JPH11267456A - Method and device for removing and decomposing dioxins by unburned ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decompose dioxins and to prevent an increase in discharge od ash and CO2 by obtaining the unburned ash or unburned-ash activated carbon necessary to adsorb and remove the dioxins in a waste gas from such waste as refuse to be disposed of and treating the spent unburned ash or spent unburned-ash activated carbon at high temps. in the system. SOLUTION: In this device, the waste such as refuse is partially burned, the unburned gas thus generated contg. unburned ash is introduced into a dust collector 14 with the collecting efficiency variable, and the unburned ash is collected from the unburned gas in the amt. necessary to adsorb and remove the dioxins in the waste gas from the combustion of the unburned gas. The collected unburned ash is supplied to the dust collector, e.g. a bag filter 16, in the waste gas treating line along with the waste gas, and the spent unburned ash from the bag filter 16 is returned to the ash melting furnace 22 or unburned gas combustion furnace and heated to thermally decompose the dioxins in the ash.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to municipal waste, waste plastic, refuse solid fuel (RDF), waste such as industrial waste, which is expected to generate harmful substances such as dioxins, and the like.
And solid substances containing carbon (hereinafter simply referred to as waste)
In the combustion of the unburned ash or unburned ash, only the necessary amount of activated carbon obtained by activating the unburned ash is supplied to the exhaust gas treatment system,
After adsorbing and removing dioxins, a method for removing and decomposing dioxins by unburned ash, in which unburned ash or unburned ash activated carbon to which dioxins are adsorbed is heated in the system to decompose dioxins. It concerns the device. In addition, solid waste (RDF: Refuse De)
The “live fuel” refers to a fuel formed by adding a calcium compound to municipal waste, industrial waste, or the like that has been subjected to pretreatment such as drying, sorting, and crushing.

[0002]

2. Description of the Related Art When wastes are incinerated, harmful substances such as dioxins may be generated. In particular, the concentration of dioxins in exhaust gas must be 0.1 ng-TEQ / Nm ³ or less. Conventionally, as one method of achieving this goal, there is known a technique in which fine activated carbon is blown into exhaust gas upstream of a bag filter to remove dioxins in the exhaust gas mainly by adsorption (for example, a “filter using a bag filter”). Dioxin Countermeasures Technology ", Yoneda et al., Journal of the Japan Institute of Energy, Vol. 76, No. 10 (1997) 967
968). The used activated carbon collected by the bag filter is burned again or disposed of by landfill.

[0003] Also, JP-A-8-86425 discloses that
Exhaust gas generated in the refuse incinerator is introduced into a bag filter to collect dust, then introduced into a moving bed type adsorption tower, where it comes into contact with activated carbon moving from top to bottom to adsorb dioxins in the exhaust gas -An incinerator for removal is disclosed. Further, Japanese Patent Application Laid-Open No. 9-53815 discloses that a fluid medium containing char and incombustible material is extracted from a fluidized bed portion of a fluidized bed waste incinerator, the char is separated, and the char is added to combustion exhaust gas. And a method of collecting dust and removing trace harmful emissions such as dioxins and mercury.

[0004]

In the conventional method of blowing fine activated carbon into exhaust gas upstream of a bag filter,
The amount of fines activated carbon for flue gas 1 Nm ³ 0.3 to 1
g. For example, in a fluidized bed refuse incinerator with a refuse throughput of 100 t / day, the required amount of fine activated carbon is 150 to 500 kg / day. You can buy this large amount of fine powdered activated carbon from outside,
Or must be introduced into the system such as by producing activated carbon production apparatus, further, since the activated carbon spent trapped in the bag filter are processed by burning or reclamation, of CO ₂ emissions in the combustion process This leads to an increase in the amount of ash and the amount of ash.

[0005] Among the gasification-melting incinerators developed as next-generation incinerators, fluidized-bed gasification furnaces provide fine unburned ash containing a large amount of carbon (char).
Since this has a specific surface area of about several tens of m ² / g (40 to 50 m ² / g), a method of preventing the increase in the amount of ash by using the whole in place of activated carbon for exhaust gas treatment can be considered.
However, in this case, the amount of unburned ash blown becomes extremely large,
There are the following problems. (1) The size of the related systems such as the supply unit and supply line for unburned ash, exhaust gas ducts, and bag filters will increase. (2) The unburned ash discharged from the gasifier has a high temperature,
Since the entire amount is supplied, the temperature of the exhaust gas, which has once dropped, rises, and a dust collecting device having a high-temperature countermeasure such as a high-temperature bag filter for dust collection is required. (3) Dioxins are likely to be generated due to an increase in exhaust gas temperature due to high temperature unburned ash.

