JPH1151343A - Fluidized bed incinerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the remaining of unburned combustible in incinerating municipal waste and industrial waste. SOLUTION: A primary combusting chamber 2 is arranged to the lower part of a furnace main body 1, a secondary combusting chamber 3 is arranged to the upper part of it, a throttling part 4 is arranged between the primary combusting chamber 2 and the secondary combusting chamber 3, and a fluidized bed 6 is formed to the primary combusting chamber 2. The shapes of the primary combusting chamber 2 and the throttling 4 in the cross sectional view are rectangular. Multiple nozzles 14 generating vortex flow by blowing the secondary combustion air into the primary combustion chamber 2 are arranged to the right, left and central parts of the upper edge part of the back wall 2b of the primary combusting chamber 2 and to the right, left and central parts, and both right and left edge parts of the upper part of the front wall 2a of it. The sizes of point blowing holes of the nozzles 14 of the back wall 2b are formed larger than the sizes of the point blowing holes of the nozzles 14 at the right, left and central part of the front wall 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed incinerator for incinerating municipal waste and industrial waste.

In this specification, the left side of FIGS. 1 to 4 is referred to as front, the opposite side is referred to as rear, the upper side of FIGS. 2 to 4 is referred to as left, and the opposite side is referred to as right.

[0003]

2. Description of the Related Art As a fluidized bed incinerator of this type, the present applicant firstly forms a fluidized bed by flowing a fluidized medium under a vertical cylindrical furnace body, where the incinerated material is burned. A primary combustion chamber is provided at the upper part of the furnace body, and a secondary combustion chamber is provided at an upper part of the furnace main body to burn unburned components and pyrolysis gas by secondary combustion air blown into the combustion gas. A throttle portion having a substantially rectangular horizontal cross-sectional shape is provided between the first combustion chamber and the first combustion chamber, and a second combustion air is blown to the upper end of the primary combustion chamber in a direction orthogonal to the long side direction of the throttle portion. Nozzle 1
A fluidized bed incinerator is provided in which a plurality of second nozzles for blowing out secondary combustion air in the lateral direction are provided on a wall of two long sides of a throttle section so as to face each other. (See JP-A-8-61636).

[0004]

However, according to the observation result of the combustion state in the furnace by the industrial TV camera and the temperature distribution in the furnace obtained from the analysis based on the temperature measurement of each part in the furnace, It has been found that the fluidized bed incinerator has the following problems. That is, the secondary combustion air blown out from the first nozzle presses the flow of the combustion gas against the wall surface on the side opposite to the side where the first nozzle is provided, and as a result, the combustion gas and the secondary combustion air flow. Even if air rises as a laminar flow and the secondary combustion gas is blown out from the second nozzle at the throttle portion, the second nozzle is provided so as to face each other. The flow of the combustion gas and the secondary combustion air that have flowed in is separated by the secondary combustion air blown out from the second nozzle, but rises as a laminar flow, whereby the combustion gas and the secondary combustion air flow. Mixing with working air becomes difficult. Therefore, many unburned components contained in the combustion gas are discharged without completely burning, and highly toxic dioxins are generated in the combustion exhaust gas by the dioxin precursor contained in the unburned components. . These dioxins are
It is desired to reduce the amount of dust generated by the bag filter type dust collector, because the dust is collected together with other dust but is not perfect and the post-treatment of the collected ash.

