JPH1038217A - Fine powdered coal combustion burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine powdered coal combustion burner which is capable of demonstrating high ignitability even when there are used incombustible coals such as coarse powdered coal having 200 mesh throughput of about 60 to 70% and high fuel ratio coal, and which produces less NOx and less production of incombustible components. SOLUTION: There are disposed concentrically a primary flow passage 11, a secondary flow passage 12, and a tertially flow passage 13 on an outer periphery of a heavy oil nozzle 14. An outlet of the first flow passage is set on the upstream side with respect to the direction A a solid/gas two phase flow than an outlet of the secondary flow passage, on an internal periphery of the tip end of which a reverse fire preventing venturi 15 is provided. The primary flow passage is movable to an upstream side B or a backward flow side C along the central axis X-X of the burner. On a heavy oil nozzle there are provided a fine powdered coal condenser 19 and ant internal periphery flame holder 21. On the other hand, an outer periphery flame holder 20 is mounted on a portion of the outlet of the secondary flow passage in opposition to the internal periphery flame holder. Further, a turning unit 17 of tertiary air is provided on line tertiary flow passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal combustion burner used for a pulverized coal fired boiler or the like.

[0002]

2. Description of the Related Art Since the oil crisis, in Japan, many pulverized coal-fired boilers using coal as a main fuel, whose price is more stable than oil fuel, have been constructed as business-use thermal power generation boilers. The pulverized coal-fired boiler includes a mill for pulverizing the raw coal, a classifier for extracting pulverized coal having a predetermined particle size or less from the pulverized coal powder, a pulverized coal transporter, and a burner for burning the transported pulverized coal. Conventionally, a direct combustion system has been used in which the raw coal is pulverized using a mill with a built-in classifier, and the classified pulverized coal is supplied directly to the burner with carrier air (primary air). Has been put to practical use. In addition, many pulverized coal combustion burners have been developed and put into practical use for the purpose of reducing NOx and for wide-area load (reduction of minimum load).

[0003] As a technique for reducing NOx in a pulverized coal combustion burner, for example, as disclosed in Japanese Patent No. 1750459, combustion air is divided into primary, secondary and tertiary and ignited and burned only with primary air. Secondary air and tertiary air are swirled and blown around the pulverized coal stream to delay the mixing of the combustion pulverized coal stream with the secondary air and tertiary air to facilitate formation of a NOx reduction region in the center of the flame. There is a three-part air system.

[0004] On the other hand, as a technology corresponding to a wide area load, for example, Japanese Patent No. 1907269 and a registered utility model No. 19567
No. 27, a technique for installing a solid-gas separator using a cyclone or a vent pipe outside a pulverized coal combustion burner to burn a pulverized coal stream having a high solids concentration, for example,
No. 4, as disclosed in Japanese Patent Publication No. 4 (1994), a technique for providing a solid-gas separator utilizing a difference in inertia between pulverized coal and conveying air in a pulverized coal combustion burner to burn a pulverized coal stream having a high solids concentration,
For example, as disclosed in Japanese Patent No. 1750459, there is a technique of providing a protrusion called a flame holding ring at the outlet of a pulverized coal combustion burner and forming a swirl recirculation region in the subsequent stream to promote ignition and flame holding of the pulverized coal.

FIG. 13 shows an example of this type of pulverized coal combustion burner conventionally known. In this figure, reference numeral 1 denotes a primary passage through which a solid-gas two-phase flow of pulverized coal and carrier air flows, 2
Is a secondary flow path for conveying air for combustion provided on the outer circumference of the primary flow path 1; 3 is a tertiary flow path for conveying air for combustion provided on the outer circumference of the secondary flow path 2; Denotes a heavy oil nozzle arranged at the center of the burner, 5 denotes a boiler furnace wall, and 6 denotes a wind box provided on the outer surface of the boiler furnace wall 5.

[0006] A venturi 7 for backfire prevention is provided on the inner surface of the primary flow path 1, and a bluff body type flame stabilizing device 8 is attached to the tip of the venturi 7. The secondary flow path 2 communicates with the wind box 6, the inlet of which is disposed on the downstream side in the flow direction of the solid-gas two-phase flow from the setting part of the venturi 7, and the outlet of which is connected to the flame stabilizer 8. Is arranged at a position corresponding to the setting unit. An air swirler 9 is provided in the secondary flow path 2 to supply the swirled secondary air around the combustion flame. The tertiary flow path 3 communicates with the wind box 6, and the outlet thereof is disposed at a position corresponding to the setting section of the flame stabilizer 8. A tertiary air regulator 10 is provided in the tertiary flow path 3 to adjust the supply amount of tertiary air supplied to the outer periphery of the secondary air.

