JPH0341725B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a method for supplying granular materials such as coal or limestone, gas or atomized liquid fuel (hereinafter referred to as This relates to a fuel conveying nozzle that supplies fuel (referred to as fuel) by air conveyance.

[Conventional technology]

BACKGROUND OF THE INVENTION As shown in FIG. 1, a fuel conveying nozzle used in a conventional fluidized bed combustion apparatus generally has a cross-shaped upper end branched horizontally, and is always open. In such a fuel conveying nozzle 1, when the fuel conveyance is stopped and the conveying air is also stopped, the fluidized medium in the fluidized bed 2 flows back into the conveying nozzle 1, and eventually the inside of the conveying pipe 3 flows backward and falls. Filled with fluid medium. When reusing the fuel conveying nozzle in which the fluidized medium has flowed back, it is necessary to push the filled fluidic medium back into the fluidized bed 2, and for this purpose, a pressure of 0.6 to 1.0 Kg/cm ² G is usually required. It is.
This exceeds the blower pressure of the conveying air.

Therefore, in order to restart the engine, a purge system is provided which combines a compressed air supply pipe 4 and solenoid valves 5 and 6, as shown in FIG. If such a purge system is applied to a large fluidized bed combustion device, such as a fluidized bed boiler, the number of fuel conveyance pipes is extremely large, requiring excessive capital investment. Even when it is necessary to promptly start coal feeding operations, such as the above, there is a problem in that a lot of wasted time is required. Note that 7 is an air distribution plate, 8 is a wind box, 10 is a fluidized combustion air supply pipe, and 11 is a heat transfer tube.

In order to solve the above-mentioned problems, the present applicant has already published Japanese Patent Application No. 58-111653 (Japanese Unexamined Patent Publication No. 60-2804) to cover the outer periphery of the upper end of the conveying pipe with intervals. The present invention has been applied for a fuel conveying nozzle in which an outer cylinder having an opening only at the bottom is fixed to the conveying pipe coaxially with the conveying pipe via a support member, and a flow prevention plate is provided around the conveying pipe below the opening of the outer cylinder. There is. However, the following problems still remain in the fuel conveying nozzle of this prior application.

[Problem to be solved by the invention]

In a normal fluidized bed furnace, during operation, the fluidized medium that forms the fluidized bed is agitated within the fluidized bed in a state similar to the boiling phenomenon of water, and is maintained at a high temperature necessary to sustain fuel combustion. ing. Therefore, since the outer surface of the outer cylinder is always in contact with this high-temperature fluid medium, the outer cylinder itself has a high temperature close to that of the fluid medium. In addition, at the opening at the bottom end of the outer cylinder, the high temperature fluid medium flows in a pulsating state into the fuel flow path inside the outer cylinder due to the effects of the bubbles of the fluidizing air sent from the air distribution plate at the bottom of the fluidized bed and the agitation of the fluidizing medium. This is a state in which the phenomena of entering and being pushed out by the conveying air are repeated alternately.

Therefore, when the above-mentioned fuel conveyance nozzle is placed in such an environment, when the fuel passes through the conveyance pipe and reaches the fluidized bed from the inner surface flow path of the outer cylinder, a part of the fuel is lost inside the fluidized bed. Before reaching the temperature, combustion occurs on the inner wall surface of the outer cylinder and the opening at the lower end of the outer cylinder, and the embers and unburned substances adhere to the inner wall surface of the outer cylinder and the outer wall surface of the conveying tube. These stuck objects reduce the area of the combustion flow path and increase the inflow resistance of carrier air and fuel, which further worsens the flow and increases the amount of stuck objects, eventually causing partial blockage. It has been experimentally confirmed that This is considered to be due to the following two points in the above-mentioned fuel conveyance nozzle.

(1) The outer cylinder is in direct contact with the high-temperature fluid medium.

(2) The flow prevention plate installed below the outer cylinder is installed horizontally near the opening of the outer cylinder so as to bend the outflowing fuel at right angles, increasing the outflow resistance. This prevents the rapid removal of the flowing medium that enters in a pulsating manner.

The present invention has been made in view of the above points, and includes a protective tube provided outside the outer tube so as to create a gap to prevent the outer tube from coming into contact with a high-temperature fluid medium and increasing its temperature. It is an object of the present invention to provide a fuel conveying nozzle as described above.

[Means and actions to solve the problem]

In order to achieve the above object, the fuel conveying nozzle to the fluidized bed combustion apparatus of the first invention of the present application has a second
3 and 6, a wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7, and fuels are distributed. In a fluidized bed combustion apparatus in which the upper end of the conveying pipe 3 for conveying air flow is located at the lower part of the fluidized bed 2, an outer structure having an opening 12 only in the lower part so as to cover the outer periphery of the upper end of the conveying pipe 3 with a gap is provided. The tube 13 is coaxially fixed to the transfer tube 3 via a support member 14, and a protective tube 15 is provided outside the outer tube 13 so that a gap 16 is formed.

