JP2019131718A - Stop method of slag discharge system, slag discharge system and gasification composite power generator - Google Patents

Abstract

To provide a stop method of a slag discharge system, a slag discharge system, and a gasification composite power generator capable of transporting and treating a residual material such as a char, residing in a slag hopper to a slag separation apparatus via a slag discharge line even after stopping the slag discharge line.SOLUTION: The method includes: an on-stop pressurizing step, wherein, from a state of a third position P3 of a slag discharge line 140 in its vertical direction in its downstream end being higher than a first position P1 of a first on-off valve 180 in its vertical direction and a second position P2 of a second on-off valve 190 in its vertical direction, the first on-off valve 180 and the second on-off valve 190 being closed, and, a predetermined pressure state of a gas pressure in a gasification furnace 101 being smaller than a water head differential pressure between the first position P1 and the second position P2, and the third position P3, the pressure in the gasification furnace 101 is pressurized to a predetermined pressure which is larger than the water head differential pressure; and after the on-stop pressurizing step, a connection step, wherein the first on-off valve 180 and the second on-off valve 190 are made to be in open states.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for stopping a slag discharge system, a slag discharge system, and a combined gasification power generator that can be applied to a gasification furnace that gasifies carbon-containing solid fuel such as coal.

  Conventionally, as a gasifier facility, carbon-containing fuel gasification that generates combustible gas by supplying carbon-containing solid fuel such as coal into the gasifier and partially combusting the carbon-containing solid fuel for gasification Equipment (coal gasification equipment) is known.

  In gasification furnaces that gasify biomass fuels such as coal and wood pellets, and carbon-containing solid fuels such as pet coke, the ash content of the carbon-containing solid fuel melts and accumulates as slag in the slag hopper provided below the gasifier. To do. Slag water (cooling water) is stored in the slag hopper, and the slag is solidified and crushed by falling into the slag water and being rapidly cooled.

  The slag thus solidified and crushed and collected in the slag hopper is discharged out of the gasification furnace through a lock hopper provided outside the gasification furnace. Since slag has a higher density than slag water, conventionally, when slag was moved from the slag hopper to the lock hopper, it was naturally dropped by gravity. For example, Patent Document 1 discloses a slag discharge system in which a lock hopper is disposed below a gasification furnace.

  However, according to the slag discharge system described above, when the slag is naturally dropped by gravity, the arrangement position of the gasification furnace is increased because the lock hopper is provided on the vertically lower side of the gasification furnace. Therefore, the height from the plant installation surface to the upper part of the gasifier increases. As the gasification furnace is disposed at a higher position, the positions of the support frame, the operation frame, and the like that support the gasification furnace are increased, and there is a problem in that the cost for installing the gasification furnace is increased.

  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 gasification furnace, a slag discharge line communicating from the slag hopper to the lock hopper is provided, and a water flow from the slag hopper to the lock hopper is formed in the slag discharge line by a circulation pump The slag in the slag hopper is discharged to the lock hopper by this water flow.

  Further, in the gasifier disclosed in Patent Document 3, when the gasifier is stopped, in order to purge the generated gas remaining in the gasifier, the pressure in the gasifier is increased and decreased. The gas flow is generated in the gasification furnace by changing the gas flow rate, and is transported out of the gasification furnace by the generated gas flow.

JP 2011-74274 A Japanese Patent No. 574393 JP 2017-95635 A

In the slag discharge system disclosed in Patent Document 2, since the lock hopper is disposed on the side of the gasification furnace, a line for guiding the slag from the bottom of the gasification furnace to the top of the lock hopper when discharging the slag. It is necessary to form a water flow.
However, when purging the product gas disclosed in Patent Document 3 when stopping the gasification furnace, the pressure in the gasification furnace after purging is not increased (near atmospheric pressure). For this reason, 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 water head difference is greater than the pressure in the gasification furnace after the purge is completed. A water flow cannot be formed in the line leading the slag from the bottom of the furnace to the top of the lock hopper. Accordingly, the purged residue cannot be guided from the bottom of the gasification furnace to the top of the lock hopper by hydraulic transportation.

  The present invention has been made in view of this situation, and transports residues such as char remaining in the slag hopper to the slag separation device via the slag discharge line even after the slag discharge line is stopped. It aims at providing the stop method of the slag discharge system which can be processed, the slag discharge system, and the gasification combined cycle power generation device.

In order to solve the above-mentioned problems, a method for stopping a slag discharge system, a slag discharge system, and a combined gasification power generator employ the following means.
That is, the method for stopping a slag discharge system according to one aspect of the present invention is a cooling water that is provided vertically below a gasification furnace that gasifies carbon-containing solid fuel and cools slag falling in the gasification furnace. A slag hopper, a slag separator for separating the slag from the mixture of the slag and the cooling water, and a first on-off valve, and a slag discharge line for guiding 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 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 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 slag discharge system is stopped in a vertical direction at a downstream end of the slag discharge line from 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. The third position is high, the first on-off valve and the second on-off valve are closed, and the gas pressure in the gasification furnace is the head of the first position, the second position, and the third position. From a state of a predetermined pressure smaller than the differential pressure, after the stop pressurizing step of pressurizing the pressure in the gasifier to a predetermined pressure larger than the head differential pressure, after the stop pressurizing step, A connecting step of opening the first on-off valve and the second on-off valve.

