JPH06272817A - Pulverized coal combustion device - Google Patents

Abstract

PURPOSE:To restrict adhering of slag or prevent adhering of slag by a method wherein some component members exposed within a combustion furnace are made of heat-resistant material to which slag generated under combustion hardly adheres or covered by the heat-resistant material. CONSTITUTION:An annular projection 6 is arranged between a mixture gas supplying pipe 1 and a third combustion air flow passage 4. The projection 6 extends over a flame holding ring 3 arranged at a circumferential end of the mixture gas supplying pipe 1 into a combustion furnace 2. Cooling air is passed within the projection 6 and a part of the cooling air is injected out of a slit 3 formed near an end disc 11. A surface of the end disc 11 of the projection 6 facing in the combustion furnace is provided with a slag adhesion preventing member 12 coated with ceramics. Or a surface of the end disc 11 made of SUS is made such that a complex ceramics of zirconium system having a thickness of 100mum is coated as the slag adhesion preventing member 12. With such an arrangement as above, adhesion of slag such as coal ash and the like to the end disc is restricted.

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 apparatus for a pulverized coal burning boiler furnace or the like, and more particularly to a pulverized coal combustion apparatus having a structure suitable for preventing adhesion of slag such as coal ash produced by combustion. Regarding

[0002]

2. Description of the Related Art In a conventional pulverized coal combustion apparatus, as shown in FIG. 1, for example, as shown in FIGS. Slits 15 and 20 for ejecting an oxygen-containing gas to prevent slugging in an oxidizing atmosphere
Is provided. However, a sufficient oxidizing atmosphere is not formed due to a shortage of oxygen supply to the projecting body 17, the temperature is higher than expected, or the combustion ash is rewound so that the end disk 18 is slugged. However, conventionally, no consideration has been given to the suppression of the occurrence of slugging.

[0003]

As described above, in the prior art, the tip of the pulverized coal combustion apparatus is exposed in the furnace and exposed to high-temperature radiant heat and rewinding of combustion ash. For example, the end shown in FIG. No consideration has been given to measures against slugging caused on the disk 18 due to insufficient formation of an oxidizing atmosphere. That is, in the unlikely event that slagging occurs and the prescribed performance as a pulverized coal combustion device cannot be exerted, once the fuel supply is stopped and the furnace operation is stopped to cool the furnace, the inside of the furnace is cooled. There was a problem in terms of maintenance, such as that an operator had to come in to remove the slag, or the pulverized coal combustion device had to be removed from the furnace to remove the slag that had adhered.

An object of the present invention is to eliminate the above-mentioned problems in the prior art, in which a slag is released from an end disk or the like at the tip of a protruding body exposed in the furnace of a pulverized coal combustion apparatus. Of heat-resistant material with good properties (heat-resistant material with poor adhesion of slag) or coating with heat-resistant material with good mold release property of slag to suppress or prevent adhesion of slag generated by combustion To provide a pulverized coal combustion device.

[0005]

In order to achieve the above-mentioned object of the present invention, a part or all of the constituent members exposed in the furnace of a pulverized coal combustion apparatus are treated as coal ash or the like produced by combustion. It is composed of a heat-resistant material having poor slag adhesion, that is, good slag releasability, or coated with a heat-resistant material having good releasability. As a material having good mold releasability of the slag, there is heat resistance, poor adhesion to the generated slag, that is, a material having poor wettability, may be used, but the material is not particularly limited, Zirconia-based composite ceramics, in which at least one lubricant selected from boron nitride, molybdenum disulfide, calcium fluoride, beryllium fluoride, etc. is added to a heat-resistant material containing zirconia as a main component, are preferably used. To be In this way, by using a heat-resistant material with good mold releasability with slag for the member exposed in the furnace of the pulverized coal combustion device and exposed to high temperature, or by coating with a heat-resistant material with good mold releasability, The desired combustion performance can be stably continued without the slag adhering to the charcoal combustion device, and it is not necessary to stop the operation of the furnace and perform the slag removal work. The present invention, in a pulverized coal combustion apparatus that performs combustion by supplying a mixture of pulverized coal and air and combustion air into a furnace, a part or all of the constituent members exposed in the furnace of the combustion apparatus The pulverized coal combustion apparatus is composed of a heat-resistant material having poor adhesion of slag generated by combustion, that is, a heat-resistant material having good mold release property of slag, or coated with a heat-resistant material having good mold release property of slag. Specifically, a gas mixture supply pipe that supplies a mixture of pulverized coal and air into the furnace, and a combustion that is outside the mixture gas supply pipe in the radial direction and that supplies a gas such as combustion air into the furnace. In the pulverized coal combustion apparatus, which comprises a projecting gas supply flow path, a projecting body that separates the mixed gas flow and the combustion gas flow between the mixed gas supply pipe and the combustion gas supply flow path, the projecting body tip is provided. This is a pulverized coal combustion apparatus in which the part is made of a heat-resistant material having a good slag releasability or the surface of the tip of the protrusion is covered with a heat-resistant slag adhesion preventing material. As the heat-resistant slag adhesion preventing material, it is desirable to use a refractory material having an adhesion force with the slag smaller than its own weight under high temperature conditions of 600 to 1000 ° C. Further, the thickness of the coated slag adhesion preventing material is 20 to 300 μ in consideration of the difference in thermal expansion.
It is preferably in the range of m.

