WO2004092649A1

WO2004092649A1 - Gasification and slagging combustion method and apparatus

Info

Publication number: WO2004092649A1
Application number: PCT/JP2004/005369
Authority: WO
Inventors: Tomoyuki Shiina; Yuichi Iida; Takao Kobayashi
Original assignee: Ebara Corporation
Priority date: 2003-04-16
Filing date: 2004-04-15
Publication date: 2004-10-28
Also published as: TW200424479A; JP2008069984A

Abstract

The present invention relates to a gasification and slagging combustion method for gasifying combustibles, delivering produced gas and char (solid carbon) into a slagging combustion furnace, and combusting the gas and char at a high temperature and melting fly ash into molten slag in the slagging combustion furnace. The gasification and slagging combustion method includes gasifying combustibles in a gasification furnace (10) to produce a gas and a char, melting ash contained in the gas and the char in the slagging combustion furnace (11) while combusting the gas and the char at a temperature enough to melt the ash, discharging incombustibles through a discharge port from the gasification furnace and removing metals from the incombustibles discharged, crushing the incombustibles from which the metals are removed, and supplying the crushed incombustibles to the gasification furnace (10) or the slagging combustion furnace (11) or the duct.

Description

DESCRIPTION

GASIFICATION AND SLAGGING COMBUSTION METHOD AND APPARATUS

Technical Field The present invention relates to a gasification and slagging combustion method and apparatus for gasifying combustibles including municipal wastes, industrial wastes, biomass, and the like, delivering produced gas and char (solid carbon) into a slagging combustion furnace, and combusting the gas and char at a high temperature and melting ash into molten slag in the slagging combustion furnace .

Background Art In recent years, there has been employed a process of gasifying (pyrolyzing) wastes such as municipal wastes, industrial wastes, biomass or medical wastes in a reducing atmosphere within a fluidized-bed gasification furnace, introducing gas, char and ash produced by gasification into a slagging combustion furnace (ash melting furnace) , and combusting the gas and char at a high temperature and melting the ash in the slagging combustion furnace.

As a conventional gasification and slagging combustion system (ash melting system) , there has been proposed a fluidized-bed gasification and slagging combustion furnace disclosed in Japanese laid-open patent publication No. 7- 332614, for example. According to the fluidized-bed gasification and slagging combustion furnace disclosed in this patent publication, since a temperature of a fluidized bed is relatively low, pyrolysis gas can be stably produced and pyrolysis residues can be stably supplied to a swirling-type slagging combustion furnace, and hence highly stable combusting conditions can be maintained in the swirling-type slagging combustion furnace. Therefore, the temperature in the swirling-type slagging combustion furnace can be maintained stably. One of features of this fluidized-bed gasification and slagging combustion furnace is that fly ash in the produced gas can be melted into molten slag by utilizing the calorie of combustibles such as wastes, and hence the disposal amount of fly ash can be reduced.

Further, in the case where the gasification furnace comprises a fluidized-bed gasification furnace, incombustibles are discharged together with a fluidized medium such as sand from the • furnace bottom of the gasification furnace, and the incombustibles and the fluidized medium (sand) are separated from each other by a vibrating screen. Then, valuable metals in the incombustibles are recovered, i.e., iron in the incombustibles is recovered by a magnetic separator and aluminum is recovered by an aluminum separator, and then the remaining incombustibles are discarded as residue in a landfill site. The amount of the incombustibles (residue) to be discarded in the landfill site occupies 1.5 to 5 % of the amount of wastes to be treated (the total amount of wastes supplied as an object to be treated) by weight. These incombustibles to be discarded have been an obstacle to reduction of the final disposal amount discharged to the outside of the gasification and slagging combustion system.