Furthermore, recently, in order to reduce the combustion fluctuation by reducing the burning speed of the incinerated material and to reduce the unburned portion, the incineration in the fluidized bed formed at the bottom of the primary combustion chamber is performed. It is considered that the portion on the side of the material inlet is a heating zone for drying and pyrolysis, and the remaining portion is a combustion zone for undecomposed residues and chars sent from the heating zone. In such a fluidized bed incinerator, steam and pyrolysis gas are generated from the heating zone, and combustion gas is generated from the combustion zone. In this case, the steam and pyrolysis gas, the combustion gas, The drift with the secondary combustion air blown out from the nozzle becomes remarkable, making it more difficult to mix them, and even in the secondary combustion chamber, many unburned components contained in the combustion gas are completely burned. Therefore, highly toxic dioxins are generated in the combustion exhaust gas by the dioxin precursor contained in the unburned matter. The dioxins are collected by the bag filter type dust collector together with other dust, but are not perfect, and it is desired to reduce the amount of generated dioxins due to the problem of post-treatment of collected ash.

An object of the present invention is to provide a fluidized bed incinerator capable of solving the above-mentioned problems and suppressing the remaining of unburned matters when incinerating municipal waste and industrial waste.

[0007]

SUMMARY OF THE INVENTION A fluidized bed incinerator according to the present invention has a primary combustion chamber at a lower portion of a furnace body.
In the fluidized bed incinerator in which a secondary combustion chamber is provided in the upper part, a throttle portion is provided between the primary combustion chamber and the secondary combustion chamber, and a fluidized bed is formed in the primary combustion chamber, The horizontal cross-sectional shape of the chamber is rectangular, and a longitudinal central portion at an upper portion of one of two opposing walls of the primary combustion chamber and a longitudinal direction at an upper portion of the other wall. At the center and both ends of the nozzles, nozzles for blowing out the secondary combustion air into the primary combustion chamber are provided, respectively.
The size of the tip outlet of the nozzle on the one wall is larger than that of the nozzle at the center in the longitudinal direction of the other wall.

According to the fluidized bed incinerator of the present invention, the horizontal cross section of the primary combustion chamber is rectangular, and the length of the primary combustion chamber at the upper part of one of the two opposing walls is long. A nozzle for blowing secondary combustion air into the primary combustion chamber is provided at each of the central portion in the longitudinal direction and the central portion and both ends in the longitudinal direction in the upper portion of the other wall, and the one wall is provided with the nozzle. Since the size of the tip outlet of the nozzle is larger than the tip outlet of the nozzle at the center in the length direction on the other wall, when the secondary combustion air is blown out from all the nozzles, The secondary combustion air blown out from the nozzle on the one wall travels as a thick flow toward the other wall, and the secondary combustion air blown out from the nozzle at the center in the longitudinal direction of the other wall. Is divided into two by a small flow of air Toward both ends in the longitudinal direction of the wall. Next, the air is advanced toward the one wall by the secondary combustion air blown out from the nozzles at both ends in the longitudinal direction of the other wall. Therefore, two large swirls are formed in the primary combustion chamber in combination with the fact that the horizontal sectional shape of the primary combustion chamber is rectangular, and the combustion gas and the secondary combustion air rising from the fluidized bed are formed. The stirring and mixing can be performed efficiently, and a part of the unburned portion in the combustion gas can be burned. When the fluidized bed is divided into a heating zone and a combustion zone, the steam and pyrolysis gas rising from the heating zone, the combustion gas rising from the combustion zone, and the secondary combustion air are separated from each other. The stirring and mixing can be performed efficiently, and a part of the pyrolysis gas and a part of the unburned portion in the combustion gas can be burned. In any case, the unburned portion is further combusted in the throttle section and the secondary combustion chamber subsequent to the primary combustion chamber, and as a result, compared with the conventional fluidized bed incinerator, the unburned portion containing the dioxin precursor is not burned. The amount of dioxins is reduced, and the generation of dioxins is prevented.