The method for stopping the slag discharge system according to this aspect is a third method in the vertical direction at the downstream end of the slag discharge line, rather 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. A predetermined pressure that is high, the first on-off valve and the second on-off valve are closed, and the gas pressure in the gasifier is smaller than the water head differential pressure between the first position, the second position, and the third position. After the stop, the first on-off valve and the second on-off valve are opened after the stop-time pressurization step for pressurizing the pressure in the gasification furnace to a predetermined pressure larger than the water head differential pressure. And a connecting step. According to this, after the slag discharge system is stopped, the slag hopper and the slag separation device can be connected by raising the pressure in the gasification furnace to a predetermined pressure larger than the water head differential pressure. As a result, even after the slag discharge system is stopped, residues such as char remaining in the slag hopper can be transported to the slag separation device and processed through the slag discharge line. Therefore, the process 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 stopped (if the pressure in the gasifier is low), the slag hopper cannot be connected to the slag separator. The residue in the slag hopper cannot be transported to the slag separator. Note that “connecting” here does not mean that the devices are mechanically connected (for example, simply connecting the devices by piping), but the retained water in a certain system can be circulated and hydraulic transportation is possible. Say to be in a state.
In the above-described case, the pressure in the gasifier is maintained high after the slag discharge system is stopped. In introducing the inert gas used for pressurization of the gasification furnace into the gasification furnace, for example, the inert gas has an effect of becoming a cooling gas for cooling the gasification furnace. The weight flow rate of the inert gas serving as the cooling gas can be increased as compared with the case where it is not. Therefore, the amount of heat that can be absorbed from the gasification furnace by the inert gas serving as the cooling gas increases, so that the cooling performance by the inert gas serving 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 gas pressure in the gasification furnace is reduced to a predetermined pressure smaller than the water head differential pressure before the pressurizing step at the time of stop. On the other hand, it includes a shutoff step for closing the first on-off valve and the second on-off valve.

  The method for stopping the slag discharge system according to the present aspect includes the first on-off valve and the first on-off valve while reducing the pressure of the gas in the gasification furnace to a predetermined pressure lower than the water head differential pressure before the pressurizing step at the time of stop. A blocking step of closing the second on-off valve; According to this, for example, immediately after the gasification furnace equipment is stopped, even if the pressure in the gasification furnace is high due to the generated gas, while reducing the pressure in the gasification furnace to a predetermined pressure smaller than the water 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 connected to the system vertically above the first on-off valve and the second on-off valve (high head system) and to the system above the vertical direction of the first on-off valve and the second on-off valve (low It can be separated from the hydrohead 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 gasifier is reduced at least once within a predetermined range of the predetermined pressure, which is smaller than the water head differential pressure, and the product gas remaining in the gasifier is removed from the gasifier. Including a swing purge step of discharging to the outside.

  In the method for stopping the slag discharge system according to this aspect, the pressure in the gasifier 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 process. A swing purge step of discharging the product gas remaining in the gasification furnace to the outside of the gasification furnace by repeating depressurization and pressurization at least once within a predetermined range of a small predetermined pressure. According to this, by performing swing purge, the gas remaining in the gasification furnace is efficiently discharged to the outside of the gasification furnace, and the char remaining in the gasification furnace is reduced by the reduced pressure in the gasification furnace. Can be dropped into a slag hopper.

  In the method for stopping a slag discharge system according to one aspect of the present invention, the pressure in the swing purge step is to reduce the pressure in the gasification furnace to normal pressure.

  In the method for stopping the slag discharge system according to this aspect, the pressure reduction in the swing purge step is to reduce the pressure in the gasifier to normal pressure. According to this, the generated gas remaining in the gasification furnace can be efficiently discharged outside the gasification furnace and replaced with the inert gas.

  The slag discharge system according to one aspect of the present invention is provided on a vertically lower side of a gasification furnace that gasifies the carbon-containing solid fuel, and stores cooling water for cooling the slag falling in the gasification furnace. A slag hopper, a slag separator that separates the slag from the mixture of the slag and the cooling water, a first on-off valve, and a slag discharge line that guides the mixture from the slag hopper to the slag separator; 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 circulation line between the second on-off valve and the circulation pump, The third position in the vertical direction of 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. From the state where the second on-off valve is closed and the gas pressure in the gasification furnace is lower than the first position and the water head differential pressure between the second position and the third position, A control unit is provided that pressurizes the pressure in the gasification furnace to a predetermined pressure larger than the water head differential 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 mode, even if char or other residue remains in the slag hopper after the slag discharge line stops, the residue in the slag hopper is transported to the slag separation device via the slag discharge line. A slag discharge system that can be disposed of.

