JP2015109767A - Power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently utilize hydrogen that is generated as a by-product in a plant, while maintaining power generation efficiency of a gas turbine generator.SOLUTION: A power generation system 100 includes: a gas turbine generator 110 which converts rotation energy into power, the rotation energy being obtained by rotating a turbine 116 with a post-combustion gas generated by combusting a fuel; a carbon-dioxide recovery part 120 for recovering carbon dioxide from the post-combustion gas exhausted from the gas turbine generator 110; and a methane manufacturing device 150 for manufacturing methane while using the carbon dioxide recovered by the carbon-dioxide recovery part 120 and hydrogen as raw material gas. The gas turbine generator 110 uses the methane manufactured by the methane manufacturing device 150 as a part or all of the fuel.

Description

  The present invention relates to a power generation system including a gas turbine generator.

  In plants such as chemical plants and steel manufacturing plants, hydrogen is generated as a by-product. In order to effectively use hydrogen generated as a by-product, conventionally, hydrogen is combusted, for example, as a heat source for generating water vapor.

  In addition, in order to effectively use hydrogen as a by-product, a gas turbine generator rotated by a post-combustion gas generated as a result of burning natural gas and a steam turbine generator rotated by steam are combined. In a combined cycle power generation system (for example, Patent Document 1), a configuration in which hydrogen is added to natural gas and burned is also being studied.

JP 2013-144948 A

  In the combined cycle power generation system, by adding hydrogen to the natural gas, the consumption of the natural gas can be reduced by the amount of the added hydrogen, and it becomes possible to generate power at a low cost. However, since the main component of natural gas is hydrocarbon (methane), gas turbine generators are designed based on the calorific value of the post-combustion gas that results from burning hydrocarbons and do not affect power generation efficiency. When hydrogen exceeding a predetermined allowable amount is added, combustion becomes incomplete, and the amount of heat of the gas after combustion may be different from the case where only hydrocarbons are burned, resulting in a reduction in power generation efficiency.

  Therefore, in view of such problems, the present invention has an object to provide a power generation system capable of efficiently using hydrogen generated as a by-product in a plant while maintaining the power generation efficiency of a gas turbine generator. Yes.

  In order to solve the above-described problems, a power generation system according to the present invention includes a gas turbine generator that converts rotational energy obtained by rotating a turbine with a post-combustion gas generated by burning fuel into electric power, and a gas turbine. A carbon dioxide recovery unit that recovers carbon dioxide from the burned gas discharged from the generator, a carbon dioxide recovery unit that recovers carbon dioxide, and a methane production device that produces methane using hydrogen as a source gas. The gas turbine generator uses methane produced by a methane production apparatus as part or all of the fuel.

  In addition, the water is heated by reaction heat generated in the process of producing methane in the methane production apparatus by heating the water with the gas after combustion discharged from the gas turbine generator to produce water vapor. A second steam generation unit that generates steam, a steam turbine generator that converts rotational energy obtained by rotating the turbine with the steam generated by the first steam generation unit and the steam generated by the second steam generation unit into electric power And may be further provided.

  The methane production apparatus communicates a plurality of reactors containing a catalyst for promoting a methanation reaction, which is a reaction from raw material gas to methane, and two adjacent reactors in the plurality of reactors, respectively. A plurality of communication passages for sending the product gas generated in the reactor in the subsequent reactor to the subsequent reactor, and the raw material gas is introduced into the foremost reactor among the plurality of reactors, A cooling unit that cools the product gas generated in the preceding reactor to a temperature that is higher than the temperature at which the methanation reaction starts and lower than the temperature at which the methanation reaction stops, and at least one of the communication passages, A water removal unit that removes water from the product gas cooled by the cooling unit may be further provided between the reactor and the reactor.

