIG. 3 is a view seen from the direction of arrow III in FIG. FIG. 4 is an explanatory view of the flow path dividing member of Example 1, in which FIG. 4(A) is a side view, FIG. 4(B) is a sectional view taken along the line IVB-IVB of FIG. 4(A), and FIG. 4(C) is a side view. is a diagram corresponding to FIG. 4(B) of modification example 1, and FIG. 4(D) is a diagram corresponding to FIG. 4(B) of modification example 2. FIG. 5 is an explanatory diagram of a comparative example. FIG. 6 is an explanatory diagram of simulation results. FIG. 7 is an explanatory diagram of a boiler (combustion device) equipped with the solid fuel burner of the present invention, and FIG. 7(A) shows the can front side and can rear side of the three stages of solid fuel burners each in the front and rear of the can (boiler). 7(B) and 7(D) are explanatory diagrams of the case where the solid fuel burner of the present invention is installed in which biomass fuel is used in the uppermost stage of the can. 7 (C) and 7 (E) are explanatory diagrams when the solid fuel burner of the present invention is installed, which uses biomass fuel at the top stage on the rear side of the can. It is.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples. In addition, in the following explanation using the drawings, illustrations of members other than those necessary for the explanation are appropriately omitted for easy understanding.

FIG. 1 is an overall explanatory diagram of a combustion system according to a first embodiment of the present invention.
In FIG. 1, in a combustion system (combustion device) 1 according to a first embodiment used in a thermal power plant or the like, biomass fuel (solid fuel) is stored in a bunker (fuel hopper) 4. The biomass fuel in the bunker 4 is pulverized by a mill 5. The pulverized fuel is supplied to a solid fuel burner 7 of a boiler (furnace) 6 through a fuel pipe 8 and combusted. Note that a plurality of solid fuel burners 7 are installed in the boiler 6.

The exhaust gas discharged from the boiler 6 is denitrified by a denitrification device 9. The denitrified exhaust gas passes through the air preheater 10. In the air preheater 10, heat exchange is performed between the air sent from the blower 11 and the exhaust gas. Therefore, the temperature of the exhaust gas is lowered, and the air from the blower 11 is heated. Air from the blower 11 is supplied to the solid fuel burner 7 and the boiler 6 as combustion air through the air pipe 12.
When the exhaust gas that has passed through the air preheater 10 passes through a gas heater (heat recovery device) 13, heat is recovered and the temperature of the exhaust gas is lowered.

The exhaust gas that has passed through the gas heater (heat recovery device) 13 is collected and removed by a dry dust collector 14 to collect dust and the like in the exhaust gas.
The exhaust gas that has passed through the dry dust collector 14 is sent to a desulfurization device 15 to be desulfurized.
The exhaust gas that has passed through the desulfurization device 15 is collected and removed by a wet dust collector 16 to collect dust and the like in the exhaust gas.
The exhaust gas that has passed through the wet dust collector 16 is reheated by a gas heater (reheater) 17.
The exhaust gas that has passed through the gas heater (reheater) 17 is exhausted to the atmosphere from the chimney 18.
Note that the configuration of the mill 5 itself can use various conventionally known configurations, and is described in, for example, Japanese Patent Application Laid-Open No. 2010-242999, so a detailed explanation will be omitted.

FIG. 2 is an explanatory diagram of the solid fuel burner of Example 1.
FIG. 3 is a view seen from the direction of arrow III in FIG.
2 and 3, the solid fuel burner 7 of Example 1 has a fuel nozzle 21 through which carrier gas flows. An opening at the downstream end of the fuel nozzle 21 is provided in a wall surface (furnace wall, water pipe wall) 23 of the furnace 22 of the boiler 6. The fuel nozzle 21 has an elbow 20, which is an example of a bent pipe part, formed at an upstream end in the flow direction of the carrier gas. The elbow 20 is bent so that the flow direction of the mixed fluid is bent by approximately 90 degrees. A fuel pipe 8 is connected to the upstream end of the elbow 20. The fuel nozzle 21 is formed into a hollow cylindrical shape, and a flow path 24 is formed inside the fuel nozzle 21 through which a mixed fluid consisting of solid fuel (pulverized biomass fuel) and carrier gas flows.

An inner combustion gas nozzle (secondary combustion gas nozzle) 26 is installed around the outer periphery of the fuel nozzle 21 to blow combustion air into the furnace 22 . Furthermore, an outer combustion gas nozzle (tertiary combustion gas nozzle) 27 is installed on the outer peripheral side of the inner combustion gas nozzle 26 . Each combustion gas nozzle 26 , 27 blows air from a wind box 28 into the furnace 22 . In the first embodiment, a guide vane 26a is formed at the downstream end of the internal combustion gas nozzle 26, and the guide vane 26a is inclined radially outward with respect to the center of the fuel nozzle 21 (the diameter increases toward the downstream side). . Further, a throat portion 27a extending in the axial direction and an enlarged portion 27b parallel to the guide vane 26a are formed at the downstream portion of the outer combustion gas nozzle 27. Therefore, the combustion air ejected from each combustion gas nozzle 26, 27 is ejected so as to be diffused from the center in the axial direction.