  Further, a combined gasification power generation device according to an aspect of the present invention includes the above-described slag discharge system, a gas turbine that is rotationally driven by burning at least a part of the generated gas generated in the gasification furnace, and the gas 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 that is coupled to the rotation shaft of the gas turbine and / or the steam turbine.

  According to the combined gasification power generation device according to the main body aspect, even if char residue or the like remains in the slag hopper after the slag discharge line is stopped, the residue in the slag hopper is transferred to the slag separation device via the slag discharge line. A slag discharge system that can be transported and processed can be provided.

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

It is a schematic block diagram of the coal gasification combined cycle power generation equipment to which the gasification furnace equipment concerning one embodiment of the present invention is applied. It is a schematic block diagram of the gasifier equipment shown in FIG. It is the time-pressure diagram which showed the relationship between the pressure in a gasification furnace at the time of the stop of the gasification furnace equipment which concerns on one Embodiment of this invention, and elapsed time.

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

  An integrated coal gasification combined cycle (IGCC) 10 to which the gasifier facility 14 according to the present embodiment is applied uses air as an oxidant, and the gasifier facility 14 The air combustion system that generates combustible gas (product gas) from the fuel is adopted. And the coal gasification combined cycle power generation facility 10 refines the produced gas generated in the gasification furnace facility 14 into a fuel gas by the gas purification facility 16, and then supplies it to the gas turbine 17 to generate power. That is, the coal gasification combined power generation facility 10 of the present embodiment is an air combustion type (air blowing) power generation facility. As the fuel supplied to the gasifier facility 14, for example, a carbon-containing solid fuel such as coal is used.

  As shown in FIG. 1, a coal gasification combined power generation facility (gasification combined power generation 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. 17, a steam turbine 18, a generator 19, and an exhaust heat recovery boiler (HRSG) 20.

  The coal supply facility 11 is supplied with coal, which is a carbon-containing solid fuel, as raw coal, and pulverizes 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 transfer inert gas supplied from an air separation facility 42 described later at the outlet of the coal supply line 11a, and directed toward the gasifier facility 14. Supplied. The inert gas is an inert gas having an oxygen content of about 5% by volume or less, and representative examples thereof include nitrogen gas, carbon dioxide gas, and argon gas, but are not necessarily limited to about 5% or less.

  The gasifier facility 14 is supplied with pulverized coal produced by the coal supply facility 11 and char (unreacted coal and ash) recovered by the char recovery facility 15 for reuse. Yes.

  In addition, a compressed air supply line 41 from a gas turbine 17 (compressor 61) is connected to the gasifier furnace 14, and a part of the compressed air compressed by the gas turbine 17 is given a predetermined pressure by a booster 68. The gas can be supplied to the gasifier facility 14 after being boosted. The air separation facility 42 separates and generates nitrogen and oxygen from air in the atmosphere, and the air separation facility 42 and the gasifier facility 14 are connected by a first nitrogen supply line 43. The first nitrogen supply line 43 is connected to a coal supply line 11 a from the coal supply facility 11.

  In addition, a second nitrogen supply line 45 branched from the first nitrogen supply line 43 is also connected to the gasification furnace facility 14, and a 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 facility 42 is connected to the compressed air supply line 41 by an oxygen supply line 47. The nitrogen separated by the air separation facility 42 is used as a coal or char transport gas by flowing through the first nitrogen supply line 43 and the second nitrogen supply line 45. 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 furnace 14 includes, for example, a two-stage spouted bed gasifier 101 (see FIG. 2). The gasification furnace facility 14 is gasified by partially burning coal (pulverized coal) and char supplied therein with an oxidant (air, oxygen) to produce a product gas. The gasifier equipment 14 is provided with a foreign substance removal equipment 48 for removing foreign substances (molten slag (hereinafter also simply referred to as slag)) mixed in the pulverized coal. The gasification furnace facility 14 is connected to a gas generation line 49 for supplying a generated gas toward the char recovery facility 15 so that the generated gas containing char can be discharged. In this case, as shown in FIG. 2, a syngas cooler 102 (gas cooler) may be provided in the gas generation line 49 to cool the generated gas to a predetermined temperature before supplying it to the char recovery facility 15.

  The char collection facility 15 includes a dust collection facility 51 and a supply hopper 52. In this case, the dust collection facility 51 is configured by one or a plurality of cyclones or porous filters, and can separate char contained in the product gas generated by the gasification furnace facility 14. The product gas from which the char has been separated is sent to the gas purification facility 16 through the gas discharge line 53. The supply hopper 52 stores the char separated from the generated gas by the dust collection equipment 51. A bin may be disposed between the dust collection facility 51 and the supply hopper 52, and a plurality of supply hoppers 52 may be connected to the bin. A char return line 46 from the supply hopper 52 is connected to the second nitrogen supply line 45.

