JP2018087501A - Control device of hybrid power system, hybrid power system, control method of hybrid power system, and control program of hybrid power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a hybrid power system that restricts the consumption of the prescribed fuel gas which is a startup fuel while being capable of executing the stable startup in the startup of the hybrid power system having a fuel cell with biogas as fuel material gas.SOLUTION: A control device 70 of a hybrid power system 1 that includes: a SOFC10 with biogas 20 as fuel material gas; a MGT80 which is operated using exhaust fuel material gas which is discharged from the SOFC10; and a concentration meter 21 for measuring the methane concentration in the biogas 20. In a start-up process of the MGT80, when starting, supply of city gas 30 to the MGT80 is started, the supply start time of the biogas 20 supplied to the MGT80, the supply flow rate, and the supply flow rate of the city gas 30 are determined in accordance with the temperature rise rate of the power generation chamber temperature T1 per unit time and the methane concentration in the biogas 20, so as to switch the fuel of the MGT80 from the city gas 30 to the biogas 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combined power generation system control device, a combined power generation system, a combined power generation system control method, and a combined power generation system control program using a methane concentration variation gas.

  A fuel cell is a power generation device that uses a power generation method based on an electrochemical reaction, and has excellent power generation efficiency and environmental characteristics. Among these, solid oxide fuel cells (hereinafter referred to as “SOFC”) use ceramics such as zirconia ceramics as an electrolyte, hydrogen, carbon monoxide, hydrocarbon gases such as methane, coal, etc. The fuel cell is operated using as a fuel raw material gas a gas produced by a gasification facility for carbonaceous raw materials, city gas, natural gas, or a mixed gas containing a plurality of these components. Such a SOFC has been developed as a combined power generation system combined with an internal combustion engine such as a micro gas turbine (hereinafter referred to as “MGT”), and supplies compressed air discharged from the compressor to the air electrode of the SOFC. In addition, high-temperature exhaust fuel material gas discharged from the SOFC is supplied to the MGT combustor for combustion, and the turbine is rotated by the combustion gas generated in the combustor, thereby enabling power generation with high power generation efficiency. ing.

In recent years, it has been studied to use biogas instead of the above-mentioned fuel source gas for SOFC. Biogas is a gas derived from, for example, sewage, obtained by methane fermentation treatment from sewage, and main components are methane and carbon dioxide. In general, the methane concentration in the biogas is about 60% by volume and the carbon dioxide concentration is about 40% by volume. However, the methane concentration in the biogas is not constant and varies depending on the time zone and the season.
In SOFC, as a method for dealing with a change in methane concentration in biogas, Patent Document 1 discloses that a methane gas component in biogas is concentrated by using a pretreatment device in a pre-stage to be supplied to a fuel cell, and the methane concentration is kept constant. It is disclosed to supply after. Further, Patent Document 2 discloses that a necessary fuel source gas supply amount is calculated based on the methane concentration to control the supply amount. Patent Document 3 discloses that biogas is stored in an adsorption storage container and carbon dioxide is adsorbed, and the variation of the composition is dealt with by varying the output of the SOFC.

Japanese Patent Laid-Open No. 11-126629 JP 2003-331897 A JP 2008-153149 A

However, in the invention disclosed in Patent Document 1, there is a problem that the concentration of the methane gas component is costly, such as the installation of a power source and a pretreatment device, and the space required.
Moreover, in the invention disclosed in Patent Document 2, even if the supply flow rate is adjusted according to the methane concentration of the biogas that is the fuel raw material gas, the biogas has a lower combustion speed than the predetermined fuel gas, In MGT, there was a problem that the flame was not stabilized and misfired, making it difficult to start the combined power generation system.
Further, the invention disclosed in Patent Document 3 has a problem that the SOFC output is not stable because the SOFC output is changed in response to the change in the methane concentration of the biogas.

  The present invention solves the above-described problems, and in the start-up of a combined power generation system equipped with an SOFC using biogas as a fuel raw material gas, stable start-up is performed even for biogas with unstable methane concentration. An object of the present invention is to provide a combined power generation system control device, a combined power generation system, a combined power generation system control method, and a combined power generation system control program capable of reducing the consumption of a predetermined fuel gas that is a starting fuel. .

In order to solve the above problems, the combined power generation system control device, the combined power generation system, the combined power generation system control method, and the combined power generation system control program of the present invention employ the following means.
A control device for a combined power generation system according to the first aspect of the present invention includes a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring a power generation chamber temperature, and generates a methane concentration variation gas whose methane concentration varies during operation. A combined power generation system comprising: a fuel cell as fuel; a gas turbine operated using exhaust fuel gas discharged from the fuel cell; and a densitometer that measures the methane concentration in the methane concentration variation gas A gas turbine methane concentration variation gas supply line for supplying the methane concentration variation gas to the gas turbine, and a gas turbine predetermined fuel gas supply line for supplying a predetermined fuel gas. In the start-up process of the turbine, the supply of the predetermined fuel gas to the gas turbine is started together with the start-up, and the power generation chamber temperature measured by the power generation chamber temperature sensor A supply start time, a supply flow rate, and a supply flow rate of the predetermined fuel gas to be supplied to the gas turbine are determined according to a temperature increase rate per unit time and the methane concentration of the methane concentration change gas. The fuel of the gas turbine is switched from the predetermined fuel gas to the methane concentration variation gas.

In a gas turbine startup process that is performed prior to the start of power generation along with the startup temperature rise of a fuel cell such as a solid oxide fuel cell, first, a predetermined fuel gas such as city gas is supplied to the combustor. The compressed air discharged from the activated gas turbine is supplied to the air electrode of the fuel cell, so that the power generation chamber temperature of the fuel cell rises. According to the temperature increase rate per unit time of the power generation chamber temperature and the methane concentration of the methane concentration variation gas, the time, the supply flow rate, and the timing for starting the supply of the methane concentration variation gas supplied to the gas turbine by the control device, and The supply flow rate of the predetermined fuel gas is determined.
According to this configuration, only the predetermined fuel gas is supplied to the combustor in the start-up process of the gas turbine, so that the methane concentration fluctuating gas whose methane concentration fluctuates and whose combustion speed is slower than the predetermined fuel gas is not used. The turbine can be stably started, and the gas turbine flame is stabilized, whereby misfire of the gas turbine can be prevented.

In addition, since the supply start time of the methane concentration variation gas is determined according to the rate of temperature increase of the power generation chamber temperature of the fuel cell, the methane concentration is determined at an appropriate supply timing in a state where combustion in the combustor of the gas turbine is stable. The supply of the variable gas can be started. Further, since the supply of the predetermined fuel gas is stopped in a state where the combustion of the gas turbine is stable, the supply flow rate of the predetermined fuel gas can be reduced and minimized to be switched to the exhaust fuel raw material gas of the fuel cell. Can save the consumption. In addition, since the gas turbine can be appropriately started and the gas turbine can be started quickly, the fuel cell can be started quickly.
In addition, a methane concentration variation gas supply line for gas turbine that supplies a methane concentration variation gas to the gas turbine and a predetermined fuel gas supply line for gas turbine that supplies a predetermined fuel gas are provided. Even if there is a fluctuation in the methane concentration of the methane concentration fluctuation gas, the methane concentration is kept within the predetermined concentration range by adjusting the supply flow rate of the methane concentration fluctuation gas according to the methane concentration and by adjusting the supply flow rate of the methane concentration fluctuation gas according to the methane concentration. Can be easily adjusted.
“Methane concentration fluctuation gas” means a gas whose methane concentration fluctuates during operation. For example, methane fermentation gas by anaerobic fermentation treatment (methane fermentation) of organic waste, anaerobic treatment of sewage sludge And biogas derived from digestion gas from methane, and high tan in which hydrogen derived from renewable energy is mixed with methane.
The “predetermined fuel gas” means a fuel gas whose calorific value has been adjusted to be substantially constant in advance, such as city gas whose methane concentration has been adjusted to be substantially constant.

  In the first aspect, the methane concentration variation gas that is the fuel raw material gas supplied to the gas turbine, and the methane concentration of the fuel raw material gas supplied to the gas turbine is 60% by volume or more, and Each supply flow rate of the predetermined fuel gas may be adjusted.

According to this configuration, the methane concentration variation gas and the predetermined fuel gas, which are the fuel raw material gas supplied to the gas turbine, so that the methane concentration of the fuel raw material gas supplied to the gas turbine falls within a predetermined concentration range of 60% by volume or more. Therefore, it is not necessary to concentrate the methane gas component of the methane concentration fluctuation gas in which the methane concentration fluctuates. Therefore, the cost required for concentration of methane gas components can be reduced.
Also, for example, when the supply flow rate is adjusted according to the methane concentration of the methane concentration fluctuation gas supplied to the gas turbine, the methane concentration fluctuation gas has a slow combustion speed. Is difficult. However, with this configuration, by adjusting the supply flow rate of the predetermined fuel gas corresponding to the change in the methane concentration of the methane concentration fluctuation gas, the combustion of the combustor can be stabilized and the gas turbine can be stably started. .

