JP2013227397A - Gasification system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the reduction of efficiency in a system, and to prevent the damage of a furnace wall in a gasification furnace and the clogging of a passage.SOLUTION: A gasification system is equipped with a gasification furnace 11, a char-transporting apparatus 28, a shift reactor 23 installed in the subsequent stage side, a carbon dioxide feeder 27, and a first steam-feeding pipe 35 for feeding steam to a gasification chamber 14. The gasification furnace 11 has the gasification chamber 14 equipped with burners for feeding a carbon-based solid raw material and an oxidant, installed in upper and lower stages, a narrowed part 15, and a heat-recovering part 16. The char-transporting apparatus 28 transports the char collected by a char-collecting device 21 installed in the subsequent stage side of the gasification furnace 11 to the gasification chamber 14. The carbon dioxide feeder 27 feeds a part of the carbon dioxide separated by a carbon dioxide-separating and collecting apparatus 24 installed in the subsequent stage side of the shift reactor 23, as a gas for transporting the carbon-based solid raw material and the char. The first steam-feeding pipe 35 has a first feeding amount controller 40 for controlling the feeding amount of the steam according to the amount of the char discharged from the gasification chamber 14 and the gas temperature in the gasification chamber 14.

Description

  The present invention relates to a gasification system, and more particularly to a gasification system including a gasification furnace that gasifies a carbon-based solid material to generate a combustible gas.

  For example, finely pulverized coal is supplied to a high-temperature gasifier together with an oxidant to generate a combustible gas mainly composed of carbon monoxide and hydrogen, while ash generated with the combustible gas is free from harmful components. An air-bed coal gasification method that converts to slag and recovers is known. This type of gasification system has excellent characteristics such as high plant efficiency, excellent environmental conservation, and many applicable raw material types. For example, coal gasification combined power generation system and coal gasification fuel Application to a next-generation thermal power generation system such as a combined battery power generation system, or a hydrogen production system for coal liquefaction or chemical raw materials is being studied.

  On the other hand, as a measure against global warming, the release of carbon dioxide into the atmosphere is suppressed by compressing the combustible gas discharged from the gasifier and recovering the carbon dioxide separated from the combustible gas. Technology is drawing attention.

  In FIG. 2, the prior art example of the gasification system which applied the airflow bed coal gasification method is shown. The gasification furnace 11 has a gasification chamber 14 to which pulverized coal and an oxidant are supplied from upper and lower two-stage burners 12 and 13, and a flow passage cross-sectional area above (downstream side) of the gasification chamber 14 to reduce gas. A throttle 15 for discharging the combustible gas generated in the gasification chamber, a heat recovery unit 16 for cooling the combustible gas that has passed through the throttle 15, and a furnace bottom for storing quench water 17 below the gasification chamber 14 18.

  In the gasification chamber 14 of the gasification furnace 11, the pulverized coal stored in the raw material supply hopper 19 is air-conveyed by nitrogen or the like and supplied from the upper burner 13 and the lower burner 14, and the oxidant is added to the upper burner 13 and Supplied from the lower burner 14. In the gasification chamber 14, the pulverized coal and the oxidant react to generate a combustible gas mainly composed of carbon monoxide and hydrogen. Generally, since the supply amount of the oxidant supplied from the lower burner 14 is set to be larger than the supply amount of the oxidant supplied from the upper burner 13, the lower stage side of the gasification chamber 14 contains ash generated together with combustible gas. Heated above the melting temperature. For this reason, the ash heated on the lower stage side becomes molten slag, which flows down to the quench water 17 at the furnace bottom 18 and is cooled and solidified.

  The combustible gas generated in the gasification chamber 14 is introduced into the heat recovery unit 16 through the throttle unit 15 and cooled, and then discharged from the gasification furnace 11 and introduced into the heat recovery boiler 20. The temperature is decreased to 200 to 400 ° C. The combustible gas reduced in temperature by the heat recovery boiler 20 is introduced into the char recovery device 21, and the char containing unburned carbon accompanying the combustible gas is separated. The combustible gas from which the char has been separated is introduced into the gas purifier 22, and after the sulfur and halogen components of the combustible gas are removed, the combustible gas is introduced into the shift reaction device 23. Water vapor is introduced into the shift reaction device 23, and this water vapor reacts with carbon monoxide in the combustible gas to generate hydrogen and carbon dioxide. The combustible gas mainly composed of hydrogen and carbon dioxide is introduced into the carbon dioxide separation and recovery device 24 and compressed by a compressor (not shown) to separate the carbon dioxide. The combustible gas in which carbon dioxide is separated and hydrogen is the main component is used as a fuel for a gas turbine or the like.

