JP7039793B2 - How to stop the slag discharge system, slag discharge system and gasification combined cycle - Google Patents

Description

The present invention relates to a method for stopping a slag emission system, a slag emission system and a gasification combined power generation device applicable to a gasification furnace for gasifying carbon-containing solid fuel such as coal.

Conventionally, as a gasification furnace facility, carbon-containing solid fuel such as coal is supplied into the gasification furnace, and the carbon-containing solid fuel is partially combusted and gasified to generate combustible gas. Equipment (coal gasification equipment) is known.

In a gasification furnace that gasifies biomass fuel such as coal and wood pellets and carbon-containing solid fuel such as pet cork, the ash content of the carbon-containing solid fuel melts and accumulates as slag in the slag hopper provided below the gasification furnace. do. Slag water (cooling water) is stored in the slag hopper, and the slag falls into the slag water and is rapidly cooled to solidify and crush it.

The slag that has been solidified and crushed in this way and accumulated in the slag hopper is discharged to the outside of the gasification furnace system via the lock hopper provided outside the gasification furnace. Since slag has a higher density than slag water, in the past, when moving slag from the slag hopper to the rock hopper, it was naturally dropped by gravity. For example, Patent Document 1 discloses a slag discharge system in which a lock hopper is arranged below a gasification furnace.

However, according to the above-mentioned slag discharge system, when the slag is naturally dropped by gravity, the position of the gasifier is higher because the lock hopper is provided on the vertically lower side of the gasifier. Therefore, the height from the installation surface of the plant to the upper part of the gasification furnace will increase. As the arrangement position of the gasification furnace becomes high, the arrangement position of the support pedestal and the operation pedestal supporting the gasification furnace becomes high, and there is a problem that the cost required for the installation work of the gasification furnace becomes high.

Therefore, a slag discharge system as disclosed in Patent Document 2 has been proposed. In this slag discharge system, the lock hopper is placed on the side of the gasifier, a slag discharge line that connects the slag hopper to the lock hopper is provided, and a circulation pump forms a water flow from the slag hopper to the lock hopper in the slag discharge line. However, the slag in the slag hopper is discharged to the lock hopper by this water flow.

Further, in the gasification apparatus disclosed in Patent Document 3, when the gasification furnace is stopped, the pressure in the gasification furnace is increased and decreased in order to purge the generated gas remaining in the gasification furnace. By fluctuating, a gas flow is generated in the gasification furnace, and the generated gas flow is used to carry it out of the gasification furnace.

Japanese Unexamined Patent Publication No. 2011-74274 Japanese Patent No. 5743093 JP-A-2017-95635

In the slag discharge system disclosed in Patent Document 2, since the lock hopper is arranged on the side of the gasifier, a line that guides the slag from the bottom of the gasifier to the top of the lock hopper when discharging the slag. It is necessary to form a water stream.
However, when the generated gas disclosed in Patent Document 3 is purged when the gasification furnace is stopped, the pressure in the gasification furnace after the completion of the purge does not increase (near the atmospheric pressure). Therefore, when the line leading the slag from the bottom of the gasification furnace to the top of the lock hopper is filled with water, the pressure due to the head difference becomes higher than the pressure in the gasification furnace after the completion of purging, and gasification occurs. No water flow can be formed in the line leading the slag from the bottom of the furnace to the top of the lock hopper. Therefore, the residue after purging cannot be guided from the bottom of the gasifier to the top of the lock hopper by hydraulic transport.

The present invention has been made in view of this situation, and even after the slag discharge line is stopped, the residue such as char remaining in the slag hopper is transported to the slag separation device via the slag discharge line. It is an object of the present invention to provide a method of stopping a slag discharge system that can be processed, a slag discharge system and a gasification composite power generation device.

In order to solve the above problems, the following means are adopted for the slag discharge system stop method, the slag discharge system and the gasification combined cycle device.
That is, the method for stopping the slag discharge system according to one aspect of the present invention is provided on the vertically lower side of the gasification furnace for gasifying the carbon-containing solid fuel, and cooling water for cooling the slag falling in the gasification furnace. A slag hopper in which gas is stored, a slag separation device that separates the slag from a mixture of the slag and the cooling water, and a first on-off valve are provided, and a slag discharge line that guides the mixture from the slag hopper to the slag separation device. A cooling water circulation line provided with a second on-off valve and returning the cooling water separated by the slag separation device to the slag hopper, and a circulation pump provided downstream of the second on-off valve in the cooling water circulation line. A method of stopping a slag discharge system including a bypass line for guiding a part of the cooling water in the slag hopper to the cooling water circulation line between the second on-off valve and the circulation pump. The third position in the vertical direction at the downstream end of the slag discharge line is higher than the first position in the vertical direction of the valve and the second position in the vertical direction of the second on-off valve, and the first on-off valve and the second on-off valve are higher. The gasification is performed from a state in which the on-off valve is closed and the pressure of the gas in the gasification furnace is smaller than the water head differential pressure between the first position and the second position and the third position. After the stop pressurization step of pressurizing the pressure in the furnace to a predetermined pressure larger than the slag differential pressure and the stop pressurization step, the first on-off valve and the second on-off valve are opened. Includes connection process.

The method for stopping the slag discharge system according to this embodiment is a third position in the vertical direction at the downstream end of the slag discharge line, rather than a first position in the vertical direction of the first on-off valve and a second position in the vertical direction of the second on-off valve. A predetermined pressure that is high in position, the first on-off valve and the second on-off valve are closed, and the pressure of the gas in the gasifier is smaller than the water head differential pressure between the first and second positions and the third position. After the stop pressurization step of pressurizing the pressure in the gasification furnace to a predetermined pressure larger than the head differential pressure and the stop pressurization step, the first on-off valve and the second on-off valve are opened. Including the connection process. According to this, after the slag discharge system is stopped, the slag hopper and the slag separation device can be connected by maintaining the pressure in the gasification furnace rising to a predetermined pressure larger than the head differential pressure. As a result, even after the slag discharge system is stopped, the residue such as char remaining in the slag hopper can be transported to the slag separation device for processing via the slag discharge line. Therefore, the step of removing the residue in the slag hopper in the periodic inspection performed after the gasification furnace is stopped is shortened. If the pressure in the gasifier remains lower than the head differential pressure after the slag discharge system is shut down (when the pressure in the gasifier is low), the slag hopper and slag separator cannot be connected. The residue in the slag hopper cannot be transported to the slag separator. In addition, "connecting" here does not mean connecting devices mechanically (for example, simply connecting devices by piping), but the water held in a certain system can be circulated and hydropower can be transported. Say to be in a state.
Further, in the above-mentioned case, the pressure in the gasification furnace is maintained high even after the slag discharge system is stopped. When introducing the inert gas used for pressurizing the gasifier into the gasifier, for example, the inert gas has the effect of becoming a cooling gas for cooling the gasifier, so pressurize the gasifier. It is possible to increase the weight flow rate of the inert gas as the cooling gas as compared with the case where the gas is not used. Therefore, since the amount of heat that the inert gas as the cooling gas can absorb from the gasification furnace increases, the cooling performance by the inert gas as the cooling gas is improved.