In order to reduce the final disposal amount, even if incombustibles are returned directly to the gasification furnace in masses, the incombustibles are discharged from the furnace bottom as they are, and hence the incombustibles are merely circulated in the system (the gasification furnace and an incombustible discharge and return passage) . Thus, the incombustibles are not discharged to the outside of the system, and the amount of the circulating incombustibles increases gradually, resulting in malfunction of the gasification furnace. On the other hand, if the incombustibles are directly supplied to the slagging combustion furnace in masses, the incombustibles masses are accumulated in the bottom of the slagging combustion furnace, and slag cannot be smoothly discharged.

Disclosure of Invention The present invention has been made in view of the foregoing drawbacks. It is an object of the present invention to provide a gasification and slagging combustion method and apparatus which can properly treat incombustibles contained in combustibles such as wastes and discharged from the bottom of the gasification furnace, can reduce the final disposal amount discharged to the outside of the overall system, and can be operated stably.

In order to achieve the above subject, according to a first aspect of the present invention, there is provided a gasification and slagging combustion method for treating combustibles, comprising: gasifying combustibles in a gasification furnace to produce a gas and a char; introducing the gas and the char into a slagging combustion furnace through a duct; melting ash contained in the gas and the char in the slagging combustion furnace while combusting the gas aηd the char at a temperature enough to melt the ash; discharging incombustibles through a discharge port from the gasification furnace and removing metals from the incombustibles discharged; crushing the incombustibles from which the metals are removed; and supplying the crushed incombustibles to the gasification furnace or the slagging combustion furnace or the duct.

According to the first aspect of the present invention, the incombustibles discharged from the gasification furnace are separated, metals are removed from the separated incombustibles, the incombustibles from which the metals are removed are crashed, the crashed incombustibles are stored, and then the stored incombustibles are discharged at a constant rate and supplied to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, most of the incombustibles discharged from the bottom of the gasification furnace can be melted into molten slag, the final disposal amount discharged to the outside of the overall gasification and slagging combustion apparatus can be reduced, and the gasification and slagging combustion apparatus can be stably operated. According to a preferred aspect of the present invention, after crushing the incombustibles, the crushed incombustibles may be stored in a hopper.

According to a preferred aspect of the present invention, the fly ash recovered from the exhaust gas discharged from the slagging combustion furnace may be supplied together with the crushed incombustibles to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, slagging rate of the overall gasification and slagging combustion apparatus can be increased, and the amount of fly ash discharged to the outside of the overall gasification and slagging combustion system can be reduced.

According to a preferred aspect of the present invention, the crushed incombustibles may be supplied at a constant rate to the gasification furnace or the slagging combustion furnace or the duct.

According to a preferred aspect of the present invention, the crushed incombustibles may be supplied at a variable rate to the gasification furnace or the slagging combustion furnace or the duct.

According to a preferred aspect of the present invention, the amount of the crushed incombustibles supplied to the gasification furnace or the slagging combustion furnace or the duct may be adjusted so that a temperature in the slagging combustion furnace becomes 1200 °C or higher.

According to a preferred aspect of the present invention, the gasification and slagging combustion apparatus may include a separating and classifying device for separating the incombustibles discharged from the gasification furnace and removing metals from the separated incombustibles, a crushing device for crushing the incombustibles, which has been separated by the separating and classifying device, from which metals are removed, and a constant feeder for supplying the incombustibles which has been crushed by the crushing device at a constant rate to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace after storing the crushed incombustibles. Therefore, most of the incombustibles discharged from the bottom of the gasification furnace can be melted into molten slag, and hence the final disposal amount discharged to the outside of the overall gasification and slagging combustion apparatus can be reduced, and the gasification and slagging combustion apparatus can be stably operated.

According to a preferred aspect of the present invention, an exhaust gas is discharged from said slagging combustion furnace and fly ash which is recovered from the exhaust gas may be supplied to the gasification furnace or the slagging combustion furnace or the duct.

