JP2617322B2 - Dispersion plate nozzle for fluidized bed combustor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustion apparatus, and more particularly, to a fluidized bed combustion apparatus suitable for reducing falling of a fluidized medium from a nozzle hole for supplying fluidized air. The present invention relates to a dispersion plate nozzle for an apparatus.

[Conventional technology]

Fluidized bed incinerators have advantages such as a wide range of applications to fuel, in-furnace desulfurization, and high heat transfer performance in a bed, and are suitably used as coal-fired boilers and the like.

As shown in FIG. 2, the conventional apparatus is provided with a fluidized bed using limestone as the fluidized medium 3 and containing desulfurizing agent particles.
The mixture of lime and limestone supplied from a crushed coal bunker and a limestone bunker not shown is 800 to 8 in a fluidized bed.
It is burned at 20 ° C, and the boiler is heated by the combustion energy to generate the required quality steam. However, in the fluidized bed combustion apparatus, consideration is given to the point that the fluidized medium 3 in the fluidized bed flows backward through the nozzle hole 11 of the dispersion plate nozzle 8 shown in FIG. Had not been. The diameter of the nozzle hole 11 of the conventional dispersion plate nozzle 8 is 4 mm, and the average diameter of the fluid medium 3 is 1 to 2 mm. In particular, in the starting cell in which the hot air stove 7 is installed, the amount of air during starting using the light oil burner for starting and the amount of air during normal flowing after extinguishing the burner are greatly different. The pressure difference between the inside (supply side) and outside of the nozzle hole 11 of the plate nozzle 8 becomes small, and when starting and stopping the fluidized bed, the carrier air in the coal feed pipe 5 flows before the fluidizing air and then stops. Therefore, the carrier air is pressurized by the conventional dispersion plate nozzle 8, and the flowing medium 3 flows backward from the nozzle hole 11 and
And the wind box 9 becomes full, making it impossible to continue the operation. This is an important problem that must be solved before the fluidized bed combustion apparatus is increased in size, and is one of the urgent problems.

In U.S. Pat.No. 3,520,033 and Japanese Patent Application No. 30-1217, a plurality of stages of non-circular cross-section nozzle holes or circular cross-section nozzle holes or short tubes provided radially or circumferentially from the center of the nozzle are inserted. Although the disclosed nozzle holes are disclosed, all the nozzle holes have the same inner and outer opening areas, and are expected to have the above-mentioned problems.

[Problems to be solved by the invention]

In the prior art, no consideration is given to preventing backflow of the flowing medium from the nozzle hole of the dispersion plate nozzle,
There was a problem that the flow medium was back-flow deposited on the wind box and it became impossible to continue the operation.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dispersion plate nozzle for a fluidized bed combustor which prevents backflow of a fluid medium from a nozzle hole of the dispersion plate nozzle.

[Means for solving the problem]

In order to achieve the above object, a dispersion plate nozzle for a fluidized bed combustion device according to the present invention is a dispersion plate nozzle for a fluidized bed combustion device having a nozzle hole for supplying fluidizing air, wherein the nozzle hole is formed as an inner hole. In this configuration, the cross-sectional area is formed in a conical divergent shape smaller than the outer hole cross-sectional area.

[Action]

According to the present invention, when the dispersing plate nozzle holes for supplying fluidizing air to the fluidized bed are divergent and the inside has an area smaller than the outside, and when the differential pressure between the outside and the inside is reduced,
Alternatively, when the fluid for air flowing from the inside disappears and the pressure from the outside is applied, the fluid medium in the fluidized bed flows in from the outside of the nozzle hole, but the flow velocity increases in the small area inside. As a result of the flow contraction, the passage area is further reduced, and the flow velocity gradually increases toward the inside, that is, the pressure decreases, causing turbulence, etc., and the so-called wedge effect (material lock of the flow medium) causes the nozzle hole to be closed. The flowing medium does not flow backward and fall into the wind box.

〔Example〕

One embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 2, a wind box 9 is provided, which is surrounded by a furnace wall 2 and is partitioned by a water pipe with a membrane 6 forming a furnace bottom thereof. 7 is connected. A coal feed pipe 5 for supplying one fuel into a fluidized bed in which the fluidized medium 3 flows and burns is provided through a plurality of water pipes 6 with membranes and a partition plate connecting them, and the other fluidized air is supplied to the fluidized bed. The supply nozzle hole 10 is configured so as to include a dispersion plate nozzle 4 that is divergent and has an inner (supply side) area smaller than the outside.

