JPH05126326A - Combustion furnace - Google Patents

Abstract

PURPOSE:To minimize the non-ignited gas by a method wherein an combustion furnace is comprised of a passage at an adjusting part, a lower combustion part, an upper combustion part, the first barrier wall and the second barrier wall. CONSTITUTION:Secondary air is blown from a secondary air injection hole 16a of the first barrier wall 16 into a lower combustion chamber 13 so as to mix the secondary air with non-ignited gas. In addition, gas (partially including non-ignited gas) of which combustion is completed in the lower combustion chamber 13 is divided into substantially equal volume, passes through a passage between a furnace wall 11 and the first barrier wall 16, strikes against a passage 14 of an adjusting part and merged from each other. Gas of which speed is increased at the passage 14 at the adjusting part flows into an upper combustion chamber 15 having a wide cross sectional area. The second barrier wall 17 is arranged near an outlet port of the passage 14 at the adjusting part, where the gas is divided into substantial equal volume, passes through the passage between the furnace wall 11 and the second barrier wall 17 and merges again at the upper combustion chamber 15. Combustion gas substantially completely mixed is stayed at the upper combustion chamber 15 for a predetermined time while keeping its high temperature and then discharged. With such an arrangement, it is possible to restrict the non-ignited gas :, to its minimum value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incinerator for municipal waste and the like, which can suppress unburned gas generated during combustion of incinerator to a minimum.

[0002]

2. Description of the Related Art Conventionally, various techniques have been proposed for suppressing unburned gas in this type of incinerator.
For example, "Garbage incineration method and apparatus therefor" disclosed in Japanese Patent Publication No. 63-228414 and "NOx and unburned gas control in fluidized bed incinerator" disclosed in Japanese Patent Publication No. 63-279013. There is a device.

In any of the above techniques, a secondary air blowing device is arranged across the combustion chamber, and the vortex flow generated by the blowing air promotes the mixing of oxygen and unburned gas to suppress harmful substances.

[0004]

However, in any of the above, the mixing of the secondary air and the unburned gas depends on the penetrating force of the ejected air (blowing velocity of the secondary air), and the secondary air ejection hole Since the agitation force abruptly weakens as the distance increases, the unburned gas may slip through the region where the influence of the secondary air ejection does not reach and the unburned gas and air may not be mixed. Further, if the number of air ejection holes is increased in order to prevent this, there arises a problem that the penetrating force of ejected air is weakened.

Further, even if a throttle portion is provided in the latter stage as in the device disclosed in Japanese Patent Laid-Open No. 3-282414, unburned gas that has passed through without contact with air will pass through the throttle portion as it is. There was also a problem.

The present invention has been made in view of the above points, and the unburned gas does not pass through the unreacted gas, and the reaction between the unburned gas and oxygen progresses reliably and rapidly. It is an object of the present invention to provide an incinerator that can minimize the waste.

[0007]

In order to solve the above-mentioned problems, the present invention burns incinerators in a grate part or a fluidized sand layer part and introduces the generated combustion gas into a combustion chamber connected to the upper part of the combustion gas. In an incinerator configured to mix with secondary air in the chamber to maintain a fixed residence time and complete combustion, the middle of the combustion chamber is narrowed in the cross-sectional direction with respect to the gas flow direction and extended for a predetermined distance A throttle passage that speeds up the gas passage velocity, a lower combustion chamber that is defined by a part of the combustion chamber and is below the throttle passage, and a laterally enlarged lower combustion chamber that is defined by a part of the combustion chamber and is above the throttle passage. An upper combustion chamber that is enlarged in the transverse direction, is arranged across the lower combustion chamber in the vicinity of the inlet of the throttle passage, has a hollow structure that divides the combustion gas into approximately equal amounts, and has a side wall facing the flow of the combustion gas. Or secondary to the direction of intersection A first barrier formed with a plurality of secondary air ejection holes for ejecting air and a second barrier disposed across the upper combustion chamber in the vicinity of the outlet of the throttle passage and dividing the combustion gas into substantially equal amounts. It is characterized by having.