[0006]

[Function] The protruding body 6 of the pulverized coal combustion device exposed in the furnace
The reason why coal ash (slag) adheres to the tip of (Figs. 2 and 3) is that (1) the surface temperature of the end disk 11 of the projecting body 6 depends on the softening temperature of the slag due to the radiant heat of the flame in the furnace. When the temperature becomes equal to or higher than the melting point, (2) the adhesive force due to the wettability between the surface of the end disc 11 of the projecting body 6 and the slag is caused by the weight of the attached slag or the combustion oxygen flowing around the end disc 11. Two conditions are conceivable when the flow force of the contained gas (air or the like) is stronger. Therefore, by making the slag adhesion force on the surface of the end disk 11 of the projecting body 6 smaller than the weight of the slag that adheres, the amount of air for cooling the end disk 11 of the projecting body 6 is reduced. Even if the surface temperature of the end disk 11 of the protrusion 6 rises above the softening point of the slag, the slag adhesion force of the end disk 11 is smaller than the dead weight of the slag to be adhered, so the slag adheres to the end disk 11. It will not be deposited.

[0007]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a schematic diagram showing an example of the overall configuration of the pulverized coal combustion apparatus of the present invention.
FIG. 4 is an enlarged view showing details of a protruding body portion of the combustion device exposed in the furnace. The pulverized coal combustion apparatus shown in FIG. 1 uses pulverized coal as a powdered fuel and air as an oxygen-containing gas for combustion. The air-fuel mixture supply pipe 1 has one end facing the inside of the furnace 2 through a furnace opening 8 formed in a furnace wall 7 of the furnace 2, and the other end connected to a coal crusher (not shown). ing. The mixture of pulverized coal and primary air is the mixture supply pipe 1
Flowing in. Then, the air-fuel mixture of pulverized coal and primary air is ignited, and a flame is formed in the furnace 2. Mixture supply pipe 1
An annular projecting body 6 is disposed between and the tertiary air flow path 4, which is an oxygen-containing gas for combustion. The projecting body 6 extends into the furnace 2 beyond the flame holding ring 3 in order to shield the flame holding ring 3 provided at the peripheral end portion of the mixture supply pipe 1 from radiant heat from the inside of the furnace 2. As shown in FIG. 2, for example, as shown in FIG. 2, cooling air is allowed to flow inside the protrusion 6 so that the protrusion 6 is not exposed to a high temperature by the radiant heat from the furnace 2 to cause slugging. As shown in FIG. 3, it is ejected from a slit 13 provided near the end disk 11. Then, as shown in FIG. 3, a ceramic coated slag adhesion preventing material 12 is provided on the surface of the end disk 11 of the projecting body 6 facing the inside of the furnace. As shown in FIG. 3, 100 μ of zirconia-based composite ceramics was used as the slag adhesion preventing material 12 on the surface of the end disk 11 made of SUS (stainless steel) facing the inside of the furnace of the protrusion 6.
It is coated to a thickness of m. In this embodiment, as the coating material, a composite ceramic of zirconia and boron nitride, which has excellent mold releasability from slag under high temperature conditions of 600 to 1000 ° C., is used. As a result of conducting a combustion test using the pulverized coal combustion device having the end disk 11 coated with this zirconia-based composite ceramic, the adhesion force with the slag becomes smaller than the self-weight of the slag, and the phenomenon that the slag adheres is confirmed. I couldn't do it. Further, in order to reduce the adhesive force between the coating surface of the slag adhesion preventing material 12 and the slag, it is preferable to make the coating surface as smooth as possible, which is affected by the smoothness of the base material forming the end disk 11. . The coating thickness of the slag adhesion preventing material 12 is preferably at least 20 μm or more. On the other hand, considering the cooling effect and the difference in thermal expansion from the base material, the coating thickness is preferably thin, and the maximum thickness is preferably about 300 μm. In this embodiment, the base material is coated with the slag adhesion preventing material, but it can be coated by plating or thermal spraying.