The gas purification facility 16 performs gas purification by removing impurities such as sulfur compounds and nitrogen compounds from the product gas from which the char has been separated by the char recovery facility 15. The gas purification facility 16 then refines the produced gas to produce fuel gas, and supplies this to the gas turbine 17. Since the product gas from which the char has been separated still contains sulfur (H ₂ S, etc.), the gas purification facility 16 removes and recovers the sulfur with an amine absorption liquid and effectively uses it. To 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 purification facility 16 is connected to the combustor 62, and a combustion gas supply line 67 extending toward the turbine 63 is connected. Is connected. In addition, the gas turbine 17 is provided with a compressed air supply line 41 extending from the compressor 61 to the gasifier facility 14, and a booster 68 is provided in the middle. Accordingly, the combustor 62 generates combustion gas by mixing and combusting 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. The generated combustion gas is supplied to the turbine 63. The turbine 63 rotates the generator 19 by rotating the rotating shaft 64 with the supplied combustion gas.

  The steam turbine 18 includes a turbine 69 that is connected to a rotating shaft 64 of the gas turbine 17, and the generator 19 is connected to a base end portion of the rotating shaft 64. The exhaust heat recovery boiler 20 is connected to an exhaust gas line 70 from the gas turbine 17 (the turbine 63), and heat exchange is performed between the feed water to the exhaust heat recovery boiler 20 and the exhaust gas of the turbine 63, thereby generating steam. Is generated. The exhaust heat recovery boiler 20 is provided with a steam supply line 71 and a steam recovery line 72 between the steam 69 and the turbine 69 of the steam turbine 18, and a condenser 73 is provided in the steam recovery line 72. Further, the steam generated in the exhaust heat recovery boiler 20 may include steam generated by heat exchange with the generated gas in the syngas 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 rotating shaft 64.

A gas purification facility 74 is provided from the outlet of the exhaust heat recovery boiler 20 to the chimney 75.
Here, operation | movement of the coal gasification combined cycle power generation equipment 10 of this embodiment is demonstrated.

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

  In the gasifier furnace 14, the supplied pulverized coal and char are combusted by compressed air (oxygen), and the pulverized coal and char are gasified to generate product gas. The generated gas is discharged from the gasifier facility 14 through the gas generation line 49 and sent to the char recovery facility 15.

  In the char recovery facility 15, the product gas is first supplied to the dust collection facility 51, whereby fine char contained in the product gas is separated. The product gas from which the char has been separated is sent to the gas purification facility 16 through the gas discharge line 53. On the other hand, the fine char separated from the product gas is deposited in the supply hopper 52, returned to the gasifier facility 14 through the char return line 46, and recycled.

  The product gas from which the char has been separated by the char recovery facility 15 is subjected to gas purification by removing impurities such as sulfur compounds and nitrogen compounds in the gas purification facility 16 to produce 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 combusts to generate combustion gas. By rotating the turbine 63 with this combustion gas, the compressor 61 and the generator 19 are driven to rotate through the rotating shaft 64. In this way, the gas turbine 17 can generate power.

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 feed water to the exhaust heat recovery boiler 20, and the generated steam is used as the steam turbine 18. To supply. In the steam turbine 18, the turbine 69 is rotationally driven by the steam supplied from the exhaust heat recovery boiler 20, whereby the generator 19 can be rotationally driven via the rotating shaft 64 to generate electric power.
The gas turbine 17 and the steam turbine 18 do not have to rotate and drive one generator 19 as the same axis, and may rotate and drive a plurality of generators as different axes.

  Thereafter, in the gas purification equipment 74, harmful substances in the exhaust gas discharged from the exhaust heat recovery boiler 20 are removed, and the purified exhaust gas is released 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 facility 14 of this 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.

Hereinafter, each structure with which the gasifier furnace 14 is provided is demonstrated.
Here, in each device shown in FIG. 2, the configuration other than the gasification furnace 101 included in the gasification furnace equipment 14 (foreign matter removal equipment 48, slag discharge line 140, cooling water circulation line 150, circulation pump 160, cooler 170, bypass line 210, first on-off valve 180, second on-off valve 190, control unit 90, etc.) are the slag discharge system of the present embodiment. The gasification furnace facility 14 of this embodiment includes a gasification furnace 101 and a slag discharge system.

  The gasification furnace 101 is formed to extend in the vertical direction (the 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, and partial combustion ( The product gas that has been gasified by pyrolysis is flowing from the lower side in the vertical direction toward the upper side. The gasification furnace 101 includes a pressure vessel 110 and a gasification furnace wall (furnace wall) 111 provided inside the pressure vessel 110. In the gasification furnace 101, an annulus portion 115 is formed in a space between the pressure vessel 110 and the gasification furnace wall 111. Further, the gasification furnace 101 has a combustor unit 116, a diffuser unit 117, and a reductor unit 118 in order from the lower side in the vertical direction (that is, the upstream side in the flow direction of the product gas) in the space inside the gasification furnace wall 111. Is forming.

