JPH0227291Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pulverized coal burner that is capable of stable combustion even under low load conditions.

[Prior Art] A conventional pulverized coal burner injects pulverized coal sent in a constant amount of air from a pulverized coal mill into a furnace and burns it.

[Problem to be solved by the invention] However, when the load on the pulverized coal mill decreases, since the amount of air introduced into the mill is constant, the amount of air A/the amount of pulverized coal C increases, and the primary air ratio decreases. When the flame becomes too large, combustion spots occur, combustion becomes unstable, and eventually combustion becomes impossible.

[Means for Solving the Problems] In order to solve the above-mentioned conventional problems, the present invention introduces a mixed fuel of pulverized coal and primary air in a spiral manner, and connects it to the burner inner cylinder. In a pulverized coal burner that ejects and burns from a burner nozzle through a cylindrical flow path between the burner outer cylinder, a cylindrical separate plate is disposed between the burner inner and outer cylinders of the mixed fuel introduction part, and the mixed fuel is introduced. The separate plate of the section and the burner inner cylinder were connected to the inside of the furnace via a bleed line.

[Operation] When mixed fuel of pulverized coal with heavy specific gravity and air with light specific gravity is swirled in the mixed fuel introduction section, the pulverized coal flows toward the outer cylinder side while flowing through the cylindrical flow path between the burner inner and outer cylinders. The air ratio increases on the cylindrical side.

When the air from the inner cylinder side is discharged into the furnace through the bleed line, the A/C of the mixed fuel injected from the burner nozzle is reduced, and stable combustion is always possible even when the load on the pulverized coal mill is reduced.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

Figures 1 and 2 show an embodiment of the present invention, in which 1 is a pulverized coal burner, 2 is a burner inner cylinder, 3 is a burner outer cylinder, and 4 is a mixture of mixed fuel of pulverized coal and primary air. A fuel supply pipe, 5 is a mixed fuel introduction part, 6 is a cylindrical flow path, 7 is a burner nozzle, 8 is a burner throat, and a cylindrical separate plate 9 is arranged in the cylindrical flow path 6 of the mixed fuel introduction part 5. Set up The diameter and length of the separate plate 9 can be determined depending on the diameters of the burner inner and outer cylinders 2 and 3, the burner output, etc. For example, the diameter is expressed as the outer cylinder diameter D and the inner cylinder diameter d, and is therefore D+d/2. The appropriate length is about twice the diameter of the mixed fuel supply pipe 4.

A bypass pipe 11 is connected to the shielding plate 10 between the burner inner cylinder 2 and the separate plate 9 of the mixed fuel introduction section 5, a flow rate adjustment damper 12 is provided on the bypass pipe 11, and the bypass pipe 11 is connected to the shielding plate 10 between the burner inner cylinder 2 and the separate plate 9. A bleed air line 13 is opened near the burner nozzle 7.
has been configured. In the figure, 14 is a wind box, 15 is a combustion air supply duct, and 16 is a heavy oil burner for ignition.

With the above configuration, when the mixed fuel with high A/C is introduced from the mixed fuel introduction part 5, the mixed fuel spirals in the cylindrical flow path 6 around the burner inner cylinder 2. and flows to the burner nozzle 7 side. This swirling flow causes centrifugal force to act, and the pulverized coal with a high specific gravity concentrates on the outside (on the burner outer cylinder 3 side), causing the A/C to decrease, and on the inside (on the burner inner cylinder 2 side), the A/C decreases. significantly higher.

Since the mixed fuel is introduced in a pressurized state, the inside of the cylindrical flow path 6 becomes positive pressure, and when the opening degree of the flow rate adjustment damper 12 of the bypass pipe 11 is increased, the pressure in the furnace 17 is relatively low. Due to the difference, the mixed fuel with a significantly high A/C on the surface of the burner inner cylinder 2 flows out through the bypass pipe 11 into the furnace interior 17 near the -nano nozzle 7. At this time, separate plate 9
This prevents interference between the discharged air flow and the introduced mixed fuel, and air with a low concentration of pulverized coal is separated and discharged.

From burner nozzle 7, the amount of air is reduced and A/
Since the mixed fuel whose carbon content has decreased to a predetermined value is injected, stable combustion is possible without causing uneven combustion. The pulverized coal in the mixed fuel with extremely high A/C discharged from the bypass pipe 11 is also burnt without waste by the flame from the burner nozzle 7.

It should be noted that the pulverized coal burner of the present invention is not limited to the above-mentioned embodiment, and that one or more bypass pipes can be installed, and the number can be determined according to the burner capacity. Of course, various modifications may be made without departing from the gist of the present invention, such as opening in the burner throat portion or providing a suction device in the bleed line.

[Effect of the invention] As explained above, according to the pulverized coal burner of the present invention, by separating and discharging the mixed fuel with a low concentration of pulverized coal using the separate plate and bypass pipe, the mixed fuel injected from the burner nozzle is reduced. Since the pulverized coal concentration can be increased, even when the pulverized coal mill is under low load, it can always maintain the pulverized coal concentration in the appropriate combustion range and achieve stable combustion. % load was the limit, but now it is possible to burn at even lower loads.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is a view taken in the direction indicated by the arrow in FIG. 1. 1 is a pulverized coal burner, 2 is a burner inner cylinder, 3 is a burner outer cylinder, 5 is a mixed fuel introduction part, 6 is a cylindrical flow path,
7 is a burner nozzle, 9 is a separate plate, 1
1 is a bypass pipe, 12 is a flow rate regulating damper, and 13 is a bleed line.

Claims (1)

[Scope of utility model registration request] A pulverized coal burner in which a mixed fuel of pulverized coal and primary air is spirally introduced and ejected from a burner nozzle through a cylindrical flow path between a burner inner cylinder and a burner outer cylinder for combustion. A cylindrical separate plate is arranged between the burner inner and outer cylinders of the introduction part, and the separate plate of the mixed fuel introduction part and the burner inner cylinder are connected to the inside of the furnace via a bleed air line. pulverized coal burner.