An anti-abrasion and material leveling coal feeding device for a circulating fluidized bed

Abstract

The present invention discloses an anti-wear and uniform coal feeding device for a circulating fluidized bed, which solves the problems of how to reduce the impact and wear of coal particles on a uniform coal feeding pipe and how to improve the high concentration of coal particles entering a furnace. A coal conveying air duct (2) is connected to the upper end of the uniform coal feeding pipe (4), the cross section of the pipe section (8) inclined downward gradually changes from a circle to an ellipse, the cross section of the horizontal pipe section (9) is a circle, the cross section of the uniform coal feeding pipe (4) is an ellipse, and a coal conveying air guide plate (3) is provided at the connection between the coal drop pipe (1) and the uniform coal feeding pipe (4), and the coal conveying air guide plate (3) seals the upper half of the inner cavity of the uniform coal feeding pipe (4) above the coal drop port; a uniform coal spreading air duct (6) and a circular coal spreading air duct (5) are provided at the connection between the uniform coal feeding pipe (4) and the water-cooled membrane wall (7) in the furnace. The coal particles are fully burned and the carbon content of the bottom ash is reduced.

Description

Technical Field

[0001] The present invention relates to a circulating fluidized bed boiler, and particularly to a device in the circulating fluidized bed boiler that can effectively prevent the coal feeding pipe from being worn and evenly feed coal to the boiler. Background Art

[0002] The circulating fluidized bed boiler uses coal as fuel. The coal is fed into the furnace of the circulating fluidized bed boiler through a coal feeding device. The coal feeding device is composed of a coal bunker, a coal dropping pipe, a coal conveying air pipe, a material leveling coal feeding pipe, a material leveling coal spreading air pipe, etc. The coal dropping pipe connected to the coal bunker is in a vertically downward state. An inclined material leveling coal feeding pipe is connected to the lower end of the coal dropping pipe. The lower end of the material leveling coal feeding pipe is connected to the water-cooled membrane wall in the furnace. The coal particles in the coal bunker fall vertically through the coal dropping pipe and will directly impact the inner side wall of the obliquely arranged coal feeding pipe. Although there is the action of the coal conveying air from the coal conveying air pipe, due to the limited coal conveying air force, the falling coal particles often cause the inner cavity of the coal feeding pipe at the coal dropping place to be worn faster, and even crack, resulting in air leakage and coal leakage in the coal feeding pipe. In addition, the material leveling coal feeding pipe communicating with the furnace is circular. When the coal passes through the circular coal feeding pipe and enters the furnace, it will cause the coal particles to be too concentrated at the coal feeding place in the furnace, affecting the fluidization of the air distribution plate, resulting in a high carbon content in the burning coal particles and bottom slag, and incomplete combustion of the coal. At the same time, when the moisture content of the coal is high, it is easy to block the coal, causing unstable combustion of the boiler. Therefore, how to reduce the impact and wear of the coal particles on the material leveling coal feeding pipe when the coal particles enter the material leveling coal feeding pipe is a problem that needs to be solved on site. Summary of the Invention

[0003] The present invention provides an anti-wear and material leveling coal feeding device for a circulating fluidized bed, which solves the technical problems of how to reduce the impact and wear of coal particles on the coal feeding pipe, and how to improve the excessive concentration when the coal particles enter the furnace, as well as the blockage and backfire of the coal feeding pipe.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] The general concept of the present invention is as follows: Optimize the shape and structure of the coal conveying air duct, so that under the action of the flow guiding vane, a high-velocity and high-pressure head air cushion of the coal conveying air is formed at the lower part of the inner cavity of the material distributing coal feeding pipe directly below the coal dropping pipe, adhering to the bottom of the material distributing coal feeding pipe. The vertically falling coal particles are driven by this air cushion, changing the direction of their potential energy, preventing the coal particles from directly vertically impacting the inclined material distributing coal feeding pipe, which may cause problems such as increased wear, rupture, air leakage, and coal leakage of the coal feeding pipe. At the same time, the air cushion formed by the coal conveying air creates a negative pressure at the coal dropping port, effectively solving the problems of backfire and flue gas backflow; the material distributing coal feeding pipe adopts an ellipse with a relatively large horizontal width, so that the coal particles entering the furnace are evenly spread, achieving a more uniform coal feeding and more sufficient fluidization effect in the furnace; the coal spreading air duct is designed in a variable cross-section form, so that the coal spreading air enters the furnace in a fan-shaped form, making the coal spreading air more uniform and better fitting the coal feeding pipe, achieving a better coal spreading effect.