Further, it is characterized in that the outer circumferences of the first and second barriers are covered with a refractory material.

Further, each of the first and second barriers is formed by a water pipe, and the outer periphery of the water pipe is covered with a refractory material.

Further, the upper and lower combustion chambers and the passage of the throttle portion are formed by a water pipe wall, and a high-speed gas contact portion of the water pipe wall is covered with a refractory material.

Further, the flow velocity of the combustion gas flowing into the throttle passage through the small sectional area defined between the first barrier and the lower combustion chamber is 8 to 10 m / s, and the flow inside the throttle passage is The velocity is 6 to 10 m / s, and the flow velocity of the combustion gas flowing out through the minimum cross section defined between the second barrier and the upper combustion chamber is 4
It is characterized by being ~ 6 m / s.

Further, the width of the second barrier is not smaller than the width of the throttle passage.

Further, the main flow direction of the combustion gas flowing into the throttle passage is characterized by an angle with respect to the axis of the throttle passage not larger than 90 ° and not smaller than 30 °.

Further, it is characterized in that the average gas residence time in the area extending from the position of the secondary air injection hole of the first barrier to the combustion gas outlet of the upper combustion chamber is not less than 1 second.

The second barrier is composed of two flat plate-shaped portions, each flat plate-shaped portion has a plurality of openings and is connected by a ridge line extending in the horizontal direction, and the openings are arranged in zigzag along the ridge lines. It is characterized by

Further, the combustion gas is discharged from the upper combustion chamber to the atmosphere through the heat recovery section.

Further, the combustion gas is characterized in that it is discharged from the upper combustion chamber through the water injection gas cooling chamber and the gas exhaust fan into the atmosphere.

[0018]

By providing the first barrier, the throttle passage and the second barrier in the incinerator as described above, these have the following effects.

(A) Operation of the first barrier By providing the first barrier across the lower combustion chamber in the vicinity of the inlet of the throttle passage, secondary air is blown into the lower combustion chamber from the inside of the first barrier. , The secondary air is mixed and reacted with unburned gas rising from the grate part or the fluidized sand layer part.

Also, the unburnt gas flow is braked in the lower combustion chamber by the first barrier, and the gas residence time in the lower combustion chamber is lengthened.

Further, a gas (including a part of unburned gas) which has substantially completed combustion by reacting with oxygen in the lower combustion chamber is caused to flow for approximately 2 minutes, the flow velocity is increased, and the gas is made to collide in the upper throttle passage.

(B) Action of throttle passage The gases diverted in the first barrier collide with each other in the throttle passage squeezed in the transverse direction, and the flow velocity is 8 to 10 m / s on average. The gas flows directly collide with each other as compared with the diffusive mixing by the vortex flow, so that the degree of mixing becomes extremely high.

Since the cross-sectional area of the throttle passage after merging is set so that the gas flow velocity is 6 to 10 m / s on average, it passes through the vicinity of the wall surface as compared with the case where the throttle passage is not provided. The amount of unburned gas can be made extremely small.

Further, the throttle passage allows the unburned gas and the secondary air to be mixed and retained as necessary to complete the reaction.

(C) Action of Second Barrier By providing the second barrier in the vicinity of the outlet of the throttle passage, across the upper combustion chamber, it is possible to prevent blowout of unburned gas. In particular, since the width l ₂ of the second barrier is set to be equal to or larger than the width l _{1 of} the throttle passage, the action of confining the unburned gas that tries to pass through the wall surface of the throttle passage in the throttle passage is large.

The second barrier damps the gas flow that has collided and merged in the throttle passage (mostly, it is damped by colliding with the lower surface of the second barrier), so that unburned gas and air are separated. The mixing is further promoted.

Further, by providing the second barrier,
When a cooling unit, such as a boiler water pipe wall, is provided on the upper portion of the cooling unit, it is possible to block the radiant heat absorption effect on the throttle passage space from there, so keep the gas temperature in the throttle passage high without lowering it. Therefore, the reaction is not lowered.