  In the first aspect, after the gas turbine is started, when the temperature of the power generation chamber exceeds a first threshold value, supply of the methane concentration varying gas to the fuel electrode of the fuel cell may be started.

  According to this configuration, when the temperature of the power generation chamber exceeds the first threshold, the supply of the methane concentration varying gas to the fuel electrode of the fuel cell is started, so the gas turbine is started and the temperature of the power generation chamber rises to a predetermined temperature. Then, after the operation of the gas turbine is stabilized, the supply of the methane concentration varying gas to the fuel cell can be started.

  In the first aspect, it is preferable that the supply of the methane concentration varying gas to the air electrode of the fuel cell is started when the power generation chamber temperature exceeds a second threshold value that is greater than the first threshold value.

  According to this configuration, when the temperature of the power generation chamber rises and exceeds the second threshold value, the supply of the methane concentration varying gas to the air electrode of the fuel cell is started. The temperature of the power generation chamber can be further increased by catalytic combustion of the catalyst component contained in the constituent material of the air electrode of the fuel cell.

  In the first aspect, when the methane concentration of the methane concentration variation gas is 60% by volume or more, the supply of the methane concentration variation gas to the air electrode of the fuel cell is made smaller than a second threshold value. You may start with a larger value.

  According to this configuration, when the methane concentration of the methane concentration variation gas is 60% by volume or more, the supply of the methane concentration variation gas to the air electrode of the fuel cell is started at a value smaller than the second threshold, that is, the air Since the supply of the methane concentration fluctuation gas to the electrode is accelerated, the start-up of the fuel cell can be accelerated.

  In the first aspect, when the initial combustion of the air electrode is not stable, when the power generation chamber temperature exceeds the second threshold value, the supply of the predetermined fuel gas is started before the supply of the methane concentration variation gas is started. It is good.

  According to this configuration, when the initial fuel of the air electrode is not stable, when the temperature of the power generation chamber exceeds the second threshold, the supply of the predetermined fuel gas is started before the supply of the methane concentration variation gas is started. Stabilize.

  In the first aspect, the fuel cell may be a solid oxide fuel cell.

  In the first aspect, the supply flow rate of the predetermined fuel gas may be increased when an abnormality occurs in the supply of the methane concentration fluctuation gas.

  According to this configuration, when an abnormality occurs in the supply of the methane concentration fluctuation gas, such as when the supply of the methane concentration fluctuation gas decreases, stops, or the methane concentration in the methane concentration fluctuation gas decreases, By increasing the supply flow rate, the predetermined fuel gas can be used as a reserve system for the methane concentration fluctuation gas. Thereby, the combined power generation system can be operated more stably. When operation with methane concentration fluctuation gas is difficult due to the stoppage or reduction of methane concentration fluctuation gas supply, the operation can be continued by switching the system from methane concentration fluctuation gas to the specified fuel gas. Improve productivity and availability.

  A combined power generation system according to a second aspect of the present invention includes a fuel electrode, an air electrode, and a power generation chamber temperature sensor that measures a power generation chamber temperature, and a methane concentration variation gas that varies in methane concentration during operation as a fuel raw material gas. A fuel cell that operates, a gas turbine that is operated using exhaust fuel source gas discharged from the fuel cell, a methane concentration variation gas supply line for a gas turbine that supplies the methane concentration variation gas to the gas turbine, and A predetermined fuel gas supply line for a gas turbine that supplies a predetermined fuel gas to the gas turbine, and the control device according to any one of the above.

  A control method for a combined power generation system according to a third aspect of the present invention includes a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring a power generation chamber temperature, and fuels a methane concentration variation gas whose methane concentration varies during operation. A composite comprising a fuel cell as a raw material gas, a gas turbine operated using exhaust fuel raw material gas discharged from the fuel cell, and a concentration meter for measuring the methane concentration in the methane concentration variation gas A control method for a power generation system, comprising: a methane concentration variation gas supply line for gas turbine that supplies the methane concentration variation gas to the gas turbine; and a predetermined fuel gas supply line for gas turbine that supplies a predetermined fuel gas; In the gas turbine startup process, the supply of the predetermined fuel gas is started together with the startup, and the unit time of the power generation chamber temperature measured by the power generation chamber temperature sensor Supply start time of the methane concentration varies gas supplied to the gas turbine in accordance with the methane concentration in temperature rise rate and the methane concentration varies gas or to determine the supply flow rate of the supply flow rate and the predetermined fuel gas.

  A control program for a combined power generation system according to a fourth aspect of the present invention includes a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring a power generation chamber temperature, and fuels a methane concentration variation gas whose methane concentration varies during operation. A composite comprising a fuel cell as a raw material gas, a gas turbine operated using exhaust fuel raw material gas discharged from the fuel cell, and a concentration meter for measuring the methane concentration in the methane concentration variation gas A control program for a power generation system, comprising: a methane concentration variation gas supply line for gas turbine that supplies the methane concentration variation gas to the gas turbine; and a predetermined fuel gas supply line for gas turbine that supplies a predetermined fuel gas; In the starting process of the gas turbine, the supply command of the predetermined fuel gas is started at the same time as starting, and the emission measured by the power generation chamber temperature sensor is started. Supply start time, supply flow rate, and supply flow rate of the predetermined fuel gas supplied to the gas turbine in accordance with a temperature increase rate per unit time of the room temperature and the methane concentration of the methane concentration change gas To decide.

According to the present invention, in starting the combined power generation system including the fuel cell, the control device switches the supply from the predetermined fuel gas supply to the methane concentration variable gas supply to the rate of increase per unit time of the power generation chamber temperature of the fuel cell. Therefore, even a combined power generation system using a methane concentration fluctuation gas having an unstable methane concentration can be stably started.
In addition, the consumption of the predetermined fuel gas used as the starting fuel can be reduced.

It is the schematic block diagram which showed the combined power generation system of this invention. It is a time chart in starting of the combined power generation system which concerns on one Embodiment of this invention. It is the time chart which showed opening and closing of each shut-off valve at the time of starting of the combined power generation system concerning one embodiment of the present invention. It is the time chart which showed the opening degree of each flow regulating valve at the time of starting of the combined power generation system concerning one embodiment of the present invention. 1 illustrates one aspect of a cell stack in a fuel cell of a combined power generation system according to an embodiment of the present invention. 1 illustrates one aspect of a SOFC module in a fuel cell of a combined power generation system according to an embodiment of the present invention. 1 shows one aspect of a cross-section of an SOFC cartridge in a fuel cell of a combined power generation system according to an embodiment of the present invention.

Hereinafter, an embodiment of a combined power generation system control device, a combined power generation system, a combined power generation system control method, and a combined power generation system control program according to the present invention will be described with reference to the drawings.
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a schematic configuration of a combined power generation system control device, a combined power generation system, a combined power generation system control method, and a combined power generation system control program according to the present embodiment.
As shown in FIG. 1, the combined power generation system 1 includes a solid oxide fuel cell (hereinafter referred to as SOFC) (fuel cell) 10, a micro gas turbine (hereinafter referred to as MGT) (gas turbine) 80. The generator 86 and the control device 70 are provided as main components. The combined power generation system 1 of this embodiment uses a methane concentration fluctuation gas 20 in which the methane concentration fluctuates during operation as a fuel raw material gas. Examples of the methane concentration variable gas 20 include biogas derived from methane fermentation gas by anaerobic fermentation treatment (methane fermentation) of organic waste, digestion gas by anaerobic treatment of sewage sludge, renewable energy origin, etc. In this embodiment, the biogas 20 is used. Further, the combined power generation system 1 of the present embodiment uses the predetermined fuel gas 30 as the starting fuel. The predetermined fuel gas 30 means a predetermined gas whose calorific value has been adjusted to be substantially constant in advance, and examples thereof include city gas whose methane concentration is adjusted to be substantially constant. In this embodiment, the city gas 30 is used. And

  The MGT 80 includes a compressor 84, a combustor 81, a turbine 83, a generator 86, and a regenerative heat exchanger 85, and the compressor 84, the turbine 83, and the generator 86 are coaxially connected so as to be integrally rotatable. . The compressor 84 compresses the taken-in air 5. The combustor 81 is discharged from the compressor 84 and supplied through the regenerative heat exchanger 85, the second flow rate adjustment valve 18, and the oxidizing gas discharge line 305, and the oxidizing gas discharged from the air electrode 113 of the SOFC 10. Exhaust air (exhaust oxidizing gas) supplied through the discharge line 305 and the shutoff valve 13 and exhaust fuel source gas exhausted from the fuel electrode 109 of the SOFC 10 and supplied through the fuel electrode fuel source gas discharge line 303 and the flow rate adjustment valve 15 And the biogas 20 supplied through the gas feed fuel gas supply line 309 and the flow rate adjusting valve 62 or the city gas 30 supplied through the flow rate adjusting valve 63 are mixed and burned. The oxidizing gas discharge line 305 is provided with a combustor inlet temperature sensor 14 that measures the combustor inlet air temperature T 0 in the vicinity of the combustor 81. The turbine 83 rotates when the exhaust gas (combustion gas) supplied from the combustor 81 undergoes adiabatic expansion. The generator 86 is provided coaxially with the turbine 83, and generates electricity when the turbine 83 is driven to rotate. A turbine inlet temperature sensor 82 for measuring the exhaust gas temperature is provided in the vicinity of the turbine 83. The regenerative heat exchanger 85 performs heat exchange between the exhaust gas discharged from the turbine 83 and the compressed air discharged from the compressor 84. The exhaust gas cooled by heat exchange with the compressed air is discharged to the outside through the chimney 90.

