JPH08247423A - Dual-flow type garbage incinerator - Google Patents

Abstract

PURPOSE: To restrain generation of poisonous gas, such as CO, NOx and the like, by a method wherein the combustion efficiency of substances to be incinerated in the combustion chamber of a garbage incinerator is increased to burn unburnt gas completely and reduce the generating amount of poisonous gas, such as CO, NOx and the like, and decompose thermally dioxines in exhaust gas. CONSTITUTION: A wedge type intermediate ceiling 11, constituted of an upper wall 12, forming a gas flow passage 8 for guiding the exhaust gas of combustion into a gas mixing chamber 6 and slanted by a predetermined angle, and a lower wall 13, slanted toward the fire gratings 3 of the bottom part of a combustion chamber by a predetermined angle, is provided near the opening unit 6a of a flue in the combustion chamber 1 of a garbage incinerator. Unburnt gas and exhaust gas of combustion, which contains much amount of oxygen, are mixed in a gas mixing chamber 6 after passing through the gas flow passage 8 formed of the intermediate ceiling 11 whereby unburnt gas is burnt completely to reduce the amount of CO and NOx in exhaust gas while the generation of dioxines is restrained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-flow type refuse incinerator for incinerating municipal waste, sewage sludge, combustible industrial waste and the like.

[0002]

2. Description of the Related Art Combustion exhaust gas generated from a refuse incinerator for incinerating municipal solid waste, sewage sludge, combustible industrial waste, and the like is unburned gas containing a large amount of carbon monoxide, aromatic hydrocarbons, and the like. It contains organic chlorine compounds such as dioxins, which are extremely toxic.

Therefore, many studies have been conducted in the past regarding methods for suppressing the generation of these harmful substances.
For example, JP-A-2-166306 discloses that in an incinerator,
A double-flow type in which a combustion exhaust gas containing a large amount of unburned gas and a combustion exhaust gas containing a large amount of oxygen are provided separately and the two are mixed in the flow passage to completely burn the unburned gas A method (hereinafter referred to as the prior art) for suppressing the generation of dioxins in exhaust gas by using a refuse incinerator and thermally decomposing them is disclosed.

FIG. 7 is a schematic vertical sectional view of a conventional double-flow type refuse incinerator. As shown in the drawing, an inlet 2 for the material to be incinerated is provided at the upper end on one end side of the combustion chamber 1, and a large amount of combustion exhaust gas and unburned gas is contained on the upper end at the other end of the combustion chamber 1. A gas mixing chamber 6 for mixing with the gas to be connected is connected. The bottom of the combustion chamber 1 is provided with a stepped grate 3 that is inclined downward from the charging port 2 side. Below the grate 3, a supply for supplying combustion air is provided. A hollow block 5 connected to the pipe 4 is provided.

At the central portion of the combustion chamber 1 including the combustion starting point,
At the upper part of the gas mixing chamber 6 near the opening 6a, the opening 6a is formed.
An intermediate ceiling 7 made of a refractory material or a wall structure of a water cooling wall of a boiler, which is inclined downward at a predetermined distance from, is arranged. The intermediate ceiling 7 forms a gas flow path 8 that guides the combustion exhaust gas to the gas mixing chamber 6 between itself and the furnace wall, and provides radiant heat due to heat reflection to the incineration object on the grate 3. There is.

In the double-flow type refuse incinerator having the above-mentioned structure, the substance to be incinerated supplied from the charging port 2 into the combustion chamber 1 is
It is dried and burned while moving down the grate 3. At this time, the amount of combustion air supplied into the combustion chamber 1 through the air supply pipe 4 on the upstream side of the grate close to the charging port 2 and the cavity block 5 is set to the same as the air supply pipe 4 on the downstream side of the grate. By reducing the amount of combustion air supplied through the cavity block 5, the upstream side grate 3
Generate a large amount of unburned gas from the incinerated materials. The unburned gas thus generated is guided from the upper end side of the intermediate ceiling 7 into the gas flow path 8 formed between the intermediate ceiling 7 and the furnace wall, as shown by an arrow 9.

On the other hand, the combustion exhaust gas containing a large amount of oxygen, which is completely burned by the combustion air supplied into the combustion chamber 1 through the air supply pipe 4 and the cavity block 5 on the downstream side of the grate, is shown by an arrow 10. Thus, the gas is introduced from the lower end side of the intermediate ceiling 7 into the gas flow path 8 ′, mixed with the unburned gas in the gas mixing chamber 6 and burned in two stages. As a result, the unburned gas is completely combusted and the dioxins in the exhaust gas are thermally decomposed and their generation is suppressed.