  The pressure vessel 110 is formed in a cylindrical shape having a hollow space inside, a gas discharge port 121 is formed at the upper end portion, and a slag hopper 122 is formed at the lower end portion (bottom portion). The gasification furnace wall 111 is formed in a cylindrical shape whose inside is a hollow space, and the wall surface thereof is provided to face the inner surface of the pressure vessel 110. In this embodiment, the pressure vessel 110 has 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 in the diffuser part 117 between the combustor part 116 and the reductor part 118. The gasification furnace wall 111 has an upper end in the vertical direction connected to the gas discharge port 121 of the pressure vessel 110 and a lower end in the vertical direction provided with a gap from the bottom of the pressure vessel 110. Cooling water (water storage) is stored in the slag hopper 122 formed below the pressure vessel 110, and the cooling water flows into the lower end portion of 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 the syngas cooler 102 is disposed in the internal space of the gasification furnace wall 111.

  The annulus portion 115 is a space formed inside the pressure vessel 110 and outside the gasification furnace wall 111. In this embodiment, nitrogen, which is an inert gas separated by the air separation equipment 42, is supplied to a nitrogen supply line ( (Not shown). For this reason, the annulus portion 115 becomes a space filled with nitrogen. An in-furnace pressure equalizing pipe (not shown) for equalizing the pressure in the gasification furnace 101 is provided near the upper part of the annulus portion 115 in the vertical direction. The pressure equalizing pipe in the furnace is provided so as to communicate with the inside and outside of the gasification furnace wall 111, and the pressure between the inside (combustor part 116, diffuser part 117 and reductor part 118) and outside (annulus part 115) of the gasification furnace wall 111. The pressure is almost equalized so that the difference is within a predetermined pressure.

  The pressure sensor 128 is a sensor that detects the pressure inside the gasification furnace 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 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via 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 unit 116 is a space for partially burning pulverized coal, char and air, and a combustion apparatus including a plurality of burners 126 is disposed on the gasification furnace wall 111 in the combustor unit 116. The high-temperature combustion gas obtained by burning part of the pulverized coal and char in the combustor unit 116 passes through the diffuser unit 117 and flows into the reductor unit 118.

  The reductor unit 118 is maintained at a high temperature necessary for the gasification reaction, and supplies the pulverized coal to the combustion gas from the combustor unit 116 to partially burn the pulverized coal (for example, carbon monoxide, hydrogen, lower hydrocarbons, etc.). ) To generate gasified product gas. A combustion apparatus including a plurality of burners 127 is arranged on the gasification furnace wall 111 in the reductor unit 118.

  The slag hopper 122 is provided on the vertically lower side of the gasification furnace 101, and receives slag (molten slag) generated in high-temperature gas by combustion of pulverized coal and char, and stores cooling water for cooling the slag. is there. 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 syngas cooler 102 is provided inside the gasification furnace wall 111 and is provided above the burner 127 of the reductor unit 118 in the vertical direction. The syngas cooler 102 is a heat exchanger, and in order from the lower side in the vertical direction of the gasification furnace wall 111 (upstream side in the flow direction of the product gas), an evaporator 131, a superheater (superheater) 132, A charcoal unit (economizer) 134 is arranged. These syngas coolers 102 cool the generated gas by exchanging heat with the generated gas generated in the reductor unit 118. Further, the evaporator (evaporator) 131, the superheater (superheater) 132, and the economizer (economizer) 134 are not limited to the quantities shown in the figure.

Here, the operation of the gasification furnace 101 will be described.
In the gasification furnace 101, nitrogen and pulverized coal are introduced and ignited by the burner 127 of the reductor unit 118, and pulverized coal, char and compressed air (oxygen) are introduced and ignited by the burner 126 of the combustor unit 116. . Then, in the combustor unit 116, high-temperature combustion gas is generated by the combustion of pulverized coal and char. Further, in the combustor section 116, molten slag is generated in the high-temperature gas by the combustion of pulverized coal and char, and this molten slag adheres to the gasification furnace wall 111 and falls to the furnace bottom, and finally in the slag hopper 122. Discharged into the cooling water. Then, the high-temperature combustion gas generated in the combustor unit 116 rises to the reductor unit 118 through the diffuser unit 117. In this reductor unit 118, gasification is performed in which the pulverized coal is mixed with the high-temperature combustion gas and gasified by partial combustion (thermal decomposition) of the pulverized coal in a high-temperature reducing atmosphere while being maintained at a high temperature necessary for the gasification reaction. A reaction takes place and a product gas is produced. The gasified product gas flows from the lower side to the upper side in the vertical direction.

  The foreign matter removal equipment 48 is equipment for removing slag mixed from the mixture of slag discharged from the slag hopper 122 through the slag discharge line 140 and the cooling water, and includes a cyclone (slag separator) 48A, a lock hopper 48B, and storage. A tank 48C, a gate valve 48D, a first discharge valve 48E, and a second discharge valve 48F are provided.

