JPH11304116A - Solid fuel burner and burning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a combustion state optimal for NOx reduction at the time of burning pulverized coal without causing deficiency of air supply to the central part of flame of oil combustion even when the ambient temperature in a furnace is low. SOLUTION: Mixture fluid 1 of pulverized coal and carrying air is fed to a primary channel and secondary and tertiary airs 6, 9 are fed to the outer circumference thereof wherein spreading of the tertiary air 3 is changed at the time of burning pulverized coal and at the time of burning oil by means of a guide plate 11. At the time of burning pulverized coal, flow rate of air 23 is increased by shifting a sleeve 21 to the wind box 5 side and spreading of the tertiary air 3 is maximized by means of the guide plate 11 thus forming an excess fuel region required for low NOx combustion in the center of flame. At the time of burning pulverized oil through an oil burner 12, interval between the guide plate 11 and the sleeve 21 is limited to suppress spreading of the tertiary air 3 and air supply to the central part of flame is accelerated in order to suppress production of gas phase deposition carbon thus ensuring optimal combustion of both coal and oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a combustion device,
The present invention relates to a solid fuel combustion burner which enables optimal combustion for both liquid fuel combustion and powder solid fuel combustion, and a method for burning the burner.

[0002]

2. Description of the Related Art FIG. 8 shows an example of the structure of a conventional pulverized coal combustion burner. A mixed fluid 1 of pulverized coal of fuel and carrier air (primary air) is supplied to a combustion furnace 4 through a primary nozzle 2. An L-shaped flame stabilizer 3 is arranged at the tip of the primary nozzle, and a boiler flame is formed from near the burner by the effect of the circulation vortex of the mixed fluid 1 formed on the downstream side. Primary nozzle 2
Combustion air (secondary air 6 and tertiary air 9) is supplied from a wind box 5 to the outer periphery of.

[0003] The secondary air 6 and the tertiary air 9 are spread outward by the respective swirling generators 7 and 10, so that a so-called excess fuel condition in which there is a shortage of air at the center of the flame is formed. Optimal conditions for reducing NOx are set. The tertiary air 9 is further expanded outward by a guide plate 11 for partitioning the flow of the secondary air 6 and the tertiary air 9,
A so-called excess fuel condition in which the center of the flame has a shortage of air is formed, and an optimal combustion state for reducing NOx during pulverized coal combustion is obtained. At the start of burner combustion, the start of combustion of pulverized coal is urged by using the oil burner 12 arranged at the center of the primary nozzle 2.

[0004]

The low NOx burner according to the prior art has an optimum structure for reducing NOx in pulverized coal combustion. However, guide plate 1
By expanding the tertiary air 9 by 1, when the ambient temperature in the combustion furnace 4 is low, such as when the boiler is started, the air flow rate at the center of the flame becomes insufficient for oil combustion using the oil burner 12, In some cases, the amount of phase precipitated carbon (soot) is increased.

SUMMARY OF THE INVENTION An object of the present invention is to provide a combustion furnace having a low atmosphere temperature even when the ambient temperature is low, without causing a shortage of the air flow rate at the center of the flame for oil combustion, and a low N during combustion of pulverized coal.
An object of the present invention is to provide a pulverized coal combustion burner capable of obtaining an optimal combustion state for Oxification.

[0006]

The above object of the present invention is attained by the following constitution. (1) A primary nozzle for introducing a powdered solid fuel and a gas carrying the fuel into a combustion furnace, and a liquid fuel nozzle for injecting a liquid fuel inside the primary nozzle are arranged outside the primary nozzle. An outer peripheral flow path for supplying a plurality of oxygen-containing gases for combustion, and a guide plate for expanding the direction of the oxygen-containing gas for combustion outward with respect to the central axis of the burner at the end of a single or a plurality of the outer peripheral paths. In the solid fuel combustion burner where
A solid fuel combustion burner characterized in that during combustion of solid fuel, the oxygen-containing gas for combustion in the outer peripheral passage is spread outward, and when burning liquid fuel, the oxygen-containing gas for combustion in the outer peripheral passage is suppressed from spreading outward. Burning method.

(2) Based on the results of confirming both the liquid fuel combustion state and the solid fuel combustion state, the spread of the oxygen-containing gas for combustion is adjusted manually or automatically to an optimum state for both fuels. 2. The method for burning a solid fuel combustion burner according to claim 1, wherein the state is fixed.

