JP2002048306A - Combustion burner and combustion device having the burner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multitubular burner usable as a burner for opposed firing system or corner firing system, and a combustion device having the burner, which prevents attachment of ash to a furnace wall around the burner by burning pulverized coal having poor ash quality, such as brown coal, with promptness and high efficiency in the vicinity of the exit of the burner. SOLUTION: A channel exit for fluid mixture 2 of exhaust gas and coal, and a channel exit for primary air 1 in the channel of the fluid mixture, are provided with guides 9, 8, respectively, for gradually increasing cross-sectional area of the channels. Coal conveyed by the exhaust gas and outer peripheral air are efficiently mixed at a burner exit for accelerating the ignition of the coal. When used as a burner for corner filing system, the taper angles of the guides 9, 8 are rendered to be less than 45 deg., and when used as a burner for opposed firing system, the taper angles of the guides 9, 8 are rendered to be 45 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner for solid fuel combustion such as a furnace, a heating furnace or a hot air generator, and a solid fuel combustion apparatus provided with the burner.
The present invention relates to a combustion burner that enables stable combustion even with low-grade coal containing 30% or more of moisture, and a combustion device provided with the combustion burner.

[0002]

2. Description of the Related Art Energy demand is expected to increase, especially overseas, where low-grade coal having a large amount of moisture and ash and a low calorific value is considered to be mainly used. Among low-grade coals, high-moisture coals such as lignite and sub-bituminous coal have large reserves, but their fuel performance is inferior to that of bituminous coal, such as lower flame temperature and worse flammability. I am concerned. Lignite is a coal that exists mainly in Eastern Europe, and is generally a young coal having an ash content of 20% or more and a moisture content of 30% or more.

[0003] Until now, Japan has imported and used only high quality bituminous coal, so there is little accumulation of technology relating to the combustion of low-grade coal such as lignite. However, while it is expected that demand for electric power in Japan is expected to remain sluggish in the future, it is conceivable that demand for combustion equipment for low-grade coal will increase overseas, so it is necessary to develop combustion technologies that can handle low-grade coal. is necessary.

[0004] Lignite is said to be not so difficult to combat unburned components because of its high volatile content. However, brown coal contains a large amount of water and has a low calorific value as problems, and how to promote ignition and form a stable flame is a key technology for high-efficiency combustion. In addition, lignite has a small calorific value, and thus it is necessary to increase the amount of coal input compared to high-quality coal in order to obtain predetermined combustion energy. Lignite is also a coal whose ash properties include a large amount of calcium (Ca), sodium (Na), etc., so that the amount of ash attached to the furnace wall increases. Therefore, it is necessary to develop a lignite combustion technology that enables high-efficiency combustion and reduces the amount of ash attached to the furnace wall.

[0005] As a burner of the lignite combustion system, a burner is disposed at a corner portion such as the four corners of a furnace, and a burner is disposed at corners such as four corners of the furnace. There are two types of burners: firing.

The burner of the opposed combustion system is devised to promote combustion by a single burner. FIG. 13 shows an embodiment of the opposed combustion system in the prior art of a burner for low-grade coal combustion. Lignite has a lot of moisture, so flue gas drawn from the furnace top (about 1000 ℃, oxygen concentration about 10%)
Dry and crush using A pulverizer called a fan mill is used to pulverize the lignite, and the coal is pulverized by the blades of a rotating fan of the mill. The particle size of the pulverized lignite is 200
The mesh pass value is about 35%, which is considerably coarser than the normally used grain blue coal particle size of 200 mesh pass value of 80%.

The burner shown in FIG. 13 has a multi-tube structure.
A flow path of the primary air 1 is disposed inside a flow path of the mixed fluid 2 of the crushed coal and the exhaust gas provided on the furnace wall, and a flow path of the secondary air 3 is arranged outside the flow path of the mixed fluid 2 in order. And a passage for tertiary air 4. In the flow path of the mixed fluid 2, the mixed fluid 2 is swirled by a swirling means (not shown),
At the burner outlet, primary air 1, secondary air 3 and tertiary air 4
It is devised to promote mixing.

FIG. 14 shows the structure of a conventional multi-tube burner of the opposed combustion type according to the prior art.

When combusting low-grade coal such as lignite using a multi-tube burner of the opposed combustion type, in order to prevent a fire accident, the exhaust gas introduced into the mill is dried and pulverized, and then the exhaust gas is removed. Pulverized coal is transported into the furnace as a transport medium. Although the pulverized coal has a high volatile content, the oxygen concentration around the coal is low. Therefore, the pulverized coal is mixed with the primary air 1, the secondary air 3 and the tertiary air 4 and mixed in the furnace 7 (region where the oxygen concentration is high). Combustion. A flow 12 of combustion air is formed on the outer periphery of the fuel-air mixing zone 7.

FIGS. 15 and 16 show examples of conventional corner firing type burners, in which the flow path of the mixed fluid 2 of coal and exhaust gas and the primary air 1 and the secondary air 3 for combustion are arranged vertically. The burner compartment 22 has a structure that is stacked on the burner. FIG. 16 shows a case where the oil burner 6 for starting the burner is disposed between the pair of combustion primary air 1 flow paths. In a corner firing type burner, the burner compartment 22 may be arranged on a wall surface in the furnace.

The difference between the burner of the corner firing type and the burner of the opposed combustion type is that the burner does not burn coal near the burner outlet, but uses a mixed fluid 2 of coal and exhaust gas and primary air 1 and secondary air 3 for combustion. Each jet has momentum and mixes at the center of the furnace to form a stable fire ball and burn.

In the fire ball, the primary air 1 is mixed with the mixed fluid 2 of coal and exhaust gas to increase the oxygen concentration and promote the ignition of coal. In addition, secondary air 3
Has a particularly important role, and is supported by the stable fireball formation by being ejected from the burner with sufficient momentum.

The method of injecting the primary air 1 and the secondary air 3 in the burner of the corner firing type is different from that of the opposed combustion type, and the primary air 1 and the secondary air 3 are shown in FIG. Fig. 1
The example shown in FIG. 6 is a method of jetting from a box-shaped flow path.

[0014] The burner of the corner firing type is a mixed fluid of coal and exhaust gas 2 when the combustion load of the furnace is reduced.
And the momentum decreases in the furnace, so that the fire ball 26 (see FIGS. 17 and 18) becomes unstable, and stable combustion of coal becomes difficult. As an example of the countermeasure, as shown in FIG. 16, an after-air port 23 is provided on the furnace wall on the downstream side of the burner, and the after-air 21 is injected into the furnace from the air port 23 to stabilize the fire ball 26.

As described above, an important factor for the high-efficiency combustion of pulverized coal using a corner firing type burner is that the mixed fluid 2 of coal and exhaust gas and the primary air 1 and secondary air 3 for combustion are ejected from the burner. The purpose is to make the flow have a penetration force and to form a stable fire ball 26 in the furnace.

Next, ash adhesion in the corner firing system will be described. 17 and 18 show examples of the arrangement of the burner compartment 22 in the furnace horizontal section in the corner firing system. In the example shown in FIG. 17, the compartments 22 are arranged on the four sides of the furnace side wall 5, and in the example shown in FIG. 18, the compartments 22 are arranged at the four corners of the side wall 5 of the furnace.

When the burner compartments 22 are arranged on four sides of the furnace side wall 5 as shown in FIG. 17, the angle α between the jet from the compartment 22 and the furnace side wall 5 becomes four corners of the furnace side wall 5 as shown in FIG. The angle β between the jet of the mixed fluid 2 of the coal and the exhaust gas from the compartment 22 and the combustion air 1, 3 from the compartment 22 and the furnace wall surface 5.
(Α> β). Therefore, the flame generated by the combustion of the jet and the fuel from the burner becomes farther from the furnace side wall 5, and the amount of ash adhered on the furnace wall 5 can be reduced. That is, in order to reduce the amount of ash adhering to the furnace wall 5 using a corner firing type burner, the furnace wall 5
It is important to keep jets and flames as far away as possible.

[0018]

In order to burn pulverized coal efficiently with a single-tube burner of the opposed-combustion type multi-tube type, fuel and air are quickly mixed near the burner outlet to promote ignition of the fuel. This is very important. However, when the ignition region is brought close to the vicinity of the burner outlet, in the case of lignite having poor ash properties, there is a problem that ash adheres to a device such as the furnace wall 5 around the burner.

