JP2003156206A - Refuse gasifying/fusing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a partial blocking phenomenon where particles such as ash are adhered into a pyrolysis gas nozzle, to allow stable combustion and fusion in a fusing furnace, and to allow fusing slagging by returning noncombustible material and the ash to the fusing furnace, in a refuse gasifying/fusing system. SOLUTION: In the fusing furnace 30, the pyrolysis gas nozzle 31 and an air nozzle 32 for combustion are opened at different positions in the same peripheral wall surface of the fusing furnace 30. A noncombustible material/ash input nozzle 33 is opened on the downstream side than the pyrolysis gas nozzle 31 and the air nozzle 32. Such a constitution prevents the partial blocking phenomenon caused by adhesion of particles such as ash into the nozzle and allows the stable combustion and fusion in a fusing furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste gasification and melting system, and more particularly to a waste gasification and melting system suitable for stable waste combustion and ash melting in a waste treatment device.

[0002]

2. Description of the Related Art In recent years, a waste gasification and melting system using a fluidized bed gasification furnace, which uses combustion heat of the waste itself to melt the ash and incombustibles in the waste to render it harmless, has been put to practical use. Is being started.

In the waste gasification and melting system, the waste is put into a gasification furnace and subjected to a pyrolysis gasification reaction at a low air ratio of about 0.2 to 0.4, and the pyrolysis gas and solid fine particles (char) are ducted. It is an incinerator that sends it to the melting furnace through the furnace, burns it again with air, and uses the heat to melt incombustibles and ash.

In the conventional refuse gasification and melting furnace, the refuse supplied to the fluidized bed gasification furnace reacts with the air supplied to the fluidized bed to generate pyrolysis gas. The pyrolysis gas and the unburned component (char) of fine particles are introduced into a melting furnace together with combustion air and burn at a temperature of 1200 to 1400 ° C.

The heat is used to melt ash and incombustibles into molten slag, which is then discharged to the outside of the system. On the other hand, the exhaust gas is sent to equipment such as a heat recovery device on the downstream side and an exhaust gas treatment device, detoxified and discharged to the outside of the system. In addition, fine particles in the exhaust gas that were not collected in the melting furnace, and slaked lime added for chlorine treatment are collected by a dust collector such as a bag filter on the downstream side of the melting furnace, treated with chemicals and discarded. To be done.

[0006]

As shown in FIG. 6, a tilting swirl-type melting furnace was trial-produced as shown in FIG.
In order to achieve melting, the pyrolysis gas and the combustion air were mixed in the same nozzle 21 and then charged into the melting furnace.

The pyrolysis gas and the combustion air partially burned in the same nozzle to generate heat, whereby unburned materials, incombustible materials, and ash particles were melted and adhered to the inner surface of the nozzle, and the nozzle was partially blocked. At the same time, there is a problem that it is difficult to clean the closed portion.

Further, the incombustible material having a large particle size recovered in the lower part of the gasification furnace and the ash recovered by the bag filter are separately processed in a facility. Returning these to the melting furnace is economically very effective as it eliminates the need to install new equipment for processing them, but in addition, the increase in incombustibles causes melting There was a problem of becoming insufficient.

The object of the present invention is to prevent a partial blockage phenomenon caused by particles such as ash adhering to the inside of the nozzle, to enable stable combustion and melting in the melting furnace, and to return incombustibles and ash to the melting furnace. It is to provide a system capable of forming molten slag by using the above method.

[0010]

The above-mentioned object is to perform thermal decomposition by injecting the pyrolysis gas generated by the reaction with the dust into substantially the same circumferential position on the wall surface of the melting furnace for melting the incombustibles in the dust. This is achieved by a refuse gasification and melting system characterized in that a gas nozzle and a combustion air nozzle for supplying combustion air are installed separately.