  The methane production apparatus communicates a plurality of reactors containing a catalyst for promoting a methanation reaction, which is a reaction from raw material gas to methane, and two adjacent reactors in the plurality of reactors, respectively. A plurality of communication passages for sending the product gas generated in the reactor in the reactor to the reactor in the subsequent stage, and the raw material gas is introduced into the reactor in the earliest stage among the plurality of reactors, and the reaction in the earliest stage A water vapor introduction part for introducing water vapor into the vessel, and a cooling part for cooling the product gas generated in the preceding reactor in the communication path to a temperature higher than the temperature at which the methanation reaction starts and lower than the temperature at which the methanation reaction stops. , May be further provided.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to utilize efficiently the hydrogen produced as a by-product in a plant, maintaining the power generation efficiency of a gas turbine generator.

It is a figure for demonstrating the electric power generation system concerning embodiment. It is a figure explaining the specific structural example of a methane manufacturing apparatus. It is a figure explaining the specific structural example of the methane manufacturing apparatus concerning a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Power generation system 100)
FIG. 1 is a diagram for explaining a power generation system 100 according to the present embodiment. As shown in FIG. 1, the power generation system 100 includes a gas turbine generator 110, a carbon dioxide recovery unit 120, a methane production apparatus 150, an exhaust heat recovery boiler 160, a steam turbine generator 180, a cooler 190, And a pump 192 and a steam drum 194.

  The gas turbine generator 110 includes a compressor 112, a combustion unit 114, a turbine 116, and a generator 118, and is obtained by rotating the turbine 116 with a post-combustion gas generated by burning fuel. The generated rotational energy is converted into electric power.

  More specifically, the compressor 112 is connected to the turbine 116 through a rotating shaft, is rotated by the rotation of the turbine 116, compresses air, and sends the compressed air to the combustion unit 114. The combustion unit 114 mixes the air compressed by the compressor 112 and fuel (natural gas or the like) and burns it to generate a post-combustion gas. The turbine 116 is rotated by the post-combustion gas generated in the combustion unit 114, and the rotational energy obtained by the rotation is transmitted to the compressor 112 and the generator 118 through the rotation shaft. The generator 118 converts the rotational energy transmitted from the turbine 116 into electric power.

  The carbon dioxide recovery unit 120 includes, for example, an amine absorption tower and a regeneration tower, and recovers carbon dioxide from the post-combustion gas discharged from the gas turbine generator 110. A part of the carbon dioxide recovered by the carbon dioxide recovery unit 120 is introduced into the methane production apparatus 150, and a surplus is stored. Further, the burned gas after carbon dioxide recovery is exhausted to the outside after being subjected to a desulfurization treatment or the like.

  Although a detailed configuration will be described later, the methane production apparatus 150 produces methane using carbon dioxide recovered by the carbon dioxide recovery unit 120 and hydrogen as source gases.

  In a plant (chemical plant or iron manufacturing plant) where the power generation system 100 is installed, hydrogen is often generated as a by-product. In order to effectively use such hydrogen, it is conceivable to introduce the hydrogen directly into the combustion section 114 of the gas turbine generator 110 together with natural gas. However, the gas turbine generator 110 is generally designed based on the calorific value of the post-combustion gas generated as a result of burning only natural gas, and adds more hydrogen than a predetermined allowable amount that does not affect the power generation efficiency. Then, combustion becomes incomplete, and the amount of heat of the gas after combustion may not rotate as designed unlike the case where only the hydrocarbon is burned.

  Therefore, the methane production apparatus 150 according to the present embodiment produces methane with hydrogen generated as a by-product, and sends the methane to the combustion unit 114 of the gas turbine generator 110. The gas turbine generator 110 uses methane produced by the methane production apparatus 150 as part or all of the fuel.

  As described above, the gas turbine generator 110 is designed based on the amount of heat of the post-combustion gas generated as a result of burning natural gas. Since the main component of natural gas is methane, the power generation efficiency of the gas turbine generator 110 can be maintained at the designed efficiency by using methane produced by the methane production apparatus 150 as a fuel.

  In the present embodiment, the methane production apparatus 150 produces methane using hydrogen produced as a by-product in the plant, that is, surplus hydrogen, and uses the methane in the gas turbine generator 110. ing. Thereby, it becomes possible to utilize hydrogen efficiently.