In order to reduce the amount of ash adhering to the furnace wall 5 using a corner firing type burner, it is necessary to keep the jet and the flame as far away from the furnace wall 5 as possible. When the temperature decreases, a stable fire ball 26 is not formed at the center of the furnace. In particular, when burning low-grade coal such as lignite, a stable fire ball 26 is not formed at the center of the furnace when the combustion load of the furnace is reduced, so that the combustibility of the coal is reduced and the amount of ash deposited on the side wall of the furnace is increased. The above problem also occurs when using a multiple tube type single burner shown in FIG. 13 instead of the burner compartment type burner shown in FIGS. 15 and 16 as a corner firing type burner.

Therefore, an object of the present invention is to provide an opposed-burning type burner which can quickly and efficiently burn even pulverized coal such as lignite having inferior ash properties near the burner outlet to prevent ash adhesion around the burner. It is to provide a burner that can be used and a combustion device provided with the burner. Another object of the present invention is to use a corner firing type burner to form a stable fire ball at the furnace center even when the combustion load of the furnace is reduced, and to prevent ash adhesion on the furnace side wall. And a combustion device provided with the burner. further,
An object of the present invention is to provide a multi-pipe type burner which can be used as a burner of the opposed combustion type or the corner firing type, and a combustion device provided with the burner.

[0021]

The above object of the present invention is attained by the following constitution. That is, the fuel and oxygen concentration 1
A mixed fluid flow path for supplying a mixed fluid composed of a mixed gas of 5% or less (such as combustion exhaust gas, hereinafter simply referred to as exhaust gas), and one or more combustion gases for supplying a combustion gas to the outer periphery of the mixed fluid flow path ( A flow path (hereinafter, referred to as combustion air) (for example, a secondary air to a quaternary air flow path) is disposed on a concentric axis,
Further, in a multi-tube combustion burner in which a primary combustion gas flow path (hereinafter, referred to as a primary air flow path) is arranged on the furnace wall inside the mixed fluid flow path, a mixed fluid flow path outlet, a mixed fluid flow path, This is a combustion burner in which a guide for gradually increasing the cross-sectional area of each flow path is installed at a primary air flow path outlet disposed inside the flow path.

As described above, the guide for gradually increasing the cross-sectional area of the flow path is provided at the outlet of the mixed fluid of the exhaust gas and the coal and at the outlet of the primary air flow path inside the flow path of the mixed fluid. Combustion air is efficiently mixed at the burner outlet to promote coal ignition.

Referring to FIG. 1, the angle (hereinafter, simply referred to as a taper angle) between a flow path outlet guide 9 for the mixed fluid 2 of exhaust gas and coal and a burner center axis of the outlet guide 8 for the primary air 1 is as follows. 45 °, the position on the coordinate axis in the burner central axis direction where the outlet cross-sectional area of the flow path of the primary air 1 starts to gradually increase and the position on the coordinate axis in the burner central axis direction where the outlet cross-sectional area of the flow path of the mixed fluid 2 starts to gradually increase The swirler 19 is installed in the flow path of the primary air 1 at the same position to form a spread flame and perform high-efficiency combustion while ensuring a residence time in the flame.
In addition, a flow path through which the seal air 15 flows along the furnace wall surface is provided at the outermost peripheral portion of the multiple pipes constituting the burner, thereby preventing ash adhesion around the burner.

The above is the case where the burner of the present invention is applied to the burner of the opposed combustion type. However, when the burner of the present invention is applied to the burner of the corner firing type, the flow path of the mixed fluid 2 of the exhaust gas and the coal is used. The taper angle of the outlet guide 9 is less than 45 °, and the position on the coordinate axis in the axial direction where the outlet cross-sectional area of the flow path of the primary air 1 starts to gradually increase is the axial direction where the outlet cross-sectional area of the flow path of the mixed fluid 2 starts to gradually increase. An axial overlapping position on the coordinate axis of the flow path exit guide is set so as to be located on the upstream side of the flow path with respect to the position on the coordinate axis.

In a corner-firing type burner, even when the combustion load of the furnace is small, a stable fire ball is provided in the furnace by a narrowing flame having a momentum in the mixed fluid 2 of exhaust gas and coal and the jet of combustion air. It is possible to form and perform high-efficiency combustion and prevent ash adhesion on the side wall.