In the fluidized-bed incinerator according to the present invention, the narrow section has a rectangular horizontal cross-sectional shape, and a plurality of secondary combustion air blown into the narrow section by two opposite walls of the narrow section. Preferably, nozzles are provided, and all the nozzles are provided so as to be staggered as a whole when viewed from a plane. In this case, when the secondary combustion air is blown out from all the nozzles provided in the throttle section, the flow of the combustion gas and the secondary combustion air flowing into the throttle section from the primary combustion chamber, or steam, pyrolysis gas In addition, the flow of the combustion gas and the secondary combustion air is further disturbed, and the agitation and mixing of these and the agitation and mixing of these with the secondary combustion air blown out from the nozzle of the throttle portion are promoted, and the decomposition of the pyrolysis gas is promoted. A part and a part of the unburned portion in the combustion gas can be burned. Therefore, the final amount of unburned matter further decreases.

Further, in the fluidized bed incinerator according to the present invention, the horizontal cross section of the secondary combustion chamber is rectangular, and the two sections of the secondary combustion chamber are respectively provided below the two opposing walls of the secondary combustion chamber. A plurality of nozzles for blowing air for secondary combustion are provided, and the air blowing amount of a nozzle provided on one of the two walls and the air blowing amount of a nozzle provided on the other wall are provided. However, it is preferable to provide a means for alternately switching one of them so as to be large and the other to be small. in this case,
The collision position of the secondary combustion air blown out from the nozzle provided on the one wall and the nozzle provided on the other wall changes, and as a result, the combustion flowing into the secondary combustion chamber from the throttle portion. The flow of gas and secondary combustion air, or the flow of steam, pyrolysis gas, combustion gas, and secondary combustion air was further disturbed, and these were stirred and mixed together and discharged from the nozzle of the secondary combustion chamber. Agitation mixing with the next combustion air is promoted. Therefore, the remaining portion of the pyrolysis gas and the remaining portion of the unburned portion in the combustion gas can be burned, and the final amount of the unburned portion is drastically reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

In FIG. 1 to FIG. 4, a fluidized bed incinerator comprises:
A primary combustion chamber (2) is provided at the lower part of the furnace body (1), and a secondary combustion chamber (3) is provided at the upper part of the furnace body, and a throttle is provided between the primary combustion chamber (2) and the secondary combustion chamber (3). Section (4) is provided.

[0013] The primary combustion chamber (2) has a square horizontal cross section, and in the middle of the height of the front wall (2a), the incinerated material that sends municipal solid waste, industrial waste, etc. into the primary combustion chamber (2). Input port (5)
Are formed. Fluidized bed at the bottom of the primary combustion chamber (2)
(6) is formed. The front of the fluidized bed (6) is provided with a heating zone (7) for drying and pyrolyzing the incinerated material sent from the incinerated material inlet (5) by heating. The rear portion is provided with a combustion zone (8) for burning a mixture of undecomposed residue and char sent from the heating zone (7). In the heating zone (7) of the fluidized bed (6), a plurality of diffuser tubes (11) arranged on an inclined wall (9) that is inclined rearward and downward in the first half of the bottom wall of the primary combustion chamber (2). ), A fluidized bed is formed using a fluid medium such as sand. In the combustion zone (8) of the fluidized bed (6),
Sand and the like are formed by a plurality of air diffusers (13) formed in the latter half of the bottom wall of the primary combustion chamber (2) and disposed above the discharge port (12) for discharging ash, incombustibles and a part of the fluid medium. The fluidized bed is formed by using the fluidized medium. The fluid medium is in both zones
It circulates between (7) and (8). Both zones (7) (8)
The primary combustion air is supplied to the air diffusers (11) and (13). The supply amount of primary combustion air to both diffuser pipes (11) and (13) depends on the formation of a fluidized bed of a predetermined height in the fluidized bed (6) by the fluidized medium and the fluidized bed (6). 7) (8)
Is maintained at a predetermined temperature. The temperature in both zones (7) and (8) of the fluidized bed (6) depends on the size of the furnace and the quality of the incinerated material, but if the incinerated material is flammable, for example, containing a lot of paper and plastic, In order to prevent unstable combustion due to instantaneous decomposition or combustion, the temperatures of both zones (7) and (8) are set to 550 to 550.
Maintained at 650 ° C.