Moreover, the fuel conveying nozzle of the second invention of the present application is
If explained with reference to FIGS. 2, 5, and 8,
A wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7, and the upper end of a conveying pipe 3 for airflowing fuels is located in the lower part of the fluidized bed 2. In the fluidized bed combustion apparatus, an outer cylinder 13 having an opening 12 only at the bottom is provided with a supporting member 14 coaxially with the transport pipe 3 so as to cover the outer periphery of the upper end of the transport pipe 3 with a gap. A protective tube 15 is provided outside the outer tube 13 so that a gap 16 is formed between the outer tube 13 and the protective tube 1.
5 is characterized in that a gap 16 between the two is filled with a heat insulating material 21.

Further, the fuel conveying nozzle of the third invention of the present application is
To explain with reference to FIGS. 2, 3, and 6,
A wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7, and the upper end of a conveying pipe 3 for airflowing fuels is located in the lower part of the fluidized bed 2. In the fluidized bed combustion apparatus, an outer cylinder 13 having an opening 12 only at the bottom is attached coaxially to the transport pipe 3 via a support member 14 so as to cover the outer periphery of the upper end of the transport pipe 3 with a gap. A protection tube 15 is provided outside the outer tube 13 so that a gap 16 is formed, and a conical portion is placed at the upper part and this conical portion at the lower portion around the conveying tube 3 below the opening 12 of the outer tube 13. It is characterized by the provision of a fuel outflow guide ring 17 having a wider curved surface.

In the first, second, and third inventions,
As shown in FIGS. 6 and 8, respectively, it is desirable to fix the support member 14a obliquely to the axis of the conveying tube 3.

With these configurations, it is possible to prevent the outer cylinder 13 from coming into direct contact with the high-temperature fluid medium, thereby preventing fuel from sticking to the opening at the lower end of the outer cylinder 13 and clogging the outer cylinder 13 and the protective cylinder 15. air gap 16 between
When the heat insulating material 21 is filled in the outer cylinder 13, the effect of lowering the temperature of the outer cylinder 13 can be further increased.Furthermore, the fuel outflow guide ring 17, which has a conical upper part and a curved part wider than the conical part at the lower part, can be used. If provided, fuel can flow out smoothly.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 2 to 4 show an embodiment of the fuel conveying nozzle of the present invention. The fluidized bed combustion apparatus shown in FIG. 2 has a wind box 8 at the bottom, as in the case of FIG. 1, and a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7. A heat exchanger tube 11 is inserted into the fluidized bed 2 as necessary, and the upper end of the conveying tube 3 for airflow conveying fuels is positioned at the lower part of the fluidized bed 2. An outer cylinder 13 having an opening 12 only at the bottom is fixed coaxially to the conveying tube 3 via a support member 14 so as to cover the outer periphery of the upper end of the conveying tube 3 with a gap, A protection tube 15 is provided outside the outer tube 13 with a gap 16 therebetween. The conveying tube 3 is inserted into the outer tube 13 so that the angle α between the lower inner edge of the outer tube 13 and the upper outer edge of the conveying tube 3 is 25 to 3 degrees, preferably 12 to 5 degrees.
When the angle α exceeds 25 degrees, the fluid medium tends to flow back into the conveyor pipe 3. On the other hand, when the angle α is less than 3 degrees, it is difficult for the fluid medium to flow back into the conveyor pipe 3, but it flows outside the conveyor pipe 3. Since the length of insertion into the cylinder 13 becomes very long, the fuel conveying nozzle becomes large, causing problems such as the possibility of burning out the installation space and an increase in pressure loss.

Furthermore, in order to more reliably prevent the fuel flowing out from the outer cylinder 13 from coming into contact with a high-temperature fluid medium and burning inside and sticking to the inner wall of the outer cylinder 13, the outer cylinder 13 has a curved surface with respect to the horizontal, and as it goes toward the top, Further, a fuel outflow guide ring 17 having an angled conical shape, that is, a fuel outflow guide ring consisting of a conical part at the upper part and a curved part wider than the conical part at the lower part, is conveyed to the lower side of the opening 12 of the outer cylinder 13. Provided around the tube 3.

By providing a guide ring having a shape that combines a conical portion and a curved surface portion in this way, it is possible to prevent flow and serve as a fuel inflow guide. 1
8 is a fixing member for fixing the protection tube 15 to the outer tube 13, and 20 is a spacing plate for keeping the gap between the protection tube 15 and the outer tube 13 constant.

In addition, as shown in FIG. 5, the outer cylinder 13 and the protective cylinder 1
Fill the gap between the heat insulating material 21 and the
In some cases, the effect of lowering the temperature of the outer cylinder 13 more reliably may be increased. In this case, the spacing plate 20
also serves as a closing plate to prevent the insulation material from falling.

6 and 7 show other embodiments of the invention. That is, by fixing the support member 14a obliquely to the axis of the transport pipe 3, the airflow is forced to swirl. Therefore, non-uniform resistance occurs when the fuel flows out due to the pulsating fluid medium that partially enters through the opening 12 at the lower end of the outer cylinder 13, and swirls are given to the conveying air flow to smooth out the fluid medium that partially enters. can do.