Further, since the second barrier is covered with the refractory material, heat radiation from the refractory material surface can be given to the gas body in the throttle passage, and the reaction is further promoted.

In the present invention, the above-mentioned three actions A, B, C of the first barrier, the throttle passage and the second barrier are organically combined to exert their combined action.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. It should be understood that the present invention is not limited to the examples below. 1 and 2 are views showing the structure of an incinerator according to the present invention, FIG. 1 is a longitudinal sectional view, and FIG. 2 is AA of FIG.
FIG. As shown, the incinerator 10 has a furnace wall 11
Surrounded by, the fluidized sand layer 12, the lower combustion chamber 13,
A throttle passage 14 and an upper combustion chamber 15 are arranged.

That is, the throttle passage 14 is a passage of a constant length in which the middle of the combustion chamber is narrowed in the cross-sectional direction with respect to the gas flow direction to accelerate the gas passage velocity, and the lower portion thereof is the lower combustion chamber 13. The upper combustion chamber 15 is located above. A first barrier 16 is disposed across the lower combustion chamber 13 near the inlet of the throttle passage 14 so as to divide the combustion gas into an approximately equal amount, and the combustion gas near the outlet of the throttle passage 14 is substantially equal. A second barrier 17 is arranged across the upper combustion chamber 15 so as to divide the quantity.

The first portion arranged near the inlet of the throttle passage 14
The barrier has a hollow structure whose outer periphery is covered with a refractory, and has a plurality of secondary air ejection holes for ejecting secondary air on the bottom and sides thereof in a direction facing or intersecting with the flow of combustion gas. 16a is formed. Further, the first barrier 16 may be formed of a water pipe, and the outer peripheral surface thereof may be covered with a refractory material. The second barrier 17 disposed near the outlet of the throttle passage 14 has a structure in which the outer peripheral surface is covered with a refractory material,
In order to prevent dust accumulation, it is desirable that the upper end surface be convex. Also, this second barrier 17 is formed by a water pipe,
The outer peripheral surface may be covered with a refractory material.

Further, the second barrier 17 has a hollow structure like the first barrier 16, and a plurality of secondary air is ejected from the side wall in a direction facing or intersecting with the flow direction of the unburned gas. A secondary air ejection hole may be provided.

Below the fluidized sand layer 12, a widbox 1
8 is provided, and a primary air blowing port 20 is provided on a side portion of the wid box 18. In addition, the lower combustion chamber 13
The side furnace wall 11 is provided with an incinerator inlet 19. The fluidized sand layer 12 is fluidized by the primary air blown from the primary air blowing port 20. When the incinerated material is introduced into the incinerated material inlet 19 here, the incinerated material is gasified (including a large amount of unburned gas) by the high temperature of the fluidized sand layer 12 and rises.

This gas is used in the upper furnace wall 1 of the lower combustion chamber 13.
Braking is performed by the first and first barriers 16 so as to stay longer in the lower combustion chamber 13. Secondary air is blown into the lower combustion chamber 13 through the secondary air ejection holes 16a of the first barrier 16 and mixed with the unburned gas. Further, the gas that has completed the combustion in the lower combustion chamber 13 (including some unburned gas) is diverted to a substantially equal amount by the first barrier 16.
Through the passage between the furnace wall 11 and the first barrier 16, they collide and merge at the throttle passage 14. Since the cross-sectional area of the throttle passage 14 is small, the velocity of the gas is increased and the secondary air and the unburned gas are vigorously stirred.

The gas accelerated in the throttle passage 14 flows into the upper combustion chamber 15 having a wide cross section. Throttle passage 14
Since the second barrier 17 is arranged in the vicinity of the outlet of the gas, the gas is again braked, divided into approximately equal amounts, and passed through the passage between the furnace wall 11 and the second barrier 17, They merge again in the upper combustion chamber 15.

The combustion gas which has been almost completely mixed in the above process is retained in the upper combustion chamber 15 for a predetermined period of time while being kept at a high temperature, and then discharged from the gas outlet. Here, the average gas retention time from the position of the secondary air ejection hole 16a of the first barrier 16 to the combustion gas outlet of the upper combustion chamber 15 is set to be 1 second or more.

