JP2738705B2 - Pulverized coal burner and pulverized coal combustion device using it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pulverized coal combustion apparatus, and particularly in the case of pulverized coal combustion of high fuel ratio coal (low volatile coal), it has extremely good flame holding properties. The present invention relates to a burner device having a large flame stable combustion range and a pulverized coal combustion device using the burner device.

[Conventional technology]

The conventional pulverized coal combustion apparatus is equipped with a cyclone type pulverized coal concentration riser 3 in the middle of the pulverized coal transport pipe 2 as shown in FIG. 4, for example, but the exhaust pipe 5 is directly connected to the pulverized coal burner 13. And no consideration has been given to recovering fine coal particles contained in the airflow in the exhaust pipe 5. [Thermal and Nuclear Power, Vol. 38, No. 367 (April 1987), page 61]. Further, since the amount of the fine coal particles in the exhaust pipe 5 is extremely small with respect to the amount of air in the exhaust pipe 5, it is impossible to form a pulverized coal flame by itself, and therefore, The use of pulverized coal burners to improve the flame holding function was never considered.

[Problems to be solved by the invention]

In a pulverized coal burner, particularly in a pulverized coal burner burning high-fuel-ratio coal, the main factors affecting the flame holding performance of the burner are: (1) The ratio of pulverized coal to carrier air, that is, the concentration of pulverized coal in the carrier air. , (2) the temperature of the carrier air, (3) the particle size of the pulverized coal, and the like.

Regarding the above factor (1), the pulverized coal concentration [coal (k
g) / air (kg)], the better the flame holding properties of the burner.
Regarding (2), the higher the temperature of the conveying air, the better the flame holding properties of the burner. Regarding (3), the more the fine particles having a particle size of pulverized coal of about 30 μm or less, the better the flame holding performance of the burner. improves.

However, due to the problem of the control function of the coal pulverizing mill actually operated in connection with the pulverized coal burner, the above (1)
Factors (2) naturally have their upper limits, and it is more convenient to operate the pulverized coal burner if the pulverized coal concentration is not too high and the temperature of the conveying air is not too high. The factor (3) is governed by the pulverizing capacity of the coal pulverizing mill and the collecting performance of the fine particles of the pulverized coal concentration increasing device 3 installed in the middle of the pulverized coal transport pipe 2. Thus, there was a problem that the particle size of the pulverized coal could not be adjusted to a value within a desirable range for the flame holding of the burner.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to maintain the pulverized coal particle size optimal for improving the flame holding performance of the pulverized coal burner to expand the flame stable combustion range of high fuel ratio coal. An object of the present invention is to provide a pulverized coal burner to be measured and a pulverized coal combustion device using the burner.

[Means for solving the problem]

An object of the present invention is to provide a pulverized coal combustion burner device which collects fine coal particles (having a particle size of about 30 μm or less) exhausted from a pulverized coal concentration riser provided in a pulverized coal transportation pipeline. For example, a collector of a bag filter type is disposed for collection, and the fine coal particles collected by the collector are injected into a burner cylinder of a pulverized coal burner provided with a guide plate for the fine coal particles. Is achieved by burning.

The pulverized coal burner according to the present invention includes a tertiary air register and a guide sleeve for supplying combustion air into a burner throat.
A burner tube for supplying a mixed air flow of pulverized coal and air pneumatically transported from a secondary air register, a secondary air vane, and a pulverized coal transport line into a combustion furnace, and a tip end inside the furnace of the burner tube; Pulverized coal burner provided with a flame stabilizer, provided at one end of the furnace outside the burner cylinder, an injector for injecting the fine coal particles collected in the pulverized coal supply system into the interior of the burner cylinder. Pulverized coal burner.

And in the pulverized coal burner of the present invention, it is preferable to provide a guide plate of fine coal particles which forms a predetermined space between the burner cylinder and the inner surface of the burner cylinder. Further, in the pulverized coal burner of the present invention, it is desirable to provide a bellmouth type guide plate at the furnace outer end of the guide plate of fine coal particles installed inside the burner cylinder.