[0026]

The brown coal obtained by pulverizing with a fan mill the pulverized blue coal with a 35-200% pass value is obtained by pulverizing a bituminous blue coal with a vertical mill in order to guide the high-temperature furnace exhaust gas to the carrier air. It is much coarser than pulverized coal. Also, lignite, which is easy to ignite, is conveyed to the burner by exhaust gas to prevent fire accidents, and is different from debris blue coal. Therefore, in lignite combustion, how quickly the lignite conveyed by the exhaust gas and the combustion air are mixed at the burner outlet is important for high-efficiency combustion of lignite.

In the present invention, the inertial force of the coarse particles is used to make the cross-sectional area of the flow passage between the flow outlet of the mixed fluid of the exhaust gas and the coal and the outlet of the primary air provided inside the flow passage of the mixed fluid. Providing a guide to gradually increase, the coal carried by the exhaust gas and the combustion air such as secondary air or tertiary air supplied from the outer periphery of the mixed fluid flow path are quickly mixed at the burner outlet,
Promotes ignition.

The jetting direction of the mixed fluid, the jetting direction of the primary air, and the jetting direction of the peripheral air such as secondary air or tertiary air are fixed at 45 ° with respect to the central axis of the burner and swirl into the primary air passage. By installing a vessel, it is possible to form a spreading flame and perform high-efficiency combustion while securing a residence time in the flame.

Further, by providing a flow path for flowing seal air along the furnace wall surface (water wall in the case of a boiler) at the outermost peripheral portion of the multi-pipe constituting the burner, ignition is promoted, and as a result, the flame is burned. Even when approaching the vicinity, ash adhesion around the burner can be prevented.

The multi-tube burner of the present invention can also be used in a corner firing system. At the time of corner firing, if the outlet guide of the mixed fluid flow path of exhaust gas and coal is attached at an angle of less than 45 ° with respect to the burner center axis, the mixed fluid 2 of exhaust gas and coal and the jet of combustion air have momentum. Due to the narrowed flame, a stable fire ball is formed in the furnace, and highly efficient coal combustion can be performed.

At this time, the position in the central axis direction of the burner at which the outlet cross-sectional area of the primary air flow passage starts to gradually increase is the position on the coordinate axis in the burner central axis direction at which the outlet cross-sectional area of the mixed fluid flow passage starts to gradually increase. By setting the position of the guide on the coordinate axis in the burner central axis direction so as to be on the upstream side of the burner, the cross-sectional area of the jet flow of the mixed fluid is narrowed, and the inertia force of the coal jet is increased. These coal jets impinge on the taper (angle <45 °) of the mixed fluid outlet guide and are jetted in the direction of the burner central axis, narrowing and narrowing in the fuel / air mixing region, contributing to the formation of a flame.

In the multi-pipe type burner of the present invention, a mixed fluid flow path of coal and exhaust gas and a combustion air flow path are arranged concentrically, and a burner compartment type in which the flow paths are individually arranged. Compared with the burner, the mixing property of the coal and the combustion air is better, and the stability of the flame can be secured.

Also, by imparting momentum to the jet of the mixed fluid 2 and the combustion air, not only to form a stable fire ball in the center of the furnace, but also to swirl the primary air to promote mixing with coal. In addition, a narrow, narrow flame is formed from the burner outlet, and stable combustion can be secured by the burner alone even when the furnace load is reduced. Also, unlike the opposed-burning type burner in which coal is burned using the burners arranged on the opposed wall surfaces of the furnace, the corner firing type burner narrows and forms a flame, so that the furnace side wall and the flame and mixed fluid 2 In addition, the distance of the jet of combustion air becomes relatively long, and ash deposition on the furnace side wall can be prevented.

[0034]

Embodiments of the present invention will be described with reference to the drawings. The burner shown in FIG. 1 is constituted by a multi-tube consisting of a primary air 1, a mixed fluid of coal and exhaust gas 2, a secondary air 3, and a seal air 15 in this order, with the burner central axis being concentric with the outer periphery. ing. A swirler 19 is installed in the flow path of the primary air 1. A primary air outlet guide 8 and an outlet guide 9 for the mixed fluid 2 are provided at the channel outlet of the primary air 1 and the channel outlet of the mixed fluid 2, respectively, so that the cross-sectional area of the channel gradually increases. The swirler 20 is also provided in the secondary air flow path.