(3) A primary nozzle for charging the solid fuel powder and a gas carrying the fuel into the combustion furnace, and a liquid fuel nozzle for injecting liquid fuel inside the primary nozzle are arranged outside the primary nozzle. An outer peripheral flow path for supplying a single or a plurality of oxygen-containing gases for combustion, and at a tip of the single or plural outer peripheral paths, the oxygen-containing gas for combustion is directed outward with respect to the burner center axis. In a solid fuel combustion burner in which a spreading guide plate is provided and a swirl generator is provided on the upstream side in the outer peripheral flow path, the swirl generator is weakened or no swirl during operation to suppress the spread of oxygen-containing gas for combustion. A method for burning a solid fuel combustion burner, further comprising suppressing the spread of oxygen-containing gas for combustion.

(4) A primary nozzle for supplying a powdered solid fuel and a gas for transporting the fuel to a combustion furnace, and a liquid fuel nozzle for injecting a liquid fuel inside the primary nozzle are arranged outside the primary nozzle. An outer peripheral flow path for supplying a single or a plurality of oxygen-containing gases for combustion, and at a tip of the single or plural outer peripheral paths, the oxygen-containing gas for combustion is directed outward with respect to the burner center axis. A solid fuel combustion burner, comprising a guide plate for spreading, and adjusting means for suppressing the spread of the oxygen-containing gas for combustion to the outside.

The adjusting means for suppressing the spread of the oxygen-containing gas for combustion includes a cylindrical or cone-shaped sleeve disposed near the guide plate in the outer peripheral flow path, and a movement adjusting means for moving and adjusting the sleeve in the burner axial direction. A cylindrical or cone-shaped sleeve disposed in the outer peripheral flow path, and a variable resistor capable of adjusting the size of the divided flow path on the guide plate side of the outer peripheral flow path divided by the sleeve It is possible to adopt a configuration in which a body is disposed, a guide plate itself capable of adjusting movement for spreading oxygen-containing gas for combustion outward, and a movement adjusting member for adjusting movement of the guide plate in the burner axis direction.

Further, the above solid fuel combustion burner of the present invention includes a swirl generator upstream of the outer peripheral flow path, and cooperates with adjusting means for suppressing the spread of the oxygen-containing gas for combustion. Means for adjusting the degree of rotation of the oxygen-containing gas may be provided.

According to the present invention, the spread of tertiary air is maximized by the guide plate at the time of coal combustion, so that an excessive fuel region required for low NOx combustion is formed at the center of the flame. It is possible to suppress the spread of air and to promote the supply of air to the center of the flame, to suppress the generation of gas-phase deposited carbon, and to obtain optimal combustion for both coal combustion and oil combustion.

[0013]

Embodiments of the present invention will be described with reference to the drawings. The example shown in FIG. 1 has a configuration in which a spread suppressing sleeve 21 is added to the flow path of the tertiary air 9 in the structure of the conventional pulverized coal combustion burner shown in FIG. The spread suppressing sleeve 21 can be moved back and forth in the burner axis direction by an adjusting shaft 22 connected to the sleeve 21. When the spread suppressing sleeve 21 is moved toward the combustion furnace 4, the air 23 flowing along the guide plate 11 partitioned by the suppressing sleeve 21 is blocked by the suppressing sleeve 21 and
Supply to the inside is suppressed. Only the air 24 that travels straight on the outer peripheral side from the suppression sleeve 21 is supplied. As a result, the spread of the tertiary air 9 is suppressed. In addition, the spread of the tertiary air 9 is further suppressed by reducing the swirl strength of the tertiary air 9 by the tertiary air swirl generator 10 of FIG.
At this time, a small amount of air for cooling the guide plate 11 may be supplied by opening a gap between the spread suppressing sleeve 21 and the guide plate 11. Also in this case, since the flow rate of the air 24 traveling straight is large, the spread of the tertiary air 9 is suppressed.

When the expanding sleeve 21 is retracted toward the wind box 5 as shown in FIG. 2, the air flowing along the guide plate 11 has the same structure as the conventional burner shown in FIG. The spread of the air 9 is maintained. Adjusting shaft 22
By attaching a drive device such as an air cylinder to the motor, automatic operation becomes possible.