A fly ash recovery device for recovering the fly ash from the exhaust gas discharged from the slagging combustion furnace may be provided, and the fly ash recovered by the fly ash recovery device may be supplied into the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, slagging rate of the overall gasification and slagging combustion apparatus can be increased, and the amount of fly ash discharged to the outside of the overall gasification and slagging combustion system can be reduced.

According to a second aspect of the present invention, there is provided a gasification and slagging combustion apparatus for treating combustibles, comprising: a gasification furnace that gasifies combustibles to produce a gas and char, the gasification furnace having a discharge port for discharging incombustibles from the gasification furnace; a slagging combustion furnace that melts ash contained in the gas and the char produced by gasification while combusting the gas and the char at a temperature enough to melt the ash; a duct configured to supply the gas and the char from the gasification furnace into the slagging combustion furnace; a separating and classifying device configured to separate ^' and classify the incombustibles discharged from the discharge port; a removing device configured to remove metals from the separated incombustibles; a crusher configured to crush the incombustibles from which metals are removed; and a supplying device configured to supply the crushed incombustibles to the gasification furnace or the slagging combustion furnace or the duct.

According to a preferred aspect of the present invention, the gasification and slagging combustion apparatus may further comprise a hopper configured to store the crushed incombustibles after the incombustibles are crushed.

According to a preferred aspect of the present invention, the supplying device may comprise a constant feeder configured to feed the crushed incombustibles at a constant rate.

According to a preferred aspect of the present invention, the supplying device may comprise a variable feeder configured to feed the crushed incombustibles at a variable rate. According to a preferred aspect of the present invention, the supplying device may have a regulating device configured to adjust the amount of the crushed incombustibles supplied to the gasification furnace or the slagging combustion furnace or the duct so that a temperature in the slagging combustion furnace becomes 1200 °C or higher.

According to a preferred aspect of the present invention, the gasification and slagging combustion apparatus may further comprise a fly ash recovery device configured to recover fly ash from exhaust gas discharged from the slagging combustion furnace; and a fly ash supply device configured to supply the fly ash recovered by the fly ash recovery device to the gasification furnace or the slagging combustion furnace or the duct.

Brief Description of Drawings FIG. 1 is a schematic view showing a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to an embodiment of the present invention;

FIG. 2 is a schematic view showing a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to another embodiment of the present invention; FIG. 3 is a schematic view showing a part of a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to an embodiment of the present invention; and FIG. 4 is a schematic view showing a part of a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to another embodiment of the present invention.

Best Mode for Carrying Out the Invention

A gasification and slagging combustion method and apparatus according to embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to an embodiment of the present invention. As shown in FIG. 1, a gasification and slagging combustion apparatus comprises a fluidized-bed gasification furnace 10 and a slagging combustion furnace 11. The fluidized-bed gasification furnace 10 has a fluidized bed 10a where a fluidized medium such as silica sand is fluidized by a fluidizing gas introduced from a bottom of the fluidized-bed gasification furnace 10. In the fluidized-bed gasification furnace 10, combustibles 13 such as wastes which are supplied therein from a combustibles supply device 12 are gasified, and a gas Gl produced by gasification is discharged from a gas outlet 10b.

Further, in the slagging combustion furnace 11, the produced gas Gl discharged from the fluidized-bed gasification furnace 10 is introduced therein from a gas inlet 11a, is mixed with air introduced therein, and the produced gas Gl and char (solid carbon) contained in the gas Gl are combusted at a high-temperature, thereby melting fly ash contained in the produced gas at a high temperature into molten slag A, discharging the molten slag A from a slag discharge port lib to the outside of the system, and discharging combustion exhaust gas G2 from a gas outlet lie.

