JP6719915B2 - Fuel cell-hydrogen production system and operating method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel cell-hydrogen production system and an operating method thereof.

2. Description of the Related Art There is known a fuel cell that generates electric power by chemically reacting a fuel gas and oxygen. Among them, in solid oxide fuel cells (Solid Oxide Fuel Cell, hereinafter referred to as “SOFC”), ceramics such as zirconia ceramics are used as an electrolyte. For example, hydrogen (H ₂ ) and carbon monoxide (CO), A fuel cell that operates with hydrocarbon-based gases such as methane (CH ₄ ), city gas and natural gas, as well as gas produced from carbonaceous raw materials such as petroleum, methanol and coal gasification gas using gasification equipment. is there.

This fuel cell includes not only power generation but also a system for producing hydrogen from off-gas of the fuel cell, and a hydrogen production system using exhaust heat of the fuel cell. Patent Document 1 discloses a method for producing high-purity hydrogen by transforming off-gas of a solid oxide fuel cell (SOFC) with a CO shift converter. Patent Document 2 describes that internal reforming of SOFC is used to purify anode off-gas from SOFC to produce hydrogen.

JP, 2002-334714, A (claim 1). JP 2009-179541 A (paragraph [0002])

In the hydrogen production system using the internal reforming of SOFC, it is necessary to reduce the one-pass fuel utilization rate in order to increase the production amount of hydrogen. Here, the one-pass fuel utilization rate is the ratio of the fuel used for power generation to the total fuel supplied to the fuel electrode, and is supplied to the fuel electrode when there is recirculation of exhaust fuel gas on the fuel electrode side in the SOFC power generation system. The total fuel included in the evaluation includes the fuel in the recirculated gas. For example, in order to reduce the one-pass fuel utilization rate, the supply amount of fuel gas is increased with respect to the generated current.

However, when the supply amount of the fuel gas increases, the amount of hydrocarbon gas such as methane (CH ₄ ) increases, and the amount of heat absorption increases due to an increase in the internal reforming reaction amount, resulting in a decrease in the SOFC temperature. On the other hand, in the SOFC, when the fuel gas flow rate is kept constant and the power generation output is reduced, the amount of heat generated by the power generation reaction decreases. The amount of hydrogen produced increases the fuel gas supply while maintaining the power generation output. If the heat balance between reforming and power generation is lost and the optimum temperature for power generation cannot be maintained, the internal resistance of the SOFC The power generation performance is significantly reduced due to the increase of Therefore, in a hydrogen production system using SOFC that performs internal reforming, a temperature change of the SOFC occurs when continuously switching from a power generation operation of only power generation to a hydrogen production operation of combined use of power generation and hydrogen production. However, there is a problem that the power generation output cannot be maintained and it may not be possible to easily switch to the hydrogen production operation.

The present invention has been made in view of such circumstances, and an object thereof is to provide a fuel cell-hydrogen production system capable of continuously switching between a power generation operation and a hydrogen production operation.

The present invention relates to a power generation section having a cell for generating power by a reaction between a fuel gas and an oxidizing gas, a fuel gas supply section for supplying the fuel gas to the power generation section, and a supply of the oxidizing gas to the power generation section. An oxidizing gas supply unit, a steam supply unit that supplies steam to the fuel gas supply unit, and a temperature measurement unit that measures the temperature of the fuel gas inlet-side power generation unit that is installed on the fuel gas inlet side of the power generation unit. A temperature control unit for controlling the temperature of the fuel gas inlet side power generation unit, an operation mode control unit for increasing the flow rate of the fuel gas in response to a hydrogen production command, and the exhaust gas discharged from the power generation unit. comprising a recirculation unit recirculating at least a portion of the fuel gas to the fuel gas supply unit, wherein the temperature control unit, the exhaust in response to the temperature of said fuel gas inlet-side power generation section measured by the temperature measuring unit a recirculation control unit for controlling the recirculation flow rate of the fuel gas including the fuel cell - to provide a hydrogen production system.

The operation mode control unit makes it possible to supply hydrogen while maintaining the power generation output of the SOFC by increasing the fuel gas flow rate during the hydrogen production mode operation as compared to during the power generation mode operation. That is, the amount of hydrogen produced can be increased. Further, even during the hydrogen production mode operation, fuel gas is supplied to the power generation unit to generate power. Here, the power generation section is a section in the axial direction of the cell stack where there are a plurality of fuel cell groups electrically connected by an interconnector.

By providing the temperature measurement unit and the temperature control unit, the power generation unit can be maintained at a temperature suitable for power generation even if the reforming endothermic amount during hydrogen generation increases or the heat generation amount due to power generation decreases.

The exhaust fuel gas contains unreformed hydrocarbon and the like. Therefore, the amount of hydrocarbons supplied to the fuel cells can be adjusted by controlling the recirculation flow rate of the exhaust fuel gas to the fuel gas. As a result, the amount of heat absorbed by the fuel cells is adjusted, so that the power generation section can be maintained at a temperature suitable for power generation.

The water vapor supplied to the fuel gas supply unit is mixed with the fuel gas. The fuel gas contains hydrocarbons. By mixing water vapor with the fuel gas, the proportion of hydrocarbons in the fuel gas can be reduced. As a result, the reforming endothermic amount in the fuel cell unit is adjusted, so that the power generation unit can be maintained at a temperature suitable for power generation.

Oite above onset Ming, before Symbol recirculation control unit, when the temperature of the fuel gas inlet-side power generation part is a predetermined temperature or less, the set flow rate component of the recirculation flow of the exhaust fuel gas, a function of reducing I have it.

By setting the recirculation flow rate to be reduced in advance and reducing the set flow rate, the flow rate of the recirculation gas having a relatively low temperature with respect to the power generation unit is reduced and the cooling effect is suppressed and the recirculation is performed. By reducing the flow rate of hydrocarbons such as methane (CH ₄ ) supplied from gas, the heat absorption due to internal reforming in the power generation section is reduced, so that the heat balance of the power generation section can be adjusted easily.

Further, the present invention provides a power generation unit having a cell that generates power by a reaction between a fuel gas and an oxidizing gas, a fuel gas supply unit that supplies the fuel gas to the power generation unit, and the oxidizing gas to the power generation unit. A temperature for measuring the temperature of an oxidizing gas supply unit to supply, a steam supply unit to supply steam to the fuel gas supply unit, and a fuel gas inlet side power generation unit installed on the fuel gas inlet side of the power generation unit. The temperature control unit includes a measurement unit, a temperature control unit that controls the temperature of the fuel gas inlet side power generation unit, and an operation mode control unit that receives a hydrogen production command and increases the flow rate of the fuel gas. but includes a steam control unit for controlling the flow rate of the steam in accordance with the temperature of the fuel gas inlet-side power generation section measured by the temperature measuring unit, before Symbol steam control unit, the temperature of the fuel gas inlet-side power generation unit Is a predetermined temperature or less, a fuel cell-hydrogen production system having a function of increasing the steam flow rate by a set flow rate is provided .

By setting the steam flow rate to be increased in advance and increasing the set flow rate, the concentration of hydrocarbon gas such as methane (CH ₄ ) at the fuel electrode outlet of the power generation section is reduced. This reduces the flow rate of hydrocarbons such as methane (CH ₄ ) supplied to the recirculation gas that is branched from the exhaust fuel gas and recirculated, thereby reducing the heat absorption due to internal reforming in the power generation unit. It becomes easy to adjust the heat balance of the part.

Further, the present invention provides a power generation unit having a cell that generates power by a reaction between a fuel gas and an oxidizing gas, a fuel gas supply unit that supplies the fuel gas to the power generation unit, and the oxidizing gas to the power generation unit. A temperature for measuring the temperature of an oxidizing gas supply unit to supply, a steam supply unit to supply steam to the fuel gas supply unit, and a fuel gas inlet side power generation unit installed on the fuel gas inlet side of the power generation unit. A measurement unit, a temperature control unit that controls the temperature of the fuel gas inlet side power generation unit, an operation mode control unit that increases the flow rate of the fuel gas in response to a hydrogen production command, and a temperature control unit that is discharged from the power generation unit. A recirculation unit for recirculating at least a part of the exhaust fuel gas to the fuel gas supply unit,
And a temperature control unit for controlling the recirculation flow rate of the exhaust fuel gas according to the temperature of the fuel gas inlet side power generation unit measured by the temperature measurement unit, and the temperature measurement unit. in comprises a steam controller for controlling the flow rate of the steam in accordance with the temperature of the fuel gas inlet-side power generation unit measured, before Symbol recirculation control unit, the temperature of the fuel gas inlet-side power generation unit is the first predetermined temperature In the case of the following, it has a function of reducing the recirculation flow rate of the exhaust fuel gas by a set flow rate, and the water vapor control section is configured to operate when the temperature of the fuel gas inlet side power generation section is equal to or lower than a second predetermined temperature. A fuel cell-hydrogen production system having a function of increasing the steam flow rate by a set flow rate, wherein the first predetermined temperature is different from the second predetermined temperature.

By setting the first predetermined temperature to be different from the second predetermined temperature, the timing at which the temperature control by the recirculation control unit is performed can be shifted from the temperature control by the water vapor control unit. As a result, the control factor for reducing the concentration of hydrocarbon gas such as methane (CH ₄ ) at the inlet of the power generation section is clarified, and the control for reducing the heat absorption due to internal reforming in the power generation section is facilitated. It is easy to adjust the balance.

In one aspect of the above invention, it is preferable that the first predetermined temperature is higher than the second predetermined temperature.