[0007] Pulverized coal conveyed from a mill (not shown) and 1
The solid-gas two-phase flow with the primary air is guided to the primary flow path 1 and is injected from the outlet thereof and burns. At the outlet of the primary flow path 1, a bluff body type flame stabilizer 8 is provided. , Gas-solid two-phase flow and 2
Since the flow of the secondary air is partially obstructed, a high-temperature region called a recirculation region is formed, in which small particles of 30 μm or less are entrained in the downstream portion of the flame stabilizer 8 and burned to generate a high-temperature gas body. Ignition and flame holding of unignited pulverized coal passing near the flame 8 are promoted. The secondary air supplied from the secondary flow path 2 and the tertiary air supplied from the tertiary flow path 2 are swirled around the pulverized coal stream which is ignited and burnt with only the primary air. This delays the mixing of the combustion pulverized coal stream with the secondary air and the tertiary air, so that NOx
A reducing atmosphere is formed, and NOx in the combustion gas is reduced.

According to this burner, the NOx concentration at the outlet of the boiler is set to 150 ppm or less for pulverized coal having a fuel ratio (fixed carbon weight / volatile content weight ratio) of about 1 to 2 and a passing rate of 200 mesh of 80%. It is 200 ppm, and the unburned matter can be 5% or less.

[0009]

Incidentally, in recent years, in relation to pulverized coal-fired boilers, in addition to promoting reduction of NOx, wide-range load operation, and increase in capacity of burners and mills,
Establish a combustion technology for coarse coal with a mesh passing rate of around 60-70% to reduce mill grinding power, and secure a stable supply of raw coal and reduce the fuel ratio to reduce power generation costs. However, it is an important technical problem to establish the combustion technology of flame-retardant coal of 2 to 7.

As a method of accelerating the ignition of flame-retardant coal such as coarse coal or high-fuel-ratio coal, the primary air temperature is set to a normal 80 ° C.
Although it is conceivable to raise the temperature to a higher temperature, the risk of flashback or explosion in the mill and during the transportation from the mill to the burner increases, so that this is not practical at all. Also, 300 ° C to 350 ° C
It is conceivable to mix a part of the secondary air or the tertiary air whose temperature has been increased into the primary flow path. However, in this case as well, ignition in the burner becomes a problem, and the C / A ratio ( Since the ignitability decreases with a decrease in the weight ratio of coal / entrained air), a significant effect cannot be expected to improve the ignitability of the flame-retardant coal as it is. Furthermore, the current pulverized coal burner has a structure in which a reduction region is formed in the vicinity of the burner in order to reduce the NOx of the combustion gas. When burning, the unburned matter at the furnace outlet may be further increased.

The present invention has been made in view of such circumstances, and has as its object to provide high ignitability even when flame-retardant coal such as coarse coal or high-fuel-ratio coal is used as a fuel, and N
An object of the present invention is to provide a pulverized coal combustion burner with a small amount of O _x generation and a small amount of unburned components.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a primary flow path through which a solid-gas two-phase flow of pulverized coal and conveying air flows, and an outer periphery of the primary flow path. In a pulverized coal combustion burner provided with a secondary flow path and a tertiary flow path for supplying combustion air, the solid-gas two-phase flow and the temperature higher than the solid-gas two-phase flow and 400 ° C or lower, and a flashback prevention unit is provided on the inner periphery of the primary flow path on the upstream side with respect to the flow direction of the solid-gas two-phase flow from the mixing unit, and at the burner outlet. A bluff body type flame stabilizer was provided.

More specifically, the outlet of the primary flow path is set upstream of the outlet of the secondary flow path in the flow direction of the solid-gas two-phase flow, and the outlet of the primary flow path is set in the secondary flow path. The solid-gas two-phase flow may be mixed with the secondary air that is the high-temperature air, or the outlet of the primary passage may be set at substantially the same position as the outlet of the secondary passage. And at a temperature higher than that of the solid-gas two-phase flow and 400 ° C. in the primary flow path.
A high-temperature air flow path for flowing the following high-temperature air is provided, and the tip of the high-temperature air flow path is disposed on the downstream side with respect to the flow direction of the solid-gas two-phase flow from the narrowest part of the flashback prevention unit, The solid-gas two-phase flow and the high-temperature air may be mixed in the primary flow path.