  The starter fuel is supplied to the combustor 81 through the fuel source gas supply line 309 for the gas turbine. In this embodiment, the starting fuel for the MGT 80 is the biogas 20 and the city gas 30. The gas raw material gas supply line 309 for the gas turbine includes a gas turbine methane concentration variation gas supply line (hereinafter referred to as a gas turbine biogas supply line) 307 that supplies the biogas 20, and a gas turbine that supplies the city gas 30. A predetermined fuel gas supply line (hereinafter referred to as a city gas supply line for gas turbine) 308 is joined. The gas turbine biogas supply line 307 branches from a methane concentration fluctuation gas supply line (hereinafter referred to as a biogas supply line) 310, which will be described later, and is arranged in order from the upstream side along the flow direction of the biogas 20 with the shutoff valve 52 and A flow rate adjustment valve 62 capable of adjusting the supply amount of the biogas 20 is provided. The city gas supply line 308 for the gas turbine branches from a predetermined fuel gas supply line (hereinafter referred to as city gas supply line) 311 to be described later, and the shut-off valve 53 and the city in order from the upstream side along the flow direction of the city gas 30. A flow rate adjustment valve 63 capable of adjusting the supply amount of the gas 30 is provided.

As will be described in detail later, the SOFC 10 shown in FIG. 1 is configured by accommodating an air electrode 113, a solid electrolyte 111, and a fuel electrode 109 in a pressure vessel 205 as shown in FIGS. A part of compressed air compressed by the compressor 84 as shown in FIG. 1 is supplied to the air electrode 113 through the air electrode oxidizing gas supply line 306 as an oxidizing gas. Power generation is performed by supplying a fuel raw material gas that contributes to a power generation reaction such as gas or biogas through the fuel electrode fuel raw material gas supply line 301. The SOFC 10 also includes a power generation chamber 215 and a power generation chamber temperature sensor 11 that measures a power generation chamber temperature T1 of the power generation chamber 215.
The oxidizing gas used in the SOFC 10 is a gas containing approximately 15% to 30% oxygen, and typically air is preferable, but in addition to air, a mixed gas of combustion exhaust gas and air, oxygen and air It is possible to use a mixed gas.

  An air electrode oxidizing gas supply line 306 is connected to the SOFC 10, and a part of the compressed air compressed by the compressor 84 is supplied to the introduction portion of the air electrode 113. The air electrode oxidizing gas supply line 306 includes a branch point to a heat exchanger bypass line 313 described later in order from the upstream side in the compressed air flow direction, a regenerative heat exchanger 85, and a fuel cell bypass line 312 described later. The flow control valve 17 which can adjust the supply amount of compressed air, the junction point with the heat exchanger bypass line 313, and the junction point with the air electrode fuel raw material gas supply line 302 mentioned later are provided. In addition, a heat exchanger bypass line 313 that is a line for bypassing the regenerative heat exchanger 85 from the upstream branch point of the regenerative heat exchanger 85 to the downstream junction point of the flow rate adjusting valve 17 is provided on this line. Is provided with a first flow rate adjustment valve 16 capable of adjusting the bypass amount of the compressed air. The fuel cell bypass line 312 is a line that bypasses the SOFC 10 and supplies a part of the compressed air discharged from the regenerative heat exchanger 85 to the combustor 81, and a second flow rate adjustment that can adjust the supply amount of the compressed air. A valve 18 is provided.

  An oxidizing gas discharge line 305 that discharges exhaust air (exhaust oxidizing gas) used in the air electrode 113 is connected to the SOFC 10. The oxidizing gas discharge line 305 is connected to the introduction portion of the combustor 81, and supplies exhaust air used at the air electrode 113 to the combustor 81. The oxidizing gas discharge line 305 is provided with a shutoff valve 13, a junction with the fuel cell bypass line 312, and a combustor inlet temperature sensor 14 in order from the upstream side in the exhaust air flow direction.

  In addition, a fuel electrode fuel source gas supply line 301 that supplies fuel source gas to the SOFC 10 is connected to the SOFC 10 at the introduction portion of the fuel electrode 109. The anode fuel raw material gas supply line 301 is a line in which a biogas supply line 310 that supplies the biogas 20 and a city gas supply line 311 that supplies the city gas 30 merge. The biogas supply line 310 is provided with a branch point with the concentration meter 21 and the gas turbine biogas supply line 307 and a shutoff valve 22 in order from the upstream side along the flow direction of the biogas 20. The concentration meter 21 measures the concentration of the methane concentration in the biogas 20. The city gas supply line 311 includes, in order from the upstream side in the flow direction of the city gas 30, a branch point to the air electrode fuel raw material gas supply line 302, a branch point to the gas turbine city gas supply line 308, and a shutoff valve 35. Is provided. Further, the fuel electrode fuel raw material gas supply line 301 includes a desulfurizer 23, a branch point to the air electrode fuel raw material gas supply line 302 in order from the upstream side in the flow direction of the fuel raw material gas, a flow rate adjusting valve 24, and a later-described. A junction with the recirculation line 304 is provided.

  A fuel electrode fuel source gas discharge line 303 for discharging the exhaust fuel source gas used in the fuel electrode 109 is connected to the SOFC. The fuel electrode fuel material gas discharge line 303 is connected to the introduction portion of the combustor 81, and supplies the exhaust fuel material gas used in the fuel electrode 109 to the combustor 81. The fuel electrode fuel feed gas discharge line 303 has a flow rate adjustment capable of adjusting the blower 12, the branch point to the recirculation line 304, and the supply amount of the exhaust fuel feed gas in order from the upstream side along the flow direction of the exhaust fuel feed gas. A valve 15 is provided. The recirculation line 304 is connected from the fuel electrode fuel raw material gas discharge line 303 to the fuel electrode fuel raw material gas supply line 301. By recirculating the exhaust fuel raw material gas discharged from the fuel electrode 109 to the fuel electrode 109, the unreacted fuel raw material gas contained in the exhaust fuel raw material gas is reused and used as a raw material for internal reforming. Water is supplied, and the sensible heat of the exhaust fuel source gas is used to raise the temperature of the fuel source gas supplied to the fuel electrode 109. The recirculation line 304 is joined with a reforming water supply line 314 for supplying pure water equivalent to pure water from outside the system when the raw material water used for internal reforming of the fuel raw material gas is insufficient. . The reforming water supply line 314 is provided with a reforming water supply device 41 and a blower 42 in order from the upstream side along the flow direction of the clean water 40.

  The air electrode fuel raw material gas supply line 302 branches from the city gas supply line 311 and joins the air electrode oxidizing gas supply line 306. The air electrode fuel raw material gas supply line 302 includes a shut-off valve 31, a desulfurizer 32, a junction from the fuel electrode fuel raw material gas supply line 301, and a city in order from the upstream side along the flow direction of the city gas and the fuel raw material gas. A flow rate adjustment valve 34 capable of adjusting the supply amount of the gas 30 or the biogas 20 is provided. A shutoff valve 33 is provided on a line connecting the fuel electrode fuel raw material gas supply line 301 and the air electrode fuel raw material gas supply line 302.

The control device 70 controls each shut-off valve and each flow rate adjustment valve based on, for example, the measured values of the densitometer 21 and the temperature sensors 11, 14, and 82.
The control device 70 includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), 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.