FIG. 2 shows the inclination angles of the primary air outlet guide 8 and the mixed fluid outlet guide 9 with respect to the burner center axis and their respective positions in the center axis direction. The point at which the cross-sectional area of each flow path gradually increases toward the burner outlet is referred to as an angle change point, and an outlet angle change point A of the primary air 1 flow path and an outlet angle change point B of the mixed fluid 2 flow path are provided. Can be In the example shown in FIG. 2, the taper angle a of the outlet guide 8 of the flow path of the primary air 1 and the taper angle b of the outlet guide 9 of the flow path of the mixed fluid 2 are each set to 45 °, and the burners at the outlet angle change points A and B are set. The positions on the coordinate axis in the central axis direction are matched.

FIG. 3 is a view for explaining the combustion promoting mechanism of the burner shown in FIG. As described above, in the combustion of low-grade coal represented by lignite, it is important how to quickly mix coal and combustion air conveyed with exhaust gas having an oxygen concentration of 10% or less at the burner outlet.

The first feature of the burner shown in FIG. 1 is that a guide 8 provided at the outlet of the primary air 1 and a guide 9 provided at the outlet of the mixed fluid 2 are provided. ,
9 is that the taper angles a and b are set to 45 °, respectively, and the positions of the flow path change points A and B on the coordinate axis in the burner center axis direction are matched. At the burner outlet, the primary air 1 is swirled by a swirler 19 to form an internal circulation flow 13 having a high oxygen concentration (see FIG. 3), and guides 8 and 9 on the outside thereof.
Thus, a diffusion flow of the mixed fluid 2 and the secondary air 3 is formed, and a large mixing zone 7 (see FIG. 3) of the coal and the combustion air is formed.

Further, a flow path for the seal air 15 is provided outside the multiple pipes constituting the burner. As shown in FIG. 2, the flow path of the seal air 15 causes the inclination of the outermost peripheral portion of the furnace outlet of the burner with respect to the central axis of the burner. The throat angle d, which is the angle, and the throat angle change point K are determined. At this time, it is desirable that the throat angle d be 45 ° and the throat angle change point K be coincident with the position of the other flow path angle change points A and B on the coordinate axis in the burner axis direction.

In such an arrangement, the primary air 1, the mixed fluid 2 and the secondary air 3 are all jets along the wall surface (water wall) 5 of the furnace, that is, the wall jet where most of the outer air flows along the furnace wall surface 5. The primary air 1, the mixed fluid 2 and the secondary air 3 are used to form a stable flame. Thus, it can be seen that the combustion promoting mechanism of the burner shown in FIG. 3 forms a sufficiently widened flame in the radial direction of the burner as compared with the prior art shown in FIG.

The advantage of the spread flame is that the residence time of the coal particles in the flame is prolonged and the combustion is promoted. The pulverized coal obtained by pulverizing lignite has a 200 mesh pass value of about 35%, unlike bituminous coal. Since the pulverized coal particles obtained by the pulverization are relatively coarse particles, the pulverized coal particles have an inertia force, and the coal ejected from the flow path of the mixed fluid 2 is carried along the tapered guides 8 and 9 to the outer periphery of the flame. , Secondary air 3.

Compared to the prior art burner shown in FIG. 14, it can be seen that the fuel and air mixing zone 7 is formed on the outer periphery of the flame which is more susceptible to radiation, and that ignition is promoted. The coarse-grained lignite also contains some fine coal particles, which are caught in the internal circulation zone 13 having a high oxygen concentration formed in the center of the burner and burnt. A flow 12 of combustion air is formed on the outer periphery of the fuel-air mixing zone 7.

FIG. 4 shows a burner according to another embodiment of the present invention. In FIG. 1, a flow path through which only the secondary air 3 flows as combustion air is provided outside the flow path of the mixed fluid 2, but the burner shown in FIG. 4 is an example in which a plurality of combustion air flow paths are provided. .
FIG. 4 shows an example in which the flow path of the tertiary air 4 is provided on the outer peripheral portion of the flow path of the secondary air 3. Road exit angle change point C
Is provided.

Here, it is preferable that the positions of the flow path angle change points A, B, and C on the coordinate axis in the direction of the burner central axis coincide. In the burner shown in FIG. 4, the swirler 19 is installed in the flow path of the primary air 1, but an example in which the swirler 19 is not installed is shown in FIG. 4 and 5, the burner shown in FIG.
The flow path of the seal air 15 is provided outside the multiple tube constituting the burner in the same manner as the burner shown in FIG.