  On the other hand, in order to prevent char from adhering to the wall surface of the throttle part 15 and closing the flow path when the combustible gas passes through the throttle part 15, the combustible gas has a lower temperature than the combustible gas passing through the throttle part 15. The gas is extracted from the downstream side of the gas purifier 22 and introduced as a coolant in the vicinity of the throttle unit 15. Further, the char recovered by the char recovery device 21 is stored in the char supply hopper 25 and is then entrained by nitrogen gas or the like, and is conveyed to the gasification furnace 11 by airflow, and is substantially the same as the lower burner 12 of the gasification chamber 14. It introduce | transduces in a furnace from the nozzle 26 installed in height.

  By the way, when the carbon dioxide separation and recovery device 24 is provided as in the gasification system of FIG. 2, a large amount of power is required to drive the compressor, leading to a reduction in efficiency of the gasification system. In particular, since the steam is excessively supplied to the shift reaction device 23 with respect to the carbon content contained in the pulverized coal, and energy for that amount is consumed, for example, coal gasification combining a gas turbine and a steam turbine. In the combined system (IGCC), the plant efficiency is reduced by about 20 to 30% compared to the case where the carbon dioxide separation and recovery device 24 is not provided.

  In contrast, a part of the carbon dioxide separated from the combustible gas is introduced into the gasification furnace, and this carbon dioxide is reacted with the unburned carbon content of char to gasify, that is, carbon dioxide and carbon monoxide. A technique is known in which by generating carbon, the carbon conversion rate of the raw material in the gasification furnace is increased and the efficiency reduction of the gasification system is suppressed.

  In Patent Document 1, in a gasification system including a gasification furnace that generates a combustible gas by reacting a pulverized coal raw material and an oxidant, carbon dioxide is separated from the combustible gas discharged from the gasification furnace, A technique is disclosed in which the separated carbon dioxide is used as a conveying gas for the pulverized coal raw material and carbon dioxide is supplied as a cooling gas near the outlet of the gasification furnace.

  According to this, since the carbon dioxide introduced into the gasification furnace has an endothermic reaction with the carbon content of the pulverized coal raw material, the gasification efficiency of the pulverized coal raw material is increased without increasing the furnace temperature of the gasification furnace. Can do. Moreover, since the temperature rise near the exit of the gasification furnace is suppressed by introducing carbon dioxide, it is possible to suppress the adhesion of ash to the furnace wall.

JP 2008-291081 A

  However, when the technique using carbon dioxide as in Patent Document 1 is applied to the gasification furnace having the two-stage burner of FIG. 2, the following problems may occur.

  First, as carbon dioxide is introduced into the gasification furnace as the first problem, the char gasification reaction is promoted, so the amount of char discharged from the gasification furnace decreases, and accordingly The amount of char introduced into the furnace via the lower side of the gasification chamber, that is, the nozzle 26, is reduced. Thereby, the supply amount of the oxidant supplied from the lower side of the gasification chamber, that is, the lower burner 12, is reduced. However, the upper side of the gasification chamber, that is, the upper burner 13 is reduced with the reduction of the supply amount of the oxidant. Since the amount of the oxidant supplied from the gas generator is increased, the temperature on the upper side of the gasification chamber rises and the upper side furnace wall may be damaged.

  As a second problem, in the case of using raw coal with low gasification reaction reactivity, the amount of carbon dioxide supplied to the gasifier is reduced in order to reduce the amount of char generated by the gasification reaction. As a result, the power required to separate carbon dioxide from the combustible gas in the carbon dioxide separation and recovery apparatus increases, which may cause a reduction in efficiency of the gasification system.