Further, in the incineration device of the JP-A 8-86425 Patent described, as activated carbon raw material, coal, and requires waste timber or the like, in the same manner as described above, an increase in gain and ash weight of CO ₂ emissions There is a problem of being connected. Furthermore, in the method for treating combustion exhaust gas described in Japanese Patent Application Laid-Open No. 9-53815, the entire amount of the separated char is supplied to the exhaust gas immediately before the bag filter, and thus there are the above-mentioned problems (1) to (3).

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to partially burn (gasify and combust) an object to be burned, such as waste, and to produce unburned fuel containing a large amount of carbon generated at that time. As an alternative to activated carbon for removing dioxins, only the required amount of ash (char) is collected by a dust collector with a variable collection efficiency, or the unburned ash collected by a dust collector such as a cyclone is used. Only the required amount of unburned ash collected or separated is supplied to the exhaust gas treatment system,
After adsorbing and removing dioxins, the unburned ash adsorbing harmful substances such as dioxins is treated while melting or burning to decompose the dioxins.It is not necessary to introduce activated carbon from outside. An object of the present invention is to provide a method and an apparatus for removing and decomposing species.

Another object of the present invention is to raise the temperature of an activation furnace (activation section) to a high temperature (for example, 750 ° C. or higher) by burning a part of unburned gas or unburned ash obtained by gasification. The unburned ash and activator are supplied here to activate the gas to increase the surface area to have a function as activated carbon, and to supply only the required amount to the exhaust gas treatment system. It is an object of the present invention to provide a method and an apparatus for removing and decomposing dioxins by unburned ash that adsorbs and removes harmful substances such as dioxins therein and does not require the introduction of activated carbon from the outside.

[0009]

In order to achieve the above object, a method for removing and decomposing dioxins using unburned ash according to the present invention comprises the step of partially burning waste to generate unburned ash containing unburned ash. The gas is introduced into a dust collection device with a variable collection efficiency, and unburned ash is collected from unburned gas by the amount required to adsorb and remove dioxins in the exhaust gas produced by burning the unburned gas. The collected unburned ash is supplied together with the exhaust gas to a dust collector of an exhaust gas treatment system, and the used unburned ash from the dust collector is returned to an ash melting furnace or an unburned gas combustion furnace and heated to remove ash from the ash. (See FIGS. 1 to 5). As a dust collector, a bag filter, an electric dust collector, a filter type dust collector, or the like is used.

In the above method, after the unburned ash collected by the dust collector having the function of changing the collection efficiency is activated to form unburned ash activated carbon, the unburned ash activated carbon is collected in the exhaust gas treatment system. May be supplied to the vessel together with the exhaust gas (FIGS. 7 and 8).
reference). In this case, since the specific surface area of the unburned ash is increased to have a function as activated carbon, dioxins in exhaust gas can be adsorbed and removed with a smaller amount of unburned ash.

In the method of the present invention, the waste is partially burned, the unburned gas containing unburned ash is introduced into a dust collector such as a cyclone, and the unburned ash is collected from the unburned gas. Then, of the collected unburned ash, activated by an amount necessary for the adsorption and removal of dioxins in the exhaust gas from which the unburned gas was burned, the unburned ash activated carbon was converted to unburned ash activated carbon. To supply the exhaust gas to the dust collector of the exhaust gas treatment system together with the exhaust gas, return the used unburned ash activated carbon from this dust collector to the ash melting furnace or the unburned gas combustion furnace, and heat it to thermally decompose the dioxins in the ash. (See FIG. 6).

Further, the method of the present invention is characterized in that the waste is partially burned, and an activator is supplied into the unburned gas containing unburned ash to activate the unburned ash to form unburned ash activated carbon. Introduces unburned gas containing unburned ash activated carbon into a dust collector with a variable collection efficiency, absorbs unburned ash activated carbon from unburned gas, and adsorbs dioxins in exhaust gas from burning unburned gas・ Collect only the amount necessary for removal, supply the collected unburned ash activated carbon together with the exhaust gas to the dust collector of the exhaust gas treatment system, and use the used unburned ash activated carbon from this dust collector in the ash melting furnace or The method is characterized in that dioxins in ash are thermally decomposed by returning to an unburned gas combustion furnace and heating (see FIGS. 9 and 10).

An apparatus for removing and decomposing dioxins using unburned ash according to the present invention comprises introducing a gasifier for partially burning waste and an unburned gas containing unburned ash from the gasifier. A dust collecting device with a variable collection efficiency for collecting a part of unburned ash from unburned gas, and introducing unburned gas containing unburned ash from this dust collecting device to burn unburned gas An ash melting furnace for melting unburned ash by combustion heat and introducing unburned ash collected by the dust collector together with exhaust gas from the ash melting furnace to adsorb and remove dioxins in the exhaust gas. And a used unburned ash circulation line for returning used unburned ash from the dust collector to the ash melting furnace (see FIG. 1).