[0008]

In the above-mentioned double-flow type refuse incinerator, the inclination angle of the intermediate ceiling 7 arranged in the combustion chamber 1 is determined by the combustion efficiency of the incineration object and the combustion exhaust gas in the combustion chamber 1. It is an important factor for two-stage combustion.
That is, when the inclination angle α of the intermediate ceiling 7 is small, the ash generated by the combustion of the incineration material is accumulated on the upper surface of the intermediate ceiling 7, and the gas flow passage 8 is narrowed or blocked, resulting in good combustion. You will not be able to continue.

On the other hand, if the inclination angle α of the intermediate ceiling 7 is too large, the unburned gas generated from the incineration material on the upstream side of the grate 3 burns before flowing into the gas flow passage 8, and the gas mixing chamber 6 As a result of insufficient second-stage combustion in the interior, the thermal decomposition of dioxins in the exhaust gas becomes insufficient, and the generation thereof cannot be suppressed. Further, the space H for maintaining a good flow of the combustion exhaust gas is required between the lower end of the intermediate ceiling 7 and the grate 3, and the volume of the combustion chamber 1 becomes excessive. And the inflammability of the material to be incinerated deteriorates.

Conventionally, the inclination angle, size, position and the like of the intermediate ceiling 7 have been empirically determined from the above-mentioned viewpoint. Therefore, depending on the operating conditions, the above-mentioned problems occur, and it is not possible to reduce the harmful gases such as CO and NOx generated by combustion, and the unburned amount in exhaust ash, that is, the heat shield reduction amount to the target value. It was Also, due to excessive rise in the temperature of combustion exhaust gas, the furnace wall refractory in the combustion chamber and the grate support metal are likely to be damaged. Growing up
There were problems such as overhanging in the furnace.

Therefore, an object of the present invention is to solve the above-mentioned problems, improve the combustion efficiency of the incineration object in the combustion chamber, and completely burn the unburned gas to generate the harmful gas such as CO and NOx. It is intended to provide a double-flow type refuse incinerator capable of reducing the amount of dioxin and thermally decomposing dioxins in exhaust gas and suppressing the generation thereof.

[0012]

According to the present invention, there is provided an inlet for an incineration object at an upper part on one end side, and a mixing chamber for combusted exhaust gas and a gas containing a large amount of unburned gas is connected to an upper part on the other end side. Also, in the combustion chamber of the refuse incinerator in which a grate is provided at the bottom thereof, in the vicinity of the opening of the gas mixing chamber, an intermediate ceiling inclined downward at a predetermined interval from the opening is arranged, Combustion exhaust gas containing a large amount of unburned gas generated on the upstream side of the grate through a gas flow path formed between the middle ceiling and the upper furnace wall of the combustion chamber, and the combustion by the middle ceiling. Through a gas passage formed between the lower furnace wall of the chamber and the combustion exhaust gas containing a large amount of oxygen generated on the downstream side of the grate in the gas mixing chamber to completely remove the unburned gas. Odor in a double-flow type waste incinerator that burns An upper wall inclined at a predetermined angle, the intermediate ceiling forming the gas flow path for guiding the combustion exhaust gas to the gas mixing chamber, and a lower portion inclined at a predetermined angle toward a grate at the bottom of the combustion chamber It is characterized in that it is formed in a wedge shape including a wall.

[0013]

According to the incinerator of the present invention, the intermediate ceiling is directed to the upper wall forming the gas flow path for guiding the combustion exhaust gas to the gas mixing chamber, and the grate that gives radiant heat due to heat reflection to the incineration object. And the lower wall, the upper wall and the lower wall are inclined at a specific angle. This inclination angle is a specific range, that is, the inclination angle of the upper wall
By setting the inclination angle of the lower wall to be 47 ° or more and within the range of 15 to 45 °, ash does not accumulate on the upper surface of the upper wall surface, and the gas flow passage is not narrowed or blocked, and, Due to the heat reflection by the lower wall, radiant heat can be efficiently given to the incineration object on the grate, and the combustion chamber is kept in an appropriate volume. Therefore, the combustion exhaust gas can be completely combusted without lowering the furnace temperature and the combustibility, and the amount of CO and NOx in the combustion exhaust gas and the reduction of heat scavenging in the exhaust ash can be appropriately reduced. Be seen.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the device of the present invention will be described with reference to the drawings. FIG. 1 is a schematic vertical sectional view showing an embodiment of the device of the present invention. As shown in the drawing, an input port 2 for the material to be incinerated is provided in the upper part on one end side of the combustion chamber 1.
A gas mixing chamber 6 for mixing the combustion exhaust gas and a gas containing a large amount of unburned gas is connected to the upper part on the other end side of
The bottom of the combustion chamber 1 is provided with a stepped grate 3 inclined downward from the charging port 2 side, and below the grate 3, a supply pipe for supplying combustion air. The provision of the cavity block 5 connected to the 4 is similar to that of the conventional incinerator.