  The exhaust heat recovery boiler 160 (first steam generation unit) includes a storage unit 162, an economizer 164, a steam drum 166, an evaporator 168, and a superheater 170.

  The storage unit 162 is disposed between the gas turbine generator 110 and the carbon dioxide recovery unit 120, temporarily stores the post-combustion gas discharged from the gas turbine power generator 110, and converts the heat of the post-combustion gas into the economizer 164. After the heat exchange with the steam drum 166 and the evaporator 168, the heat is discharged to the carbon dioxide recovery unit 120. The inlet of the accommodating part 162 becomes a high temperature of about 1000 ° C., for example.

  The economizer 164 is provided on the most downstream side (low temperature side) in the accommodating portion 162, heats water with the heat of the post-combustion gas flowing through the accommodating portion 162, and sends it to the steam drum 166.

  Both ends of the evaporator 168 are connected to the steam drum 166, and water is introduced into the evaporator 168 from the steam drum 166. The evaporator 168 then heats the introduced water with the heat of the post-combustion gas that circulates in the accommodating portion 162 to generate water vapor. Then, the water vapor generated by the evaporator 168 is returned to the steam drum 166. The evaporator 168 is provided on the upstream side of the economizer 164 in the accommodating portion 162.

  The superheater 170 is provided on the most upstream side (high temperature side) of the accommodating portion 162, and the heat of the post-combustion gas flowing through the accommodating portion 162 is further heated by the steam delivered from the steam drum 166 to superheated steam ( Steam heated to a temperature higher than the boiling point). Further, not only the steam drum 166 but also the steam drum 194 is connected to the superheater 170, and the steam delivered from the steam drum 194 is further heated by the heat of the gas after combustion flowing in the accommodating portion 162. And superheated steam. As will be described in detail later, the steam drum 194 stores water vapor generated by heating water with reaction heat generated in the process of producing methane in the methane production apparatus 150.

  Thus, the superheated steam generated by the superheater 170 is sent to the steam turbine generator 180.

  The steam turbine generator 180 includes a turbine 182 and a generator 184, and uses rotational energy obtained by rotating the turbine 182 with superheated steam (steam) generated by the exhaust heat recovery boiler 160 as electric power. Convert. Specifically, the turbine 182 is rotated by the superheated steam generated by the exhaust heat recovery boiler 160, and the rotational energy obtained by the rotation is transmitted to the generator 184 through the rotation shaft. The rotational energy transmitted from 182 is converted into electric power.

  Then, the steam discharged from the steam turbine generator 180 is cooled by the cooler 190 and then sent to the economizer 164 by the pump 192 for reuse.

  Next, a specific configuration of the methane production apparatus 150 that produces methane using hydrogen generated as a by-product and carbon dioxide recovered by the carbon dioxide recovery unit 120 as a raw material gas will be described in detail.

(Methane production equipment 150)
FIG. 2 is a diagram for explaining a specific configuration example of the methane production apparatus 150. As shown in FIG. 2, the methane production apparatus 150 includes a plurality of reactors 210 (indicated by 210 a to 210 d in FIG. 2), a communication path 220, an evaporator 240, an economizer 250, and a water removal unit 260. The heating unit 270 and the purification unit 280 are included. Here, a methane production apparatus 150 (four-stage methane production apparatus 150) having four reactors 210 will be described as an example, but the number of reactors 210 is not limited, and at least two or more reactors 210 may be used. I just need it.

…式（１） Further, in the methane production apparatus 150 according to the present embodiment, a methanation reaction (formula (1) below) for producing methane from a raw material gas (hydrogen and carbon dioxide) proceeds.

... Formula (1)

  As shown in FIG. 2, two adjacent reactors 210 in the plurality of reactors 210 are connected by a communication path 220. Here, the reactor 210b is connected to the reactor 210a, the reactor 210c is connected to the reactor 210b, and the reactor 210d is connected to the reactor 210c.