Thereby, the temperature control by the recirculation control unit is preferentially performed. Generation of water vapor requires energy, and it is not preferable because it enlarges the generation source of water vapor and hinders the reaction of the fuel cell, and it is preferable that the temperature can be controlled without additionally using water vapor. By prioritizing the temperature control by the recirculation control unit, it is possible to efficiently control the temperature of the power generation unit.

In one aspect of the above invention, the temperature control unit stops increasing the fuel gas flow rate when the temperature of the fuel gas inlet side power generation unit measured by the temperature measurement unit is equal to or lower than a third predetermined temperature. The third predetermined temperature may be lower than the first predetermined temperature and the second predetermined temperature.

By stopping the increase in the fuel gas flow rate, it is possible to suppress the increase in the amount of hydrocarbons supplied to the power generation unit. As a result, the flow rate of hydrocarbon gas such as methane (CH ₄ ) in the fuel gas is reduced, thereby reducing the endothermic heat due to internal reforming in the power generation unit, thus suppressing an increase in the reforming endothermic amount and reducing the power generation unit. It is possible to suppress the temperature decrease.

In one aspect of the above invention, the fuel control unit has a function of reducing the fuel gas flow rate by a set flow rate when the temperature of the fuel gas inlet side power generation section is equal to or lower than a fourth predetermined temperature, It is preferable that the fourth predetermined temperature is lower than the third predetermined temperature.

By reducing the fuel gas flow rate, it is possible to further reduce the reforming endothermic amount and suppress the temperature decrease of the power generation unit. Further, by reducing the fuel gas flow rate as the final control determination, the SOFC power generation amount can be maintained until the final control determination.

In one aspect of the above invention, the fuel control unit includes a warning unit that issues a warning, and the fuel control unit issues a warning when the temperature of the fuel gas inlet side power generation unit is equal to or lower than the fourth predetermined temperature, and the fuel gas inlet. It is preferable to have a function of controlling the warning unit so as to cancel the warning when the temperature of the side power generation unit exceeds the third predetermined temperature.

When the warning unit issues a warning, the user can be made aware of the required degree of temperature control.

Further, the present invention provides a step of supplying hydrocarbon and water vapor to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide, and a step of oxidizing the fuel gas containing the hydrogen and the carbon monoxide and oxidizing the power generation section. A step of supplying a reactive gas to generate electric power, a step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section, and a temperature of the fuel gas inlet side power generating section A step of controlling, a step of increasing the flow rate of the fuel gas in response to a command for hydrogen production, and a step of recirculating at least a part of the exhaust fuel gas discharged from the power generation section to the upstream side of the power generation section. If, comprising a step of controlling the temperature of said fuel gas inlet-side power generation unit, including the control process a for controlling the recirculation flow of the exhaust fuel gas in accordance with the measured temperature of the fuel gas inlet-side power generation unit fuel cell - provides a method for operating a hydrogen production system.

Oite above onset bright, the pre-SL control process A, wherein when the temperature of the fuel gas inlet-side power generation part is a predetermined temperature or less, the set flow rate component of the recirculation flow of the exhaust fuel gas reduces.

Further, the present invention provides a step of supplying hydrocarbon and water vapor to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide, and a step of oxidizing the fuel gas containing the hydrogen and the carbon monoxide and oxidizing the power generation section. A step of supplying a reactive gas to generate electric power, a step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section, and a temperature of the fuel gas inlet side power generating section A step of controlling, and a step of increasing the flow rate of the fuel gas in response to a hydrogen production command, and a step of controlling the temperature of the fuel gas inlet side power generation section, includes a control step B for controlling the flow rate of the steam in accordance with the measured temperature, the pre-Symbol controlling step B, when the temperature of the fuel gas inlet-side power generation part is a predetermined temperature or lower, set flow rate component of the steam flow rate , And a method of operating a fuel cell-hydrogen production system for increasing the number of fuel cells .

Further, the present invention provides a step of supplying hydrocarbon and water vapor to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide, and a step of oxidizing the fuel gas containing the hydrogen and the carbon monoxide and oxidizing the power generation section. A step of supplying a reactive gas to generate electric power, a step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section, and a temperature of the fuel gas inlet side power generating section A step of controlling, a step of increasing the flow rate of the fuel gas in response to a command for hydrogen production, and a step of recirculating at least a part of the exhaust fuel gas discharged from the power generation section to the upstream side of the power generation section. And a control step A of controlling the temperature of the fuel gas inlet side power generation section, the step of controlling the recirculation flow rate of the exhaust fuel gas according to the measured temperature of the fuel gas inlet side power generation section, and It includes a control step B for controlling the flow rate of the water vapor according to the measured temperature of the fuel gas inlet side power generation unit, and sets a first predetermined temperature and a second predetermined temperature that is a temperature different from the first predetermined temperature. In the control step A, when the temperature of the fuel gas inlet side power generation section is equal to or lower than the first predetermined temperature, the recirculation flow rate of the exhaust fuel gas is reduced by a set flow rate, and in the control step B, Provided is a method of operating a fuel cell-hydrogen production system , which increases the steam flow rate by a set flow rate when the temperature of the fuel gas inlet side power generation section is equal to or lower than the second predetermined temperature.

In one aspect of the above invention, it is preferable that the first predetermined temperature is higher than the second predetermined temperature.

In one aspect of the above invention, a third predetermined temperature that is lower than the first predetermined temperature and the second predetermined temperature is set, and the measured temperature of the fuel gas inlet side power generation unit is equal to or lower than the third predetermined temperature. In some cases, a step of controlling to stop the increase of the fuel gas flow rate may be included.

In one aspect of the above invention, when a fourth predetermined temperature that is lower than the third predetermined temperature is set and the measured temperature of the fuel gas inlet side power generation unit is equal to or lower than the fourth predetermined temperature, the fuel gas It is advisable to reduce the flow rate by the set flow rate.

In an aspect of the above invention, a warning is issued when the measured temperature of the fuel gas inlet side power generation section is equal to or lower than the fourth predetermined temperature, and the temperature of the fuel gas inlet side power generation section exceeds the third predetermined temperature. The warning should be canceled.

According to the present invention, since the temperature of the power generation unit can be maintained in the hydrogen production mode, continuous switching from the power generation mode to the hydrogen production mode is possible.

1 is a block diagram of a combined power generation system to which a fuel cell-hydrogen production system according to an embodiment of the present invention is applied. It is a perspective view showing the outline of the SOFC module concerning one embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of the SOFC cartridge according to the embodiment of the present invention. It is a fragmentary sectional view of the cell stack concerning one embodiment of the present invention. 5 is a graph illustrating a change in the temperature distribution of the SOFC cartridge due to an operation change from the power generation mode to the hydrogen production mode of the fuel cell-hydrogen production system. 6 is a graph illustrating the concept of changes in the gas composition distribution of the SOFC cartridge due to operation changes from the power generation mode of the fuel cell-hydrogen production system to the hydrogen production mode. It is a flow figure showing an example of temperature control of the power generation part at the time of hydrogen production mode operation. It is a graph explaining the operating conditions in the hydrogen production mode of the fuel cell-hydrogen production system.

In the following, for convenience of description, the positional relationship between the respective constituent elements is specified using the expressions “upper” and “lower” with reference to the paper surface, but this need not always be the case with respect to the vertical direction. For example, the upward direction on the paper surface may correspond to the downward direction on the vertical direction. Further, the vertical direction on the paper surface may correspond to the horizontal direction perpendicular to the vertical direction.

Further, in the following, a cylindrical type is described as an example of a cell stack of a solid oxide fuel cell (SOFC), but the cell stack is not necessarily limited to this, and may be a flat cell stack, for example.

Hereinafter, an embodiment of a fuel cell-hydrogen production system of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a combined power generation system to which a fuel cell-hydrogen production system according to this embodiment is applied.

The combined cycle power generation system 1 includes a fuel cell-hydrogen production system 2, a gas turbine system 3 that uses the gas discharged from the fuel cell-hydrogen production system 2 to generate electric power, and exhaust gas from the gas turbine system 3. And an exhaust heat recovery unit 4 for recovering the heat of.

The fuel cell-hydrogen production system 2 includes a solid oxide fuel cell (SOFC) module 201 having a power generation unit.
Here, the power generation unit 108 is a portion having a plurality of fuel cell groups electrically connected by an interconnector in the axial direction of the cell stack.
Further, the fuel cell-hydrogen production system 2 includes a fuel gas supply unit (11a, 11b) that supplies a fuel gas to the power generation unit 108, an oxidizing gas supply path 12 that supplies an oxidizing gas to the power generation unit 108, and a power generation unit. Exhaust fuel gas path 13 for discharging the fuel gas (exhaust fuel gas) from the SOFC module 201 through 108, and exhaust oxidizing gas path for discharging the oxidizing gas (exhaust oxidizing gas) from the SOFC 201 through the power generation unit 108 14, a recirculation unit (15a, 15b) for recirculating exhaust fuel gas to the fuel gas supply unit (11a, 11b), and a steam supply unit (16a, 16a, for supplying steam to the fuel gas supply unit (11a, 11b). 16b), the control device 17, and the temperature measuring unit 28 (see FIG. 3) that measures the temperature of the fuel gas inlet-side power generating unit 108a, which is the fuel gas inlet portion of the power generating unit 108.
Here, in the present embodiment, the temperature of the fuel gas inlet side power generation unit 108a is measured. The fuel gas inlet side power generation unit 108a is located in the fuel cell 105 on the fuel gas inlet side of the cell stack 101, and is selected as a region susceptible to temperature change due to internal reforming of methane (CH ₄ ) in the fuel gas. Measure the temperature change. In addition to the fuel gas inlet side of the cell stack 101, the temperature of the region where the temperature of the fuel cell unit 105 is likely to decrease under the influence of temperature change due to internal reforming may be measured.