Also, the first barrier 16 and the lower combustion chamber 1
The angle θ with respect to the axis Y of the throttle passage 14 in the main flow direction of the gas flowing into the throttle passage 14 through the upper furnace wall 3 is 90 °>θ> 30 °. ..

Further, the average flow velocity V1 of the gas flowing into the throttle passage 14 through the space between the first barrier 16 and the upper furnace wall of the lower combustion chamber 13 is set to 8 m / s to 10 m / s, The average flow velocity V2 of the gas passing through the passage 14 is 6 m / s to 10 m.
/ S, flow out from the throttle passage 14, and the second barrier 1
The average flow velocity of the gas passing between 7 and the lower furnace wall of the upper combustion chamber 15 is set to 4 m / s to 6 m / s.

As described above, the average flow velocity V1 of the gas flowing into the throttle passage 14 narrowed so that the gases divided by the first barrier 16 collide and merge with each other is set to 8 m / s to 10 m / s. Compared with the diffusive mixing due to the vortex around the barrier, the gases directly collide with each other, so that the mixing intensity becomes extremely high. Further, since the cross-sectional area is set so that the average flow velocity of the gas passing through the throttle passage 14 is 6 m / s to 10 m / s, the unburned gas that passes through the vicinity of the furnace wall surface as compared with the case where the throttle passage 14 is not provided is used. The amount of gas can be extremely small.

Further, by providing the second barrier 17, most of the gas flow colliding and converging in the throttle passage 14 collides with the lower surface of the second barrier 17 and is damped.
Further mixing is promoted. Further, since the second barrier 17 is covered with a refractory material, heat radiation from the refractory material surface can be given to the gas body of the throttle passage 14 to further promote the reaction. Further, the width l ₂ of the second barrier 17 needs to be equal to or larger than the width l ₁ of the throttle passage 14 in order to prevent the unburned gas from being blown out, and particularly to confine it in the throttle passage 14.

3 to 5 are views showing another structure of the incinerator of the present invention. FIG. 3 is a longitudinal sectional view, FIG. 4 is an enlarged view showing the structure of the second barrier, and FIG. 5 is shown in FIG. It is a BB sectional view. This incinerator is a stoker furnace, and a lower combustion chamber 31, a throttle passage 32, and an upper combustion chamber 33 above a grate 34 are sequentially arranged from the bottom. The furnace wall 37 has a water tube wall 37a on the outer side and a refractory material 37b on the inner side.

A first barrier 35 is provided in the lower combustion chamber 3 so as to divide the combustion gas into an approximately equal amount near the inlet of the throttle passage 32.
A second barrier 36 is disposed across the upper combustion chamber 33 so that the combustion gas can be divided into approximately equal amounts in the vicinity of the outlet of the throttle passage 32. An incineration material inlet 38 is provided at a side portion of the lower combustion chamber 31, and an upper combustion chamber 33 is provided.
A heat recovery unit 39 such as a boiler is disposed on the upper part of the.

The first barrier 35 has substantially the same structure as the first barrier 16 of the incinerator shown in FIGS. 1 and 2. Further, the first barrier 35 may be formed of a water pipe, and the outer peripheral surface thereof may be covered with a refractory material.

As shown in FIG. 4, for example, the second barrier 36 has three headers 40 connected by a water pipe 41 and an outer surface thereof covered with a refractory material 43.

The angle θ with respect to the axis Y of the throttle passage 32 in the main flow direction of the gas flowing into the throttle passage 32 between the first barrier 35 and the upper furnace wall of the lower combustion chamber 31, The average flow velocity V1 of unburned gas flowing into the throttle passage 32 through the space between the first barrier 35 and the upper furnace wall of the lower combustion chamber 31, the average flow velocity V2 of unburned gas passing through the throttle passage 32,
The average flow velocity V3 of the unburned gas flowing out from the throttle passage 32 and passing between the second barrier 36 and the lower furnace wall of the upper combustion chamber 33 should be the same as in FIGS. 1 and 2. To do.