  Each reactor 210 contains a catalyst that promotes a methanation reaction, which is a reaction from a raw material gas (hydrogen, carbon dioxide) to methane, and among the plurality of reactors 210, the reactor 210a in the foremost stage is included. When the raw material gas is introduced, first, product gas is produced in the reactor 210a. As described above, the communication path 220 communicates two adjacent reactors 210 in the plurality of reactors 210, and sends the product gas generated in the upstream reactor 210 to the downstream reactor 210. Therefore, the product gas generated in one reactor 210 is sent to the reactor 210 disposed in the next stage of the one reactor 210 through the communication path 220. Then, the methanation reaction further proceeds in the reactor 210 arranged in the next stage, and a produced gas having a methane concentration higher than that produced in the preceding reactor 210 is produced.

  Further, the communication path 220 is provided with an evaporator 240 and an economizer 250. The evaporator 240 and the economizer 250 are heat exchangers, function as a second steam generation unit, and generate water vapor by heating water with reaction heat generated in the process of producing methane.

  More specifically, both ends of the evaporator 240 are connected to the steam drum 194 (see FIG. 1), and water is introduced into the evaporator 240 from the steam drum 194. Then, the evaporator 240 performs heat exchange between the introduced water and the generated gas flowing through the communication path 220, thereby cooling the generated gas and heating the water to generate water vapor. Then, the water vapor generated by the evaporator 240 is returned to the steam drum 194.

  Water is introduced into the economizer 250 from a pump 192 (see FIG. 1), and heat is exchanged between the product gas cooled by the evaporator 240 and water, thereby cooling the product gas and heating the water, Heated water is delivered to the steam drum 194.

  Then, the steam generated by the evaporator 240 and the economizer 250 is stored in the steam drum 194, then becomes superheated steam in the superheater 170 together with the steam stored in the steam drum 166, and is used in the steam turbine generator 180. The Rukoto. Thus, by generating water vapor by heating water with the reaction heat generated in the process of producing methane, water vapor can be generated without discarding the reaction heat generated in the methanation reaction, and thermal energy Can be used efficiently.

  On the other hand, the product gas is cooled by the evaporator 240 and the economizer 250 to a temperature at which the methanation reaction starts (here, 200 ° C.). That is, it can be said that the evaporator 240 and the economizer 250 also function as a cooling unit. In addition, since the catalyst is not accommodated in the communication path 220, when the evaporator 240 and the economizer 250 cool the product gas in the communication path 220, the methanation reaction does not proceed.

  With the configuration including the evaporator 240 and the economizer 250, the temperature of the reaction field in the reactor 210 arranged in the next stage can be lowered, and the production efficiency of methane (reaction rate of methanation reaction) can be increased. It becomes. Here, the reaction rate refers to the ratio of the raw material gas consumed by the methanation reaction to the introduced amount of the raw material gas, and is also referred to as the conversion rate.

  Further, a water removal unit 260 and a heating unit 270 are provided downstream of the evaporator 240 and the economizer 250 in the communication path 220 that connects the reactor 210c and the reactor 210d. The water removing unit 260 includes a condensing unit 262 and a gas / liquid separating unit 264. The condensing unit 262 cools the product gas produced in the reactor 210c to the water condensation temperature (dew point) to condense the water. The gas-liquid separation unit 264 separates the condensed water from the product gas cooled by the condensing unit 262.

  With the configuration including the water removing unit 260, the amount of water in the product gas generated in the reactor 210c can be reduced. When the amount of water in the product gas decreases, the equilibrium state of the methanation reaction is disrupted, and the reaction from the left side to the right side of the above formula (1) is promoted (the equilibrium moves to the right), and the methanation reaction It is possible to improve the reaction rate (production efficiency of methane). Thereby, compared with the structure which is not equipped with the water removal part 260, methanation reaction can be promoted in the reactor 210d.

  The heating unit 270 disposed downstream of the water removal unit 260 heats the water-removed gas, which is a product gas after the condensed water is removed, to a temperature at which the methanation reaction starts by the gas-liquid separation unit 264. To do.

