US20160257895A1

US20160257895A1 - Slag discharge apparatus and slag discharge method

Info

Publication number: US20160257895A1
Application number: US15/032,151
Authority: US
Inventors: Yasuo Soda; Yasuyuki Miyata; Yoshinori Koyama; Yasunari Shibata; Haruto Shinoda
Original assignee: Mitsubishi Hitachi Power Systems Ltd
Current assignee: Mitsubishi Power Ltd
Priority date: 2013-11-15
Filing date: 2014-09-10
Publication date: 2016-09-08
Also published as: KR20160064170A; KR101813419B1; KR20170077149A; WO2015072219A1; WO2016076379A1; JP2015117373A; CN105658772B; CN105658772A; US20170342337A1; CN107109262A

Abstract

The objective of the present invention is to facilitate passing of slag accumulated on a top face of a screen through openings in the screen. A combustor of a gasifier (10) that gasifies a carbonaceous feedstock is provided with a slag crusher (20) which discharges slag produced in and fallen from the combustor out of the gasifier (10). The slag crusher (20) comprises: a screen (22) which is provided transversely with respect to the fall direction of the slag and has a plurality of openings (30) to allow slag pieces that are smaller than the diameter of the openings (30) to pass through the screen (22); a spreader (24) which moves along the top face of the screen (22) and crushes the slag accumulated on the top face of the screen (22); and a nozzle (26) which spouts pressurized water onto the slag accumulated on the screen (22).

Description

TECHNICAL FIELD

The present invention relates to a slag discharge apparatus and a slag discharge method.

BACKGROUND ART

An ash hopper, in which slag (molten slag) produced in and falling from a combustor is collected, is provided in a lower portion of a gasifier which gasifies a carbonaceous feedstock such as coal (PTLs 1 and 2).
A slag crusher which includes a screen and a spreader is provided in the ash hopper. The slag falling from the combustor is rapidly cooled by water so as to be solidified, and falls on a top face of the screen included in the slag crusher.
The screen is provided transversely with respect to the fall direction of the slag and includes a plurality of openings. Accordingly, slag pieces which are smaller than diameters of the openings pass through the screen, and fall to the lower portion of the ash hopper.
Meanwhile, slag pieces which are larger than the diameters of the openings, or a slag lump which is an accumulation of the slag pieces which are smaller than the diameters of the openings are accumulated on the top face of the screen. In the slag lump, slag pieces are combined by a friction force in particle layers or cross-linking due to powder pressure.
Accordingly, for example, the spreader provided on the top face of the screen is moved along the top face of the screen by a hydraulic cylinder, and the spreader crushes the slag by applying the slag accumulated on the top face of the screen so as to allow the slag to pass through the screen.
The slag, which falls from the openings of the screen to the lower portion of the ash hopper and is accumulated, is discharged from the gasifier out of a system via a lock hopper.

CITATION LIST

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. H7-247484
[PTL 2] Japanese Unexamined Patent Application Publication No. H9-38510

SUMMARY OF INVENTION

Technical Problem

However, even when the spreader is operated, the accumulated slag may be not crushed, and the slag may not pass through the screen by only collecting the slag in the operating direction of the slag crusher.
In addition, an accumulation amount of the slag on the top face of the screen increases, the slag may not be discharged from the gasifier, and the inner portion of the ash hopper may be filled with the slag. In this case, the operation of the gasifier cannot be continued, and the gasifier is stopped.
The present invention is made in consideration of the above-described circumstances, and an object thereof is to provide a slag discharge apparatus and a slag discharge method capable of allowing the slag accumulated on the top face of the screen more easily to pass through the openings of the screen.