The primary combustion chamber has a central portion in the left-right direction at the upper end of the rear wall (2b) of the primary combustion chamber (2) and a central portion in the horizontal direction and both left and right ends of the upper end of the front wall (2a).
A nozzle (14) (hereinafter, referred to as a first nozzle) for blowing secondary combustion air is provided in (2). 1st of rear wall (2b)
The size of the tip outlet of the nozzle (14) is larger than the tip outlet of the first nozzle (14) at the center in the left-right direction on the front wall (2a). The first nozzle (14) on the front wall (2a) has a pipe for supplying air for primary combustion to both diffuser pipes (11) and (13).
Air is supplied through a pipe (16) branched from (15), and a dedicated first nozzle pipe is provided to the first nozzle (14) of the rear wall (2b).
Air is supplied through (17).

The horizontal cross-sectional shape of the throttle portion (4) is a rectangular shape that is long in the left-right direction, the length in the left-right direction is equal to the length in the left-right direction of the primary combustion chamber (2), and only the width in the front-rear direction is primary. It is smaller than the length of the combustion chamber (2) in the front-rear direction.
On the front and rear walls (4a) and (4b) of the diaphragm (4), respectively, the diaphragm (4)
A plurality of nozzles (18) that blow air for secondary combustion into
2nd nozzles) are provided at intervals in the left-right direction. All the second nozzles (18) are provided in a staggered arrangement as a whole when viewed from a plane. That is, the second nozzle (18) of the front wall (4a) is one less than the second nozzle (18) of the rear wall (4b), and is adjacent to the rear wall (4b) in the left-right direction. The second nozzles (18) are arranged so as to come to the middle part between the second nozzles (18). All the second nozzles (18) branch off from a first nozzle pipe (17) for supplying secondary combustion air to the first nozzles (14) on the rear wall (2b) of the primary combustion chamber (2). The secondary combustion air is supplied by the second nozzle pipe (21) that extends.

The secondary combustion chamber (3) has a square horizontal cross section, and the size of the horizontal cross section is equal to the size of the horizontal cross section of the primary combustion chamber (2). At the lower ends of the front and rear walls (3a) and (3b) of the secondary combustion chamber (3), a plurality of nozzles (22) (hereinafter, referred to as “blowers”) for blowing secondary combustion air into the secondary combustion chamber (3) are provided. Third
Nozzles) are provided at intervals in the left-right direction. The third nozzle (22) of the front wall (3a) and the third nozzle (22) of the rear wall (3b) face each other. All third nozzles (2
In (2), a third nozzle pipe (23) that branches off from a second nozzle pipe (21) that supplies air for secondary combustion to a second nozzle (18) of the throttle section (4) and extends. Secondary combustion air is supplied.