In the embodiment of the present invention shown in FIG. 4, a variable resistor is provided in which a spread suppressing sleeve 21 is fixedly installed in the flow path of the tertiary air 9 and is movable back and forth along the outer periphery of the sleeve 21. 25 is provided. By moving the variable resistor 25 in the direction of the combustion furnace 4, the flow rate of the air 23 flowing along the guide plate 11 in the flow path of the tertiary air 9 is increased, so that the tertiary air 9 has a spread flow. Form.
Further, by moving the variable resistor 25 in a direction away from the combustion furnace, the opening degree of the variable resistor 25 is reduced, and the flow rate of the air 23 flowing along the guide plate 11 is reduced. The flow rate of the air 24 flowing through the outer peripheral portion of the suppression sleeve 21 that is not affected or has little influence is increased, and the spread of the tertiary air 9 is suppressed.

The variable resistor 25 is moved using an opening adjusting shaft 26 connected to the variable resistor 25.
By attaching a drive device such as an air cylinder to the
Automatic operation becomes possible.

FIG. 5 shows an example in which the guide plate 11 is movable back and forth. By moving the guide plate 11 to the position of the burner tip, a flow of the tertiary air 9 equivalent to the conventional pulverized coal combustion burner of FIG. 8 is formed. Also,
As shown in FIG. 6, by moving the guide plate 11 toward the wind box 5, the tertiary air 9 once collides with the outer wall 28 of the combustion furnace 4 and forms a flow of the air 24. 9 is suppressed. The movement of the guide plate 11 can be automatically performed by using an adjustment shaft 27 connected to the guide plate 11 and attaching a driving device such as an air cylinder to the adjustment shaft 27.

FIG. 7 shows an example in which a cone shape is applied as the spread suppressing sleeve 21. In this example, the height of the guide plate 11 (the height H in the direction perpendicular to the gas flow direction) is high, and if the cylindrical expansion suppressing sleeve 21 as shown in FIG. 1 is applied, the flow area of the air 24 cannot be secured. This is an effective method in cases. The spread of the tertiary air 9 is suppressed by moving the spread suppressing sleeve 21 'to the combustion furnace 4 side similarly to the cylindrical sleeve 21 shown in FIG. 1, and the spread suppressing sleeve 21' is pulled out to the wind box 5 side ( The position of the dashed line) can make the tertiary air 9 wider. By attaching a driving device such as an air cylinder to the adjusting shaft 22 ', automatic operation becomes possible.

Further, in a burner having an air spreading mechanism by the guide plate 11 for the secondary air 6, the spread of the secondary air 6 is also reduced by applying the same method as the above-described method of suppressing the spread of the tertiary air 9. Is suppressed. FIG. 3 shows an example in which a spread suppressing sleeve 14 is also provided on the upstream side of the guide plate 13 arranged at the outlet of the secondary air 6. The sleeve 14 is used when both the secondary air 6 and the tertiary air 9 are in oil combustion.
Is inserted into the combustion furnace side by the adjusting shaft 15 to suppress the spread of air, and when coal is fired, the sleeve 14 is attached to the wind box 5.
By pulling out to the side to ensure the spread of air, proper combustion can be maintained.

[0020]

According to the present invention, during coal combustion, the spread of tertiary air is maximized by the guide plate to form a region of excess fuel necessary for low NOx combustion at the center of the flame, and the spread of tertiary air during oil combustion. , The supply of air to the center of the flame is promoted, and the generation of gas-phase deposited carbon can be suppressed, so that optimal combustion can be obtained for both coal combustion and oil combustion.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a pulverized coal burner according to an embodiment of the present invention when tertiary air spread is suppressed.

FIG. 2 is a side sectional view of the pulverized coal burner of FIG. 1 when tertiary air spread is maintained.

FIG. 3 is a side cross-sectional view of the pulverized coal burner according to the embodiment of the present invention when the spread of secondary air and tertiary air is suppressed.

FIG. 4 is a side cross-sectional view of a pulverized coal burner that suppresses the spread of tertiary air according to the embodiment of the present invention.

FIG. 5 is a side sectional view of the pulverized coal burner according to the embodiment of the present invention when tertiary air spread is maintained.

FIG. 6 is a side sectional view of the pulverized coal burner of FIG. 5 when tertiary air is prevented from spreading.