The flow of the flowing air is pressurized by a not-shown forced draft fan, is heated by an air preheater on the way, is injected from the wind box 9 into the fluidized bed through the nozzle holes 10 of the dispersion plate nozzle 4, and is fed into the fluidized bed. 3 serves to make 3 flow.
The startup hot blast furnace 7 is a furnace for heating the fluidized medium 3 to 500 to 600 ° C. at startup.

In the above-described configuration, in the conventional dispersion plate nozzle 8 of FIG. 3, the nozzle hole diameter is 4 mm, and the average particle diameter of the fluid medium 3 is 1 to 2 mm. Inside, the pressure difference between the inside and outside of the dispersion plate nozzle becomes small. Also, when starting and stopping the fluidized bed, the conveying air in the coal feeding pipe 5 is caused to flow before the flowing air in order to prevent the flowing medium 3 from flowing back into the coal feeding pipe 5 and then stopped, so that the conveying air is dispersed. There is a problem that the fluid medium 3 drops and accumulates in the wind box 9 due to conditions such as pressurization of the plate nozzle 4 and the operation cannot be continued. However, as in the dispersion plate nozzle 4 shown in FIG. When the pressure difference across the dispersion plate nozzle 4 is reduced by making the shape of the nozzle hole 10 a flared flared shape (conical shape) with a slope of 30 to 35 °, or unilaterally, the flow from the inside of the dispersion plate nozzle 4 Even when there is no working air and pressure is applied from the outside, the fluidized medium 3 in the fluidized bed operates so as to lock the material by the wedge effect by the trumpet-shaped dispersion plate nozzle 4. In other words, the flowing medium 3 which has flowed in reverse from the outside of the nozzle hole 10 increases the flow velocity inside the small area and generates a contraction. As a result, the passage area is further reduced, and the flow velocity gradually increases from the outside to the inside. As a result, the pressure is reduced and turbulence is generated, so that the flowing medium 3 is stuck in the narrowed portion and does not drop into the wind box 9.

Further, as shown in FIG. 1b, it is assumed that a plurality of nozzle holes 10 of the dispersion plate nozzle 4 are arranged in two stages on the circumference and are alternately arranged in each row.

As another embodiment of the present invention, as shown in FIG. 1c, a shape obtained by combining a small diameter cylindrical shape inside the nozzle hole 10 and a trumpet shape outside the nozzle hole 10, similar to the nozzle hole shape in FIG. 1a. The effect of preventing the backflow of the fluid medium is obtained.

〔The invention's effect〕

According to the present invention, the nozzle hole for supplying the air for flow has a conical divergent shape, and the inner hole cross-sectional area is smaller than the outer hole cross-sectional area. As a result, the flow velocity of the fluid medium is increased to cause material lock and prevent the fluid medium from flowing backward. When the inner pressure increases, the material-locked fluid medium is instantaneously removed to the outside along the divergent surface. Under all operating conditions, the backflow of the fluidized medium in the fluidized bed into the wind box can be prevented, and the accumulation of the fluidized medium in the wind box can be prevented, so that operation is not interrupted and long-term stable operation of the fluidized bed combustion device is possible. Becomes

[Brief description of the drawings]

1a is a sectional view of a dispersion plate nozzle showing one embodiment of the present invention, FIG. 1b is a perspective view of FIG. 1a, FIG. 1c is a partial sectional view showing another embodiment of the present invention, FIG. FIG. 1 is a cross-sectional view of a fluidized bed combustion apparatus, and FIG. 3 is a cross-sectional view of a dividing plate nozzle showing a conventional technique. 3 ... fluid medium, 4 ... dispersion plate nozzle, 10 ... nozzle hole.

Claims (1)

(57) [Claims] 1. A dispersing plate nozzle for a fluidized bed combustion device having a nozzle hole for supplying air for flow, wherein the nozzle hole is formed to have a conical divergent shape with an inner hole sectional area smaller than an outer hole sectional area. Dispersion plate nozzle for a fluidized bed combustion apparatus, characterized in that: