JP2967035B2 - Fluidized bed heat recovery apparatus and operation method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed heat recovery apparatus for incinerating industrial waste, municipal solid waste, coal and the like by forming a fluidized bed composed of sand particles and the like, and recovering heat generated thereby, and its operation. It is about the method.

[0002]

2. Description of the Related Art Conventionally, a fluidized bed heat recovery apparatus for forming a fluidized bed composed of sand particles on an air dispersion plate has been often used as an apparatus for recovering heat generated by incineration of industrial wastes.
This apparatus has the advantages that the mixing of the particles in the fluidized bed is extremely good, the temperature in the bed can be kept uniform, and that the particle layer has a large heat retention capability, so that it can be easily restarted. I have.

As such an apparatus, for example, Japanese Patent Application Laid-Open
Japanese Patent Publication No. 187001 discloses a configuration as shown in FIG.

In this apparatus, a mountain-shaped air distribution plate 92 is provided at the bottom of a furnace 90, and discharge air of a blower 91, that is, a fluidizing gas is blown upward from the air distribution plate 92, whereby sand is formed. A fluidized bed of particles is formed. Specifically, the gas injection speed at the left and right wings of the dispersion plate 92 is set to be higher than that at the center, and
Above the air dispersion plate 92, a reflective partition 93 having a shape facing the jetting direction of the fluidizing gas is provided.
For this reason, the sand particles form a fluidized bed that is vigorously blown up by the left and right wings, is reflected by the reflection partition 93, and sinks at the center.

For such a fluidized bed, an upper inlet 8 is provided.
When an object to be treated such as municipal solid waste is introduced into the central main combustion chamber 96 from 9, the object to be treated is burned while flowing together with the sand particles in the fluidized bed, and the incombustible material is discharged into the incombustible material outlet 98.
And carried out of the apparatus by the screw conveyor 99. In addition, some of the sand particles enter the heat recovery chamber 94 outside the reflection partition 93 and settle in the heat recovery chamber 94. A heat transfer tube 95 is provided in the heat recovery chamber 94, and the heat of the sand particles entering the heat recovery chamber 94 is recovered by the heat transfer tube 95. The sand that has settled in the heat recovery chamber 94 passes under the reflection partition 93 and returns to the main combustion chamber 96.

[0006] An air nozzle 100 is provided directly above the bottom surface of the heat recovery chamber 94, and air is injected from the air nozzle 100 toward the center (toward the main combustion chamber 96), so that the heat recovery chamber 94. The sand at the bottom is locally
It is pulled out to the 6th side to prevent sand clogging at the bottom.

[0007]

In the above apparatus, the sand particles in the heat recovery chamber 94 are not fluidized unlike the sand particles in the main combustion chamber 96, and the sedimentation is caused only by the own weight. Has become. Therefore, the behavior of the sand particles in the heat recovery chamber 94 varies greatly in place. For example, the sand particles move relatively actively in the vicinity of the reflection partition 3 and the air nozzle 100, but in other regions, particularly, In the vicinity of the side wall of the furnace 90, sand particles stay without hardly settling, and become a dead space that does not contribute to the improvement of the heat recovery rate at all. For this reason, the amount of heat absorption by the heat transfer tubes 95 varies greatly, and it is difficult to recover heat with high efficiency.

In this apparatus, there is no way to directly adjust the heat recovery rate in the heat recovery chamber 94. Depending on the operating conditions, the actual heat recovery rate may be much lower than the target heat recovery rate or, conversely, the target heat recovery rate. There is a possibility that the temperature and pressure of the heat recovery medium (for example, steam) in the heat transfer tube 95 may rise excessively if the rate is exceeded.

The above-described apparatus discloses an air nozzle 100 for forcibly blowing off sand particles at the bottom of the heat recovery chamber 94. The air nozzle 100 injects air in the horizontal direction, and the The flow of the sand particles is only locally formed at the bottom of the heat recovery chamber 94, and the sand particles cannot be smoothly lowered over substantially the entire area of the heat recovery chamber 94.