FIG. 7 is a side sectional view of a pulverized coal burner according to an embodiment of the present invention, in which a cone shape is used as a suppression sleeve for adjusting the spread of tertiary air.

FIG. 8 is a diagram showing an example of a structure of a burner according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixed fluid 2 Primary nozzle 3 L-type flame stabilizer 4 Combustion furnace 5 Wind box 6 Secondary air 7, 10 Swirling generator 9 Tertiary air 11, 13 Guide plate 12 Oil burner 14, 21 Suppression sleeve 15, 22 Adjustment shaft 23, 24 25 Variable resistor 26 Opening adjustment 27 Adjustment axis

Claims (8)

[Claims] 1. A primary nozzle for supplying a powdered solid fuel and a gas carrying the fuel to a combustion furnace, a liquid fuel nozzle for injecting a liquid fuel inside the primary nozzle, and a single nozzle outside the primary nozzle. An outer peripheral flow path for supplying one or more oxygen-containing gases for combustion, and the direction of the oxygen-containing gas for combustion is expanded outward with respect to the central axis of the burner at the end of the single or plural outer peripheral paths. In a solid fuel combustion burner with a guide plate, the oxygen-containing gas for combustion in the outer peripheral channel is expanded outward during solid fuel combustion, and the oxygen-containing gas for combustion in the outer peripheral channel is expanded outward during liquid fuel combustion. A method for burning a solid fuel combustion burner, characterized by suppressing. 2. After adjusting the spread of oxygen-containing gas for combustion to an optimum state for both fuels by manual operation or automatic operation based on the result of confirming both the liquid fuel combustion state and the solid fuel combustion state. The method for burning a solid fuel combustion burner according to claim 1, wherein this state is fixed. 3. A primary nozzle for supplying a powdered solid fuel and a gas carrying the fuel to a combustion furnace, and a liquid fuel nozzle for injecting a liquid fuel inside the primary nozzle, wherein a single nozzle is provided outside the primary nozzle. An outer peripheral flow path for supplying one or more oxygen-containing gases for combustion, and the direction of the oxygen-containing gas for combustion is expanded outward with respect to the central axis of the burner at the end of the single or plural outer peripheral paths. In a solid fuel combustion burner that has a guide plate and a swirl generator upstream of the outer flow path, the swirl of the swirl generator is reduced or no swirl during operation to suppress the spread of oxygen-containing gas for combustion. A method for burning a solid fuel combustion burner, further comprising suppressing the spread of oxygen-containing gas for combustion. 4. A primary nozzle for supplying a powdered solid fuel and a gas carrying the fuel to a combustion furnace, a liquid fuel nozzle for injecting a liquid fuel inside the primary nozzle, and a single fuel nozzle outside the primary nozzle. An outer peripheral flow path for supplying one or more oxygen-containing gases for combustion, and the direction of the oxygen-containing gas for combustion is expanded outward with respect to the central axis of the burner at the end of the single or plural outer peripheral paths. A solid fuel combustion burner comprising: a guide plate; and adjusting means for suppressing the outward spread of the oxygen-containing gas for combustion. 5. The adjusting means for suppressing the spread of the oxygen-containing gas for combustion includes a cylindrical or cone-shaped sleeve disposed near a guide plate in the outer peripheral flow path, and a movement for moving and adjusting the sleeve in the burner axial direction. The solid fuel combustion burner according to claim 4, comprising an adjusting member. 6. An adjusting means for suppressing the spread of the oxygen-containing gas for combustion includes a cylindrical or cone-shaped sleeve disposed in the outer peripheral passage, and a guide plate side of the outer peripheral passage divided by the sleeve. 5. The solid fuel combustion burner according to claim 4, wherein a variable resistor capable of adjusting the size of the divided flow path is arranged. 7. The adjusting means for suppressing the spread of the oxygen-containing gas for combustion includes a guide plate capable of adjusting the movement of the oxygen-containing gas for combustion outward and a movement adjusting member for adjusting the movement of the guide plate in the burner axial direction. The solid fuel combustion burner according to claim 4, comprising a member. 8. A swirl generator is provided on the upstream side of the outer peripheral flow path, and the degree of swirling of the oxygen-containing gas for combustion by the swirl generator is adjusted in conjunction with adjusting means for suppressing the spread of the oxygen-containing gas for combustion. The solid fuel combustion burner according to claim 4, further comprising means.