Further, in the method for stopping the slag discharge system according to one aspect of the present invention, the pressure of the gas in the gasification furnace is reduced to a predetermined pressure smaller than the head differential pressure before the stop pressurization step. However, the shutoff step of closing the first on-off valve and the second on-off valve is included.

In the method of stopping the slag discharge system according to this embodiment, the first on-off valve and the first on-off valve and the first on-off valve are reduced to a predetermined pressure smaller than the head differential pressure before the stop pressurization step. The shutoff step of closing the second on-off valve is included. According to this, for example, immediately after the gasification furnace equipment is stopped, even if the pressure inside the gasification furnace is high due to the generated gas, the pressure inside the gasification furnace is reduced to a predetermined pressure smaller than the head differential pressure. The first on-off valve and the second on-off valve can be closed. As a result, the slag discharge line and the cooling water circulation line are separated into the vertical upper system of the first on-off valve and the second on-off valve (high head system) and the vertical upper system of the first on-off valve and the second on-off valve (low). It can be separated from the water head system).

Further, in the method for stopping the slag discharge system according to one aspect of the present invention, the cooling water is circulated between the slag hopper and the cooling water circulation line via the bypass line by the blocking step. The pressure in the gasification furnace is smaller than the head differential pressure. Within a predetermined range of the predetermined pressure, depressurization and pressurization are repeated at least once, and the generated gas remaining in the gasification furnace is discharged to the gasification furnace. Including a swing purging step of discharging to the outside of.

In the method of stopping the slag discharge system according to this embodiment, the pressure in the gasification furnace is higher than the head differential pressure while the cooling water is circulated between the slag hopper and the cooling water circulation line via the bypass line by the shutoff step. It also includes a swing purging step of repeating depressurization and pressurization at least once within a predetermined range of a small predetermined pressure to discharge the produced gas remaining in the gasifier to the outside of the gasifier. According to this, the gas remaining in the gasification furnace is efficiently discharged to the outside of the gasification furnace by performing the swing purge, and the chars remaining in the gasification furnace due to the depressurization in the gasification furnace are discharged. It can be dropped into a slug hopper.

Further, in the method for stopping the slag discharge system according to one aspect of the present invention, the depressurization in the swing purging step reduces the pressure in the gasification furnace to normal pressure.

In the method of stopping the slag discharge system according to this embodiment, the depressurization in the swing purge step reduces the pressure in the gasification furnace to the normal pressure. According to this, the generated gas remaining in the gasification furnace can be efficiently discharged to the outside of the gasification furnace and replaced with the inert gas.

Further, the slag discharge system according to one aspect of the present invention is provided vertically below the gasification furnace for gasifying carbon-containing solid fuel, and stores cooling water for cooling the slag falling in the gasification furnace. A slag hopper, a slag separation device that separates the slag from a mixture of the slag and the cooling water, a slag discharge line that is provided with a first on-off valve and guides the mixture from the slag hopper to the slag separation device, and a first A cooling water circulation line provided with two on-off valves and returning the cooling water separated by the slag separation device to the slag hopper, a circulation pump provided downstream of the second on-off valve in the cooling water circulation line, and the slag hopper. A bypass line for guiding a part of the cooling water in the cooling water to the cooling water circulation line between the second on-off valve and the circulation pump is provided, and the first position in the vertical direction of the first on-off valve and the second on-off valve are provided. The third position in the vertical direction at the downstream end of the slag discharge line is higher than the second position in the vertical direction of the on-off valve, the first on-off valve and the second on-off valve are closed, and the gasifier. The pressure in the gasification furnace is larger than the water head differential pressure from the state of the predetermined pressure where the pressure of the gas in the gas is smaller than the water head differential pressure between the first position and the second position and the third position. It is provided with a control unit that pressurizes the pressure to a predetermined pressure and then opens the first on-off valve and the second on-off valve.

According to the slag discharge system according to the main body aspect, even if the residue such as char remains in the slag hopper after the slag discharge line is stopped, the residue in the slag hopper is transported to the slag separator via the slag discharge line. Can provide a slag discharge system that can be processed.

Further, the gasification combined power generation device according to one aspect of the present invention includes the slag emission system, a gas turbine that is rotationally driven by burning at least a part of the generated gas generated in the gasifier, and the gas. It includes a steam turbine that is rotationally driven by steam generated by an exhaust heat recovery boiler that introduces turbine exhaust gas discharged from the turbine, and a generator connected to the rotating shaft of the gas turbine and / or the steam turbine.

According to the gasification combined cycle device according to the main body aspect, even if the residue such as char remains in the slag hopper after the slag discharge line is stopped, the residue in the slag hopper can be used as the slag separation device via the slag discharge line. A slag emission system that can be transported and processed can be provided.

According to the present invention, even after the slag discharge line is stopped, the residue such as char remaining in the slag hopper can be transported to the slag separation device for treatment through the slag discharge line.

It is a schematic block diagram of the coal gasification combined cycle power generation facility to which the gasification furnace facility which concerns on one Embodiment of this invention is applied. It is a schematic block diagram of the gasification furnace equipment shown in FIG. It is a time-pressure diagram showing the relationship between the pressure in the gasification furnace and the elapsed time when the gasification furnace equipment according to the embodiment of the present invention is stopped.

Hereinafter, an embodiment of the gasification furnace facility (slag discharge system) according to the present invention will be described with reference to FIGS. 1 to 3.
FIG. 1 is a schematic configuration diagram of an integrated coal gasification combined cycle facility 10 to which the gasification furnace facility 14 according to the embodiment of the present invention is applied.