[0010] In view of such circumstances, the present invention provides a fluidized bed heat recovery apparatus capable of improving the heat recovery rate in the heat recovery section, and more preferably freely adjusting the heat recovery rate, and an operation method thereof. The purpose is to:

[0011]

The present inventors have repeatedly studied means for solving the above-mentioned problems, and as a result, if the sand particles in the heat recovery section are actively fluidized, the lowering of the sand particles will be smooth. It has been found that the heat recovery rate is greatly improved.

The present invention has been made as a result of such studies, and a fluidized bed formed of fluidized particles at the bottom of the apparatus main body is divided into a main combustion section and a heat recovery section by a baffle. A diffuser for injecting a fluidizing gas for raising and lowering the fluidized particles is provided at the bottom of the combustion section, a heat transfer tube for heat recovery is provided in the sub-fluidized bed, In a fluidized bed heat recovery device configured such that fluidized particles enter the heat recovery section through above the baffle, and further pass below the baffle and return into the main combustion section, at the bottom of the heat recovery section A sub-aerator is provided for injecting a fluidizing gas for fluidizing the fluidized particles in the heat recovery section (claim 1).

[0013] As the auxiliary air diffuser, a dispersing plate constituting a floor of the heat recovery section and having a plurality of gas injection ports, and gas injection means for injecting fluidizing gas from the gas injection ports of the distribution plate are provided. In addition, it is preferable that the dispersing plate is inclined in such a direction that the dispersing plate becomes lower as approaching the main combustion portion.

[0014] In this case, the inclination angle of the dispersion plate of the sub-aerator is set to 10 ° or more and 35 ° or less (claim 3), and more preferably 20 ° or more and 30 ° or less (claim 4). Good.

Further, the gas supply speed, which is the amount of fluidizing gas supplied per unit area per unit time from the sub diffuser to the heat recovery unit, is defined as the gas supply speed of the diffuser. It would be even more preferable to provide an adjusting means for changing independently.

The present invention also relates to a method for operating a fluidized-bed heat recovery apparatus according to any one of claims 1 to 5, wherein the gas supply speed by the sub-aerator is at least a minimum fluidization speed. The speed is set to be four times or less the minimum fluidization speed (claim 6).

In the fluidized-bed heat recovery apparatus according to a fifth aspect of the present invention, the operation of adjusting the gas supply speed by the sub-aperture device to a speed equal to or higher than the minimum fluidization speed and corresponding to the target heat transfer coefficient is performed. A method is possible (claim 7).

[0018]

According to the first aspect of the present invention, the fluidized particles in the heat recovery unit are fluidized by the fluidizing gas injected from the sub diffuser at the bottom of the heat recovery unit. Heat is smoothed over substantially the entire area of the heat recovery section, and the heat of the fluidized particles is uniformly and efficiently recovered by the heat transfer tube.

Here, the gas supply speed by the sub-aerator is not less than the minimum fluidization speed determined by the particle diameter and density of the fluidized particles and the density and viscosity of the fluidized gas. If the supply rate is increased to a certain extent, the heat recovery rate does not increase any more, and instead the microscopic speed of each fluidized particle may increase, which may promote abrasion damage of the heat transfer tube. More preferably, the gas supply speed is set to a speed of four times or less of the minimum fluidization speed.

Further, as described later, there is a correlation between the gas supply rate and the heat recovery rate. By providing the adjusting means for changing independently of the gas supply speed by the device, control such as adjusting the gas supply speed by the sub-aperture device so as to obtain the target heat transfer coefficient can be performed as described in claim 7. Will be possible.

According to the above-described apparatus and operating method,
Regardless of the specific structure of the auxiliary diffuser, the heat recovery rate is improved by fluidizing the fluidized particles in the heat recovery unit. A dispersion plate having a plurality of gas injection ports, which constitutes a floor of a heat recovery unit, and gas injection means for injecting a fluidizing gas from the gas injection holes of the distribution plate, and the dispersion plate is provided in the main combustion unit. The movement of the fluidized particles from the heat recovery unit to the main combustion unit can be promoted by inclining in a direction that becomes lower as the distance from the heat recovery unit decreases. To that extent, circulation of the flowing particles between the main combustion section and the heat recovery section is activated, and the heat recovery rate is further increased.

However, when the inclination angle reaches a certain degree, the heat recovery rate does not increase even if the inclination angle is further increased, and conversely, the fluidized bed of the heat recovery section on the side closer to the main combustion section by the larger inclination angle. The pressure of the fluidized gas is increased due to the weight of the fluidized bed. Therefore, the inclination angle is 10 ° or more and 35 ° as described in claim 3.
Hereinafter, it is more preferable that the angle is set to 20 ° or more and 30 ° or less.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

The fluidized-bed heat recovery apparatus shown here has a heat insulating wall 1
1 and a fluidized bed 12 made of sand or the like is formed at the bottom of the incinerator 10.
The free board 14 shown in FIG. An incineration material inlet 16 is formed in the middle part of the incinerator, to which an incineration material feeder 18 is connected, and secondary air blowers 20, 22 are also provided at appropriate heights in the middle part of the incinerator. And a duct 24 is connected to the upper part of the incinerator.

The heat insulating wall 11 of the free board 14 is
At a certain height, the inner surface has a membrane structure covered with a refractory material, and is configured to absorb heat from a gas layer through a wall surface. The vapor evaporated by the membrane is stored in the steam reservoir 2
5, and the steam recovers the heat of the exhaust gas by the super heater 26 and is sent to an inlet header 47 of a heat transfer tube 46 described later. After the exhaust gas is deprived of heat by the super heater 26, it is further evaporated by an evaporator 28 having the same structure as the membrane of the furnace wall, a feed water heater 29 for avoiding low-temperature corrosion, and an air heater 30 for combustion air. Deprived of heat. Then, after being cooled by the gas cooler 32, the dust is removed by the bag filter 34, and is exhausted from the chimney through the exhaust fan 36.

Next, the structure of the bottom of the incinerator 10 is shown in FIG.
A description will be given based on FIG.

At the center of the furnace bottom in the left-right direction, a first dispersion plate 38 is provided.
The second dispersion plate 40 is disposed on both left and right sides of the first dispersion plate 38, and both the second dispersion plates 40 are adjacent to the heat insulating wall (device body side wall) 11. First dispersion plate 38
And the second dispersion plate 40 are horizontally separated from each other, and this portion serves as an incombustible discharge portion 42. Below the incombustible discharge section 42, an incombustible extractor 44 is provided.
The incombustibles extraction device 44 is provided with the incombustibles discharge section 42.
It has a built-in screw conveyor that transports the sand containing incombustibles derived from the outside to both left and right sides.

Here, the first dispersion plate 38 is inclined in a mountain shape so as to become lower toward the left and right non-combustible material discharge portions 42, and the second dispersion plate 40 is also inclined toward the non-combustible material discharge portion 42. It is inclined in the direction of lowering. The preferred range of the inclination angle will be described later in detail.

Above both second dispersion plates 40, a plurality of heat transfer tubes 46 are arranged at equal intervals in the depth direction in FIG. 1 (the vertical direction in FIG. 2). Each heat transfer tube 46 penetrates the lower part of the heat insulating wall 11 to the side, faces the inside of the furnace, meanders on the second dispersion plate 40, and penetrates the heat insulating wall 11 above the penetrating part to the outside of the furnace. Both ends are connected to an inlet header 47 and an outlet header 48 extending in the depth direction of FIG. Then, the steam sent from the super heater 26 to the inlet header 47 flows through the heat transfer tube 46 as an incineration heat recovery medium, and is recovered by the outlet header 48.

In this furnace, a plurality of diffuser tubes 50 are provided as shown in FIG.
Are arranged side by side in the depth direction. Each diffuser tube 50 includes an upper portion 51 located above the heat transfer tube 46 and an upright portion extending from the upper portion 51 in a substantially vertical direction through the side of the heat transfer tube 46 to reach the second distribution plate 40. 52, a number of gas injection holes are formed in the side surface of the tube wall of the upper portion 51 and in the vicinity thereof.