  Furthermore, as a third problem, when carbon dioxide is introduced into the gasification furnace and the gasification reaction of char is promoted, the unburned carbon content of char is gasified and the ash ratio increases remarkably. If the char adheres to the furnace wall of the throttle part of the gasification furnace, it immediately causes sintering, which may cause clogging of the flow path. For this reason, when carbon dioxide is introduced into the furnace as the cooling gas for the throttle part, the carbon content of the combustible gas increases, and as a result, the power of the carbon dioxide separation and recovery device increases and the efficiency of the gasification system decreases. May be incurred.

  The present invention has been made in view of these problems, and suppresses a reduction in system efficiency in a gasification system having equipment for recirculating char and carbon dioxide separated from combustible gas to a gasification furnace. Another object is to prevent damage to the furnace wall in the gasification furnace and blockage of the flow path.

  In a gasification system that supplies carbon dioxide from the outside to the inside of a gasification furnace that generates a combustible gas by reacting a carbon-based solid material and an oxidant, the more carbon dioxide that is supplied to the gasification furnace, The gasification reaction is promoted, the carbon content of the combustible gas generated from the gasification furnace is increased, and the power for separating carbon dioxide from the combustible gas is increased. Therefore, in the present invention, water vapor is used in addition to carbon dioxide as a gasifying agent for gasifying the carbon content of the carbon-based solid material. Since this water vapor reacts with carbon to generate carbon monoxide and hydrogen, it can suppress an increase in the carbon content of combustible gas as compared with carbon dioxide that reacts with carbon and generates only carbon monoxide. .

  Specifically, in order to solve the above problems, the present invention provides a gasification chamber in which burners for supplying a carbon-based solid raw material and an oxidizer are installed in upper and lower stages to generate a combustible gas, and a downstream side of the gasification chamber A gasification furnace having a throttle part for reducing the cross-sectional area of the flow path and discharging combustible gas from the gasification chamber, and a heat recovery part for cooling the combustible gas downstream of the throttle part, and from this gasification furnace The char recovery device that recovers the char accompanying the discharged combustible gas, the char transfer device that transfers the char recovered by the char recovery device to the gasification chamber of the gasification furnace, and the char recovery device. A shift reactor that generates hydrogen and carbon dioxide by supplying water vapor to the combustible gas, a carbon dioxide separation and recovery device that separates and recovers carbon dioxide from the combustible gas that has passed through the shift reactor, and carbon dioxide separation and recovery Times with equipment In a gasification system having a carbon dioxide supply device for supplying a part of the carbon dioxide as a carrier gas for carbon-based solid material and supplying a carrier gas for char, water vapor is supplied to the gasification chamber of the gasifier The first water vapor supply pipe is provided, and the first water vapor supply pipe adjusts the water supply amount according to the discharge amount of the char discharged from the gasification chamber and the gas temperature of the gasification chamber. 1 supply amount adjusting device.

  That is, even if water vapor is introduced into the gasifier instead of carbon dioxide, the carbon-based solid material can be gasified and the amount of char generated can be reduced, so that a predetermined amount of water vapor is introduced into the gasifier. Thus, the carbon dioxide introduced into the gasification furnace can be reduced to a necessary amount as a carrier gas. Therefore, according to the present invention, the carbon content of the combustible gas discharged from the gasification furnace can be reduced, so that the power of the carbon dioxide separation and recovery device can be reduced and the efficiency of the gasification system can be improved. realizable.

  By the way, when the discharge amount of char discharged from the gasification furnace is reduced by the gasification reaction of the steam supplied to the gasification furnace, the amount of char introduced to the lower side of the gasification chamber is reduced accordingly. . Then, the supply amount of the oxidant supplied from the lower burner is reduced and the supply amount of the oxidant supplied from the upper burner is increased, so that the furnace temperature on the upper stage side may increase. In the present invention, even in such a case, the supply amount of water vapor can be adjusted according to the increase in the gas temperature of the gasification chamber, so that the inside of the furnace can be maintained in an appropriate temperature range, The furnace wall can be prevented from thermal damage. In addition, even when the unburned carbon content of the char is gasified and the ash ratio is significantly increased, for example, by increasing the temperature of the gas flowing through the throttle by supplying water vapor to the gasification chamber near the throttle Therefore, even if the char adheres to the furnace wall of the throttle part, sintering does not occur immediately, and the blockage of the gas flow path can be prevented.