The pulverized coal combustion device of the present invention, a coal pulverizing mill for supplying pulverized coal, and pulverized coal generated by the mill, via a pulverized coal concentration riser installed in a pulverized coal transport pipeline,
A pulverized coal combustion device for supplying and burning a pulverized coal burner according to the present invention, wherein a pulverized coal burner for collecting fine coal particles discharged from an exhaust pipe of the pulverized coal concentration raiser, for example, a bag filter type collector is provided. And a conduit for connecting the fine coal particles collected by the collector to a fine coal particle injector provided in a burner cylinder of the pulverized coal burner.

Further, in the pulverized coal combustion device of the present invention, even if a conduit for injecting the fine coal particles collected by the collector into the pulverized coal transport pipe for supplying pulverized coal to the pulverized coal burner is provided,
The object of the present invention is achieved.

[Action] As a pulverized coal concentration increaser, a mechanical pulverized coal concentration increaser such as a cyclone is usually used.
Mixing of pulverized coal and air that reaches the burner cylinder of the pulverized coal burner via the pulverized coal transport pipe because fine coal particles of about 30μm or less, which are desirable for flame holding of the burner, are discharged from the exhaust pipe of the pulverized coal concentration riser. The proportion of fine coal particles desired for flame holding contained in the air stream will be extremely reduced. But,
By using the pulverized coal combustion means according to the present invention, the fine coal particles once lost are collected and collected, and injected into the burner cylinder of the pulverized coal burner or into the pulverized coal transportation pipeline leading to the burner. Since the burner can maintain the desired fine particle size of coal for flame holding, the flame stable combustion range of the burner can be expanded, and stable pulverized coal combustion can be continued even with high fuel ratio coal.

In addition, a guide plate is installed at the injection part of the fine coal particles in the burner cylinder to prevent the fine coal particles from being unnecessarily diffused into the mixed air flow of pulverized coal and air, and the flame holding at the tip of the burner nozzle. It functions so that fine coal particles are efficiently guided to the part.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view showing a cross-sectional structure of a pulverized coal burner of the present invention, in which a burner body includes a burner throat 11, a guide sleeve 12, a secondary air register 14, and a tertiary air register.
15, a secondary air vane 16 and a burner cylinder 10. A burner 17 is provided at the front end of the burner tube 10 inside the furnace, and the secondary air entrained by the burner 17 forms a small vortex inside the flame holder. The pulverized coal ignited near here. Secondary air register 14, Tertiary air register 15 and Secondary air vane
16 functions as a swirler and is adjusted to form a flame structure according to the purpose, such as low NOx combustion.

The injector 9 mounted on the outside of the burner tube 10 is for feeding fine coal particles into the burner tube 10 therethrough. Inside the burner tube 10, fine coal particles are injected into the burner tube 10. Along the inner surface of 10, the flame stabilizer at the tip inside the furnace
A guide plate 18 for leading to the vicinity of 17 is mounted. In the space formed between the inner surface of the burner cylinder 10 and the outer surface of the guide plate 18, the fine coal particles are conveyed at an appropriate speed to the vicinity of the flame stabilizer 17 at the front end of the furnace. A part of the air flowing from the pulverized coal transport pipe 4 is taken in. The bellmouth type guide plate 19 facilitates the intake of air and distributes the appropriate amount of air.
Its shape is set.

FIG. 2 shows the fine coal particles in the exhaust pipe 5 from the cyclone type pulverized coal concentration riser 3 installed in the middle of the pulverized coal transport pipe 2 connected to the coal pulverizing mill 1, and the bag filter type. While being collected by the fine coal particle collector 6, only air is discharged from the exhaust pipe 8 to the atmosphere. On the other hand, a configuration example is shown in which the fine coal particles are introduced into the burner cylinder 10 from the injection portion 9 of the burner cylinder 10 from the fine coal particle transport pipe 7 by an air flow or a mechanical conveying means.

The fine coal particles conveyed toward the furnace inner end portion in the annular space formed by the inner surface of the burner cylinder 10 and the outer surface of the guide plate 18 reach the vicinity of the flame stabilizer 17 and form secondary air. The entrainment causes the flow of the minute air vortex formed behind the flame stabilizer 17 to effectively function as a fuel source essential for maintaining the burner ignition.

〔The invention's effect〕

As described above in detail, the pulverized coal burner of the present invention and the pulverized coal combustion apparatus using the same have the following effects.

(1) Fine coal particles (approximately 30 μm or less) that greatly contribute to the flame stability of the burner can be supplied to the flame stabilizer of the burner without reducing the concentration of the fine coal particles, thereby expanding the flame combustion range. And stable pulverized coal combustion can be continued.