The fuel cell-hydrogen production system 2 includes a shift reactor 18 that produces hydrogen using exhaust fuel gas from the SOFC module 201, and water that separates water from the exhaust fuel gas that has passed through the shift reactor 18 by heat exchange. A separator 19 and a hydrogen purification device (for example, PSA) 20 that purifies hydrogen from the exhaust fuel gas that has passed through the water separator 19 are provided. The hydrogen (H) purified by the hydrogen purification device 20 can be used for a fuel cell vehicle (FCV) 21 that drives hydrogen as a fuel. The off gas (C) such as CH ₄ separated by the hydrogen purifier 20 is incinerated. The off gas (C) may be used for heat recovery as heat for generating steam in the exhaust heat recovery unit 4.

The gas turbine system 3 sucks in air (A), which is an oxidizing gas for SOFC, pressurizes the sucked air and supplies it to the SOFC module 201, and exhaust fuel gas and fuel from the SOFC module 201. A combustor 32 that combusts (F) to generate high-temperature combustion gas, a micro gas turbine 33 that is driven by the combustion gas, and an air compressor that uses the heat of exhaust combustion gas that is discharged from the micro gas turbine 33. A regenerative heat exchanger 34 for heating the air pressurized by 31 and a generator 35 for generating power by driving the micro gas turbine 33 are provided. The exhaust combustion gas that has passed through the regenerative heat exchanger 34 is supplied to the exhaust heat recovery unit 4.

The exhaust heat recovery unit 4 is a heat exchanger that exchanges heat between the exhaust combustion gas and water (W) to generate steam (S). The steam (S) may be recovered as a heat source and used in the steam supply source 16a or in another device. The exhaust combustion gas (G) that has passed through the exhaust heat recovery unit 4 is appropriately discharged as necessary and then discharged to the atmosphere.

In the fuel cell-hydrogen production system 2, the power generation unit 108 of the SOFC module 201 has a cell (cell stack 101) that receives supply of a fuel gas and an oxidizing gas to generate power by an electrochemical reaction via a solid electrolyte.

The fuel gas supply unit includes a fuel gas supply source 11a and a fuel gas supply path 11b. The fuel gas supply source 11a is connected to the SOFC module 201 via the fuel gas supply path 11b. The fuel gas supplied to the SOFC module 201 generates hydrocarbons (especially methane (CH ₄ )) and water vapor in the vicinity of the fuel electrode 109 of the fuel battery cell 105 of the cell stack 101, especially on the fuel gas inlet side. It undergoes an endothermic reaction and is actively steam-reformed to produce hydrogen and carbon monoxide.

The fuel gas contains a component capable of generating hydrogen by being steam-reformed. For example, a hydrocarbon such as methane (CH ₄ ) is reformed by steam under nickel (Ni) such as a fuel electrode having a catalytic action to become hydrogen (H ₂ ) and carbon monoxide (CO). The fuel gas was produced by a hydrocarbon-based gas such as hydrogen (H ₂ ) and carbon monoxide (CO), methane (CH ₄ ) gas, city gas, natural gas, or a gasification facility for carbonaceous raw materials such as coal. It may be gas or the like.

The oxidizing gas supply path 12 is configured to supply an oxidizing gas (air in this embodiment) to the power generation unit 108 of the SOFC module 201. In FIG. 1, the oxidizing gas supply path 12 is a gas flow path that connects the SOFC module 201 and the gas turbine system 3 so that the compressed air discharged from the gas turbine system 3 can be supplied to the power generation unit 108.

One end of the exhaust fuel gas path 13 is connected to the SOFC module 201 so that the exhaust fuel gas that has passed through the power generation unit 108 can be discharged from the SOFC module 201.

The exhaust oxidizing gas passage 14 has one end connected to the SOFC module 201 and the other end connected to the gas turbine system 3. The exhaust oxidizing gas path 14 can exhaust the exhaust oxidizing gas that has passed through the power generation unit 108 from the SOFC module 201.

The recirculation unit includes a recirculation blower 15a and a recirculation path 15b. The other end of the exhausted fuel gas path 13 is connected to the inlet side of the recirculation blower 15a. The recirculation path 15b has one end connected to the outlet side of the recirculation blower 15a and the other end connected to the fuel gas supply path 11b, and recirculates a part of the exhaust fuel gas to supply it to the fuel gas supply path 11b. There is.

The steam supply section (16a, 16b) includes a steam supply source 16a and a steam supply path 16b. The steam supply source 16a is a boiler or the like that heats water to generate steam. The steam supply path 16b has one end connected to the steam supply source 16a and the other end connected to the recirculation path 15b.

The temperature measuring unit 28 is installed so that the temperature of the fuel cell 105 on the surface of the fuel gas inlet side power generation unit 108a, preferably on the upstream side of the fuel gas flow in the cell stack 101, can be measured. The temperature measuring unit 28 is a measuring device that can measure the temperature of the fuel gas inlet side power generation unit 108a at the operating temperature of the SOFC module 201 and can send the measured temperature information to the control device 17. A thermocouple is mainly used as the temperature measuring unit 28, but a high-temperature non-contact radiation thermometer or the like can also be used.

The control device 17 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into the RAM or the like to execute information processing/arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, provided in a state of being stored in a computer-readable storage medium, or delivered via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

The control device 17 includes a receiving unit 22 that receives a command from the outside, an operation mode control unit 23 that switches operation to a power generation mode or a hydrogen production mode based on the command received by the receiving unit 22, and a temperature measurement that the receiving unit 22 receives. The temperature control unit 24 controls the temperature of the fuel gas inlet side power generation unit 108a based on the temperature information (measured temperature) from the unit 28. The hydrogen production mode is an operation mode in which the amount of hydrogen produced is increased compared to the power generation mode. Even in the hydrogen production mode, fuel gas is supplied to the power generation unit 108 to generate power.

Operation mode control unit 23, when the receiving unit 22 receives a command for power generation, opening the valve V _1, and has a function of controlling so as to close the valve V _2. Operation mode control unit 23, when the receiving unit 22 receives an instruction of hydrogen production, closing the valve V _1, and has a function of controlling so as to open the valve V _2.

The operation mode control unit 23 stores information on the fuel gas flow rate, the exhaust fuel gas recirculation flow rate, and the steam flow rate according to the load current values for the power generation mode and the hydrogen production mode. Each condition of the hydrogen production mode is such that the one-pass fuel utilization rate is 40% to 60%, preferably 45% to 50%, and the S/C (ratio between Steam and Carbon) is 3.0 to 5.0. It is preferably set to 3.5 to 5.0. Here, the one-pass fuel utilization rate is the fuel flow rate at the SOFC fuel electrode inlet and the gas (H ₂ and CO) consumed by the SOFC regardless of whether exhaust fuel gas is recirculated to the fuel electrode side in the SOFC power generation system. The reaction amount is evaluated.

The operation mode control unit 23 appropriately opens and closes the valves V ₃ , V ₄ , and V ₅ based on the command received by the reception unit 22, and sets the fuel gas flow rate, the exhaust fuel gas recirculation flow rate, and the exhaust fuel gas recirculation flow rate to satisfy the conditions for each mode. It has the function of controlling the steam flow rate. When the receiving unit 22 receives a hydrogen production command, the operation mode control unit 23 increases the opening degree of the valve V ₁ to gradually increase the fuel gas flow rate and is capable of producing hydrogen at a predetermined flow rate while generating electricity. To do.

Here, as shown in FIG. 5 and FIG. 6, when the fuel gas flow rate is increased by switching from the power generation mode to the hydrogen production mode, hydrocarbon gas such as methane (CH ₄ ) in the fuel gas increases. As a result, the heat absorption due to internal reforming on the fuel gas inlet side of the cell stack 101 increases, the fuel gas inlet side temperature of the cell stack 101 decreases, and the temperature of the fuel gas inlet side power generation unit 108a (upper cell) reaches a predetermined temperature. There is a case where the temperature distribution of the cell stack 101 is further decreased and the internal resistance of the fuel cell unit 105 is increased, and the power generation performance of the SOFC module 201 is decreased. Therefore, it is effective to suppress the increase of hydrocarbon gas such as methane (CH ₄ ) in the fuel gas on the fuel gas inlet side of the cell stack 101. When the temperature T ₁ of the fuel gas inlet side power generation section 108a in the hydrogen production mode is 700° C. or lower, the resistance increases and the performance decreases.

Further, as shown in FIG. 6, by switching from the power generation mode to the hydrogen production mode, the flow rate of the fuel gas increases, so that a reverse reaction of reforming occurs as an equilibrium reaction of the exhaust fuel gas on the fuel gas outlet side of the cell stack 101. Since the amount of methane (CH ₄ ) generated in the exhaust fuel gas increases, the flow rate of methane (CH ₄ ) in the recirculation gas increases, and as a result, the fuel gas at the fuel gas inlet side of the cell stack 101 increases. It was found that the amount of methane (CH ₄ ) gas therein increased. Therefore, increasing the flow rate of water vapor from the water vapor supply source 16a to control S/C to be large is also effective in suppressing an increase in methane (CH ₄ ) in the exhaust fuel gas.

Therefore, the temperature control unit 24 includes the recirculation control unit 25, the water vapor control unit 26, and the fuel control unit 27, and measures the temperature of the fuel gas inlet side power generation unit 108a when the power generation mode is switched to the hydrogen production mode. Is prevented from falling below a predetermined temperature, thereby suppressing a decrease in power generation performance of the SOFC module 201.