  The cyclone 48A is a device that separates slag from a mixture of slag and cooling water by centrifugal force. 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 to the intake port 48Aa from the slag discharge line 140, which will be described later, and guides the slag vertically downward. The cyclone 48A separates the cooling water from the mixture of slag and cooling water, and discharges the cooling water from the discharge port 48Ab to a 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 gate valve 48D is open. When slag is accumulated in the lock hopper 48B for a predetermined amount or for a predetermined period, the gate valve 48D is closed, and after the pressure reducing operation is performed, the first discharge valve 48E is opened. The slag stored in the lock hopper 48B falls to the storage tank 48C by gravity according 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 open. The slag discharged to the transport vehicle C is transported outside the gasifier facility 14.

The slag discharge line 140 is a pipe that guides the 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 blocking state in which the mixture is blocked.
The slag discharge line 140 is arranged on the upstream side in the flow direction of the mixture with respect to the first on-off valve 180, and on the downstream side in the flow direction of the mixture with respect to the upstream slag discharge line 140A. And a downstream slag discharge line 140B.

  A water intake 141 arranged near the bottom 122A of the slag hopper 122 is provided at the upstream end of the upstream slag discharge line 140A. The slag accumulated in the bottom 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 a water flow generated by a 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 by gravity from the slag hopper 122 and transferred to the cyclone 48 </ b> A, but is transferred by the water flow flowing through the slag discharge line 140. For this reason, the cyclone 48A can be disposed not on the vertically lower side of the gasification furnace 101 but on the side thereof, and the height position of the gasification furnace 101 can be suppressed from becoming high.

  The cooling water circulation line 150 is a pipe that returns the cooling water separated by the cyclone 48 </ b> A and discharged from the discharge port 48 </ b> Ab to the slag hopper 122. The cooling water circulation line 150 includes a circulation pump 160, a cooler 170 that cools the cooling water returned to the slag hopper 122, and a second opening / closing that switches between a circulation state in which the cooling water flows and a blocking state in which the cooling water is blocked. And a valve 190. The cooling water circulation line 150 is disposed upstream of the second opening / closing valve 190 in the circulation direction of the cooling water, and is disposed downstream of the second opening / closing valve 190 in the circulation direction of the cooling water. Downstream cooling water circulation line 150B.

  Circulation pump 160 is a pump that guides a mixture of slag and cooling water from slag hopper 122 to cyclone 48 </ b> A, and forms a water flow that returns cooling water from cyclone 48 </ b> A to slag hopper 122. The circulation pump 160 operates in a state where the slag discharge line 140 and the cooling water circulation line 150 are filled with the mixture or the cooling water, thereby forming the above-described water flow.

The bypass line 210 is a pipe that guides the cooling water stored in the slag hopper 122 to the downstream side cooling water circulation line 150 </ b> B disposed on the downstream side of the second on-off valve 190. A third on-off valve 220 is provided in the bypass line 210.
In the cooling water circulation line 150, the circulation pump 160 according to the present embodiment is disposed on the downstream side in the cooling water circulation direction from the merging 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 arranged on the downstream side in the flow direction of the cooling water from the merging position M, the cooling stored in the slag 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, according to the operation of the circulation pump 160, in the present embodiment, the cooling water can be circulated in the order of the slag 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 facility 14, and includes, for example, a first on-off valve 180, a second on-off valve 190, a third on-off valve 220, a gate valve 48D, a first discharge valve 48E, 2 Controls the open / closed state of the discharge valve 48F. Moreover, the control part 90 controls the discharge amount of the circulation pump 160, for example.

  In FIG. 2, a first position P1 illustrated on the axis X is a vertical height position where the first on-off valve 180 is disposed. A second position P2 illustrated on the axis X is a vertical height position where the second on-off valve 190 is disposed. A third position P3 illustrated 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 indicate the vertical height in the axis X direction with respect to the installation surface S, respectively. As shown in FIG. 2, the vertical position of the third position P3 is higher than the first position P1 and the second position P2.

  The surface of the cooling water stored in the slag hopper 122 is discharged into the vertical upper part of the gasification furnace 101 while the cooling water flows into the lower end of the gasification furnace wall 111 and seals the inside and outside of the gasification furnace wall 111. It is necessary to maintain the system 140 at an appropriate height so that the water retained in the line 140 and the cooling water circulation line 150 does not flow. FIG. 2 shows a state in which the water level 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 retained water flows in due to the pressure due to the water head difference between the first position P1, the second position P2, and the third position P3.

The portion of the slag discharge system 14 that is installed at a height position that is vertically lower than the position P0 of the cooling water surface of the slag hopper 122 is the low head system L, and the height position that is vertically higher than 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 equal to or higher than the pressure due to the head difference between the first position P1, the second position P2, and the third position P3 is required.

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

Next, the stop method of the gasifier furnace (slag discharge system) 14 of this embodiment is demonstrated using FIG.
Immediately after the gasification furnace facility 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. The operating pressure Pr is equal to or higher than a pressure due to a water head difference between the first position P1 and the second position P2 and the third position P3 (hereinafter simply referred to as “water head pressure Ph”). Therefore, the cooling water circulates through the low head system L and the high head system H.