Further, the apparatus of the present invention provides a gasifier for partially burning waste, and an unburned gas containing unburned ash from the gasifier to convert unburned ash from unburned gas. A dust collecting device having a function of changing a collecting efficiency for collecting a part thereof; an activation furnace for activating unburned ash collected by the dust collecting device to form unburned ash activated carbon; An ash melting furnace for introducing unburned gas containing unburned ash from the dust device and exhaust gas from the activation furnace, burning the unburned gas, and melting the unburned ash by combustion heat; and A dust collector for introducing unburned ash activated carbon together with the exhaust gas from the ash melting furnace to adsorb and remove dioxins in the exhaust gas, and returning the used unburned ash activated carbon from this dust collector to the ash melting furnace And a used unburned ash activated carbon circulation line (see FIGS. 7 and 8).

Further, the apparatus of the present invention provides a gasifier for partially burning waste, and an unburned gas containing unburned ash from the gasifier to convert the unburned ash from the unburned gas. A dust collector such as a cyclone for collection, a part of the unburned ash collected by the dust collector and unburned gas from the dust collector are introduced, and the unburned ash is activated to unburned. An activation furnace for converting the ash into activated carbon, and ash melting for introducing the remainder of the unburned ash from the dust collector and exhaust gas from the activation furnace to burn the unburned gas and melt the unburned ash by combustion heat Furnace, a dust collector for introducing unburned ash activated carbon from the activation furnace together with exhaust gas from the ash melting furnace to adsorb and remove dioxins in the exhaust gas, and a used unburned ash from the dust collector. And a used unburned ash activated carbon circulation line for returning the activated carbon to the ash melting furnace. See 6).

The apparatus of the present invention also includes a gasification / activation furnace for partially burning waste and activating unburned ash in the generated unburned gas, and a gasification / activation furnace from the gasification / activation furnace. A dust collection device having a function of changing the collection efficiency for introducing unburned gas containing burned ash activated carbon and collecting a part of the unburned ash activated carbon from the unburned gas; An ash melting furnace for introducing unburned gas containing activated carbon and burning the unburned gas to melt the unburned ash activated carbon by combustion heat; and an ash melting furnace for melting the unburned ash activated carbon collected by the dust collector. Dust collector for adsorbing and removing dioxins in the exhaust gas by introducing it with the exhaust gas from the country, and recycling of the used unburned ash activated carbon for returning the used unburned ash activated carbon from this dust collector to the ash melting furnace And a line (see FIG. 9).

The apparatus of the present invention further comprises a gasification / activation furnace for partially burning waste and activating unburned ash in the generated unburned gas, and a gasification / activation furnace from the gasification / activation furnace. A dust collection device having a function of changing the collection efficiency for introducing unburned gas containing burned ash activated carbon and collecting a part of the unburned ash activated carbon from the unburned gas; An unburned gas combustion furnace for introducing unburned gas containing activated carbon and burning the unburned gas, and introducing unburned ash activated carbon collected by the dust collecting device together with exhaust gas from the unburned gas combustion furnace; A dust collector for adsorbing and removing dioxins in the
A used unburned ash activated carbon circulation line for returning used unburned ash activated carbon from the dust collector to the unburned gas combustion furnace is provided (see FIG. 10).

In the above-mentioned apparatus, as the dust collecting apparatus having the function of changing the collecting efficiency, a variable collecting efficiency inertial dust collecting apparatus having a vertical damper provided therein so as to be vertically movable may be used (see FIG. 1). 2, see FIG. 3), or a cyclone comprising a cylindrical portion, a hopper portion connected to a lower portion of the cylindrical portion, and an inner cylinder provided in the cylindrical portion and having an upper end serving as a gas outlet. An inert gas blowing section is provided in the circumferential direction of the section, and a variable collection efficiency cyclone in which an inert gas supply pipe having a flow control valve is connected to the inert gas blowing section can be used (FIG. 4, (See FIG. 5).