Further, as shown in FIG. 6, the one-pass fuel utilization rate is reduced from, for example, about 55% (X) in the power generation mode to, for example, about 45% (Y) in the hydrogen production mode, thereby producing and supplying hydrogen at a predetermined flow rate. Is possible. Therefore, the temperature control unit 24 reduces the concentration of hydrocarbon gas such as methane (CH ₄ ) in the recirculated gas by calculating the one-pass fuel utilization rate and increasing the one-pass fuel utilization rate. The heat absorption due to the internal reforming on the fuel gas inlet side of the stack 101 is reduced so that the measured temperature of the fuel gas inlet side power generation unit 108a does not drop below a predetermined temperature, so that the power generation performance degradation of the SOFC module 201 can be suppressed.

The recirculation control unit 25 adjusts the opening degree of the valve V ₄ according to the measured temperature of the fuel gas inlet side power generation unit 108a to control the recirculation flow rate of the exhaust fuel gas. When the receiving unit 22 receives the temperature information indicating that the temperature of the fuel gas inlet-side power generation unit 108a is equal to or lower than the first predetermined temperature, the recirculation control unit 25 lowers the opening degree of the valve V ₄ and outputs the exhaust fuel gas. It has the function of reducing the flow rate by the set flow rate.

The set flow rate may be, for example, -1% with respect to the initial recirculation flow rate, and a predetermined flow rate between 0 and -5% of the initial recirculation flow rate may be gradually reduced. The cooling effect is suppressed by reducing the flow rate of the recirculation gas having a relatively low temperature with respect to 108a, and the flow rate of hydrocarbons such as methane (CH ₄ ) supplied from the recirculation gas is reduced to reduce the fuel flow rate. By reducing the concentration of hydrocarbon gas such as methane (CH ₄ ) of the above, the heat absorption due to internal reforming on the fuel gas inlet side of the cell stack 101 is reduced. The reduction limit of the exhaust fuel gas flow rate in the recirculation control unit 25 is preferably -5% with respect to the initial recirculation flow rate. If the set flow rate is lowered below the reduction limit, the amount of vapor supplied to the fuel electrode 109 becomes insufficient, which is not preferable. The initial recirculation flow rate is the recirculation flow rate set as the condition for the hydrogen production mode. After reducing the exhaust fuel gas flow rate to the reduction limit, the control by the recirculation control unit 25 is stopped regardless of the temperature of the fuel gas inlet side power generation unit 108a.

The water vapor control unit 26 controls the water vapor flow rate by adjusting the opening degree of the valve V ₅ according to the measured temperature of the fuel gas inlet side power generation unit 108a. When the receiving unit 22 receives the temperature information that the temperature of the fuel gas inlet-side power generation unit 108a is equal to or lower than the second predetermined temperature, the water vapor control unit 26 increases the opening degree of the valve V ₅ to increase the water vapor supply flow rate. It has the function of increasing the set flow rate. The second predetermined temperature is preferably set to a temperature lower than the first predetermined temperature.

The set flow rate may be, for example, +5% with respect to the initial steam supply flow rate, and a predetermined steam flow rate between 0% and +20% of the initial steam supply flow rate may be increased stepwise. Reduce the concentration of hydrocarbon gases such as methane (CH ₄ ). As a result, the flow rate of hydrocarbons such as methane (CH ₄ ) supplied from the recirculation gas branched from the exhaust fuel gas and recirculated is reduced, and the concentration of hydrocarbons such as methane (CH ₄ ) gas at the fuel inlet is reduced. By doing so, the heat absorption due to internal reforming on the fuel gas inlet side of the cell stack 101 is reduced. The increase limit of the steam supply flow rate in the steam control unit 26 is preferably +20% with respect to the initial steam supply flow rate. When the set flow rate is increased beyond the limit of increase, the system efficiency is lowered because energy is required to generate steam, and the steam supply amount to the fuel electrode 109 is excessively increased to increase the size of the steam supply source 16a. It is not preferable because it hinders the reaction promotion of the battery. The initial steam supply flow rate is the steam supply flow rate set as the condition for the hydrogen production mode. After increasing the steam supply flow rate to the increase limit, the control by the steam control unit 26 is stopped regardless of the temperature of the fuel gas inlet side power generation unit 108a.

The fuel control unit 27 controls the flow rate of the fuel gas by adjusting the opening degree of the valve V ₃ according to the measured temperature of the fuel gas inlet side power generation unit 108a. When the reception unit 22 receives the temperature information that the temperature of the fuel gas inlet side power generation unit 108a is equal to or lower than the third predetermined temperature, the fuel control unit 27 lowers the opening degree of the valve V ₃ to determine the fuel gas flow rate. It has the function of stopping the increase. The third predetermined temperature is set to a temperature lower than the first predetermined temperature and the second predetermined temperature.

When the receiving unit 22 receives the temperature information indicating that the temperature of the fuel gas inlet-side power generation unit 108a is the fourth predetermined temperature or less, the fuel control unit 27 further lowers the opening degree of the valve V ₃ to reduce the fuel gas flow rate. It has a function to reduce the flow rate by the set flow rate. The fourth predetermined temperature is set to a temperature lower than the third predetermined temperature.

The set flow rate may be set to, for example, -1% with respect to the initial fuel gas flow rate, and a predetermined flow rate between 0 and -2% of the initial fuel gas flow rate may be gradually reduced. By reducing the concentration of hydrocarbon gas such as CH ₄ ), the heat absorption due to internal reforming on the fuel gas inlet side of the cell stack 101 is reduced. The reduction limit of the fuel gas flow rate in the fuel control unit 27 is preferably −2% with respect to the initial fuel gas flow rate. If the set flow rate is reduced below the reduction limit, the fuel supply amount to the fuel electrode 109 becomes insufficient, and the power generation amount and the hydrogen production flow amount decrease, which is not preferable. The initial fuel gas flow rate is the fuel gas flow rate set as the condition for the hydrogen production mode. The fuel gas flow rate is gradually increased in the hydrogen production mode. In that case, the fuel gas flow rate immediately before the temperature control in the fuel control unit 27 is started is the initial fuel gas flow rate. After the fuel gas flow rate is reduced to the reduction limit, the control by the fuel control unit 27 is stopped regardless of the temperature of the fuel gas inlet side power generation unit 108a.

It is desirable that the fuel cell-hydrogen production system 2 further includes a warning unit (not shown) that warns the user. The warning unit is an alarm that emits a warning sound, a lamp that displays a warning signal, or the like. The fuel control unit 27 issues a warning when the reception unit 22 receives temperature information that the temperature of the fuel gas inlet side power generation unit 108a is equal to or lower than the fourth predetermined temperature, and then the reception unit 22 causes the fuel gas inlet side. When the temperature information that the temperature of the power generation unit 108a has exceeded the third predetermined temperature is received, it has a function of controlling to cancel the warning.

Temperature control unit 24, in place of the control determination by the temperature of the fuel gas inlet-side power generation unit 108a, calculates the one-pass fuel utilization rate, valve V ₃ to increase the one-pass fuel utilization _rate, V _4, V ₅ appropriately open and close the Then, it may have a function of controlling the fuel gas flow rate, the exhaust fuel gas recirculation flow rate, and the steam flow rate.

By increasing the one-pass fuel utilization rate, the concentration of hydrocarbon gas such as methane (CH ₄ ) in the recirculation gas is reduced, and the heat absorption due to internal reforming at the fuel gas inlet side of the cell stack 101 is reduced. It is possible to suppress a decrease in temperature of the fuel gas inlet side power generation unit 108a.

The temperature control unit 24 may have a function of controlling the temperature measurement unit 28 to intermittently measure the temperature of the fuel gas inlet side power generation unit 108a and transmit the temperature information during the hydrogen production mode operation. By intermittently measuring and transmitting temperature information instead of continuous measurement, the capacity of the control device can be reduced and simplified, and temperature control is stabilized. Considering the rate of temperature change due to the heat capacity, in the case of intermittent measurement and transmission of temperature information, the measurement interval is preferably 30 minutes or more and about 60 minutes.

Next, the SOFC module 201 and the SOFC cartridge 203 according to this embodiment will be described with reference to FIGS. 2 and 3. Here, FIG. 2 shows one mode of the SOFC module 201 according to the present embodiment. Further, FIG. 3 is a cross-sectional view of one aspect of the SOFC cartridge 203 according to the present embodiment.

As shown in FIG. 2, the SOFC module 201 includes, for example, a plurality of SOFC cartridges 203 and a pressure container 205 that houses the plurality of SOFC cartridges 203. Further, the SOFC module 201 has a fuel gas supply pipe 207 and a plurality of fuel gas supply branch pipes 207a. Further, the SOFC module 201 has a fuel gas discharge pipe 209 and a plurality of fuel gas discharge branch pipes 209a. Further, the SOFC module 201 has an oxidizing gas supply pipe (not shown) and an oxidizing gas supply branch pipe (not shown). Further, the SOFC module 201 has an oxidizing gas discharge pipe (not shown) and a plurality of oxidizing gas discharge branch pipes (not shown).

The fuel gas supply pipe 207 is provided outside the pressure vessel 205, is connected to a fuel gas supply unit that supplies a fuel gas of a predetermined gas composition and a predetermined flow rate according to the power generation amount of the SOFC module 201, and also includes a plurality of It is connected to the fuel gas supply branch pipe 207a. The fuel gas supply pipe 207 is for guiding the fuel gas at a predetermined flow rate, which is supplied from the above-mentioned fuel gas supply unit, into a plurality of fuel gas supply branch pipes 207a by branching. The fuel gas supply branch pipe 207 a is connected to the fuel gas supply pipe 207 and also to the plurality of SOFC cartridges 203. The fuel gas supply branch pipe 207a guides the fuel gas supplied from the fuel gas supply pipe 207 to the plurality of SOFC cartridges 203 at substantially equal flow rates, and makes the power generation performances of the plurality of SOFC cartridges 203 substantially uniform. ..