The upper part 51 is inclined so as to become lower toward the incombustible discharge part 42, and the upper surface of the fluidized bed 12 is located slightly above the upper part 51.
The setting of the above-mentioned inclination angle is free, but specifically, it is preferably 5 ° or more and 35 ° or less.

A baffle 54 made of a refractory material, a jacket, or the like is provided around an intermediate portion of the upright portion 52. By the baffle 54, the fluidized bed 12 is divided into a central main combustion portion 12A and left and right outer heat recovery portions 12B, and the second distribution plate 40 forms a floor of the heat recovery portion 12B. The part is a diffuser plate of the auxiliary diffuser according to the present invention. A minute gap 55 is secured between the baffles 54, and sand particles can flow through the gap 55 slightly.

The distance between the diffuser tubes 50 is determined by the heat transfer tubes 4.
6 is set to be equal to the arrangement interval of the air diffusion tubes 5, but the air diffusion tubes 5 are larger than the heat transmission tubes 46 by the diameter of the air diffusion tubes 50.
The gaps between the heat transfer tubes 46 are smaller than the gaps between the heat transfer tubes 46. The gap between the air diffusers 50 is a baffle 54.
It is also smaller than the vertical distance between the first and second dispersion plates 40 (ie, the exit width of the heat recovery unit).

A number of fluidizing gas injection holes are formed in the dispersion plates 38 and 40, a plurality of gas chambers 41 b are provided below the first dispersion plate 38, and a plurality of gas chambers 41 b are provided below the second dispersion plate 40. Gas chambers 40a, 41, 40b, and 40c are provided side by side in the left-right direction. A primary air blower (gas injection means) 56, which is a fluidizing gas (here, air) supply source, is connected to each gas chamber via a pipe 57, and the fluidizing gas discharged from the primary air blower 56 is supplied thereto. The fluidizing gas is injected from the fluidizing gas injection port toward the fluidized bed 12 in the furnace.

A fluidizing gas is supplied into the air diffuser 50 from a specific gas chamber 41 of the gas chamber below the second dispersion plate 40 and close to the incombustible substance discharge portion 42. It has become so. Further, the fluidizing gas injected from the gas chamber 40a closer to the incombustible substance discharge section 42 than the gas chamber 41 through the fluidizing gas injection port is supplied to the incombustible substance discharge section 4.
2, and passes through the baffle 54 near the surface facing the first dispersion plate 38 side.

A valve (adjusting means) 56 for adjusting the flow rate of the fluidizing gas flowing in each pipe 57 is provided in the middle of the pipe 57 connected to each gas chamber. The amount of chemical gas (air) injected can be adjusted independently for each pipe 57.

In this embodiment, basically, of all the gas chambers, the amount of fluidizing gas injected from the gas chamber 41b near the incombustible substance discharge section 42 is set relatively large, and the first dispersion plate 38
The fluidizing gas injection amount from the gas chamber 41 located below the heat transfer tube 46 in the central portion of the chevron and the second dispersion plate 40 is set relatively small. For such an injection amount setting, as shown by a white arrow in FIG. 1, sand particles rise near the side of the baffle 54 on the main combustion portion side,
A flow is formed that overflows to the center side of the furnace and to the upper portion 51 side of the diffuser tube 50 and sinks.

The amount of gas injected from the gas chambers 40b and 40c (ie, the amount of gas injected by the sub-diffusing device) will be described later in detail.

Next, the operation of this device will be described.

First, wastes (objects to be treated) such as municipal solids introduced from the incinerated material inlet 16 fall into the main combustion section 12A (in the main combustion section) and burn. This main combustion part 12
In A, sand particles are formed by the fluidizing gas injected from the gas chamber 41b through the gas injection port of the first distribution plate 38 and the fluidizing gas injected from the gas chamber 40a through the gas injection port of the second distribution plate 40. The sand particles rising through the vicinity of the baffle 54 are repeatedly settling violently and rising and falling, respectively, overflowing to the center side of the furnace and the upper part 51 side of the diffuser 50 and settle.