FIG. 6 shows how ash adheres around the burner when the flow path of the seal air 15 is not provided.

When the fuel discharged from the burner is ignited in the furnace, the flame spreads and forms a flame. However, when the ignition is further promoted, the flame approaches the burner outlet and the gas flow 17 that carries the ash particles to the furnace side wall 5 is formed. Are formed on the outer periphery of the combustion air flow 12. The ash particles are easily transported to the furnace side wall 5 by the gas flow 17, and the ash adhesion layer 1 is formed on the furnace wall 5 around the burner.
You can do 6.

On the other hand, FIG. 7 shows a state around the burner when the flow path of the seal air 15 is installed. When the seal air 15 flows, the flow 1 of the seal air along the furnace side wall 5 is shown.
The formation of the ash adhesion layer 16 on the furnace wall 5 around the burner can be prevented even when the flame 8 approaches and the flame approaches the burner outlet.

Although the case where the burner of the present invention is used in the opposed combustion system has been described above, the burner of the present invention can also be used in the corner firing system. FIG. 8 shows an embodiment in which the burner of the present invention is used in a corner firing system.

The burner shown in FIG. 8 is different from the burner shown in FIG. 1 in that the change point A of the taper angle (taper angle a = 45 °) of the outlet guide 8 of the primary air flow path on the coordinate axis in the burner center axis direction. The position is located on the upstream side of the flow path (upstream of the burner) from the position on the coordinate axis in the burner center axis direction of the angle change point B of the outlet guide 9 of the mixed fluid flow path, and the flow path exit guide of the mixed fluid 2 9 is less than 45 °.

FIG. 9 shows the taper angles a and c of the flow path outlet guides 8 and 9 of the burner shown in FIG. 8 and the positions of the flow path angle changing points A and B in the burner central axis direction. FIG. 10 is a view for explaining a mechanism for promoting coal combustion by the burner shown in FIG.

Generally, when a burner is used in the corner firing method, the tangential momentum of the jet of the mixed fluid 2 of coal and exhaust gas is increased to form a stable fire ball 26 (FIGS. 17 and 18). It is important.
Therefore, unlike the case where a burner is used in the opposed combustion system, it is desirable that a narrow and narrow narrow flame is formed.
The cross-sectional area of the jet flow of the mixed fluid 2 is narrowed by setting the flow channel angle change point A of the primary air 1 on the upstream side of the flow path (burner upstream side) from the angle change point B of the mixed fluid 2 flow path. , The inertia of the coal jet increases. These coal jets impinge on the taper (angle <45 °) of the mixed fluid outlet guide 9 and are jetted in the direction of the burner central axis, forming a narrow and narrow flame in the fuel and air mixing region 7.

Since the swirling of the outer air such as the secondary air 3 and / or the tertiary air 4 also affects the flame shape, the outer peripheral air such as the secondary air 3 and / or the tertiary air 4 is required to form a narrow and narrow flame. The swirl number of the air is desirably 1 or less.

Next, the point that the burner of the present invention is superior to the compartment type burner shown in FIGS. 15 and 16 will be described. What is important in the corner firing type burner is to form a stable fire ball in the furnace, and therefore, it is necessary to increase the tangential momentum of the jet of coal or combustion air. Therefore, in the corner firing method, ignition near the burner is considered to be poor. In the corner firing type burner of the present invention, a narrow and long narrowing flame is formed. At this time, a swirler 19 installed in the flow path of the primary air 1 is used to mix the primary air 1 and the mixed fluid 2 of coal and exhaust gas.
Is promoted, so that not only a fire ball but also a burner alone can be efficiently burned.

FIG. 11 shows a burner according to another embodiment of the present invention, in which the tapered angle c of the mixed fluid outlet guide 9 is zero.
°, the primary air flow path outlet end is located upstream of the burner upstream of the mixed fluid 2 flow path outlet.

FIG. 12 shows an example of a burner in which a swirler is not installed in the primary air flow path. In this case, the reason why the flame is narrowed by a corner firing type burner in order to enhance the effect of preventing ash adhesion to the furnace wall 5 will be described.