(2) Since fine coal particles effective for flame holding can be recovered and adjusted to an appropriate fine coal particle concentration and supplied to a burner, as shown in FIG. It is possible to expand the flame stable combustion range of the fuel-to-fuel ratio.

(3) Fuel oil for combustion under low burner load conditions such as boiler start-up (low secondary and tertiary air temperatures, low pulverized coal / transport air weight ratio, extremely unstable flame) Can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a sectional structure of a pulverized coal burner exemplified in the embodiment of the present invention, FIG. 2 is a system diagram in a case where the pulverized coal burner of the present invention is applied to a pulverized coal combustion system, and FIG.
FIG. 4 is a graph showing a flame stable range of the pulverized coal burner of the present invention exemplified in the embodiment, and FIG. 4 is a system diagram showing a conventional pulverized coal combustion system. DESCRIPTION OF SYMBOLS 1 ... Coal pulverizing mill, 2 ... Pulverized coal transportation pipe 3 ... Pulverized coal concentration raiser 4 ... Pulverized coal transportation pipe 5, ... Exhaust pipe 6 ... Fine coal particle collector 7 ... Fine coal particles Transport pipe 8 ... Exhaust pipe, 9 ... Injector 10 ... Burner cylinder, 11 ... Burner throat 12 ... Guide sleeve, 14 ... Secondary air register 15 ... Tertiary air register, 16 ... Secondary Air vane 17 …… flame holder, 18 …… guide plate 19 …… guide plate

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeki Morita 6-9 Takara-cho, Kure-shi, Hiroshima Pref. Inside the Kure Plant of Babcock Hitachi Ltd. (56) References JP-A-57-12209 (JP, A) JP-A Sho 62-116810 (JP, A) JP-A-1-117444 (JP, A) JP-A-60-223914 (JP, A) JP-A-61-44214 (JP, A) JP-A-62-210308 (JP, A) A)

Claims (6)

(57) [Claims] 1. A burner cylinder for supplying a mixed air flow of pulverized coal and air, which is pneumatically transported by a pulverized coal transportation pipe from a coal pulverizing mill, into a burner throat, and burns outside the burner cylinder. A flow path for supplying working air into the combustion furnace,
In a pulverized coal burner provided with a flame stabilizer at the furnace inner end of the burner cylinder, in the middle of the pulverized coal transport pipeline, a mechanical pulverized coal concentration adjusting means for adjusting the pulverized coal concentration to the burner cylinder. A fine coal particle collecting means for collecting fine coal particles contained in exhaust gas in an exhaust pipe from the fine coal concentration controlling means, and a fine coal particle collecting means outside the burner cylinder. Means are provided for injecting the fine coal particles into the burner tube so that the collected fine coal particles are conveyed to the vicinity of the flame stabilizer along the inner surface of the burner tube by the mixed gas flow flowing through the burner tube. A pulverized coal burner, characterized in that: 2. A pulverized coal burner according to claim 1, wherein a guide plate of fine coal particles forming a predetermined space with the inner surface of the burner cylinder is provided inside the burner cylinder. . 3. A pulverized coal burner according to claim 1 or 2, wherein a bellmouth type guide plate is provided at a front end portion of the induction plate of the fine coal particles installed inside the burner cylinder on the outside of the furnace. Characterized pulverized coal burner. 4. The coal pulverizing mill for supplying pulverized coal, and the pulverized coal produced by the mill are passed through a pulverized coal concentration raiser installed in a pulverized coal transport line. In the pulverized coal combustion device for supplying and burning the pulverized coal burner, a collector for collecting the fine coal particles discharged from the exhaust pipe of the pulverized coal concentration riser is installed, and collected by the collector. A pulverized coal combustion apparatus, comprising a conduit for connecting the fine coal particles to a fine coal particle injector provided in a burner cylinder of the pulverized coal burner. 5. The pulverized coal combustion apparatus according to claim 4,
A pulverized coal combustion characterized by having a conduit for injecting the fine coal particles collected by a collector for collecting the fine coal particles into a pulverized coal transport pipe for supplying pulverized coal to a pulverized coal burner. apparatus. 6. The pulverized coal combustion apparatus according to claim 4,
A pulverized coal combustion apparatus, wherein the collector for collecting fine coal particles is a bag filter type collector.