The integrated coal gasification combined cycle (IGCC) 10 to which the gasification combined cycle facility 14 according to the present embodiment is applied is used as an oxidizing agent mainly containing air, and is used in the gasification combined cycle facility 14. , Adopts an air combustion method that generates flammable gas (generated gas) from fuel. Then, the integrated coal gasification combined cycle facility 10 purifies the generated gas generated in the gasification furnace facility 14 into a fuel gas by the gas refining facility 16 and then supplies the gas to the gas turbine 17 to generate power. That is, the integrated coal gasification combined cycle facility 10 of the present embodiment is an air combustion type (air blown) power generation facility. As the fuel to be supplied to the gasification furnace facility 14, for example, a carbon-containing solid fuel such as coal is used.

As shown in FIG. 1, the integrated coal gasification combined cycle facility (gasification combined cycle facility) 10 includes a coal supply facility 11, a gasification furnace facility 14, a char recovery facility 15, a gas purification facility 16, and a gas turbine. It includes 17, a steam turbine 18, a generator 19, and an exhaust heat recovery steam generator (HRSG: Heat Recovery Steam Generator) 20.

The coal supply facility 11 is supplied with coal, which is a carbon-containing solid fuel, as raw coal, and crushes the coal with a coal mill (not shown) to produce pulverized coal pulverized into fine particles. The pulverized coal produced in the coal supply facility 11 is pressurized by nitrogen gas as a transport inertia gas supplied from the air separation facility 42 described later at the outlet of the coal supply line 11a, and is directed toward the gasifier facility 14. Will be supplied. The Inert gas is an inert gas having an oxygen content of about 5% by volume or less, and nitrogen gas, carbon dioxide gas, argon gas and the like are typical examples, but the gas content is not necessarily limited to about 5% or less.

In the gasification furnace facility 14, pulverized coal produced by the coal supply facility 11 is supplied, and the char (unreacted coal and ash) recovered by the char recovery facility 15 is supplied for reuse. There is.

Further, a compressed air supply line 41 from the gas turbine 17 (compressor 61) is connected to the gasification furnace equipment 14, and a part of the compressed air compressed by the gas turbine 17 is pressured by the booster 68. It is boosted to the gas turbine equipment 14 and can be supplied to the gas turbine equipment 14. The air separation facility 42 separates and generates nitrogen and oxygen from the air in the atmosphere, and the air separation facility 42 and the gasifier facility 14 are connected by a first nitrogen supply line 43. A coal supply line 11a from the coal supply facility 11 is connected to the first nitrogen supply line 43.

Further, the second nitrogen supply line 45 branching from the first nitrogen supply line 43 is also connected to the gasifier facility 14, and the char return line 46 from the char recovery facility 15 is connected to the second nitrogen supply line 45. It is connected. Further, the air separation equipment 42 is connected to the compressed air supply line 41 by an oxygen supply line 47. Then, the nitrogen separated by the air separation facility 42 is used as a transport gas for coal or char by flowing through the first nitrogen supply line 43 and the second nitrogen supply line 45. Further, the oxygen separated by the air separation facility 42 is used as an oxidant in the gasifier facility 14 by flowing through the oxygen supply line 47 and the compressed air supply line 41.

The gasifier facility 14 includes, for example, a two-stage jet bed type gasifier 101 (see FIG. 2). The gasification furnace facility 14 gasifies the coal (pulverized coal) and char supplied to the inside by partially burning them with an oxidizing agent (air, oxygen) to obtain a produced gas. The gasification furnace facility 14 is provided with a foreign matter removing facility 48 for removing foreign matter (molten slag (hereinafter, also simply referred to as slag)) mixed in the pulverized coal. A gas generation line 49 for supplying the generated gas to the char recovery equipment 15 is connected to the gasifier facility 14, so that the generated gas containing the char can be discharged. In this case, as shown in FIG. 2, by providing a thin gas cooler 102 (gas cooler) in the gas generation line 49, the generated gas may be cooled to a predetermined temperature and then supplied to the char recovery equipment 15.

The char collection facility 15 includes a dust collector facility 51 and a supply hopper 52. In this case, the dust collecting facility 51 is composed of one or a plurality of cyclones or porous filters, and can separate the char contained in the generated gas generated by the gasifier facility 14. Then, the generated gas from which the char is separated is sent to the gas refining facility 16 through the gas discharge line 53. The supply hopper 52 stores the char separated from the generated gas by the dust collector 51. A bin may be arranged between the dust collector 51 and the supply hopper 52, and a plurality of supply hoppers 52 may be connected to the bin. Then, the char return line 46 from the supply hopper 52 is connected to the second nitrogen supply line 45.

The gas refining facility 16 purifies the produced gas from which the char is separated by the char recovery facility 15 by removing impurities such as sulfur compounds and nitrogen compounds. Then, the gas refining facility 16 purifies the produced gas to produce a fuel gas, which is supplied to the gas turbine 17. Since the produced gas from which the char is separated still contains sulfur ( _H2S , etc.), the gas refining equipment 16 removes and recovers the sulfur content with an amine absorber or the like for effective use. do.

The gas turbine 17 includes a compressor 61, a combustor 62, and a turbine 63, and the compressor 61 and the turbine 63 are connected by a rotating shaft 64. A compressed air supply line 65 from the compressor 61 is connected to the combustor 62, a fuel gas supply line 66 from the gas refining facility 16 is connected to the combustor 62, and a combustion gas supply line 67 extending toward the turbine 63 is connected. Is connected. Further, the gas turbine 17 is provided with a compressed air supply line 41 extending from the compressor 61 to the gasifier equipment 14, and a booster 68 is provided in the middle of the gas turbine 17. Therefore, in the combustor 62, a part of the compressed air supplied from the compressor 61 and at least a part of the fuel gas supplied from the gas purification facility 16 are mixed and burned to generate and burn the combustion gas. The generated combustion gas is supplied to the turbine 63. Then, the turbine 63 rotationally drives the generator 19 by rotationally driving the rotary shaft 64 with the supplied combustion gas.