In order to adsorb and remove dioxins without increasing the amount of ash, in the present invention, unburned ash generated by partial combustion (gasification) is directly used as described above.
Alternatively, it is activated and used instead of activated carbon. In this case, it is necessary to reduce the supply amount of unburned ash or unburned ash activated carbon as much as possible.
For this purpose, as described above, the unburned ash dust collector is provided with a function to vary the collection efficiency, and the unburned ash is collected only in an amount necessary for adsorption and removal of dioxins, and the exhaust gas treatment system is provided. Supply. With this configuration, even if the supply amount of the unburned ash is optimized, the amount of the activated carbon is required to be about 10 to about 40 times the amount of the normal activated carbon, considering the specific surface area of the unburned ash. Become. Therefore, in order to further reduce the supply amount, the unburned ash is activated and carbonized to increase the specific surface area. Conventional methods for producing activated carbon are timber,
After carbonizing raw materials such as coconut shell, coal, pitch, waste plastic, etc., it is activated to form activated carbon. As described above, by activating the carbonized raw material, the activated carbon generally has a specific surface area of 800 to 1500 m ² / g.

Incidentally, for example, unburned ash obtained from a fluidized-bed gasification furnace using waste as a raw material contains a large amount of carbon, and its specific surface area is about several tens m ² / g (40 to 50 m ² / g). . Therefore, the unburned ash collected by a dust collector or the like is collected, and water vapor, CO ₂ , O _2, etc. are supplied as an activator, and the energy of waste such as garbage (heat of combustion of unburned gas).
The specific surface area of the unburned ash is increased by activating using unburned ash, and the performance as activated carbon is given. Dioxins are adsorbed and removed using activated carbon obtained from this unburned ash (unburned ash activated carbon) I do. Also, in order to use energy more effectively, only the required amount of unburned ash can be activated using a dust collector with a variable collection efficiency, or collected with a dust collector such as a cyclone. Only the required amount of unburned ash out of the unburned ash is activated.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described for the case where the gasification furnace is a fluidized bed gasification furnace, but the present invention is not limited to the case of a fluidized bed gasification furnace. However, it can be applied to other types of gasification furnaces. FIG. 1 shows an apparatus for removing and decomposing dioxins from unburned ash according to a first embodiment of the present invention. Municipal solid waste, solid waste solid fuel (RDF),
Wastes such as industrial wastes and waste plastics are charged, fluidizing air (primary air) is supplied to the fluidized bed 12 to gasify in a reducing atmosphere, and char (unburned carbon) and fine powder generated are generated. A variable collection efficiency dust collection device 1 installed at the furnace outlet for unburned gas containing unburned ash made of a fluid medium (eg, silica sand), ash, etc.
Then, the dust collecting device 14 collects only an amount necessary for adsorption and removal of dioxins. The collected unburned ash is collected by a dust collector of an exhaust gas treatment system, for example, a bag filter 1.
The air is supplied to the exhaust gas line 18 upstream by, for example, pneumatic conveyance by a blower 20.

The unburned gas from the dust collector 14 is supplied to a pre-combustion unit 24 of a swirling melting furnace 22 for melting ash into slag.
And is supplied with combustion air to burn. The used unburned ash collected by the bag filter 16 is introduced into the pre-combustion section 24 through the used unburned ash circulation line 17 and is discharged from the horizontal cylindrical portion of the swirling melting furnace 22 together with the combustion gas. The tangential direction is introduced into the swirl fusion part 26. The ash is melted by the combustion heat of the unburned gas and discharged as slag. In the pre-combustion unit 24 and the swirling melting unit 26, the used unburned ash is close to the ash melting temperature (for example, 11
(00 to 1600 ° C.), so that the dioxins adsorbed on the unburned ash are decomposed. Swivel fusion part 26
The combustion gas exiting from the gas cooling tower 28 is re-burned as necessary in the gas cooling tower 28, and then heat is recovered in a heat exchanger, a boiler, or the like.
Alternatively, the exhaust gas is cooled by water spraying and the like, and then the cooled exhaust gas is introduced into the air preheater 30 and then into the bag filter 16. The fluidized-bed gasification furnace 10 is of the diffuser type as an example, but may be of the air dispersion plate type.

FIGS. 2 and 3 show a variable dust collection device 1 with a variable collection efficiency.
4 shows an example. The dust collecting device 14 includes the cylindrical body 3
Inside the cylindrical body 32 of the dust collecting device main body 36 composed of the cylindrical body 32 and a hopper section 34 provided continuously below the cylindrical body 32, a vertical collection efficiency variable damper (a fouling plate) 38 is provided. It is configured so as to be movable up and down and has a variable collection efficiency. 40 is a damper driving device, 42 is an exhaust gas inlet, 44 is an exhaust gas outlet, and 46 is a trapping ash outlet. In the above-described dust collecting device 14, as the damper 38 is lowered by the damper driving device 40, a larger amount of unburned ash can be collected. As the damper 38 is raised, the collected amount of unburned ash decreases. . FIGS. 2 and 3 show a case where the main body 36 of the dust collecting device 14 has a rectangular cross section, or may have another shape such as a circular cross section.