As shown in FIG. 19, when a spreading flame 24 is formed in a corner firing type burner,
Since the distance between the flame 24 and the furnace side wall 5 is reduced, the ash adhesion layer 16 is easily formed on the furnace side wall. On the other hand, as shown in FIG. 20, when the flame 25 is narrowed by the burner and the flame 25 is formed, the distance between the furnace side wall 5 and the flame 25 increases, so that ash adhesion to the furnace side wall can be prevented.

That is, in the burner according to the embodiment of the present invention, the guides 8 and 9 are provided at the outlet of the primary air flow path and the outlet of the mixed fluid flow path, respectively, and further, the swirler 19 is provided in the primary air flow path. This promotes the mixing of the combustion gas with the coal carried by the exhaust gas, the water content is 20% or more, and the ash content is 30%.
% Or more low-grade coal enables high-efficiency combustion.

Guides 8, 9, and 14 are provided in each of the primary air flow path, the mixed fluid flow path, and the outer combustion air flow path.
By changing the taper angle of each of the guides 8, 9, and 14 and the position on the coordinate axis in the direction of the burner central axis at the point where the flow path angle is changed, the mixing area of coal and combustion air is changed to the outside and inside of the flame. Since the spread of the flame can be adjusted, it can be used both as an opposed type burner and a corner firing type burner.

Further, in the burner according to the above-described embodiment of the present invention, an increase in the amount of ash deposited around the burner and on the furnace side wall 5 can be prevented even for low-grade coal having poor ash properties.

The effects of the above embodiment of the present invention are summarized as follows. (1) Coal conveyed by exhaust gas and combustion air can be quickly mixed at the burner outlet to promote ignition. (2) A large internal circulation area 13 can be formed on the burner center axis extension line in the furnace by attaching a guide 8 having a gradually increasing cross-sectional area to the primary air flow path outlet and further turning the primary air 1. (3) In the opposed-burning type burner, the coal and the surrounding air are spread at an angle of 45 ° with respect to the burner center axis and are jetted to promote the mixing of the coal and the combustion air, and to spread with a long residence time. High efficiency combustion can be realized by forming a flame.

(4) An increase in the amount of ash adhering to the furnace side wall 5 around the burner is provided by providing a flow path through which the seal air 15 flows along the furnace side wall 5 on the outer periphery of the multiple tube constituting the opposed combustion type burner. Can be prevented.

(5) In the burner of the corner firing type, the jet of the mixed fluid 2 of coal and combustion air forms a long and narrow flame having momentum in the direction of the central axis of the burner to stabilize in the furnace. Fire ball 2
6 can be formed. (6) In the corner firing method, by forming a thin and long flame, the distance between the furnace side wall 5 and the jet of fuel or the like can be increased, and an increase in the amount of ash adhered to the furnace side wall 5 can be prevented. (7) In both the opposed combustion type and the corner firing type burners, stable combustion can be maintained even when the combustion load of the furnace is reduced.

[0062]

The burner of the present invention can use low-grade coal for combustion, and when low-grade coal is applied to a counter-burning type burner, achieves high-efficiency combustion and is suitable for a corner firing type burner. Even when applied, stable combustion in the furnace is possible, and in any of the above-described burners, it is possible to prevent an increase in the amount of ash adhering to the furnace wall around the burner and further reduce the furnace combustion load. Also, stable coal combustion can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a burner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a guide taper angle of the burner of FIG. 1 and a passage angle change point in a burner center axis direction.

FIG. 3 is a diagram illustrating a combustion promotion mechanism of the burner of FIG. 1;

FIG. 4 is a cross-sectional view of the burner according to the embodiment of the present invention.

FIG. 5 is a sectional view of a burner according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating how ash adheres to a furnace wall around a burner when there is no seal air.

FIG. 7 is a diagram illustrating a state of ash adhesion around a burner when there is seal air.

FIG. 8 is a cross-sectional view of an embodiment in which the burner of the present invention is applied to a burner of a corner firing system.

9 is a diagram showing a positional relationship between a guide taper angle of the burner of FIG. 8 and a flow path angle change point in a burner center axis direction.

FIG. 10 is a diagram illustrating a combustion promotion mechanism using the burner of FIG. 8;

FIG. 11 is a sectional view of a burner according to the embodiment of the present invention.

FIG. 12 is a sectional view of a burner according to the embodiment of the present invention.