When the gas-solid two-phase flow and the high-temperature air are mixed inside the burner, the coal powder in the gas-solid two-phase flow is heated, and a flammable volatile gas component is released from the coal powder. If a bluff body type flame stabilizer is provided at the burner outlet, a recirculation region is formed in the downstream portion as described above, and light particles and gas are entrained. As a fuel, 200 mesh passage rate is 6
When about 0 to 70% coarse coal is used, the amount of pulverized coal that is entrained in the recirculation area downstream of the flame stabilizer decreases because the amount of pulverized coal less than 30 μm is small, but coal powder is used instead of pulverized coal. Since the combustible volatile gas components released by heating are entrained in the recirculation area, a high-temperature gas body is also formed in the recirculation area, and the unburned coarse pulverized coal passing near the flame stabilizer is removed. Ignition flame holding is promoted. Even when high-fuel-ratio coal is used as a fuel, a high-temperature recirculation region can be formed downstream of the flame stabilizer as described above if heating of the coal powder is performed properly, and the ignitability is increased. be able to.

When the solid-gas two-phase flow is brought into contact with high-temperature secondary air or the like, it is easy to ignite in the burner. However, a venturi or a throttle is located upstream of the mixing section on the inner periphery of the primary flow path. By providing the small diameter portion, flashback can be prevented.
Further, similar to the conventional burner, since the secondary air and the tertiary air are blown around the pulverized coal stream which is ignited and burnt only with the primary air, a NOx reduction region is formed in the flame center,
It is possible to reduce the NOx of the combustion gas and decrease the unburned portion.

[0016] In the pulverized coal combustion burner having the above configuration,
The primary flow path or high-temperature air flow path is connected to the burner center axis to adjust the contact and mixing time between the solid-gas two-phase flow and the secondary air, etc., and to ensure the optimal ignitability according to the type of coal and its particle size. Along the flow direction of the solid-gas two-phase flow. That is, in the pulverized coal burner according to claim 2, when the outlet of the primary flow path is moved to the upstream side with respect to the flow direction of the solid-gas two-phase flow and the air for combustion, the solid-gas two-phase flow and the secondary air The longer contact mixing time promotes the release of flammable volatile gases and improves ignitability. Conversely, when the outlet of the primary flow path is moved downstream with respect to the flow direction of the solid-gas two-phase flow and the combustion air,
Since the contact and mixing time between the solid-gas two-phase flow and the secondary air is shortened, the release of combustible volatile gas is suppressed, and ignition in the burner is prevented. Therefore, it is possible to adjust the ignitability according to the type of coal and its particle size. In the pulverized coal burner according to the third aspect, the same effect can be obtained when the hot air flow path is moved.

Further, in the pulverized coal combustion burner having the above configuration, a pulverized coal concentrator may be provided in a downstream portion of the mixing section. With this configuration, the decrease in the C / A ratio in the solid-gas two-phase flow due to the introduction of the high-temperature air can be compensated for by the concentration by the pulverized coal concentrator, so that the ignitability can be sufficiently improved. That is, for example, the primary air ratio (the ratio of the primary air amount to the theoretical combustion air amount) is 0.2, and the secondary air ratio (the ratio of the secondary air amount to the theoretical combustion air amount) is 0.2.
1. In a pulverized coal combustion burner operated at a C / A ratio of 0.4, when the solid-gas two-phase flow supplied in the primary passage is introduced into the secondary passage, the C / A ratio becomes Dilute 2/3.
However, if a pulverized coal concentrator is provided in the secondary flow path, the C / A ratio will be concentrated 1.5 times, so that the local C / A ratio near the flame stabilizer will eventually be reduced to the solid-gas two-phase flow. It can be maintained at substantially the same level as in the case where it is not mixed with the secondary air, and the ignitability is improved as much as the pulverized coal is heated by the high-temperature secondary air.

In the pulverized coal combustion burner having the above-described structure, the bluff body type flame stabilizer provided at the burner outlet is provided with an outer flame stabilizer which interrupts the flow of the outer peripheral portion of the solid-gas two-phase flow and a flow of the inner peripheral portion. And an inner flame stabilizer that blocks the heat. According to such a configuration, the recirculation region can be effectively formed by the downstream portion of the flame stabilizer setting section, so that the ignitability of the flame-retardant coal can be further improved. In this case, the outer flame stabilizer and the inner flame stabilizer can be connected via a connecting member, and the connecting member absorbs thermal stress and vibration stress to prevent the destruction of each flame stabilizer.
It is preferable to use a V-shaped fitting or a U-shaped fitting. Further, it is preferable to provide a rectifying cylinder for rectifying the solid-gas two-phase flow mixed with the high-temperature air on the downstream side of the mixing portion of the solid-gas two-phase flow and the high-temperature air. When a rectifying cylinder is provided on the downstream side of the mixing section, the inner peripheral flame stabilizer can be attached to the burner outlet side of the rectifying cylinder.