The fuel gas discharge branch pipe 209a is connected to the plurality of SOFC cartridges 203 and is also connected to the fuel gas discharge pipe 209. The fuel gas discharge branch pipe 209 a guides the exhaust fuel gas discharged from the SOFC cartridge 203 to the fuel gas discharge pipe 209. Further, the fuel gas discharge pipe 209 is connected to the plurality of fuel gas discharge branch pipes 209 a, and a part thereof is arranged outside the pressure vessel 205. The fuel gas discharge pipe 209 guides the exhaust fuel gas, which is discharged from the fuel gas discharge branch pipe 209a at a substantially uniform flow rate, to the outside of the pressure vessel 205.

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., so that the pressure vessel 205 has durability and corrosion resistance to an oxidizing agent 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 collected and housed in the pressure container 205, but the present invention is not limited to this, and for example, the SOFC cartridges 203 are not collected and the pressure is increased. It may be configured to be housed in the container 205.

As shown in FIG. 3, the SOFC cartridge 203 includes a plurality of cell stacks 101, a power generation chamber 215, a fuel gas supply chamber 217, a fuel gas discharge chamber 219, an oxidizing gas supply chamber 221, and an oxidizing gas discharge chamber. 223 and. The SOFC cartridge 203 also includes an upper tube plate 225a, a lower tube plate 225b, an upper heat insulator 227a, and a lower heat insulator 227b. In the present embodiment, the SOFC cartridge 203 has the fuel gas supply chamber 217, the fuel gas discharge chamber 219, the oxidizing gas supply chamber 221, and the oxidizing gas discharge chamber 223 arranged as shown in FIG. The fuel gas and the oxidizing gas are structured to flow inside and outside the cell stack 101 so as to face each other, but this is not always necessary. For example, the inside and outside of the cell stack may flow in parallel. Alternatively, the oxidizing gas may flow in a direction orthogonal to the longitudinal direction of the cell stack.

The power generation chamber 215 is a region formed between the upper heat insulator 227a and the lower heat insulator 227b. The power generation chamber 215 is a region in which the fuel cells 105 of the cell stack 101 are arranged, and a fuel gas and an oxidizing gas are electrochemically reacted to generate power. Further, the temperature near the central portion of the power generation chamber 215 in the longitudinal direction of the cell stack 101 becomes a high temperature atmosphere of about 700° C. to 1100° C. during the steady operation of the SOFC module 201.

The fuel gas supply chamber 217 is a region surrounded by the upper casing 229a of the SOFC cartridge 203 and the upper tube sheet 225a. Further, the fuel gas supply chamber 217 is connected to the fuel gas supply branch pipe 207a through a fuel gas supply hole 231a provided in the upper casing 229a. Further, in the fuel gas supply chamber 217, one end of the cell stack 101 is arranged such that the inside of the base tube 103 of the cell stack 101 is open to the fuel gas discharge chamber 219. The fuel gas supply chamber 217 guides the fuel gas supplied from the fuel gas supply branch pipe 207a through the fuel gas supply holes 231a into the base pipes 103 of the plurality of cell stacks 101 at a substantially uniform flow rate, and a plurality of fuel gas supply chambers 217a are provided. The power generation performance of the cell stack 101 is made substantially uniform.

The fuel gas discharge chamber 219 is an area surrounded by the lower casing 229b and the lower tube sheet 225b of the SOFC cartridge 203. Further, the fuel gas discharge chamber 219 communicates with the fuel gas discharge branch pipe 209a through a fuel gas discharge hole 231b provided in the lower casing 229b. Further, in the fuel gas discharge chamber 219, the other end of the cell stack 101 is arranged such that the inside of the base tube 103 of the cell stack 101 is open to the fuel gas discharge chamber 219. The fuel gas discharge chamber 219 collects the exhaust fuel gas that passes through the insides of the base pipes 103 of the plurality of cell stacks 101 and is supplied to the fuel gas discharge chamber 219, and the fuel gas is discharged through the fuel gas discharge holes 231b. It leads to the discharge branch pipe 209a.

Corresponding to the power generation amount of the SOFC module 201, an oxidizing gas having a predetermined gas composition and a predetermined flow rate is branched into an oxidizing gas supply branch pipe and supplied to a plurality of SOFC cartridges 203. The oxidizing gas supply chamber 221 is a region surrounded by the lower casing 229b, the lower tube plate 225b, and the lower heat insulator 227b of the SOFC cartridge 203. In addition, the oxidizing gas supply chamber 221 is connected to an oxidizing gas supply branch pipe (not shown) through an oxidizing gas supply hole 233a provided in the lower casing 229b. The oxidizing gas supply chamber 221 generates a predetermined flow rate of oxidizing gas supplied from an oxidizing gas supply branch pipe (not shown) through the oxidizing gas supply hole 233a through an oxidizing gas supply gap 235a described later. It leads to the chamber 215.

The oxidizing gas discharge chamber 223 is a region surrounded by the upper casing 229a, the upper tube sheet 225a, and the upper heat insulator 227a of the SOFC cartridge 203. Further, the oxidizing gas discharge chamber 223 is connected to an oxidizing gas discharge branch pipe (not shown) through an oxidizing gas discharge hole 233b provided in the upper casing 229a. The oxidizing gas discharge chamber 223 supplies the discharged oxidizing gas, which is supplied from the power generation chamber 215 to the oxidizing gas discharge chamber 223 via the oxidizing gas discharge gap 235b described later, through the oxidizing gas discharge hole 233b. It leads to a third oxidizing gas discharge branch pipe (not shown).

The upper tube plate 225a is arranged such that the upper tube plate 225a and the upper plate of the upper casing 229a are substantially parallel to the upper plate 225a between the upper plate of the upper casing 229a and the upper heat insulator 227a. It is fixed to the side plate. Further, 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 portion of the plurality of cell stacks 101 via one or both of the seal member and the adhesive member, and at the same time, the fuel gas supply chamber 217 and the oxidizing gas discharge chamber 223. It isolates and.

The lower tube plate 225b is provided on a 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 to each other between the bottom plate of the lower casing 229b and the lower heat insulator 227b. It is fixed. Further, the lower tube sheet 225b has a plurality of holes corresponding to the number of the 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 airtightly supports the other ends of the plurality of cell stacks 101 via one or both of the seal member and the adhesive member, and also the fuel gas discharge chamber 219 and the oxidizing gas supply chamber 221. It isolates and.

The upper heat insulator 227a is arranged 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. There is. Further, the upper heat insulator 227a is provided with a plurality of holes corresponding to the number of cell stacks 101 included in the SOFC cartridge 203. The diameter of this hole is set larger than the outer diameter of the cell stack 101. The upper heat insulator 227a has 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 partitions the power generation chamber 215 and the oxidizing gas discharge chamber 223, and the atmosphere around the upper tube sheet 225a is heated to a high temperature, and the strength is reduced and corrosion due to the oxidizing agent contained in the oxidizing gas is caused. Suppress increasing. The upper tube sheet 225a and the like are made of a metal material having high temperature durability such as Inconel, but when the upper tube sheet 225a and the like are exposed to the high temperature in the power generation chamber 215, the temperature difference in the upper tube sheet 225a and the like becomes large. It prevents thermal deformation. Further, the upper heat insulator 227a guides the exhausted oxidizing gas that has passed through the power generation chamber 215 and has been exposed to high temperature to the oxidizing gas exhaust chamber 223 through the oxidizing gas exhaust gap 235b.

According to the present embodiment, the structure of the SOFC cartridge 203 described above allows the fuel gas and the oxidizing gas to flow inside and outside the cell stack 101 so as to face each other. As a result, the exhausted oxidizing gas exchanges heat with the fuel gas supplied to the power generation chamber 215 through the inside of the base tube 103, and the upper tube sheet 225a made of a metal material causes buckling or the like. It is cooled to a temperature at which it is not deformed and supplied to the oxidizing gas discharge chamber 223. Further, the fuel gas is heated by heat exchange with the exhausted oxidizing gas discharged from the power generation chamber 215 and is supplied to the power generation chamber 215. As a result, the fuel 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 arranged on 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. .. Further, the lower heat insulator 227b is provided with a plurality of holes corresponding to the number of cell stacks 101 included in the SOFC cartridge 203. The diameter of this hole is set larger than the outer diameter of the cell stack 101. The lower heat insulator 227b has 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 partitions the power generation chamber 215 and the oxidizing gas supply chamber 221, and the atmosphere around the lower tube sheet 225b is heated to a high temperature and is not corroded by the oxidizing agent contained in the oxidizing gas. Suppress increasing. The lower tube sheet 225b and the like are made of a metal material having high temperature durability such as Inconel. However, when the lower tube sheet 225b and the like are exposed to high temperature, the temperature difference in the lower tube sheet 225b and the like becomes large, and thus the lower tube sheet 225b and the like are thermally deformed. To prevent. Further, 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 the present embodiment, the structure of the SOFC cartridge 203 described above allows the fuel gas and the oxidizing gas to flow inside and outside the cell stack 101 so as to face each other. As a result, the exhausted fuel gas that has passed through the inside of the base pipe 103 and passed through the power generation chamber 215 undergoes heat exchange with the oxidizing gas supplied to the power generation chamber 215, and the lower tube sheet 225b made of a metal material. Etc. are cooled to a temperature at which they do not deform such as buckling and are supplied to the fuel gas discharge chamber 219. Further, the oxidizing gas is heated by heat exchange with the exhaust fuel gas and is supplied to the power generation chamber 215. As a result, the oxidizing gas heated to the temperature required for power generation can be supplied to the power generation chamber 215 without using a heater or the like.