[0006] An anti-wear and material distributing coal feeding device for a circulating fluidized bed boiler, comprising a coal bunker, a vertical coal dropping pipe, a coal conveying air duct, a material distributing coal feeding pipe, a material distributing and coal spreading air duct, and a water-cooled membrane wall in the furnace. The lower end of the vertical coal dropping pipe is connected to the upper part of the inclined material distributing coal feeding pipe, the lower end of the material distributing coal feeding pipe is connected to the water-cooled membrane wall in the furnace, a coal conveying air duct is connected to the upper port of the material distributing coal feeding pipe, the coal conveying air duct is in a V shape, and the coal conveying air duct is composed of a horizontal pipe section and an inclined downward pipe section. The cross-section of the inclined downward pipe section gradually changes from a circle to an ellipse along the inclined downward direction, the cross-section of the horizontal pipe section is circular, the cross-section of the material distributing coal feeding pipe is elliptical, a coal conveying air flow guiding vane is arranged at the connection between the coal dropping pipe and the material distributing coal feeding pipe, the coal conveying air flow guiding vane is inclined in the material distributing coal feeding pipe, and the coal conveying air flow guiding vane closes the upper half inner cavity of the material distributing coal feeding pipe above the coal dropping port; a material distributing and coal spreading air duct is arranged at the connection between the material distributing coal feeding pipe and the water-cooled membrane wall in the furnace, the cross-section of the material distributing and coal spreading air duct is elliptical, and the other end of the material distributing and coal spreading air duct is connected to a coal spreading air duct with a circular cross-section through a reduced-diameter connecting pipe.

[0007] A metal bellows expansion joint is arranged on the vertical coal dropping pipe; a viewing hole is arranged on the horizontal pipe section of the coal conveying air duct.

[0008] The present invention effectively reduces the potential energy of the coal particles entering the material distributing coal feeding pipe. Through the design of changing the shapes of the material distributing coal feeding pipe and the coal spreading air duct, the coal particles entering the furnace are fan-shaped distributed for feeding, enabling the coal particles to burn fully and reducing the carbon content in the bottom slag. Brief Description of the Drawings

[0009] Figure 1 is a schematic structural diagram of the present invention;

[0010] Figure 2 is Figure 1 the sectional view taken along the A-A direction in

[0011] Figure 3 is Figure 1 the sectional view taken along line B-B in

[0012] Figure 4 is Figure 1 the sectional view taken along line C-C in

[0013] Figure 5 is Figure 1 the sectional view taken along line D-D in Specific Embodiment

[0014] The present invention will be described in detail below with reference to the accompanying drawings:

[0015] An anti-wear and material-distributing coal feeding device for a circulating fluidized bed boiler, comprising a coal bunker, a vertical coal dropping pipe 1, a coal conveying air pipe 2, a material-distributing coal feeding pipe 4, a material-distributing coal spreading air pipe 6, and a water-cooled membrane wall 7 in the furnace. The lower end of the vertical coal dropping pipe 1 is connected to the upper part of the inclined material-distributing coal feeding pipe 4. The lower end of the material-distributing coal feeding pipe 4 is connected to the water-cooled membrane wall 7 in the furnace. A coal conveying air pipe 2 is connected to the upper port of the material-distributing coal feeding pipe 4. The coal conveying air pipe 2 is in a V shape and is composed of a horizontal pipe section 9 and an inclined downward pipe section 8. The cross-section of the inclined downward pipe section 8 gradually changes from a circle to an ellipse along the inclined downward direction. The cross-section of the horizontal pipe section 9 is circular. The cross-section of the material-distributing coal feeding pipe 4 is elliptical. At the connection between the coal dropping pipe 1 and the material-distributing coal feeding pipe 4, a coal conveying air flow guiding vane 3 is provided. The coal conveying air flow guiding vane 3 is inclined in the material-distributing coal feeding pipe 4 and closes the upper half inner cavity of the material-distributing coal feeding pipe 4 above the coal dropping port. At the connection between the material-distributing coal feeding pipe 4 and the water-cooled membrane wall 7 in the furnace, a material-distributing coal spreading air pipe 6 is provided. The cross-section of the material-distributing coal spreading air pipe 6 is elliptical. The other end of the material-distributing coal spreading air pipe 6 is connected to a coal spreading air pipe 5 with a circular cross-section through a reduced-diameter connecting pipe.