The steam turbine 18 includes a turbine 69 connected to a rotary shaft 64 of a gas turbine 17, and a generator 19 is connected to a base end portion of the rotary shaft 64. The exhaust heat recovery boiler 20 is connected to the exhaust gas line 70 from the gas turbine 17 (turbine 63), and steam is exchanged between the water supplied to the exhaust heat recovery boiler 20 and the exhaust gas of the turbine 63. Is to generate. The exhaust heat recovery boiler 20 is provided with a steam supply line 71 and a steam recovery line 72 between the exhaust heat recovery boiler 20 and the turbine 69 of the steam turbine 18, and a condenser 73 is provided on the steam recovery line 72. Further, the steam generated by the exhaust heat recovery boiler 20 may include steam generated by heat exchange with the generated gas in the thin gas cooler 102 of the gasification furnace 101 (see FIG. 2). Therefore, in the steam turbine 18, the turbine 69 is rotationally driven by the steam supplied from the exhaust heat recovery boiler 20, and the generator 19 is rotationally driven by rotating the rotary shaft 64.

A gas purification facility 74 is provided from the outlet of the exhaust heat recovery boiler 20 to the chimney 75.
Here, the operation of the integrated coal gasification combined cycle facility 10 of the present embodiment will be described.

In the integrated coal gasification combined cycle facility 10 of the present embodiment, when raw coal (coal) is supplied to the coal supply facility 11, the coal is pulverized into fine particles in the coal supply facility 11 to become pulverized coal. .. The pulverized coal produced in the coal supply facility 11 is supplied to the gasifier facility 14 through the first nitrogen supply line 43 by the nitrogen supplied from the air separation facility 42. Further, the char recovered by the char recovery facility 15 described later is circulated through the second nitrogen supply line 45 by the nitrogen supplied from the air separation facility 42 and supplied to the gasifier facility 14. Further, the compressed air extracted from the gas turbine 17 described later is boosted by the booster 68, and then supplied to the gasifier facility 14 through the compressed air supply line 41 together with the oxygen supplied from the air separation facility 42.

In the gasification furnace facility 14, the supplied pulverized coal and char are burned by compressed air (oxygen), and the pulverized coal and char are gasified to generate a produced gas. Then, this generated gas is discharged from the gasification furnace facility 14 through the gas generation line 49 and sent to the char recovery facility 15.

In the char recovery equipment 15, the generated gas is first supplied to the dust collecting equipment 51, so that fine chars contained in the generated gas are separated. Then, the generated gas from which the char is separated is sent to the gas refining facility 16 through the gas discharge line 53. On the other hand, the fine char separated from the generated gas is deposited on the supply hopper 52, returned to the gasifier facility 14 through the char return line 46, and recycled.

The generated gas from which the char is separated by the char recovery facility 15 is gas refined by removing impurities such as sulfur compounds and nitrogen compounds in the gas refining facility 16 to produce a fuel gas. The compressor 61 generates compressed air and supplies it to the combustor 62. The combustor 62 mixes the compressed air supplied from the compressor 61 and the fuel gas supplied from the gas refining facility 16 and burns them to generate combustion gas. By rotationally driving the turbine 63 with this combustion gas, the compressor 61 and the generator 19 are rotationally driven via the rotating shaft 64. In this way, the gas turbine 17 can generate electricity.

Then, the exhaust heat recovery boiler 20 generates steam by exchanging heat between the exhaust gas discharged from the turbine 63 in the gas turbine 17 and the water supplied to the exhaust heat recovery boiler 20, and the generated steam is used in the steam turbine 18. Supply to. In the steam turbine 18, the turbine 69 is rotationally driven by the steam supplied from the exhaust heat recovery boiler 20, so that the generator 19 can be rotationally driven via the rotary shaft 64 to generate electricity.
The gas turbine 17 and the steam turbine 18 do not have to rotate drive one generator 19 on the same axis, and may rotate drive a plurality of generators on different axes.

After that, in the gas purification equipment 74, harmful substances of the exhaust gas discharged from the exhaust heat recovery boiler 20 are removed, and the purified exhaust gas is discharged from the chimney 75 to the atmosphere.

Next, the gasifier equipment 14 shown in FIG. 1 will be described with reference to FIG.
As shown in FIG. 2, the gasification furnace equipment 14 of the present embodiment includes a gasification furnace 101, a foreign matter removal equipment 48, a slag discharge line 140, a cooling water circulation line 150, a circulation pump 160, and a cooler 170. A bypass line 210, a first on-off valve 180, a second on-off valve 190, and a control unit 90 are provided.

Hereinafter, each configuration included in the gasification furnace equipment 14 will be described.
Here, in each equipment shown in FIG. 2, other configurations (foreign matter removing equipment 48, slag discharge line 140, cooling water circulation line 150, circulation pump 160, cooler) other than the gasifier 101 included in the gasifier equipment 14 170, bypass line 210, first on-off valve 180, second on-off valve 190, control unit 90, etc.) are the slag discharge systems of the present embodiment. The gasification furnace equipment 14 of the present embodiment includes a gasification furnace 101 and a slag discharge system.

The gasification furnace 101 is formed to extend in the vertical direction (direction extending upward along the axis X orthogonal to the installation surface S), and pulverized coal and oxygen are supplied to the lower side in the vertical direction to perform partial combustion (partial combustion (direction extending upward along the axis X orthogonal to the installation surface S). The generated gas that has been gasified by pyrolysis) is flowing from the lower side in the vertical direction to the upper side. The gasifier 101 has a pressure vessel 110 and a gasifier wall (furnace wall) 111 provided inside the pressure vessel 110. The gasifier 101 forms an annulus portion 115 in the space between the pressure vessel 110 and the gasifier wall 111. Further, in the space inside the gasification furnace wall 111, the gasifier 101 has a converter section 116, a diffuser section 117, and a reducer section 118 in order from the lower side in the vertical direction (that is, the upstream side in the flow direction of the generated gas). Is forming.

The pressure vessel 110 is formed in a tubular shape having a hollow space inside, and a gas discharge port 121 is formed at the upper end portion, while a slug hopper 122 is formed at the lower end portion (bottom portion). The gasification furnace wall 111 is formed in a tubular shape having a hollow space inside, and the wall surface thereof is provided so as to face the inner surface of the pressure vessel 110. In the present embodiment, the pressure vessel 110 is formed in a cylindrical shape, and the diffuser portion 117 of the gasification furnace wall 111 is also formed in a cylindrical shape. The gasification furnace wall 111 is connected to the inner surface of the pressure vessel 110 by a support member (not shown).

The gasification furnace wall 111 has a shape in which the cross-sectional shape changes at the diffuser portion 117 between the converter portion 116 and the reducer portion 118. The upper end of the gasification furnace wall 111 is connected to the gas discharge port 121 of the pressure vessel 110, and the lower end of the vertical direction is provided with a gap from the bottom of the pressure vessel 110. Cooling water (reservoir) is stored in the slag hopper 122 formed below the pressure vessel 110, and the cooling water flows into the lower end of the gasification furnace wall 111, so that the gasification furnace wall 111 The inside and outside are sealed. A burner 126 and a burner 127 are inserted into the gasification furnace wall 111, and a singus cooler 102 is arranged in the internal space of the gasification furnace wall 111.