Further, a flame stabilizer 31 is supported at the opening at the downstream end of the fuel nozzle 21 .
In FIGS. 2 and 3, an ignition burner (oil gun) 32 is disposed to penetrate through the center of the flow path cross section of the fuel nozzle 21. As shown in FIG. The ignition burner 32 is supported so as to penetrate through a collision plate 32a supported by the collision plate flange 20a of the fuel nozzle 21.

The fuel nozzle 21 is provided with a straight pipe portion 21a, which is an example of an upstream portion, on the downstream side of the elbow 20 with respect to the flow direction of the mixed fluid. The straight pipe portion 21a is formed into a straight pipe shape having the same cross-sectional area as the flow path 24.
An enlarged portion 21b whose inner diameter (that is, cross-sectional area) increases toward the downstream side is connected to the downstream side of the straight pipe portion 21a. A straight tube-shaped downstream portion 21c having the same cross-sectional area toward the downstream end is connected to the downstream side of the enlarged portion 21b.
In the first embodiment, the angle θ1 that the inner wall of the enlarged portion 21b makes with the extension line of the straight pipe portion 21a is set to 10° to 15°. When θ1 is less than 10°, the length of the fuel nozzle 21 in the axial direction becomes long, and when θ1 exceeds 15°, separation occurs in the flow of the mixed flow, causing stagnation in the flow and causing stagnation. Since there is a problem that fuel tends to accumulate in the center, θ1 is preferably 10° to 15°.

It is not necessarily essential that the shape of the fuel nozzle is connected from the upstream side, such as a straight pipe section 21a (=upstream section), an enlarged section 21b, and a downstream section 21c, such as a straight pipe, an expanded pipe, and a straight pipe. . For example, if a flow path dividing member, which will be described later, is provided, the ignitability and flame stability will be improved, and there may be no problem even if the entire tube is straight.
Throughout the nozzle, even if coarse-grained fuel such as biomass fuel is used, there is no need to excessively strengthen the swirl, and the structure is such that pressure loss and fuel particles adhering to the swirler (34a, 34b) can be avoided. That's fine.

A fuel concentrator 34 is arranged inside the fuel nozzle 21 . A fuel concentrator 34 is supported by the ignition burner 32 . The fuel concentrator 34 has a first swirler 34a on the upstream side and a second swirler 34b on the downstream side.
The first swirler 34a has a plurality of first swirling vanes 34c formed in a spiral shape with the ignition burner 32 as an axis. Further, the second swirler 34b has a second swirler 34d that is inclined in a direction opposite to that of the first swirler 34c (in a reverse spiral shape). The swirl vanes 34c, 34d are not fixed to the inner surface of the fuel nozzle 21, and the outer peripheral ends of the swirl vanes 34c, 34d are spaced apart from the inner surface of the fuel nozzle 21.

Therefore, in the fuel concentrator 34 of the first embodiment, the mixed fluid of fuel and carrier gas is given a swirl toward the outside in the radial direction when passing through the first swirler 34a. Therefore, the fuel is concentrated toward the inner wall surface of the fuel nozzle 21. Then, when passing through the second swirler 34b, a reverse swirl is applied, and the swirl is weakened. Therefore, on the downstream side of the fuel concentrator 34, the mixed fluid has fuel concentrated on the outer peripheral side and has a flow that is close to a straight flow.

When arranging the first swirler 34a and the second swirler 34b inside the fuel nozzle 21 having such an expanded tube shape, the first swirler 34a is placed outside the fuel nozzle 21 (along the inner wall). Regarding fuel particle concentration and the second swirler 34b, the arrangement within the fuel nozzle should be appropriately set so that swirl cancellation is effective and the fuel concentration effect and swirl cancellation effect are less likely to be impaired. is desirable.
As for the first swirler 34a, it is desirable that the blades 34c of the first swirler 34a span the upstream portion (straight pipe portion 21a) in (at least a portion of) the longitudinal direction. Thereby, a velocity component directed outward in the radial direction (towards the inner wall of the nozzle) can be efficiently imparted to the mixed fluid flowing through the upstream portion 21a.

Further, the first swirler 34a has blades 34c whose downstream ends in the longitudinal direction (the axial direction of the fuel nozzle) are the upstream part of the fuel nozzle 21 (the upstream straight pipe part 21a) and the enlarged part 21b (the upstream part). It is preferable that it be located at the same position as the boundary with the expanded pipe section (which communicates with the expanded tube section) or downstream thereof, that is, on the expanded section 21b side. This is to reduce the rebound of fuel particles from the inner wall of the nozzle and enhance the concentration effect. Since it is not necessary to apply excessive swirl, it is possible to suppress the swirl canceling effect by the second swirler 34b without increasing it too much, and the flow path of the fuel nozzle 21 through the two swirlers 34a and 34b can be suppressed. It is also effective in suppressing the increase in pressure loss.
Further, as for the second swirler 34b, it is desirable that the blades 34d thereof (at least partially) extend over the downstream portion 21c (straight pipe portion on the downstream side) in the longitudinal direction. That is, it is desirable that the downstream end of the blade in the longitudinal direction (the axial direction of the fuel nozzle 21) be located on the downstream part 21c (downstream straight pipe part) side of the fuel nozzle 21. Thereby, the second swirler 34b that has a sufficient swirl canceling effect while suppressing pressure loss can be placed at an appropriate distance from the first swirler 34a.