  On the other hand, in the case of using a carbon-based solid raw material having low gasification reaction reactivity, the generation of char may not be sufficiently suppressed with the supply amount of water vapor adjusted according to the temperature of the gasification chamber. . In this regard, in the present invention, the supply amount of water vapor is adjusted not only according to the temperature of the gasification furnace but also according to the discharge amount of the char discharged from the gasification furnace. Can be stably suppressed.

  Thus, according to the present invention, the amount of water vapor supplied to the gasification furnace can be adjusted using both the temperature of the gasification furnace and the discharge amount of char discharged from the gasification furnace. It is possible to achieve both prevention of wall damage and channel blockage and suppression of system efficiency reduction.

  The steam supplied to the gasifier in the present invention is, for example, steam generated in a heat recovery boiler installed in the heat recovery section of the gasification furnace or in the subsequent stage of the gasification furnace, or in an exhaust heat recovery boiler in the combined power generation system. May be used, and may be distributed from a supply system of water vapor supplied to the shift reactor, or may be supplied from another supply system.

  In this case, a second water vapor supply pipe for supplying water vapor to the throttle unit is provided, and the second water vapor supply pipe adjusts the supply amount of water vapor in accordance with the gas temperature in the vicinity of the throttle unit or the throttle unit. 2 supply amount adjusting devices.

  Thus, by directly supplying water vapor to or in the vicinity of the throttle portion, it is possible to effectively suppress the temperature rise of the throttle portion and more reliably prevent the blockage of the throttle portion from being blocked. In addition, since the water vapor supplied to or near the throttle portion reacts with carbon monoxide generated in the gasification chamber and is converted into carbon dioxide and hydrogen, the carbon monoxide content of the combustible gas does not increase. . For this reason, since the quantity of the water vapor | steam supplied to a subsequent shift reaction apparatus can be reduced, and also the motive power of a carbon dioxide separation and recovery apparatus can be reduced, the efficiency fall of a system can be suppressed more effectively.

  Here, the first and second supply amount adjusting devices adjust so that the sum of the supply amount of water vapor supplied to the gasification chamber and the throttle unit and the supply amount of water vapor supplied to the shift reaction device becomes the set flow rate. Shall be made.

  The total amount of water vapor supplied to the gasification system of the present invention, that is, the set flow rate can be set based on, for example, the carbon content of the carbon-based solid fuel supplied to the gasification furnace. For example, in the case of a configuration in which water vapor is supplied only to the shift reactor, the amount of water vapor supplied to the shift reactor becomes the set flow rate, but even if a part of the set flow rate is distributed to the gasification chamber and the throttle unit, the system Since the total amount of water vapor supplied to the water does not change, the efficiency of the system associated with the production of water vapor is not reduced.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing the efficiency fall of a system, the damage of the furnace wall in a gasification furnace and the obstruction | occlusion of a flow path can be prevented.

1 is a system diagram of a gasification system to which the present invention is applied. It is a systematic diagram of the conventional gasification system.

  Hereinafter, an embodiment of a gasification system to which the present invention is applied will be described in detail with reference to FIG. In this embodiment, an example in which pulverized coal obtained by pulverizing coal is used as a carbon-based solid raw material supplied to a gasification furnace will be described, but the present invention is not limited to this example, and other solid fuels such as biomass Can be used after being crushed. In the present embodiment, the same components as those in FIG. 2 are denoted by the same reference numerals, description thereof is omitted, and differences from FIG. 2 will be mainly described.

  The gasification system of this embodiment includes a gasification furnace 11, a heat recovery boiler 20, a char recovery device 21, a gas purification device 22, a shift reaction device 23, a carbon dioxide separation and recovery device 24, a carbon dioxide supply device 27, and a char transport device. 28.

  The carbon dioxide supply device 27 is a device that supplies a part of the carbon dioxide separated and recovered by the carbon dioxide separation and recovery device 24 as pulverized coal and char transport gas. Carbon dioxide is used as the char transport gas. A first carbon dioxide supply line 29 to be supplied, a second carbon dioxide supply line 30 to supply carbon dioxide as a conveying gas for pulverized coal, and a compressor 31 are provided.