More specifically, the particles overflowing to the upper portion 51 pass through the gap between the upper portions 51 and pass through the baffle 5.
After sinking between the heat transfer tubes 46 in the heat recovery portion 12B sandwiched between the heat transfer tube 4 and the heat insulating wall 11, the heat transfer tubes 46 are given incineration heat (that is, after the heat transfer tubes 46 collect the incineration heat). Then, it slides down along the inclined surface of the second dispersion plate 40 toward the non-combustible material discharge portion 42 side. Further, the particles overflowing to the center of the furnace settle as they are at the center of the chevron of the first dispersing plate 38, and the first dispersing plate 38
Along the inclined surface toward the incombustible discharge part 42 side. Here, the gas chamber 41 immediately before the incombustibles discharge section 42
Since a strong fluidizing gas is injected from b, some sand particles are pushed up by the fluidizing gas and recirculated to the main combustion section, and the other sand particles are mixed with noncombustibles (solids). It falls into the incombustible discharge part 42 and is carried out to the left and right outer sides by the incombustible substance extracting device 44. This discharge is sieved and only fine sand particles are resupplied to the fluidized bed 12.

Here, in the heat recovery section 12B,
Since the fluidizing gas is injected from the gas chambers 40b and 40c provided at the bottom through the injection port of the second dispersion plate 40, the injection amount of the fluidizing gas can be appropriately adjusted by operating the valve 53. If the amount is adjusted, the sand particles of the heat recovery unit 12B can be fluidized similarly to the sand particles of the main combustion unit 12A,
Thereby, the descent of the sand particles in the heat recovery unit 12B can be smoothed over substantially the entire area. Due to such a smooth drop of the sand particles, the variation of the heat recovery rate by the heat transfer tubes 46 can be significantly reduced, and the heat recovery rate can be greatly improved.

FIGS. 4 (a) and 4 (b) show data collected by experiments. FIG. 4 (a) shows the ratio of the actual gas supply speed u to the minimum fluidization speed umf in the heat recovery unit 12B. The relationship with the average descending speed of sand particles is shown in FIG.
Indicates the relationship between the above ratio and the heat transfer coefficient. Here, the minimum fluidization speed umf refers to the minimum gas supply speed u at which the sand particles in the heat recovery unit 12B can be fluidized, and these minimum fluidization speed umf and the gas supply speed u in the heat recovery unit 12B are: Is represented by the following equation.

[0044]

Umf = d _p ² (ρ _p −ρ _f ) g / 1650 μ u = Q / A where d _p is the sand particle diameter (mm) and ρ _p is the sand particle density (kg /
m ³ ), ρ _f is the fluidizing gas (air in this example) density (kg
/ m ³ ), μ is the fluidized gas viscosity (Pa · S), Q is the amount of gas injected by the heat recovery unit 12B per unit time, and A is the projected area in the gas injection direction of the heat recovery unit 12B (from above) Area seen)
It is.

As is clear from FIGS. 4A and 4B, the average descending speed and the heat transfer coefficient (a value corresponding to the heat recovery rate) of the sand particles in the heat recovery unit 12B are the same as the gas supply speed u. When the ratio with the fluidization speed umf reaches 1 (that is, when the gas supply speed u reaches the minimum fluidization speed umf), the ratio significantly increases, and becomes substantially constant when the ratio is 3 or more. On the other hand, if the gas supply speed u is set too high, the microscopic speed of the sand particles increases, and the heat transfer tube 46 is liable to wear and damage. Therefore, it is preferable that the actual gas supply speed u is set to a speed equal to or higher than the minimum fluidization speed umf and equal to or less than four times the minimum fluidization speed umf.

Further, as shown in FIG. 4B, there is a correlation between the above ratio and the heat transfer coefficient (between the above ratio and the heat recovery rate). Is adjusted so as to approach a gas supply speed corresponding to the target heat transfer coefficient, thereby enabling operation control to obtain a desired heat transfer coefficient. For example, a stable and preferable operation can be realized by detecting the temperature and the pressure of the steam flowing in the heat transfer tube 46 and adjusting the gas supply speed u so that the temperature and the pressure approach the target values.