  In the process of stopping the gasifier 14, the pressure in the pressure vessel 110 is reduced from the operating pressure Pr so as to reach a predetermined pressure (for example, normal pressure in this embodiment) lower than the head differential pressure Ph. The decompression is performed by stopping the gas supplied to the gasification furnace 101 such as the coal supply facility 11 and the oxygen supply line 47, and generating in the pressure vessel 110 from a discharge valve (not shown) connected to the gasification furnace 101. This is performed by discharging the gas to the gas generation line 49. The air discharge valve is electrically connected to the control unit 90, and the opening degree is controlled by the control unit 90. The operator may adjust the opening degree manually.

When the pressure in the pressure vessel 110 detected by the pressure sensor 128 approaches the head differential pressure Ph, the third opening / closing valve 220 is opened by the control unit 90 while the circulation pump 160 is operated. . Thereafter, the first opening / closing valve 180 and the second opening / closing valve 190 are closed by the control unit 90 (blocking step). Here, when approaching the hydraulic head differential pressure Ph, it means when reaching a pressure (pressure higher than the hydraulic head differential pressure Ph) with a certain margin with respect to the hydraulic head differential pressure Ph. This is when the pressure reaches about 10% higher than Ph. The pressure range can be changed as appropriate depending on the specifications and operating conditions of the gasifier facility 14.
After the shut-off process, when the pressure is further reduced and the pressure higher than the head differential pressure Ph cannot be maintained (t2), that is, when the high head system H cannot be maintained, the shut-off process causes the first on-off valve 180 and the first Since the 2 on-off valve 190 is closed, the water flow by the circulation pump 160 is formed so as to circulate only through the low head system L. That is, when the gasification furnace 101 is not pressurized to the head differential pressure Ph or higher, the slag 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 water stream is formed.

  After switching from the circulation including the high head system H to the circulation of only the low head system L, swing purge is performed to easily discharge the generated gas including char remaining in the pressure vessel 110 (swing purge process) ). Swing purge is an efficient discharge of product gas including char 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. It is. This also has an effect of preventing the generated gas containing toxic components such as CO gas from remaining in the gasification furnace 101 at the time of periodic inspection when an operator enters the gasification furnace 101. 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 reduced to a normal pressure Po in the present embodiment, for example, as a predetermined pressure lower than the head differential pressure Ph in the stop-time pressure reducing step (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 water 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 increased. The pressurization is performed until a swing purge pressure Pp that is a predetermined value equal to or lower than the water head differential pressure Ph is reached. This swing purge is performed in the range of the normal pressure Po and the water head differential pressure Ph (swing purge pressure Pp), and is executed by repeating the pressure reduction and pressurization cycles at least once. For example, in this 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 outside, and is preferably within about 60 minutes.

  In the present embodiment, after the swing purge is finished (t4), the first on-off valve 180 and the second on-off valve 190 are closed, and the pressure in the gasification furnace 101 is a predetermined pressure smaller than the water head differential pressure Ph. From the state, pressurization is performed so that the pressure in the pressure vessel 110 reaches a predetermined pressure equal to or higher than the water head differential pressure Ph (stop pressurization step). 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), for example, about 10% higher than the head differential pressure Ph. Pressure. The pressure range can be changed as appropriate depending on the specifications and operating conditions of the gasifier facility 14. After the pressure sensor 128 detects that the pressure in the pressure vessel 110 has been increased to a predetermined pressure equal to or higher than the water head differential pressure Ph (t5), the controller 90 controls the first on-off valve 180 and the second on-off valve 190. 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 cooling water circulation in the high head system H is established, the gasification furnace 101 starts to be cooled. 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 as the injected inert gas (inert gas heat-exchanged in the gasification furnace 101) is gasified. It is performed by discharging from the conversion furnace 101. At this time, the pressure in the gasification furnace 101 is kept in a pressurized state (Ph in FIG. 3). The injection and discharge of the inert gas are performed by the above-described injection unit (not shown) and the air discharge valve (not shown), respectively.

According to this embodiment, the following effects can be obtained.
After the gasification furnace facility (slag discharge system) 14 is stopped, the high pressure system H can be circulated by maintaining the pressure in the gasification furnace 101 at or above the head differential pressure Ph. That is, the slag hopper 122 and the cyclone (slag separator) 48A can be connected. As a result, even after the slag discharge system 14 is stopped, residues such as char remaining in the slag hopper 122 can be transported to the slag separation device 48A via the slag discharge line 140 and processed. Therefore, the process of removing the residue in the slag hopper 122 in the periodic inspection performed after the gasifier facility 14 is stopped is shortened.
Further, in the above-described case, after the slag discharge system 14 is stopped, the pressure in the gasification furnace 101 is increased to the water head differential pressure Ph or higher. In introducing the gas used for pressurization of the gasification furnace 101 (inert gas such as nitrogen) into the gasification furnace 101, for example, the gas used for pressurization (inert gas such as nitrogen) is used as the gasification furnace 101. As a result, the weight flow rate of the inert gas serving as the cooling gas can be increased as compared with the case where the gasification furnace 101 is not pressurized. Accordingly, the amount of heat that can be absorbed from the gasification furnace 101 by the inert gas serving as the cooling gas increases, so that the cooling performance by the inert gas serving as the cooling gas is improved.
Further, by performing 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 that remains in the gasification furnace 101 due to the reduced pressure in the gasification furnace 101 is also obtained. Or the like can be dropped onto the slag hopper 122. After swing purge, since the low head system L and the high head system H are connected, the residue dropped on the slag hopper 122 can be transported to the slag separator 48A, and the residue can be processed.