  One end of the first carbon dioxide supply pipe 29 is connected in the middle of the discharge pipe 32 through which the carbon dioxide discharged from the carbon dioxide separation and recovery device 24 flows, and the char that conveys the char stored in the char supply hopper 25. The other end is connected to the upstream side of the conveyance conduit 33, and the compressor 31 is disposed between the both ends. The second carbon dioxide supply line 30 has one end connected to the downstream side of the compressor 31 in the first carbon dioxide supply line 29, and pulverized coal conveying the char stored in the two raw material supply hoppers 19. The other end is connected to the upstream side of the conveyance pipeline 34.

  The char transport device 28 includes a char supply hopper 25 and a char transport pipe 33. One end of the char transport pipe 33 is connected to the bottom of the char supply hopper 25, and the other end is connected to the nozzle 26. The char supply hopper 25 is configured such that the char discharged from the bottom of the char recovery device 21 is supplied from the top, while when a predetermined amount of char is stored, the char outlet is opened by opening the discharge port at the bottom. . The char supplied to the char transport pipe 33 is accompanied by carbon dioxide introduced into the char transport pipe 33 and has a height approximately equal to that of the lower burner 12 on the lower side of the gasification chamber 14 from the nozzle 26. Introduced in position.

  Further, the gasification system of the present embodiment includes a first water vapor supply pipe 35 and a second water vapor supply pipe 36 that supply water vapor to a gasification furnace 11 from a water vapor supply source (not shown). One end of the first steam supply pipe 35 is connected to the upper side of the gasification chamber 14 of the gasification furnace 11, that is, a nozzle 37 disposed at substantially the same height as the upper burner 13, and a shift reaction is performed from the steam supply source. The other end is connected to the middle of a third water vapor supply pipe 38 for supplying water vapor to the device 23. One end of the second water vapor supply pipe 36 is connected to a nozzle 39 installed toward the throttle unit 15 of the gasification furnace 11, and the other end is connected to the middle of the third water vapor supply pipe 38.

  The first water vapor supply pipe 35 is provided with a first supply amount adjusting device 40 that adjusts the flow rate of water vapor according to the opening of the valve. The first supply amount adjustment device 40 includes a weight detection device 41 that is provided in the char transport pipe 33 and detects the weight of the char supplied to the gasification furnace 11, and the gasification chamber 14 of the gasification furnace 11. The first temperature detection unit 42 that directly detects the temperature of the gas flowing through the upper stage is electrically connected to each other, and the results detected by the weight detection device 41 and the first temperature detection unit 42 are converted into electric signals, respectively. The opening of the valve is adjusted according to the input result. The weight detection device 41 can adopt a well-known configuration, and is based on the discharge amount of the char discharged from the char supply hopper 25 at a time and the flow rate of the transport gas flowing through the char transport conduit 33 per unit time. The passing weight of the char may be obtained, or the weight of the chars to be collectively discharged after temporarily storing the char may be measured. The first temperature detection unit 42 is configured to directly detect the gas temperature by inserting a temperature detection terminal into the furnace of the gasification furnace 11.

  The second water vapor supply pipe 36 is provided with a second supply amount adjusting device 43 that adjusts the flow rate of the water vapor according to the opening of the valve. The second supply amount adjusting device 43 is electrically connected to a second temperature detection unit 44 that directly detects the temperature of the gas flowing in the vicinity of the throttle unit 15 of the gasification furnace 11, and the second temperature detection unit 44. The detection result is converted into an electrical signal and input, and the opening of the valve is adjusted according to the input result. The second temperature detection unit 44 has the same configuration as the first temperature detection unit 42.

  The carbon dioxide separated from the combustible gas by the carbon dioxide separation / recovery device 24 is discharged through the discharge pipe 32 and led to the first carbon dioxide supply pipe 29. The carbon dioxide led to the first carbon dioxide supply pipe 29 is compressed by the compressor 31 and then led to the char transport pipe 33. On the other hand, part of the carbon dioxide compressed by the compressor 31 is guided to the second carbon dioxide supply conduit 30 and introduced into the two pulverized coal conveying conduits 34. The carbon dioxide introduced into the char transfer conduit 33 is introduced into the gasification chamber 14 from the nozzle 26 along with the char discharged from the char supply hopper 25. The carbon dioxide introduced into the pulverized coal conveyance pipe 34 is accompanied by the pulverized coal discharged from the raw material supply hopper 19 and is introduced into the gasification chamber 14 of the gasifier 11 from the lower burner 12 and the upper burner 13. . Note that oxygen is introduced from the lower burner 12 and the upper burner 13 through a flow path different from that for carbon dioxide.

