JPH09112862A - Fluid bed type combustion device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To prevent incineration ash from adhering to a wall surface. SOLUTION: The combustion device main body 21 is formed in a cylindrical shape, and the secondary air nozzles 38 are unified and connected to the combustion device main body 21 in a tangential direction so that the combustion device main body 21 receives the secondary air. By forming the swirl upward flow of a and connecting the fluidized medium inlet 28 to the combustion apparatus main body 21 at the same height as the connection position 42 of the secondary air nozzle 38 or at a position above it. A part of the fluidized medium b circulated from the fluidized medium inlet 28 to the main body 21 of the combustion apparatus is entrained in the swirl upward flow, whereby the wall surface is cleaned by the fluidized medium b.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluidized bed combustion apparatus.

[0002]

2. Description of the Related Art A fluidized bed type combustion apparatus such as a waste incinerator generally puts municipal waste or other waste into a combustion apparatus body and burns it.

3 and 4 show a conventional fluidized bed type combustion apparatus.

In the figure, reference numeral 1 designates a substantially rectangular tube-shaped combustion device body having a waste supply port 2 formed in an intermediate portion and a hopper portion 3 formed in a lower portion, and 4 an upper portion of the hopper portion 3 of the combustion device body 1. A plurality of horizontal air diffusers arranged at intervals in the fluidized bed are formed of a fluidized medium such as fluidized sand and fluidized by primary air ejected from the air diffuser 4, and 6 is a main body of the combustion apparatus. 1 is a burner attached to the upper surface of the fluidized bed 5 in FIG.

7 is a fluid medium outlet provided at the lower end of the hopper 3, 8 is a fluid medium inlet formed near the upper surface of the fluidized bed 5 in the main body 1 of the combustion apparatus, 9 is fluid medium outlet 7 and fluid medium inlet 8 A fluid medium circulation path such as a bucket conveyor that connects the fluid medium circulation path 10 and the fluid medium circulation passage 10 is provided on the inlet side of the fluid medium circulation path 9, and 11 is a fluid medium conveyor 10.
It is a sieving device provided on the outlet side.

Further, 12 is a gas outlet for discharging the combustion gas 13 generated in the combustion apparatus main body 1 to the outside, 14 is an air supply passage connected to an external fan 15, and 16 is an air supply passage 14 A primary air supply passage 17 for supplying primary air to the air diffusing pipe 4, and a secondary air nozzle 17 for a secondary air nozzle 18 provided at a plurality of locations in the middle portion of the combustion apparatus main body 1, branched from the air supply passage 14. A secondary air supply passage adapted to supply air in a distributed manner, 19 is a secondary combustion zone formed in the upper part of the combustion apparatus main body 1, and 20 is a valve provided in the middle of the primary air supply passage 16.

Then, the air blower 15 is operated, and the combustion apparatus main body 1 is passed through the air supply passage 14 and the primary air supply passage 16.
By supplying primary air to the air diffuser 4 of the fluidized bed 5
The burner 6 and the combustion device body 1 by the burner 6.
The fluidized bed 5 therein is preheated, and in this state, the waste is introduced from the waste supply port 2 into the combustion apparatus main body 1.

Then, the waste material charged into the combustion apparatus main body 1 is thermally decomposed in the preheated fluidized bed 5 to generate combustible gas. The combustible gas generated by the thermal decomposition of the waste rises in the combustion apparatus main body 1 and is supplied in the secondary combustion zone 19 through the secondary air supply passage 17 and the plurality of secondary air nozzles 18 in the middle. Completely burned by the secondary air
It is discharged from the combustion gas discharge port 12.

Further, apart from the above, in the combustion apparatus main body 1,
A part of the fluidized medium constituting the fluidized bed 5 is sent from the fluidized medium outlet 7 at the lower end of the hopper section 3 to the sieving apparatus 11 via the fluidized medium conveyor 10, and after the incombustibles are removed by the sieving apparatus 11, It is returned from the fluidized medium inlet 8 to the combustion apparatus main body 1 via the fluidized medium circulation path 9, the combustion apparatus main body 1 is dropped as it is, and merged with the fluidized bed 5.

[0010]

However, the above fluidized bed combustion apparatus has the following problems.

That is, when low-melting substances such as glass are contained in municipal waste and other wastes, combustion ash containing the low-melting substances is raised together with combustible gas, and There is a problem that it adheres to the wall surface of the secondary combustion zone 19 where the temperature becomes highest.

Then, when the accumulation of the combustion ash on the wall surface has progressed to a certain extent, the operation of the fluidized bed combustion apparatus must be stopped and the operation of dropping the combustion ash must be performed each time, which leads to stable operation. It becomes an obstacle.

In view of the above situation, it is an object of the present invention to provide a fluidized bed combustion apparatus capable of preventing the incineration ash from adhering to the wall surface.