The annular portion 115 is a space formed inside the pressure vessel 110 and outside the gasification furnace wall 111, and in the present embodiment, nitrogen, which is an inert gas separated by the air separation equipment 42, is a nitrogen supply line ( It is supplied through (not shown). Therefore, the annulus portion 115 becomes a space filled with nitrogen. In the vicinity of the upper part of the annulus portion 115 in the vertical direction, an in-core pressure equalizing pipe (not shown) for equalizing the pressure inside the gasification furnace 101 is provided. The pressure equalizing pipe in the furnace is provided so as to communicate the inside and outside of the gasification furnace wall 111, and the pressure between the inside of the gasification furnace wall 111 (combustor section 116, diffuser section 117 and reducer section 118) and the outside (annulus section 115). The pressure is approximately equalized so that the difference is within a predetermined pressure.

The pressure sensor 128 is a sensor that detects the pressure inside the gasifier 101 (pressure vessel 110). The pressure sensor 128 is electrically connected to the control unit 90, and the pressure detected by the pressure sensor 128 is transmitted to the control unit 90.

The control unit 90 is composed of, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. As an example, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program, and the CPU reads this program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, is provided in a state of being stored in a computer-readable storage medium, or is distributed via a wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

The combustor section 116 is a space for partially burning pulverized coal, char, and air, and a combustion device composed of a plurality of burners 126 is arranged on the gasification furnace wall 111 of the combustor section 116. The high-temperature combustion gas that burns the pulverized coal and a part of the char in the combustor section 116 passes through the diffuser section 117 and flows into the reducer section 118.

The reducer section 118 is maintained at a high temperature state required for the gasification reaction, supplies pulverized coal to the combustion gas from the convertor section 116 and partially burns the pulverized coal to volatile components (carbon monoxide, hydrogen, lower hydrocarbons, etc.). ), Which is a space to generate gasified generated gas. A combustion device composed of a plurality of burners 127 is arranged on the gasification furnace wall 111 in the reducer portion 118.

The slag hopper 122 is a device provided vertically below the gasification furnace 101 to receive slag (molten slag) generated in high-temperature gas by combustion of pulverized coal and char, and to store cooling water for cooling the slag. be. The slag is solidified and crushed by falling into the cooling water stored in the slag hopper 122 and being rapidly cooled. The crushed slag accumulates in the bottom 122A of the slag hopper 122.

The thin gas cooler 102 is provided inside the gasification furnace wall 111, and is provided on the upper side of the burner 127 of the reducer portion 118 in the vertical direction. The sink gas cooler 102 is a heat exchanger, and the evaporator (evaporator) 131, the superheater (superheater) 132, and the node are in order from the lower side in the vertical direction (upstream side in the flow direction of the generated gas) of the gasification furnace wall 111. A coal device (economizer) 134 is arranged. These thin gas coolers 102 cool the generated gas by exchanging heat with the generated gas generated in the reducer portion 118. Further, the number of the evaporator (evaporator) 131, the superheater (super heater) 132, and the economizer (economizer) 134 is not limited to the quantity shown in the figure.

Here, the operation of the above-mentioned gasification furnace 101 will be described.
In the gasification furnace 101, nitrogen and pulverized coal are charged and ignited by the burner 127 of the reducer unit 118, and pulverized coal, char and compressed air (oxygen) are charged and ignited by the burner 126 of the combustor unit 116. .. Then, in the combustor section 116, high-temperature combustion gas is generated by combustion of pulverized coal and char. Further, in the combustor section 116, molten slag is generated in high-temperature gas by combustion of pulverized coal and char, and the molten slag adheres to the gasification furnace wall 111 and falls to the bottom of the furnace, and finally in the slag hopper 122. It is discharged to the cooling water of. Then, the high-temperature combustion gas generated in the converter section 116 passes through the diffuser section 117 and rises to the reducer section 118. In this reducer portion 118, the pulverized coal is maintained at the high temperature state required for the gasification reaction, mixed with the high temperature combustion gas, and the pulverized coal is partially burned (pyrolyzed) in a high temperature reducing atmosphere to gasify. The reaction is carried out and the produced gas is produced. The gasified generated gas flows from the lower side in the vertical direction to the upper side.

The foreign matter removing facility 48 is a facility for removing slag mixed from a mixture of slag and cooling water discharged from the slag hopper 122 by the slag discharge line 140, and is a cyclone (slag separating device) 48A, a lock hopper 48B, and storage. It includes a tank 48C, a sluice valve 48D, a first discharge valve 48E, and a second discharge valve 48F.

The cyclone 48A is a device that separates slag from a mixture of slag and cooling water by centrifugal force. In addition, instead of the cyclone 48A, a filtration type slag separation device such as a strainer or a filter may be used. The cyclone 48A separates the slag from the mixture supplied from the slag discharge line 140, which will be described later, to the intake port 48Aa, and guides the slag vertically downward. Further, the cyclone 48A separates the cooling water from the mixture of the slag and the cooling water, and discharges the cooling water from the discharge port 48Ab to the cooling water circulation line 150 described later.

The lock hopper 48B is a hopper that stores a predetermined amount of slag separated by the cyclone 48A. The slag separated by the cyclone 48A is supplied to the lock hopper 48B when the sluice valve 48D is in the open state. When the slag is accumulated in the lock hopper 48B in a predetermined amount or for a predetermined period, the sluice valve 48D is closed, and the first discharge valve 48E is opened after the depressurization operation is performed. The slag stored in the lock hopper 48B falls into the storage tank 48C by gravity in response to the opening of the first discharge valve 48E.

The storage tank 48C is a device that receives and stores the slag stored in the lock hopper 48B and discharges the stored slag to the transport vehicle C. The slag stored in the storage tank 48C is discharged to the transport vehicle C when the second discharge valve 48F is in the open state. The slag discharged to the transport vehicle C is transported to the outside of the gasifier equipment 14.