At the central portion including the combustion starting point in the combustion chamber 1,
At the upper part of the gas mixing chamber 6 near the opening 6a, the opening 6a is formed.
An intermediate ceiling 11 which is inclined downward at a predetermined interval from is disposed, and the intermediate ceiling 11 forms gas flow paths 8 and 8 ′ for guiding the combustion exhaust gas to the gas mixing chamber 6 between the intermediate ceiling 11 and the furnace wall. ing.

The intermediate ceiling 11 according to the present invention is inclined at a predetermined angle between itself and the furnace wall to form the gas passages 8 and 8'which guide the combustion exhaust gas to the gas mixing chamber 6 and serve as a retention space for the combustion exhaust gas. The upper walls 12 and 13 and the lower wall 14 inclined at a predetermined angle for giving radiant heat by heat reflection to the material to be incinerated on the grate 3 have a hollow wedge shape having a cavity 15 inside. The upper walls 12 and 13 and the lower wall 14 are made of refractory material or boiler water-cooling walls.The cavity 15 contains reinforcements for the upper walls 12 and 13 and the lower wall 14, air pipes for injecting into the furnace, etc. Can be placed.

The inclination angle α of the upper walls 12 and 13 of the intermediate ceiling 11
Is preferably 47 ° or more. 2 shows the upper wall 12
3 is a graph showing the relationship between the inclination angle α and the amount of ash deposited.
As is apparent from FIG. 2, the inclination angle α of the upper walls 12 and 13 is
If it is less than 47 °, the ash generated by the combustion of the incineration material is accumulated on the upper surfaces of the upper walls 12 and 13, and the gas passage 8 is narrowed, or the gas passage 8 is blocked, so that good combustion is achieved. Will not be able to continue. The upper limit of the inclination angle α of the upper walls 12 and 13 is preferably 55 °. Inclination angle α is 55
Beyond °, formed between the intermediate ceiling 11 and the furnace wall,
The interval A forming the flow path of the upstream side combustion exhaust gas becomes too narrow, which causes a problem that the flow of the combustion exhaust gas to the gas flow path 8 deteriorates.

The inclination angle β of the lower wall 14 of the intermediate ceiling 11 is 15
It is preferably within the range of to 45 °. Figure 3 shows the lower wall
14 is a graph showing the relationship between the inclination angle β of 14 and the CO amount in the combustion exhaust gas, FIG. 4 is a graph showing the relationship between the inclination angle β of the lower wall 14 and the NOx amount in the combustion exhaust gas, and FIG. 6 is a graph showing the relationship between the inclination angle β of the lower wall 14 and the heat shield weight loss. As shown in FIGS. 3 to 5, when the inclination angle β of the lower wall 14 is less than 15 °, the volume of the combustion chamber 1 becomes too small and the combustion exhaust gas cannot be completely combusted. The reduction of the amount of NOx and NOx, and the reduction of the amount of heat shield are insufficient.

On the other hand, when the inclination angle β of the lower wall 14 exceeds 45 °, the unburned gas generated from the incineration material of the upstream grate 3 burns before flowing into the gas flow path 8 to mix the gas. As a result of the insufficient two-stage combustion in the chamber 6, the amount of CO and NOx in the combustion exhaust gas and the reduction of the heat shield loss become insufficient, and the radiant heat from the lower wall 14 of the intermediate ceiling 11 decreases. As a result of insufficient heating in the dry stage grate, the weight loss in ash increases.

The amount of CO in the combustion exhaust gas is an index showing the combustion state and also an index showing the amount of dioxins generated. FIG. 6 is a graph showing the relationship between the amount of CO in combustion exhaust gas and the generation concentration of dioxins. As is clear from FIG. 6, when the amount of CO in the combustion exhaust gas exceeds 3 ppm, the concentration of dioxins sharply increases.

As described above, the inclination angle β of the lower wall 14 of the intermediate ceiling 11 secures an appropriate gas combustion space in the combustion chamber 1 and supplies radiant heat by heat reflection to the incineration object on the grate. And unburned exhaust gas and combustion exhaust gas,
The openings for leading to the gas flow paths 8 and 8'from the front and rear of the intermediate ceiling 11 are secured, and these are important elements for reducing the amount of CO and NOx in the combustion exhaust gas, and the reduction of heat shield. is there.