[0014]

According to the present invention, the outer shape of a combustion apparatus body having a fluidized bed formed in the lower portion is formed into a cylindrical shape, and a secondary air a is tangentially directed to an intermediate portion of the combustion apparatus body. The secondary air nozzle to be supplied is connected, and further, the fluid medium inlet for returning the fluid medium b extracted from the lower portion of the combustion device body to the intermediate portion of the combustion device body is connected to the combustion device body at the connection position of the secondary air nozzle. The fluidized bed combustor is characterized in that it is connected at the same height as or above.

In this case, the fluidized medium inlet may be arranged near the secondary air nozzle and in a tangential direction.

According to the above means, the following effects can be obtained.

The lower fluidized bed in the main body of the combustion apparatus is preheated and fluidized, and when the waste is put into the main body of the combustion apparatus in this state, the waste is thermally decomposed by the heat of the fluidized bed and combustible gas is discharged. Is generated. The combustible gas generated by the thermal decomposition of waste rises in the main body of the combustion device,
On the way, complete combustion is performed by the secondary air supplied through the secondary air nozzle.

Separately from the above, in the main body of the combustion apparatus, a part of the fluid medium constituting the fluidized bed is extracted and circulated from the fluid medium inlet to the main body of the combustion apparatus.

Further, in the present invention, the combustion apparatus main body is formed in a cylindrical shape, and the secondary air nozzle is unified so as to be connected tangentially to the combustion apparatus main body. A strong swirl upward flow of secondary air is formed at the.

The swirl upward flow promotes the mixing of the combustible gas and the secondary air. In addition, the swirling ensures a sufficient retention time of the combustible gas inside the main body of the combustion apparatus.

As a result, the combustibility of the combustible gas is improved as compared with the conventional one, and the generation of harmful substances such as dioxins due to incomplete combustion is suppressed.

Further, since the fluidized medium inlet is connected to the combustion apparatus main body at the same height as or above the connection position of the secondary air nozzle, the fluidized medium inlet is connected to the combustion apparatus main body. Part of the fluidized medium circulated to the swirl upward flow is entrained in the swirl upward flow and is lifted along the wall surface of the combustion apparatus main body by centrifugal force, and is separated from the swirl upward flow when the flow velocity of the swirl upward flow decreases. Since it comes down along the wall surface, the wall surface is cleaned by the fluidized medium.

Thus, even if the waste material such as municipal waste contains low melting point substances such as glass, the combustion ash is prevented from adhering to the wall surface, and the operation is performed in order to remove the combustion ash. There is no need to stop, and stable operation can be performed.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an example of the embodiment of the present invention.

In the figure, reference numeral 21 denotes a main body of a combustion apparatus in which a waste supply port 22 is formed in an intermediate portion, and a hopper portion 23 is formed in a lower portion, and 24 is provided above the hopper portion 23 of the main body 21 of the combustion apparatus with a space. A plurality of horizontal air diffusers arranged, 25 is a fluidized bed formed of a fluidized medium b such as fluidized sand, and fluidized by primary air ejected from the air diffuser 24, and 26 is a fluidized bed in the main body 21 of the combustion apparatus. 25 is a burner attached to the upper surface of 25.

27 is a fluid medium outlet provided at the lower end of the hopper 23, 28 is a fluid medium inlet formed in the main body 21 of the combustion apparatus, 29 is a fluid medium outlet 27 and fluid medium inlet 28.
A fluid medium circulation path such as a bucket conveyor that connects the fluid medium circulation path 30 and the fluid medium circulation path 30, a fluid medium conveyor 30 provided at the inlet side of the fluid medium circulation path 29, and a sieve device 31 provided at the fluid medium conveyor 30 outlet side.

Reference numeral 32 is a gas discharge port for discharging the combustion gas 33 generated in the combustion apparatus main body 21 to the outside, and 34
Is an air supply path connected to an external fan 35, 36 is a branch from the air supply path 34, is a primary air supply path for supplying primary air to the air diffuser 24, and 37 is a branch from the air supply path 34, A secondary air supply path adapted to disperse and supply the secondary air a to the secondary air nozzle 38 provided in the middle part of the apparatus body 21, 39 is a secondary combustion zone formed in the upper part of the combustion apparatus body 21. 40, 41 are primary air supply passages 36
And valves provided in the middle of the secondary air supply passage 37.

In the present invention, the combustion device main body 21 is formed in a cylindrical shape, the secondary air nozzle 38 is unified, and is connected tangentially to the combustion device main body 21, and the fluidized medium inlet 28 is further provided. With respect to the main body 21 of the combustion device, the secondary air nozzle 38 is connected at the same height as the connection position 42 or at a position above the connection position 42.

The fluidized medium inlet 28 may be arranged at an appropriate position and in an appropriate direction with respect to the circumferential direction of the combustion apparatus main body 21, as shown by a solid line in FIG. It is preferable to arrange in the vicinity of the secondary air nozzle 38 and in the tangential direction, as shown in FIG.

Next, the operation will be described.

By operating the blower 35 to supply the primary air to the air diffuser pipe 24 of the combustion apparatus main body 21 through the air supply passage 34 and the primary air supply passage 36, the fluidized bed 25 is fluidized and the burner is burned. 26 by the combustion device body 2
The fluidized bed 25 in 1 is preheated, and in this state, the waste is introduced from the waste supply port 22 into the combustion apparatus main body 21.

