JPH07167421A - Fuel nozzle for fluidized bed boiler - Google Patents

Abstract

PURPOSE:To eliminate agglomeration, caulking of fuel in a nozzle by obviating introduction of fluidizing material and fuel into the nozzle at the time of stopping a boiler. CONSTITUTION:A fluidized bed boiler conveys solid fuel via gas and diffuses it into a furnace from a bottom of the boiler, and comprises a T-shaped fuel inlet 2 provided at a lower part and fuel diffusers 4 provided at upper right and left sides. The diffuser 4 is cut from its bore lower end to an inward deep position at a lower side from a bore upper end 4 of a nozzle outlet in a plane in which an angle formed between a nozzle outlet end face 5 of the diffuser 4 and a horizontal axis of a fuel nozzle becomes an angle theta smaller than an angle of repose alpha of a fluidizing material and fuel particles R Thus, a lower side 11 of a nozzle horizontal tube 3 is so drawn inward as to be shorter than an upper side 12, thereby forming the end face 5 inclined down.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fuel nozzle for a fluidized bed boiler.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional fuel nozzle for a fluidized bed boiler. In FIG. 3, the fuel conveyed from the fuel conveying pipe 1 enters the nozzle through the nozzle inlet 2 at the lower portion of the fuel nozzle having the T-shaped flow passage, and is divided into two directions by the horizontal pipe 3 having the T-shaped flow passage. The fuel is blown into the furnace from the horizontal pipe nozzle outlet 4. In addition, the horizontal pipe nozzle outlet end surface 5 '
Is a plane perpendicular to the horizontal tube 3 (vertical plane).

[0003]

In the conventional fuel nozzle shown in FIG. 3, since the nozzle outlet end face 5'is vertical to the horizontal pipe 3, the fluid material and the fuel 7 in the furnace are stopped in the nozzle when the boiler is stopped. As shown in FIG. 4, a phenomenon occurs in which the fluid material and the fuel 7 enter at an angle of repose α and close the nozzle outlet 4. At the time of a boiler trip, since the inside of the furnace is at a high temperature, the fuel that has entered the nozzle due to the heat causes agglomeration and coking and is fixed at the nozzle outlet 4, which may prevent restarting. The present invention provides a fuel nozzle in which agglomeration or coking does not occur in the fuel nozzle and solves the above-mentioned conventional problems.

[0004]

For this reason, the present invention is a fluidized bed boiler in which a solid fuel is conveyed by gas and blown into the furnace from the bottom of the boiler, and has a T-shape and has a fuel inlet at the bottom, Fuel outlets are provided on the left and right of the upper part, and the outlets are flat so that the angle with the horizontal axis of the fuel nozzle is less than or equal to the repose angle of the fluid and fuel particles. The nozzle outlet end surface is formed by cutting from the lower end portion of the outlet inner diameter to a deep position inside and forming a nozzle outlet end surface that inclines downward. This is a means for solving the problem.

[0005]

According to the present invention, the angle between the end face of the fuel nozzle outlet and the horizontal axis of the fuel nozzle is equal to or less than the angle of repose of the fluid material and the fuel particles, and the inner diameter of the nozzle outlet from the lower end to the nozzle inner diameter. By cutting from the lower end to the deep inside position, even if the gas blown out from the nozzle is stopped when the boiler is stopped, fluid material and fuel do not fall and enter the nozzle without accumulating. The fuel can be restarted without fuel agglomeration or coking.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. First, in FIG. 5 showing a general fuel supply system diagram of a fluidized bed boiler, the fuel supplied from the fuel carrier pipe 1 enters the fuel nozzle from the fuel nozzle inlet 2 provided at the bottom of the fluidized bed boiler 9, It is branched by the horizontal pipe 3 in the fuel nozzle and blown into the furnace from the fuel nozzle outlet 4. In FIG. 5, 8 is a fuel cutoff valve and 10 is a fluidized bed. The lower end 11 of the nozzle horizontal pipe 3 is made shorter than the upper end 12 by cutting the lower side of the fuel nozzle outlet end surface 5 obliquely from the nozzle outlet inner diameter upper end portion 6 to a deep position inward from the nozzle outlet inner diameter lower end portion. The angle θ formed between the nozzle outlet end surface 5 and the horizontal axis of the fuel nozzle is set to be equal to or less than the repose angle α of the fluid material and the fuel particles 7 so as to be inward. As a result, the fluid material and the fuel 7 cannot be deposited in the state of the angle of repose α as shown in FIG. 4, and the fluid material and the fuel 7 do not drop downward and block the nozzle outlet 4.

[0007]

As described above in detail, according to the present invention, even when the boiler is stopped, the end face of the fuel nozzle is a plane having an angle less than the repose angle of the fluid and the fuel particles from the horizontal axis of the fuel nozzle. Since the lower end of the nozzle is cut from the lower end of the inner diameter of the nozzle outlet to a deeper position inward, an outlet end face that slopes downward is formed, so that fluid material and fuel do not enter the fuel nozzle and There is no ration or caulking.

[Brief description of drawings]

FIG. 1 is a sectional view of a fuel nozzle according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an outlet portion of the fuel nozzle of FIG. 1 and an explanatory view of effects.

FIG. 3 is a sectional view of a conventional fuel nozzle.

FIG. 4 is an explanatory diagram showing a state of a conventional fuel nozzle when a boiler is stopped.

FIG. 5 is a system diagram of fuel supply for a fluidized bed boiler.

[Explanation of symbols]

 1 Fuel Conveying Pipe 2 Nozzle Inlet 3 Horizontal Pipe 4 Nozzle Outlet 5 Nozzle Outlet End Face 6 Nozzle Outlet Inner Diameter Upper End 7 Fluid Material and Fuel

Claims (1)

[Claims] 1. A fluidized bed boiler that conveys solid fuel by gas and blows it into the furnace from the bottom of the boiler, has a T shape, has a fuel inlet at the bottom, and has fuel outlets at the upper and left sides, The outlet is a plane such that the angle with the horizontal axis of the fuel nozzle is less than or equal to the angle of repose of the fluid material and the fuel particles, and the position is deep from the upper end of the nozzle outlet inner diameter to the lower side and from the lower end of the nozzle outlet inner diameter to the inside. A fuel nozzle for a fluidized bed boiler, characterized in that an end face of a nozzle outlet is formed by cutting up to the end.