JP2001012703A - Burner, and combustor equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner and a combustor equipped with the burner capable of preventing ash from being deposited on a fire furnace wall located in the vicinity of the burner without use of an expensive apparatus and without causing combustion to become unstable, and further preventing the fire furnace wall from being corroded by suppressing production of CO onto the fire furnace wall located in the vicinity of the burner. SOLUTION: A burner includes a primary flow passage 1 for inserting a mixed fluid of a fine powdered coal fuel or a liquid fuel into a fire furnace, air flow passages 2 to 4 provided on an outer periphery of the primary flow passage 1 for supplying single or a plurality of combustion airs, an outermost periphery air flow passage 5 for flowing provided on the outer periphery of the air flow passage 4 for flowing air toward a wall surface constructing the fire furnace. Part of the combustion air from the outermost flow passage 5 is flowed along a fire furnace wall 10, whereby ash is prevented from being deposited onto the fire furnace wall located in the vicinity with CO being suppressed, and hence corrosion is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner for a solid fuel or a liquid fuel and a combustion device such as a boiler provided with the burner.

[0002]

2. Description of the Related Art Since the oil crisis, pulverized coal-fired boilers have been rapidly increasing and are being built in many commercial thermal power boilers in Japan. The pulverized coal combustion systems used in these boilers include a pulverized coal burner (hereinafter, referred to as a mill) with a built-in classifier, and a pulverized coal burner that uses a carrier air to pulverize the fines of a predetermined size or less. Combustion systems that feed directly to water have been put to practical use. As burners for pulverized coal combustion, research on development and commercialization has been conducted mainly on those for the purpose of reducing NOx and those for the purpose of wide area load (minimum load reduction).

FIG. 4 shows a combustion system diagram of a pulverized coal-fired boiler. Coal is stored in a bunker 133 and sent from a coal feeder 134 to a mill 124 depending on the load on the combustion device.
The air for pulverized coal transportation is PAF (Primary Air Fan) 125
After passing through the heat exchanger 1210, the air is sent from the primary hot air duct 130 to the mill 124 via the damper 122, or the air pressurized by the PAF 125 bypasses the heat exchanger 1210 and cools the primary cold air. It is sent from the duct 131 to the mill 124 via the damper 123. The pulverized coal pulverized by the mill 124 is conveyed to a pulverized coal burner 128 of the boiler furnace 121 via a coal feeding pipe 132.

On the other hand, the combustion air is FDF (Force Draft).
Fan) 129 via heat exchanger 1210, wind box 1
27, and is conveyed to the secondary flow path and the tertiary flow path of the burner section of the boiler 121.

The exhaust gas discharged from the boiler furnace 121 is supplied to a denitration device 135, a heat exchanger 1210, and a dust collector 13.
6. It is discharged into the atmosphere via the desulfurization device 137 sequentially. Further, part of the boiler exhaust gas is supplied from the GR input duct 1212 below the furnace 121 by the GRF 1211 to the furnace 12.
It is re-entered in 1.

As a technique for reducing NOx in pulverized coal burners,
The combustion air is divided and supplied into the furnace from the outer periphery of the primary flow path, which is a flow path for a mixed fluid of pulverized coal and primary air for fuel transfer, so as to easily form a NOx reducing atmosphere in the center of the flame. There is a technique of a method of turning the combustion air to be swirled to delay mixing with the mixed fluid that is igniting and burning only with the primary air supplied into the primary flow path.In a burner of such a method, Of the plurality of combustion air flow paths provided on the outer circumference of the primary flow path, the supply amount is increased as the amount of air in the combustion air flow path on the outer circumference side increases.

[0007] Among such burners of the combustion air multi-stage injection system, there is a combustion air three-division system burner, which has been put into practical use as a pulverized coal low NOx burner (Japanese Patent No. 1750459).

In the pulverized coal combustion apparatus such as the above-mentioned coal combustion boiler, a problem is adhesion of slag formed on a furnace wall (hereinafter, also referred to as a water wall or a furnace wall) around a burner. In the vicinity of the burner, the slag tends to adhere to the furnace wall because the concentration of coal is higher than other parts of the furnace in addition to the high ambient temperature. Further, since the area around the burner becomes a gas flow circulation area, when particles are taken into this area, the probability of adhering to the furnace wall increases, and slag tends to adhere to the furnace wall near the burner.