A gas analyzer 48 is provided in the exhaust gas line at the outlet of the bag filter 16. The gas analyzer 48 measures measurement items having a correlation with the concentration of dioxins in the exhaust gas, for example, CO 2 in the exhaust gas. The density is measured, and the damper driving device 40 is operated based on this value, and the damper 38 is driven.
It is preferable to configure so as to control the ascending / descending movement. In this case, if the CO concentration in the exhaust gas increases, the damper driving device 40 is operated so that the damper 38 moves down to increase the unburned ash collection amount, and if the CO concentration decreases, the damper driving device 40 Is operated so as to raise the damper 38 to reduce the unburned ash collection amount so that the unburned ash collection amount is always the amount required for exhaust gas treatment in the bag filter 16.

FIGS. 4 and 5 show another example of the variable dust collection device with variable collection efficiency. This dust collector includes a cylindrical portion 50,
A hopper 52 connected to a lower portion of the cylindrical portion 50; and an inner cylinder 5 provided in the cylindrical portion 50 and having an upper end serving as a gas outlet 54.
6, a cyclone 58 comprising the hopper 5
An inert gas blowing unit 60 for blowing an inert gas such as N ₂ is provided in a circumferential direction of the inert gas blowing unit 6.
An inert gas supply pipe 64 having a flow control valve 62 at 0 is connected as a variable collection efficiency cyclone 14a. The inert gas blowing section 60 is composed of, for example, a wind box 66 and a perforated plate 68 such as a perforated plate, and is provided continuously in the circumferential direction of the hopper section 52 or is provided at a plurality of locations intermittently. The flow rate control valve 62 is connected to a flow rate regulator 70 for varying the collection efficiency, and the flow rate regulator 70 is connected to the gas analyzer 4.
8 are connected. In the variable-collection-efficiency cyclone 14a configured as described above, the larger the amount of inert gas blown, the smaller the unburned ash collection efficiency. The efficiency of collecting ash increases.

FIG. 6 shows an apparatus for removing and decomposing dioxins from unburned ash according to a second embodiment of the present invention. In this embodiment, the unburned ash is activated, and the exhaust gas line 18 is activated.
This is to reduce the amount of supply to the system. The unburned ash is collected by a dust collector provided at the furnace outlet of the gasification furnace 10, for example, a cyclone 72, the required amount is sent to the activation furnace 74, and the remainder is sent to the pre-combustion part 24 of the swirling melting furnace 22. The unburned gas after dust collection is guided to the activation furnace 74, and the temperature 75 required for the activation is used.
In order to obtain 0 ° C. or more, an appropriate amount of combustion air is supplied, a part of the unburned gas is burned, and steam or the like is supplied as an activator. The temperature in the activation furnace 74 is adjusted by increasing or decreasing the air supply amount. Exhaust gas containing the remaining unburned gas from the activation furnace 74 is introduced into the pre-combustion section 24 of the swirling melting furnace 22. As a result, the unburned ash activated carbon obtained in the activation furnace 74 is transferred to the exhaust gas line 18 upstream of the bag filter 16.
To adsorb and remove dioxins in exhaust gas. The used unburned ash activated carbon collected and adsorbed and removed by the bag filter 16 is returned to the melting furnace 22 or the gas combustion furnace via the used unburned ash activated carbon circulation line 19 and is adsorbed by the high-temperature treatment. Dioxins are decomposed and processed. Reference numeral 76 denotes a cyclone section of the activation furnace 74. Other configurations and operations are the same as those in the first embodiment.

FIG. 7 shows an apparatus for removing and decomposing dioxins from unburned ash according to a third embodiment of the present invention. In this embodiment, the unburned ash is activated, and the exhaust gas line 18 is activated.
It is configured to incorporate the variable collection efficiency dust collecting device 14 in order to reduce the amount of supply to the dust collector. The amount of unburned ash activated in an activation furnace, for example, a fluidized bed activation furnace 78, is adjusted by the variable collection efficiency dust collecting device 14, and a part of the unburned gas and air and water vapor for burning the unburned gas in the activation furnace 78. Is supplied to raise the temperature in the furnace to 750 ° C. or higher to perform activation. The activated unburned ash activated carbon overflows from the overflow line 82 near the upper surface of the fluidized bed 80, is extracted, and is supplied to the exhaust gas line 18. The fluid medium of the fluidized bed 80 is unburned ash. The remaining unburned gas from the dust collector 14 is supplied to the swirling melting furnace 22. Other configurations and operations are
This is the same as in the first and second embodiments.