  In the embodiment described above, coal is used as the fuel. However, the present invention can be applied to other carbon-containing solid fuels such as high-grade coal and low-grade coal, and is not limited to coal. Biomass may be used as an organic resource derived from, for example, thinned wood, waste wood, driftwood, grass, waste, sludge, tires, and recycled fuel (pellets and chips) made from these raw materials. It is also possible to use it.

  Moreover, although this embodiment demonstrated the tower type gasification furnace as the gasification furnace 101, the gasification furnace 101 produces | generates the vertical up-down direction of each apparatus in the gasification furnace 101 also with a crossover type gasification furnace. It can be implemented in the same way by replacing the gas flow direction to match.

10 Coal gasification combined power generation facility (gasification combined power generation facility)
14 Gasifier equipment (slag discharge system)
19 Generator 48 Foreign object removal equipment 48A Cyclone (slag separator)
48Aa intake 48Ab discharge 48B lock hopper 48C storage tank 48D gate valve 48E first discharge valve 48F second discharge valve 49 gas generation line 90 control unit 101 gasification furnace 102 syngas cooler 110 pressure vessel 111 gasification furnace wall (furnace wall)
115 Annulus part 116 Combustor part 117 Diffuser part 118 Reductor part 121 Gas discharge port 122 Slag hopper 122A Bottom part 126, 127 Burner 128 Pressure sensor (pressure detection part)
131 Evaporator
132 Superheater (super heater)
134 economizer
140 Slag Discharge Line 140A Upstream Slag Discharge Line 140B Downstream Slag Discharge Line 141 Intake 150 Cooling Water Circulation Line 150A Upstream Cooling Water Circulation Line 150B Downstream Cooling Water Circulation Line 160 Circulation Pump 170 Cooler 180 First Open / Close Valve 190 Second Opening / Closing Valve 210 Bypass line 220 Third on-off valve C Transport vehicle S Installation surface X Axis

Claims (6)

A slag hopper provided in a vertically lower side of a gasification furnace that gasifies the carbon-containing solid fuel, and stored with cooling water for cooling slag falling in the gasification furnace;
A slag separation device for separating the slag from a mixture of the slag and the cooling water;
A first open / close valve, and a slag discharge line for guiding 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;
A circulating pump provided downstream of the second on-off valve in the cooling water circulation line;
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;
A method for stopping a slag discharge system comprising:
The third position in the vertical direction of 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,
The first on-off valve and the second on-off valve are in a closed state, and the gas pressure in the gasification furnace is smaller than the water head differential pressure between the first position, the second position, and the third position. From the state of the pressure, a pressurizing step at the time of pressurizing the pressure in the gasifier to a predetermined pressure larger than the water head differential pressure,
A connecting step of opening the first on-off valve and the second on-off valve after the stopping pressurization step;
Method for stopping slag discharge system.   Prior to the stop-time 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 water head differential pressure. The method for stopping the slag discharge system according to claim 1, comprising a blocking step.   While the cooling water is circulated between the slag hopper and the cooling water circulation line via the bypass line by the blocking step, a predetermined pressure in which the pressure in the gasifier is smaller than the water head differential pressure. 3. The slag discharge according to claim 2, further comprising a swing purge 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 a predetermined range of the gasification furnace. How to stop the system.   The method of stopping the slag discharge system according to claim 3, wherein the pressure reduction in the swing purge step is to reduce the pressure in the gasification furnace to a normal pressure. A slag hopper provided in a vertically lower side of a gasification furnace that gasifies the carbon-containing solid fuel, and stored with cooling water for cooling slag falling in the gasification furnace;
A slag separation device for separating the slag from a mixture of the slag and the cooling water;
A first open / close valve, and a slag discharge line for guiding 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;
A circulating pump provided downstream of the second on-off valve in the cooling water circulation line;
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;
With
The third position in the vertical direction of 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,
The first on-off valve and the second on-off valve are in a closed state, and the gas pressure in the gasification furnace is smaller than the water head differential pressure between the first position, the second position, and the third position. A controller that pressurizes the pressure in the gasifier to a predetermined pressure greater than the water head differential pressure and then opens the first on-off valve and the second on-off valve. Slag discharge system. A slag discharge system according to claim 5;
A gas turbine that is rotationally driven by burning at least part of the product gas generated in the gasification furnace;
A steam turbine that is rotationally driven by steam generated by an exhaust heat recovery boiler that introduces turbine exhaust gas discharged from the gas turbine;
A generator connected to a rotating shaft of the gas turbine and / or the steam turbine;
A gasification combined power generation device comprising:

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