According to the present invention, by introducing the pyrolysis gas nozzle and the combustion air nozzle into the melting furnace from different nozzles, the pyrolysis gas burns inside the nozzle and partial clogging due to the adhesion of the molten slag is prevented. It won't happen.

Further, a non-combustible material / ash injection nozzle for introducing all or a part of the non-combustible material and ash separated from the bottom of the gasification furnace and the non-combustible material and ash collected downstream of the melting furnace, By arranging it on a different wall from the wall where the pyrolysis gas nozzle is installed, local cooling due to the injection of incombustibles and ash can be prevented, so that stable melting of incombustibles and ash in the melting furnace is possible. It will be possible.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An outline of an embodiment of the present invention is shown in FIG.
As shown in (c), in the melting furnace 30, the installation positions of the pyrolysis gas nozzle 31, the combustion air nozzle 32, and the incombustible / ash injecting nozzle 33 are defined.

That is, the pyrolysis gas nozzle 31 and the combustion air nozzle 32 are opened at different positions on the same peripheral wall surface of the melting furnace 30. Further, the incombustible / ash injecting nozzle 33 is opened downstream from the pyrolysis gas nozzle 31 and the combustion air nozzle 32. With such a structure, a partial clogging phenomenon caused by adhesion of particles such as ash in the nozzle was prevented, and stable combustion and melting were enabled in the melting furnace.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a side view of the melting furnace, and FIG.
1B is a view taken along the line AA of FIG. 1A, and FIG. 1C is a view of FIG. 1B.
FIG.

As shown in FIG. 1A, the melting furnace 30 has a hollow cylindrical shape in which an internal combustion chamber 24 is surrounded by a furnace wall 25 made of a heat insulating material, and a burner for ignition auxiliary combustion is attached to the left side of the furnace. (Not shown), the left side of the furnace is an outlet for combustion exhaust gas and molten slag. The melting furnace is inclined downward at an angle of 5 to 30 degrees so that the molten slag in the furnace flows out from the outlet.

Further, in the melting furnace 30, a pyrolysis gas nozzle 31, a combustion air nozzle 32, an incombustible material / ash injection nozzle 3 are provided.
3 and the like are installed along a tangential line in the circumferential direction of the melting furnace body, and a swirling flow of gas is formed in the furnace.

In the present embodiment, first, the pyrolysis gas nozzle 31 for injecting the pyrolysis gas 19 and the combustion air nozzle 32 for injecting the combustion air 20 are formed into different nozzles.
They were placed on the same circumference of the furnace wall. An incombustible / ash injecting nozzle 33 for injecting the incombustible / ash 22 is arranged in the central portion of the furnace main body length on the downstream side of the pyrolysis gas nozzle 31 and the combustion air nozzle 32.

Further, the openings of the pyrolysis gas nozzle 31, the combustion air nozzle 32, and the incombustible / ash charging nozzle 33 were installed so as to be horizontal or downward as shown in FIG. 1 (b).

As described above, when the nozzle structure as shown in FIG. 1 is used, combustion does not occur in the pyrolysis gas nozzle because there is no combustion air, so that the nozzle is not clogged. In particular, by arranging the nozzle port horizontally or downward, it is possible to prevent the molten slag flowing downward from entering the nozzle.

Further, in this example, as shown in FIG. 1B, the pyrolysis gas nozzle 31 and the combustion air nozzle 32 are arranged at an angle of 60 degrees. FIG. 2 shows the angle formed by the pyrolysis gas nozzle 31 and the combustion air nozzle 32, the furnace outlet temperature (FIG. (A)), the unburned component concentration (FIG. (B)), and the particle collision point temperature (FIG. (C)). ) And FIG.

When the angle formed by the pyrolysis gas nozzle 31 and the combustion air nozzle 32 is in the range of 40 to 70 degrees, the temperature at the furnace outlet 26 is high and the unburned matter concentration is low. Further, it is necessary to raise the temperature of the portion where the particles collide with the furnace wall surface in order to increase the melting and collection rate of the particles, but it can be seen that when the temperature exceeds 70 degrees, the temperature of the portion where the particles collide decreases.