Further, in this embodiment, since the second dispersion plate 40 is inclined in the direction of decreasing from the heat recovery section 12B toward the main combustion section 12A, the heat recovery section 12
B sand particles pass under the baffle 54 and pass through the main combustion section 12.
A can be promoted to return to the main combustion section 12A and the heat recovery section 12
It is possible to make the circulation of sand particles between B and B more active.

FIGS. 5 (a) and 5 (b) also show data collected by experiments. FIG. 5 (a) shows the relationship between the inclination angle of the second diffuser plate 40 and the average descending speed of sand particles. FIG.
Shows the relationship between the inclination angle and the pressure loss in the gas injection from the second diffuser plate 40.

As shown in FIG. 5A, the second diffuser plate 40
In the range where the inclination angle is about 25 ° or less, the average descending speed increases as the inclination angle increases, and in the range where the inclination angle exceeds 25 °, the average descending speed is substantially constant. On the other hand, in the heat recovery section 12B, the fluidized bed 1
Since it is necessary to embed the heat transfer tube 46 in the inside 2, the minimum depth of the fluidized bed 12 must be kept at a certain value or more, and in this relation, the inclination angle of the second diffuser plate 40 is large. Since the maximum depth of the fluidized bed 12 increases as the fluidized bed 12 becomes heavier, the greater the inclination angle of the second diffuser plate, the greater the pressure loss due to the weight of the fluidized bed 12 (see FIG. 2B). Therefore, in order to operate the device efficiently, the above-mentioned inclination angle is set to 1
It is better to set the angle in a range from 0 ° to 35 °, more preferably in a range from 20 ° to 30 °.

It should be noted that the present invention is not limited to this embodiment, and the following embodiments can be taken as examples.

(1) In the above embodiment, the first dispersing plate 38 is disposed at the center of the furnace, and the second dispersing plate 40 is disposed on both outer sides thereof. As shown in FIG. 7, a first dispersion plate 38 may be provided on one side of the furnace, a second dispersion plate 40 may be provided on the other side, and an incombustible substance discharge portion 42 may be provided substantially at the center of the furnace. In the first embodiment, the first distribution plate 38 and the second distribution plate 40 are linearly extended in the depth direction of FIG. 1, and the heat transfer pipe 46 and the air diffusion pipe 50 are extended along this direction.
As shown in FIGS. 8 and 9 as a third embodiment, as shown in FIGS. 8 and 9, a furnace has a cylindrical shape, and a conical first dispersion plate 38 is disposed in the center, and the A donut-shaped second dispersion plate 40 may be arranged on the outside, and an incombustible discharge portion 42 may be formed between the dispersion plates 38 and 40 over the entire circumference. In this case, the heat transfer tube 46 and the air diffuser tube 50 may also be provided side by side in the circumferential direction.

(2) In the above embodiment, the inlet header 47 and the outlet header 48 are arranged on both left and right outer sides of the furnace, and both ends of the heat transfer tube 46 are penetrated through the heat insulating wall (side wall) 11. As shown in FIGS. 10 and 11, as a fourth embodiment, a heat transfer tube 46 is passed in a straight line parallel to the heat insulating wall 11, and one end thereof is connected to an inlet header (not shown), and the other end is connected to an outlet header 48, respectively. You may make it. In this case, the arrangement direction of the heat transfer tubes 46 may be a vertical and horizontal direction as shown in FIG. 10 or an oblique direction as shown in FIG.

(3) The structure of the baffle in the present invention is not particularly limited, and the fluidized bed 12 is composed of the main combustion section 12A and the heat recovery section 12B.
Any material can be used as long as the fluidized particles can move above and below it. For example, a device in which the entire baffle is integrally formed of a single plate may be specially provided. In this case, a column different from the diffuser tube 50 may be erected on the second dispersion plate 40, and the column may be supported by the column. In the present invention, the air diffuser 5 is not necessarily used.
0 is not required.

(4) In the above embodiment, the two dispersion plates 38, 40
In the fifth embodiment, as shown in FIG. 13, a non-combustible discharge portion 42 is provided at the center of the furnace, and a first dispersion plate 38 and a second dispersion plate 40 are provided. The above heat recovery is possible even if the heat recovery is continued. In this case, if the gas injection amount from the first dispersing plate 38 is increased nearer to the incombustible discharge portion 42 as in the first embodiment, both dispersing plates 38, 4
0, a good reflux of the fluidized bed 12 can be formed.