Solution to Problem

In order to solve the above-described problems, a slag discharge apparatus and a slag discharge method of the present invention adopt the following means.
According to a first aspect of the present invention, there is provided a slag discharge apparatus which is provided on a combustor of a gasifier gasifying a carbonaceous feedstock and discharges slag produced in and falling from the combustor out of the gasifier, comprising: a screen which is provided transversely with respect to the fall direction of the slag and has a plurality of openings to allow slag pieces which are smaller than diameters of the openings to pass through the screen; crushing means moving along a top face of the screen to crush the slag accumulated on the top face of the screen; and a spouting hole which spouts pressurized liquid onto the slag accumulated on the screen.
The slag discharge apparatus according to the present configuration is provided on a combustor of a gasifier gasifying the carbonaceous feedstock and discharges slag produced in and falling from the combustor out of the gasifier.
In addition, the slag discharge apparatus includes the screen which is provided transversely with respect to the fall direction of the slag and has the plurality of openings. The slag pieces, which are smaller than the diameters of the openings of the screen, pass through the openings so as to fall. Meanwhile, the slag, which does not pass through the openings and is accumulated on the top face of the screen, is crushed by the crushing means moving along the top face of the screen.
Here, the slag which is accumulated on the top face of the screen include a slag lump in which slag pieces smaller than the diameters of the openings are combined by a friction force or cross-linking due to powder pressure.
In order to remove the accumulated slag, the pressurized liquid is spouted from the spouting hole onto the slag accumulated on the top face of the screen. The combination due to the cross-linking is cut by spouting the pressurized liquid onto particles of the slag which are combined by the cross-linking. Accordingly, the slag is gently fluidized from a stationary state. In addition, for example, the liquid spouted onto the slag is water.
In addition, the slag which is easily fluidized is made to flow by the liquid spouted from the spouting hole. Accordingly, the slag falls along with the liquid from the openings of the screen without moving the crush means. In addition, the slag easily falls from the openings by moving the crushing means.
As described above, in the present configuration, the slag accumulated on the top face of the screen can easily be passed through the openings of the screen.
In the first aspect, preferably, the spouting hole is provided on a side wall of the screen which is erected in parallel with respect to an operating direction of the crushing means.
According to the present configuration, it is possible to easily and uniformly spout the pressurized liquid onto the accumulated slag.
In the first aspect, preferably, the spouting hole is provided in the crushing means.
According to the present configuration, since the pressurized liquid is more reliably spouted onto the slag crushed by the crushing means, it is possible to reliably crush the accumulated slag.
In the first aspect, preferably, the crushing means includes an inclined surface which is inclined forward with respect to a crushing direction of the slag.
According to the present configuration, since a downward force is applied to the accumulated slag, it is possible to more reliably crush the accumulated slag.
In the first aspect, preferably, the spouting hole is provided on the inclined surface, and spouts the liquid in the direction of the screen.
According to the present configuration, since the downward force is also added to the slag, which is crushed by the crushing means, due to the spouted liquid, it is possible to more reliably crush the accumulated slag.
In the first aspect, preferably, the spouting hole is provided in the screen.
According to the present configuration, it is possible to prevent the slag from being accumulated on the top face of the screen, and it is possible to easily and uniformly spout the pressurized liquid onto the accumulated slag.
In the first aspect, preferably, the spouting hole spouts gas instead of the liquid.
According to the present configuration, since gas is spouted from the top face of the screen in a state where the top face of the screen is filled with water, combination due to cross-linking of the slag is cut by rising of air bubbles. Accordingly, since the slag is fluidized, the slag accumulated on the top face of the screen more easily passes through the openings of the screen.
According to a second aspect of the present invention, there is provided a slag discharge method of using a slag discharge apparatus which is provided on a combustor of a gasifier gasifying a carbonaceous feedstock and discharges slag produced in and falling from the combustor out of the gasifier, comprising: a first step of spouting pressurized liquid from a spouting hole onto slag accumulated on a top face of a screen which is provided transversely with respect to the fall direction of the slag and has a plurality of openings; and a second step of moving crushing means for crushing the slag accumulated on the top face of the screen along the top face of the screen.

Advantageous Effects of Invention

According to the present invention, excellent effects are obtained in which slag accumulated on a top face of a screen can easily pass through openings of the screen.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal section view of a gasifier according to a first embodiment of the present invention.

FIG. 2 is a longitudinal section view of a slag crusher according to the first embodiment of the present invention.

FIG. 3 is a front view of a spreader according to the first embodiment of the present invention.

FIG. 4 is a longitudinal sectional view when a spreader according to a second embodiment of the present invention is viewed from a side.

FIG. 5 is a longitudinal sectional view when the spreader according to the second embodiment of the present invention is viewed from a front side.

FIG. 6 is a longitudinal section view of a screen according to a third embodiment of the present invention.

FIG. 7 is a longitudinal section view of a screen according to a modification example of the third embodiment of the present invention.

FIG. 8 is a longitudinal section view of a screen according to a fourth embodiment of the present invention.

FIG. 9 is a longitudinal section view of a screen according to a modification example of the fourth embodiment of the present invention.

FIG. 10 is a top view of a slag crusher according to a fifth embodiment of the present invention.

FIG. 11 is a longitudinal section view of a screen and a side wall according to the fifth embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of a slag discharge apparatus and a slag discharge method according to the present invention will be described with reference to the drawings.