FIG. 3 shows the relationship between the elapsed operating time and the melting furnace temperature in the melting furnace of this embodiment. According to this embodiment, by controlling the angle between the two, the temperature at the inlet and the outlet of the melting furnace can be made higher than the ash melting temperature, and the unburned matter concentration can be suppressed to be low.

FIG. 4 is a diagram showing the gas temperature in the furnace and the particle scattering rate at the axial position (longitudinal direction of the furnace) of the melting furnace in this embodiment. The gas temperature in the furnace rises from the vicinity of the furnace inlet and remains high. On the other hand, it can be seen that the particle scattering rate of unburned matter and the like becomes high when the length L (axial length) of the furnace is 0.8 L, that is, 80% in the longitudinal direction of the furnace.

Therefore, by disposing the incombustible / ash injecting nozzle for injecting incombustibles and ash into the melting furnace in the longitudinal direction of the melting furnace, the downstream side of the pyrolysis gas nozzle and the combustion air nozzle is used. Incombustibles and ash are added to the place where the temperature inside the furnace is rising due to the decomposition gas and the thermal decomposition gas, and efficient melting can be realized.

In order to prevent particles of incombustibles and ash from scattering from the melting furnace and enable stable melting,
It is preferable to arrange these charging nozzles within 80% of the axial length of the melting furnace.

Further, the opening of the incombustible / ash charging nozzle to the melting furnace is installed horizontally or downward like the pyrolysis gas nozzle and the combustion air nozzle, so that the molten slag can penetrate into the nozzle. Can be prevented, and the clogging of the nozzle can be prevented.

FIG. 5 is a system diagram of a refuse gasification and melting system using a melting furnace according to the present invention. As shown in FIG. 5, dust is supplied from the dust hopper 1 to the gasification furnace 3 through the fixed amount feeder 2. On the other hand, the air supplied to the fluidized bed 5 through the pipe 4 fluidizes the fluidized sand which is the fluidizing medium of the gasification furnace, and reacts with the dust at a temperature of 500 to 650 ° C. to generate pyrolysis gas.

The pyrolysis gas generated in the gasification furnace 3 and the unburned component (char) of fine particles pass through the duct 6 and the inlet nozzle 31.
Is introduced into the melting furnace 7 from the inlet nozzle 32 together with the combustion air and burned. Using the heat, ash and incombustibles are melted and turned into slag. This molten slag is discharged to the outside of the system through the slag discharge port 8 and the slag discharge conveyor 9. On the other hand, the exhaust gas is sent to the downstream equipment through the secondary combustion chamber 10, is rendered harmless, and is discharged to the outside of the system.

Among the solid incombustibles generated in the gasification furnace 3, in the case of the solid incombustibles having a superficial velocity of the superficial part faster than the final velocity of the particle size of the incombustibles, the pyrolysis gas is introduced into the melting furnace 7 through the duct 6. . On the other hand, when the flow velocity of the superficial part is lower than the terminal velocity of the incombustible particles, it is discharged from the lower part of the gasification furnace 3 together with the fluidized sand to the outside of the system, and the fluidized sand is returned to the gasification furnace 3. on the other hand,
The incombustibles are sent to the melting furnace 7 as shown by the transport path 18 and enter the melting furnace through the incombustibles / ash charging nozzle 33 to be melted.

The combustion exhaust gas discharged from the melting furnace 7 burns unburned components in the secondary combustion chamber 10 on the downstream side of the melting furnace, recovers heat in the waste heat recovery boiler 23 and the air heater 11, and cools down the tower 12.
After the temperature is lowered at 1, solid particles in the exhaust gas are collected by a dust collector such as the bag filter 13. The clean exhaust gas is discharged from the chimney 15 by the attracting fan 14.