Further, it is not necessary for each dispersion plate to be a continuous plane. As shown in FIG. 14 as a sixth embodiment, the central portion 38a of the mountain-shaped first dispersion plate 38 shown in the first embodiment is used.
May be made higher than both side portions 38b to form a step.

(5) In each of the above embodiments, the diffuser for injecting the fluidizing gas from the furnace bottom is constituted by the dispersing plates 38 and 40 and the means for injecting the gas from these dispersing plates 38 and 40. However, instead of the first dispersion plate 38, a diffuser tube 38 'as shown in FIGS. 15 and 16 may be provided as a seventh embodiment. In this embodiment, a plurality of diffuser tubes 38 'are arranged horizontally in parallel with each other, and a number of gas injection holes are formed in the upper half of each diffuser tube 38'.
'Are connected to a common entrance header 58 at one end. In this device, each diffuser 38 ′ is extended from each inlet header 58.
By supplying a fluidizing gas into the inside and injecting the gas upward from the gas injection holes of each diffuser tube 38 ′, a reflux can be formed in the fluidized bed 12. In this case, the incombustibles fall from the gaps between the diffuser pipes 38 ′, and the lower part of the diffuser pipes 38 ′ serves as the incombustible discharge section 42.

[0057]

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

According to a first aspect of the present invention, in the fluidized bed heat recovery apparatus, the fluidized bed is divided into a main combustion section and a heat recovery section.
A sub diffuser is provided at the bottom of the heat recovery unit, and the fluidized particles in the heat recovery unit are fluidized by a fluidizing gas injected from the sub diffuser,
In comparison with the conventional device in which the flowing particles settled only by their own weight in the heat recovery section, the descending of the flowing particles can be made uniform throughout,
There is an effect that the heat recovery rate through the heat transfer tube of the heat recovery unit can be greatly improved.

According to a sixth aspect of the present invention, in the above-mentioned apparatus, the gas supply speed by the sub-aerator is set to a speed not less than the minimum fluidization speed and not more than four times the minimum fluidization speed. Therefore, there is an effect that a high heat recovery rate can be secured while avoiding abrasion damage of the heat transfer tube.

Further, the apparatus according to the fifth aspect is provided with an adjusting means for changing the gas supply speed of the auxiliary air diffuser independently of the gas supply speed of the air diffuser. As described in 7, it is possible to perform control such as adjusting the gas supply speed by the sub-aperture device so as to obtain the target heat transfer coefficient. With such control, it is possible to freely obtain a desired heat transfer coefficient. There is an effect that can be done.

Further, in the apparatus according to the present invention, as the sub-aperture device, a floor of the heat recovery section is formed, and a dispersion plate having a plurality of gas injection ports, and a flow from the gas injection ports of the dispersion plate. Gas injecting means for injecting activated gas,
Since the dispersion plate is inclined in a direction that becomes lower as approaching the main combustion section, the movement of the flowing particles from the heat recovery section to the main combustion section is promoted, so that the main combustion section and the heat recovery section Thus, the circulation of the fluidized particles can be more activated, and the heat recovery rate can be further improved.

Here, in the apparatus according to the third aspect, since the inclination angle is set to 10 ° or more and 35 ° or less, a high heat recovery rate can be obtained while performing an efficient operation with a reduced pressure loss. There is an effect that can be secured. In particular, when the inclination angle is set to be not less than 20 ° and not more than 30 ° as described in claim 4, the above effect can be more remarkable.

[Brief description of the drawings]

FIG. 1 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional plan view showing the main part.

FIG. 3 is an overall configuration diagram of the fluidized bed heat recovery device.

FIG. 4A is a graph showing the relationship between the ratio of the gas supply speed to the minimum fluidization speed in the heat recovery section of the fluidized bed heat recovery device and the average sand particle falling speed, and FIG. It is a graph which shows the relationship with a heat transfer coefficient.