[0008]

EFFECTS OF THE INVENTION According to the present invention, the slag adhesion force on the surface of the slag adhesion preventing material coated on the exposed portion of the pulverized coal combustion apparatus in the furnace, for example, the end disk of the projecting body is more than the slag's own weight. Since it also becomes small, even under high-temperature pulverized coal combustion conditions of 600 to 1000 ° C., adhesion of slag such as coal ash, which is a combustion product, to the end disc is suppressed,
It is possible to realize a pulverized coal combustion device capable of stably continuing pulverized coal combustion while maintaining a desired high combustion performance.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a pulverized coal combustion apparatus exemplified in an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a structure of a projecting body into a furnace of the pulverized coal combustion apparatus shown in FIG.

FIG. 3 is an enlarged view of a main part of the protrusion shown in FIG.

FIG. 4 is a schematic diagram showing a structure of a projecting body of a conventional pulverized coal combustion apparatus.

5 is an enlarged view of a main part of the protrusion shown in FIG.

FIG. 6 is a schematic view showing another example of a conventional protruding body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Air-fuel mixture supply pipe 2 ... Furnace 3 ... Flame holding ring 4 ... Tertiary air flow path 5 ... Secondary air flow path 6 ... Projection body 7 ... Furnace wall 8 ... Furnace opening 9 ... Outer peripheral wall 10 ... Inner peripheral wall 11 ... edge disc 12 ... slag adhesion preventing material 13 ... slit (circumferential direction) 14 ... guide plate 15 ... slit (radial direction) 16 ... guide plate 17 ... projecting body 18 ... end disc 19 ... guide plate 20 ... slit ( Circumferential direction) 21 ... Air flow direction

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Adult Nakashita Adult 6-9 Takaracho, Kure-shi, Hiroshima Babcock Hitachi Kure Factory (72) Inventor Koji Kuramasu 6-9 Takaracho, Kure-shi, Hiroshima Babcock Hitachi Stock Company Kure Factory

Claims (5)

[Claims] 1. A pulverized coal combustion apparatus for supplying a mixture of pulverized coal and air and combustion air into a furnace for combustion,
A part or all of the constituent members exposed in the furnace of the combustion apparatus are composed of a heat-resistant material having poor adhesion of slag generated by combustion, or covered with a heat-resistant material having poor adhesion of slag. A pulverized coal combustion device characterized by the following. 2. An air-fuel mixture supply pipe for supplying an air-fuel mixture of pulverized coal and air into the furnace, and a combustion which is outside the air-fuel mixture pipe in the radial direction and supplies a gas such as combustion air into the furnace. In the pulverized coal combustion apparatus, which comprises a projecting gas supply flow path, a projecting body that separates the mixed gas flow and the combustion gas flow between the mixed gas supply pipe and the combustion gas supply flow path, the projecting body tip is provided. A pulverized coal combustion apparatus, characterized in that the part is made of a heat-resistant material having poor slag adhesion, or the surface of the tip of the protrusion is coated with a heat-resistant slag adhesion preventing material. 3. The refractory material according to claim 2, wherein the heat resistant slag adhesion preventive material is a refractory material having an adhesion force with the slag smaller than its own weight under high temperature conditions of 600 to 1000 ° C. Pulverized coal combustion equipment. 4. The slag adhesion preventing material according to claim 2 or 3, wherein the slag adhesion preventing material is a heat-resistant material containing zirconia as a main component.
At least one selected from boron nitride, molybdenum disulfide, calcium fluoride, and barium fluoride
A pulverized coal combustion apparatus comprising a zirconia-based composite material to which various kinds of lubricants are added. 5. The thickness of the coated slag adhesion preventing material according to claim 2, which is 20 to 30.
A pulverized coal combustion device characterized by having a range of 0 μm.