In addition, as shown in FIG. 8, the outer cylinder 13 and the protective cylinder 1
Filling the gap between 5 and 5 with heat-resistant preservation material 21,
In some cases, the effect of lowering the temperature of the outer cylinder 13 more reliably may be increased. In this case, the spacing plate 2
0 also serves as a closing plate to prevent the heat insulating material from falling.

〔Effect of the invention〕

As explained above, the fuel conveying nozzle of the present invention is further provided with a protective cylinder on the outside of the outer cylinder so that a gap is created, so that the outer cylinder is prevented from coming into direct contact with the high-temperature fluid medium. This can prevent fuel from sticking and clogging at the opening at the bottom end of the cylinder, and if the gap between the outer cylinder and the protective cylinder is filled with heat insulating material, the effect of lowering the temperature of the outer cylinder can be further increased. In addition, when a fuel outflow guide ring is provided, the upper part of which is a conical part and the lower part of which is a curved part that is wider than the conical part, the fuel can flow out smoothly.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a fuel conveying nozzle in a conventional fluidized bed combustion apparatus, FIG. 2 is an explanatory diagram showing an example of a fuel conveying nozzle for a fluidized bed combustion apparatus of the present invention, and FIG. An enlarged vertical sectional view of the fuel conveying nozzle shown in FIG. 2, and FIG. 4 is an A--A in FIG.
5 is a longitudinal sectional view showing a nozzle in which the gap is filled with a heat insulating material in the fuel conveying nozzle of FIG. 3, and FIG. 6 is a longitudinal sectional view showing another embodiment of the fuel conveying nozzle of the present invention. 7 is a sectional view taken along the line B--B in FIG. 6, and FIG. 8 is a longitudinal sectional view showing a nozzle in which the intervals in the fuel conveying nozzle of FIG. 6 are filled with heat insulating material. 1...Fuel conveying nozzle, 2...Fluidized bed, 3...
Conveying pipe, 4...Compressed air supply pipe, 5, 6...Solenoid valve, 7...Air distribution plate, 8...Wind box, 10...Air supply pipe for fluidized combustion, 11...Heat transfer tube, 12... …
Opening, 13...Outer tube, 14, 14a...Support member, 15...Protection tube, 16...Gap, 17...Fuel outflow guide ring, 18...Fixing member, 20...
...Spacer holding plate, 21...Heat insulation material.

Claims (1)

[Claims] 1. A wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air dispersion plate 7, and the upper end of a conveying pipe 3 for air-flowing fuels is fluidized. In a fluidized bed combustion apparatus located in the lower part of the layer 2, an outer cylinder 13 having an opening 12 only at the bottom is conveyed coaxially with the conveying pipe 3 so as to cover the outer periphery of the upper end of the conveying pipe 3 with a gap. A fuel conveying nozzle for a fluidized bed combustion apparatus, characterized in that it is fixed to a pipe 3 via a support member 14, and a protective cylinder 15 is provided outside the outer cylinder 13 so that a gap 16 is formed. 2. A fuel transfer nozzle for a fluidized bed combustion apparatus according to claim 1, in which the support member 14a is fixed obliquely to the axis of the transfer pipe 3. 3. A wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7, and the upper end of the conveying pipe 3 for airflow conveying the fuel is located at the lower part of the fluidized bed 2. In the fluidized bed combustion apparatus, an outer cylinder 13 having an opening 12 only at the bottom is attached to the carrier pipe 3 coaxially with a support member 14 so as to cover the outer periphery of the upper end of the carrier pipe 3 with a gap. A protective tube 15 is provided outside the outer tube 13 so that a gap 16 is formed between the outer tube 13 and the protective tube 1.
5. A fuel conveying nozzle for a fluidized bed combustion apparatus, characterized in that a gap 16 between the fuel and the fluidized bed combustion apparatus is filled with a heat insulating material 21. 4. A fuel transfer nozzle for a fluidized bed combustion apparatus according to claim 3, in which the support member 14a is fixed obliquely to the axis of the transfer pipe 3. 5 A wind box 8 is provided at the bottom, a fluidized bed 2 is formed above the wind box 8 via an air distribution plate 7, and the upper end of the conveying pipe 3 for airflow conveying the fuel is located at the lower part of the fluidized bed 2. In the fluidized bed combustion apparatus, an outer cylinder 13 having an opening 12 only at the bottom is attached to the carrier pipe 3 coaxially with a support member 14 so as to cover the outer periphery of the upper end of the carrier pipe 3 with a gap. A protective tube 15 is provided outside the outer tube 13 so that a gap 16 is formed, and the opening 12 of the outer tube 13 is fixed.
Fuel conveyance to a fluidized bed combustion apparatus characterized in that a fuel outflow guide ring 17 having a conical upper part and a curved part wider than the conical lower part is provided around the lower conveying pipe 3. nozzle. 6. A fuel transfer nozzle for a fluidized bed combustion apparatus according to claim 5, in which the support member 14a is fixed obliquely to the axis of the transfer pipe 3.