Further, in the pulverized coal combustion burner having the above-described configuration, a pulverized coal concentrator is provided in a pipe connecting the pulverized coal production apparatus and the primary flow path, and a solid-gas two-phase flow of pulverized coal and carrier air is provided. Is separated into a concentrated stream having a large amount of solid fuel and a lean stream having a small amount of solid fuel, and a lean stream conveying passage is provided in the primary passage, and the concentrated stream separated by the pulverized coal concentrator is separated from the concentrated stream. The dilute stream separated by the pulverized coal concentrator may be guided to the primary flow path, guided to the dilute flow transfer flow path, and ejected from the burner outlet into the furnace. In this case, 1
Since the C / A ratio of the solid-gas two-phase flow flowing through the next flow path can be increased, the ignitability of the fuel can be further improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to describing an embodiment of a pulverized coal combustion burner according to the present invention, first, a combustion system of a pulverized coal fired boiler using the burner will be described with reference to FIG. The coal stored in the bunker 101 is supplied from the coal feeder 103 to the mill 1 according to the load of the boiler furnace 102.
04 and pulverized by a mill 104 to form pulverized coal.
The generated pulverized coal is classified by a classifier (not shown) attached to the mill 104, and only the pulverized coal having a predetermined particle size or less is conveyed by air for conveyance, and the pulverized coal burner attached to the furnace wall of the boiler furnace 102. 105 is supplied to the primary flow path. The air for pulverized coal transportation is PAF (Primary Air Fan)
) And pressurized to a predetermined temperature (about 80 ° C.) by the heat exchanger 107 and then sent to the mill 104.
On the other hand, the combustion air is FDF (Force Draft Fan) 10
8 to a heat exchanger 109 and heated to about 350 ° C., and then a wind box 1 provided on the furnace wall of the boiler furnace 102.
10 and is supplied to the secondary flow path and the tertiary flow path of the pulverized coal burner 105. The combustion gas generated in the boiler furnace 102 is finally released into the atmosphere through a flue 111, and a part of the combustion gas is discharged into a GRF (Gas Recirculation Fan) 11.
2 and is returned to the GR input duct 113 attached to the boiler furnace 102.

Hereinafter, a first embodiment of a pulverized coal burner according to the present invention will be described with reference to FIGS. In these figures, 11 is a primary flow path through which a solid-gas two-phase flow of pulverized coal and carrier air flows, 12 is a secondary flow path for supplying combustion air, and 13 is a supply of combustion air. A fuel oil nozzle, 15 a venturi for preventing flashback, 16 a secondary air swirler, 17 a tertiary air swirler, 18 a tertiary air regulator, 19 Is a pulverized coal concentrator, 20 is a bluff body type outer flame stabilizer (flame holding ring) provided at the burner outlet, 21 is a bluff body type inner flame stabilizer, 22 is an outer flame stabilizer 20 and an inner flame stabilizer 21 23 is a rectifying cylinder to which the inner peripheral flame stabilizer 21 is attached, and 24 is an inner peripheral flame stabilizer 21 or the rectifying cylinder 2.
Reference numeral 25 denotes a supporting member for supporting the high-temperature air flow path 3.

The pulverized coal combustion burner shown in FIG.
4, a primary flow path 11, a secondary flow path 12, and a tertiary flow path 1
3 is arranged concentrically. The outlet of the primary flow path 11 is 2
A venturi 15 for preventing flashback is provided on the inner periphery of the tip of the next flow path 12 at an upstream side with respect to the flow direction A of the solid-gas two-phase flow from the outlet of the next flow path 12. This primary flow path 11
Can move to the upstream side B or the downstream side C in the flow direction A of the solid-gas two-phase flow along the burner center axis XX. A pulverized coal concentrator 19 is mounted on the outer periphery of the auxiliary fuel supply pipe 14 downstream of the Venturi movement range.
An inner flame stabilizer 21 is provided on the outer periphery of the distal end portion of the auxiliary fuel supply pipe 14 via a support member 24. on the other hand,
An outer flame stabilizer 20 is attached to a portion of the outlet of the secondary flow path 12 which faces the inner flame stabilizer 21. Further, a tertiary air swirler 17 is provided in the tertiary flow path 13.