First Embodiment

Hereinafter, a first embodiment of the present invention will be described.
FIG. 1 is a longitudinal section view of a gasifier 10 according to the first embodiment.
As carbonaceous feedstocks applied to the gasifier according to the first embodiment, there are wastes such as waste tires or plastics in addition to heavy fuels such as coal, petroleum coke, coal coke, asphalt, pitch, or oil shale. In the following embodiments, a case in which the gasified carbonaceous feedstock is coal will be described.
In the gasifier 10, pulverized coal which is supplied from a coal supply device (not shown) and char which is recovered by dedusting device (not shown) react with an oxidizing agent in a combustor 12 under a high temperature atmosphere of approximately 1500° C. to 1800° C. which is an ash melting point or more. Accordingly, when the pulverized coal is combusted at a high temperature in the combustor 12, coal gas which is combustible gas is generated, and slag 14 in which ash in the pulverized coal is melted is generated.
In addition, the high-temperature coal gas obtained by the high temperature combustion in the combustor 12 flows into a reductor 16 which is provided on the upper stage of the combustor 12. The pulverized coal and the char are also supplied to the reductor 16, the supplied pulverized coal and char are further gasified, and coal gas which is combustible gas is generated. In addition, the combustor 12 according to the first embodiment is an entrained bed type combustor. However, the combustor 12 is not limited to this, and may be a fluidized bed type combustor or a fixed bed type combustor.
An ash hopper 18, which collects the slag 14 produced in and falling from the combustor 12, is provided in the lower portion of the gasifier 10.
The ash hopper 18 is provided with a slag crusher 20 which crushes the slag 14 and discharges the slag out of the gasifier 10.
FIG. 2 is a longitudinal section view showing a configuration of the slag crusher 20 according to the first embodiment.
The slag crusher 20 is provided with a screen 22, a spreader 24, and a nozzle 26.
The slag 14 falling from the combustor 12 is rapidly cooled by water (hereinafter, referred to as “ash hopper water”) which is spouted from an ash hopper water-supply pipe 28 so as to be solidified, and the solidified slag falls to the top face of the screen 22 provided in the slag crusher 20.
The screen 22 with a plurality of openings 30 is provided transversely with respect to the fall direction of the slag 14, and slag pieces 14 which are smaller than diameters of the openings 30 pass through the screen. For example, the screen 22 is a plate-shaped member which includes the openings 30.
The slag 14 passing through the openings 30 falls to the lower portion of the ash hopper 18 along with the ash hopper water. As shown in FIG. 1, a lock hopper 34 is connected to the lower portion of the ash hopper 18, and the slag 14 falling to the lower portion of the ash hopper 18 is discharged out of the system via the lock hopper 34.
In addition, as an example, the gasifier 10 of FIG. 1 adopts a gravity falling method in which the slag 14 is discharged out of the system by making the slag 14 fall to the lock hopper 34. However, the present invention is not limited to this, and a horizontal suction method may be adopted in which the slag 14 is extracted so as to be reused without causing the slag 14 to fall to the lock hopper 34.
The spreader 24 is moved along the top face of the screen 22 by the hydraulic cylinder 36, and crushes the slag 14 accumulated on the top face of the screen 22. In addition, the position of the spreader 24 shown in FIG. 2 is a standby position before the spreader moves along the top face of the screen 22.
A receiving plate 38 is provided on a side opposite to the standby position of the spreader 24. That is, the spreader 24 moves from the standby position to the receiving plate 38, and the slag 14 accumulated on the top face of the screen 22 is collected. In addition, the slag 14 is interposed between the spreader 24 and the receiving plate 38, and the accumulated slag 14 is crushed. In addition, protrusion portions 40 are provided on a front surface of the spreader 24 so as to easily crush the slag 14.
In addition, the spreader 24 according to the first embodiment is provided with an inclined surface 24A which is inclined forward with respect to the crushing direction of the slag 14. The inclined surface 24A is provided on the lower portion of the spreader 24. The spreader 24 collects the accumulated slag 14 mainly by the inclined surface 24A. The portion above the inclined surface 24A becomes a perpendicular surface 24B perpendicular to the screen 22.
In addition, the nozzle 26 is a spouting hole which spouts pressurized liquid onto the slag 14 accumulated on the screen 22. The nozzle 26 according to the first embodiment is provided on the inclined surface 24A of the spreader 24. As shown in a front view of the spreader 24 of FIG. 3, for example, the plurality of nozzles 26 are horizontally provided on the inclined surface 24A.