In the gasification chamber 14 of the gasification furnace 11, pulverized coal and oxygen react to generate carbon dioxide, and the char gasification reaction shown in the formula (1) proceeds by the carbon dioxide to generate combustible gas. The In the present embodiment, carbon dioxide is used as the transport gas for pulverized coal and char, and in addition to the carbon dioxide generated in the gasification chamber 14, the carbon dioxide as the transport gas is gasified in the gasification chamber 14. Since it contributes to the reaction, the gasification reaction of the unburned carbon content of char is promoted.
C + CO ₂ → 2CO (1)

  Although the combustible gas discharged from the gasification furnace 11 is accompanied by char, the generation of char is suppressed by the effect of promoting the gasification reaction by carbon dioxide. There is almost no remaining and the ash content of char is high. For this reason, the amount of char supplied to the lower side of the gasification chamber 14 through the nozzle 26 is small, and as a result, the total amount of oxygen supplied to the gasification chamber 14 is supplied from the lower burner 12 and the upper burner 13. The distribution of oxygen amount is higher in the upper burner 13. When the distribution of the amount of oxygen supplied from the upper burner 13 becomes higher, the jet flame of the upper burner 13 becomes larger, the temperature on the upper stage side of the gasification chamber 14 rises, and the furnace wall may be damaged.

  In this respect, in this embodiment, since water vapor is supplied toward the gasification chamber 14 of the gasification furnace 11, an increase in the furnace temperature can be suppressed and thermal damage to the furnace wall can be prevented. . In particular, in the present embodiment, the temperature of the gas flowing in the upper stage side of the gasification chamber 14 is detected by the first temperature detection unit 42, and the first supply amount adjusting device 40 is controlled according to the detection result. Therefore, for example, when the temperature detected by the first temperature detection unit 42 rises, the supply amount of water vapor supplied from the nozzle 37 can be increased to a predetermined amount. Thereby, since an appropriate amount of water vapor can be supplied according to the temperature change of the gasification chamber 14, the temperature of the gasification chamber 14 can be maintained within a predetermined range.

  By the way, when pulverized coal of a carbon-based solid raw material having low reactivity of gasification reaction is used, it is supplied according to the carbon dioxide supplied to the gasification furnace 11 as the transfer gas and the temperature of the gasification chamber 14. In some cases, water vapor alone cannot sufficiently gasify the unburned carbon contained in the combustible gas. In this case, the unburned carbon content is discharged as char from the gasification furnace 11, recovered by the char recovery device 21, and finally returned to the gasification chamber 14.

  In this regard, in this embodiment, in addition to the detected temperature of the gasification chamber 14, the weight of the char supplied to the gasification chamber 14 is detected by the weight detection device 41, and the first supply amount is determined according to the detection result. The adjusting device 40 is controlled. For this reason, for example, when the discharge amount of the char discharged from the gasification furnace 11 increases and the weight detected by the weight detection device 41 increases, by increasing the supply amount of the steam supplied from the nozzle 37, The gasification reaction of unburned carbon can be promoted.

  Here, the weight detected by the weight detection device 41 is the weight of the char flowing along the char transport pipe 33 along with the carbon dioxide, and this weight is the char discharged from the gasification furnace 11. Therefore, it can be a means for indirectly detecting the discharge amount of char. Instead of the means for indirectly detecting the discharge amount of char discharged from the gasification furnace 11 in this way, a known configuration for directly detecting the discharge amount of char may be adopted.

The water vapor supplied to the gasification chamber 14 acts as a gasifying agent in the same manner as carbon dioxide, and the char gasification reaction shown in the formula (2) proceeds to generate flammable gas, so that it is scattered. Char has almost no unburned carbon. Accordingly, by supplying a predetermined amount of water vapor according to the temperature of the gasification chamber 14 and the amount of char discharged from the gasification chamber 14 to the gasification chamber 14, the gasification reactivity of pulverized coal is affected. Therefore, the gasification furnace 11 can be operated with high gasification efficiency and excellent safety.
C + H ₂ O → CO + H ₂ (2)

  As in this embodiment, by supplying an appropriate amount of water vapor to the gasification chamber 14 of the gasification furnace 11, gasification of pulverized coal can be promoted and the amount of char generated can be reduced. For this reason, according to this embodiment, it is not necessary to supply a large amount of carbon dioxide to the gasification furnace 11 for the purpose of gasifying the unburned carbon content of the char as in the prior art, and the minimum necessary as a carrier gas. The supply amount can be limited to the limit. Further, according to this embodiment, the carbon content of the combustible gas generated in the gasification furnace 11 is not increased, and the power of the carbon dioxide separation and recovery device 24 is not increased. Can be improved.