Then, the waste material charged into the combustion apparatus main body 21 is thermally decomposed in the preheated fluidized bed 25 to generate combustible gas. The combustible gas generated by the thermal decomposition of the waste rises in the combustion device main body 21 and, in the middle of the secondary combustion region 39, the secondary air supply passage 37 and the secondary air nozzle 3
Completely burned by the secondary air a supplied through
It is discharged from the combustion gas discharge port 32.

Separately from the above, in the combustion apparatus main body 21, a part of the fluidized medium b constituting the fluidized bed 25 is discharged from the fluidized medium outlet 27 at the lower end of the hopper portion 23 to the fluidized medium conveyor 3
0 to the sieving apparatus 31, the incombustibles are removed by the sieving apparatus 31, and the sieving apparatus 31 circulates the fluidized medium circulating passage 29 to the fluidized medium inlet 28 to the combustion apparatus main body 21.

In the present invention, the combustion device main body 21 is formed in a cylindrical shape, and the secondary air nozzle 38 is unified so that it is connected to the combustion device main body 21 in the tangential direction. A strong swirl upward flow of the secondary air a is formed in the secondary combustion zone 39 of the main body 21 of the combustion apparatus.

The swirl upward flow promotes the mixing of the combustible gas and the secondary air a. Further, the swirling ensures a sufficient retention time of the combustible gas inside the combustion device main body 21.

As a result, the combustibility of the combustible gas is improved as compared with the conventional one, and the generation of harmful substances such as dioxins due to incomplete combustion is suppressed.

Further, the fluidized medium inlet 28 is connected to the combustion apparatus main body 2
1, the secondary air nozzle 38 is connected at the same height as the connection position 42 of the secondary air nozzle 38 or at a position higher than the connection position 42. Therefore, the combustion device main body 21 from the fluid medium inlet 28 via the fluid medium circulation path 29. A part of the fluidized medium b circulated to the secondary combustion zone 3 is entrained in the swirl upward flow and is centrifugally generated.
9 rises along the wall surface, and when the flow velocity of the swirl upward flow decreases, it is separated from the swirl upward flow and descends along the wall surface, so that the flow medium b cleans the wall surface.

As a result, even if the municipal waste or other waste contains low-melting substances such as glass, the combustion ash is prevented from adhering to the wall surface, and the operation is carried out to remove the combustion ash. There is no need to stop, and stable operation can be performed.

Further, solid unburned components such as char formed by thermal decomposition of waste in the fluidized bed 25 rise together with the combustible gas, but the solid unburned components raised by being accompanied by the combustible gas rise as above. When the flow velocity of the swirl upward flow of the combustible gas is reduced in the upper part of the combustion device main body 21 due to the flow, it is separated from the combustible gas, descends by its own weight, and is again entrained in the high swirl upward flow of the upstream flow velocity. As it rises, it is circulated inside the combustion device main body 21, thereby forming an internal circulation flow of solid unburned components in the combustion device main body 21.

By this internal circulating flow, the residence time of the solid unburned material in the furnace is sufficiently lengthened, so that the combustion state of the solid unburned material is improved.

Moreover, due to the centrifugal force of the swirling upward flow, the solid unburned components gather along the wall surface of the main body 21 of the combustion apparatus, and in the solid unburned high concentration particle group thus formed along the inner wall, The powder and granular material blown up by the swirling upward flow separates the surface of the solid unburned matter so that a new surface always appears, so that the combustion of the solid unburned matter is promoted.

If the fluidized medium inlet 28 is arranged in the vicinity of the secondary air nozzle 38 and in the tangential direction, as shown by the phantom line in FIG. It becomes possible to secure a large amount of the medium b.

The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0045]

As described above, according to the fluidized bed combustion apparatus of the present invention, the excellent effect of preventing the incineration ash from adhering to the wall surface can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of an example of an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a schematic side sectional view of a conventional example.

4 is a view taken in the direction of arrows IV-IV in FIG. 3;

[Explanation of symbols]

 21 Combustion device body 25 Fluidized bed 28 Fluidized medium inlet 38 Secondary air nozzle 42 Connection position a Secondary air b Fluidized medium

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F23C 11/02 312 F23C 11/02 312 F23G 5/14 ZAB F23G 5/14 ZABF

Claims (2)

[Claims] 1. A combustion apparatus main body having a fluidized bed formed in a lower portion is configured to have a cylindrical outer shape, and a secondary air nozzle for supplying secondary air in a tangential direction is connected to an intermediate portion of the combustion apparatus main body. In addition, the fluid medium inlet for returning the fluid medium extracted from the lower part of the combustion device body to the intermediate part of the combustion device body is at the same height as the connection position of the secondary air nozzle with respect to the combustion device body, or above it. A fluidized bed combustor characterized by being connected in position. 2. The fluidized bed combustor according to claim 1, wherein the fluidized medium inlet is arranged near the secondary air nozzle and in a tangential direction.