In the first embodiment, the outer diameter _DW1 of the first swirling vane 34c is set to 70% of the inner diameter D1 of the straight pipe portion, as an example, but it is preferably set to 60% to 85%. . If it is less than 60%, the swirl provided will be weak and the fuel enrichment effect will be low. Moreover, if it exceeds 85%, the swirling flow may become too strong.
The outer diameter D _W2 of the second swirl vane 34d is greater than or equal to the outer diameter D _W1 of the first swirl vane 34c (that is, D _W2 ≧D _W1 ). Further, in Example 1, the outer diameter D _W2 is smaller than the inner diameter D1. Furthermore, the outer diameter _DW2 of the second swirling vane 34d is set to 65%, as an example, of the inner diameter D2 of the downstream portion 21c, and is preferably set to 55% to 80%. If it is less than 55%, the effect of canceling the turning by reverse turning becomes low. Moreover, if it exceeds 80%, it becomes difficult to pull out the ignition burner 32 from the fuel nozzle 21 during maintenance. Therefore, in the case of a configuration in which the ignition burner 32 is not pulled out, the outer diameter D _W2 may exceed 80% of the inner diameter D2, or the outer diameter D _W2 ≧ the inner diameter D1.

Further, in the first embodiment, the distance from the downstream end fs of the fuel nozzle 21 to the downstream end of the straight pipe part 21a (=upstream end of the enlarged part 21b) with respect to the flow direction of the mixed flow is L1, and the distance between the fuel nozzle 21 Let L2 be the distance from the downstream end fs of the downstream end fs to the upstream end of the downstream part 21c (=downstream end of the enlarged part 21b), and let L4 be the distance from the downstream end fs of the fuel nozzle 21 to the center of the second swirler 34b. , when the distance from the downstream end fs of the fuel nozzle 21 to the center of the first swirler 34a is L5, in the first embodiment, the following settings are made as an example.
(1) L2=L4
(2) L5-L4=0.7×D2
(3) L5-L1=0.1×D2

Regarding (1), it is also possible to set L2≠L4.
Regarding (2), it was confirmed through a combustion test that 0.7×D2 to 1.3×D2 is preferable. If it is less than 0.7, the swirling of the first swirler 34a will cancel out the swirling of the fuel in the second swirler 34b before it reaches the outer diameter side sufficiently, reducing the fuel enrichment effect. . If it exceeds 1.3, the cancellation of the swirl becomes slow and the swirl remains strong at the downstream end of the fuel nozzle 21, resulting in an increase in NOx.

Regarding (3), it is preferable to set it to 0×D2 to 0.5×D2. If it is less than 0, that is, L5-L1<0, most of the first swirler 34a will be arranged in the enlarged part 21b, and the outer diameter of the first swirler 34c will be smaller than the inner diameter of the fuel nozzle 21. The diameter ratio decreases relatively, and the fuel concentration effect decreases. On the other hand, if it exceeds 0.5, the fuel shifted toward the outer circumferential side by the swirl provided by the first swirler 34a collides with the inner circumferential surface of the fuel nozzle 21 and is reflected radially inward. The fuel becomes more likely to be returned to the atmosphere, reducing the fuel enrichment effect.

That is, in the first embodiment, at least a portion of the first swirler 34a is located within the straight pipe portion (upstream portion) 21a of the fuel nozzle 21. Further, at least a portion of the second swirler 34b is located within the downstream portion 21c of the fuel nozzle 21. Therefore, when arranging the first swirler 34a and the second swirler 34b in the fuel nozzle 21 having an expanded tube shape (enlarged portion 21b), the first swirler 34a is placed outside the fuel nozzle (along the inner wall). ), the second swirler 34b effectively cancels out the swirl, making it difficult for the fuel to be damaged.
The first swirler 34a has its blades 34c hanging over the upstream section (straight pipe section 21a) in (at least a part of) the longitudinal direction, and efficiently handles the mixed fluid flowing through the upstream section 21a in the radial direction. It is possible to give an outward velocity component (toward the nozzle inner wall).

FIG. 4 is an explanatory view of the flow path dividing member of Example 1, in which FIG. 4(A) is a side view, FIG. 4(B) is a sectional view taken along the line IVB-IVB of FIG. 4(A), and FIG. 4(C) is a side view. is a diagram corresponding to FIG. 4(B) of modification example 1, and FIG. 4(D) is a diagram corresponding to FIG. 4(B) of modification example 2.
In FIGS. 2 and 3, a flow path dividing member 36 is arranged downstream of the fuel concentrator 34. As shown in FIG. The flow path dividing member 36 is supported on the inner surface of the fuel nozzle 21 by a support member 37. The flow path dividing member 36 of the first embodiment is formed in a partially conical shape whose inner diameter decreases from the upstream end S1 toward the downstream end S2. Therefore, the flow path dividing member 36 divides the flow path 24 into an outer flow path 24a and an inner flow path 24b.
In FIGS. 3 and 4, the support member 37 is formed into a plate shape extending in the radial direction. A plurality of support members 37 are arranged at intervals in the circumferential direction. In FIG. 3, in the first embodiment, the support member 37 is disposed at a corresponding position between the inner peripheral side protrusions 31a of the flame stabilizer 31.