As described above, the intermediate ceiling 11 has the upper walls 12 and 13 having the inclination angle α of 47 ° or more and the inclination angle β of 15 to 45 °.
By forming it into a wedge shape having a cavity 15 inside, which is composed of the lower wall 14 of the above, the ash generated by the combustion of the incineration material does not deposit on the upper surface of the intermediate ceiling 11, and inside the gas path of the gas mixing chamber 6. The two-stage combustion in the above is sufficiently performed, and the combustibility of the incineration object is improved.

Further, the intermediate ceiling 11 can effectively stir the in-reactor gas even in the vicinity of the core by blowing the secondary air into the furnace by passing the air piping through the cavity 15 and mixing the gas. Complete combustion of unburned gas in chamber 6 is possible. As a result, the amount of CO and NOx in the combustion exhaust gas and the amount of heat scavenging are sufficiently reduced, the thermal decomposition of dioxins is promoted, their generation is appropriately suppressed, and good combustion can be continued. it can.

Further, since good combustion as described above can be performed, it is possible to perform combustion with a lower excess air ratio, so that the equipment of the air-exhaust gas system of the plant can be downsized and energy can be saved. At the same time, it becomes possible to recover a large amount of steam and electric power from the exhaust gas. In addition, good combustion prevents clinker from adhering, does not damage the grate support hardware, etc., and extends the life of the combustion chamber furnace wall refractory, and reduces incinerator maintenance. To be done.

[0025]

As described above, according to the present invention,
The combustion efficiency of the incineration object in the combustion chamber is increased, and the CO and NOx amounts in the combustion exhaust gas and the heat shield reduction amount are sufficiently reduced, and the thermal decomposition of dioxins is promoted, and its generation is properly performed. And the like, and industrially useful effects can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the device of the present invention.

FIG. 2 is a graph showing the relationship between the inclination angle of the upper wall and the amount of ash deposited.

FIG. 3 is a graph showing the relationship between the inclination angle of the lower wall and the amount of CO in the combustion exhaust gas.

FIG. 4 is a graph showing the relationship between the inclination angle of the lower wall and the NOx amount in the combustion exhaust gas.

FIG. 5 is a graph showing the relationship between the inclination angle of the lower wall 13 and the amount of heat shield loss.

FIG. 6 is a graph showing the relationship between the amount of CO in combustion exhaust gas and the generation concentration of dioxins.

FIG. 7 is a schematic vertical sectional view of a conventional double-flow type refuse incinerator.

[Explanation of symbols]

 1 Combustion Chamber 2 Input Port 3 Grate 4 Air Supply Pipe 5 Cavity Block 6 Gas Mixing Chamber 6a Opening 7 Intermediate Ceiling 8 and 8'Gas Flow Path 9 Arrow 10 Arrow 11 Intermediate Ceiling 12 Upper Wall 13 Upper Wall 14 Lower Wall 15 cavity

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F23C 11/00 322 F23C 11/00 322 F23M 5/06 ZAB F23M 5/06 ZAB (72) Inventor Shigeyuki Doi, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd. (72) Inventor Takashi Ishiuchi 5335-5 Ohba, Fujisawa City, Kanagawa Prefecture

Claims (3)

[Claims] 1. An inlet for an incineration object is provided at an upper part of one end side,
An opening of the gas mixing chamber in the combustion chamber of the refuse incinerator in which the mixing chamber of the combustion exhaust gas and the gas containing a large amount of unburned gas is connected to the upper part of the other end side and the grate is provided in the bottom part thereof In the vicinity, an intermediate ceiling that is inclined downward with a predetermined distance from the opening is disposed, and through the gas flow path formed between the intermediate ceiling and the upper furnace wall of the combustion chamber, the grate of the grate is formed. Combustion exhaust gas containing a large amount of unburned gas generated on the upstream side, through the gas passage formed between the lower furnace wall of the combustion chamber by the intermediate ceiling, oxygen generated on the downstream side of the grate Combustion exhaust gas containing a large amount, in the gas mixing chamber, in the double-flow type refuse incinerator to completely burn the unburned gas, the intermediate ceiling, the gas to guide the combustion exhaust gas to the gas mixing chamber Forming a flow path An upper wall which is inclined at a predetermined angle,
A double-flow type refuse incinerator, which is formed in a wedge shape including a lower wall that is inclined at a predetermined angle toward the grate at the bottom of the combustion chamber. 2. The inclination angle of the upper wall of the intermediate ceiling is
Is 47 ° or more, and the inclination angle of the lower wall is 15 to
The double-flow type refuse incinerator according to claim 1, which is in a range of 45 °. 3. The double-flow-type refuse incinerator according to claim 1, wherein the wedge-shaped intermediate ceiling is hollow inside.