Next, a method for starting the combined power generation system according to this embodiment will be described with reference to FIGS.
FIG. 2 shows a time chart for starting the combined power generation system according to the present embodiment.
In the figure, the vertical axis indicates the power generation output of the MGT 80 and SOFC 10, the amount of fuel raw material gas supplied to the combustor 81, the amount of fuel raw material gas supplied to the fuel electrode 109, and the amount of fuel raw material gas supplied to the air electrode 113 from the top of the figure. , Each value of the combustor inlet air temperature T0, the power generation chamber temperature T1 of the power generation chamber 215, and the current load of the SOFC 10, and the horizontal axis is time. In the time chart of the power generation output, the one-dot chain line indicates the power generation output of the MGT 80, and the two-dot chain line indicates the power generation output of the SOFC 10. In each time chart of the combustor supply amount, the fuel electrode supply amount, and the air electrode supply amount, the solid line indicates the supply amount of the biogas 20, and the broken line indicates the supply amount of the city gas 30. Further, in the time chart of the air electrode supply amount, the one-dot chain line indicates the supply amount of the city gas 30 when the city gas 30 is supplied before the biogas 20 is supplied, and the two-dot chain line indicates the city gas 30 before the biogas 20 is supplied. The supply amount of the biogas 20 when is supplied is shown.
FIG. 3 is a time chart showing opening and closing of each shut-off valve when the combined power generation system according to this embodiment is started.
In the figure, the vertical axis represents the open / close (ON / OFF) states of the shutoff valve 53, shutoff valve 52, shutoff valve 35, shutoff valve 22, shutoff valve 31, shutoff valve 33, and shutoff valve 13 from the top of the figure, The horizontal axis is time. In the time chart of the shut-off valve 31, the broken line indicates the ON / OFF state of the shut-off valve 31 when the city gas 30 is supplied before the biogas 20 is supplied. In the time chart of the shutoff valve 33, the alternate long and short dash line indicates the ON / OFF state of the shutoff valve 33 when the city gas 30 is supplied before the biogas 20 is supplied.
FIG. 4 is a time chart showing the opening degree of each flow rate adjustment valve when the combined power generation system according to this embodiment is started.
In the figure, the vertical axis indicates the flow rate adjustment valve 63, the flow rate adjustment valve 62, the flow rate adjustment valve 24, the flow rate adjustment valve 34, the flow rate adjustment valve 15, the first flow rate adjustment valve 16, the flow rate adjustment valve 17, and the second from the top of the figure. It is each opening degree of the flow regulating valve 18, and a horizontal axis is time. In the time chart of the flow rate adjustment valve 34, the alternate long and short dash line indicates the opening degree of the flow rate adjustment valve 34 when the city gas 30 is supplied before the biogas 20 is supplied.

  In the method for starting the power generation system of this embodiment, the MGT 80 is started at time t1, as shown in FIG. At time t1, as shown in FIG. 3, all the shutoff valves are OFF (shutoff), and as shown in FIG. 4, all the flow rate regulating valves except the second flow rate regulating valve 18 are fully closed, and the second flow rate regulating valves. Only 18 is fully open.

  In starting up the MGT 80, supply of the city gas 30 to the combustor 81 is started. At time t1, as shown in FIG. 3, the shutoff valve 53 on the gas turbine city gas supply line 308 is turned on (opened), and the flow rate adjustment on the gas turbine city gas supply line 308 is adjusted as shown in FIG. The opening degree of the valve 63 is increased, and the supply amount of the city gas 30 to the combustor 81 is increased to a predetermined value. As soon as the supply amount of the city gas 30 rises to a predetermined value, the shut-off valve 13 on the oxidizing gas discharge line 305 is turned on as shown in FIG. 3, and the air oxidizing gas supply line 306 is turned on as shown in FIG. The second flow rate adjustment valve 18 on the fuel cell bypass line 312 is fully closed.

As indicated by the alternate long and short dash line in the power generation output chart on the vertical axis in FIG. 2, the power generation output of the MGT 80 gradually increases due to the supply of the city gas 30 to the combustor 81, and the power generation output of the generator 86 reaches a predetermined value. Reaches a constant output (rated output). Further, when the MGT 80 is activated, the combustor inlet air temperature T0 measured by the combustor inlet temperature sensor 14 and the power generation chamber temperature T1 measured by the power generation chamber temperature sensor 11 are increased. The control device 70 sequentially acquires the temperature increase rate per unit time of the power generation chamber temperature T1, and the combustion of the biogas 20 in the combustor 81 based on the power generation chamber temperature T1 and the temperature increase rate per unit time. Appropriately determining whether or not the situation is stable, the time t2 that is the timing for starting the supply of the biogas 20 to the combustor 81 is determined.
In other words, when the combined power generation system 1 is activated, it is necessary to perform activation within a specified time while maintaining the power generation chamber temperature T1 of the SOFC 10 and the temperature increase rate per unit time thereof. For this purpose, it is necessary to prevent misfire in the combustor 81 of the MGT 80 and perform stable combustion. From the simulation and test results, the power generation chamber temperature T1 that is the timing for starting the supply of the biogas 20 to the combustor 81 and A determination reference value for the rate of temperature increase per unit time is separately determined, and the time t2 is determined by reaching this determination reference value.

The supply of the biogas 20 to the combustor 81 at time t2, as shown by the flow rate of the biogas 20 to the gas turbine fuel feed gas supply line 309 by the solid line of the combustor supply amount chart on the vertical axis in FIG. To start. At this time, as shown in FIG. 3, the shut-off valve 52 on the gas turbine biogas supply line 307 is turned on, and the opening degree of the flow rate adjusting valve 62 on the gas turbine biogas supply line 307 as shown in FIG. Raise. Immediately after the supply to the combustor 81 is started, the flow rate of the biogas 20 is small. Therefore, if the concentration of the methane gas component contained in the biogas 20 (methane concentration) changes, the combustion stability in the combustor 81 is greatly affected. Therefore, the concentration meter 21 measures the amount of the methane gas component in the fuel raw material gas (in this case, the mixed fuel of the city gas 30 and the biogas 20) supplied to the combustor 81 so that the amount becomes a certain amount or more. The supply amount of the biogas 20 is changed according to the methane concentration. In accordance with this, the supply amount of the city gas 30 indicated by a broken line is changed.
Here, the amount of the methane gas component in the gas raw material gas supply line 309 for the gas turbine can be set to a certain amount or more by adjusting the methane concentration to be within a predetermined concentration range of 60% by volume or more. Although the predetermined concentration range of methane differs depending on the structure of the combustor 81 and the like, the predetermined concentration range in the present embodiment is, for example, 60 vol% to 65 vol%, and the city gas 30 is reduced by reducing the supply amount of the city gas 30 as much as possible. The methane concentration is set so that stable combustion can be obtained without consumption.
When the supply amount of the biogas 20 is gradually increased, and combustion is stabilized exceeding a predetermined value (for example, 300 ° C. to 400 ° C.) at which the combustor inlet air temperature T0 rises and does not misfire, as shown in FIG. The flow regulating valve 63 on the city gas supply line 308 is fully closed, and the shut-off valve 53 on the gas turbine city gas supply line 308 is turned off (shut off) as shown in FIG. The supply of 30 is stopped, and the flow rate of the city gas 30 becomes zero as shown by the broken line in the chart of the combustor supply amount on the vertical axis in FIG.

Next, when the power generation chamber temperature T1 exceeds a first threshold (for example, 300 ° C. to 450 ° C.), the control device 70 starts supplying the fuel raw material gas to the SOFC 10. At time t3 when the power generation chamber temperature T1 exceeds the first threshold, the shutoff valve 22 on the biogas supply line 310 is turned on as shown in FIG. 3, and the fuel electrode fuel raw material gas is shown in FIG. The opening degree of the flow rate adjustment valve 24 on the supply line 301 and the flow rate adjustment valve 15 on the anode electrode raw material gas discharge line 303 are increased. Thereby, the biogas 20 is supplied to the fuel electrode 109 of the SOFC 10 as indicated by the biogas flow rate in the fuel electrode fuel raw material gas supply line 301 by the solid line of the fuel electrode supply amount chart on the vertical axis in FIG.
At the time t3, the supply of the biogas 20 to the fuel electrode 109 of the SOFC 10 is started, and at the same time, the combustion of the MGT 80 by the fuel source gas supply line 309 for the gas turbine shown by the solid line of the combustor supply amount chart on the vertical axis in FIG. The amount of biogas 20 supplied to the vessel 81 is reduced (as shown in FIG. 4, the opening degree of the flow rate adjustment valve 62 on the gas turbine biogas supply line 307 starts to be reduced).

  Next, when the power generation chamber temperature T1 exceeds a second threshold (for example, 400 ° C. to 500 ° C., second threshold> first threshold), the controller 70 further increases the temperature of the power generation chamber 215 to increase the temperature of the SOFC 10. The supply of the biogas 20 to the air electrode 113 is started. At time t4 when the power generation chamber temperature T1 exceeds the second threshold, the shut-off valve 33 is turned on as shown in FIG. 3, and the flow rate adjustment on the air electrode fuel material gas supply line 302 as shown in FIG. The opening degree of the valve 34 is increased. As a result, the biogas 20 is supplied to the air electrode 113 of the SOFC 10 through the air electrode fuel material gas supply line 302 as indicated by the solid line of the air electrode supply amount chart on the vertical axis in FIG.

  Here, when the methane concentration of the biogas 20 measured by the densitometer 21 is 60% by volume or more, the temperature raising capability in catalytic combustion by the biogas 20 becomes high, so the power generation chamber temperature T1 reaches the second threshold value. The biogas 20 can be input even at a slightly lower temperature. The timing when the supply of the fuel raw material gas to the air electrode 113 of the SOFC 10 may start as a time t4 ′ when the power generation chamber temperature T1 exceeds a predetermined value smaller than the second threshold. In this case, since the time t4 ′ is smaller (earlier) than the time t4, the supply of the biogas 20 to the air electrode 113 of the SOFC 10 is accelerated.