After passing through the venturi 15, the solid-gas two-phase flow of the pulverized coal and the conveying air supplied to the primary flow path 11
It enters the next flow path 12 and is mixed with the secondary air. The mixed solid-gas two-phase stream is concentrated by the pulverized coal concentrator 19,
Secondary flow path 1 through outer flame stabilizer 20 and inner flame stabilizer 21
The fuel is injected into the boiler furnace from the outlet of No. 2 and burned. The tertiary air swirled by the swirler 17 is blown from the outlet of the tertiary flow path 13 around the burning pulverized coal stream.

As described above, since the secondary air is heated to 300 ° C. to 350 ° C. by the heat exchanger attached to the boiler furnace, the pulverized coal contacted with the high-temperature secondary air rises in temperature and becomes flammable. Release volatile volatile gas components. This volatile gas component is caught in the recirculation area formed in the downstream part of the outer flame stabilizer 20 and the inner flame stabilizer 21 to form a high-temperature gas body. Therefore, according to the pulverized coal combustion burner of this example, even when flame retardant coal such as coarse coal or high-fuel-ratio coal having a 200 mesh passage rate of around 60 to 70% is used as the fuel, the ignitability of the fuel is improved. It is possible to keep good, and to realize high wide-area load characteristics.

In the pulverized coal combustion burner of this embodiment, the primary flow path 11 can be moved along the burner center axis XX to the upstream side B or the downstream side C in the flow direction A of the solid-gas two-phase flow. With such a configuration, the ignitability of the fuel can be appropriately adjusted by adjusting the set position of the primary flow path 11, and it is possible to cope with a wide range of coal types and particle sizes. For example, when flame-retardant coal is used as the fuel, the contact mixing time between the solid-gas two-phase flow and the secondary air can be extended by moving the pulverized coal combustion burner to the upstream side B, and the volatile gas component Since generation can be promoted, ignitability is improved. In addition, once ignition combustion starts, it is mixed with high-temperature secondary air,
The amount of pulverized coal burned before the tertiary swirling flow is mixed increases, and the unburned portion at the furnace outlet can be reduced.
On the other hand, when the flammable coal is used as fuel, the contact mixing time between the solid-gas two-phase flow and the secondary air can be reduced by moving the pulverized coal combustion burner to the downstream side C, and the volatile gas Since the generation of components can be suppressed, ignition in the burner can be prevented.

FIG. 2 shows the unburned rate of the pulverized coal combustion burner according to the present invention in each part from the burner outlet to the furnace outlet, in which the solid-gas two-phase flow and the secondary air are not contact-mixed in the burner. In comparison with pulverized coal combustion burners. As is clear from this figure, the pulverized coal combustion burner according to the present invention has a higher combustion rate in the combustion area near the burner than the conventional burner, and the combustion area near the burner is larger than the conventional burner. In addition, the unburned rate at the burner outlet becomes lower than that of the conventional burner.

FIG. 3 shows the particle size (200
The relationship between the mesh passage rate) and the unburned rate at the burner outlet is shown. As is clear from this figure, the conventional pulverized coal combustion burner cannot reduce the unburned rate at the burner outlet to 5% without using pulverized coal having a 200 mesh passage rate of about 80%. According to the pulverized coal combustion burner according to the above, the unburned rate at the burner outlet can be reduced to 5% by using the pulverized coal having a 200 mesh passage rate of about 60%.

When the gas-solid two-phase flow is mixed with the secondary air, the C / A ratio of the gas-solid two-phase flow is reduced. However, the pulverized coal combustion burner of this embodiment has a venturi around the heavy oil nozzle 14. Fifteen
Since the pulverized coal concentrator 19 is provided on the downstream side of the moving range, the decrease in the C / A ratio in the solid-gas two-phase flow accompanying the introduction of the secondary air is compensated by the pulverized coal concentrator 19. In addition, pulverized coal can be preheated by high-temperature secondary air, so that sufficient ignitability can be realized even when the above-described flame-retardant coal is used as a fuel. In addition, when the solid-gas two-phase flow is brought into contact with the high-temperature secondary air, it becomes easy to ignite in the burner.
Since the venturi 15 is provided on the inner circumference of the outlet of the primary flow path 1,
Flashback can be prevented.

The pulverized coal combustion burner according to this embodiment is characterized in that a solid-gas two-phase flow and high-temperature secondary air are contact-mixed in the burner. Can have another configuration as needed. Hereinafter, modified examples of the pulverized coal combustion burner according to the present embodiment will be listed.