In FIG. 2, in the solid fuel burner 7 of Example 1, a flow path dividing member 36 is arranged downstream of the fuel concentrator 34. Therefore, in the solid fuel burner 7 of Example 1, the flow path dividing member 36 is disposed on the downstream side where the swirl of the fluid on the nozzle center side is weakened by the second swirler 34b, and the flow path is arranged on the outer peripheral side ( It is divided into two parts: the nozzle inner wall side) and the inner periphery side (nozzle center side). Therefore, most of the fuel concentrated toward the inner peripheral wall of the fuel nozzle 21 by the first swirl vane 34c of the fuel concentrator 34 is supplied to the outer flow path 24a. Therefore, the flow path dividing member 36 hardly obstructs the flow of particles directed outward in the radial direction by the fuel concentrator 34, and the fuel directed outward in the radial direction in the outer flow path 24a is reflected by the inner circumferential wall and returns to the central axis. Even if it tries to move toward the side, it is blocked by the flow path partitioning member 36. Therefore, redispersion of the fuel particles once concentrated on the outer peripheral side (inner wall side of the nozzle) by the first swirler 34a is suppressed, and the concentration effect is maintained up to the vicinity of the nozzle opening.
Therefore, compared to the configuration described in Patent Document 1 which does not include the flow path dividing member 36, the fuel concentration effect can be ensured even when solid fuel particles obtained by pulverizing biomass fuel with poor ignitability are used.

In particular, in the first embodiment, the fuel concentrator 34 is not entirely fixed to the inner surface of the fuel nozzle 21. In a configuration in which the fuel concentrator 34 is supported on the inner surface of the fuel nozzle 21, the supported portion is worn out by collisions of concentrated fuel particles. Therefore, the supporting portion must be made of a special wear-resistant material, which poses a problem of increased costs. On the other hand, in the first embodiment, the fuel concentrator 34 is not supported by the fuel nozzle 21, so there is no part that wears out, and an increase in cost can be suppressed.

In addition, in the solid fuel burner 7 of Example 1, there is no venturi in the fuel nozzle 21, that is, a member that imparts a velocity component of the fuel particles toward the center of the nozzle immediately after passing through the bent pipe portion (elbow 20), and This configuration does not include a fuel concentrator that provides a velocity component in a direction away from the center of the fuel nozzle on the downstream side. That is, the configuration is different from the configuration described in Patent Document 3. In the technology of Patent Document 3, the direction is reversed by first applying a velocity component of the fuel particles toward the center of the nozzle using a venturi, and then applying a velocity component away from the center of the fuel nozzle using a spindle-shaped fuel concentrator. This results in a two-stage concentration effect. For this reason, it is necessary to ensure a certain length of the fuel nozzle, but due to the relationship with other external equipment, piping, and structures, in order to shorten this length, it is necessary to It becomes necessary to set the spread to be rapid. In the curved pipe section on the upstream side of the fuel nozzle, the mixed fluid bends sharply, resulting in uneven distribution of fuel particles within the nozzle cross section. However, if the Venturi throttle or fuel concentrator is set to a steep radial expansion, This bias tends to remain as is on the downstream side.

On the other hand, in the solid fuel burner 7 described in Example 1, the mixed fluid is not influenced by the center of the fuel nozzle 21 in the flow path passing through the curved pipe section, but is moved by the first swirler 34a. Since a velocity component directed away from the center of the fuel nozzle 21 is imparted and the concentration action is completed in one step, the length of the fuel nozzle 21 can be shortened compared to the configuration described in Patent Document 3. If the length of the fuel nozzle 21 can be shortened, there is an advantage that the degree of freedom in installing the burner increases and interference with other equipment outside the furnace, piping, and structures can be avoided. Furthermore, since mixing in the circumferential direction (along the inner wall of the nozzle) is promoted by the effect of swirling, the distribution of fuel particles in the circumferential direction is less likely to be biased, which is effective in improving ignitability and flame stability.

In addition, the solid fuel burner 7 of Example 1 has the flow path dividing member 36, which has a high effect of concentrating fuel particles outside the fuel nozzle 21 (along the inner wall), and the effect is difficult to lose. In the combination of the first swirler 34a and the second swirler 34b as the fuel concentrator 34, there is no need to apply excessive swirl and cancel it, which is effective in reducing burner pressure loss. Further, by making the combination of the first swirler 34a and the second swirler 34b as the fuel concentrator 34 more compact, the overall length of the fuel nozzle 21 can be shortened, which also leads to a reduction in the amount of parts used.

Furthermore, in the solid fuel burner 7 of Example 1, compared to the technology of Patent Document 1, for a mixed fluid containing coarse fuel particles, the fuel particles are concentrated along the inner wall of the fuel nozzle 21 and the burner opening thereof is The holding effect up to the end can be achieved with less turning. That is, fuel particles that have once concentrated along the inner wall of the fuel nozzle 21 are difficult to redistribute toward the center of the nozzle, or the ignitability near the flame stabilizer 31 at the open end is improved due to a reduction in flow velocity, so that the first swirler The strength of the swirling at 34a, that is, the angle of the first swirling blade 34c, etc. can be made relatively gentle. This leads to the fact that the effect of canceling out the rotation in the second swirler 34b can be made relatively gentle. For these reasons, pressure loss within the fuel nozzle 21 can be reduced. Furthermore, even with coarse-grained biomass fuel such as pulverized pellets of wood-based raw materials, local stagnation of the mixed fluid is less likely to occur, so fuel particles can be suppressed from adhering to the swirler (swirl blade).