  In addition, when it is found that the catalytic combustion of the air electrode 113 is not stable after confirming the operation a plurality of times, the city gas 30 may be supplied in advance prior to the supply of the biogas 20. Catalytic combustion is stabilized by supplying in advance the city gas 30 whose methane concentration is adjusted to be substantially constant. When the city gas 30 is supplied, the city gas 30 is supplied by the air electrode fuel material gas supply line 302 at time t4, as indicated by the one-dot chain line of the air electrode supply amount chart on the vertical axis in FIG. The biogas 20 is supplied to the air electrode 113. Further, the shut-off valve 31 is turned ON as shown by a broken line in the chart of the shut-off valve 31 in FIG. 3, and the opening degree of the flow regulating valve 34 corresponds to the city gas 30 as shown by the broken line in the chart of the flow regulating valve 34 in FIG. To a predetermined value. Further, after the predetermined time has elapsed, the shutoff valve 31 is turned off as shown by a broken line in the chart of the shutoff valve 31 in FIG. 3 to stop the supply of the city gas 30, and the shutoff valve 33 is shut off as shown by a one-dot chain line. The valve 33 is turned on to start supplying the biogas 20. As indicated by the broken line in the flow rate adjusting valve 34 chart of FIG. 4, after a predetermined time has elapsed, the opening degree of the flow rate adjusting valve 34 is further increased to a predetermined value corresponding to the biogas 20.

  When the power generation chamber temperature T1 reaches a predetermined value, the SOFC 10 starts power generation. At time t5 when the power generation of the SOFC 10 is started, the power generation output and the current load of the SOFC 10 start to rise as shown by the two-dot chain line in the power generation output chart on the vertical axis in FIG. 2 and the solid line in the current load chart. Accordingly, the supply amount of the fuel raw material gas, that is, the biogas 20, to the fuel electrode 109 of the SOFC 10 further increases as shown by the solid line in the fuel electrode supply amount chart. As shown in the chart of the flow rate adjustment valve 24 and the flow rate adjustment valve 15 in FIG. 4, the opening degree of the flow rate adjustment valve 24 and the flow rate adjustment valve 15 further increases.

Further, since the power generation chamber temperature T1 rises due to heat generation due to power generation due to an increase in current load, there is no need to raise the temperature by supplying the biogas 20 to the air electrode 113 of the SOFC 10 to cause catalytic combustion. The supply amount of the biogas 20 to the electrode 113 is reduced. As indicated by the solid line of the air electrode supply amount chart on the vertical axis in FIG. 2, the supply amount of the biogas 20 to the air electrode fuel material gas supply line 302 is reduced from time t5. Further, as shown by the solid line of the flow rate adjusting valve 34 in FIG. 4, the opening degree of the flow rate adjusting valve 34 on the air electrode fuel material gas supply line 302 is decreased from time t5, and the shutoff valve 33 in FIG. As shown by the solid line in the chart, the shutoff valve 33 is turned off at time t5, and the supply of the biogas 20 to the air electrode 113 is stopped.
In addition, as shown by the two-dot chain line in the power generation output chart on the vertical axis in FIG. 2, the air supplied from the air oxidizing gas supply line 306 to the air electrode 113 as the power generation of the SOFC 10 starts from time t5. The temperature of (oxidizing gas) is determined by adjusting the supply amount of compressed air discharged from the regenerative heat exchanger 85 shown in FIG. 4 and the bypass amount of compressed air bypassing the regenerative heat exchanger 85. (Supply amount) is adjusted by the degree of opening with the adjustable first flow rate adjusting valve 16, and the power generation chamber temperature T1 can be controlled to reach the predetermined temperature sooner.

  When the SOFC 10 reaches rated operation at time t6, the power generation output and current load of the SOFC 10 maintain substantially constant values as indicated by the two-dot chain line in the power generation output chart on the vertical axis and the solid line in the current load chart in FIG. . Further, as shown in the chart of T0 on the vertical axis and the chart of T1 on the vertical axis in FIG. 2, the combustor inlet air temperature T0 and the power generation chamber temperature T1 are also substantially constant values. When the SOFC 10 becomes rated operation at time t6, the control device 70 is configured so that the amounts of methane components in the biogas 20 supplied to the fuel electrode 109 of the SOFC 10 and the biogas 20 supplied to the combustor 81 are constant. Changes the supply amount of the biogas 20 according to the methane concentration measured by the densitometer 21. As shown in FIG. 4, the supply amount of the biogas 20 is adjusted by increasing or decreasing the opening degree of the flow rate adjusting valves 62, 24 and 15.

The city gas 30 used as the starting fuel for the combined power generation system 1 can also be used as a standby system when an abnormality occurs in the biogas system.
Specifically, when an abnormality occurs in the supply of the biogas 20, the shutoff valve 22 and the shutoff valve 52 are turned off and the supply of the biogas 20 is stopped. Further, the supply of the fuel raw material gas to the fuel electrode 109 and the combustor 81 of the SOFC 10 is switched from the biogas 20 to the city gas 30 by turning on the shutoff valve 35 and the shutoff valve 53. Thereby, a driving | operation can be continued without stopping the combined power generation system 1, and reliability and an operation rate improve.

Further, when the methane concentration of the biogas 20 decreases during the operation of the combined power generation system 1, the operation using only the biogas 20 as the fuel raw material gas is changed to the operation using the mixed fuel of the biogas 20 and the city gas 30. By switching, the methane concentration can be kept within a predetermined concentration range of a certain value (for example, 60% by volume) or more.
When the methane concentration of the biogas 20 is decreased in the operation of the biogas 20 alone, the SOFC 10 is stably operated due to the decrease in the voltage of the SOFC 10 and the S / C (steam carbon ratio), which is the ratio of reforming steam and carbon. In this case, it is difficult to prevent this by mixing the city gas 30 with the biogas 20 by monitoring with the densitometer 21.

Here, the SOFC 10 according to the present embodiment will be described below.
In the following, for convenience of explanation, the positional relationship of each component is specified using the expressions “upper” and “lower” on the basis of the paper surface, but this is not necessarily limited to the vertical direction. For example, the upward direction on the paper surface may correspond to the downward direction in the vertical direction. Moreover, you may respond | correspond to the horizontal direction where the up-down direction in a paper surface goes orthogonally to a perpendicular direction.
In the following, a cylindrical shape is described as an example of the cell stack of the SOFC 10, but it is not necessarily limited to this. For example, a flat cell stack may be used.

  First, a cylindrical cell stack according to the present embodiment will be described with reference to FIG. Here, FIG. 5 shows one mode of the cell stack according to the present embodiment. The cell stack 101 includes a cylindrical base tube 103, a plurality of fuel cells 105 formed on the outer peripheral surface of the base tube 103, and an interconnector 107 formed between adjacent fuel cells 105. The fuel cell 105 is formed by stacking a fuel electrode 109, a solid electrolyte 111, and an air electrode 113. Further, the cell stack 101 is connected to the air electrode 113 of the fuel cell 105 formed at the end of the base tube 103 in the axial direction among the plurality of fuel cells 105 formed on the outer peripheral surface of the base tube 103. A lead film 115 electrically connected via the interconnector 107, and a lead film (not shown) electrically connected to the fuel electrode 109 of the fuel cell 105 formed at the other end. Prepare.

The base tube 103 is made of a porous material, for example, CaO stabilized ZrO ₂ (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ + NiO), or Y ₂ O ₃ stabilized ZrO ₂ (YSZ), or MgAl ₂ O ₄ or the like is the main component. The base tube 103 supports the fuel cell 105, the interconnector 107, and the lead film 115, and supplies the fuel raw material gas supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103. It is diffused to the fuel electrode 109 formed on the outer peripheral surface of 103.

The fuel electrode 109 is made of an oxide of a composite material of Ni and a zirconia-based electrolyte material. For example, Ni / YSZ is used. The thickness of the fuel electrode 109 is 50 to 250 μm. In this case, in the fuel electrode 109, Ni which is a component of the fuel electrode 109 has a catalytic action on the fuel raw material gas (catalytic combustion). This catalytic action (catalytic combustion) reacts with a fuel raw material gas supplied through the base tube 103, for example, a mixed gas of methane (CH ₄ ) and water vapor, and hydrogen (H ₂ ) and carbon monoxide (CO ). Further, the fuel electrode 109 has an interface between the solid electrolyte 111 and hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming and oxygen ions (O ²⁻ ) supplied via the solid electrolyte 111. It reacts electrochemically in the vicinity to produce water (H ₂ O) and carbon dioxide (CO ₂ ). At this time, the fuel cell 105 generates electric power by electrons emitted from oxygen ions.
When the fuel source gas is supplied to the cell stack 101, an endothermic reaction occurs due to the above-described reforming reaction. Thereby, if the fuel raw material gas is increased, the power generation chamber temperature T1 is lowered.
Fuel source gases that can be used by supplying to the fuel electrode 109 of the SOFC 10 include hydrocarbon gases such as hydrogen (H ₂ ), carbon monoxide (CO), and methane (CH ₄ ), city gas, natural gas, and petroleum. , Gas produced from gasification equipment of carbonaceous raw materials such as methanol and coal gasification gas.