  The purification unit 280 includes a condensing unit 282 and a gas / liquid separation unit 284. The condensing unit 282 cools the product gas generated in the reactor 210d to the water condensation temperature (dew point) to condense the water. The gas-liquid separator 284 separates the condensed water from the product gas cooled by the condenser 282 to produce methane.

  The methane thus produced is introduced into the gas turbine generator 110.

  As described above, according to the power generation system 100 according to the present embodiment, it is possible to efficiently use hydrogen generated as a by-product in the plant while maintaining the power generation efficiency of the gas turbine generator 110.

(Modification of methane production equipment)
In the above embodiment, the configuration in which the power generation system 100 includes the methane production apparatus 150 including the water removal unit 260 has been described as an example. However, the configuration of the methane production apparatus is not limited, and the water removal unit 260 is not necessarily provided. Hereinafter, the structure which can manufacture methane efficiently, without providing the water removal part 260 is demonstrated.

  FIG. 3 is a diagram illustrating a specific configuration example of the methane production apparatus 350 according to the modification. As shown in FIG. 3, the methane production apparatus 350 includes a steam introduction unit 360, a plurality of reactors 210 (indicated by 210 a to 210 c in FIG. 3), a communication path 220, an evaporator 240, and an economizer 250. And a purification unit 280. In addition, about the component substantially equivalent to the methane production apparatus 150 mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted, and here the water vapor | steam introduction part 360 from which a structure differs is explained in full detail. In addition, here, a methane production apparatus 350 having three reactors 210 (a three-stage methane production apparatus 350) will be described as an example, but the number of reactors 210 is not limited, and at least two or more reactors 210 may be used. I just need it.

  The water vapor introducing unit 360 introduces water vapor into the foremost reactor 210a. If it does so, water vapor | steam will be introduce | transduced into the reactor 210a with source gas.

  By introducing water vapor, the heat capacity in each reactor 210 can be increased, and the temperature increase per unit time of the reaction field in each reactor 210 can be suppressed. Since the methanation reaction is an exothermic reaction, the reaction rate can be improved by suppressing the temperature rise in the reaction field.

  Thus, according to the methane production apparatus 350 according to the modified example, methane can be produced with high efficiency with a simple configuration in which water vapor is introduced together with the raw material gas.

  In addition, since water vapor can be condensed into a liquid at less than 100 ° C., it can be easily separated from the product gas. Furthermore, since water vapor does not contain carbon, carbon does not deposit on the catalyst, and a situation in which the catalyst deteriorates can be avoided.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the embodiment and the modification described above, the power generation system 100 is configured to include the methane production apparatus 150 including the water removal unit 260 or the methane production apparatus 350 including the water vapor introduction unit 360. And explained. However, the configuration of the methane production apparatus is not limited as long as methane can be produced from hydrogen and carbon dioxide. For example, the water removing unit 260 and the water vapor introducing unit 360 may not be provided, or both the water removing unit 260 and the water vapor introducing unit 360 may be provided.

  Moreover, in the said embodiment and modification, the evaporator 240 and the economizer 250 which are heat exchangers are used as a 2nd water vapor | steam production | generation part which heats water with the reaction heat produced in the process of manufacturing methane, and produces | generates water vapor | steam. Explained with an example. However, the heat exchanger can also be used as a superheater depending on the temperature of the reaction heat.

  Moreover, in the said embodiment, although the electric power generation system 100 demonstrated the structure provided with two steam drums (steam drum 166, steam drum 194), it was provided with one steam drum, economizers 164 and 250, and evaporators 168 and 240. However, it may be connected to the one steam drum.

  Moreover, in the said embodiment, although the water removal part 260 comprised by the condensation part 262 and the gas-liquid separation part 264 was demonstrated, if water can be removed from product gas, there will be no limitation in the structure of the water removal part 260. For example, the water removal unit 260 may be configured with a water separation membrane or the like. In addition, when the water removal part 260 is comprised with the condensation part 262 and the gas-liquid separation part 264, the condensation part 262 functions as a cooling part, but when the water removal part 260 is comprised with a water separation membrane etc., it is separately cooled. It is good to have a part.

