JPH05203130A - Heat reactor - Google Patents

Abstract

PURPOSE:To hold production of unburned gas to the minimum amount by a method wherein a gas passage of an obstruction wall in a combustion chamber is gradually increased in width toward one end with the shape of an inverted shade. CONSTITUTION:A narrow passage 14 is provided leading to a combustion chamber and the combustion chamber is divided into a lower combustion chamber 13 and an upper combustion chamber 15 by a first obstruction wall 16 provided at an outlet of the narrow passage and the obstruction wall 16 is provided with a gas passage 17 formed between the upper and lower combustion chambers 15 and 13 in order that combustion gas may be distributed therethrough almost evenly into both the combustion chambers. The gas passage 17 of the obstruction wall 16 is gradually increased in width toward one end at an angle to the narrow passage with the shape of an inverted shade. For this reason, the flow of the combustion gas taking place in the lower combustion chamber 13 is divided almost evenly into two branches by the obstruction wall 16 at the outlet of the narrow passage 14, each of the flow branches is increased in speed, these gas flows meet to form a swirl stream upon passing through the gas passage 17, the gas flow thus joined is discharged with force therefrom, runs along the reactor side of the upper combustion chamber 5 and becomes a reverse stream toward the center of the reactor. In doing so, reaction between unburned gas and oxygen is accelerated to hold production of the unburned gas to the minimum amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal reaction furnace for burning wastes, etc., and particularly for improving mixing of unburned gas from a fire bed with secondary air, and The present invention relates to a thermal reaction furnace capable of suppressing scattering outside the furnace.

[0002]

2. Description of the Related Art Conventionally, various techniques have been proposed as a technique for suppressing unburned gas in combustion of wastes and the like. For example, in Japanese Patent Laid-Open No. 63-279013,
"NOx and unburned gas suppressor of fluidized bed incinerator" is described. According to the above technique, a hollow barrier is arranged across the combustion chamber, and the vortex flow generated by the combustion gas rising in the opening between the furnace side wall and the barrier causes oxygen and unburned gas to be ejected from the ejection holes of the hollow barrier. It promotes mixing with gas and suppresses the emission of harmful substances such as unburned gas.

[0003]

However, in the above technique as well, the mixing of oxygen (secondary air) and unburned gas depends on the penetrating force of the ejected air (blowing velocity of the secondary air). The agitation force abruptly weakens with increasing distance from the holes, and there is a risk that unburned gas and air will not be mixed with each other because the unburned gas slips through a region that is not affected by the secondary air jet. In addition, if the number of air jets is increased to prevent this, there arises a problem that the penetrating force of jetted air is weakened.

Further, when the rising flow velocity for mixing and stirring is increased, unburned carbon entrained in the combustion gas and the flowing medium also pass through the throttle as they are, so the gas flow velocity is 2 m / s. Limited to the extent. Therefore, there is a problem that the upper combustion chamber is generally configured to be larger than the lower combustion chamber. The present invention has been made in view of the above points, even if the passing gas flow velocity of the throttle portion is fast, unburned carbon and the scattering of the fluid medium are minimized, and the unburned gas passes through unreacted. It is an object of the present invention to provide a thermal reactor in which the reaction between unburned gas and oxygen proceeds reliably and rapidly, and the unburned gas can be suppressed to a minimum.

[0005]

In order to achieve the above object, in the present invention, the incinerated matter 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, In a thermal reaction furnace configured to mix with secondary air in a combustion chamber to maintain a constant residence time to complete combustion, the combustion chamber is squeezed in the transverse direction with respect to the gas flow direction, and the combustion chamber has a constant distance. The expansion part is formed again with the passage of No. 1, a barrier of Yamakasa structure is provided at the outlet of the passage of the restriction, a lower combustion chamber is formed below the barrier, and an upper combustion chamber is formed above the barrier. With a gas passage of a certain distance,
The upper combustion chamber is provided with a plurality of secondary air blowing ports for ejecting secondary air in a direction facing or intersecting with the flow of combustion gas at the barrier outlet, and the gas passage of the barrier is configured to be widened toward the end. is there.

In the above thermal reaction furnace, the barrier (first barrier) provided at the outlet of the throttle passage is covered with a refractory material, or the barrier is formed with a water pipe, and the outer circumference is made of a refractory material. It is preferable that the upper and lower combustion chambers and the throttle passage are formed of a water pipe wall, and the high-speed gas contact portion thereof is covered with a refractory. The width of the first barrier may be equal to or larger than the width of the narrowed passage, and the gas passage provided in the barrier forms a divergent angle that forms an angle of 30 ° to 60 ° with respect to the furnace wall axis. This makes it possible to improve the mixing of unburned gas and secondary air by making the combustion gas a reversing swirl flow, and the inclination angle of the barrier cap is 30 ° with respect to the furnace wall axis. The range is preferably in the range of -60 °, whereby unburned carbon and scattered fluidized medium can be returned to the lower combustion chamber.