As the solid electrolyte 111, YSZ having gas tightness that prevents gas from passing and high oxygen ion conductivity at high temperature is mainly used. This solid electrolyte 111 moves oxygen ions (O ²⁻ ) generated at the air electrode 113 to the fuel electrode 109. The film thickness of the solid electrolyte 111 located on the surface of the fuel electrode 109 is 10 to 100 μm.

The air electrode 113 is made of, for example, a LaSrMnO ₃ oxide or a LaCoO ₃ oxide. The air electrode 113 generates oxygen ions (O ²⁻ ) by dissociating oxygen in an oxidizing gas such as air supplied near the interface with the solid electrolyte 111. The air electrode 113 may have a two-layer structure. In this case, the air electrode layer (air electrode intermediate layer) on the solid electrolyte 111 side is made of a material that exhibits high ionic conductivity and excellent catalytic activity. The air electrode layer (air electrode conductive layer) on the air electrode intermediate layer may be composed of a perovskite oxide represented by Sr and Ca-doped LaMnO ₃ . By doing so, the power generation performance can be further improved.

The interconnector 107 is made of a conductive perovskite oxide represented by M _1-x L _x TiO ₃ (M is an alkaline earth metal element, L is a lanthanoid element) such as SrTiO ₃ system. The interconnector 107 is a dense film so as not to mix the fuel raw material gas and the oxidizing gas, and has stable durability and electrical conductivity in both the oxidizing atmosphere and the reducing atmosphere. The interconnector 107 electrically connects the air electrode 113 of one fuel battery cell 105 and the fuel electrode 109 of the other fuel battery cell 105 in adjacent fuel battery cells 105 so that the adjacent fuel battery cells 105 are connected to each other. Are connected in series. Since the lead film 115 needs to have electronic conductivity and a thermal expansion coefficient close to that of the other materials constituting the cell stack 101, the lead film 115 is made of Ni such as Ni / YSZ and a zirconia-based electrolyte material. Composed of composite material. The lead film 115 leads the DC power generated by the plurality of fuel cells 105 connected in series by the interconnector 107 to the vicinity of the end of the cell stack 101.

  Next, the SOFC module and the SOFC cartridge according to this embodiment will be described with reference to FIGS. Here, FIG. 6 shows one mode of the SOFC module according to the present embodiment. FIG. 7 shows a cross-sectional view of one aspect of the SOFC cartridge according to the present embodiment.

As illustrated in FIG. 6, the SOFC module 201 includes, for example, a plurality of SOFC cartridges 203 and a pressure vessel 205 that stores the plurality of SOFC cartridges 203.
Although FIG. 6 illustrates a cylindrical SOFC cell stack, it is not necessarily limited to this, and for example, a flat cell stack may be used.
The SOFC module 201 includes a fuel source gas supply pipe 207, a plurality of fuel source gas supply branch pipes 207a, a fuel source gas discharge pipe 209, and a plurality of fuel source gas discharge branch pipes 209a. Further, the SOFC module 201 includes an oxidizing gas supply pipe (not shown), an oxidizing gas supply branch pipe (not shown), an oxidizing gas discharge pipe (not shown), and a plurality of oxidizing gas discharge branch pipes (not shown). Is provided.

  The fuel source gas supply pipe 207 is provided outside the pressure vessel 205 and is connected to a fuel source gas supply unit that supplies a fuel source gas having a predetermined gas composition and a predetermined flow rate corresponding to the power generation amount of the SOFC module 201. Are connected to a plurality of fuel source gas supply branch pipes 207a. The fuel raw material gas supply pipe 207 is configured to branch the fuel raw material gas having a predetermined flow rate supplied from the above-described fuel raw material gas supply unit into a plurality of fuel raw material gas supply branch pipes 207a. The fuel source gas supply branch pipe 207 a is connected to the fuel source gas supply pipe 207 and is connected to a plurality of SOFC cartridges 203. The fuel source gas supply branch pipe 207a guides the fuel source gas supplied from the fuel source gas supply pipe 207 to the plurality of SOFC cartridges 203 at a substantially equal flow rate, and makes the power generation performance of the plurality of SOFC cartridges 203 substantially uniform. Is.

  The fuel source gas discharge branch pipe 209a is connected to the plurality of SOFC cartridges 203 and is also connected to the fuel source gas discharge pipe 209. The fuel material gas discharge branch pipe 209a guides the exhaust fuel material gas discharged from the SOFC cartridge 203 to the fuel material gas discharge pipe 209. The fuel source gas discharge pipe 209 is connected to the plurality of fuel source gas discharge branch pipes 209 a and a part thereof is disposed outside the pressure vessel 205. The fuel raw material gas discharge pipe 209 guides the exhaust fuel raw material gas derived from the fuel raw material gas discharge branch pipe 209 a at a substantially equal flow rate to the outside of the pressure vessel 205.

  Since the pressure vessel 205 is operated at an internal pressure of 0.1 MPa to about 1 MPa and an internal temperature of atmospheric temperature to about 550 ° C., the pressure vessel 205 is resistant to corrosion and resistance to oxidizing agents such as oxygen contained in the oxidizing gas. The possessed material is used. For example, a stainless steel material such as SUS304 is suitable.

  Here, in the present embodiment, a mode has been described in which a plurality of SOFC cartridges 203 are assembled and stored in the pressure vessel 205. However, the present invention is not limited to this. It can also be set as the aspect accommodated in the container 205. FIG.

  As shown in FIG. 7, the SOFC cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel source gas supply chamber 217, a fuel source gas discharge chamber 219, an oxidizing gas supply chamber 221, and an oxidizing gas. A discharge chamber 223. The SOFC cartridge 203 further includes an upper tube plate 225a, a lower tube plate 225b, an upper heat insulator 227a, and a lower heat insulator 227b. In this embodiment, the SOFC cartridge 203 includes a fuel source gas supply chamber 217, a fuel source gas discharge chamber 219, an oxidizing gas supply chamber 221, and an oxidizing gas discharge chamber 223 as shown in FIG. Therefore, the fuel raw material gas and the oxidizing gas flow so as to face the inner side and the outer side of the cell stack 101, but this is not always necessary. For example, the inner side and the outer side of the cell stack are parallel to each other. Or oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack.

  The power generation chamber 215 is an area formed between the upper heat insulator 227a and the lower heat insulator 227b. The power generation chamber 215 is a region where the fuel cell 105 of the cell stack 101 is disposed, and is a region where electric power is generated by electrochemically reacting the fuel raw material gas and the oxidizing gas. Further, the temperature in the vicinity of the center of the power generation chamber 215 in the longitudinal direction of the cell stack 101 is monitored by the temperature sensor 11 or the like, and becomes a high temperature atmosphere of about 700 ° C. to 1000 ° C. during the steady operation of the SOFC module 201.

  The fuel source gas supply chamber 217 is a region surrounded by the upper casing 229a and the upper tube plate 225a of the SOFC cartridge 203, and the fuel source gas supply hole 231a provided in the upper portion of the upper casing 229a supplies fuel source gas. It communicates with the branch pipe 207a. The plurality of cell stacks 101 are joined by an upper tube plate 225a and a seal member 237a, and the fuel source gas supply chamber 217 is fuel supplied from the fuel source gas supply branch pipe 207a through the fuel source gas supply hole 231a. Is guided to the inside of the base tube 103 of the plurality of cell stacks 101 at a substantially uniform flow rate, so that the power generation performance of the plurality of cell stacks 101 is made substantially uniform.

  The fuel source gas discharge chamber 219 is an area surrounded by the lower casing 229b and the lower tube plate 225b of the SOFC cartridge 203, and the fuel source gas discharge branch pipe is formed by the fuel source gas discharge hole 231b provided in the lower casing 229b. 209a. The plurality of cell stacks 101 are joined by the lower tube plate 225b and the sealing member 237b, and the fuel source gas discharge chamber 219 passes through the inside of the base tube 103 of the plurality of cell stacks 101, and the fuel source gas discharge chamber 219. The exhaust fuel source gas supplied to the fuel can be collected and led to the fuel source gas discharge branch pipe 209a through the fuel source gas discharge hole 231b.

  Corresponding to the power generation amount of the SOFC module 201, a predetermined gas composition and a predetermined flow rate of oxidizing gas are branched to the oxidizing gas supply branch pipe and supplied to a plurality of SOFC cartridges 203. The oxidizing gas supply chamber 221 is an area surrounded by the lower casing 229b, the lower tube plate 225b, and the lower heat insulator 227b of the SOFC cartridge 203, and is formed by an oxidizing gas supply hole 233a provided on the side surface of the lower casing 229b. , Communicated with an oxidizing gas supply branch pipe (not shown). The oxidizing gas supply chamber 221 is configured to supply a predetermined flow rate of oxidizing gas supplied from an oxidizing gas supply branch pipe (not shown) through the oxidizing gas supply hole 233a to the power generation chamber 215 through the oxidizing gas supply gap 235a. Can be guided at a substantially uniform flow rate.

