JPS6113528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fluidized bed combustion apparatus suitable for reducing the amount of nitrogen oxides (hereinafter referred to as _NOx ) generated.

[Background of the invention]

In conventional fluidized bed combustion, combustion air is introduced into the fluidized bed only through the distribution plate at the bottom of the fluidized bed. In other words, the first example shows a conventional fluidized bed combustion apparatus.
In the figure, fuel is supplied to a fluidized bed 6 in a fluidized bed combustion vessel 1 through a fuel supply pipe 4, and combustion air is supplied to a dispersion plate 5 at the bottom of the fluidized bed 6 through a combustion air introduction pipe 2. The combustion exhaust gas is introduced into the fluidized bed 6 through the hollow cylinder 7 and flows out from the exhaust gas outlet pipe 3.

In this case, the oxygen content in the fluidized bed 6 is
It is large in the lower part of the fluidized bed 6 and decreases toward the upper part of the fluidized bed 6. Therefore, since combustion is carried out in a strongly oxidizing atmosphere in the lower part of the fluidized bed 6, there is a drawback that a large amount of NO _x is generated, which has been a problem in the past.

[Purpose of the invention]

Except for the above-mentioned drawbacks, the present invention can be used in fluidized bed combustion without compromising combustion performance or other advantages.
The object of the present invention is to provide a NO _x reduction combustion device that can reduce the amount of NO _x generated.

[Summary of the invention]

This invention provides a fluidized bed combustion vessel with at least three combustion air inlets, the first of which is a dispersion plate disposed at the bottom of the fluidized bed as a dispersion means, and the second inlet is a dispersion plate disposed at the bottom of the fluidized bed. an opening in the layer, and a third
The inlet is opened in the hollow cylinder.

The at least three combustion air inlets each communicate with at least three branch pipes branched from one combustion air introduction pipe, and each of the at least three branch pipes has a combustion air inlet. It is characterized by being equipped with a quantity control valve.

[Embodiments of the invention]

Embodiments of the present invention will be explained based on the drawings. FIG. 2 is a diagram showing the NO _x reduction combustion apparatus in a fluidized bed according to the present invention, and the same numbers are used for the same parts as those in FIG. 1 already explained.

In Figure 2, from the combustion air introduction pipe to the branch pipe 1
4, 15, and 16 are branched. And branch pipe 1
4 is a first inlet port located at the bottom of the fluidized bed 6, and a branch pipe 1 is connected to a dispersion plate 5 as a dispersion means.
5 and 16 are second inlet ports 11 and 12 that open into the fluidized bed 6, and a branch pipe 17 is a third inlet port 13 that opens into the hollow cylinder 7. They communicate with each other. In addition, the branch pipe 14,
15, 16, and 17 have air flow control valves 24,
25, 26, and 27 are provided.

With this structure, fuel is supplied from the fuel supply pipe 4 into the fluidized bed 6, and the combustion air introduced from the combustion air introduction pipe 2 is controlled in flow rate by the air flow control valves 24 to 27. The branch pipe 14 is adjusted
It is divided into ~17. Branch pipe 14 whose flow rate is adjusted
The combustion air divided into 1 to 17 flows from the distribution plate 5 to the bottom of the fluidized bed 6, bypasses the distribution plate 5 and enters the inside of the fluidized bed 6 from the inlet ports 11 and 12, and then passes through the distribution plate 5 to the bottom of the fluidized bed 6. Bypass 5 and inlet 1
3 into the hollow cylinder part 7 in multiple stages. The amount of air introduced from the combustion air introduction pipe 2 is the amount necessary to flow the fluidized medium in the fluidized bed 6 and to burn the fuel supplied into the fluidized bed 6 by the fuel supply pipe 4. It is the amount of air.

Therefore, combustion in a strongly oxidizing atmosphere due to the presence of combustion air, which is an oxygen-containing gas, concentrated in the lower part of the fluidized bed 6, as in conventional fluidized bed combustion, is prevented, and the oxygen-containing gas is Combustion air exists dispersedly within the fluidized bed 6 and the cavity 7, and the fuel within the fluidized bed 6 burns in an atmosphere with a relatively low oxygen content, that is, a reducing atmosphere. , the amount of NO _x generated is reduced.

In this case, the distribution plate 5 is bypassed and the inlet port 11 is
The temperature at which the fuel burns near the surface of the fluidized bed 6 hardly rises due to the second stage combustion air sent into the fluidized bed 6 from the fluidized bed 6 due to the large heat capacity of the fluidized bed 6. It uses ideal two-stage combustion, reducing the amount of NO _x generated. That is,
The entire fluidized bed 6 performs low NO _x combustion due to low oxygen concentration combustion and low temperature combustion.

Then, the unburned portion containing CO generated by the low _NOx combustion in the fluidized bed 6 is stored in the hollow cylinder 7.
Combustion is carried out by the combustion air introduced from the inlet 13, and the amount of CO in the combustion exhaust gas, which is one of the indicators of combustion efficiency, is reasonably reduced.

〔Effect of the invention〕

As explained above, in this invention, combustion air is divided and fed into the bottom of the fluidized bed, the inside of the fluidized bed, and the hollow cylinder in multiple stages. Therefore, since the heat capacity of the fluidized bed is large, the temperature hardly rises during the second stage combustion, making it possible to perform ideal two stage combustion. That is, since the entire fluidized bed performs low NO _x combustion due to low oxygen concentration combustion and low temperature combustion, there is an effect that the amount of NO _x generated can be reduced.

In addition, low _NOx combustion in the fluidized bed generates
Since the unburned portion containing CO is finally combusted in the cavity, it is possible to reasonably reduce the amount of CO in the combustion exhaust gas.

[Brief explanation of the drawing]

Figure 1 shows a conventional fluidized bed combustion apparatus, Figure 2
The figure is a diagram showing a _NOx reduction combustion device in a fluidized bed according to the present invention. 1...Fluidized bed combustion vessel, 2...Combustion air introduction pipe,
3...Exhaust gas outflow pipe, 4...Fuel supply pipe, 5...Dispersion plate, 6...Fluidized bed, 7...Cavity part, 11, 12, 13
...Inlet port, 14, 15, 16, 17... Branch pipe, 2
4, 25, 26, 27...Air flow control valve.

Claims (1)

[Claims] 1. A fluidized bed combustion vessel is provided with at least three combustion oxygen-containing gas inlets, the first of which is a dispersion means disposed at the bottom of the fluidized bed, and the second inlet is a dispersion means disposed at the bottom of the fluidized bed. A combustion device for reducing nitrogen oxides in a fluidized bed, characterized in that the third inlet is opened into the fluidized bed, and the third inlet is opened into the hollow cylinder. 2. The at least three combustion oxygen-containing gas inlet ports each communicate with at least three branch pipes branched from one combustion oxygen-containing gas introduction pipe, and each of the branch pipes is provided with an oxygen-containing gas flow rate regulating valve. A nitrogen oxide reduction combustion apparatus in a fluidized bed according to claim 1, characterized in that the combustion apparatus is equipped with: