JPS58224208A - Uniform dispersion type pulverized coal firing equipment - Google Patents

Abstract

PURPOSE:To increase a combustion efficiency through improvement of dispersion of pulverized coal, by a method wherein a venturi is disposed in a tubular body forming a burner tube, and a vane, of which the angle is adjustable, is mounted on the downstream side of a part where the venturi is mounted. CONSTITUTION:A venturi 2 is located in a tubular body 1 forming a burner tube. A bevel gear 4 is mounted to the end part of a vane rotating shaft 3a of a pulverized coal redispersing vane 3 situated in the vicinity of the outlet of the venturi, and a device is constituted such that the attaching angle of the vane 3 is changeable through control of a lever 5. This permits jetting of pulverized coal as the pulverized coal is normally uniformalized irrespective of the jet speed of the pulverized coal, resulting in ability to normally perform a steady burning of the pulverized coal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for burning coal pulverized into fine particles, such as pulverized coal.

With recent changes in the fuel situation, the value of coal as a fuel has been reconsidered, and a considerable number of large boilers for business use, including large boilers for thermal power plants, are now using co-firing with heavy oil or only burning coal. In this case, from the viewpoint of improving the efficiency and controllability of coal combustion, a method is adopted in which the coal is pulverized to a predetermined particle size and then air-flow conveyed to the burner section. There are various particle sizes of crushed coal, but
Usually, pulverized coal with a 200 mesh passing rate or about 70 to 80% is often used (hereinafter, pulverized coal will be explained).

Since the pulverized coal supplied into the furnace is rapidly heated by the heat inside the furnace and combusted in a short time, controllability is significantly improved compared to stoker firing, etc.

Pulverized coal is normally blown out from a burner and combusted with air in an amount of 20 to 50% of the theoretical air amount, and is combusted by secondary air supplied from around the burner. In this case, the flow path is changed approximately 90 times from the pneumatic transport pipe to the burner, but as a result of this change in flow path, the pulverized coal transported by air flow is classified by inertia, and is unevenly sprayed from the burner. There is a risk that combustion may become unstable or difficult to control.

For this reason, the inventors first disposed swirling vanes in the cylindrical body constituting the burner cylinder to apply swirling force to the airflow, thereby reducing the effect of classifying the pulverized coal by changing the flow path. In addition, in this case, the pulverized coal in the airflow tends to be centrifuged toward the wall surface of the cylindrical body due to the swirling force of the airflow, so a venturi is further placed downstream of the swirling vane to reduce the area through which the airflow passes. We offer products designed to ensure uniform distribution of particles. It has been confirmed that this Venturi arrangement has a certain effect on the uniform diffusion of particles, but it is still not sufficient, and overall the pulverized coal is concentrated in the center of the flow path. It's creating a trend.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a pulverized coal combustion device in which pulverized coal is better dispersed and combustion efficiency is further improved.

In short, this invention arranges a venturi inside a cylindrical body constituting a burner cylinder, and furthermore, attaches an angle-adjustable vane to the downstream side of the venturi installation part. and, if necessary, the vane is made of highly wear-resistant ceramic.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a cylindrical body forming a burner cylinder, and 2 is a venturi formed within the cylindrical body. Reference numeral 3 denotes a pulverized coal re-diffusion vane placed near the outlet of the venturi, and a bevel gear 4 is attached to the end of the vane rotating shaft 3a, so that the angle at which the vane 3 is attached can be changed by operating a lever 5. It is. In this case, the plurality of vanes operate simultaneously by a link mechanism (not shown). Although the illustrated vanes are arranged inside the venturi, they may of course be arranged inside the cylindrical body on the downstream side of the venturi. Further, since the vane 3 itself is subject to severe wear due to the intense rubbing of the pulverized coal, it is preferable that the vane 3 be formed of highly wear-resistant ceramic. Next, reference numeral 1o denotes a guide cylinder disposed approximately on the same axis as the cylindrical body 1, and the vane 3
will be supported at one end by this guide tube. 8 is an elbow connected to the cylindrical body l; 9 is a support tube disposed inside the elbow 8; of these, the support tube 9 is connected to the guide tube 1;
I support o. Reference numeral 11 denotes a heavy oil burner disposed within the guide cylinder 10, which is mainly used for igniting pulverized coal.

Reference numeral 12 denotes a pulverized coal particle mixing vane that also functions as a support plate for supporting the support cylinder 9, and provides a swirling force to the pulverized coal-containing gas flowing from the lower part of the elbow. Reference numeral 13 indicates another pulverized coal mixing vane provided at the elbow portion, and numeral 14 indicates a pulverized coal supply pipe connected to this elbow 8.