As a conventional apparatus for removing ash (slag) in a coal-fired boiler, a soot blower (an ash removing apparatus attached to a heat transfer tube in a furnace outlet bank) or a wall blower (an ash attached to a water wall surface in a furnace) is used. Removal device) has been put to practical use, but is not installed near the burner. As a method of preventing ash adhesion on the furnace wall near the burner, there is a burner structure (Japanese Patent Laid-Open No. 8-285231) in which a part of the tertiary air flows along the furnace wall. Since it flows along, the stability of the flame cannot be achieved.

[0010]

If ash or slag adheres to the surface of the furnace heat transfer wall as well, the heat transfer efficiency in this region is reduced, causing the boiler efficiency to be reduced.

As a countermeasure against this, conventionally, a compressible fluid has been blown out from a nozzle using a soot blower or a wall blower, and the attached slag has been blown off by the pressure. However, this method has problems such as the fact that these particles are sprayed on the surface of the heat transfer tube and the surface of the heat transfer tube is worn, because the range to blow off is small and the surrounding ash is entrained during the operation of the boiler. It had been. Therefore, it could not be mounted on the furnace wall near the burner.

Further, when a compressive fluid is blown out from a nozzle to a furnace wall near a burner, there is a problem that combustion becomes unstable. In addition, the operation of soot blowers and wall blowers requires expensive power sources such as compressed air and steam, which act as factors that reduce power generation efficiency. is needed.

Further, in the burner structure in which a part of the tertiary air flow is caused to flow along the furnace wall, the tertiary air flow is divided, so that it does not fulfill the role of the tertiary air and combustion becomes unstable. .

In the conventional combustion apparatus, since the vicinity of the furnace wall near the burner is a stagnation region of the combustion gas flow, C
O is generated, and there is a problem that the furnace wall is likely to corrode.

An object of the present invention is to prevent ash deposition on the furnace wall near the burner and corrosion of the furnace wall without using expensive equipment and without making combustion unstable, and furthermore, to generate CO. And a combustion device provided with the burner.

[0016]

The above object is achieved by providing a primary flow path for charging a mixed fluid of a solid fuel and a carrier gas or a liquid fuel into a furnace and a single or a plurality of flow paths provided on the outer periphery of the primary flow path. An oxygen-containing gas flow path for combustion for supplying oxygen-containing gas for combustion, and an outermost peripheral combustion chamber in which the oxygen-containing gas for combustion provided on the outer periphery of the oxygen-containing gas flow path for combustion flows toward the furnace wall surface in the furnace. The problem is solved by a burner provided with an oxygen-containing gas flow path.

According to the present invention, a part of the combustion air flows along the furnace wall from the outermost combustion oxygen-containing gas flow path, which is the outermost flow path, to reduce ash adhesion to the furnace wall near the burner. It is intended to prevent the corrosion of the furnace wall and suppress the generation of CO.

Further, by providing a deflection plate for flowing the oxygen-containing gas for combustion along the furnace wall at the end of the oxygen-containing gas channel for the outermost peripheral combustion, the combustion air flowing from the outermost gas channel is provided. It is possible to reliably flow along the furnace wall and prevent unstable combustion near the burner.

If a flow rate adjusting mechanism for adjusting the gas flow rate is provided in the oxygen-containing gas flow path for outermost circumference combustion, the gas flow rate from the outermost circumference of the burner can be adjusted, and the slag can easily adhere to the furnace wall. When fuel is used, the gas flow rate is increased (for example, 40 m / s), and when fuel having properties that slag hardly adheres to the furnace wall is used, the gas flow rate is such that no stagnation region is formed on the furnace wall (for example, 20 m / s). It can be.

Further, a heat insulating material may be provided in a ring shape outside the outermost peripheral oxygen-containing gas flow path so as to be in contact with the furnace wall surface. By using a heat-insulating material that could not be used in a conventional boiler or other combustion device as a member that forms the oxygen-containing gas flow path for combustion of the burner, the deflection plate can be pulled out together with the heat-insulating material without damaging the furnace wall. The burner can be easily taken out, and the maintainability of the burner can be improved.

Further, when the heat insulating material and the oxygen-containing gas flow path for the outermost peripheral combustion are integrated, the maintainability of the burner can be further improved.