The DC power generated in the power generation chamber 215 is led 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 battery cells 105, and then the collector rod (not connected to the SOFC cartridge 203). Current is collected via a collector plate (not shown) in the drawing) and taken out to the outside of each SOFC cartridge 203. The electric power led to the outside of the SOFC cartridge 203 by the current collector is connected to the generated electric power of each SOFC cartridge 203 in a predetermined number of series and parallel, and is led to the outside of the SOFC module 201 to be illustrated. Not converted into a predetermined AC power by an inverter or the like and supplied to a power load.

The cylindrical cell stack according to this embodiment will be described with reference to FIG. Here, FIG. 4 shows one mode of the cell stack according to the present embodiment. The cell stack 101 has 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. In addition, the cell stack 101 is connected to the air electrode 113 of the fuel cell 105 formed at the end in the axial direction of the base tube 103 among the plurality of fuel cell 105 formed on the outer peripheral surface of the base tube 103. It has a lead film 115 electrically connected via a connector 107.

In the present embodiment, in the axial direction of the cell stack 101, the fuel cell 105 on the fuel gas inlet side of the cell stack 101 among the plurality of fuel cell 105 groups electrically connected by the interconnector 107 is From the temperature measurement point of the fuel gas inlet side power generation section 108a to the portion where the lead film 115 on the upstream side of the fuel gas flow is located, the internal reforming is actively carried out to generate hydrogen. It is a region where the temperature is reduced as it is generated.

The substrate tube 103 is made of a porous material, and is, for example, CaO-stabilized ZrO ₂ (CSZ), Y ₂ O ₃ -stabilized ZrO ₂ (YSZ), or MgAl ₂ O ₄ . The base tube 103 supports the fuel cell unit 105, the interconnector 107, and the lead film 115, and allows the fuel gas supplied to the inner peripheral surface of the base tube 103 to pass through the pores of the base tube 103. Is diffused to the fuel electrode 109 formed on the outer peripheral surface of the.

The fuel electrode 109 is composed of an oxide of a composite material of Ni and a zirconia-based electrolyte material, and for example, Ni/YSZ is used. 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 gas. This catalytic action causes a fuel gas supplied through the base pipe 103, for example, a mixed gas of methane (CH ₄ ) and steam to react with each other and reform it into hydrogen (H ₂ ) and carbon monoxide (CO). It is a thing. Further, the fuel electrode 109 interfaces hydrogen (H ₂ ) and carbon monoxide (CO) obtained by reforming and oxygen ions (O ²⁻ ) supplied via the solid electrolyte 111 with the solid electrolyte 111. It is an electrochemical reaction in the vicinity to generate water (H ₂ O) and carbon dioxide (CO ₂ ). At this time, the fuel cell unit 105 generates electricity by electrons emitted from oxygen ions.

The solid electrolyte 111 is mainly made of YSZ, which has gas-tightness that makes it difficult for gas to pass through and high oxygen ion conductivity at high temperatures. The solid electrolyte 111 moves oxygen ions (O ²⁻ ) generated in the air electrode 113 to the fuel electrode 109.

The air electrode 113 is made of, for example, LaSrMnO ₃ -based oxide or LaCoO ₃ -based oxide. The air electrode 113 dissociates oxygen in the oxidizing gas such as air supplied near the interface with the solid electrolyte 111 to generate oxygen ions (O ²⁻ ).

The interconnector 107 is composed of a conductive perovskite-type 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, and is composed of a fuel gas and an oxide. It is a dense film so that it does not mix with the volatile gas. Further, the interconnector 107 has stable electrical conductivity in both an oxidizing atmosphere and a 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 the 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 has a thermal expansion coefficient close to that of other materials forming the cell stack 101, Ni such as Ni/YSZ and a zirconia-based electrolyte material are required. Composed of composite material. The lead film 115 guides the DC power generated by the plurality of fuel cells 105 connected in series by the interconnector to the vicinity of the end of the cell stack 101.

Next, the operation of the fuel cell-hydrogen production system 2 according to this embodiment will be described. The fuel cell-hydrogen production system 2 is operated in a power generation mode or a hydrogen production mode.

(Power generation mode)
When the receiving unit 22 receives a command of the power generation from the outside, the operation mode control unit 23 opens the valve V ₁ on the basis of the finger decree, closing the valve V _2. At the same time, the operation mode control unit 23 controls the fuel gas flow rate, the recirculation flow rate, and the steam flow rate to the power generation mode conditions by adjusting the openings of the valves V ₃ , V ₄ , and V ₅ .

In the present embodiment, the conditions for the power generation mode such as the fuel gas flow rate, the recirculation flow rate, and the steam flow rate are, for example, system fuel utilization rate of 80% to 85%, one-pass fuel utilization rate of 50% to 60%, and S/C of 3 It is set in advance so as to be 0.5 to 5.0.

The fuel gas (FG1) containing hydrocarbon is supplied from the fuel gas supply source 11a to the SOFC module 201 via the fuel gas supply path 11b. The fuel gas (FG1) supplied to the SOFC module 201 is vigorously vaporized in the vicinity of the fuel electrode 109 of the fuel cell 105 of the cell stack 101, in particular, the fuel cell 105 of the fuel gas inlet side power generation section 108a on the fuel gas inlet side. Be modified. Here, the hydrocarbon contained in the fuel gas (FG1) undergoes an endothermic reaction with water vapor to generate hydrogen and carbon monoxide.

The fuel gas (FG2) containing hydrogen and carbon monoxide generated by the reforming is used for power generation in the power generation unit 108.

The fuel gas (exhaust fuel gas: FG3) that has passed through the power generation unit 108 is exhausted to the outside of the SOFC module 201 by the exhaust fuel gas path 13. A part of the exhaust fuel gas (FG3) is supplied to the combustor 32 of the gas turbine system 3 by the recirculation blower 15a. The other part of the exhaust fuel gas (FG3) is recirculated to the fuel gas supply path 11b by the recirculation blower 15a via the recirculation path 15b.

The exhaust fuel gas (FG3) supplied to the combustor 32 is burned with the fuel (F) in the exhaust oxidizing gas derived from the SOFC module 201. Combustion gas (CG1) generated by combustion is guided to the micro gas turbine 33, and drives the micro gas turbine 33 to rotate. As a result, power is generated by the generator 35. The combustion gas (CG2) that has passed through the micro gas turbine 33 is sent to the regenerative heat exchanger 34.

The air compressor 31 of the gas turbine system 3 sucks in air (A1) as an oxidizing gas, pressurizes the sucked air, and sends it to the regenerative heat exchanger 34. The air (A2) sent to the regenerative heat exchanger 34 is heated by the combustion gas (CG2) and then guided to the SOFC module 201 via the oxidizing gas supply path 12.

The combustion gas (CG3) that has passed through the regenerative heat exchanger 34 is guided to the exhaust heat recovery unit 4. The combustion gas (CG3) exchanges heat with water such as city water to generate steam (S). The water vapor may be recovered as a heat source and used in the water vapor supply source 16a or in another device. The exhaust combustion gas (CG3) that has passed through the exhaust heat recovery unit 4 is appropriately discharged as necessary, and then discharged to the atmosphere.

(Hydrogen production mode)
When the receiving unit 22 receives a command hydrogen production from the outside, the operation mode control unit 23 opens the valve V ₂ on the basis of the finger decree, closing the valve V _1. As a result, the exhaust fuel gas (FG3) discharged from the SOFC module 201 is guided to the shift reactor 18.

Carbon monoxide contained in the exhaust fuel gas (FG3) reacts with water in the shift reactor 18 in the presence of a shift catalyst to be converted into carbon dioxide (CO ₂ ). An iron oxide-based catalyst, an iron-chromium-based catalyst, or the like is used as the catalyst.

The exhaust fuel gas (FG4) that has passed through the shift reactor 18 is guided to the water separator 19 and cooled by heat exchange. As a result, water (drain water: D) is separated from the exhaust fuel gas (FG4). The exhaust fuel gas (FG5) that has passed through the water separator 19 becomes a dry gas with little water content.

The exhaust fuel gas (FG5) that has passed through the water separator 19 is guided to the hydrogen purification device 20. The hydrogen purifier 20 uses, for example, a PSA (Pressure Swing Adsorption) formula. Since the exhaust fuel gas (FG5) is a dry gas with separated water content, it does not deteriorate the performance of PSA. In the hydrogen purification device 20, hydrogen is separated and purified by adsorbing components other than hydrogen contained in the exhaust fuel gas (FG5) to the adsorbent.

The purified hydrogen (pure hydrogen) can be used for the fuel cell vehicle 21 and the like. The separated gas (for example, CH ₄ etc.) other than hydrogen is burned as off-gas (C), and the heat energy generated at this time is also used as steam in the exhaust heat recovery section 4 for heat recovery. good.

When the receiving unit 22 receives a hydrogen production command from the outside, the operation mode control unit 23 increases the opening degree of the valve V ₃ more than in the power generation mode operation and gradually increases the fuel gas flow rate. Thereby, the production amount of hydrogen can be increased. The operation mode control unit 23 adjusts the openings of the valves V ₄ and V ₅ to control the fuel gas flow rate, the recirculation flow rate, and the steam flow rate to the hydrogen production mode conditions, and controls the temperature of the fuel gas inlet side power generation unit 108a. Suppress the decrease of. This switches the operation of the fuel cell-hydrogen production system 2 to the hydrogen production mode.

Fuel gas flow rate, recirculation flow rate, and steam flow rate conditions for hydrogen production mode are as follows: system fuel utilization rate is 70% to 80%, one-pass fuel utilization rate is 40% to 60% (preferably 45% to 50%), S It is preset so that /C is 3.0 to 5.0 (preferably 3.5 to 5.0). If the one-pass fuel utilization rate is lowered too much, it is difficult to maintain the power generation unit 108 at a temperature (600°C to 950°C) suitable for power generation.