In the pulverized coal combustion burner shown in FIG. 1, an outer flame stabilizer 20 and an inner flame stabilizer 21 are provided at the burner outlet, but the inner flame stabilizer 21 is omitted as shown in FIG. Only 20 may be provided.

In the pulverized coal combustion burner of FIG.
A pulverized coal concentrator 19 is provided on the downstream side of the next flow path 1,
The pulverized coal concentrator 19 can be omitted as shown in FIG.

In the pulverized coal combustion burner of FIG. 1, an outer flame stabilizer 20 and an inner flame stabilizer 21 are provided at the burner outlet, and a pulverized coal concentrator 19 is provided on the downstream side of the primary flow path 11. As shown in FIG. 6, both the inner flame stabilizer 21 and the pulverized coal concentrator 19 may be omitted.

In the pulverized coal combustion burner shown in FIG. 1, a venturi 15 is provided on the inner periphery of the outlet of the primary flow path 11 as a means for preventing flashback, but a pipe constituting the primary flow path 11 as shown in FIG. The same flashback prevention effect can be obtained by narrowing the exit 11a of the road and making it smaller in diameter than the other parts.

In the pulverized coal combustion burner shown in FIG. 1, the inner flame holder 21 is directly connected to the heavy oil nozzle 1 via the support member 24.
4, the outer flame stabilizer 20 and the inner flame stabilizer 21 are arranged without connection. However, as shown in FIG. A rectifying cylinder 23 for rectifying the phase flow is attached, an inner flame stabilizer 21 is attached to a burner outlet side of the rectifying cylinder 23, and the outer flame stabilizer 20 and the inner flame stabilizer 21 are connected by a connecting member 22. You can also. Connecting member 2
2, the flame stabilizer 20 absorbs thermal stress and vibration stress,
It is preferable to use a V-shaped fitting bent in a V-shape, a U-shaped fitting bent in a U-shape, or the like in order to prevent the breakage of 21. Such a configuration can be applied to a case where the pulverized coal concentrator 19 is omitted as shown in FIG. 9, and a throttle for preventing flashback is formed at the outlet 11a of the primary flow path 11 as shown in FIG. It can also be applied to the case.

Hereinafter, a second embodiment of the pulverized coal burner according to the present invention will be described with reference to FIG.

The pulverized coal combustion burner of this embodiment is shown in FIG.
As shown in (a) and (b), the outlet of the primary flow path 11 is
At the same position as the outlet of the next flow path 12,
A high-temperature air flow path 25 through which high-temperature air having a temperature higher than that of the solid-gas two-phase flow and 400 ° C. or less is inserted in the next flow path 11. The tip of the high-temperature air channel 25 is the primary channel 1
1 is located on the downstream side of the narrowest portion of the venturi 15 in the flow direction A of the solid-gas two-phase flow,
In 1, a gas-solid two-phase flow and hot air are mixed. Further, the high-temperature air flow path 25 is configured to be able to move to the upstream side B or the downstream side C with respect to the flow direction A of the solid-gas two-phase flow along the burner center axis XX. Fig. 1 for other parts
Since the burner is the same as the pulverized coal combustion burner according to the first embodiment shown in FIG.

The pulverized coal combustion burner of the present embodiment mixes a solid-gas two-phase flow with secondary air and high-temperature air having the same temperature in the burner, and has a bluff body type flame stabilizer 20, 21 at the burner outlet.
So that the high-temperature air flow path 25 can be moved along the burner center axis XX. Further, a venturi 15 for preventing flashback is located upstream of the high-temperature air blowing portion inside the primary flow path 11. Therefore, the same effect as the pulverized coal combustion burner according to the first embodiment can be exerted.

The pulverized coal combustion burner according to this embodiment is characterized in that a solid-gas two-phase flow, secondary air and high-temperature air at the same temperature are contact-mixed in the burner. The other parts can be appropriately changed in configuration similarly to other configuration examples of the pulverized coal combustion burner according to the first embodiment shown in FIGS. 4 to 10.

Next, a third embodiment of the pulverized coal burner according to the present invention will be described with reference to FIG.