[0016] On the vertical coal dropping pipe 1, a metal bellows expansion joint 10 is provided; on the horizontal pipe section 9 of the coal conveying air pipe 2, a viewing hole 11 is provided.

[0017] The coal conveying air uses secondary hot air. The coal conveying air enters the coal conveying air system of the present invention through the horizontal pipe section 9 of the coal conveying air pipe 2, and successively passes through the coal conveying air circular pipe section, the transition section and the elliptical end of the inclined downward pipe section 8 to change the direction of the coal conveying air; it is connected to the material distributing coal feeding pipe 4 with an elliptical interface through the inclined downward pipe section 8 with a reduced diameter. The cross-section of the coal conveying air gradually changes from circular to elliptical, the transverse plane becomes wider, the cross-sectional area becomes smaller, and the flow velocity increases; after being intercepted by the coal conveying air guide vane 3, the whole coal conveying air is concentrated in the lower half of the elliptical material distributing coal feeding pipe 4, and the flow velocity is further doubled, forming an air flow with a high flow velocity and a high pressure head, preventing coal particles from vertically falling from the vertical coal dropping pipe 1 onto the inner cavity side wall of the material distributing coal feeding pipe 4, avoiding direct impact with the inner cavity of the material distributing coal feeding pipe 4, wearing the material distributing coal feeding pipe 4, and causing phenomena such as air leakage and coal leakage; the material distributing coal feeding pipe 4 is made of elliptical steel pipe, and is divided into two materials up and down. Since the temperature at the junction of the material distributing coal feeding pipe 4 and the water-cooled membrane wall 7 is too high, the end is made of stainless steel material; compared with the conventional coal feeding pipe, the elliptical material distributing coal feeding pipe 4 has a larger transverse dimension, and there are more horizontally arranged coal particles in it, which is conducive to the uniform entry of coal particles into the furnace and plays a role in uniform feeding; the coal spreading air pipe system of the present invention is composed of a circular coal spreading air pipe 5, a reducing pipe and an elliptical material distributing coal spreading air pipe 6, and is arranged horizontally and welded to the end of the material distributing coal feeding pipe 4. The coal spreading air enters the coal spreading air system from the inlet end of the circular coal spreading air pipe 5, and enters the elliptical material distributing coal spreading air pipe 6 through the action of the reducing pipe. At this time, the coal spreading air presents an elliptical cylinder shape with a large horizontal dimension, which is conducive to horizontally dispersing the coal particles and plays a role in uniform spreading and feeding.

Claims

1. An anti-wear and material-equalizing coal feeding device for a circulating fluidized bed boiler, comprising a coal bunker, a vertical coal dropping pipe (1), a coal conveying air pipe (2), a material-equalizing coal feeding pipe (4), a material-equalizing coal spreading air pipe (6), and a water-cooled membrane wall (7) in the furnace. The lower end of the vertical coal dropping pipe (1) is connected to the upper part of the inclined material-equalizing coal feeding pipe (4), and the lower end of the material-equalizing coal feeding pipe (4) is connected to the water-cooled membrane wall (7) in the furnace. It is characterized in that, The upper port of the coal leveling feeding pipe (4) is communicated with a coal conveying air pipe (2). The coal conveying air pipe (2) is in a V shape and is composed of a horizontal pipe section (9) and an inclined downward pipe section (8). The cross-section of the inclined downward pipe section (8) gradually changes from a circle to an ellipse along the inclined downward direction, and the cross-section of the horizontal pipe section (9) is circular. The cross-section of the coal leveling feeding pipe (4) is elliptical. At the connection between the coal dropping pipe (1) and the coal leveling feeding pipe (4), a coal conveying air deflector (3) is provided. The coal conveying air deflector (3) is inclined in the coal leveling feeding pipe (4), and the coal conveying air deflector (3) closes the upper half inner cavity of the coal leveling feeding pipe (4) above the coal dropping port. At the connection between the coal leveling feeding pipe (4) and the water-cooled membrane wall (7) in the furnace, a coal leveling and coal spreading air pipe (6) is provided. The cross-section of the coal leveling and coal spreading air pipe (6) is elliptical, and the other end of the coal leveling and coal spreading air pipe (6) is communicated with a coal spreading air pipe (5) with a circular cross-section through a reducing connecting pipe.

2. The anti-wear and material-equalizing coal feeding device for a circulating fluidized bed boiler according to claim 1, characterized in that, A metal bellows expansion joint (10) is provided on the vertical coal dropping pipe (1); a viewing hole (11) is provided on the horizontal pipe section (9) of the coal conveying air pipe (2).

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