  By the way, when the char accompanied by the combustible gas generated in the gasification chamber 14 adheres to the furnace wall constituting the throttle unit 15 and the heat recovery unit 16, the ash contained in the char causes sintering and grows. May block the flow path and prevent the gasifier from continuing to operate safely. Further, the degree of sintering of char becomes stronger as the temperature of the atmospheric gas increases and as the ash content of char increases.

  In this respect, in this embodiment, since the ash content of the char accompanying the combustible gas is remarkably high, in order to prevent ash from adhering to the throttle portion 15 and the furnace wall in the vicinity thereof, sintering is performed. Water vapor is supplied toward the section 15 to cool the gas flowing in the throttle section 15 and its vicinity. More specifically, the temperature of the gas flowing in the vicinity of the throttle unit 15 is continuously detected by the second temperature detection unit 44, and the second supply amount adjusting device 43 is controlled according to the detection result. ing. For this reason, for example, when the temperature detected by the second temperature detection unit 44 rises, the supply of water vapor from the nozzle 39 toward the throttle unit 15 is started, or the amount of water vapor supplied to the throttle unit 15 is reduced. Can be increased to an appropriate amount. As a result, the temperature of the gas flowing through the throttle unit 15 can be reduced as necessary, and blockage of the flow path due to ash sintering is prevented, and stable gasification operation is possible.

  Here, the temperature of the throttle portion 15 is preferably adjusted to 1100 ° C. or lower, for example. According to the inventors' analytical examination, for example, when the temperature of the combustible gas flowing in the vicinity of the upper stage of the gasification chamber 14 is about 1300 ° C., the amount of pulverized coal supplied to the gasification furnace 11 is If water vapor in an amount of 60% by weight is supplied, the temperature of the combustible gas can be lowered to 1100 ° C.

  The water vapor supplied from the nozzle 39 to the throttle unit 15 reacts with carbon monoxide in the combustible gas generated in the gasification chamber 14 and is converted into carbon dioxide and hydrogen. The carbon oxide content does not increase. Therefore, it is not necessary to increase the amount of water vapor supplied to the shift reaction device 23, thereby preventing a reduction in system efficiency.

  In the present embodiment, the first water vapor supply pipe 35 and the second water vapor supply pipe 36 are respectively branched from the third water vapor supply pipe 38, and the first water vapor supply pipe 35 includes a first supply amount adjusting device. 40 is provided, and the second water supply pipe 36 is provided with a second supply amount adjusting device 43. The sum of the amount of steam supplied to the gasification furnace 11 and the amount of steam supplied to the shift reactor 23 is always a constant set flow rate, and the steam and gas supplied to the shift reactor 23 within that range. The distribution of the supply amount of the water vapor supplied to the chemical conversion chamber 14 and the water vapor supplied to the throttle unit 15 is adjusted.

  For example, in the configuration of the gasification system of FIG. 2, the amount of water vapor supplied to the shift reactor 23 is set based on the carbon content in the pulverized coal supplied to the gasification furnace 11. The amount is set excessively with respect to the carbon content of the pulverized coal. In this embodiment, when the amount of water vapor supplied to the shift reaction device 23 is a set flow rate, the total amount of water vapor supplied to the entire system is the set flow rate. That is, even if a part of the steam supplied to the shift reactor 23 is supplied to the gasification furnace 11 as in the present embodiment, the total amount of steam supplied to the entire system remains unchanged. The efficiency of the system is not reduced as the supply amount increases.

  As described above, according to the present embodiment, in the gasification system having the facility for recirculating the char and carbon dioxide separated from the combustible gas to the gasification furnace 11, the combustible gas can be efficiently produced from the pulverized coal raw material. In addition, it is possible to prevent damage to the furnace wall in the gasification furnace 11 and blockage of the gas flow path, and to minimize a decrease in efficiency of the gasification system.

