JP2781222B2 - Pulverized coal combustion equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulverized coal combustion apparatus, and more particularly to a pulverized coal combustion apparatus suitable for improving flame stability.

[Conventional technology]

In a conventional pulverized coal combustion apparatus, for example, as shown in FIG. 5, in order to prevent flashback from the tip of the burner, a venturi is provided in the primary air sleeve 11 to increase the flow velocity of the conveying air in the pulverized coal supply line. 15 were provided. However, due to the action of the venturi 15, the flow of air and pulverized coal is reduced by one.
The concentration of pulverized coal near the flame holding ring 6 provided at the discharge end of pulverized coal gathers at the center of the next air sleeve 11 to improve the flame holding property and obtain a stable flame (particularly at low load). No consideration was given to it.

For this reason, the present inventors, in Japanese Utility Model Laid-Open No. 63-23516, provided a pulverized coal guide member downstream of the venturi in the pulverized coal supply pipeline so that the pulverized coal concentration becomes high near the pipe wall, In addition, a pulverized coal feeder is proposed in which the flow rate of air in the radial direction of the pipeline is substantially constant by the rectifying member. However, when the pulverized coal concentration during low load combustion is low, the point of adjusting the pulverized coal concentration to an effective concentration and improving the flame holding properties to obtain a stable flame is still sufficiently satisfactory. Was not.

[Problems to be solved by the invention]

As described above, in the prior art, the drift of the pulverized coal by the venturi provided in the pipe that supplies the pulverized coal together with the primary air, that is, the pulverized coal concentration near the center of the primary air sleeve increases, thereby increasing the pulverized coal concentration. As a result, the concentration of pulverized coal near the inner wall of the primary air sleeve is reduced, and no consideration is given to supplying an effective concentration of pulverized coal to the vicinity of the flame holding ring required for initial ignition. When loaded (when the pulverized coal concentration of the pulverized coal supply air-fuel mixture is low), the flame holding properties are not sufficient and there is a problem.

An object of the present invention is to reduce the pulverized coal concentration by effectively adjusting the air flow rate and the pulverized coal concentration at the discharge end of the pulverized coal supply pipe even at a low load, and eliminating the problems in the prior art. Even in such a case, it is an object of the present invention to provide a pulverized coal combustion apparatus which improves the flame holding property of a burner and stabilizes a flame.

[Means for solving the problem]

The object of the present invention is to provide a pulverized coal classification element whose installation position can be adjusted in a pulverized coal supply pipe, and a guide pipe that makes the air flow velocity in the pipe radial direction substantially constant, so that the pulverized coal concentration is reduced. By adjusting the installation position of the classifying element even in a low case, the air flow velocity distribution in the radial direction of the pipeline and the pulverized coal concentration distribution can be adjusted to an optimum state by providing a pulverized coal supply device. Achieved.

According to a first aspect of the present invention, there is provided a pulverized coal combustion apparatus having a pipe for conveying pulverized coal by air, supplying the pulverized coal to a pulverized coal burner, and burning the pulverized coal. From the upstream side of the pulverized coal discharge end, a classification element and a guide cylinder are provided to maintain the pulverized coal concentration distribution in the radial direction of the pipe up to the pulverized coal discharge end of the pipe, and the radius of the pipe Coal pulverized combustion device provided with a structure in which the installation position can be freely adjusted in the direction of the central axis of the pipeline so that the air velocity distribution in the direction is substantially constant at the pulverized coal discharge end of the pipeline. It is assumed that.

Further, according to the present invention, as described in claim 2, in the pulverized coal combustion device of claim 1, the pulverized coal classification element includes:
On the support provided in the center axis direction of the pulverized coal supply pipeline,
The pulverized coal combustion device has a structure in which the classification element is slid by a slide lever mechanism so that the installation position of the classification element can be freely adjusted.

[Action]

Even if the pulverized coal concentration is low, the airflow distribution is uniform and the mixture with an increased pulverized coal concentration is supplied to the vicinity of the flame holding ring by freely adjusting the installation position of the pulverized coal classification element. Can be. As a result, the concentration of pulverized coal required for ignition in the vicinity of the flame holding ring can be secured, and a stable pulverized coal flame can be obtained.

〔Example〕

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

FIG. 1 is a sectional view showing an example of the configuration of a pulverized coal burner to which the pulverized coal supply device of the present invention is applied. In the figure, 1
Pulverized coal flow conveyed in the pulverized coal supply pipe with secondary air
Reference numeral 12 denotes primary air and pulverized coal that collided with the block-shaped pulverized coal classification element 10 provided on the distance piece 8 at the center in the primary air sleeve 11 of the burner along the inner wall of the primary air sleeve 11. It becomes a flow and the classification element 10
The primary air flow velocity is recovered uniformly in the cross-sectional direction by the smooth taper on the downstream side of the pulverized coal. However, the pulverized coal having a larger momentum than this primary air flow is maintained by maintaining the flow along the inner wall. First, the pulverized coal concentration on the inner wall side of the primary air sleeve 11 can be increased.