For example, the pressurized liquid which is spouted from the nozzle 26 is water. However, the present invention is not limited to this, and the pressurized liquid may be liquid which can cut cross-linking of the slag 14 as described below. In addition, in descriptions below, the pressurized water is referred to as high pressure water. For example, the pressure of the high pressure water is 3 MPa to 5 MPa.
A water supply pipe 42, through which the high pressure water is supplied to the ash hopper water-supply pipe 28, is branched and connected to the nozzle 26. More specifically, the branched water supply pipe 42 is connected to a high pressure hose 44. The high pressure hose 44 has flexibility so as to correspond to the movement of the spreader 24, and is supported by a high pressure hose receiver 46.
The high pressure hose 44 is connected to a high pressure water header 48. The high pressure water header supplies the plurality of nozzles 26 with the high pressure water.
Next, an operation of the slag crusher 20 according to the first embodiment will be described.
The slag 14 generated in the combustor 12 falls on the top face of the screen 22.
In the slag 14 which falls on the top face of the screen 22, slag pieces 14 which are smaller than the diameters of the openings 30 of the screen 22 pass through the openings 30, and fall to the lower portion of the ash hopper 18, that is, the lower portion of the gasifier 10.
Meanwhile, slag pieces 14 which are larger than the diameters of the openings 30, or slag lumps which are accumulations of the slag pieces 14 which are smaller than the diameters of the openings 30 cannot pass through the openings 30, and are accumulated on the top face of the screen 22.
Accordingly, the spreader 24 moves from the standby position to the receiving plate 38 along the top face of the screen 22 every fixed time interval. Accordingly, the spreader 24 crushes the accumulated slag 14 such that the slag 14 easily passes through the openings 30.
In addition, since the spreader 24 according to the first embodiment applies a downward force to the accumulated slag 14 using the inclined surface 24A, the accumulated slag 14 can be more reliably crushed.
However, the slag lumps, in which small slag pieces 14 are combined by cross-linking, are not crushed by the spreader 24, do not pass through the openings 30, and may be collected in the movement direction of the spreader 24.
Accordingly, the high pressure water is spouted from the nozzles 26, which are provided on the inclined surface 24A of the spreader 24, toward the slag 14. Since the high pressure water is spouted to the particles of the slag 14 combined by cross-linking, the combination by cross-linking is cut. Accordingly, the slag 14 is gently fluidized from a stationary state.
In addition, since the nozzles 26 are provided on the inclined surface 24A, the high pressure water is more reliably spouted to the slag 14 which is crushed by the spreader 24. Accordingly, it is possible more reliably crush the accumulated slag 14.
Moreover, a time interval of the emission of the high pressure water from the nozzles 26 may be the same as a time interval of the movement of the spreader 24, or the emission of the high pressure water may be intermittently or continuously performed regardless of the time interval of the movement of the spreader 24.
In addition, the slag 14, which is easily fluidized, is made to flow by the high pressure water spouted from the nozzles 26. Accordingly, the slag 14 falls from the openings 30 of the screen 22 along with the high pressure water without moving the spreader 24. In addition, the slag 14 easily falls from the openings 30 even by moving spreader 24.
As described above, the slag crusher 20 according to the first embodiment is provided with the screen 22 which is provided transversely with respect to the fall direction of the slag 14 and has the plurality of openings to allow the slag pieces 14 which are smaller than diameters of the openings 30 to pass through the screen, the spreader 24 which moves along the top face of the screen 22 to crush the slag 14 accumulated on the top face of the screen 22, and the nozzles 26 which spouts the high pressure water onto the slag 14 accumulated on the screen 22.
Accordingly, the slag crusher 20 causes the slag 14 accumulated on the top face of the screen 22 to more easily pass through the openings 30 of the screen 22. Therefore, even when the slag 14 is accumulated on the top face of the screen 22, it is possible to more reliably discharge the slag 14 by the slag crusher 20. As a result, it is possible to prevent the operation of the gasifier 10 from being stopped due to accumulation of the slag 14, and a continuous operation of the gasifier 10 can be performed.
Moreover, in the slag crusher 20 according to the first embodiment, the nozzles 26 are provided on the inclined surface 24A of the spreader 24. However, the present invention is not limited to this, and the nozzles 26 may be provided on the perpendicular surface 24B of the spreader 24.