The third nozzle pipe (23) branches forward and backward on the way, and the front and rear branches (23a) and (23b) have front end portions respectively at the front and rear walls (3a) and (3b) of the third nozzle (22). And is connected to the third nozzle (22). In the portion where the third nozzle pipe (23) branches forward and backward, the air blowing amount of the third nozzle (22) of the front wall (3a) and the air of the third nozzle (22) of the rear wall (3b) are provided. An air blowout amount switching device (24) (switching means) is provided which alternately switches the blowout amount so that one is large and the other is small. The switching device (24) is disposed in the casing (26) in which air outlets (25) are formed at both left and right ends, and the casing (26),
A hollow cylindrical blowing amount adjusting member (27) having an axis extending in the front-rear direction and rotatable around the axis, both ends of which are closed. Branch portions (23a) (23b) are connected to both air outlets (25) of the casing (26), respectively. A motor (28) is provided on the outer surface of the left side wall of the casing (26).
The motor (28) is used to adjust the blowing amount adjustment member (2).
7) can be rotated. Blow-off amount adjustment member
A third end is connected to the right end wall of (27) via a rotary joint (29).
The nozzle pipe (23) is connected. In addition, two large and small air outlets (31) and (32) are formed on the peripheral wall of the blowout amount adjusting member (27) on one diameter. And the blowing amount adjusting member
When the large air outlet (31) of (27) faces rearward and the small air outlet (32) faces forward, the third nozzle (22) of the rear wall (3b)
Of the third nozzle (22) of the front wall (3a) is small. Further, when the blow-off amount adjusting member (27) is rotated by the motor (28) so that the large air outlet (31) faces forward and the small air outlet (32) faces rearward, the front wall (3a)
The air blowing amount of the third nozzle (22) is large, and the air blowing amount of the third nozzle (22) on the rear wall (3b) is small. Thus, the motor (2
When the direction of the air outlets (31) and (32) is changed by rotating the blow-out amount adjusting member (27) at predetermined intervals by 8), the third nozzle of the front wall (3a) as shown in FIG. (22) Air blowing volume and rear wall
The amount of air blown from the third nozzle (22) of (3b) is alternately switched so that one is large and the other is small.
The air blown out from the third nozzle (22) of (3a) and the rear wall (3b)
The collision position with the air blown from the third nozzle (22) changes.

The supply amount of the secondary combustion air to the first to third nozzles (14), (18) and (22) depends on the temperature at the outlet of the secondary combustion chamber (3).
From 0 to 950 ° C., O ₂ content is adjusted to be 6-9%.

In the fluidized bed incinerator having the above structure, the incinerated material is fed from the inlet (5) to the heating zone (7) of the fluidized bed (6) of the primary combustion chamber (2). In the heating zone (7), a fluidized bed is formed by the diffuser pipe (11) using the high-temperature fluidized medium returned from the combustion zone (8), and the incinerated material that is sent in is heated and dried. At the same time, the plastic therein is thermally decomposed. The pyrolysis gas and steam rise in the primary combustion chamber (2).

The mixture of the undecomposed residue and the char generated in the heating zone (7) is sent to a combustion zone (8) together with a fluidized medium, and is burned in a fluidized bed formed by a diffuser (13). The combustion gas rises in the primary combustion chamber (2). Part of the ash, incombustibles and fluidized medium is discharged from the outlet (12) to the outside of the furnace body (1), and only the fluidized medium is separated and returned to the fluidized bed (6) in the primary combustion chamber (2). It is.

When the secondary combustion air is blown out from all the first nozzles (14), the secondary combustion air blown out from the first nozzles (14) on the rear wall (2b) becomes a thick flow. Going forward, it is divided into two sides by the narrow flow of secondary combustion air blown out from the first nozzle (14) at the center of the front wall in the left-right direction, and the left and right side walls (2c) of the primary combustion chamber (2) Go to (2d) side. Next, the air is advanced toward the rear wall (2b) by the secondary combustion air blown out from the first nozzles (14) at the left and right ends of the front wall (2a). Therefore, two large swirls are formed in the upper part of the primary combustion chamber (2), and the steam, pyrolysis gas and combustion gas rising from the fluidized bed (6) and the two vortices blown out from the first nozzle (14). The air for the next combustion is efficiently stirred and mixed, and a part of the pyrolysis gas and a part of the unburned part in the combustion gas are burned.

The remainder of the steam, the pyrolysis gas, the combustion gas, and the balance of the secondary combustion air further rise and enter the throttling portion (4), and all the second nozzles (18) provided in the throttling portion (4). When the secondary combustion air is blown out of the primary combustion chamber (2), the flow of the steam, the remainder of the pyrolysis gas, the combustion gas and the remainder of the secondary combustion air flowing into the throttle (4) from the primary combustion chamber (2) is reduced. The mixture is further disturbed, and the stirring and mixing of these and the stirring and mixing of these with the secondary combustion air blown out from the second nozzle (18) are promoted. Some of it burns.