Incombustibles discharged from the bottom of the fluidized-bed gasification furnace 10 are discharged together with the fluidized medium through incombustibles discharge passages 14 communicating with the furnace bottom to an incombustibles discharger 15. Then, the incombustibles and the fluidized medium are discharged from the incombustibles discharger 15 and supplied to a vibrating screen 16. In the vibrating screen 16, the incombustibles B and the fluidized medium (sand) C are separated from each other, and the incombustibles B are supplied to a magnetic separator and aluminum separator 17 serving as a removing device to remove metals . On the other hand, the fluidized medium C is supplied to a fluidized medium conveyor (elevator) 18, and is then returned to the fluidized bed 10a of the fluidized-bed gasification furnace 10 through a screw feeder 19.

In the magnetic separator and aluminum separator 17, valuable metals D such as iron or aluminum are recovered from the supplied incombustibles B. Specifically, iron is recovered by the magnetic separator and aluminum is recovered by the aluminum separator. The valuable metals D recovered by the magnetic separator and aluminum separator 17 are discharged to the outside of the system. The incombustibles E other than the valuable metals D are stored in an incombustibles hopper 20. The incombustibles E stored in the incombustibles hopper 20 are discharged at a constant rate by a discharging device (not shown) such as a screw-type discharger provided at the bottom of the hopper. The discharged incombustibles E are crushed coarsely into a size of about 10 mm or less by a crusher

21, and then metal masses F which will be an obstacle to operation of a mill 24 are removed by a vibrating screen

22. Although it is possible not to provide the crusher 21, it is desirable to provide the crusher 21 in order to avoid increase of the final disposal amount which is caused by discharge of the coarse incombustibles to the side of the metal masses F.

After the incombustibles E are coarsely crushed by the crusher 21, the crushed incombustibles H from which the metal masses F are removed are stored in a hopper 23. The crushed incombustibles H stored in the hopper 23 is discharged at a constant rate by a discharging device 23a such as a screw-type discharger provided at the bottom of the hopper 23. The discharged incombustibles H are supplied to the mill 24 by a conveyor, and are milled into crushed incombustibles I in the mill 24. Then, the crushed incombustibles I are pneumatically transported by a pneumatic transportation mechanism 24a, and stored in a hopper 25. The mill 24 may comprise a roller mill, a ball mill, a rod mill, or the like.

The combustion exhaust gas G2 discharged from the gas outlet lie of the slagging combustion furnace 11 is drawn by an induced draft fan 29 into a waste heat boiler 26 in which heat recovery of the combustion exhaust gas G2 is carried out. Thereafter, the combustion exhaust gas G2 passes through an air preheater 27 and a bag filter 28, and is then discharged from a stack 30 to the atmosphere. Fly ash J accumulated at the bottom of the waste heat boiler 26 and the air preheater 27 is discharged by a screw conveyor 26a and a screw conveyor 27a provided at the respective bottoms of the waste heat boiler 26 and the air preheater 27, and part of the ash J is supplied to the fluidized-bed gasification furnace 10 by a conveyor line 34 and the remaining ash is stored in a hopper 32. Further, part of fly ash K in the combustion exhaust gas G2 trapped by the bag filter 28 is supplied to the fluidized-bed gasification furnace 10 by the conveyor line 34, and the remaining fly ash is stored in the hopper 32.

Ash M stored in the hopper 32 is discharged to the outside of the system for chemical treatment. Thus, the problem of heavy metal concentrate or the like can be avoided. The crushed incombustibles I stored in the hopper 25 is discharged at a constant rate by a discharging device 25a such as a rotary valve or a rotary feeder provided at the bottom of the hopper, and the discharged incombustibles I are supplied to the conveyor line 34. The conveyor line 34 serves as a conveyor line for supplying fly ash L comprising a mixture of the ash J from the waste heat boiler 26 and the air preheater 27 and the fly ash K from the bag filter 28 to the fluidized-bed gasification furnace 10. By supplying the crushed incombustibles I to the conveyor line 34, the crushed incombustibles I are mixed with the fly ash L and supplied to the fluidized-bed gasification furnace 10. The conveyor line 34 may be connected to the combustibles supply device 12, and a mixture of the crushed incombustibles I and the fly ash L may be supplied together with the combustibles to the fluidized-bed gasification furnace 10.