Further, in the above thermal reaction furnace, another barrier (second barrier) is arranged in the upper combustion chamber by sloping upward from the side surface of the furnace wall, and the upper end of the slope is bent vertically toward the ceiling of the furnace wall. An opening is formed between the ceiling of the furnace wall and the barrier, and a combustion gas discharge port is provided on the side surface of the furnace wall inside the barrier. In the thermal reactor of the present invention configured as described above, the flow velocity of the combustion gas passing through the minimum cross section of the throttle passage and flowing into the gas passage of the first barrier is set to 8 to 10 m / s, and Of 10 to 15 m / s, and the flow rate of the combustion gas flowing out through the minimum cross section of the upper combustion chamber is 3
It is preferable to operate at ~ 6 m / s, and the average gas residence time from the position of the secondary air blowing hole at the inlet of the throttle passage to the outlet of the combustion gas of the lower combustion chamber is set to 1 second or more, and The average gas residence time from the position of the secondary air blowing hole at the gas passage outlet of the first barrier to the combustion gas outlet of the upper combustion chamber is preferably set to 3 seconds or more.

[0008]

As described above, the throttle passage is provided in the middle of the combustion chamber, and the lower portion of the first barrier disposed at the outlet of the throttle portion is the lower combustion chamber and the upper portion is the upper combustion chamber, and the passage passes through the gas passage of the barrier. Since the gas passages are arranged across the upper and lower combustion chambers in the barrier so as to divide the combustion gas into substantially equal amounts, the combustion gas generated in the lower combustion chamber is generated in the barrier at the outlet of the throttle passage. After accelerating each branch flow for about two minutes, the gas passage of the barrier is divergent and angled with respect to the cross-sectional direction. After flowing out along the furnace side, it becomes a reverse flow toward the center. That is, by forming the gas passage of the barrier to widen toward the end so as to dampen the flow of the combustion gas, and to form the Yamakasa structure, the operating energy of the combustion gas is maximally utilized to obtain a reverse flow. It is possible to suppress the scattering of unburned carbon and fluidized medium to a minimum, and the unburned gas does not escape unreacted, and the reaction between the unburned gas and oxygen proceeds reliably and rapidly, Gas can be suppressed to a minimum.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these. Example 1 FIGS. 1, 2 and 3 are sectional structural views of a thermal reaction furnace showing an example of the present invention, FIG. 1 is a longitudinal sectional view, and FIG. 2 is AA of FIG.
A sectional view and FIG. 3 are sectional views taken along line BB of FIG. As shown in the figure, the thermal reaction furnace 10 is surrounded by a furnace wall 11, and a fluidized sand layer 12, a lower combustion chamber 13, a throttle passage 14, a first barrier 16, a combustion gas passage 17 of a first barrier, in order from the bottom. The upper combustion chamber 15 and the second barrier 23 are arranged. That is, the throttle passage 14 is a passage having 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. Barrier 1
The upper part of 6 is the upper combustion chamber 15. Throttle passage 14
So that the combustion gas is divided into approximately equal amounts near the outlet of the first
A barrier 16 of the above is disposed across the lower combustion chamber 13, and
The second barrier 23 is arranged across the upper combustion chamber 15 so that the combustion gas is discharged from the side surface of the furnace wall 11.

A first member disposed near the outlet of the throttle passage 14
The barrier has a Yamakasa structure in which the outer periphery is covered with a refractory, and the gas passage 17 of the first barrier 16 is formed so as to widen toward the end and form an angle with respect to the cross-sectional direction. Further, the first barrier 16 and the second barrier 23 may be formed by a water pipe, and the outer peripheral surface thereof may be covered with a refractory material. Further, the first barrier 16 may have a Yamakasa structure, and a plurality of secondary air suction ports 22 for ejecting secondary air may be provided in a direction facing or intersecting the flow of the combustion gas at the barrier outlet. ..

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, unburned carbon and scattered fluidized medium) by the high temperature of the fluidized sand layer 12 and rises. This gas is braked by the lower combustion chamber 13, the upper furnace wall 11 and the first barrier 16 so as to stay in the lower combustion chamber 13 for a long time. Secondary air is blown therein through the secondary air blowing port 22a to mix the secondary air with unburned gas. 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. Here, the average gas residence time of the first barrier 16 to the combustion gas outlet of the lower combustion chamber 13 is set to 1 second or more.