FIG. 8 shows an apparatus for removing and decomposing dioxins from unburned ash according to a fourth embodiment of the present invention. In this embodiment, the unburned ash is activated, and the exhaust gas line 18 is activated.
It is configured to incorporate the variable collection efficiency dust collecting device 14 and to use unburned ash as a heat source for setting the temperature in the activation furnace 84 to 750 ° C. or higher. As the activation furnace 84, for example, a cyclone burner-type activation furnace is used, and air, steam, and the like are added to the unburned ash collected by the dust collecting device 14 and introduced into the activation furnace 84. The unburned ash activated carbon extracted from the bottom of the activation furnace 84 is supplied to the exhaust gas line 18, and the exhaust gas from the activation furnace 84 is introduced into the rotary melting furnace 22 together with the unburned gas from the dust collector. In the gas activation using water vapor or the like as an activator, an inorganic gas such as CO or H ₂ is generated at the time of activation.
The exhaust gas from the activation furnace 84 is returned to the unburned gas line as described above. Other configurations and operations are the same as those in the first, second, and third embodiments.

FIG. 9 shows an apparatus for removing and decomposing dioxins from unburned ash according to a fifth embodiment of the present invention. In the present embodiment, the gasification / activation furnace 87 is configured so that the unburned ash is activated in the freeboard section 86 above the gasification furnace 10. Wastes such as municipal solid waste, RDF, industrial waste, and waste plastics are put into the fluidized bed gasifier 10, gasified, and the resulting H ₂ and C are generated.
The unburned gas containing O, HC (hydrocarbon) and the like, and the unburned ash made of a fluid medium of char and fine powder, ash, etc. are guided to the free board section 86 by a gas flow, where steam, carbon dioxide gas,
At the same time as supplying an activator such as oxygen, an appropriate amount of secondary air is supplied to obtain a temperature of 750 ° C. or higher required for activation, and a part of the unburned gas is burned. As a result, the unburned ash in the unburned gas is activated and has the performance as activated carbon. Also in this case, only a required amount of unburned ash activated carbon is collected by the variable collection efficiency dust collecting device 14 provided at the outlet of the gasification furnace 10 and supplied to the exhaust gas line 18. 88 is a blower. Other configurations and operations are the same as those in the first and second embodiments.

FIG. 10 shows an apparatus for removing and decomposing dioxins from unburned ash according to a sixth embodiment of the present invention. In the present embodiment, the unburned ash is activated in the freeboard section 86 above the gasification furnace 10 and the fluidized-bed gas combustion furnace 90 is used instead of the ash melting furnace. The unburned gas containing unburned ash activated carbon from the free board unit 86 is introduced into the variable collection efficiency cyclone 14a,
Only the required amount of unburned ash activated carbon is collected and exhaust gas line 1
8 is supplied. The unburned gas containing the remainder of the unburned ash activated carbon from the cyclone 14a is introduced into the fluidized bed gas combustion furnace 90 and burned, and the exhaust gas from the furnace 90 is supplied to the cyclone 9
After the treatment ash is collected in the gas cooling tower 2, the exhaust gas is cooled in the gas cooling tower 94 and then introduced into the air preheater 30. The used unburned ash activated carbon collected by the bag filter 16 is supplied to the fluidized bed 96 of the fluidized bed gas combustion furnace 90, where it is treated at a high temperature (for example, 800 to 1100 ° C) to decompose dioxins in the ash. . Therefore, the treated ash collected by the cyclone 92 becomes ash containing almost no dioxins. Other configurations and operations are the first and second embodiments,
This is the same as in the case of the five modes.

[0031]

As described above, the present invention has the following effects. (1) There is no need to externally introduce activated carbon necessary for adsorption and removal of dioxins in exhaust gas, and costs and the like are greatly reduced. (2) Unburned ash or unburned ash activated carbon required for adsorption and removal of dioxins in exhaust gas is obtained from waste such as refuse to be treated. Does not increase ash or CO ₂ emissions. Further, the used unburned ash or the used unburned ash activated carbon is subjected to a high temperature treatment in the system to decompose dioxins. (3) Activated charcoal is supplied because the unburned ash required for dioxin removal is supplied by the variable collection efficiency dust collector or by separating the required amount of unburned ash collected by the cyclone. There is no need to unnecessarily increase the size of machines and other related equipment such as auxiliary machines. (4) There is no risk of dioxin formation due to an increase or decrease in exhaust gas temperature. (5) When activating unburned ash to make unburned ash activated carbon,
The amount of unburned ash activated carbon used is about the same or several times the amount of ordinary activated carbon used, and there is no need to remarkably increase the size of related equipment. (6) If the concentration of dioxins in the exhaust gas is extremely high, or if the performance of the unburned ash activated carbon is inferior to the original activated carbon, a larger amount of unburned ash is required to reduce the dioxin concentration in the exhaust gas to the target value. Activated carbon must be supplied, but unburned ash activated carbon is obtained from waste such as refuse to be treated. There is no problem such as an increase in the amount of ash. (7) Collection efficiency The energy can be effectively used by activating the required amount of unburned ash by a variable dust collection device or by separating the required amount of unburned ash collected by the cyclone.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a first embodiment of the present invention.