The mixture of the crushed incombustibles I and the fly ash L supplied to the fluidized-bed gasification furnace 10 is mixed with the produced gas Gl of the fluidized-bed gasification furnace 10, and is supplied from the fluidized-bed gasification furnace 10 scatteringly into the slagging combustion furnace 11 by pneumatic transportation. Then, the mixture of the crushed incombustibles I and the fly ash L is melted into molten slag A in the slagging combustion furnace 11, and the molten slag A is discharged from the slag discharge port lib to the outside of the system.

The amount of the incombustibles discharged from the hopper 23 and the amount of the incombustibles discharged from the hopper 25 are preferably regulated by making rotational speeds of the discharging device 23a and the discharging device 25a variable. With this arrangement, the amount of the crushed incombustibles H and the amount of the crushed incombustibles I discharged from the respective hoppers 23, 25 can be changed properly depending on operating conditions.

The particle size of the crushed incombustibles I milled in the mill 24 is preferably not more than 300μm. This is because after the crushed incombustibles I are supplied to the fluidized-bed gasification furnace 10, the crushed incombustibles I having such size are liable to be scattered properly together with the gas Gl produced in the gasification furnace into the slagging combustion furnace 11.

FIG. 2 is a schematic view showing a gasification and slagging combustion apparatus for carrying out a gasification and slagging combustion method according to another embodiment of the present invention. In FIGS. 1 and 2, like or corresponding parts are denoted by like or corresponding reference numerals, and repetitive description is eliminated.

The gasification and slagging combustion apparatus shown in FIG. 2 is different from the gasification and slagging combustion apparatus shown in FIG. 1 in that the crushed incombustibles I discharged from the hopper 25 at a constant rate by the discharging device 25a provided at the bottom of the hopper 25 are supplied to the hopper 32 for storing return ash, fly ash J and K stored in the ash hopper 31 is supplied to the hopper 32, the crushed incombustibles I and the fly ash J and K are mixed with each other in the hopper 32 and then discharged at a constant rate by a discharging device such as a rotary valve or a rotary feeder provided at the bottom of the hopper 32, and the mixture L of the discharged incombustible I and the fly ash J and K is pneumatically transported through a transportation pipe 35 by a blower 33 and then blown into the slagging combustion furnace 11 from a blowing nozzle 36 mounted on the gas inlet 11a of the slagging combustion furnace 11. The crushed incombustibles I blown in the slagging combustion furnace 11 are melted in the furnace and recovered as molten slag A in the same manner as the gasification and slagging combustion apparatus shown in FIG. 1.

Although the mixture L of the incombustibles I and the fly ash J and K is supplied from the blowing nozzle 36 mounted on the gas inlet 11a into the slagging combustion furnace 11 in the above embodiment, the mixture L may be supplied from a blowing nozzle mounted on the top of the slagging combustion furnace 11 or the upper side part of the slagging combustion furnace 11.

Because the crushed incombustibles I have high abrasion property, the transportation pipe 35, particularly a bent tube portion of the transportation pipe 35 is preferably composed of abrasion resistance material such as an alumina lining pipe. A part of ash M stored in the ash hopper 31 is discharged to the outside of the system for chemical treatment. Thus, the problem of heavy metal concentrate or the like can be avoided.