The present invention also includes a combustion device such as a boiler or a heating furnace provided with the burner.

[0023]

Embodiments of the present invention will be described with reference to the drawings. The embodiment shown in FIG. 1 will be described. The nozzle pipe of the burner shown in FIG. 1 is composed of a plurality of flow paths, and the liquid fuel injection nozzle 1 and a flow path for a mixed fluid of pulverized coal and pulverized coal conveying air (hereinafter, may be referred to as a pulverized coal flow path) from the center. ) 2, secondary air flow path 3, tertiary air flow path 4,
The outermost air passages 5 are arranged concentrically in this order.

A deflection plate 6 for flowing air along the furnace wall is provided at the end of the outermost air passage 5. Further, a flame holding plate 7 is arranged on the outer periphery of the outlet of the pulverized coal flow path 2, and a tertiary air swirler 9 is provided in the tertiary air flow path 4. A regulator (not shown) can control the strength of the swirling of the tertiary air flow.

The secondary air flow ejected from the secondary air passage 3 into the furnace 121 (FIG. 4) is accompanied by the tertiary air flow,
The tertiary air flow spreads around due to strong swirling. On the other hand, since the pulverized coal stream ejected from the pulverized coal passage 2 is ejected from the burner into the furnace as a substantially straight stream, the mixing with the secondary air stream and the tertiary air stream spreading outward is delayed, and While maintaining the concentration, an ignition flame holding region is formed, and a wide reduction region is formed near the burner to reduce NOx.
A deflection plate 6 is provided at the outlet of the outermost air flow path 5,
The outermost air flows along the furnace wall 10. The liquid fuel injection nozzle 1 used for the pulverized coal burner is used for igniting the pulverized coal fuel when the burner is started.

In the burner shown in FIG. 1, a small amount of the outermost peripheral air flows from the outermost peripheral air passage 5 in order to maintain a low NOx flame.
The outermost air flow rate is adjusted by the damper 11, and the ratio of the slag to the furnace wall is 0.1 or less with respect to the theoretical air amount. When using fuel with a property that does not easily adhere, the fuel is flowed at such a rate that a stagnation region cannot be formed between the burners. The damper 11 is used for adjusting the flow rate of the outermost air.

Since the outermost air flow is caused to flow along the furnace wall 10 by the deflecting plate 6 without being entrained by the tertiary air flow,
The flow rate is 20 to 40 m / s. The deflecting plate 6 is liable to burn out, but does not burn out because the outermost airflow always flows inside the deflecting plate 6. Further, since cooling is performed by always flowing air inside, there is no possibility that slag adheres to the deflection plate 6.

Since the outermost air stream flows along the furnace wall 10, the performance of the low NOx burner formed inside the furnace is not reduced and the combustion is not unstable. The flow rate of the pulverized coal flow at the burner outlet is set to 15 to 25 m / s from the viewpoint of preventing pulverized coal from accumulating in the nozzle pipe (securing the minimum flow rate) and considering the wear of the pipe (restricting the maximum flow rate). In order to suppress the rotation, a structure that does not give a turn is adopted. A heat insulating material 8 is provided in a ring shape on the outer peripheral portion of the outermost peripheral air flow path 5 connecting the furnace wall 10 and the burner, and the burner integrated with the heat insulating material 8 can be easily pulled out of the furnace and has excellent maintainability. It has a structure.

Next, a second embodiment of the present invention shown in FIG. 2 will be described. FIG. 2 shows an example applied to a liquid fuel burner. The nozzle pipe of the burner shown in FIG. 2 also has a plurality of flow paths as in the nozzle pipe of the burner shown in FIG. 1, and the liquid fuel injection nozzle 1, the primary air flow path 2, the secondary air flow path 3, the tertiary air flow The path 4 and the outermost air path 5 are arranged concentrically in this order.

A tertiary air swirler 9 is provided in the tertiary air flow path 4. The tertiary air swirler 9 is provided with a tertiary air regulator (not shown) which can be operated from the outside. Can be controlled.

A deflection plate 6 is provided at the end of the outlet of the outermost air passage 5 which is the outermost combustion gas passage so that a small amount of combustion air flows along the furnace wall 10.
In addition, a damper 11 is provided in the outermost air passage 5 to adjust the flow rate.