  The oxidizing gas discharge chamber 223 is a region surrounded by the upper casing 229a, the upper tube plate 225a, and the upper heat insulator 227a of the SOFC cartridge 203, and is formed by an oxidizing gas discharge hole 233b provided on the side surface of the upper casing 229a. , Communicated with an oxidizing gas discharge branch pipe (not shown). The oxidizing gas discharge chamber 223 converts exhaust air supplied from the power generation chamber 215 through the oxidizing gas discharge gap 235b to the oxidizing gas discharge chamber 223 through an oxidizing gas discharge hole 233b. It can lead to a gas discharge branch.

  The upper tube plate 225a is arranged between the top plate of the upper casing 229a and the upper heat insulator 227a so that the upper tube plate 225a, the top plate of the upper casing 229a and the upper heat insulator 227a are substantially parallel to each other. It is fixed to the side plate. The upper tube sheet 225a has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203, and the cell stacks 101 are inserted into the holes, respectively. The upper tube sheet 225a hermetically supports one end of the plurality of cell stacks 101 via one or both of a sealing member and an adhesive member, and also includes a fuel raw material gas supply chamber 217 and an oxidizing gas discharge chamber. 223 is isolated.

  The lower tube plate 225b is disposed on the side plate of the lower casing 229b so that the lower tube plate 225b, the bottom plate of the lower casing 229b, and the lower heat insulator 227b are substantially parallel between the bottom plate of the lower casing 229b and the lower heat insulator 227b. It is fixed. The lower tube sheet 225b has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203, and the cell stacks 101 are inserted into the holes, respectively. The lower tube sheet 225b hermetically supports the other end of the plurality of cell stacks 101 via one or both of a sealing member and an adhesive member, and also includes a fuel source gas discharge chamber 219 and an oxidizing gas supply chamber. 221 is isolated.

  The upper heat insulator 227a is disposed at the lower end of the upper casing 229a so that the upper heat insulator 227a, the top plate of the upper casing 229a and the upper tube plate 225a are substantially parallel to each other, and is fixed to the side plate of the upper casing 229a. Yes. Further, the upper heat insulator 227a is provided with a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203. The diameter of the hole is set larger than the outer diameter of the cell stack 101. The upper heat insulator 227a includes an oxidizing gas discharge gap 235b formed between the inner surface of this hole and the outer surface of the cell stack 101 inserted through the upper heat insulator 227a.

  The upper heat insulator 227a separates the power generation chamber 215 and the oxidizing gas discharge chamber 223, and the atmosphere around the upper tube sheet 225a is heated to reduce the strength and the corrosion caused by the oxidizing agent contained in the oxidizing gas. Suppresses the increase. The upper tube sheet 225a and the like are made of a metal material having high temperature durability such as Inconel, but the upper tube sheet 225a and the like are exposed to the high temperature in the power generation chamber 215, and the temperature difference in the upper tube sheet 225a and the like becomes large. This prevents thermal deformation. The upper heat insulator 227a guides the exhaust oxidizing gas exposed to a high temperature through the power generation chamber 215 to the oxidizing gas exhaust chamber 223 through the oxidizing gas discharge gap 235b.

  According to this embodiment, due to the structure of the SOFC cartridge 203 described above, the fuel raw material gas and the oxidizing gas flow oppositely on the inner side and the outer side of the cell stack 101. As a result, the exhaust oxidizing gas exchanges heat with the fuel raw material gas supplied to the power generation chamber 215 through the inside of the base tube 103, and the upper tube plate 225a made of a metal material is buckled. Then, it is cooled to a temperature at which it is not deformed and supplied to the oxidizing gas discharge chamber 223. The fuel raw material gas is heated by heat exchange with the exhaust oxidizing gas discharged from the power generation chamber 215 and supplied to the power generation chamber 215. As a result, the fuel source gas preheated to a temperature suitable for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

  The lower heat insulator 227b is disposed at the upper end of the lower casing 229b so that the lower heat insulator 227b, the bottom plate of the lower casing 229b, and the lower tube plate 225b are substantially parallel to each other, and is fixed to the side plate of the lower casing 229b. . Also, the lower heat insulator 227b is provided with a plurality of holes corresponding to the number of cell stacks 101 provided in the SOFC cartridge 203. The diameter of the hole is set larger than the outer diameter of the cell stack 101. The lower heat insulator 227b includes an oxidizing gas supply gap 235a formed between the inner surface of this hole and the outer surface of the cell stack 101 inserted through the lower heat insulator 227b.

  The lower heat insulator 227b separates the power generation chamber 215 and the oxidizing gas supply chamber 221, and the atmosphere around the lower tube sheet 225b is heated to lower the strength and corrode by the oxidizing agent contained in the oxidizing gas. Suppresses the increase. The lower tube sheet 225b and the like are made of a metal material having a high temperature durability such as Inconel. It is something to prevent. The lower heat insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply chamber 221 to the power generation chamber 215 through the oxidizing gas supply gap 235a.

  According to this embodiment, due to the structure of the SOFC cartridge 203 described above, the fuel raw material gas and the oxidizing gas flow oppositely on the inner side and the outer side of the cell stack 101. As a result, the exhaust fuel source gas that has passed through the power generation chamber 215 through the interior of the base tube 103 is heat-exchanged with the oxidizing gas supplied to the power generation chamber 215, and the lower tube plate made of a metal material. 225b and the like are cooled to a temperature that does not cause deformation such as buckling and supplied to the fuel raw material gas discharge chamber 219. The oxidizing gas is heated by heat exchange with the exhaust fuel raw material gas and supplied to the power generation chamber 215. As a result, the oxidizing gas heated to the temperature necessary for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

  The direct-current power generated in the power generation chamber 215 is led out to the vicinity of the end of the cell stack 101 by the lead film 115 made of Ni / YSZ or the like provided in the plurality of fuel cells 105, and then the current collector rod (non-current) of the SOFC cartridge 203 The current is collected via a current collecting plate (not shown) to the outside of each SOFC cartridge 203. The direct-current power led out of the SOFC cartridge 203 by the current collector rod is connected to the predetermined series number and parallel number of the generated power of each SOFC cartridge 203, and is led out of the SOFC module 201. The power is converted into predetermined AC power by a power converter (an inverter or the like) such as a power conditioner (not shown) and supplied to a power supply destination (for example, a load facility or a power system).

As described above, the combined power generation system control device, the combined power generation system, the combined power generation system control method, and the combined power generation system control program according to the present embodiment have the following operational effects.
According to this configuration, when the combined power generation system 1 including the SOFC 10 using the biogas 20 as a fuel raw material gas is started, the city gas is supplied to the combustor 81 of the gas turbine 80 at the time (t1) that is the start process of the gas turbine 80. By supplying only 30, since the methane concentration fluctuates and the biogas 20 whose combustion speed is slower than that of the city gas 30 is not used, the gas turbine 80 can be stably started, and the flame of the gas turbine 80 is stabilized. Misfire of the gas turbine 80 can be prevented.

In addition, since the supply start time (t2) of the biogas 20 is determined according to the power generation chamber temperature T1 of the SOFC 10 and the temperature increase rate per unit time thereof, appropriate supply in a state where the combustion of the gas turbine 80 is stable. The supply of the biogas 20 can be started at time (t2) which is a timing. In addition, the supply of the city gas 30 can be stopped while the combustion of the gas turbine 80 is stable, and the supply flow rate of the city gas 30 can be reduced and minimized, so that the city gas consumption can be reduced. Moreover, since the gas turbine 80 can be started appropriately and the gas turbine 80 can be started quickly, the SOFC 10 can be started quickly.
In addition, since a gas turbine biogas supply line 307 for supplying the biogas 20 to the combustor 81 of the gas turbine 80 and a city gas supply line 308 for the gas turbine for supplying the city gas 30 are provided, the biogas whose methane concentration varies. Without adjusting the concentration of 20 methane gas components and adjusting the supply flow rate of the biogas 20 according to the methane concentration, the supply flow rate of the city gas 30 corresponding to the case where the methane concentration of the biogas 20 fluctuates and decreases is adjusted. Thus, the methane concentration can be easily within the predetermined concentration range.

Further, according to the present embodiment, the fuel supplied to the combustor 81 of the gas turbine 80 so that the methane concentration of the fuel raw material gas supplied to the combustor 81 of the gas turbine 80 falls within a predetermined concentration range of 60% by volume or more. Since each supply flow rate of the biogas 20 and the city gas 30 as the raw material gas is adjusted, it is not necessary to concentrate the methane gas component of the biogas 20 whose methane concentration varies. Therefore, the cost required for concentration of methane gas components can be reduced.
Further, for example, when the supply flow rate is adjusted according to the methane concentration of the biogas 20 supplied to the combustor 81 of the gas turbine 80, the biogas 20 has a slow combustion speed, so that the flame does not stabilize and misfires. It is difficult to start up the turbine 80. However, according to this configuration, the supply flow rate of the city gas 30 is adjusted to cope with the change in the methane concentration of the biogas 20, and the combustion of the combustor 81 is stabilized by keeping the methane concentration within a predetermined range, thereby stabilizing the gas turbine 80. Can be started.