The gas accelerated in the throttle passage 14 is
Flow into the gas passages 17 at both ends of the barrier 16. Since the gas passage has a divergent shape and is angled in the cross-sectional direction, when the gas is jetted into the upper combustion chamber 15 while swirling in the gas passage, it rises along the furnace wall 11 and from the middle. The reverse flow 21 is formed toward the center and collides and merges. Further, the penetrating force of the secondary air from the secondary air blowing port 22b causes the secondary air to be vigorously stirred with the unburned gas.
The combustion gas which is almost completely mixed in the above process is
While maintaining the high temperature at 5, after staying for a predetermined time, it is discharged from the gas outlet. Here, the average gas residence time of the first barrier 16 to the combustion gas outlet of the upper combustion chamber 15 is set to 3 seconds or more. On the other hand, the unburned carbon and the scattered medium are returned to the lower combustion chamber 13 below the first barrier 16 by the reverse flow 21.

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 gas passage 17 through the space between the first barrier 16 and the upper furnace wall of the lower combustion chamber 13 is:
The angle is set to 60 ° ≧ θ ≧ 30 °. Further, the gas flowing out through between the first barrier 16 and the upper furnace wall of the lower combustion chamber 13 passes through the minimum cross section of the throttle passage, and flows into the gas passage 17 of the first barrier. Average flow velocity V1
Is 8 m / s to 10 m / s, the average flow velocity V2 of the gas passing through the gas passage 17 is 10 m / s to 15 m / s, and the gas flows out from the gas passage 17 to the second barrier 23 and the upper combustion chamber 15
The average flow velocity V3 of the gas passing between the lower furnace wall of the
/ S to 6 m / s. In addition, the second barrier 23 is configured such that the barrier is inclined upward in the upper combustion chamber 15, the upper end of the inclination is arranged vertically upward, and the combustion gas is discharged from the side surface of the furnace wall 11. Further, the second barrier 23 may be formed of a water pipe and the outer periphery thereof may be covered with a refractory material.

Embodiment 2 FIGS. 4 to 7 are sectional views showing the structure of another thermal reactor of the present invention, FIG. 4 is a longitudinal sectional view, and FIG. 5 is an enlarged view showing the structure of a first barrier. 6 is a cross-sectional view taken along line CC of FIG. 4, and FIG. 7 is D of FIG.
It is a -D sectional view. The thermal reaction furnace of this embodiment is a stoker furnace, and in the figure, the lower combustion chamber 31 above the grate 34,
The throttle passage 32 and the upper combustion chamber 33 are arranged in order 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.

The first barrier 36 is provided near the outlet of the throttle passage 32 so as to divide the combustion gas into substantially equal amounts.
2 is disposed across the upper gas passage of 2, and the lower combustion chamber 31
An incinerator inlet 38 is provided on the side of the upper combustion chamber 3
A heat recovery unit 39 such as a boiler is arranged on the upper part of the unit 3. The first barrier 36 has substantially the same structure as the first barrier 16 of the thermal reactor of the first embodiment, but the first barrier 36 is the same.
Is made of a water pipe, and its outer peripheral surface is covered with a refractory material. For example, as shown in FIG. 5, the first barrier is formed by connecting three headers 40 with water pipes 41 and 42 and covering the outer surface thereof 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 gas passage 35 through the space between the first barrier 36 and the upper furnace wall of the lower combustion chamber 31,
An average velocity V1 of unburned gas flowing into the gas passage 35 through the space between the first barrier 36 and the upper furnace wall of the lower combustion chamber 31;
The average flow velocity V2 of the unburned gas passing through the gas passage 35 and the average flow velocity V3 of the unburned gas flowing out of the gas passage 35 and passing between the lower combustion chamber wall and the upper combustion chamber 33 are the same as those in the first embodiment. To be By constructing the thermal reaction furnace as described above, the gas generated by burning in the fluidized sand layer 12 or the grate 34 and flowing out to the lower combustion chambers 13 and 32 is a gas (unburned gas and unburned carbon or scattered gas). The first barriers 16 and 36 divide the flow into two substantially equal amounts in two directions, and the first barriers 16 and 36 and the side walls of the lower combustion chambers 13 and 32 are respectively 8 m / The speed is increased to s to 10 m / s, and the gas collides near the inlets of the gas passages 17 and 35, merges and vigorously mixes, and the reaction of unburned gas and oxygen rapidly progresses.

When the gases joined at the inlets of the gas passages 17 and 35 are jetted from the outlets of the gas passages 17 and 35 while being swirled while mixing and maintaining a flow velocity of 10 m / s to 15 m / s. Ascend along the furnace walls 11, 44,
The reverse flows 21 and 45 are formed toward the center from the middle and collide and merge. Furthermore, the secondary air is vigorously agitated with the unburned gas by the penetrating force of the secondary air from the secondary air blowing ports 22b and 46b. On the other hand, unburned carbon and scattered fluid medium are the reverse flow 2
A large amount is returned to the lower combustion chambers 13 and 32 below the first barriers 16 and 36 by 1, 45. The combustion gas which is almost completely mixed in the above process is discharged from the gas outlet after staying for a predetermined time while maintaining the high temperature in the upper combustion chambers 15, 33.
Here, the upper combustion chamber 15 of the first barriers 16, 36,
The average gas residence time to the combustion gas outlet 33 is 3 seconds or more, and the average gas residence time to the combustion gas outlets of the lower combustion chambers 13 and 32 below the first barrier is 1 second or more. Try to be.