With the structure of the incinerator as described above, the gas (including a large amount of unburned gas) that is generated by burning in the grate 34 and flows into the lower combustion chamber 31 is the first barrier 35.
While being mixed with an appropriate amount of secondary air blown in from the first barrier 35, the first barrier 35 splits the flow in two directions into substantially equal amounts, and the flow is divided between the first barrier 35 and the side wall of the lower combustion chamber 31. 8m
/ S to 10 m / s, the collision is made at the entrance of the throttle passage 32, and they are merged and vigorously mixed, and the reaction between the unburned gas and oxygen rapidly progresses.

The gases merged at the inlet of the throttle passage 32 pass through the passage while mixing while maintaining the flow velocity of 6 m / s to 10 m / s, and collide with the second barrier 36 at the outlet,
By changing the flow direction, the second barrier 36 and the upper combustion chamber 3
4m / s ~
It flows into the upper combustion chamber 33 at a flow velocity of 6 m / s.

The combustion gas which has been almost completely mixed in the above process is retained in the upper combustion chamber 33 for a predetermined time while being kept at a high temperature, and then discharged from the gas outlet. Here, the average gas retention time of the first barrier 32 up to the combustion gas outlet of the upper combustion chamber 33 is set to 1 second or more.

The first barrier 3 in the incinerator shown in FIG.
5, the function of the throttle passage 32 and the second barrier 36 is as shown in FIG.
First barrier 16, throttle passage 14 and second barrier 17 of
The detailed description thereof is omitted. Also,
In the incinerator of FIG. 3, the second barrier 36 is the heat recovery unit 3
When the water tube wall of the boiler is provided in 9, since the radiation heat absorbing action on the space of the throttle passage 32 is shielded from this water wall, the gas temperature of the throttle passage 32 can be kept high without lowering, Does not reduce the reaction.

FIG. 6 is a vertical sectional view showing another structure of the incinerator of the present invention. As shown in the figure, the incinerator is configured to include a lower combustion chamber 13, a throttle passage 14, an upper combustion chamber 15, and a heat recovery device 39. The incinerator of FIG. 6 has a fluidized sand layer 112 below the lower combustion chamber 13, and has a first barrier 116 having a secondary air ejection hole 16a above and a throttle passage 14
2 has a second barrier 117 on the upper part thereof, and the lower combustion chamber 13 has an elongated shape as compared with the incinerator of FIG. Further, a combustion material charging port 19 is provided on the furnace wall below the lower combustion chamber 13.
And an auxiliary air ejection hole 52 is provided in the upper part thereof.

The fluidized sand layer 112 is a swirl type fluidized bed. That is, there are areas where the medium (sand) flows relatively strongly above and areas where the medium flows relatively weakly below, and these areas are the upper and lower sections where the medium in each part is It forms a fluidized bed which moves and swirls towards two zones. The two different zones are formed by varying the air flow supplied to each zone from the window box 18. Window box 1
Air to 8 is supplied through line 50. Such a circulation type fluidized bed is already known, and is disclosed in, for example, US Pat. Nos. 4,452,155 and 4,823,740.

The cross section of the first barrier 116 is composed of an annular portion and a corner portion integrally formed on the upper portion of the annular portion. The surface of the corner is inclined with respect to the horizontal direction so that the falling ash can easily slide off without accumulating. As shown in FIGS. 6 and 7, the second barrier 117 is composed of two flat plate-shaped portions in which three headers 40 are connected by a plurality of water pipes 41 and a refractory 43 covers the headers. The second barrier 117
4 is different from the second barrier shown in FIG. 4 in that the second barrier in FIG. 7 is provided with a plurality of openings 62 in a zigzag shape along the header 40 corresponding to the ridge 64. The mixed gas passing through the throttle passage 14 flows through the opening 62 of the second barrier 117 to generate a large number of small swirls, further promoting the mixing of oxygen and unburned gas.