The slag discharge line 140 is a pipe that guides a mixture of slag and cooling water from the bottom 122A of the slag hopper 122 to the cyclone 48A. The slag discharge line 140 is provided with a first on-off valve 180 that switches between a distribution state in which the mixture flows and a cutoff state in which the flow of the mixture is blocked.
The slag discharge line 140 is arranged on the upstream side slag discharge line 140A arranged on the upstream side in the flow direction of the mixture from the first on-off valve 180 and on the downstream side in the flow direction of the mixture from the first on-off valve 180. It has a downstream slag discharge line 140B.

At the upstream end of the upstream slag discharge line 140A, an intake port 141 arranged in the vicinity of the bottom portion 122A of the slag hopper 122 is provided. The slag accumulated in the bottom portion 122A of the slag hopper 122 flows into the upstream slag discharge line 140A from the intake port 141 together with the surrounding cooling water by the action of the water flow generated by the circulation pump 160 described later. The mixture of slag and cooling water discharged from the upstream slag discharge line 140A is guided to the downstream slag discharge line 140B and flows into the cyclone 48A from the intake port 48Aa.

Here, the mixture of slag and cooling water is not naturally dropped from the slag hopper 122 by gravity and transferred to the cyclone 48A, but is transferred by a water flow flowing through the slag discharge line 140. Therefore, the cyclone 48A can be arranged not vertically downward but on the side of the gasifier 101, and the height position of the gasifier 101 can be suppressed so as not to be high.

The cooling water circulation line 150 is a pipe that returns the cooling water separated by the cyclone 48A and discharged from the discharge port 48Ab to the slug hopper 122. The cooling water circulation line 150 includes a circulation pump 160, a cooler 170 for cooling the cooling water returned to the slug hopper 122, and a second opening / closing state for switching between a distribution state in which the cooling water flows and a cutoff state in which the circulation of the cooling water is cut off. A valve 190 and a valve 190 are provided. The cooling water circulation line 150 is arranged on the upstream side cooling water circulation line 150A arranged on the upstream side in the cooling water flow direction from the second on-off valve 190 and on the downstream side in the cooling water flow direction from the second on-off valve 190. It has a downstream cooling water circulation line 150B.

The circulation pump 160 is a pump that guides a mixture of slag and cooling water from the slag hopper 122 to the cyclone 48A and forms a water flow that returns the cooling water from the cyclone 48A to the slag hopper 122. The circulation pump 160 forms the above-mentioned water flow by operating the slag discharge line 140 and the cooling water circulation line 150 in a state where the mixture or the cooling water is filled.

The bypass line 210 is a pipe that guides the cooling water stored in the slug hopper 122 to the downstream cooling water circulation line 150B arranged on the downstream side of the second on-off valve 190. The bypass line 210 is provided with a third on-off valve 220.
The circulation pump 160 of the present embodiment is arranged in the cooling water circulation line 150 on the downstream side in the cooling water flow direction from the confluence position M where the cooling water is guided from the bypass line 210 to the downstream cooling water circulation line 150B.

Since the circulation pump 160 is located downstream of the confluence position M in the flow direction of the cooling water, the cooling stored in the slug hopper 122 even when the first on-off valve 180 and the second on-off valve 190 are closed. Water can be circulated. That is, by operating the circulation pump 160, in the present embodiment, the cooling water can be circulated in the order of the slug hopper 122, the third on-off valve 220, the circulation pump 160, and the cooler 170.

The control unit 90 is a device that controls each part of the gasification furnace equipment 14, and is, for example, a first on-off valve 180, a second on-off valve 190, a third on-off valve 220, a sluice valve 48D, a first discharge valve 48E, and a first. 2 Controls the open / closed state of the discharge valve 48F. Further, the control unit 90 controls, for example, the discharge amount of the circulation pump 160.

In FIG. 2, the first position P1 shown on the axis X is a height position in the vertical direction in which the first on-off valve 180 is arranged. Further, the second position P2 shown on the axis X is a height position in the vertical direction in which the second on-off valve 190 is arranged. Further, the third position P3 shown on the axis X is a vertical height position arranged at the downstream end of the slag discharge line 140 that supplies the mixture to the cyclone 48A. The first position P1, the second position P2, and the third position P3 each indicate the height in the vertical direction in the axis X direction with respect to the installation surface S. As shown in FIG. 2, the height position of the third position P3 in the vertical direction is higher than that of the first position P1 and the second position P2.

The water surface of the cooling water stored in the slag hopper 122 causes the cooling water to flow into the lower end of the gasification furnace wall 111 to seal the inside and outside of the gasification furnace wall 111 and discharge the slag to the vertically upper part of the gasification furnace 101. It is necessary to maintain an appropriate height so that the system holding water of the line 140 and the cooling water circulation line 150 does not flow in. FIG. 2 shows a state in which the water surface of the cooling water is maintained at the position P0 by the pressure in the pressure vessel 110. When the pressure in the pressure vessel 110 is low, the system holding water flows in due to the pressure due to the head difference between the first position P1 and the second position P2 and the third position P3.

In the slag discharge system 14, the portion of the slag hopper 122 installed at a height vertically below the water surface position P0 of the cooling water is the low head system L, and is at a height vertically above the position P0. The part installed in is the high head system H.
The low head system L is a system including an upstream slag discharge line 140A and a downstream cooling water circulation line 150B. On the other hand, the high head system H is a system including a downstream slag discharge line 140B and an upstream cooling water circulation line 150A.
In order to maintain the high head system H, a pressure in the pressure vessel 110 that is higher than the pressure due to the head difference between the first position P1 and the second position P2 and the third position P3 is required.

In the present embodiment, the first position P1 in which the first on-off valve 180 is arranged and the second position P2 in which the second on-off valve 190 is arranged coincide with the position P0 on the water surface of the cooling water. Therefore, by closing the first on-off valve 180 and the second on-off valve 190, the low head system L and the high head system H can be separated.

Next, a method of stopping the gasification furnace facility (slag discharge system) 14 of the present embodiment will be described with reference to FIG.
Immediately after the gasification furnace equipment 14 is stopped (t1), the pressure in the gasification furnace 101 (pressure vessel 110) is set to the operating pressure Pr by the internal pressure of the generated gas generated in the gasification furnace 101. This operating pressure Pr is equal to or higher than the pressure due to the head difference between the first position P1 and the second position P2 and the third position P3 (hereinafter, simply referred to as "head differential pressure Ph"). Therefore, the cooling water circulates between the low head system L and the high head system H.

