JP3163547B2 - Swirling sand bed type fluidized-bed furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the improvement of a fluidized-bed furnace used for incineration of municipal solid waste and industrial waste. The present invention relates to a fluidized-bed furnace having a cyclone swirl sand layer that can be incinerated smoothly.

[0002]

2. Description of the Related Art Municipal refuse, industrial waste, and the like are generally incinerated using a step-type stoker furnace or a bubbling fluidized-bed furnace. However, recent refuse contains a large amount of high-calorie and low-specific-gravity substances such as paper and plastic films, so that the burning rate is inevitably increased. As a result, when incinerating garbage in a stoker furnace, the ash layer on the stoker sharply decreases, making it difficult to form an ash layer of an appropriate thickness, and as a result, troubles such as burning of the grate occur frequently. Tend to.

[0003] Further, when such wastes are incinerated in a bubbling fluidized-bed furnace, the proportion of light-weight substances floating and burning in the freeboard portion increases, and the amount of burned substances in the fluidized sand layer decreases. As a result, it becomes difficult to maintain the fluidized bed temperature at a predetermined temperature, and it becomes difficult to operate the furnace stably. still,
Since the inside of refuse and the like still contains not only lightweight materials but also relatively heavy combustible materials and incombustible materials, it is impossible to make a complete floating combustion furnace. Further, in the conventional bubbling type fluidized furnace, it is necessary to provide a large number of nozzles for flowing air at the bottom of the furnace. Generally, the nozzle is mounted on a plate-like structure forming the bottom, or The structure is such that nozzles are attached to many headers arranged at the bottom. As a result, incombustibles in the furnace are discharged to the outside of the furnace together with the sand through the removal holes formed in the plate-like structure or through the gap between the headers, and the size of the port is fixed. As a result, clogging of incombustibles tends to occur, and the furnace bottom often needs to be cleaned. Therefore, preliminary crushing of the refuse to be introduced into the furnace is required, and it is difficult to reduce the processing cost.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional bubbling fluidized-bed incinerator for incineration, namely, it is difficult to achieve stable fluidized combustion of the incinerated waste, and the incombustibles are smoothly moved out of the incinerator. It is intended to solve problems such as difficulty in discharging to the garbage, even if the garbage contains a large amount of high-calorie and light-weight substances, or garbage containing substances of various external dimensions, An object of the present invention is to provide a swirling sand bed type fluidized bed furnace which can be incinerated in an extremely stable state and can discharge incombustibles smoothly from the furnace bottom.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a furnace body having a freeboard portion, a swirling sand layer portion, a stationary sand layer portion, and an incombustible material take-out portion; and a plurality of steps on the outer periphery of the cylindrical swirling sand layer portion. , And supplies air in a substantially horizontal and tangential direction from a plurality of locations in each stage, and gradually reduces the diameter of the swirling sand layer from the upper stage to the lower stage. A swirling / incineration air blowing nozzle for forming a flow is a basic configuration of the present invention.

[0006]

[Action] Air flow C ₁ from the nozzle 20, by the air flow C ₂ is blown respectively from the airflow C ₂ and the nozzle 14 from the nozzle 22a, the inner rotation sand portion 2 of the furnace body A,
A swirling fluidized sand layer and sand F
Are formed respectively. Garbage supply port 16 such as garbage E
Is supplied into the furnace main body A by the fixed amount feeder 12 through the refuse, and most of the refuse is received into the swirling sand layer portion 2 where it is swirled and burned. In addition, the extremely lightweight combustible waste and the ash partially burned in the swirling sand layer portion 2 are suspended and burned in the freeboard portion 1. On the other hand, the sand F and the incombustibles in the furnace main body A are appropriately discharged out of the furnace through the sealing device 7 of the incombustibles take-out section 4 and separated into the sand F and the incombustibles Eb by the vibrating sieve 8. The separated sand F is returned to the sand silo 9 by the conveyor 13 and the sand fixed feeder 1
Through the sand supply port 15 provided above the swirling sand layer portion 3 through the rotary shaft 0, the sand is re-sent into the furnace main body 1.

[0007] Within swivel sand layer unit 2, an airflow C _1, a plurality of stages of whirling air current is formed sequentially reduced in diameter toward downward from above, thereby swirling fluidized sand is produced.
In addition, the air at the outer peripheral portion of the upper end of the stationary sand layer portion 3 is actively bubbled and flown by the airflow C ₂ from the nozzle 22a, and the sand is supplied into the upper turning sand layer portion 2. Furthermore,
The flow of sand by the air flow C _2, incombustibles Eb is transferred to the central portion of the stationary sand layer portion 3. The form of the mortar-shaped furnace bottom formed by the stationary sand layer is changed by adjusting the discharge amount of the sand F from the incombustible material take-out part 4, whereby the flow of the incombustible material Eb discharged out of the furnace together with the sand is reduced. , Become more smooth.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of a fluidized-bed furnace according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a longitudinal sectional view taken along line BB of FIG. In the figure, A is a furnace main body, 1 is a freeboard section, 2 is a swirling sand layer section, 3 is a stationary sand layer section, 4 is an incombustible material take-out section, 5 is a boiler combustion section, 6 is a boiler heat transfer section, and 7 is a boiler heat transfer section. A sand sealing device, 8 is a vibrating sieve, 9 is a sand silo, 10 is a sand fixed feeder, 11 is a waste hopper, 12 is a fixed waste feeder, and 13 is a conveyor.

The furnace body A has a rectangular tubular free board 1.
A cylindrical swirling sand layer part 2, a funnel-shaped stationary sand layer part 3,
A boiler B including a boiler combustion part 5 and a boiler heat transfer part 6 is disposed above the free board part 1. That is, the free board part 1 is formed in the shape of a square tube by a water-cooled wall, and light objects in the garbage and ash from the swirling sand layer part 2 are floatingly burned here. Further, the free board portion 1 is formed with an air blowing nozzle 14 for secondary combustion, a sand supply port 15 and a dust supply port 16, respectively.
7. A sand metering feeder 10 and a dust metering feeder 12 are connected to each other.

The swirling sand layer portion 2 is formed in a cylindrical shape, and is constituted by attaching a refractory material 19 to an inner outer surface of a double cylindrical air cooling jacket 18 and fixing it.
Note that, for the refractory 19, Colhart Black, Carborundum, or the like, which is excellent in heat resistance, abrasion resistance, and clinker resistance, and has good heat conductivity, is often used.

The refractory wall forming the swirling sand layer 2 has four circumferentially four and upward and downward steps (a total of 16 steps).
Swing and combustion air blowing nozzle 20 over a number) is formed in the tangential direction, the air C ₁ is a substantially horizontal pivot combustion ejected from each nozzle 20. The air injection angle of the swirling / combustion air blowing nozzle 20 is adjusted so that the swirling diameter D of the fluidized bed to be formed gradually decreases from the upper stage to the lower stage. As shown in FIG. 1, four kinds of swirling airflows having different swirling diameters D are formed. Further, each of the swirling / combustion air blowing nozzles 20 is provided with an air ejection speed adjusting valve 21, and the adjusting valve 21 adjusts the flow velocity of the ejected air. In this embodiment, four nozzles 2 are arranged in the circumferential direction.
Although 0 is arranged, the selection of the number is arbitrary. Similarly, in the present embodiment, the four-stage nozzle 20 extends upward and downward.
Are arranged, but the number of arrangement stages can be arbitrarily selected.

A ring-shaped bubbling flow / combustion air supply duct 22 is provided on the outer peripheral portion of the upper end of the cylindrical stationary sand layer portion 3, and sand flow / combustion air C ₂ is passed through an air duct 23. Supplied. That is, the air supply duct 22 are bored feed nozzle 22a of the sand flow and combustion air C ₂ is as shown in FIGS. 4 and 5, bubbling fluidized-combustion air C ₂ is supplied from the nozzle 22a Is done.