The remainder of the steam, the pyrolysis gas, the combustion gas, and the balance of the secondary combustion air further rise and rise in the secondary combustion chamber.
(3) Go inside. Here, while rotating the blow-out amount adjusting member (27) by a motor (28) every predetermined time to change the direction of the blow-out ports (31) and (32), the secondary combustion When air is blown out, the amount of air blown out of the third nozzle (22) on the front wall (3a) and the amount of air blown out of the third nozzle (22) on the rear wall (3b) are one large and the other small. And the air blown out from the third nozzle (22) of the front wall (3a),
The collision position with the air blown from the third nozzle (22) of the rear wall (3b) changes. As a result, the secondary combustion chamber
(3) The flow of steam, the remainder of the pyrolysis gas, the combustion gas and the remainder of the secondary combustion air that have flowed into
The stirring and mixing of these and the mixing with the secondary combustion air blown out from the third nozzle (22) are sufficiently performed. Therefore, the remainder of the pyrolysis gas and the remaining unburned portion in the combustion gas burn. In this way, complete combustion is promoted, the unburned components in the combustion gas containing the dioxin precursor are drastically reduced, and the generation of dioxin is prevented beforehand, and an exhaust gas with a very small or no dioxin content is released into the atmosphere. You.

In the above embodiment, the fluidized bed is divided into the heating zone and the combustion zone. However, the present invention is not limited to this, and the fluidized bed does not necessarily need to be divided into the heating zone and the combustion zone. Absent.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing one embodiment of a fluidized bed incinerator according to the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1;

FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG.

FIG. 5 is a graph showing a change in an amount of air blown from a third nozzle before and after a secondary combustion chamber.

[Explanation of symbols]

 (1): Furnace body (2): Primary combustion chamber (2a): Front wall (2b): Rear wall (3): Secondary combustion chamber (4): Restrictor (6): Fluidized bed (14): No. 1 nozzle

Continued on the front page (72) Inventor Tomohiro Aoki 5-3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Hitachi Zosen Corporation (72) Inventor Ken Matsui 5-28-28 Nishikujo, Konohana-ku, Osaka-shi Hitachi Zosen Corporation In-house (72) Inventor Morio Sugiura 5-28 Nishikujo, Konohana-ku, Osaka Hitachi Zosen Corporation

Claims (3)

[Claims] 1. A primary combustion chamber is provided at a lower portion of a furnace body, and a secondary combustion chamber is provided at an upper portion thereof. A throttle portion is provided between the primary combustion chamber and the secondary combustion chamber, and the primary combustion chamber flows into the primary combustion chamber. In a fluidized bed incinerator having a bed formed therein, a horizontal cross section of the primary combustion chamber is formed in a rectangular shape, and a longitudinal direction at an upper part of one of two opposing walls of the primary combustion chamber. A nozzle for blowing air for secondary combustion into the primary combustion chamber is provided at a central portion of the first wall and a central portion and both ends in the longitudinal direction of the upper portion of the other wall, respectively. The size of the tip outlet of
A fluidized bed incinerator which is made larger than the tip outlet of the nozzle at the center in the longitudinal direction of the other wall. 2. The throttle section has a rectangular horizontal cross-sectional shape, and a plurality of nozzles for blowing secondary combustion air into the throttle section are provided on two opposing walls of the throttle section, respectively. The fluidized bed incinerator according to claim 1, wherein the fluidized bed incinerators are provided so as to be staggered as a whole when viewed from a plane. 3. The secondary combustion chamber has a horizontal cross-sectional shape that is rectangular, and a plurality of secondary combustion air that blows air into the secondary combustion chamber is provided below two opposing walls of the secondary combustion chamber. A nozzle is provided, and the air blowing amount of the nozzle provided on one of the two walls and the air blowing amount of the nozzle provided on the other wall are one large and the other small. 3. A device according to claim 1, further comprising: means for alternately switching so that
The fluidized bed incinerator as described.