Incidentally, the first barrier 1 in the incinerator of FIG.
16, the function of the throttle passage 14 and the second barrier 117 is as follows.
Since the first barrier 16, the throttle passage 14 and the second barrier 17 in FIG. 1 are substantially the same, detailed description thereof will be omitted. In addition, the incinerator of FIG. 6 is similar to the incinerator of FIG.
In the case where the heat recovery unit 39 is provided with a cooling unit such as a water pipe wall of the boiler 17, the radiant heat absorption effect on the space of the throttle unit passage 14 is shielded from the cooling unit 17, so that the gas temperature of the throttle unit passage 14 is lowered. It can be kept at high temperature without lowering the reaction.

FIG. 8 is a vertical sectional view showing another structure of the incinerator of the present invention. Similar to the incinerator shown in FIG. 6, this incinerator is equipped with a fluidized sand layer 112 having a swirl type fluidized bed, a lower combustion chamber 13, a throttle passage 14, and a large number of secondary air ejection holes 16
This is a configuration including a first barrier 217 having a and a second barrier 217. An incineration material inlet 19 is provided below the lower combustion chamber 13, and an auxiliary air ejection hole is provided above the incineration material inlet 19.

The incinerator shown in FIG. 8 is equipped with a gas cooling tower 60 having a large number of water injection nozzles 66 in place of the heat recovery device 39 shown in FIGS. The gas cooling tower 60 is operated to cool the exhaust gas with the water injected from the water injection nozzle 66. This exhaust gas cooling is performed to prevent devices such as an induction fan connected to the incinerator from being damaged by heat. An induction fan is provided for sucking the mixed gas from the incinerator and discharging it into the atmosphere.

The first barrier 1 in the incinerator shown in FIG.
16, the function of the throttle passage 14 and the second barrier 217 is as follows.
Since the first barrier 16, the throttle passage 14 and the second barrier 17 in FIG. 1 are substantially the same, detailed description thereof will be omitted. Further, in the incinerator of FIG. 8, the second barrier 217 shields the radiation heat absorbing action from the gas cooling tower 60 to the space of the throttle passage 14, so that the gas temperature of the throttle passage 14 is maintained at a high temperature without lowering. It is possible to reduce the reaction.

The second barrier 217 of FIG. 8 is made of a refractory material and has a hole through which a refrigerant passes. The top surface of the barrier 217 has a shape very similar to that of the second barrier of FIG. 1 so that dust and ash will not be deposited. Figure 8
The incinerator shown in (1) is for incineration of low-calorie incinerators such as municipal waste, and is suitable for a relatively small-scale plant.

As described above, according to the above-described embodiment, the collision effect between the gases, the collision between the gas and the first and second barriers, and the gas stirring and mixing action are performed. It is possible to almost completely prevent the fuel gas from being discharged from the gas outlet as it is.

[0060]

As described above, according to the present invention, the following excellent effects can be obtained.

(1) The unburned gas and the secondary air are almost completely mixed by the strong stirring force using the kinetic energy of the combustion gas or the combustion gas and the barrier gas themselves, and the unburned gas is not burned. It is possible to prevent gas from slipping through.

(2) Since the unburnt gas and the secondary air have a good mixing property, the amount of secondary air blown into the furnace can be reduced (the air ratio can be reduced) as compared with the conventional example, and the combustion gas temperature can be reduced. Since it can be maintained at a high temperature, decomposition of harmful substances such as dioxins is promoted.

(3) Due to the above effects, the amount of unburned gas such as CO discharged from the incinerator of the present invention such as municipal waste can be suppressed to a minimum, and the emission of harmful substances such as dioxins can be suppressed. It is possible to reduce.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of an incinerator according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical cross-sectional view showing the structure of the incinerator of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a structure of a second barrier.

5 is a sectional view taken along line BB of FIG.

FIG. 6 is a vertical cross-sectional view showing another structure of the incinerator of the present invention.

7 is a diagram showing the structure of the second barrier of FIG.

FIG. 8 is a vertical cross-sectional view showing another structure of the incinerator of the present invention.