FIG. 2 is an explanatory longitudinal sectional view showing one example of a variable collection efficiency dust collecting apparatus in FIG. 1;

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is an explanatory longitudinal sectional view showing another example of the variable collection efficiency dust collecting apparatus in FIG. 1;

FIG. 5 is an enlarged view showing an example of a portion surrounded by a chain line circle in FIG.

FIG. 6 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a fourth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a fifth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing an apparatus for removing and decomposing dioxins from unburned ash according to a sixth embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 Fluidized bed gasification furnace 12 Fluidized bed 14 Variable collection efficiency dust collector 14a Variable collection efficiency dust collector (variable collection efficiency cyclone) 16 Bag filter 17 Used unburned ash circulation line 18 Exhaust gas line 19 Used not used Fuel ash activated carbon circulation line 20 Blower 22 Swirling melting furnace 24 Pre-combustion unit 26 Swirling melting unit 28 Gas cooling tower 30 Air preheater 32 Cylindrical body 34 Hopper unit 36 Dust collector body 38 Damper for varying collection efficiency 40 Damper driving device 42 Exhaust gas inlet 44 Exhaust gas outlet 46 Collection ash outlet 48 Gas analyzer 50 Cylindrical part 52 Hopper part 54 Gas outlet 56 Inner cylinder 58 Cyclone 60 Inert gas blowing part 62 Flow control valve 64 Inert gas supply pipe 66 Wind box 68 Plate 70 Variable flow rate controller for variable collection efficiency 72 Cyclone 74 Activation furnace 76 Cyclone section 78 Fluidized bed Active furnace 80 fluidized layer 82 overflow line 84 activating furnace 86 freeboard 87 gasification and activating furnace 88 blower 90 fluidized bed gas combustion furnace 92 cyclone 94 the gas cooling tower

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code FI F23G 7/00 103 B01D 53/34 ZAB F23J 1/00 B09B 3/00 302E 15/00 303L F23J 15/00 J

Claims (11)