In the first embodiment, the flow path dividing member 36 is formed in a conical shape, and the flow rate of the fluid passing between the flow path dividing member 36 and the fuel nozzle 21 while passing through the flow path dividing member 36 is decreases. The concentrated fuel is then supplied to the furnace 6 at a reduced flow rate. Therefore, even biomass fuel with low ignitability can ensure ignitability.

Further, in the flow path dividing member 36 of the first embodiment, the cross-sectional area of the outer flow path 24a at the downstream end S2 is smaller than the cross-sectional area of the outer flow path 24a at the upstream end S1 so that the flow velocity of the mixed fluid at the downstream end S2 is lower than the flow velocity at the upstream end S1. It has a conical shape that is larger than the cross-sectional area of the outer flow path 24a. That is, in the first embodiment, the inner diameter D _S1 at the upstream end of the flow path dividing member 36 is larger than the inner diameter D _S2 at the downstream end. With such an inclined shape, solid fuel particles move more easily along the inclined surface than in the case of a cylindrical shape along the axial direction, and are less likely to be deposited on the upper surface. Furthermore, by setting D _S1 > D _S2 , the cross-sectional area of the flow path on the outer peripheral side (nozzle inner wall side) gradually expands toward the nozzle opening, which reduces the flow velocity of fuel particles and improves ignitability and flame. It is more effective in improving the stability of
Note that it is preferable that the inclination angle θ2 at which the flow path dividing member 36 is inclined with respect to the axial direction is 10° to 15°. Note that the reason why it is preferable to set θ2 to 10° to 15° is the same as in the case of θ1.

Further, the inner diameter D _S1 of the upstream end S1 of the flow path dividing member 36 is set to be greater than or equal to the outer diameter D _W1 of the first swirl vane 34c and the outer diameter D _W2 of the second swirl vane 34d. In the case of D _S1 <D _W2 , the carrier gas also flows into the outer peripheral flow path of D _S1 , and the effect of concentrating the particle concentration becomes weak. Therefore, by setting D _S1 ≧D _W2 , the particles flow into the outer circumference and the carrier gas is distributed between the outer circumference and the inner circumference, which has the effect of concentrating the concentration of particles passing through the flow path dividing member 36. From another perspective, since the effect of canceling out the swirling by the second swirler 34b is kept on the inner circumferential side of the flow path (the nozzle center side), the effect of retaining the concentration of fuel particles on the outer circumferential side (the inner wall side of the nozzle) is further increased. can be kept.

Further, in the first embodiment, the inner diameter D _S2 of the downstream end of the flow path dividing member 36 is smaller than the outer diameter D _W2 of the second swirling vane 34d. That is, it is set as D _W2 >D _S2 . By setting D _W2 >D _S2 , the effect of canceling the swirl by the second swirler 34b can be spread over the entire radial direction on the inner peripheral side (nozzle center side) of the flow path dividing member 36. As a result, the mixed fluid with weakened swirl is ejected from the burner opening, and the mixed fluid does not spread excessively in the furnace 6, and is gently mixed with combustion gas (air) such as secondary air and tertiary air. This can enhance the effect of suppressing nitrogen oxide (NOx) production.

Furthermore, the flow path dividing member 36 of the first embodiment is supported by a support member 37 from the inner circumferential wall side of the fuel nozzle 21. If the flow path dividing member 36 is supported from the center axis (ignition burner 32) side, it will separate from the collision plate flange 20a together with the collision plate 32a during maintenance and inspection of the ignition burner 32 and/or the fuel concentrator 34. When drawing out of the furnace, the flow path dividing member 36 and the support member 37 must be separated to pass through the straight pipe portion 21a. That is, there is a problem that the workability of maintenance and inspection work is reduced. On the other hand, in the first embodiment, the flow path dividing member 36 is supported from the inner circumferential wall side of the fuel nozzle 21, and maintenance and inspection of the ignition burner 32 and/or the fuel concentrator 34 can be easily performed.

In the first embodiment, the flow path dividing member 36 and the support member 37 (and the fuel concentrator 34) are connected to the furnace 22 side opening end (downstream end) fs of the fuel nozzle 21 or the furnace 22 wall opening of the solid fuel burner 7. It is installed on the upstream side in the fluid flow direction within the fuel nozzle 21, that is, on the outside of the furnace 22, at a distance from the fuel nozzle 21. More specifically, as shown in FIG. 2, when the distance from the furnace-side opening end fs of the fuel nozzle 21 to the downstream end of the flow path dividing member 36 is L3, the distance L3 is The inner diameter D2 at the side opening end fs is preferably in the range of 0.15×D2 to 1.0×D2. If it is less than 0.15, the flow path dividing member 36 is susceptible to radiation from the furnace.