  Moreover, in the said embodiment, the evaporator 240 and the economizer 250 which function as a cooling part demonstrated and demonstrated the structure which cools produced | generated gas to the minimum temperature which a methanation reaction starts. However, the evaporator 240 and the economizer 250 functioning as a cooling unit cool the product gas to a temperature equal to or higher than the minimum temperature at which the methanation reaction starts and below the temperature at which the methanation reaction stops (the methanation reaction reaches equilibrium). That's fine.

  In the above embodiment, the heating unit 270 heats the gas after water removal to the lowest temperature at which the methanation reaction starts, but the temperature is higher than the lowest temperature at which the methanation reaction starts, May be heated to a temperature below that at which the reaction stops (the methanation reaction reaches equilibrium).

  Moreover, in the said embodiment, in order that the water vapor | steam introduction part 360 may increase the heat capacity of the reactor 210, the structure which introduce | transduces water vapor | steam was demonstrated. However, the heat capacity of the reactor 210 can be increased, and if it is condensed below 200 ° C., there is no limitation on the gas introduced by the water vapor introducing unit 360. For example, a halogen-based gas such as chlorofluorocarbon may be used.

  The present invention can be used in a power generation system including a gas turbine generator.

DESCRIPTION OF SYMBOLS 100 Power generation system 110 Gas turbine generator 120 Carbon dioxide collection part 150, 350 Methane production apparatus 160 Waste heat recovery boiler (1st water vapor production part)
180 Steam turbine generator 210 Reactor 220 Communication path 240 Evaporator (second steam generation unit, cooling unit)
250 economizer (second water vapor generation unit, cooling unit)
260 Water removal part 360 Water vapor introduction part

Claims (4)

A gas turbine generator that converts rotational energy obtained by rotating a turbine with a post-combustion gas generated by burning fuel into electric power;
A carbon dioxide recovery unit for recovering carbon dioxide from the burned gas discharged from the gas turbine generator;
A methane production apparatus for producing methane using carbon dioxide recovered by the carbon dioxide recovery unit and hydrogen as a source gas;
With
The gas turbine generator uses methane produced by the methane production apparatus as part or all of the fuel. A first water vapor generating unit that generates water vapor by heating water with the post-combustion gas discharged from the gas turbine generator;
A second water vapor generation unit that generates water vapor by heating water with reaction heat generated in the process of producing the methane in the methane production apparatus;
A steam turbine generator that converts rotational energy obtained by rotating the turbine with the steam generated by the first steam generating section and the steam generated by the second steam generating section into electric power;
The power generation system according to claim 1, further comprising: The methane production apparatus is
A plurality of reactors containing a catalyst for promoting a methanation reaction that is a reaction from the source gas to the methane;
A plurality of communication passages for communicating two adjacent reactors in the plurality of reactors, respectively, and sending the product gas generated in the former reactor to the latter reactor;
With
The source gas is introduced into the foremost reactor among the plurality of reactors,
A cooling section that cools the product gas generated in the preceding reactor in the communication path to a temperature equal to or higher than a temperature at which the methanation reaction starts and lower than a temperature at which the methanation reaction stops;
A water removal unit that removes water from the product gas cooled by the cooling unit between the cooling unit and the downstream reactor in at least one of the communication paths;
The power generation system according to claim 1, further comprising: The methane production apparatus is
A plurality of reactors containing a catalyst for promoting a methanation reaction that is a reaction from the source gas to the methane;
A plurality of communication passages for communicating two adjacent reactors in the plurality of reactors, respectively, and sending the product gas generated in the former reactor to the latter reactor;
With
The source gas is introduced into the foremost reactor among the plurality of reactors,
A water vapor introduction part for introducing water vapor into the most upstream reactor,
A cooling section that cools the product gas generated in the preceding reactor in the communication path to a temperature equal to or higher than a temperature at which the methanation reaction starts and lower than a temperature at which the methanation reaction stops;
The power generation system according to claim 1, further comprising:

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