This is a passageway for supplying air, and the air is injected from the injection port 15a to seal the burner flame from secondary air. Reference numeral 16 denotes a pipe line for supplying inert gas G to this inert gas passage. Next, 17 is a secondary air passage, which is formed around the inert gas passage.

Reference numeral 18 denotes a flow rate adjusting plate formed at the entrance of the secondary air passage, and its opening degree is adjusted by a lever 19 and a link 20 connected thereto to adjust the secondary air flow rate. Reference numeral 21 denotes an air swirling vane arranged at the outlet of the secondary air passage, and lever 23. Vane rotation shaft 2 via bevel gear 24
2 and adjust the angle of the swirling vane 21 to adjust the swirling force of the air. In this case, the angles of each of the rotating vanes are simultaneously changed by operating the lever 23 using a link mechanism (not shown). 25 is a tertiary air passage formed on the outer periphery of the secondary air passage 17, 26 is a flow rate adjustment plate provided at the entrance of the tertiary air passage, 27 is a lever for rotating the adjustment plate, and 28 is a tertiary air passage. A vane for swirling tertiary air placed at the outlet, -29. Bevel gear 30. The angle is adjusted using the vane rotating shaft to adjust the turning force of the tertiary air.

In the above apparatus, the pulverized coal-containing gas that has ascended through the pulverized coal supply pipe 14 is transferred to the elbow 8. The pulverized coal flows into the elbow after being given a swirling force by the pulverized coal mixing vane 13 at a population of
The flow path is changed by about 90°. In the case of changing the flow path at the mouth, the pulverized coal tends to be classified to the outside of the flow due to inertia, but since a swirling flow is formed by the vanes 13, the classification tends to be suppressed. A swirling force is applied to the airflow after changing the flow path by another vane 12.

As a result, the pulverized coal in the airflow tends to be centrifuged toward the inner circumferential wall of the cylindrical body 1. Figure 2 shows the state of dispersion of this pulverized coal. The concentration of pulverized coal C increases as it approaches the inner wall surface of the cylindrical body 1, and its distribution is However, it is uniformly dispersed in the circumferential direction 4 of the inner wall of the cylindrical body, and no high concentration area or low concentration area is formed in a part of the inner wall surface. In this state, airflow flows into the venturi. In this venturi 2, the area through which the airflow passes is reduced, and the pulverized coal is evenly distributed even on a plane perpendicular to the direction of airflow movement. However, at the outlet of the venturi, the airflow itself diffuses as shown in A, but the pulverized coal, especially those with large particle diameters, tends to travel straight due to inertia, as shown in Ap. It will be mostly distributed on the 10 side. For this reason, the vanes 3 apply swirling force to the airflow again to finally disperse the pulverized coal uniformly and inject it into the furnace for combustion. By adjusting the angle of the vane 3 using the lever 5 in accordance with the airflow velocity, the pulverized coal can be constantly dispersed.

By carrying out this invention, pulverized coal is always injected while being uniformly dispersed regardless of the injection speed of the pulverized coal, so that stable pulverized coal combustion can be performed at all times.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a pulverized coal combustion apparatus showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A--A in FIG. 1. l...Cylindrical body 2...Venturi 3...Pulverized coal re-diffusion vane 3a...
・Vane rotation shaft 4...Bevel gear 5...Shinoku-8...Elbow 10...Guide cylinder 13...Pulverized coal Diffusion vane

Claims (1)

[Claims] 1. In a device in which the flow direction of pulverized coal is changed by an elbow and the pulverized coal is injected from a cylindrical body for combustion, a vane for dispersing the pulverized coal is formed in the elbow, and a vane for dispersing the pulverized coal is formed in the elbow. Uniform diffusion type pulverized coal combustion characterized by a venturi being formed inside the cylindrical body on the downstream side of the forming part, and a vane for airflow re-diffusion whose attachment angle is adjustable on the downstream side of the venturi forming part. Device. 2. The angle adjustment of the airflow re-diffusion vane is made up of a vane rotating shaft attached to the vane and a lever connected to the vane rotating shaft via a bevel gear. A uniform diffusion type pulverized coal combustion device according to scope 1. 3. A uniform diffusion type pulverized coal combustion device according to claim 1 or 2, wherein the airflow re-diffusion vane is made of ceramics.