[Claims] 1. An unburned gas containing unburned ash generated by partially burning waste is introduced into a dust collector having a function of varying a collection efficiency, and the unburned ash is converted from the unburned gas into unburned gas. It collects only the amount necessary for adsorption and removal of dioxins in the exhaust gas from combustion of ash, and supplies the collected unburned ash together with the exhaust gas to the exhaust gas treatment system dust collector, where it is used. A method for removing and decomposing dioxins by unburned ash, wherein the unburned ash is returned to an ash melting furnace or an unburned gas combustion furnace and heated to thermally decompose dioxins in the ash. 2. A method for activating unburned ash collected by a dust collector having a function of varying collection efficiency to form unburned ash activated carbon, and the unburned ash activated carbon is discharged to a dust collector of an exhaust gas treatment system. The method for removing and decomposing dioxins with unburned ash according to claim 1, which is supplied together with the unburned ash. 3. A method for partially burning waste, introducing unburned gas containing unburned ash to a dust collector, collecting unburned ash from unburned gas, and collecting the collected unburned ash. Of these, the unburned ash activated carbon was activated by activating only the amount required for adsorption and removal of dioxins in the exhaust gas from the combustion of the unburned gas, and this unburned ash activated carbon was discharged into the exhaust gas treatment system dust collector. Supply with
Removal of dioxins by unburned ash, characterized in that used unburned ash activated carbon from this dust collector is returned to an ash melting furnace or unburned gas combustion furnace and heated to thermally decompose dioxins in ash. Disassembly method. 4. After partially burning the waste and supplying an activator to the unburned gas containing unburned ash generated to activate the unburned ash to form unburned ash activated carbon, the unburned ash activated carbon is removed. Unburned ash activated carbon is introduced from unburned gas by introducing unburned gas containing dust into a dust collector with a variable collection efficiency, and the amount required to adsorb and remove dioxins in the exhaust gas from burning the unburned gas. Only collected,
The collected unburned ash activated carbon is supplied together with the exhaust gas to a dust collector of an exhaust gas treatment system, and the used unburned ash activated carbon from the dust collector is returned to an ash melting furnace or an unburned gas combustion furnace and heated to form ash. A method for removing and decomposing dioxins by unburned ash, which comprises thermally decomposing dioxins therein. 5. A gasification furnace for partially burning waste, and an unburned gas containing unburned ash from the gasification furnace is introduced to collect a part of the unburned ash from the unburned gas. And a ash for introducing unburned gas including unburned ash from the dust collector, burning the unburned gas, and melting the unburned ash by heat of combustion. A melting furnace; a dust collector for introducing unburned ash collected by the dust collector together with exhaust gas from the ash melting furnace to adsorb and remove dioxins in the exhaust gas; and use from the dust collector. A device for removing and decomposing dioxins using unburned ash, comprising: a used unburned ash circulation line for returning used unburned ash to an ash melting furnace. 6. A gasification furnace for partially burning waste, and an unburned gas containing unburned ash from the gasification furnace is introduced to collect a part of the unburned ash from the unburned gas. A dust collecting device having a function to change the collection efficiency, an activation furnace for activating unburned ash collected by the dust collecting device to form unburned ash activated carbon, and an unburned fuel from the dust collecting device. An ash melting furnace for introducing unburned gas containing ash and exhaust gas from the activation furnace to burn the unburned gas and melt the unburned ash by combustion heat; and unburned ash activated carbon from the activation furnace is ashed. A dust collector that is introduced together with the exhaust gas from the melting furnace to adsorb and remove dioxins in the exhaust gas, and a spent unburned ash that returns the used unburned ash activated carbon from this dust collector to the ash melting furnace Removal of dioxins by unburned ash characterized by having an activated carbon circulation line
Disassembly device. 7. A gasifier for partially burning waste, and a collector for introducing unburned gas containing unburned ash from the gasifier and collecting unburned ash from the unburned gas. A dust collector, and an activation furnace for introducing a part of the unburned ash collected by the dust collector and unburned gas from the dust collector, and activating the unburned ash to form unburned ash activated carbon. An ash melting furnace for introducing the remainder of the unburned ash from the dust collector and the exhaust gas from the activation furnace to burn the unburned gas and melt the unburned ash by combustion heat; A dust collector for introducing the burnt ash activated carbon together with the exhaust gas from the ash melting furnace to adsorb and remove dioxins in the flue gas, and a dust collector for returning the used unburned ash activated carbon from the dust collector to the ash melting furnace Dioxin removal by unburned ash characterized by having a used unburned ash activated carbon circulation line
Disassembly device. 8. A gasification / activation furnace for partially burning waste and activating unburned ash in the generated unburned gas, and a gasification / activation furnace containing unburned ash activated carbon from the gasification / activation furnace. A dust collection device having a function to collect a part of the unburned ash activated carbon from the unburned gas by introducing the combustion gas, and a unburned gas containing the unburned ash activated carbon from the dust collection device An ash melting furnace for burning unburned ash activated carbon by combustion heat by introducing unburned gas, and introducing unburned ash activated carbon collected by the dust collector together with exhaust gas from the ash melting furnace. A dust collector for adsorbing and removing dioxins in exhaust gas, and a used unburned ash activated carbon circulation line for returning used unburned ash activated carbon from the dust collector to an ash melting furnace. Removal of dioxins by unburned ash
Disassembly device. 9. A gasification / activation furnace for partially burning the waste and activating unburned ash in the generated unburned gas, and a gasification / activation furnace containing unburned ash activated carbon from the gasification / activation furnace. A dust collection device having a function to collect a part of the unburned ash activated carbon from the unburned gas by introducing the combustion gas, and a unburned gas containing the unburned ash activated carbon from the dust collection device An unburned gas combustion furnace for introducing unburned gas and introducing unburned ash activated carbon collected by the dust collector together with exhaust gas from the unburned gas combustion furnace to adsorb dioxins in the exhaust gas・ A dust collector for removing, and a used unburned ash activated carbon circulation line for returning used unburned ash activated carbon from the dust collector to an unburned gas combustion furnace are provided. A device for removing and decomposing dioxins using unburned ash. 10. The variable dust collection device having a variable collection efficiency function is a variable collection efficiency inertial dust collection device having a vertically arranged damper movably provided therein.
An apparatus for removing and decomposing dioxins with unburned ash according to 6, 8, or 9. 11. A dust collecting apparatus having a function of changing a collection efficiency includes a cylindrical portion, a hopper portion connected to a lower portion of the cylindrical portion, and an inner cylinder provided in the cylindrical portion and having an upper end serving as a gas outlet. A cyclone having an inert gas injection portion provided in a circumferential direction of the hopper portion, and an inert gas supply pipe having a flow control valve connected to the inert gas injection portion. The apparatus for removing and decomposing dioxins by unburned ash according to claim 5, 6, 8, or 9.