In the process of shutting down the gasifier equipment 14, the pressure of the pressure vessel 110 is reduced from the state of the operating pressure Pr to a predetermined pressure lower than the head differential pressure Ph (for example, normal pressure in this embodiment). The depressurization is generated in the pressure vessel 110 from a blow valve (not shown) connected to the gasification furnace 101 by stopping the gas supplied to the gasification furnace 101 such as the coal supply facility 11 and the oxygen supply line 47. It is carried out by discharging the gas to the gas generation line 49. The blow valve is electrically connected to the control unit 90, and its opening degree is controlled by the control unit 90. The worker may manually adjust the opening degree.

When the depressurization progresses and the pressure in the pressure vessel 110 detected by the pressure sensor 128 approaches the head differential pressure Ph, the third on-off valve 220 is opened by the control unit 90 while the circulation pump 160 is operating. .. After that, the first on-off valve 180 and the second on-off valve 190 are closed by the control unit 90 (cutoff step). The time when the pressure is close to the head differential pressure Ph is when a pressure having a certain margin with respect to the head differential pressure Ph (a pressure higher than the head differential pressure Ph) is reached, for example, the head differential pressure. It is when the pressure reaches about 10% higher than Ph. The range of this pressure can be appropriately changed depending on the specifications and operating conditions of the gasifier equipment 14.
After the shutoff step, when the depressurization progresses further and the pressure equal to or higher than the head differential pressure Ph cannot be maintained (t2), that is, when the high head system H cannot be maintained, the first on-off valve 180 and the first on-off valve 180 and the first on-off valve are not maintained by the shutoff step. 2 Since the on-off valve 190 is in the closed state, the water flow by the circulation pump 160 is formed so as to circulate only in the low head system L. That is, when the inside of the gasifier 101 is not pressurized to the head differential pressure Ph or higher, the slug hopper 122, the bypass line 210, a part of the downstream cooling water circulation line 150B, the circulation pump 160 and the cooler 170 are circulated. A stream of water is formed.

After switching from the circulation including the high head system H to the circulation containing only the low head system L, swing purging is performed in order to easily discharge the generated gas containing char and the like remaining in the pressure vessel 110 (swing purge step). ). Swing purging is to efficiently discharge the generated gas containing char and the like remaining in the pressure vessel 110 to the outside of the pressure vessel 110 by repeating pressurization and depressurization in the pressure vessel 110 at least once. Is. This also has the effect of preventing the generated gas containing toxic components such as CO gas from remaining in the gasification furnace 101 during periodic inspections when workers enter the gasification furnace 101. The pressurization is performed by injecting an inert gas such as nitrogen into the pressure vessel 110 from an injection unit (not shown) connected to the gasification furnace 101. The injection unit is electrically connected to the control unit 90, and the flow rate of the inert gas injected into the pressure vessel 110 is controlled by the control unit 90.

In the swing purge, the pressure in the pressure vessel 110 is set to a predetermined pressure lower than the head differential pressure Ph in the stop depressurizing step, and is reduced to, for example, normal pressure Po in the present embodiment (t3). The "normal pressure" referred to here is a pressure of about atmospheric pressure, for example, a pressure of about 0.1 MPa or more, but may be a pressure sufficiently lower than the head differential pressure Ph. After reducing the pressure in the pressure vessel 110 to the normal pressure Po, the pressure in the pressure vessel 110 is pressurized. Pressurization is performed until the swing purge pressure Pp, which is a predetermined value equal to or less than the head differential pressure Ph, is reached. This swing purge is performed in the range of normal pressure Po or more and head differential pressure Ph or less (swing purge pressure Pp), and is executed by repeating the cycle of depressurization and pressurization at least once. For example, in the present embodiment, the time required for one cycle is selected so that the generated gas remaining in the pressure vessel 110 can be efficiently discharged to the other outside, and is preferably within about 60 minutes.

In the present embodiment, after the swing purge is completed (t4), the first on-off valve 180 and the second on-off valve 190 are in the closed state, and the pressure in the gasifier 101 is a predetermined pressure smaller than the head differential pressure Ph. From the state, pressure is applied so that the pressure in the pressure vessel 110 reaches a predetermined pressure equal to or higher than the head differential pressure Ph (pressurization step at stop). The predetermined pressure equal to or higher than the head differential pressure Ph is a pressure having a certain margin with respect to the head differential pressure Ph (pressure higher than the head differential pressure Ph), and is, for example, about 10% higher than the head differential pressure Ph. It's pressure. The range of this pressure can be appropriately changed depending on the specifications and operating conditions of the gasifier equipment 14. After the pressure sensor 128 detects that the pressure in the pressure vessel 110 is pressurized to a predetermined pressure equal to or higher than the head differential pressure Ph (t5), the first on-off valve 180 and the second on-off valve 190 are controlled by the control unit 90. It is in the open state (connection process). Further, the third on-off valve 220 is closed by the control unit 90. Thereby, the low head system L and the high head system H can be connected, and the water flow by the circulation pump 160 is formed in the low head system L and the high head system H.

After the circulation of the cooling water in the high head system H is established, the cooling of the gasifier 101 is started. For cooling, an inert gas such as nitrogen is injected into the gasification furnace 101, and at the same time, the same amount of inert gas (heat exchanged in the gasifier 101) as the injected inert gas is gas. This is done by discharging from the chemical furnace 101. At this time, the pressure in the gasification furnace 101 is maintained in a pressurized state (Ph in FIG. 3). The injection and discharge of the inert gas are performed by the above-mentioned injection section (not shown) and the vent valve (not shown), respectively.

According to this embodiment, the following effects are obtained.
After the gasification furnace equipment (slag discharge system) 14 is stopped, the pressure in the gasification furnace 101 is maintained at the head differential pressure Ph or higher, so that the circulation by the high head system H is possible. That is, the slag hopper 122 and the cyclone (slag separation device) 48A can be connected. As a result, even after the slag discharge system 14 is stopped, the residue such as char remaining in the slag hopper 122 can be transported to the slag separation device 48A for processing via the slag discharge line 140. Therefore, the step of removing the residue in the slag hopper 122 in the periodic inspection performed after the gasification furnace equipment 14 is stopped is shortened.
Further, in the above-mentioned case, after the slag discharge system 14 is stopped, the pressure in the gasification furnace 101 becomes equal to or higher than the head differential pressure Ph. When introducing a gas (inert gas such as nitrogen) used for pressurizing the gasifier 101 into the gasifier 101, for example, the gas used for pressurization (inert gas such as nitrogen) is the gasifier 101. Since the effect of serving as a cooling gas for cooling the gas is obtained, the weight flow rate of the inert gas serving as the cooling gas can be increased as compared with the case where the gasifier 101 is not pressurized. Therefore, since the amount of heat that the inert gas as the cooling gas can absorb from the gasifier 101 increases, the cooling performance by the inert gas as the cooling gas is improved.
Further, by performing the swing purge, the generated gas remaining in the gasification furnace 101 is efficiently discharged to the outside of the gasification furnace 101, and the char remaining in the gasification furnace 101 due to the decompression in the gasification furnace 101. Etc. can be dropped onto the slug hopper 122. After the swing purge, the low head system L and the high head system H are connected, so that the residue that has fallen to the slag hopper 122 can be transported to the slag separation device 48A, and the residue can be treated.