Therefore, by setting the value to 0.15×D2 or more, the flow path dividing member 36 and the like can reduce the influence of radiation from the furnace (inside the furnace) 22, thereby reducing the possibility that frequent maintenance will be required. Furthermore, it is possible to reduce the risk of ignition even if fuel particles adhere to or accumulate on the upper surface of the flow path dividing member 36, or the risk of ignition within the fuel nozzle 21 due to a tendency to stagnate even if the fuel particles do not adhere or accumulate. This also allows the ignition region to be easily located on the downstream side of the flame stabilizer 31.
Note that if it exceeds 1.0×D2, the downstream end S2 of the flow path dividing member 36 is too far away from each position fs and the furnace wall opening. Therefore, the section after the flow velocity is reduced in the flow path dividing member 36 becomes longer. If the section after the flow velocity reduction becomes longer, there are problems such as an increased possibility that fuel particles will adhere to and accumulate on the wall surface of the fuel nozzle 21, or the fuel nozzle 21 will become longer and the solid fuel burner 7 will become larger.

In the first embodiment, the fuel nozzle 21 has a configuration in which the cross-sectional area of the flow path 24 is the same or monotonically increases across the straight pipe portion 21a, the enlarged portion 21b, and the downstream portion 21c, that is, there is no section where the cross-sectional area decreases. The structure is as follows. If there is a section where the cross-sectional area of the fuel nozzle 21 decreases between the upstream end of the fuel concentrator 34 and the upstream end S1 of the flow path dividing member 36, the flow velocity increases (acceleration) in the section where the cross-sectional area decreases. I will do it. Then, when the flow velocity decelerates at the subsequent position of the flow path dividing member 36, a so-called pulsating flow is formed. In such a case, there will be a region where the flow velocity F is too low, and there is a concern that fuel particles will accumulate and remain.

On the other hand, in Example 1, there is no section where the cross-sectional area of the flow path 24 decreases, no pulsating flow occurs, and the flow velocity F is a low flow velocity where there is concern about fuel particle accumulation and retention. The speed is smoothly decelerated (gradually reduced) without falling into a region. Therefore, in the solid fuel burner 7 of Example 1, the inside of the fuel nozzle 21 is designed such that the flow velocity F does not increase (monotonically decreases or remains the same) and the cross-sectional area monotonically increases or remains the same (does not decrease). It is set.
Therefore, after concentrating the fuel, the cross-sectional area does not decrease and the flow velocity does not increase and decrease repeatedly, so that accumulation and retention of the fuel is reduced, and the fuel is decelerated and supplied to the furnace 6 while remaining concentrated. That is, in the piping of the fuel nozzle 21, large-sized fuel particles are transported at a high flow rate so as not to accumulate, while the flow rate is reduced on the furnace 6 opening side because the cross-sectional area of the flow passage is larger than on the upstream side. This improves ignitability and flame stability.

In FIGS. 2 to 4, the support member 37 of Example 1 is formed into a radial plate shape extending in the radial direction, and has a configuration that does not impede the flow of the mixed fluid as much as possible. In the first embodiment, the supporting member 37 is a single plate-shaped member having the same length in the longitudinal direction as the flow path dividing member 36, but the present invention is not limited to this, and a plurality of plates may be used. Even if it is divided into two parts, it is also possible to use it as a rod-shaped member.
The cross-sectional shape of the support member viewed in the nozzle axial direction is not particularly limited as long as it does not impede the flow, and may be a streamlined wing shape (see FIG. 4(C)), a diamond shape (see FIG. 4(D)), etc. . In the case of a wing shape or a rhombus shape, the flow path is temporarily reduced along the flow direction, so that the concentration of fuel particles is further enhanced and the ignition and flame stability are improved.

Here, if the shape of the support member 37 is a wedge-shaped structure in which the thickness in the circumferential direction is larger toward the downstream side, the wall surface or space facing the opening of the support member to the furnace with respect to the flow direction of the mixed fluid. A vortex is generated in which the mixed fluid flows backwards. Since this planar area receives radiation from the furnace and reaches a high temperature, it is necessary to take measures such as using highly heat-resistant materials and covering the area. There is also a possibility that fuel particles may adhere, grow, or remain due to the generation of the vortex flow described above.

On the other hand, the support member 37 of Example 1 is formed in a plate shape with the thickness direction facing the furnace 22, and when viewed from the opening side of the fuel nozzle 21, a plurality of plate-shaped support members 37 are arranged in a linear manner. Therefore, compared to the configuration described in Patent Document 1, a vortex flow in which the mixed fluid flows backward is less likely to occur, and adhesion, growth, or retention of fuel particles can be suppressed. Further, it is economical because there are fewer measures to take against the high temperature caused by radiation from the furnace 22.
Further, the support member 37 of Example 1 is arranged at a position that does not overlap with the inner peripheral side protrusion 31a of the flame stabilizer 31, and the resistance to the flow of the mixed gas is reduced compared to the case where they overlap.
On the other hand, an example in which the cross-sectional shape of the support member 37 seen in the nozzle axis direction is temporarily reduced along the flow direction, such as a streamlined wing shape or a diamond shape (examples shown in FIGS. 4(C) and 4(D)) In this case, since the protrusion of the flame stabilizer is located downstream of the region where the flow path is once reduced and the fuel particles are concentrated (that is, where distribution has occurred), there is an effect of improving ignition and flame stabilization.

Further, in the first embodiment, regarding the inner diameter of the fuel nozzle (primary nozzle) 21, the inner diameter D2 at the opening (downstream end) is set larger than the inner diameter D1 of the straight pipe portion 21a. On the upstream side of the fuel nozzle 21 (fuel conveyance pipe), in order to prevent fuel particles from adhering and accumulating inside the flow path, it is necessary to maintain the flow velocity of the mixed fluid to a certain degree, but from the viewpoint of ignitability and flame stability. Therefore, it is necessary to sufficiently reduce the flow velocity at the downstream end of the fuel nozzle (primary nozzle) 21. Therefore, in Example 1, the inner diameter D2 at the downstream end is set larger than the inner diameter D1 of the straight pipe portion 21a, and the ignitability and flame stability are improved compared to the case where D1≦D2.