Although the crushed incombustibles I and the fly ash J and K are supplied to the fluidized-bed gasification furnace 10 or the slagging combustion furnace 11 in the above embodiments, as shown in FIG. 3, the conveyor line 34 for conveying the fly ash L comprising a mixture of the incombustibles I from the hopper 25, the fly ash J from the waste heat boiler 26 and the air preheater 27, and the fly ash K from the bag filter 28 may be connected to a duct 37 for introducing the produced gas Gl from the fluidized-bed gasification furnace 10 (not shown) into the slagging combustion furnace 11, and the mixture of the incombustible I and the fly ash L may be supplied to the duct 37. Further, as shown in FIG. 4, the mixture L of the incombustibles I discharged from the hopper 32 and the fly ash J and K may be supplied into a duct 37 for introducing the produced gas Gl from the fluidized-bed gasification furnace 10 (not shown) into the slagging combustion furnace 11. In the above embodiments, when the crushed incombustibles are supplied to the gasification furnace or the slagging combustion furnace _;or the duct for introducing the produced gas into the slagging combustion furnace, the temperature in the slagging combustion furnace is slightly lowered. Therefore, the amount of the crushed incombustibles supplied to the gasification furnace or the slagging combustion furnace or the duct is adjusted so that the temperature in the slagging combustion furnace becomes 1200 °C or higher. Further, when the amount of the crushed incombustibles remaining in the hopper becomes large, the amount of the crushed incombustibles supplied to the gasification furnace or the slagging combustion furnace or the duct is adjusted to be increased. Conversely, when the amount of the crushed incombustibles remaining in the hopper becomes small, the amount of the crushed incombustibles supplied to the gasification furnace or the slagging combustion furnace or the duct is adjusted to be decreased.

In order to recycle (effectively utilize) slag, the amount of harmful metal (particularly, concentration of lead) contained in the slag is required to be a predetermined amount or less. Particularly, it is necessary to maintain the concentration of lead at a predetermined value or less. It is desirable that the amount of fly ash returned to the gasification furnace or the slagging combustion furnace or the duct is adjusted so that the concentration of lead per 1 kg of slag (dry weight) is 150 mg or less, preferably 100 mg or less. Further, when the amount of ash adhered to the waste heat boiler increases, the ash covers the entire transfer surface of the boiler, thus lowering efficiency of heat transfer. In order to prevent the lowering of the efficiency of heat transfer, when data indicating the increased amount of ash adhered to the transfer surface of the boiler is obtained, for example, when a periodic inspection is conducted, or the heat exchange is not performed properly and the exhaust gas in the boiler has a high temperature, the amount of the fly ash returned to the gasification furnace or the slagging combustion furnace or the duct is adjusted to be decreased.

As described above, the present invention offers the following excellent advantages:

(1) The incombustibles discharged from the gasification furnace are separated, metals are removed from the separated incombustibles, the incombustibles from which the metals are removed are crashed, the crashed incombustibles are stored, and then the stored incombustibles are discharged at a constant rate and supplied to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, most of the incombustibles discharged from the bottom of the gasification furnace can be melted into molten slag, the final disposal amount discharged to the outside of the overall gasification and slagging combustion apparatus can be reduced, and the gasification and slagging combustion apparatus can be stably operated. (2) The fly ash recovered from the exhaust gas discharged from the slagging combustion furnace is supplied together with the crushed incombustibles to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, slagging rate of the overall gasification and slagging combustion apparatus can be increased, and the amount of fly ash discharged to the outside of the overall gasification and slagging combustion system can be reduced. (3) The gasification and slagging combustion apparatus includes a separating and classifying device for separating the incombustibles discharged from the gasification furnace and removing metals from the separated incombustibles, a crushing device for crushing the incombustibles, which has been separated by the separating and classifying device, from which metals are removed, and a constant feeder for supplying the incombustibles which has been crushed by the crushing device at a constant rate to the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace after storing the crushed incombustibles. Therefore, most of the incombustibles discharged from the bottom of the gasification furnace can be melted into molten slag, and hence the final disposal amount discharged to the outside of the overall gasification and slagging combustion apparatus can be reduced, and the gasification and slagging combustion apparatus can be stably operated.