As described above, according to the above-described embodiment, reductive combustion in the lower combustion chamber and oxidative combustion in the upper combustion chamber are performed, and the swirl reversal of the combustion gas is formed by forming the end wall of the gas jet passage of the first barrier. Since motion is generated to effectively reburn and recover unburned carbon and scattered fluid medium, it is possible to almost completely prevent problems due to conventional unburned gas discharge and outflow of unburned carbon and scattered fluid medium. It will be possible.

[0019]

As described above, according to the present invention, the following excellent effects can be obtained. (1) The strong reversal flow or stirring force using the kinetic energy of the combustion gas itself or the combustion gas and the barrier gas itself minimizes the outflow of unburned carbon and scattered fluidized medium, and Mixing with the secondary air is almost complete, and it is possible to prevent the unburned gas from passing through. (2) Since the unburnt gas and the secondary air have a good mixing property, it is possible to reduce the amount of secondary air blown into the furnace (reduce the air ratio) and raise the combustion gas temperature to a higher temperature than in the conventional example. Since it can be maintained, the decomposition of harmful substances such as dioxins is promoted. (3) Due to the above effects, the thermal reactor of the present invention can minimize the amount of unburned gas such as CO discharged from the incinerator of wastes, and also discharges harmful substances such as dioxins. It is possible to reduce.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the structure of a thermal reaction furnace of the present invention.

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

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a vertical cross-sectional view showing the structure of the thermal reaction furnace of the present invention.

FIG. 5 is an enlarged cross-sectional view showing a structure of a second barrier.

6 is a cross-sectional view taken along line CC of FIG.

7 is a cross-sectional view taken along the line DD of FIG.

[Explanation of symbols]

10, 30: Thermal reactor, 11, 37: Furnace wall, 12: Fluidized sand layer, 13, 31: Lower combustion chamber, 14, 32: Throttle passage, 15, 33: Upper combustion chamber, 16, 36: 1st Barriers, 17, 35: Gas passage, 18: Widbox, 1
9, 38: Incinerator inlet, 20: Primary air inlet, 2
1, 45: reverse flow, 22, 46: secondary air inlet, 2
3: Second barrier, 34: Grate, 39: Heat recovery part, 4
0: header, 41, 42: water pipe, 43: refractory material, 44:
Water cooling wall

Front page continuation (72) Inventor Keiichi Sato 11-1 Haneda-Asahi-cho, Ota-ku, Tokyo Inside EBARA CORPORATION

Claims (8)

[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 the thermal reaction furnace configured to complete combustion, the combustion chamber is throttled in the transverse direction with respect to the gas flow direction to form a throttle portion that expands again with a passage of a certain distance. A barrier of Yamakasa structure is provided at the outlet of the throttle passage, a lower combustion chamber is formed below the barrier, and an upper combustion chamber is formed above the barrier.
In the upper combustion chamber, a plurality of secondary air blowing ports for ejecting secondary air in a direction facing or intersecting the flow of the combustion gas at the barrier outlet is arranged, and the gas passage of the barrier is configured to be widened toward the end. Characteristic thermal reactor. 2. The thermal reactor according to claim 1, wherein the outer periphery of the barrier provided at the outlet of the throttle passage is covered with a refractory material. 3. The thermal reactor according to claim 1, wherein the barrier is formed of a water pipe, and the outer periphery of the barrier is covered with a refractory material. 4. The thermal reactor according to claim 1, wherein the upper and lower combustion chambers, the barrier and the narrowed passage are formed by water pipe walls, and the high-speed gas contact portion is covered with a refractory. 5. The thermal reactor according to claim 1, wherein the width of the barrier provided at the outlet of the throttle passage is equal to or larger than the width of the throttle passage. 6. The thermal reactor according to claim 1, wherein the gas passage provided in the barrier is at an angle of 30 ° to 60 ° with respect to the furnace wall axis. 7. The thermal reaction furnace according to claim 1, wherein an inclination angle of the mountain cap of the barrier is in a range of 30 ° to 60 ° with respect to a furnace wall axis line. 8. A separate barrier is arranged in the upper combustion chamber so as to incline upward from the side wall of the furnace wall and the upper end of the slope is bent toward the ceiling of the furnace wall vertically above the furnace wall ceiling and the barrier. The thermal reaction furnace according to claim 1, wherein an opening is formed between the two, and a combustion gas discharge port is provided on a side surface of the furnace wall inside the barrier.