  As mentioned above, although embodiment of this invention has been explained in full detail with drawing, the said embodiment is only an illustration of this invention and this invention is not limited only to the structure of the said embodiment. Needless to say, changes in design and the like within the scope of the present invention are included in the present invention.

  For example, in the above embodiment, an example in which the first water vapor supply pipe 35 and the second water vapor supply pipe 36 are branched from the third water vapor supply pipe 38, respectively, is not limited thereto. For example, the first to third water vapor supply pipes may be independent supply paths. In this case, for example, each water vapor supply pipe is provided with a supply amount adjusting device for adjusting the amount of water vapor supplied so that the total amount of water vapor supplied to the entire system can be adjusted to the set flow rate. Is good.

  Moreover, in this embodiment, although the structure which detects directly the gas temperature which flows through the inside of the gasification furnace 11 with the 1st temperature detection part 42 and the 2nd temperature detection part 44 was shown, in addition, the temperature in a furnace is shown. A well-known configuration that indirectly detects from the outside of the furnace can also be adopted. The second temperature detection unit 44 directly detects the gas temperature flowing in the vicinity of the throttle unit 15, but instead of this, the gas temperature flowing in the flow path of the throttle unit 15 is directly detected. Of course.

  Moreover, in this embodiment, although the example which installs the burner provided in the gasification chamber 14 in two steps of upper and lower in the gasification furnace 11 was shown, it is not restricted to this, A burner is installed in multiple steps in the up-down direction. It can also be set as the structure to do.

DESCRIPTION OF SYMBOLS 11 Gasification furnace 12 Lower burner 13 Upper burner 14 Gasification chamber 15 Restriction part 16 Heat recovery part 21 Char recovery apparatus 23 Shift reaction apparatus 24 Carbon dioxide separation recovery apparatus 25 Char supply hopper 26, 37, 39 Nozzle 27 Carbon dioxide supply apparatus 28 Char transport device 29 First carbon dioxide supply line 30 Second carbon dioxide supply line 35 First water vapor supply pipe 36 Second water vapor supply pipe 38 Third water vapor supply pipe 40 First supply amount adjustment Device 41 Weight detection device 42 First temperature detection unit 43 Second supply amount adjustment device 44 Second temperature detection unit

Claims (3)

A burner for supplying a carbon-based solid raw material and an oxidant is installed in the upper and lower stages to reduce the cross-sectional area of the gasification chamber that generates combustible gas and the downstream side of the gasification chamber, and the combustible gas is A gasification furnace having a constriction section that discharges from the gasification chamber and a heat recovery section that cools the combustible gas downstream of the constriction section;
A char recovery device that recovers the char accompanying the combustible gas discharged from the gasification furnace, and a char transfer that transfers the char recovered by the char recovery device to the gasification chamber of the gasification furnace Equipment,
A shift reaction device for generating hydrogen and carbon dioxide by supplying water vapor to the combustible gas that has passed through the char recovery device;
A carbon dioxide separation and recovery device for separating and recovering carbon dioxide from the combustible gas that has passed through the shift reaction device;
In a gasification system comprising: a carbon dioxide supply device that supplies a part of the carbon dioxide recovered by the carbon dioxide separation and recovery device as a transfer gas for the carbon-based solid raw material and supplies the carbon-based solid raw material as a transfer gas for the char ,
A first water vapor supply pipe for supplying water vapor to the gasification chamber of the gasification furnace;
The first water vapor supply pipe includes a first supply amount adjusting device that adjusts the supply amount of the water vapor according to a discharge amount of the char discharged from the gasification chamber and a gas temperature of the gasification chamber. A gasification system comprising: A second water vapor supply pipe for supplying water vapor to the throttle portion;
2. The second water vapor supply pipe includes a second supply amount adjusting device that adjusts the supply amount of the water vapor in accordance with a gas temperature in the vicinity of the throttle portion or the throttle portion. The gasification system described in 1.   The first and second supply amount adjusting devices are configured such that a sum of a supply amount of water vapor supplied to the gasification chamber and the throttle unit and a supply amount of water vapor supplied to the shift reaction device becomes a set flow rate. The gasification system according to claim 2, wherein the gasification system is adjusted.

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