(simulation result)
FIG. 5 is an explanatory diagram of a comparative example.
Next, an experiment (computer simulation) was conducted to confirm the effect of Example 1. In Experimental Example 1, in the configuration of Example 1, the outer diameter D _W1 of the first swirl vane 34c and the outer diameter D _W2 of the second swirl vane 34d were made the same. Furthermore, in Experimental Example 2, the outer diameter D _W2 of the second swirl vane 34d was larger than the outer diameter D _W1 of the first swirl vane 34c. Furthermore, in Comparative Example 1, an experiment was conducted using the configuration shown in FIG. That is, the configuration of FIG. 5 does not include the enlarged portion 21b and the downstream portion 21c of the first embodiment. In addition, in the configuration of FIG. 5, the fuel concentrator is not a swirl vane, but the cross-sectional area of the fuel nozzle is reduced to concentrate the fuel radially inward, and then the diameter increases as it goes downstream supported by the ignition burner. It has a venturi 01 that concentrates fuel on the outside in the radial direction by moving the fuel radially outside with a member that increases.
In the simulation, the distribution (ratio) of fuel in the radial direction was measured at the downstream end of the fuel nozzle 21. The results are shown in FIG.

FIG. 6 is an explanatory diagram of simulation results.
In FIG. 6, in Comparative Example 1, the proportion of fuel in the radially outer region 1 was small, and the proportion of fuel in the radially intermediate region 2 was large. That is, the fuel was not concentrated on the outer peripheral side, and the fuel concentration effect was insufficient.
On the other hand, in Experimental Example 1, the proportion of fuel in region 1 on the outer circumferential side was the highest among all the regions 1 to 3, and the fuel was concentrated on the outer circumferential side. Furthermore, in Experimental Example 2, a result was obtained in which the proportion of fuel in Region 1 was even higher than in Experimental Example 1.

Therefore, even if the flow path dividing member 36 and the fuel concentrator are provided as in Comparative Example 1, the fuel concentrating effect is not sufficient in a configuration that does not include the enlarged portion 21b. In comparison, by adopting a configuration having the enlarged part 21b as in Example 1 (Experimental Examples 1 and 2), the flow velocity is reduced through the enlarged part 21b whose cross-sectional area is enlarged, and the ignitability is improved. Compared to the configuration of Comparative Example 1, the fuel concentration effect is improved and the fuel is concentrated on the outer circumferential side, resulting in further improved ignitability and flame stability.

FIG. 7 is an explanatory diagram of a boiler (combustion device) equipped with the solid fuel burner of the present invention, and FIG. 7(A) shows the can front side and can rear side of the three stages of solid fuel burners each in the front and rear of the can (boiler). 7(B) and 7(D) are explanatory diagrams of the case where the solid fuel burner of the present invention is installed in which biomass fuel is used in the uppermost stage of the can. 7 (C) and 7 (E) are explanatory diagrams when the solid fuel burner of the present invention is installed, which uses biomass fuel at the top stage on the rear side of the can. It is.
In the form shown in FIG. 7(A), biomass fuel is supplied to the uppermost solid fuel burner 7 among the solid fuel burners 7. On the other hand, coal, which is an example of solid fuel, is supplied to the middle and lower solid fuel burners 7'. The coal stored in the bunker 4' is pulverized by the mill 5' to become pulverized coal, which is then supplied to the middle and lower solid fuel burners 7'. In addition, in each stage, a plurality of solid fuel burners 7 are installed along the furnace width direction of the combustion apparatus 1.
The form of the solid fuel burner 7' does not necessarily have to be the solid fuel burner of the present invention described above.

As shown in FIG. 1, when biomass fuel is used, biomass fuel with large particle diameters may fall to the bottom of the furnace without being ignited. If unignited biomass fuel accumulates at the bottom of the furnace, there are problems such as requiring more frequent maintenance and increasing fuel waste.
On the other hand, in the embodiment shown in FIG. 7(A), biomass fuel is used only in the solid fuel burner 7 in the uppermost stage. Therefore, even if unignited biomass fuel is generated in the uppermost solid fuel burner 7, it is likely to be ignited and burned out in the middle and lower solid fuel burners 7' before it falls to the bottom of the furnace. In particular, in the region of the boiler 6 where the solid fuel burners 7, 7' are installed, the temperature tends to increase as the temperature increases upward. Therefore, when biomass fuel is used in the uppermost solid fuel burner 7, unignited biomass fuel is less likely to be generated than when biomass fuel is used in the lower solid fuel burner. Therefore, in the form shown in FIG. 7(A), unignited biomass fuel is less likely to fall to the bottom of the furnace, and waste of fuel can be suppressed.