As shown in FIG. 12, the pulverized coal combustion burner according to the present embodiment has a solid-gas two-phase flow of pulverized coal and conveying air in a pipe 31 connecting a pulverized coal production apparatus (not shown) and the primary flow path 11. Is provided with a pulverized coal concentrator 32 for separating the concentrated stream having a large amount of solid fuel and a lean stream having a small amount of solid fuel. A feature is that a road 33 is provided. The concentrated stream separated by the pulverized coal concentrator 32 is led to the primary flow path 11, and is contact-mixed with secondary air in the burner. On the other hand, the dilute stream separated by the pulverized coal concentrator 32 is guided to the dilute flow transfer channel 33 and is jetted into the furnace from the center of the burner. Other parts are the same as those of the pulverized coal combustion burner according to the first embodiment shown in FIG. 1, and corresponding parts are denoted by the same reference numerals and description thereof is omitted.

The pulverized coal combustion burner of the present embodiment can exhibit the same effects as the pulverized coal combustion burner according to the first embodiment, and also has a pipe 31 connecting the pulverized coal production apparatus and the primary flow path 11.
Is provided with a pulverized coal concentrator 32, and the concentrated stream separated by the pulverized coal concentrator 32 is guided to the primary flow path 11, so that the pulverized coal is mixed with the secondary air in the solid-gas two-phase flow. C /
The decrease in the A ratio can be compensated for by the concentration by the pulverized coal concentrator 22, and more excellent ignitability can be realized.

The pulverized coal combustion burner according to this embodiment is provided with a pulverized coal concentrator 32 in a pipe 31 connecting the pulverized coal production device (not shown) and the primary flow path 11. The concentrated stream separated in the above is led to the primary flow path 11, and the other parts are the pulverized coal combustion burners according to the first embodiment shown in FIGS. Similar to the other configuration examples, other configurations can be appropriately adopted. FIG. 12 shows only the case where the solid-gas two-phase flow and the secondary air are contact-mixed, but high-temperature air is jetted into the solid-gas two-phase flow as in the second embodiment. Of course, it can also be applied to pulverized coal combustion burners of the type.

[0043]

As described above, according to the present invention,
Mixing the solid-gas two-phase flow supplied from the primary flow path with the high-temperature air inside the burner to release flammable volatile gas components from the coal powder in the solid-gas two-phase flow, Ignited into the non-ignited coarse coal passing through the vicinity of the flame stabilizer because it was drawn into the recirculation area formed in the downstream part of the bluff body flame stabilizer provided at the burner outlet. Flame holding is promoted, and 200 mesh penetration rate as fuel is 6
Even when flame-retardant coal such as roughly 0-70% coarse coal or high-fuel-ratio coal is used as a fuel, its ignitability is enhanced. In addition, when the gas-solid two-phase flow is brought into contact with high-temperature secondary air, it is easy to ignite in the burner. However, since a small-diameter portion such as a venturi or a throttle is provided on the inner circumference of the outlet of the primary flow path, flashback occurs. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a pulverized coal combustion burner according to a first embodiment.

FIG. 2 is a graph showing the effect of the present invention.

FIG. 3 is a graph showing the effect of the present invention.

FIG. 4 is a configuration diagram of a pulverized coal combustion burner according to the first embodiment in which an inner peripheral flame stabilizer is omitted.

FIG. 5 is a configuration diagram of a pulverized coal combustion burner according to the first embodiment in which the pulverized coal concentrator is omitted.

FIG. 6 is a first view in which the inner flame stabilizer and the pulverized coal concentrator are omitted.
It is a lineblock diagram of a pulverized coal combustion burner concerning an example of an embodiment.

FIG. 7 shows a first example in which a throttle for preventing flashback is provided in the primary flow path.
It is a lineblock diagram of a pulverized coal combustion burner concerning an example of an embodiment.

FIG. 8 is a configuration diagram of a pulverized coal combustion burner according to a first embodiment in which a rectifying cylinder is provided in a primary flow path, and an outer flame stabilizer and an inner flame stabilizer are connected by a connecting member. .

FIG. 9 is a configuration diagram showing another example of the pulverized coal combustion burner according to the first embodiment having a rectifying cylinder.

FIG. 10 is a configuration diagram showing still another example of the pulverized coal combustion burner according to the first embodiment having a rectifying cylinder.

FIG. 11 is a configuration diagram of a pulverized coal combustion burner according to a second embodiment.

FIG. 12 is a configuration diagram of a pulverized coal combustion burner according to a third embodiment.

FIG. 13 is a configuration diagram of a pulverized coal combustion burner according to a conventional example.