Further, in the above-described embodiment, coal is used as the fuel, but other carbon-containing solid fuels such as high-grade coal and low-grade coal can also be applied, and the present invention is not limited to coal and is a renewable organism. Biomass used as an organic resource of origin may be used, for example, thinned wood, waste wood, drifting wood, grass, waste, sludge, tires, and recycled fuel (pellets and chips) made from these. It is also possible to use it.

Further, in the present embodiment, the tower type gasification furnace has been described as the gasification furnace 101, but the gasification furnace 101 generates vertical vertical directions of each device in the gasification furnace 101 even in the crossover type gasification furnace. The same can be achieved by replacing the gas so as to match the gas flow direction.

10 Integrated coal gasification combined cycle equipment (gasification combined cycle equipment)
14 Gasification furnace equipment (slag discharge system)
19 Generator 48 Foreign matter removal equipment 48A Cyclone (slag separator)
48Aa Intake port 48Ab Outlet port 48B Lock hopper 48C Storage tank 48D Partition valve 48E First discharge valve 48F Second discharge valve 49 Gas generation line 90 Control unit 101 Gasification furnace 102 Thin gas cooler 110 Pressure vessel 111 Gasification furnace wall (furnace) Wall)
115 Annulus 116 Convaster 117 Diffuser 118 Reducer 121 Gas outlet 122 Slug hopper 122A Bottom 126, 127 Burner 128 Pressure sensor (pressure detector)
131 Evaporator (evaporator)
132 Superheater (super heater)
134 Economizer
140 Slag discharge line 140A Upstream slag discharge line 140B Downstream slag discharge line 141 Intake port 150 Cooling water circulation line 150A Upstream cooling water circulation line 150B Downstream cooling water circulation line 160 Circulation pump 170 Cooler 180 First on-off valve 190 Second open / close Valve 210 Bypass line 220 Third on-off valve C Transport vehicle S Installation surface X Axis line

Claims (6)

A slag hopper provided vertically below the gasification furnace for gasifying carbon-containing solid fuel and storing cooling water for cooling the slag falling in the gasification furnace.
A slag separating device that separates the slag from a mixture of the slag and the cooling water,
A slag discharge line is provided with a first on-off valve to guide the mixture from the slag hopper to the slag separator.
A cooling water circulation line provided with a second on-off valve and returning the cooling water separated by the slag separator to the slag hopper,
In the cooling water circulation line, a circulation pump provided downstream of the second on-off valve and
A bypass line that guides a part of the cooling water in the slug hopper to the cooling water circulation line between the second on-off valve and the circulation pump.
Is a method of stopping the slag discharge system equipped with
The third position in the vertical direction at the downstream end of the slag discharge line is higher than the first position in the vertical direction of the first on-off valve and the second position in the vertical direction of the second on-off valve.
Predetermined that the first on-off valve and the second on-off valve are in the closed state, and the pressure of the gas in the gasifier is smaller than the head differential pressure between the first position and the second position and the third position. Pressurization step at stop to pressurize the pressure in the gasification furnace to a predetermined pressure larger than the head differential pressure from the pressure state of
After the stop pressurization step, a connection step of opening the first on-off valve and the second on-off valve, and a connection step of opening the second on-off valve.
How to stop the slag discharge system, including. Prior to the stop pressurization step, the first on-off valve and the second on-off valve are closed while reducing the pressure of the gas in the gasification furnace to a predetermined pressure smaller than the head differential pressure. The method for stopping the slag discharge system according to claim 1, further comprising a shutoff step. A predetermined pressure in which the pressure in the gasification furnace is smaller than the head differential pressure while the cooling water is circulated between the slag hopper and the cooling water circulation line through the bypass line by the shutoff step. The slag discharge according to claim 2, further comprising a swing purging step of discharging the generated gas remaining in the gasification furnace to the outside of the gasification furnace by repeating depressurization and pressurization at least once within the predetermined range of the above. How to stop the system. The method for stopping the slag discharge system according to claim 3, wherein the depressurization in the swing purge step reduces the pressure in the gasification furnace to normal pressure. A slag hopper provided vertically below the gasification furnace for gasifying carbon-containing solid fuel and storing cooling water for cooling the slag falling in the gasification furnace.
A slag separating device that separates the slag from a mixture of the slag and the cooling water,
A slag discharge line is provided with a first on-off valve to guide the mixture from the slag hopper to the slag separator.
A cooling water circulation line provided with a second on-off valve and returning the cooling water separated by the slag separator to the slag hopper,
In the cooling water circulation line, a circulation pump provided downstream of the second on-off valve and
A bypass line that guides a part of the cooling water in the slug hopper to the cooling water circulation line between the second on-off valve and the circulation pump.
Equipped with
The third position in the vertical direction at the downstream end of the slag discharge line is higher than the first position in the vertical direction of the first on-off valve and the second position in the vertical direction of the second on-off valve.
Predetermined that the first on-off valve and the second on-off valve are in the closed state, and the pressure of the gas in the gasifier is smaller than the head differential pressure between the first position and the second position and the third position. It is provided with a control unit which pressurizes the pressure in the gasification furnace to a predetermined pressure larger than the head differential pressure from the pressure state of the above, and then opens the first on-off valve and the second on-off valve. Slug discharge system. The slag discharge system according to claim 5 and
A gas turbine that is rotationally driven by burning at least a part of the generated gas generated in the gasification furnace, and
A steam turbine that is rotationally driven by steam generated by an exhaust heat recovery steam that introduces turbine exhaust gas discharged from the gas turbine, and
With a generator connected to the rotating shaft of the gas turbine and / or the steam turbine,
Gasification combined cycle.

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