The temperature measurement unit 28 measures the temperature of the fuel gas inlet side power generation unit 108a and sends the temperature information obtained by the measurement to the control device 17. The transmission of the temperature information is intermittently and repeatedly performed at intervals of 30 minutes to 60 minutes. If the control device has a sufficient capacity, the temperature information may be continuously transmitted.

In the control device 17, the receiving unit 22 receives the temperature information, and the temperature control unit 24 controls the temperature of the fuel gas inlet side power generation unit 108a based on the temperature information.

An example of temperature control of the power generation unit 108 during the hydrogen production mode operation will be described with reference to FIG. 7. The heat absorption due to the internal reforming on the fuel gas inlet side of the cell stack 101 increases, the temperature of the fuel gas inlet side of the cell stack 101 decreases, and the temperature of the fuel gas inlet side power generation unit 108a decreases below a predetermined temperature and the cell stack 101 There is a case where the internal resistance of the fuel cell unit 105 increases as the temperature distribution of the SOFC module increases and the power generation performance of the SOFC module 201 decreases.

The temperature information of the fuel gas inlet side power generation unit 108a received by the reception unit is a predetermined temperature managed under each condition based on the central temperature (900° C. to 1000° C. in this embodiment) from the axial temperature distribution of the cell stack 101. A case will be described where the first predetermined temperature is 750° C., the second predetermined temperature is 740° C., the third predetermined temperature is 730° C., and the fourth predetermined temperature is 720° C., for example. Each predetermined temperature managed under each of these conditions may be appropriately changed depending on the implementation conditions, and is not limited.

When the temperature information of the fuel gas inlet side power generation unit 108a received by the reception unit 22 is higher than 750° C., the operation of the initial hydrogen production mode is continued until the next temperature information is received.

When the temperature information received by the reception unit 22 is, for example, 750° C. (first predetermined temperature) or less, the recirculation control unit 25 reduces the opening degree of the valve V ₄ to set the recirculation flow rate of the exhaust fuel gas to the set flow rate. Reduced by a minute. The set flow rate is, for example, -1% with respect to the initial recirculation flow rate.

Hydrocarbons that have not been reformed in the power generation unit 108 remain in the exhaust fuel gas. By reducing the recirculation flow rate of the exhaust fuel gas, the amount of hydrocarbons supplied to the fuel gas inlet side power generation section 108a is reduced, and the reforming reaction in the fuel gas inlet side power generation section 108a is suppressed. As a result, the amount of heat absorbed is reduced, so that the temperature decrease of the fuel gas inlet side power generation unit 108a can be suppressed.

The recirculated exhaust fuel gas has a lower temperature (400° C. to 450° C.) than that of the power generation unit 108. By reducing the recirculation flow rate of the exhaust fuel gas and reducing the amount of the exhaust fuel gas mixed with the fuel gas, it is possible to prevent the power generation unit from being cooled by heat transfer from the recirculated exhaust fuel gas.

Even if the recirculation flow rate of the exhaust fuel gas is reduced, power generation in the power generation unit 108 is continued. When the power generation unit 108 generates power, heat is generated, and the heat can raise the temperature of the power generation unit 108. When the temperature information received by the receiving unit 22 exceeds 750° C. after reducing the recirculation flow rate, the temperature control by the recirculation control unit 25 is stopped and the initial hydrogen production operation is performed until the next temperature information is received. Is done.

When the temperature information received by the reception unit 22 after the recirculation flow rate is reduced is still 750° C. or lower, the opening degree of the valve V ₄ is further reduced to reduce the recirculation flow rate of the exhaust fuel gas by, for example, −1%. .. The total limit of reduction of the recirculation flow rate by the recirculation control unit 25 is -5%. That is, if the temperature information received by the receiving unit is 750° C. or lower, if the initial recirculation flow rate decreases by -1%, the recirculation flow rate is reduced up to 5 times, and the fuel gas inlet side power generation is performed. The temperature of the part 108a is controlled.

When the temperature information received by the receiving unit 22 is, for example, 740° C. or lower (second predetermined temperature), the steam control unit 26 increases the opening degree of the valve V ₅ to increase the steam flow rate by the set flow rate. The set flow rate is, for example, +5% with respect to the initial steam flow rate.

When the flow rate of water vapor is increased, the hydrocarbon concentration in the fuel gas decreases, and the amount of hydrocarbons supplied to the fuel gas inlet side power generation section 108a decreases. As a result, the reforming endothermic amount is reduced, so that the temperature decrease of the fuel gas inlet side power generation unit 108a can be suppressed.

Even if the steam flow rate is reduced, the power generation unit 108 continues to generate power. When the power generation unit 108 generates power, heat is generated, and the heat can raise the temperature of the power generation unit 108. When the temperature information received by the reception unit 22 exceeds 740° C. after increasing the steam flow rate, the temperature control by the steam control unit 26 is stopped.

When the temperature information received by the reception unit 22 is 740° C. or less after increasing the steam flow rate, the opening degree of the valve V ₅ is further reduced to increase the recirculation flow rate of the exhaust fuel gas by, for example, +5%. The increase limit of the steam flow rate by the steam control unit 26 is set to +20% in total. That is, if the temperature information received by the receiving unit is 740° C. or lower, and if the initial steam flow rate is increased by, for example, +5%, the steam flow rate is increased up to four times and the fuel gas inlet-side power generation unit 108a is increased. Control the temperature of.

740°C or lower is included in the range of 750°C or lower. Therefore, when the temperature information received by the receiving unit is 740° C. or lower, the temperature control by the recirculation control unit 25 is also performed at the same time. However, the reduction of the recirculation flow rate by the recirculation control unit 25 is performed within the reduction limit.

When the temperature information received by the reception unit 22 is, for example, 730° C. (third predetermined temperature) or less, when the fuel control unit 27 has increased the opening degree of the valve V ₃ after switching to the hydrogen production mode, The increase of the opening degree of the valve V ₃ is stopped and the increase of the fuel gas flow rate is stopped.

If the fuel gas flow rate does not increase, the amount of hydrocarbons supplied to the fuel gas inlet-side power generation unit 108a does not change, and the amount of heat absorbed by the fuel gas inlet-side power generation unit 108a remains unchanged. Thereby, the temperature decrease of the power generation unit 108 can be suppressed.

Even if the increase in the fuel gas flow rate is stopped, the power generation unit 108 continues to generate power. When the power generation unit 108 generates power, heat is generated, and the heat can raise the temperature of the power generation unit 108. When the temperature information received by the receiving unit 22 exceeds 730° C. after stopping the increase of the fuel gas flow rate, the opening degree of the valve V ₃ is increased and the increase of the fuel gas flow rate is restarted.

When the temperature information received by the receiving unit 22 is 730° C. or less after stopping the increase of the fuel gas flow rate, the fuel gas flow rate is maintained as it is.

730°C or lower is included in the range of 740°C or lower and 750°C or lower. Therefore, when the temperature information received by the reception unit 22 is 730° C. or lower, the temperature control by the recirculation control unit 25 and the steam control unit 26 is also performed at the same time. However, the reduction of the recirculation flow rate by the recirculation control unit 25 is performed within the reduction limit. The increase of the steam flow rate by the steam control unit 26 is performed within the increase limit.

When the temperature information received by the receiving unit 22 is, for example, 720° C. (fourth predetermined temperature) or less, the fuel control unit 27 reduces the opening degree of the valve V ₃ to reduce the fuel gas flow rate by the set flow rate, and Sound an alarm. The set flow rate is, for example, -1% with respect to the initial fuel gas flow rate.

By reducing the fuel gas flow rate, the amount of hydrocarbons supplied to the fuel gas inlet side power generation section 108a is reduced, and the reforming reaction in the fuel gas inlet side power generation section 108a is suppressed. As a result, the amount of heat absorbed is reduced, so that the temperature decrease of the power generation unit 108 can be suppressed.

Even if the fuel gas flow rate is reduced, power generation in the power generation unit 108 is continued. When the power generation unit 108 generates power, heat is generated, and the heat can raise the temperature of the power generation unit 108. When the temperature information received by the reception unit 22 exceeds 720° C. after the fuel gas flow rate is reduced, the temperature control by the fuel control unit 27 is stopped. The alarm is canceled when the temperature information received by the receiver 22 exceeds 730°C.

When the temperature information received by the receiving unit 22 is 720° C. or less after reducing the fuel gas flow rate, the opening degree of the valve V ₃ is further reduced to reduce the fuel gas flow rate by, for example, −1%. The total limit of reduction of the fuel gas flow rate by the fuel control unit 27 is -2%. That is, if the temperature information received by the receiving unit 22 is 720° C. or less, the fuel gas flow rate is reduced up to twice when the temperature is reduced by −1% with respect to the initial fuel gas flow rate. The temperature of the side power generation unit 108a is controlled.

720°C or lower is included in the range of 740°C or lower and 750°C or lower. Therefore, when the temperature information received by the reception unit 22 is 720° C. or lower, the temperature control by the recirculation control unit 25 and the steam control unit 26 is also performed at the same time. However, the reduction of the recirculation flow rate by the recirculation control unit 25 is performed within the reduction limit. The increase of the steam flow rate by the steam control unit 26 is performed within the increase limit.