Even when the air flow path at the outer circumference of the fuel flow path is divided into four or more parts as in the burner shown in FIG. 2, the air flow rate at the outermost circumference is set to 0.1 or less of the theoretical air amount and the gas is reduced. Flow along the furnace wall 10.

The heat insulating material 8 at the burner portion and the air flow path 5 at the outermost periphery
3 (FIG. 3 (a) is a partially enlarged cross-sectional view of a burner portion, and FIG. 3 (b) is a view taken along line AA of FIG. 3 (a)). . The outermost air passage 5 and the heat insulating material 8 are connected by a heat insulating material connecting member 12 and are integrated. Since the heat insulating material 8 and the outermost air flow path 5 are integrated,
The burner portion shown in FIGS. 1 and 2 can be easily replaced, and the structure is excellent in maintainability.

The burner described in the above embodiment of the present invention is capable of adhering ash to the furnace wall in the vicinity of the burner without deteriorating the performance of the low NOx burner and without destabilizing the combustion. This has the effect of preventing corrosion and suppressing CO generation.

[0035]

According to the present invention, the fuel can be stably burned without using an expensive device and without deteriorating the performance of the low NOx burner, and the ash adheres to the furnace wall near the burner. It is possible to provide a burner capable of preventing corrosion of a furnace wall and suppressing generation of CO, and a combustion device including the burner.

[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 sectional view of the burner according to the embodiment of the present invention.

FIG. 3 is a view for explaining the connection between the outermost gas flow path and the heat insulating material of the combustion apparatus shown in the first and second embodiments (FIG. 3).
FIG. 3A is a partially enlarged cross-sectional view of a burner portion, and FIG.
(A) is a view taken along the line AA.

FIG. 4 is a system diagram of a pulverized coal combustion device.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 liquid fuel injection nozzle 2 pulverized coal flow path 3 secondary air flow path 4 tertiary air flow path 5 outermost air flow path 6 deflection plate 7 flame stabilizer 8 heat insulating material 9 tertiary swirler 10 furnace wall 11 damper 12 heat insulating material connection Element

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F23D 17/00 102 F23D 17/00 102 F23L 13/02 F23L 13/02 (72) Inventor Akira Baba Takaracho, Kure City, Hiroshima Prefecture No. 3-36 Babcock Hitachi Co., Ltd. Kure Research Laboratory (72) Inventor Noriyuki Oyatsu No. 3-36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Co., Ltd. Kure Research Laboratory (72) Inventor Noboru Hoyama 3-36 Takaracho, Kure City, Hiroshima Prefecture No. B-terminus F-term in Kure Research Laboratory, Hitachi, Ltd. (Reference) 3K023 PA07 PA09 PC01 QA01 QA11 QA14 QB13 QB18 QC05 3K065 TA01 TA04 TB07 TB13 TC01 TC03 TD04 TD07 TE01 TE06 TE10 TF02 TJ03 TJ06 TL06 TM03 3K091 AA01 BB02 CCB CC DD02 FB05 FB13 FB23 FB28 FB33 FB44 FB57 FB63 FB66

Claims (6)

[Claims] 1. A primary flow path for introducing a mixed fluid of a solid fuel and a carrier gas or a liquid fuel into a furnace, and a single or a plurality of oxygen-containing gases for combustion provided on an outer periphery of the primary flow path. An oxygen-containing gas flow path for combustion, and an outermost combustion oxygen-containing gas flow path for flowing the oxygen-containing gas for combustion provided on the outer periphery of the oxygen-containing gas flow path in the furnace toward the furnace wall. A burner characterized by that. 2. The burner according to claim 1, wherein a deflection plate for flowing the oxygen-containing gas for combustion along the furnace wall is provided at the end of the oxygen-containing gas channel for the outermost peripheral combustion. 3. The burner according to claim 1, wherein a flow rate adjusting mechanism for adjusting a gas flow rate is provided in the oxygen-containing gas flow path for outermost combustion. 4. An outside of the outermost combustion oxygen-containing gas flow path,
The burner according to claim 1, wherein the heat insulating material is provided in a ring shape so as to be in contact with the furnace wall. 5. The burner according to claim 4, wherein the heat insulating material is integrated with the outermost combustion oxygen-containing gas flow path. 6. A combustion device comprising the burner according to claim 1.