Second Embodiment

Hereinafter, a second embodiment of the present invention will be described.
Since the configuration of the gasifier 10 according to the second embodiment is the same as the configuration of the gasifier 10 according to the first embodiment shown in FIG. 1, descriptions thereof are omitted.
FIG. 4 is a longitudinal sectional view when the spreader 24 according to the second embodiment is viewed from a side. FIG. 5 is a longitudinal sectional view when the spreader 24 according to the second embodiment is viewed from a front side, and is a section view taken along A-A in FIG. 4. In addition, in FIGS. 4 and 5, the same reference numerals as those of FIGS. 2 and 3 are assigned to the same configuration portions as those of FIGS. 2 and 3, and descriptions thereof are omitted.
The nozzles 26 according to the second embodiment are provided on the inclined surface 24A, and spouts high pressure water in the direction of the screen 22.
For example, a header 50 is provided in the inner portion of the spreader 24. The plurality of nozzles 26 facing downward are connected to the header 50, and the high pressure water is spouted from the nozzles 26 to the top face of the screen 22. Moreover, the time interval of the emission of the high pressure water from the nozzles 26 may be the same as the time interval of the movement of the spreader 24, or the emission of the high pressure water may be intermittently or continuously performed regardless of the time interval of the movement of the spreader 24. In addition, when the high pressure water header 48 is provided in the slag crusher 20, the header 50 may not be provided.
Accordingly, in the slag crusher 20 according to the second embodiment, since the downward force is applied to the slag 14, which is crushed by the spreader 24, by the high pressure water, it is possible to more reliably crush the accumulated slag 14.

Third Embodiment

Hereinafter, a third embodiment of the present invention will be described.
Since the configuration of the gasifier 10 according to the third embodiment is the same as the configuration of the gasifier 10 according to the first embodiment shown in FIG. 1, descriptions thereof are omitted.
In the slag crusher 20 according to the third embodiment, nozzles 60 which spouts high pressure water are provided in the screen 22.
FIG. 6 is an example of a longitudinal section view of the screen 22 according to the third embodiment of the present invention.
In the example of FIG. 6, the nozzles 60, to which the high pressure water is supplied via headers 62, are provided on the side surface of the openings 30 of the screen 22. The water supply pipe 42, through which the high pressure water is supplied to the ash hopper water-supply pipe 28, is branched, and is connected to the header 62.
FIG. 7 is a longitudinal section view of the screen according to a modification example of the third embodiment.
In the example of FIG. 7, the nozzles 60, to which the high pressure water is supplied via the headers 62, are provided on the top face of the screen 22.
In addition, the time interval of the emission of the high pressure water from the nozzles 60 may be the same as the time interval of the movement of the spreader 24, or the emission of the high pressure water may be intermittently or continuously performed regardless of the time interval of the movement of the spreader 24.
In the slag crusher 20 according to the third embodiment, since the high pressure water is spouted to particles of the slag 14 combined by cross-linking, the combination by the cross-linking is cut. Accordingly, the accumulated slag 14 is easily fluidized.
Moreover, since the pressure water is spouted from the lower portion of the screen 22 toward the upper portion, it is possible to prevent the slag 14 from being accumulated on the top face of the screen 22, and it is possible to easily and uniformly spout the pressurized liquid to the accumulated slag 14.

Fourth Embodiment

Hereinafter, a fourth embodiment of the present invention will be described.
Since the configuration of the gasifier 10 according to the fourth embodiment is the same as the configuration of the gasifier 10 according to the first embodiment shown in FIG. 1, descriptions thereof are omitted.
FIGS. 8 and 9 are longitudinal section views of the screen 22 according to the fourth embodiment. In addition, in FIGS. 8 and 9, the same reference numerals as those of FIGS. 6 and 7 are assigned to the same configuration portions as those of FIGS. 6 and 7, and descriptions thereof are omitted.
In this screen 22 according to the fourth embodiment, high pressure gas (hereinafter, referred to as “high pressure gas”) instead of the high pressure water is spouted from the nozzles 60. Accordingly, the headers 62 are connected to the high pressure gas supply pipe 42 through which the high pressure gas is supplied.
Moreover, the time interval of the emission of the high pressure gas from the nozzles 60 may be the same as the time interval of the movement of the spreader 24, or the emission of the high pressure gas may be intermittently or continuously performed regardless of the time interval of the movement of the spreader 24.
Due to the high pressure water spouted from the nozzles 60 provided in the spreader 24 or the water from the ash hopper water-supply pipe 28, the top face of the screen 22 is filled with water.
In addition, in the slag crusher 20 according to the fourth embodiment, since the gas is spouted from the top face of the screen 22 in the state where the top face of the screen 22 is filled with water, air bubbles of the high pressure gas rise from the top face of the screen 22. The combination of the slag 14 by cross-linking is cut by the rising of the air bubbles. Accordingly, since the slag 14 is fluidized, the slag 14 accumulated on the top face of the screen 22 more easily passes through the openings 30 of the screen 22.