FIG. 5A is a graph showing a relationship between an inclination angle of a second dispersion plate and an average descending speed of sand particles in a heat recovery unit.
(B) is a graph showing the relationship between the inclination angle and the pressure loss of the air injection from the second dispersion plate.

FIG. 6 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a second embodiment of the present invention.

FIG. 7 is a partial sectional plan view showing the main part.

FIG. 8 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a third embodiment of the present invention.

FIG. 9 is a partial cross-sectional plan view showing the main part.

FIG. 10 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a fourth embodiment of the present invention.

FIG. 11 is a partial sectional plan view showing the main part.

FIG. 12 is a sectional front view showing a modification of the main part.

FIG. 13 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a fifth embodiment of the present invention.

FIG. 14 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a sixth embodiment of the present invention.

FIG. 15 is a sectional front view showing a main part of a fluidized bed heat recovery device according to a seventh embodiment of the present invention.

FIG. 16 is a sectional plan view showing a main part of the fluidized bed heat recovery device.

FIG. 17 is a sectional front view showing an example of a conventional fluidized bed heat recovery device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Incinerator 12 Fluidized bed 12A Main combustion part 12B Heat recovery part 38 1st dispersion plate (constituting a diffuser) 40 2nd dispersion plate (dispersion plate of an auxiliary diffuser) 40a, 41, 41a Gas chamber (aeration) 40b, 40c Gas chamber (gas injecting means of sub diffuser) 46 Heat transfer tube 53 Valve (adjusting means) 54 Baffle 56 Primary air blower (gas injecting means) 57 Pipe (gas injecting means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F23G 5/30 F23G 5/46

Claims (7)

(57) [Claims] 1. A fluidized bed formed of fluidized particles at the bottom of an apparatus body is divided into a main combustion section and a heat recovery section by a baffle, and the fluidized particles are moved up and down at the bottom of the main combustion section. A diffuser for injecting fluidized gas is provided, and a heat transfer tube for heat recovery is provided in the sub-fluidized bed, and the flowing particles of the main combustion section pass above the baffle to the heat recovery section. In the fluidized-bed heat recovery device configured to enter and return below the baffle to the inside of the main combustion section, a fluid for fluidizing fluidized particles in the heat recovery section is provided at a bottom of the heat recovery section. A fluidized bed heat recovery device, comprising a sub-aerator for injecting a gasification gas. 2. The fluidized bed heat recovery apparatus according to claim 1, wherein the auxiliary diffuser includes a dispersion plate having a floor of the heat recovery unit, the dispersion plate having a plurality of gas injection ports, and a gas of the dispersion plate. A fluidized bed heat recovery apparatus, comprising: gas injection means for injecting a fluidizing gas from an injection port, and wherein the dispersion plate is inclined in a direction to become lower as approaching the main combustion portion. 3. The fluidized-bed heat recovery apparatus according to claim 2, wherein the inclination angle of the dispersion plate of the sub-aerator is 10 ° or more.
A fluidized bed heat recovery device, wherein the temperature is set to 5 ° or less. 4. The fluidized-bed heat recovery apparatus according to claim 3, wherein the inclination angle of the dispersion plate of the sub-aerator is 20 ° or more.
A fluidized bed heat recovery device, wherein the temperature is set to 0 ° or less. 5. The fluidized bed heat recovery apparatus according to claim 1, wherein fluidization is supplied from the sub-aperture unit to the heat recovery unit per unit time per unit projected area. A fluidized bed heat recovery device comprising an adjusting means for changing a gas supply speed, which is a gas amount, independently of a gas supply speed by the air diffuser. 6. The method for operating a fluidized-bed heat recovery apparatus according to claim 1, wherein a gas supply speed of the sub-aeration device is equal to or higher than a minimum fluidization speed. A method for operating a fluidized-bed heat recovery device, wherein the speed is set to four times or less of the minimum fluidization speed. 7. The method for operating a fluidized-bed heat recovery device according to claim 5, wherein the gas supply speed by the sub-aerator is:
A method for operating a fluidized bed heat recovery apparatus, wherein the speed is adjusted to a speed higher than a minimum fluidization speed and corresponding to a target heat transfer coefficient.