FIG. 14 is a combustion system diagram of a pulverized coal-fired boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Primary flow path 11a Restrictor 12 Secondary flow path 13 Tertiary flow path 14 Heavy oil nozzle 15 Venturi 16 Secondary air swirler 17 Tertiary air swirler 18 Tertiary air regulator 19 Pulverized coal concentrator 20 Outer periphery Flame Holder 21 Inner Perimeter Flame Holder 22 Connecting Member 23 Rectifying Cylinder 44 Support Member 25 Hot Air Flow Path 31 Pipe Line 32 Pulverized Coal Concentrator 33 Lean Flow Transport Flow Path

Continued on the front page (72) Inventor Noboru Takayama 3-36 Takaracho, Kure City, Hiroshima Prefecture Inside Babcock Hitachi Kure Laboratory Co., Ltd. (72) Inventor Miki 3-36 Takaramachi Town, Kure City Hiroshima Prefecture Bubcock Hitachi Kure Laboratory Co., Ltd. (72) Inventor Shunichi Tsumura 6-9 Takara-cho, Kure-shi, Hiroshima Babcock-Hitachi Inside the Kure Plant (72) Inventor Hironobu Kobayashi 3-1-1, Sachimachi, Hitachi-shi, Hitachi, Ibaraki Hitachi, Ltd. Inside

Claims (10)

[Claims] 1. A primary flow path through which a solid-gas two-phase flow of pulverized coal and transport air flows, and a secondary flow path and a tertiary flow path provided on an outer periphery of the primary flow path for supplying combustion air. A pulverized coal combustion burner provided with a flow path, wherein a mixing section of the solid-gas two-phase flow and a high-temperature air having a temperature higher than the solid-gas two-phase flow and 400 ° C. or less is provided inside the burner; Pulverized coal characterized in that a flashback prevention unit is provided upstream of the mixing unit on the inner periphery of the passage with respect to the flow direction of the solid-gas two-phase flow, and a bluff body type flame stabilizer is provided at the burner outlet. Burning burner. 2. The pulverized coal combustion burner according to claim 1, wherein an outlet of the primary passage is set upstream of an outlet of the secondary passage with respect to a flow direction of the solid-gas two-phase flow. The solid-gas two-phase flow and the high-temperature air in the secondary flow path;
A pulverized coal combustion burner characterized by mixing with secondary air. 3. The pulverized coal combustion burner according to claim 1, wherein an outlet of the primary flow path is set at substantially the same position as an outlet of the secondary flow path, and the solid flow path is provided in the primary flow path. A high-temperature air flow path through which high-temperature air having a temperature higher than the gas two-phase flow and 400 ° C. or less is provided, and the tip of the high-temperature air flow path is formed by the solid-gas two-phase flow more than the narrowest part of the flashback prevention unit A pulverized coal combustion burner, which is disposed on the downstream side in the flow direction and mixes the solid-gas two-phase flow and the high-temperature air in the primary flow path. 4. The pulverized coal combustion burner according to claim 2, wherein the primary flow path can be moved upstream or downstream with respect to a flow direction of the solid-gas two-phase flow along a burner center axis. A pulverized coal combustion burner characterized by the following. 5. The pulverized coal combustion burner according to claim 3, wherein the hot air flow path can be moved upstream or downstream with respect to the flow direction of the solid-gas two-phase flow along a burner center axis. A pulverized coal combustion burner characterized by the following. 6. The pulverized coal combustion burner according to claim 1, further comprising a pulverized coal concentrator provided downstream of the mixing section. 7. The pulverized coal combustion burner according to claim 1, wherein the bluff body type flame stabilizer interrupts a flow of an outer peripheral flame stabilizer and an inner peripheral portion of a solid-gas two-phase flow. A pulverized coal burning burner comprising an inner flame stabilizer. 8. The pulverized coal combustion burner according to claim 7, wherein the outer flame stabilizer and the inner flame stabilizer are connected via a connecting member. 9. The pulverized coal combustion burner according to claim 1, wherein a rectifying cylinder for rectifying a solid-gas two-phase flow mixed with high-temperature air is provided downstream of the mixing section. A pulverized coal combustion burner characterized in that an inner flame stabilizer is attached to a cylindrical burner outlet side. 10. The pulverized coal combustion burner according to claim 1, wherein a pulverized coal concentrator is provided in a pipe connecting the pulverized coal production apparatus and the primary flow path, and a pulverized coal and a conveying air are provided. The phase flow is separated into a concentrated flow having a large amount of solid fuel and a lean flow having a small amount of solid fuel, and a lean flow conveying flow path is provided in the primary flow path, and the concentrated flow separated by the pulverized coal concentrator is provided. A pulverized coal combustion burner, wherein a stream is guided to the primary flow path, and a dilute flow separated by the pulverized coal concentrator is guided to the dilute flow transfer flow path, and is injected into a furnace from a burner outlet. .