Fifth Embodiment

Hereinafter, a fifth embodiment of the present invention will be described.
Since the configuration of the gasifier 10 according to the fifth embodiment is the same as the configuration of the gasifier 10 according to the first embodiment shown in FIG. 1, descriptions thereof are omitted.
FIG. 10 is a top view of the slag crusher 20 according to the fifth embodiment.
FIG. 11 is a longitudinal section view of the screen 22 and side walls 70 according to the fifth embodiment, and is a sectional view taken along A-A in FIG. 10. In addition, in FIGS. 10 and 11, the same reference numerals as those of FIGS. 2 and 3 are assigned to the same configuration portions as those of FIGS. 2 and 3, and descriptions thereof are omitted.
The slag crusher 20 according to the fifth embodiment includes nozzles 72 which spout high pressure water at the side walls 70 of the screen 22 which are erected in parallel with respect to the operation direction of the spreader 24.
As shown in FIG. 11, for example, the nozzles 72 are provided in the lower portions of the side walls 70.
In the slag crusher 20 according to the fifth embodiment, it is possible to easily and uniformly spout the high pressure water to the accumulated slag 14. In addition, since the nozzles 72 are provided on the side walls 70, it is possible to easily install the nozzles 70 on the slag crusher 20.
In addition, the high pressure water spouted from the nozzles 72 may be also used as the ash hopper water.
Hereinbefore, the present invention is described using the embodiments. However, the technical scope of the present invention is not limited to the scope described in the embodiments. Various modifications or improvements are added to the embodiments within a scope which does not depart from the gist of the present invention, and aspects to which modifications or improvements are added are also included in the technical scope of the present invention. In addition, the plurality of embodiments may be combined.
For example, in the embodiments, the aspect in which the spreader 24 moves toward the receiving plate 38 is described. However, the present invention is not limited to this, and an aspect may be adopted in which the spreader 24 is provided instead of the receiving plate 38 and a pair of spreaders 24 moves along the top face of the screen 22 to crush the slag 14.

REFERENCE SIGNS LIST

- 10: gasifier
- 12: combustor
- 14: slag
- 20: slag crusher
- 22: screen
- 24: spreader
- 24A: inclined surface
- 26: nozzle
- 30: opening
- 60: nozzle
- 70: side wall
- 72: nozzle

Claims

1-8. (canceled)

9. A slag discharge device which is provided on a combustor of a gasifier gasifying a carbon containing fuel and discharges slag produced in and falling from the combustor out of the gasifier, comprising:

a screen which is provided transversely with respect to the fall direction of the slag and has a plurality of openings to allow slag pieces which are smaller than diameters of the openings to pass through the screen;

crushing means moving along a top face of the screen to crush the slag accumulated on the top face of the screen; and

an emitting hole which emits liquid, which is pressurized, fluidizes the slag accumulated on the screen, and allows the slag to pass through the openings, onto the slag.

10. The slag discharge device according to claim 9,

wherein the emitting hole is provided on a side wall of the screen which is erected in parallel with respect to an operating direction of the crushing means.

11. The slag discharge device according to claim 9,

wherein the emitting hole is provided in the crushing means.

12. The slag discharge device according to claim 9,

wherein the crushing means includes an inclined surface which is inclined forward with respect to a crushing direction of the slag.

13. The slag discharge device according to claim 12,

wherein the emitting hole is provided on the inclined surface, and emits the liquid in the direction of the screen.

14. The slag discharge device according to claim 9,

wherein the emitting hole is provided in the screen.

15. The slag discharge device according to claim 14,

wherein the emitting hole emits gas instead of the liquid.

16. A slag discharge method of using a slag discharge device which is provided on a combustor of a gasifier gasifying a carbon containing fuel and discharges slag produced in and falling from the combustor out of the gasifier, comprising:

a first step of emitting liquid, which is pressurized from an emitting hole, fluidizes the slag, and causes the slag to pass through a plurality of openings, onto the slag accumulated on a top face of a screen which is provided transversely with respect to the fall direction of the slag and has the plurality of openings; and

a second step of moving crushing means for crushing the slag accumulated on the top face of the screen along the top face of the screen.