The solid fine particles collected by the bag filter 13 and the like may contain, in addition to fly ash (fly ash), slaked lime for chlorine removal added immediately before the bag filter, activated carbon, diatomaceous earth and the like. These solid particles are sent to the melting furnace 30 through the transportation path 16 and enter the melting furnace from the incombustible / ash charging nozzle 33 to be melted. In addition, the waste heat recovery boiler 2
3. The incombustibles and ash collected in the temperature reducing tower 12 can also be charged through the nozzle and melted.

[0033]

According to the present invention, in the waste gasification and melting system, by disposing the pyrolysis gas nozzle and the combustion air nozzle separately in the melting furnace, particles such as ash are deposited in the nozzle. The partial blockage phenomenon is avoided, stable combustion is possible, and it becomes possible to return the separately collected incombustibles and ash to the melting furnace and stably melt them.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an example of a nozzle arrangement structure in the present invention.

FIG. 2 is a diagram showing an operation result in the present invention.

FIG. 3 is a diagram for explaining the effect of the attachment angle of the pyrolysis gas nozzle and the combustion air nozzle in the present invention.

FIG. 4 is a diagram for explaining the influence of the incombustibles and the ash injection nozzle on the axial installation position of the melting furnace in the present invention.

FIG. 5 is a system diagram showing a reference example of a waste gasification and melting system.

6 is a structural diagram showing structures of a pyrolysis gas nozzle and a combustion air nozzle used in the reference example of FIG.

[Explanation of symbols]

1 dust hopper 3 gasification furnace 5 fluidized bed 7 melting furnace 8 Slag outlet 9 Slag discharge conveyor 10 Secondary combustion chamber 11 Air heater 12 Cooling tower 13 Bug filter 14 Attraction fan 15 chimney 18 transportation routes 19 Pyrolysis gas 20 Combustion air 21 nozzles 22 Incombustibles / ash 23 Waste heat recovery boiler 24 Combustion chamber 25 furnace wall 26 Melting furnace outlet 30 melting furnace 31 Pyrolysis gas nozzle 32 Combustion air nozzle 33 Incombustibles / ash injection nozzle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kokichi Kameda             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd. F-term (reference) 3K061 AA24 AB03 AC03 BA06 CA08                       DB15                 3K065 AA24 AB03 AC03 BA06 GA03                       GA08 GA12 GA22 GA34

Claims (6)

[Claims] 1. A pyrolysis gas nozzle for injecting pyrolysis gas generated by reaction with dust and combustion air are supplied to substantially the same circumferential position on the wall surface of a melting furnace for melting incombustibles in the refuse. A waste gasification and melting system, characterized in that a combustion air nozzle that is installed is installed separately. 2. The refuse gasification and melting system according to claim 1, wherein the pyrolysis gas nozzle and the combustion air nozzle are installed such that the inlets to the melting furnace are installed horizontally or downward. 3. The combustion air nozzle is arranged upstream of the pyrolysis gas nozzle with respect to the swirling flow in the melting furnace, and the angle formed by the combustion air nozzle and the pyrolysis gas nozzle is The gasification and melting system for waste according to claim 1 or 2, which is installed at 40 to 70 degrees. 4. An incombustible / ash injecting nozzle for injecting incombustibles and ash into the melting furnace is arranged downstream of the pyrolysis gas nozzle and the combustion air nozzle with respect to the longitudinal direction of the melting furnace. The waste gasification and melting system according to any one of claims 1 to 3, which is arranged within 80% of the axial length of the melting furnace. 5. The inlet of the incombustibles / ash injection nozzle to the melting furnace is installed horizontally or downward.
Waste gasification and melting system described in. 6. The incombustible / ash injecting nozzle of the melting furnace comprises:
Incombustibles that are charged with all or part of the incombustibles and ash separated from the bottom of the gasification furnace that produces the pyrolysis gas.
The waste gasification and melting system according to any one of claims 3 to 5, which is an ash injection nozzle.