In the present embodiment, the freeboard portion 1 of the furnace body A is formed in the shape of a square tube, but may be in the shape of a polygonal tube or a cylinder. Similarly, it goes without saying that the cross-sectional shapes of the swirling sand layer portion 2 and the stationary sand layer portion 3 may be shapes other than circular. In this embodiment, the air blowing nozzle 20 is formed directly on the furnace wall where the swirling sand layer 3 is formed. However, an air blowing port is formed in the furnace wall, and the nozzle 20 is formed.
May be attached so that the air ejection angle can be adjusted freely. Further, in the present embodiment, the sand flow / combustion air C ₂ is supplied through a ring-shaped air supply duct 22,
The air nozzle 22 is directly connected to the ring-shaped air supply duct 22.
It is configured to perforate the a, but supply system of the fluidized-combustion air C ₂ is, of course it may be any method.

Next, the operation of the fluidized-bed furnace according to the present invention will be described. A predetermined amount of sand F is charged into the furnace body, and the nozzle 2
By ejecting air flow C ₁ 0, the inner rotation sand portion 2 of the furnace body A swirling fluidized sand is also the static sand layer 3 thereunder stationary layer of sand F are respectively formed. Also,
The refuse E and the like are supplied into the furnace main body A by the refuse fixed amount feeder 12 through the refuse supply port 16 and the secondary combustion air C is supplied.
_By the supply of _{3 and the} like and the operation of the ignition device (not shown), heavy combustible waste is fluidly burned in the swirling sand layer portion 2. Further, extremely light combustible waste and ash from the swirling sand layer portion 2 are suspended and burned in the free board portion 1. On the other hand, the sand F and the incombustibles in the furnace main body A are sequentially discharged to the outside of the furnace through the sealing device 7 of the incombustibles take-out section 4, and are separated into the sand F and the incombustibles Eb by the vibrating sieve 8. The separated sand F is returned to the sand silo 9 by the conveyor 13, and is re-sent into the furnace main body 1 from the sand supply port 15 provided above the swirling sand layer 3 via the sand fixed amount feeder 10.

FIG. 6 shows a swirl from each air blowing nozzle 20.
If not supplying combustion air C ₁ (i.e., at rest sand F) is indicative of the state of the furnace body A, the upper nozzle 20a, 20b is exposed from the sand F, lower nozzle 2
0c and 20e are in the sand F. Fa is the level surface of the sand F. Further, FIG. 7 shows the state of the furnace body 1 in the case of supplying a swirling-combustion air C ₁ from each of the air blowing nozzle 20 sand F in swivel sand layer 2 is a swirling fluidized The sand F in the stationary sand layer portion 3 below the lowermost nozzle 20e becomes a stationary sand layer without flowing, and forms a so-called furnace bottom in a normal fluidized furnace.

As described above, the air ejection angle of each of the nozzles 20a to 20e is adjusted so that the diameter D of the swirling flow becomes lower, and the swirling flow rate of the air is about 10
It is controlled by the regulating valve 21 at up to 15 m / sec. When the dust E or the like is supplied into the swirling sand layer 2, the light substance swirls at a high speed in the airflow, and completely burns at a high speed by contact with the air. Note that the reason why the diameter D of the swirling flow is reduced from the upper stage to the lower stage is to put all the input objects on the swirling airflow. Swirling sand layer 2
Small since ash by combustion in the internal flows toward successively upwards, free board section (secondary combustion chamber) receiving the stirring action of the secondary combustion air C ₃ in the 1, is completely combusted. In this embodiment, the gas flow velocity in the free board unit 1 is
1.5 to 2m / sec from the standpoint of preventing entrainment outflow
However, the gas flow rate is appropriately set according to the particle size and specific gravity of the sand F.

On the other hand, an object having a relatively high specific gravity rotates mainly on the outer peripheral portion of the swirling sand layer portion 2 due to the centrifugal action of the swirling airflow, so that the residence time in the sand F becomes long. Further, since the sand concentration of the swirling sand layer portion 2 is higher toward the outer periphery, the amount of heating from the sand increases. As a result, dust and the like burn more rapidly in the outer peripheral portion than in the central portion of the swirling sand layer portion 2. The sand density of the swirling sand layer 2 is adjusted by adjusting the amount of sand supplied. That is, in FIG. 6, the sand density increases as the sand level Fa increases, and the sand density decreases as the Fa level decreases.

