JPS62182516A - Burning method for fluidized bed type incinerator - Google Patents

Abstract

PURPOSE:To achieve stable burning by controlling burning in such a way that a part of exhaust gas discharged from a freeboard part is introduced into the freeboard part and a fluidized layer part or either one of the two. CONSTITUTION:A part of exhaust gas which is discharged from a freeboard part 7 and cooled by an exhaust gas cooling device 10 and in which dust etc. is treated by an exhaust gas treating device 11 is supplied into one or both of the part 7 and a fluidized layer part 3 the two through an exhaust gas return pipe 16. Since exhaust gas together with primary air is supplied from air distributing pipes into the part 3, oxygen concentration in the primary air is reduced and since gas amount in the fluidized layer is increased, the temp. in the part 3 is reduced and drying, thermal cracking, and burning are carried out gently to stabilize burning. Since flame temp. at the part 7 is controlled by exhaust gas, the temp. at the part 3 is indirectly controlled to promote the stabilization of burning at the part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a combustion method in a fluidized bed incinerator, and particularly to a method for recirculating exhaust gas to achieve stable combustion.

[Prior Art] A fluidized bed incinerator uses a jet of air (also referred to as secondary air) that is blown out above an aeration device installed almost horizontally in the lower part of the furnace to transport the materials to be incinerated into a fluidized medium. A fluidized bed section is formed that is fluidized and combusted together with the barrel sand, and a freeboard section is formed above this fluidized bed section that completely burns the combustible gas generated from the fluidized bed section. Combustion air (also referred to as secondary air) was supplied to the freeboard section, and all the exhaust gas exhausted from the freeboard section was treated and released into the atmosphere through the chimney. - A packed bed filled with combustion residue is formed below the air diffuser, and the residue is cut out from the bottom of the bed by a screw.

[Problems to be solved by the invention] By the way, the properties of the material to be incinerated (calorific value,
Since the moisture content, size of lumps, etc.) changed from moment to moment, rotation was needed to keep the combustion state constant. In order to achieve stable combustion, it is sufficient to control the supply amount of primary and secondary air, but since the combustion state changes instantaneously, it is necessary to control the air supply amount by rotation to achieve stable combustion. was difficult.

In particular, when the temperature of the fluidized bed section increased, the drying, thermal decomposition and combustion of waste tended to become more intense.

Therefore, as a result of intensive research to solve the problems of the above-mentioned conventional technology, it was found that if the temperature of the fluidized bed section is earth-like, the drying of the incinerated material
It was discovered that thermal decomposition and combustion tend to become more intense, and this led to the completion of the present invention. An object of the present invention is to provide a combustion method for a fluidized bed incinerator that can achieve stable combustion.

[Means for Solving the Problems] The present invention provides a fluidized bed incinerator in which a freeboard section is formed above the fluidized bed section, in which part of the exhaust gas exhausted from the freeboard section is transferred to the freeboard section and the above-mentioned freeboard section. The fluidized bed section or both are introduced into one side to control combustion.

[Example] An example of the present invention will be described below based on the accompanying drawings.

As shown in the figure, a fluidized bed incinerator 1 has a plurality of air diffuser pipes 2 arranged horizontally in the lower part of the furnace, and a fluidized bed section 3 above the air diffuser pipes 2.
In addition, a filled layer portion 4 is formed below. A primary air supply pipe 6 with a primary blower 5 interposed therein is connected to the diffuser pipe 2 .

A freeboard section 7 is formed above the fluidized bed section 3, and an exhaust gas pipe 9 for sending exhaust gas to a chimney 8 is connected to the top of the furnace, and an exhaust gas cooling equipment 10. Exhaust gas treatment equipment (dust collector, etc.) 11 and induced blower 12 are provided in this order. A secondary air supply pipe 14 with a secondary air blower 13 interposed therebetween is connected to the freeboard section 7, and an incineration material inlet 15 is formed therein.

In order to carry out the method of the present invention, an exhaust gas return pipe 16 branched from the downstream side of the induced blower 12 in the exhaust gas pipe 9 is connected to the freeboard section 7, and an exhaust gas recirculation fan 17 is connected to the exhaust gas return pipe 16. is interposed. Further, in order to supply exhaust gas to the diffuser pipe 2, a branch pipe 18 branched to the F flow of the exhaust gas recirculation fan 17 in the exhaust gas return pipe 16 is connected upstream of the primary blower 5 in the primary air supply pipe 6. , this branch pipe 18 has a valve 1
9 is interposed.

In the above configuration, the exhaust gas is exhausted from the freeboard section 7 and cooled by the exhaust gas cooling equipment 10 (usually 300
℃ or below), and a part of the exhaust gas that has been treated by dust collection etc. by the exhaust gas treatment equipment 11 is supplied to either or both of the freeboard section 7 and the fluidized bed section 3 via the exhaust gas return pipe 9. The exhaust gas flows into the fluidized bed section 3 together with the primary air through the air diffuser pipe 2.
- The oxygen concentration in the air is lowered, and the amount of gas in the fluidized bed section is increased, so the humidity in the fluidized bed section 3 is reduced and the materials to be incinerated are dried.

Thermal decomposition and combustion become slower and combustion becomes more stable.

Further, since the flame temperature in the freeboard section 7 is suppressed by the exhaust gas, the temperature of the fluidized bed section 3 is indirectly suppressed, which helps stabilize combustion in the fluidized bed section 3. Furthermore, nitrogen oxides can be reduced by supplying exhaust gas.

In addition to the illustrated example, the method of supplying the exhaust gas to the freeboard section 7 may include a method of mixing it with secondary air and supplying it. Further, as a method for supplying the exhaust gas to the fluidized bed section 3, in addition to the illustrated example, a method of supplying the exhaust gas separately from the gas may be adopted.

Furthermore, the temperature of the fluidized bed section 3 may be detected to control the amount of exhaust gas supplied.

[Effects of the Invention] In summary, the present invention exhibits the following excellent effects.

(1) Since a part of the exhaust gas is introduced into the fluidized bed section and/or the freeboard section, combustion in the fluidized bed section is slowed down and the temperature of the fluidized bed section is suppressed, thereby reducing the amount of material to be incinerated in the fluidized bed section. drying, thermal decomposition and combustion can be performed slowly and stably.

(2) This makes it possible to prevent the generation of unburned gas and also to reduce nitrogen oxides.

[Brief explanation of drawings]

The figure is a configuration diagram showing the piping configuration of a fluidized bed incinerator for carrying out the method of the present invention. In the figure, 1 is a fluidized bed incinerator, 2 is an aeration pipe, 3 is a fluidized bed section, 7 is a freeboard section, 9 is an exhaust gas pipe, and 16 is an exhaust gas return pipe.

Claims (1)

[Claims] In a fluidized bed incinerator in which a freeboard section is formed above the fluidized bed section, a part of the exhaust gas exhausted from the freeboard section is introduced into the freeboard section and/or the fluidized bed section for combustion. A combustion method in a fluidized bed incinerator, characterized in that the combustion method is controlled.