JPH0128285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a fluidized bed combustion apparatus, and more particularly to a method of operating a fluidized bed combustion apparatus that can easily change the load of a combustion apparatus having heat transfer tubes in the fluidized bed. be.

In a combustion device that has heat transfer tubes in the fluidized bed, such as a fluidized bed boiler, when the amount of fuel supplied is reduced to reduce the boiler load, the effect of the amount of absorbed heat due to the heat transfer tubes in the bed is reduced. This has the disadvantage that the thermal balance is disrupted and the layer temperature drops significantly. On the other hand, there is a lower limit to the bed temperature for stable combustion in the fluidized bed, and due to this limit, the load change range is generally narrow, 100 to 70%, and there is a problem that it is not possible to respond to a wide range of load changes.

In order to cope with large load changes in conventional fluidized bed boilers, it is necessary to change the bed height of the fluidized bed, divide the fluidized bed into multiple horizontal cells, and perform partial operation of the fluidized bed. The layer temperature is maintained by reducing the substantial intralayer heat transfer area under load. However, in order to change the bed height of the fluidized bed, it is necessary to install a large-scale level adjustment device, and there are also disadvantages in that rapid load changes are difficult. In addition, partial operation by layer division is
In particular, it takes time to restart the stopped layer when the load increases, and there are disadvantages in that the load followability is poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of operating a fluidized bed combustion apparatus that eliminates the drawbacks of the above-mentioned prior art and enables a large change in load with a relatively simple apparatus.

The present invention provides a method for operating a combustion device having heat transfer tubes in a fluidized bed and a plurality of stages of air distribution devices in the vertical direction of the fluidized bed, in which an air introduction valve is provided in the air distribution device of the combustion device. , the air supply level in the vertical direction of the air distribution device is changed according to the load.

The present invention provides the same function as bed height change or horizontal partial operation by performing partial operation in the vertical direction of the fluidized bed as described above, changes the substantial heat transfer area of the heat transfer tubes in the bed, and significantly This enables easy load changes.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a sectional view of a main part of a fluidized bed boiler showing an embodiment of the present invention, and FIG. 2 is a plan view taken along line - in FIG. 1. In the figure, a fluidized bed boiler main body 1 contains a fluidized medium so that a fluidized bed 2 is formed by introduced air, heat exchanger tubes 3 are arranged in the fluidized bed 2, and further between the heat exchanger tubes 3. Air distribution pipe (pipe grid) 4 in the vertical direction
A, 4B and 4C are each provided horizontally. A large number of air distribution tubes 4A, 4B, and 4C are provided in parallel as shown in FIG. 2, and one end of each distribution tube is closed, while the other end is connected to a common header 5A, 5B, and 5C, respectively. Further, the header is connected to an air supply pipe 7 via valves 6A, 6B, and 6C. Air distribution tube 4
At the bottom of each of A, 4B and 4C, air blowing holes 10 are provided linearly at predetermined intervals. On the other hand, a fuel supply pipe 8 is provided on the side wall of the main body above the fluidized bed. The lower part of the main body has an inverted conical shape, and the lower end thereof is provided with a discharge hole and a valve 9 for taking out a fluid medium or coarse particles such as fuel particles as necessary.

In the above configuration, when the load on the fluidized bed boiler is small, the valves 6A and 6B are closed and the valve 6C is opened to supply air only to the uppermost air distribution pipe 4C,
The fuel in the fluidized bed above the air dispersion tube is combusted. As the boiler load increases, the valves 6B and 6 of the second and third stage air distribution pipes 4B and 4A are
A is opened to increase the combustion zone of the fluidized bed. Combustion gas is carried from above the fluidized bed to a flue (not shown) as shown by the arrow. In this way, the combustion zone of the fluidized bed can be increased or decreased in response to a wide range of boiler loads, and operation can be performed in accordance with the required load.

In the above embodiment, since the air dispersion tubes are arranged horizontally like the heat transfer tubes, the structure is simple and the design is easy. Note that when the heat exchanger tubes are arranged vertically, steam collapse occurs at the bent portion of the upper part, but when the heat exchanger tubes are arranged horizontally as in this embodiment, such a problem does not occur. In addition, in the present invention, the number of installation stages of the air dispersion tubes 4A to 4C may be other than three stages as in the embodiment, and may be two stages or a multistage number of four or more stages as necessary. In addition to the fluidized bed boiler, the present invention can be similarly applied to a heat recovery type general fluidized bed furnace in which heat transfer tubes are arranged in the bed.

As described above, according to the present invention, a wide load range can be accommodated by providing multiple stages of air dispersion tubes in parallel with the heat transfer tubes arranged laterally within the fluidized bed and changing the air supply level within the fluidized bed. The device can be operated easily and has a simple structure.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a fluidized bed boiler showing an embodiment of the present invention, and FIG. 2 is a plan sectional view taken along the line - in the direction of arrows. 1... Fluidized bed boiler main body, 2... Fluidized bed, 3... Heat exchanger tube, 4A, 4B, 4C... Air dispersion tube, 5A, 5
B, 5C...header, 6A, 6B, 6C...valve, 7...
Air supply pipe.

Claims (1)

[Claims] 1. In a method of operating a combustion device having a heat transfer tube in a fluidized bed and a plurality of stages of air distribution devices in the vertical direction of the fluidized bed, an air introduction valve is provided in the air distribution device of the combustion device, A method for operating a fluidized bed combustion apparatus, characterized in that the level of air introduced in the vertical direction of the air dispersion apparatus is changed accordingly.