[Explanation of symbols]

 10 incinerator 11 furnace wall 12 fluidized sand layer 13 lower combustion chamber 14 narrowed passage 15 upper combustion chamber 16 first barrier 17 second barrier 18 window box 19 incinerator inlet 20 primary air inlet 30 incinerator 31 lower combustion Chamber 32 Throttle passage 33 Upper combustion chamber 34 Grate 35 First barrier 36 Second barrier 37 Furnace wall 38 Incinerator input 39 Heat recovery 40 Header 41 Water pipe 43 Refractory 50 Piping 52 Auxiliary air jet 60 Gas Cooling tower 62 Opening 64 Ridge 66 Water injection nozzle 116 First barrier 117 Second barrier 217 Second barrier

Continued Front Page (72) Inventor Yu Yoshida 11-1 Haneda-Asahicho, Ota-ku, Tokyo Inside EBARA CORPORATION

Claims (12)

[Claims] 1. An incinerator is combusted in a grate part or a fluidized sand layer part, and the generated combustion gas is introduced into a combustion chamber connected to the upper part and mixed with secondary air in the combustion chamber to maintain a constant residence time. In an incinerator configured to complete combustion by making the middle of the combustion chamber narrow in the cross-sectional direction with respect to the gas flow direction and extending a predetermined distance, a portion of the combustion chamber A lower combustion chamber that is formed below the throttle passage and that is enlarged in the transverse direction; an upper combustion chamber that is defined by a portion of the combustion chamber that is above the throttle passage and that is enlarged in the transverse direction A hollow structure that is disposed in the vicinity of the inlet of the throttle passage and that crosses the lower combustion chamber and divides the combustion gas into substantially equal amounts, and has a side wall that faces or intersects the flow of the combustion gas. A plurality of secondary air jets A second barrier that forms a secondary air ejection hole and a second barrier that is disposed in the vicinity of the outlet of the throttle passage across the upper combustion chamber and divides the combustion gas into substantially equal amounts. And a combustion furnace. 2. The incinerator according to claim 1, wherein the outer circumferences of the first and second barriers are covered with a refractory material. 3. The incinerator according to claim 1, wherein each of the first and second barriers is formed of a water pipe, and the outer periphery of the water pipe is covered with a refractory material. 4. The upper and lower combustion chambers and the throttle passage are formed by a water pipe wall, and a high-speed gas contact portion of the water pipe wall is covered with a refractory material. The incinerator described in 3. 5. The flow velocity of the combustion gas flowing into the throttle passage through a small cross-sectional area defined between the first barrier and the lower combustion chamber is 8 to 10 m / s, and the throttle is The flow velocity in the passage is 6 to 10 m / s, and the flow velocity of the combustion gas flowing out through the minimum cross section defined between the second barrier and the upper combustion chamber is 4 to 6 m / s. The incinerator according to claim 1, which is characterized in that. 6. The incinerator according to claim 1, wherein the width of the second barrier is not smaller than the width of the throttle passage. 7. The main flow direction of the combustion gas flowing into the throttle passage is at an angle with respect to the axis of the throttle passage not larger than 90 ° and not smaller than 30 °. Incinerator. 8. The average gas residence time in the area extending from the position of the secondary air injection hole of the first barrier to the combustion gas outlet of the upper combustion chamber is not less than 1 second. Incinerator. 9. The second barrier is composed of two flat plate-shaped portions, each flat plate-shaped portion having a plurality of openings and connected by a ridge line extending in a horizontal direction, the openings being zigzag along the ridge line. It is arranged in
Incinerator described. 10. The incinerator according to claim 1, 2 or 3, wherein the fluidized sand layer portion is a swirling fluidized bed. 11. The incinerator according to claim 1, wherein the combustion gas is discharged from the upper combustion chamber through a heat recovery section into the atmosphere. 12. The incinerator according to claim 1, wherein the combustion gas is discharged from the upper combustion chamber to the atmosphere through a water injection gas cooling chamber and a gas exhaust fan.