  Further, according to the present embodiment, when the power generation chamber temperature T1 exceeds the first threshold value, the supply of the biogas 20 to the fuel electrode 109 of the SOFC 10 is started at time (t3). Supply of the fuel raw material gas to the SOFC 10 can be started after the chamber temperature T1 rises to a predetermined temperature and the operation of the gas turbine 80 is stabilized.

  Further, according to the present embodiment, when the power generation chamber temperature T1 rises and exceeds the second threshold value, the supply of the biogas 20 to the air electrode 113 of the SOFC 10 is started at time (t4). After the start of the supply of the biogas 20, the power generation chamber temperature T1 can be further increased by stably performing catalytic combustion on the air electrode 113 side of the SOFC 10.

  In addition, according to the present embodiment, if the methane concentration of the biogas 20 is 60% by volume or more, catalytic combustion at the air electrode 113 of the SOFC 10 can be performed more stably, so the supply of the biogas 20 to the air electrode 113 is possible. Is started at a value smaller than the second threshold, that is, the supply of the biogas 20 to the air electrode 113 can be accelerated, so that the activation of the SOFC 10 can be accelerated.

  In addition, according to the present embodiment, when the initial fuel of the air electrode 113 is not stable, the supply of the city gas 30 is started before the supply of the biogas 20 is started when the power generation chamber temperature T1 exceeds the second threshold value. , Catalytic combustion is stabilized.

  In addition, according to the present embodiment, when an abnormality occurs in the supply of the biogas 20, such as when the supply of the biogas 20 decreases, stops, or the methane concentration in the biogas 20 decreases, the supply flow rate of the city gas 30 As a result, the city gas 30 can be used as a reserve system for the biogas 20. Thereby, the combined power generation system 1 can be operated more stably. When the operation with the biogas 20 is difficult due to the stop or decrease of the supply of the biogas 20, it is possible to continue the operation by switching the system from the biogas 20 to the city gas 30. Can be improved.

  As mentioned above, although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the gist of the present invention. .

For example, in each of the above-described embodiments, the city gas is used as the predetermined fuel gas. However, another gas whose calorific value is previously adjusted to be substantially constant may be used, such as LPG.
The control device of each embodiment described above may be applied to a triple combined cycle (registered trademark) in which an SOFC, a gas turbine, and a steam turbine are combined.

1 Combined power generation system 10 SOFC (solid oxide fuel cell, fuel cell)
11 Power generation chamber temperature sensor 14 Combustor inlet temperature sensor 20 Biogas (methane concentration variation gas)
21 Density meter 30 City gas (predetermined fuel gas)
40 Water 70 Control device 80 MGT (gas turbine)
81 Combustor 83 Turbine 84 Compressor 85 Regenerative heat exchanger 86 Generator 90 Chimney 109 Fuel electrode 113 Air electrode 215 Power generation chamber 301 Fuel electrode fuel raw material gas supply line 302 Air electrode fuel raw material gas supply line 303 Fuel electrode fuel raw material gas discharge Line 304 Recirculation line 305 Oxidizing gas discharge line 306 Air cathode oxidizing gas supply line 307 Biogas supply line for gas turbine (methane concentration fluctuation gas supply line for gas turbine)
308 City gas supply line for gas turbine (predetermined fuel gas supply line for gas turbine)
309 Gas turbine fuel feed gas supply line 310 Biogas supply line (methane concentration fluctuation gas supply line)
311 City gas supply line (specified fuel gas supply line)
312 Fuel cell bypass line 313 Heat exchanger bypass line 314 Water supply line for reforming

Claims (11)

A fuel cell comprising a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring the temperature of the power generation chamber, and using a methane concentration fluctuation gas whose methane concentration fluctuates during operation as a fuel raw material gas;
A gas turbine that is operated using exhaust fuel source gas discharged from the fuel cell;
A densitometer for measuring the methane concentration in the methane concentration variable gas;
A control device for a combined power generation system comprising:
A gas turbine methane concentration variation gas supply line for supplying the methane concentration variation gas to the gas turbine and a gas turbine predetermined fuel gas supply line for supplying a predetermined fuel gas;
In the starting process of the gas turbine, the supply of the predetermined fuel gas to the gas turbine is started at the same time as starting, and according to the temperature increase rate per unit time of the power generation chamber temperature measured by the power generation chamber temperature sensor and the methane concentration And determining the supply start time, supply flow rate, and supply flow rate of the predetermined fuel gas supplied to the gas turbine, and switching the fuel of the gas turbine from the predetermined fuel gas to the methane concentration change gas. Control device for combined power generation system.   The methane concentration variation gas, which is the fuel raw material gas supplied to the gas turbine, and the predetermined amount so that the methane concentration of the fuel raw material gas supplied to the gas turbine is in a predetermined concentration range of 60% by volume or more. The combined power generation system control device according to claim 1, wherein each supply flow rate of the fuel gas is adjusted.   3. The combined power generation according to claim 1, wherein after the gas turbine is started, when the temperature of the power generation chamber exceeds a first threshold, the supply of the methane concentration varying gas to the fuel electrode of the fuel cell is started. System control unit.   The control apparatus of the combined power generation system according to claim 3, wherein when the temperature of the power generation chamber exceeds a second threshold value that is larger than the first threshold value, supply of the methane concentration varying gas to the air electrode of the fuel cell is started.   When the methane concentration of the methane concentration fluctuation gas is 60% by volume or more, the supply of the methane concentration fluctuation gas to the air electrode of the fuel cell is started at a value smaller than the second threshold and larger than the first threshold. The control apparatus of the combined power generation system according to claim 4.   The supply of the predetermined fuel gas is started before the supply of the methane concentration variation gas is started when the power generation chamber temperature exceeds the second threshold when the initial combustion of the air electrode is not stable. Control device for combined power generation system.   The control apparatus for a combined power generation system according to any one of claims 1 to 6, wherein the fuel cell is a solid oxide fuel cell.   The control apparatus of the combined power generation system according to any one of claims 1 to 7, wherein when an abnormality occurs in the supply of the methane concentration fluctuation gas, the supply flow rate of the predetermined fuel gas is increased. A fuel cell comprising a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring the temperature of the power generation chamber, and using a methane concentration fluctuation gas whose methane concentration fluctuates during operation as a fuel raw material gas;
A gas turbine that is operated using exhaust fuel source gas discharged from the fuel cell;
A gas turbine methane concentration variation gas supply line for supplying the gas turbine with the methane concentration variation gas;
A predetermined fuel gas supply line for a gas turbine for supplying a predetermined fuel gas to the gas turbine;
A combined power generation system comprising the control device according to any one of claims 1 to 8. A fuel cell comprising a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring the temperature of the power generation chamber, and using a methane concentration variation gas whose methane concentration varies during operation as a fuel raw material gas;
A gas turbine that is operated using exhaust fuel source gas discharged from the fuel cell;
A densitometer for measuring the methane concentration in the methane concentration variable gas;
A method for controlling a combined power generation system comprising:
A gas turbine methane concentration variation gas supply line for supplying the methane concentration variation gas to the gas turbine and a gas turbine predetermined fuel gas supply line for supplying a predetermined fuel gas;
In the starting process of the gas turbine, supply of the predetermined fuel gas is started at the time of starting, and the gas turbine is supplied to the gas turbine according to the temperature increase rate per unit time of the power generation chamber temperature measured by the power generation chamber temperature sensor and the methane concentration. A control method for a combined power generation system, wherein a supply start time, a supply flow rate, and a supply flow rate of the predetermined fuel gas are determined for the supplied methane concentration fluctuation gas. A fuel cell comprising a fuel electrode, an air electrode, and a power generation chamber temperature sensor for measuring the temperature of the power generation chamber, and using a methane concentration variation gas whose methane concentration varies during operation as a fuel raw material gas;
A gas turbine that is operated using exhaust fuel source gas discharged from the fuel cell;
A densitometer for measuring the methane concentration in the methane concentration variable gas;
A control program for a combined power generation system comprising:
A gas turbine methane concentration variation gas supply line for supplying the methane concentration variation gas to the gas turbine and a gas turbine predetermined fuel gas supply line for supplying a predetermined fuel gas;
In the gas turbine start-up process, the predetermined fuel gas supply command is started together with the start-up, and the gas according to the temperature increase rate per unit time of the power generation chamber temperature measured by the power generation chamber temperature sensor and the methane concentration A control program for a combined power generation system that determines a supply start time, a supply flow rate, and a supply flow rate of the predetermined fuel gas for the methane concentration variation gas supplied to a turbine.

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