In addition, in the existing combustion apparatus 1 equipped with three stages of solid fuel burners on each of the front side and the rear side of the can, it is also possible to change so that only the solid fuel burner 7 in the uppermost stage uses biomass fuel. Therefore, the existing combustion device 1 that uses only coal can be easily converted to a combustion device 1 that uses biomass fuel.
Furthermore, as shown in FIGS. 7(B) and 7(C), the number of stages of the solid fuel burners 7, 7' is different before and after the can (or the same number of stages are provided but one is inactive). ), it is also possible to change so that only one solid fuel burner 7 at the top of the can front side or the can rear side uses biomass fuel.

Although FIGS. 1 and 7 illustrate a configuration in which the solid fuel burners 7, 7' are provided in three stages in the vertical direction, the present invention is not limited to this. It is also possible to have a configuration with two or more stages.
At this time, it is desirable that the solid fuel burner 7 that uses biomass fuel be placed in the uppermost stage, but the burner is not limited thereto. It is also possible to have two or more stages, the top stage and the middle stage.
For example, as shown in FIGS. 7(D) and 7(E), in the uppermost stage, one solid fuel burner 7 uses biomass fuel, and the other solid fuel burner 7' uses pulverized coal. It is also possible to do so. That is, it is also possible to configure the solid fuel burner 7 that uses biomass fuel and the solid fuel burner 7' that uses pulverized coal to face each other.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various changes can be made within the scope of the gist of the invention as set forth in the claims. It is possible.
For example, the shape of the support member 37 is not limited to a plate shape, and can be changed to any shape such as a wedge shape, a rhombus shape, or a trapezoid shape.
Further, although the configuration of the two-stage combustion gas nozzles 26 and 27 including the secondary combustion gas nozzle 26 and the tertiary combustion gas nozzle 27 is illustrated, the configuration is not limited to this, and the combustion gas nozzle may be in one stage or three or more stages. It is also possible to do so.

Further, although the fuel concentrator 34 has been exemplified as having two first swirlers 34a and two second swirlers 34b, the present invention is not limited to this. It is also possible to provide three or more, or it is also possible to provide one. Note that even when only one swirler is used, the swirl is weakened in the flow path dividing member 36, so that the mixed fluid after passing through the flow path dividing member 36 is ejected in a state where the swirl is weakened. Furthermore, in consideration of the weakening of the swirl in the flow path dividing member 36, it is also possible to make the performance of the second swirler 34b for imparting reverse swirl lower than the performance of the first swirler 34a for imparting swirl. It is. That is, it is possible to make changes such as shortening the outer diameter of the second swirling vane 34d, decreasing the inclination angle, and shortening the length in the axial direction.

Further, although it is desirable that the fuel nozzle 21 has a downstream portion 21c, the present invention is not limited thereto. It is also possible to adopt a configuration in which the downstream end of the enlarged part 21b becomes the downstream end of the fuel nozzle 21 without having the downstream part 21c. At this time, L2=0, so L2≠L4.

7...Solid fuel burner,
21...Fuel nozzle,
22...furnace,
24...Mixed fluid flow path,
24a...outer flow path,
26, 27... combustion gas nozzle,
34...Fuel concentrator,
34c, 34d...Blade 36...Flow path partitioning member.

Claims (4)

a fuel nozzle through which a mixed fluid of solid fuel and its carrier gas flows and opens toward the furnace;
a combustion gas nozzle disposed on the outer peripheral side of the fuel nozzle and ejecting combustion gas;
A solid fuel burner comprising: a fuel concentrator provided on the center side of the fuel nozzle for imparting a velocity component in a direction away from the center of the fuel nozzle to the mixed fluid;
The fuel concentrator has a plurality of vanes that give swirl to the mixed fluid, and each vane is arranged apart from the inner surface of the fuel nozzle without being completely fixed inside the fuel nozzle. , a first swirler disposed on the upstream side in the flow direction of the mixed fluid; and a swirling direction of the plurality of blades, the first swirler being disposed on the downstream side in the flow direction of the mixed fluid with respect to the first swirler; a second swirler whose direction is opposite to that of the first swirler;
A flow path dividing member that divides the flow path of the fuel nozzle into an inner side and an outer side in a cross section of the flow path is provided on the downstream side of the second swirler in the flow direction of the mixed fluid,
The outer diameter of the first swirler is equal to or less than the inner diameter of the upstream end of the flow path dividing member,
supplying the solid fuel concentrated toward the inner circumferential wall of the fuel nozzle in the first swirler to the outside of the flow path partitioning member;
The flow path dividing member has a shape in which an inner diameter at an upstream end is larger than an inner diameter at a downstream end,
A solid fuel burner characterized in that an outer diameter of the second swirler is smaller than an inner diameter at an upstream end of the flow path dividing member and larger than an inner diameter at a downstream end . The flow path of the fuel nozzle includes an upstream part whose inner diameter is the same or monotonically increases upstream of the first swirler, and an enlarged pipe part which communicates with the downstream side of the upstream part and whose inner diameter gradually increases. a downstream portion communicating with the downstream side of the expanded tube portion and having a constant inner diameter;
The solid fuel burner according to claim 1, characterized in that: at least a portion of the first swirler is located in an upstream range of the flow path of the fuel nozzle;
Solid fuel burner according to claim 2 , characterized in that at least a part of the second swirler is located in the downstream region of the flow path of the fuel nozzle. The solid fuel burner according to claim 2 or 3 , wherein the outer diameter of each of the swirlers is less than the inner diameter of the upstream portion of the flow path of the fuel nozzle.

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