(4) A fly ash recovery device for recovering the fly ash from the exhaust gas discharged from the slagging combustion furnace is provided, and the fly ash recovered by the fly ash recovery device is supplied into the gasification furnace or the slagging combustion furnace or the duct for introducing the produced gas into the slagging combustion furnace. Therefore, slagging rate of the overall gasification and slagging combustion apparatus can be increased, and the amount of fly ash discharged to the outside of the overall gasification and slagging combustion system can be reduced. Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims .

Industrial Applicability The present invention is preferably applicable to a gasification and slagging combustion system for gasifying combustibles such as municipal wastes, industrial wastes, and biomass, delivering produced gas and char (solid carbon) into a slagging combustion furnace, and combusting the gas and char and melting ash in the slagging combustion furnace .

Claims

1. A gasification and slagging combustion method for treating combustibles, comprising: gasifying combustibles in a gasification furnace to produce a gas and a char; introducing the gas and the char into a slagging combustion furnace through a duct; melting ash contained in the gas and the char in said slagging combustion furnace while combusting the gas and the char at a temperature enough to melt the ash; discharging incombustibles through a discharge port from said gasification furnace and removing metals from the incombustibles discharged; crushing the incombustibles from which the metals are removed; and supplying the crushed incombustibles to said gasification furnace or said slagging combustion furnace or said duct.

2. A gasification and slagging combustion method according to claim 1, wherein after crushing the incombustibles, the crushed incombustibles are stored in a hopper .

3. A gasification and slagging combustion method according to claim 1, wherein the crushed incombustibles are supplied at a constant rate to said gasification furnace or said slagging combustion furnace or said duct.

4. A gasification and slagging combustion method according to claim 1, wherein the crushed incombustibles are supplied at a variable rate to said gasification furnace or said slagging combustion furnace or said duct.

5. A gasification and slagging combustion method according to claim 1, wherein the amount of the crushed incombustibles supplied to said gasification furnace or said slagging combustion furnace or said duct is adjusted so that a temperature in said slagging combustion furnace becomes 1200 °C or higher.

6. A gasification and slagging combustion method according to claim 1 , wherein an exhaust gas is discharged from said slagging combustion furnace and fly ash which is recovered from the exhaust gas is supplied to said gasification furnace or said slagging combustion furnace or said duct.

7. A gasification and slagging combustion apparatus for treating combustibles, comprising: a gasification furnace that gasifies combustibles to produce a gas and char, said gasification furnace having a discharge port for discharging incombustibles from said gasification furnace; a slagging combustion furnace that melts ash contained in the gas and the char produced by gasification while combusting the gas and the char at a temperature enough to melt the ash; a duct configured to supply the gas and the char from said gasification furnace into said slagging combustion furnace; a separating and classifying device configured to separate and classify the incombustibles discharged from said discharge port; a removing device configured to remove metals from the separated incombustibles; a crusher configured to crush the incombustibles from which metals are removed; and a supplying device configured to supply the crushed incombustibles to said gasification furnace or said slagging combustion furnace or said duct.

8. A gasification and slagging combustion apparatus according to claim 7, further comprising a hopper configured to store the crushed incombustibles after the incombustibles are crushed.

9. A gasification and slagging combustion apparatus according to claim 7, wherein said supplying device comprises a constant feeder configured to feed the crushed incombustibles at a constant rate.

10. A gasification and slagging combustion apparatus according to claim 7, wherein said supplying device comprises a variable feeder configured to feed the crushed incombustibles at a variable rate.

11. A gasification and slagging combustion apparatus according to claim 7, wherein said supplying device has a regulating device configured to adjust the amount of the crushed incombustibles supplied to said gasification furnace or said slagging combustion furnace or said duct so that a temperature in said slagging combustion furnace becomes 1200 °C or higher.

12. A gasification and slagging combustion apparatus according to claim 7, further comprising: a fly ash recovery device configured to recover fly ash from exhaust gas discharged from said slagging combustion furnace; and a fly ash supply device configured to supply the fly ash recovered by said fly ash recovery device to said gasification furnace or said slagging combustion furnace or said duct.