FIG. 13 is a sectional view of a conventional burner for low-grade coal combustion.

14 is a diagram illustrating a combustion promotion mechanism of the burner in FIG.

FIG. 15 is a front view of a conventional corner firing type burner.

FIG. 16 is a front view of a conventional corner firing type burner.

FIG. 17 is a plan view showing an example in which burner compartments are arranged on four sides of a furnace side wall.

FIG. 18 is a plan view showing an example in which burner compartments are arranged at four corners of a furnace side wall.

FIG. 19 is a plan view showing a relationship between a spreading flame and ash adhesion on a furnace side wall in an example in which burner compartments are arranged on four sides of a furnace side wall.

FIG. 20 is a plan view showing the relationship between narrowing flame and furnace side wall ash adhesion in an example in which burner compartments are arranged on four sides of a furnace side wall.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Primary air 2 Mixed fluid of coal and exhaust gas 3 Secondary air 4 Tertiary air 5 Furnace side wall, wall (water wall) 6 Oil burner 7 Mixing area of coal and combustion air 8 Primary air outlet guide 9 Mixed fluid outlet guide 12 Combustion Air flow for internal use 13 Internal circulation flow 14 Tertiary air flow path exit guide 15 Seal air 16 Adhesive layer of ash 17 Gas flow carrying ash particles to furnace side wall 18 Seal air flow along water wall 19, 20 Swirler 24 Spread flame 25 Narrow Flame 26 fireball

Continuing on the front page (72) Inventor Shunichi Tsumura 6-9 Takaracho, Kure-shi, Hiroshima Prefecture Inside the Babcock Hitachi Kure Factory (72) Inventor Kenji 6-9 Takaracho, Kure-shi, Hiroshima Prefecture Babcock Hitachi Kure Business, Ltd. In-house F term (reference) 3K065 QB03 QB09 QB11 QB19 QC02 TA15 TB01 TC03 TD07 TE01 TE10 TH12 TJ03 TJ06 TL02

Claims (10)

[Claims] 1. A mixed fluid flow path for supplying a mixed fluid comprising a fuel and a mixed gas having an oxygen concentration of 15% or less, and one or more combustion gas flow paths for supplying a combustion gas to an outer periphery of the mixed fluid flow path. A multi-tube combustion burner, which is arranged on a concentric axis, further has a primary combustion gas flow path inside the mixed fluid flow path, and these flow paths are provided on the furnace wall surface, comprises a mixed fluid flow path. A combustion burner, wherein a guide for gradually increasing the cross-sectional area of each flow path is provided at a flow path outlet and a primary combustion gas flow path outlet disposed inside the mixed fluid flow path. 2. The combustion burner according to claim 1, wherein a guide for gradually increasing the cross-sectional area of the outlet of the passage is provided in at least one of the air passages for combustion other than the gas passage for primary combustion. 3. The combustion burner according to claim 1, further comprising a sealing gas flow path for flowing gas along the furnace wall from the burner outlet further outside the outermost combustion gas flow path. 4. The combustion burner according to claim 1, further comprising a swirler for swirling the gas in the primary combustion gas passage. 5. An angle between each of a guide provided at an outlet of a primary combustion gas flow path and a guide provided at an outlet of a mixed fluid flow path and a central axis of a burner is 45 °. Item 2. A combustion burner according to Item 1. 6. A position on a coordinate axis in the direction of the burner central axis at which the outlet cross-sectional area of the primary combustion gas flow path starts to gradually increase, and a position on a coordinate axis of the burner central axis direction at which the outlet cross-sectional area of the mixed fluid flow path starts to gradually increase. 6. The combustion burner according to claim 5, wherein? 7. The combustion burner according to claim 1, wherein the angle between the mixed fluid flow path exit guide and the burner center axis is less than 45 °. 8. The position on the coordinate axis in the direction of the burner central axis at which the outlet cross-sectional area of the primary combustion gas flow path starts to increase gradually is the position on the coordinate axis of the burner central axis direction at which the outlet cross-sectional area of the mixed fluid flow path starts increasing. The combustion burner according to claim 7, further upstream of the fluid flow path. 9. A combustion apparatus, wherein the combustion burners according to claim 5 are arranged on a pair of furnace walls facing each other. 10. A combustion apparatus characterized in that the combustion burners according to claim 7 are arranged at corners of a furnace side wall, respectively.