FIG. 8 shows the stationary sand layer 3 forming the furnace bottom.
1 shows the state of formation. When the sealing device 7 of the incombustible removal section 4 is operated to discharge the sand of the stationary sand layer 3, the sand F is first discharged from the central portion, and as the amount of discharge increases, a depression is formed as shown by a dotted line. The furnace bottom is formed of a so-called mortar-shaped stationary sand layer. During steady operation of the furnace,
The incombustibles are accumulated in the mortar-shaped furnace bottom sequentially, and are discharged to the outside of the furnace together with the sand when the sand is discharged. The diameter of the mortar-shaped furnace bottom changes by adjusting the amount of sand F discharged. Therefore, the amount of sand discharged is adjusted according to the size of the noncombustible material Eb, and the smooth discharge of the noncombustible material is achieved.

The fluid combustion air C supplied through a nozzle 22a from a ring-shaped fluid combustion air supply duct 22 provided at the boundary between the swirling sand layer portion 2 and the stationary sand layer portion 3.
₂ supplies the sand F into the swirling fluidized sand layer 2 from below by holding the stationary sand layer near the boundary portion in a bubbling flow state and blowing up the sand in this portion upward.
As described above, an object having a high specific gravity and a low combustion speed sequentially sinks toward the furnace bottom on the outer peripheral portion of the swirling sand layer portion 2 due to the centrifugal action of the swirling airflow. , The objects having a long burning time are smoothly burned, and the incombustibles are smoothly transferred to the mortar-shaped bottom in the center.

[0020]

As described above, according to the present invention, a swirling / combustion air blowing nozzle is provided in a plurality of stages on the outer periphery of a swirling sand layer portion of a furnace body, and a plurality of blowing nozzles are provided in each stage in a substantially horizontal and tangential direction. Is supplied to the air to form a swirling air flow in the swirling sand layer portion. As a result, the contact between combustibles and air becomes better than in the conventional bubbling fluidized-bed furnace, so that the burning speed is increased, complete combustion of refuse and the like, and the downsized fluidized-bed furnace can be performed. The refuse is sufficiently supplied to the furnace, and the operation of the furnace does not become unstable as in the conventional bubbling fluidized-bed furnace. Further, in the inside of the swirling sand layer portion, the density of the sand increases and the residence time thereof increases as the outer peripheral portion increases, the amount of heating such as dust increases, and heavy objects move around the swirling sand layer portion due to the centrifugal action of the swirling air current. Will gather in the club. As a result, even if the object has a high specific gravity and is relatively large, it is easily completely burned. Furthermore, since the contact between the air and the combustible material is improved, the amount of CO generated can be reduced and the generation of dioxin can be prevented with a small air ratio.
In the furnace desulfurization and desalination, more efficient desulfurization and desalination can be performed with less consumption of CaCO ₃ .

Further, in the present invention, the diameter of the swirling air flow formed by the swirling / combustion air blowing nozzles of each stage is reduced from the upper stage to the lower stage of the swirling sand layer portion. . As a result, the refuse supplied into the furnace body can smoothly receive not only objects having a high specific gravity but also objects having a low specific gravity into the fluidized sand layer. However, there is no problem that it is difficult to settle into the fluidized bed, and the furnace can be operated more stably. In addition, since each air injection nozzle is provided with an adjusting valve, the amount of air to be injected, the air speed, the number of nozzles to be used, and the like can be freely selected, and efficient combustion can be performed according to the properties of dust and the like. Can be done.

Further, in the present invention, a sand sealing device is provided at the incombustible removal portion below the stationary sand layer, and the amount of sand discharged is adjusted to form a mortar-shaped bottom made of the stationary sand layer. At the same time, sand and incombustibles are discharged out of the furnace together. As a result, the structure of the furnace bottom can be greatly simplified compared to the conventional bubbling type fluidized furnace,
By adjusting the amount of sand discharged and changing the diameter of the mortar-shaped furnace bottom, the incombustibles can be completely prevented from being caught or clogged. Also, to discharge sand and incombustibles out of the furnace together,
The discharge of incombustibles becomes extremely smooth, and the work of maintenance and inspection of the fluidized-bed furnace is greatly reduced. Further, by adjusting the supply amount of the sand, the sand density of the swirling sand layer portion can be controlled, and it becomes easy to cope with the partial load state of the fluidized-bed furnace.