However, as it is, before reaching the flame holding ring 6 attached to the pulverized coal discharging end of the primary air sleeve 11, the pulverized coal concentration distribution is made uniform, and high concentration pulverized coal is supplied near the flame holding ring 6. Classifying element
10 Ideal concentration distribution in the wake (air velocity is uniform,
A guide cylinder 7 is provided to maintain the pulverized coal concentration at the center and low at the center of the pipe wall) to the position of the flame holding ring 6 as it is. Thereby, the pulverized coal concentration in the vicinity of the flame holding ring 6 is increased, the initial ignitability of the pulverized coal is improved, and stable flame holding becomes possible.

Further, the classifying element 10 has a structure that can slide on the distance piece 8.
This is shown in FIGS. 3, 3 and 4.

FIG. 2 shows a case where the distance between the classification element 10 and the guide cylinder 7 is increased. In this case, the pulverized coal concentration distribution and the air velocity distribution on the downstream side of the classification element 10 are made uniform, and No effect. Conversely, as shown in FIG. 4, when the classification element 10 is brought too close to the guide cylinder 7, an ideal concentration distribution is obtained when only the pulverized coal concentration distribution is taken, but the air flow velocity distribution is as follows. The inner wall side of the primary air sleeve 11 becomes faster, hindering the generation of minute vortices necessary for ignition generated on the downstream side of the flame holding ring 6, and as a result, the flame holding property is reduced.

That is, by adjusting the positional relationship between the classifying element 10 and the guide cylinder 7 to an optimum position, even if the pulverized coal concentration becomes low at a low load, as shown in FIG. A distribution can be obtained.

In the above embodiment, the pulverized coal burner having the flame holding ring 6 at the end of the primary air sleeve 11 has been described. However, the effect of this embodiment can be applied to a pulverized coal burner without a flame holding ring.

〔The invention's effect〕

As described in detail above, the pulverized coal burner provided with the pulverized coal combustion device of the present invention is provided with a pulverized coal classification element and an air flow guide cylinder in the pulverized coal supply line, and a pulverized coal classification element. By adjusting the position, the pulverized coal concentration distribution and the air flow velocity distribution at the discharge end of the pulverized coal can be optimally controlled, and the following effects can be obtained.

(1) As a new function added to the pulverized coal burner, the ignition and flame holding properties are improved by adjusting the pulverized coal concentration distribution at the pulverized coal discharge end.

(2) As an improvement in the performance and efficiency of the pulverized coal burner, it is possible to stabilize the flame during low load combustion of the burner.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a pulverized coal burner exemplified in an embodiment of the present invention, and FIGS. 2, 3 and 4 show positions of a classification element of a pulverized coal supply line of the pulverized coal burner of FIG. Fig. 5 is a schematic diagram showing a pulverized coal concentration distribution and an air flow velocity distribution at a pulverized coal discharge end when the air temperature is changed. It is a schematic diagram which shows a distribution and an air flow velocity distribution. 1 ... wind box, 2 ... secondary air register 3 ... tertiary air register 4, ... burner throat 5 ... secondary air vane, 6 ... flame holding ring 7 ... guide cylinder, 8 ... distance Piece 9: Slide lever, 10: Classifying element 11: Primary air sleeve 12: Pulverized coal flow, 13: Pulverized coal (high concentration) 14: Pulverized coal (low concentration) 15: Venturi, 16 ...... Ignition torch

Continuation of the front page (72) Inventor Tadashi Jimbo 6-9 Takara-cho, Kure City, Hiroshima Prefecture Inside the Kure Factory of Babcock Hitachi, Ltd. (56) References Bikai 1-136218 (JP, U) (58) Fields surveyed (Int.Cl. ⁶ , DB name) F23D 1/00

Claims (2)

(57) [Claims] 1. A pulverized coal combustion apparatus having a pipe for conveying pulverized coal by air, supplying the pulverized coal to a pulverized coal burner, and burning the pulverized coal. A guide cylinder is provided, and the classification element is provided in a structure capable of adjusting the pulverized coal concentration distribution in the radial direction of the pipeline, and the guide cylinder is configured to adjust the pulverized coal concentration distribution in the radial direction of the pipeline by the classification element of the pipeline. A pulverized coal combustion apparatus characterized in that it is provided so as to maintain the pulverized coal discharge end. 2. The pulverized coal combustion apparatus according to claim 1, wherein the classifying element is provided in a structure in which the installation position can be freely adjusted in the flow direction of air and pulverized coal in the pipeline. Pulverized coal combustion equipment.