In addition, in the present invention, a ring-shaped air supply duct is provided at the lower end of the swirling sand layer, and the flowing / combustion air is supplied upward through the nozzle into the stationary sand layer. As a result, the sand layer at the outer periphery of the upper end of the stationary sand layer is maintained in a bubbling flow state, so that heavy objects having a long burning time gathering below the swirling sand layer are efficiently burned, and the non-combustible material is burned. Is smoothly transferred into the mortar-shaped stationary sand layer at the center and discharged outside the furnace.
Further, the sand in the stationary sand layer is blown up and supplied into the upper swirling sand layer, whereby the density of the sand layer in the swirling sand layer is maintained in an optimum state. As described above, the present invention has a simple structure and can reduce the size of the furnace, thereby achieving a significant reduction in equipment costs, has excellent combustion performance, and has high practical utility.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a swirling sand bed type fluidized-bed furnace according to 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. 1;

FIG. 4 is a sectional view of a ring-shaped flowing / combustion air supply duct.

FIG. 5 is a partial front view taken along the line CC of FIG. 4;

FIG. 6 is an explanatory view of a sand level surface in a stationary state.

FIG. 7 is an explanatory view of a sand level surface in a flowing state.

FIG. 8 is an explanatory view of a mortar-shaped furnace bottom formed by a stationary sand layer formed in a stationary sand layer portion.

[Explanation of symbols]

A is a furnace body, B is a boiler, C ₁ is air for swirling and combustion, C
₂ is air for flow and combustion, C ₃ is air for floating combustion, D is the diameter of the swirling flow, E is garbage, Ea is flammable, Eb is incombustible,
F is the sand, Fa is the sand level, 1 is the freeboard section, 2 is the swirling sand layer, 3 is the stationary sand layer, 4 is the incombustible material take-out section, 5 is the boiler combustion section, 6 is the boiler heat transfer section, and 7 is sand Sealing device, 8
Is a vibrating sieve, 9 is a sand silo, 10 is a sand fixed feeder,
11 is a waste hopper, 12 is a fixed-quantity feeder for waste, 13
Is a conveyor, 14 is a floating combustion air blowing nozzle, 15 is a sand supply port, 16 is a refuse supply port, 17 is an air supply duct, 18 is an air cooling jacket, 19 is a refractory, and 20 is a swirling / combustion air blowing nozzle. , 21 are air ejection speed adjusting valves,
22 is a ring-shaped flow / combustion air supply duct, 22a is a nozzle, and 23 is an air duct.

Claims (4)

(57) [Claims] 1. A furnace body and provided with a a stationary sand portion and the orbiting sand portion freeboard section and incombustible extracting unit; coloration said cylindrical
While being arranged over a plurality of stages on the outer circumference of the orbiting sand layer portion of the air ejected substantially horizontal and tangential directions from the plurality of positions of the respective stages, towards the upper to the lower in the swivel sand layer portion
And a swirling / incineration air blowing nozzle for forming a plurality of stages of swirling air flows of successively decreasing diameter . 2. An air jet from a swirling / combustion air injection nozzle .
2. The swirling sand layer type flow according to claim 1, wherein the angle is adjusted for each stage , and the diameter of the swirling air flow formed in the swirling sand layer portion over a plurality of stages is gradually reduced from the upper stage to the lower stage. Furnace. 3. A mortar-shaped furnace bottom made of a stationary sand layer is formed in the stationary sand layer by adjusting the amount of sand discharged by providing a sand funnel in the stationary sand layer portion and providing a sand sealing device in the incombustible material take-out portion. The swirling sand bed type fluidized-bed furnace according to claim 1, wherein incombustibles are discharged outside the furnace together with the sand to be discharged. 4. A plurality of air blowing nozzles are provided on an outer periphery of an upper portion of the stationary sand layer located below the swirling sand layer, and the air blowing nozzles are used to flow upward and into the cylindrical stationary sand layer. The swirling sand bed type fluidized bed furnace according to claim 1, wherein air is supplied.