Even if the fuel gas flow rate is reduced to the lower limit by the fuel control unit 27, if the temperature information received by the reception unit 22 is 720° C. or less, the hydrogen production mode is switched to the power generation mode to increase the one-pass utilization rate. adjusting the opening of the valve _{V 3, V 4.}

According to the test using the SOFC cartridge 203, when the system fuel utilization rate is reduced from 82% to, for example, 75% or less, the one-pass fuel utilization rate will be reduced unless the temperature control section 24 controls the temperature of the power generation section 108. It decreased from 51% to 41%, and the temperature of the power generation section 108 dropped, so that the power generation output could not be maintained. On the other hand, by controlling the temperature of the power generation unit 108 by the temperature control unit 24 and setting the one-pass utilization rate to, for example, 45% or more, the temperature of the power generation unit 108 and the power generation output could be maintained.

Although the first predetermined temperature is higher than the second predetermined temperature in FIG. 7, these may be reversed. That is, when the temperature information received by the receiver 22 is 750° C. or lower, the control by the water vapor controller 26 is performed, and when the temperature information received by the receiver 22 is 740° C. or lower, the recirculation control is performed. The control in the unit 25 may be performed. However, since the generation of water vapor requires energy, the temperature of the power generation unit 108 can be efficiently controlled by giving priority to the control by the recirculation control unit 25.

Although the first predetermined temperature is higher than the second predetermined temperature in FIG. 7, these may be reversed. That is, when the temperature information received by the reception unit 22 is 750° C. or lower, the control by the water vapor control unit 26 is performed, and when the temperature information received by the reception unit 22 is 740° C. or lower, the recirculation control is performed. The control in the unit 25 may be performed.

8A to 8E are graphs for explaining operating conditions in the hydrogen production mode of the fuel cell-hydrogen production system. FIG. 8A is a graph showing the transition of power generation output. In the figure, the vertical axis represents the power generation output, and the horizontal axis represents the hydrogen production flow rate. FIG. 8B is a graph showing the transition of the fuel gas flow rate. In the figure, the vertical axis represents the fuel gas flow rate, and the horizontal axis represents the hydrogen production flow rate. FIG. 8C is a graph showing the transition of the recirculation flow rate of the exhaust fuel gas. In the figure, the vertical axis represents the recirculation flow rate, and the horizontal axis represents the hydrogen production flow rate. FIG. 8D is a graph showing the transition of the steam flow rate. In the figure, the vertical axis represents the steam flow rate and the horizontal axis represents the hydrogen production flow rate. FIG. 8E is a graph showing the transition of S/C in the gas supplied to the fuel gas inlet side power generation unit 108a. In the figure, the vertical axis represents S/C and the horizontal axis represents hydrogen production flow rate.

In FIGS. 8A to 8E, the left end of the horizontal axis of the hydrogen production flow rate on the paper shows the hydrogen production flow rate=0, which corresponds to the case of the power generation mode. Even when switching to the hydrogen production mode and increasing the hydrogen production flow rate on the horizontal axis, the power generation output of (a) is not reduced. To this end, the cell stack 101 is adjusted by adjusting the fuel gas flow rate in FIG. 8B, the exhaust fuel gas recirculation flow rate in FIG. 8C, the water vapor flow rate in FIG. 8D, and the S/C in FIG. 8E. It is possible to control so that the temperature of the fuel gas inlet side does not decrease below a predetermined temperature and the temperature distribution of the cell stack 101 increases.

The arrows (↓) in (a) to (e) of FIG. 8 indicate the timing when the valve V ₁ and the valve V ₂ are the flow rate adjustment amount valves and the opening degree is gradually increased to reach a predetermined opening degree. There, in the case of valve V ₁ and valve V ₂ is shut-off valve, the operation mode control unit 23 opens the valve V _2, a timing of closing the valve V _1. When the flow path of the exhaust fuel gas (FG3) is switched, hydrogen, carbon monoxide, and steam are contained in the exhaust fuel, and carbon monoxide and steam react in the shift reactor 18 to produce hydrogen. Therefore, the hydrogen production flow rate increases to some extent without increasing the fuel gas flow rate.

In order to further increase the hydrogen production flow rate, the fuel gas flow rate is increased to reduce the one-pass fuel utilization rate. When the fuel gas flow rate is increased, the hydrogen production flow rate is also increased, but the hydrocarbon concentration in the exhaust fuel gas is increased, the reforming endothermic amount in the fuel gas inlet side power generation section 108a is increased, and the fuel gas inlet side power generation section 108a is increased. Therefore, the temperature of the power generation unit 108 is lowered. To prevent these, the recirculation flow rate is reduced and the steam flow rate is increased. When the fuel gas flow rate is increased, the S/C decreases. If S/C is lowered too much, carbon may precipitate in the power generation unit 108. Further, if S/C is lowered, the hydrocarbon concentration in the exhaust fuel gas increases, the reforming endothermic amount increases, and the temperature distribution in the power generation unit 108 becomes wider. Therefore, it is advisable to keep the S/C substantially constant so as not to lower it too much.

By controlling the fuel gas flow rate, the recirculation flow rate, and the steam flow rate as shown in (b) to (e) of FIG. 8, hydrogen can be produced while keeping the power generation output constant as shown in (a) of FIG.

1 Integrated Power Generation System 2 Fuel Cell-Hydrogen Production System 3 Gas Turbine System 4 Exhaust Heat Recovery Section 11a Fuel Gas Supply Source 11b Fuel Gas Supply Path 12 Oxidizing Gas Supply Path 13 Exhaust Fuel Gas Path 14 Exhaust Oxidizing Gas Path 15a Recirculation Blower 15b Recirculation path 16a Steam supply source 16b Steam supply path 17 Controller 18 Shift reactor 19 Water separator 20 Hydrogen purifier 21 Fuel cell vehicle 22 Receiver 23 Operating mode controller 24 Temperature controller 25 Recirculation controller 26 Water vapor control unit 27 Fuel control unit 31 Air compressor 32 Combustor 33 Micro gas turbine 34 Regenerative heat exchanger 35 Generator 101 Cell stack 103 Base tube 105 Fuel cell 107 Interconnector 108 Power generation unit 108a Fuel gas inlet side power generation unit 109 Fuel electrode 111 Solid electrolyte 113 Air electrode 115 Lead film 201 SOFC module 203 SOFC cartridge 205 Pressure vessel 207 Fuel gas supply pipe 207a Fuel gas supply branch pipe 209 Fuel gas discharge pipe 209a Fuel gas discharge branch pipe 215 Power generation chamber 217 Fuel gas supply chamber 219 Fuel gas discharge chamber 225a Upper tube plate 225b Lower tube plate 229a Upper casing 229b Lower casing 231a Fuel gas supply hole 231b Fuel gas discharge hole

Claims (14)

A power generation unit having a cell that generates power by a reaction between a fuel gas and an oxidizing gas,
A fuel gas supply unit for supplying the fuel gas to the power generation unit;
An oxidizing gas supply unit that supplies the oxidizing gas to the power generation unit,
A steam supply unit for supplying steam to the fuel gas supply unit;
A temperature measuring unit for measuring the temperature of the fuel gas inlet side power generating unit installed on the fuel gas inlet side of the power generating unit,
A temperature control unit for controlling the temperature of the fuel gas inlet side power generation unit,
In response to a hydrogen production command, an operation mode control unit that increases the flow rate of the fuel gas,
A recirculation unit for recirculating at least a part of the exhaust fuel gas discharged from the power generation unit to the fuel gas supply unit;
Equipped with
It said temperature control unit comprises a recirculation control unit for controlling the recirculation flow of the exhaust fuel gas in accordance with the temperature of the fuel gas inlet-side power generation section measured by the temperature measuring section,
The recirculation control unit has a function of reducing the recirculation flow rate of the exhaust fuel gas by a set flow rate when the temperature of the fuel gas inlet side power generation section is equal to or lower than a predetermined temperature. system. A power generation unit having a cell that generates power by a reaction between a fuel gas and an oxidizing gas,
A fuel gas supply unit for supplying the fuel gas to the power generation unit;
An oxidizing gas supply unit that supplies the oxidizing gas to the power generation unit,
A steam supply unit for supplying steam to the fuel gas supply unit;
A temperature measuring unit for measuring the temperature of the fuel gas inlet side power generating unit installed on the fuel gas inlet side of the power generating unit,
A temperature control unit for controlling the temperature of the fuel gas inlet side power generation unit,
In response to a hydrogen production command, an operation mode control unit that increases the flow rate of the fuel gas,
Equipped with
The temperature control unit includes a steam control unit that controls the flow rate of the steam according to the temperature of the fuel gas inlet side power generation unit measured by the temperature measurement unit,
The steam control unit, wherein when the temperature of the fuel gas inlet-side power generation part is a predetermined temperature or less, the flow rate set flow amount of the steam, fuel cells that have the ability to increase - hydrogen production system. A power generation unit having a cell that generates power by a reaction between a fuel gas and an oxidizing gas,
A fuel gas supply unit for supplying the fuel gas to the power generation unit;
An oxidizing gas supply unit that supplies the oxidizing gas to the power generation unit,
A steam supply unit for supplying steam to the fuel gas supply unit;
A temperature measuring unit that measures the temperature of the fuel gas inlet side power generating unit installed on the fuel gas inlet side of the power generating unit,
A temperature control unit for controlling the temperature of the fuel gas inlet side power generation unit,
In response to a hydrogen production command, an operation mode control unit that increases the flow rate of the fuel gas,
A recirculation unit for recirculating at least a part of the exhaust fuel gas discharged from the power generation unit to the fuel gas supply unit;
Equipped with
The temperature control unit controls the recirculation flow rate of the exhaust fuel gas according to the temperature of the fuel gas inlet side power generation unit measured by the temperature measurement unit, and the temperature measurement unit measures the temperature. A steam control unit that controls the flow rate of the steam according to the temperature of the fuel gas inlet side power generation unit;
The recirculation control unit has a function of reducing the recirculation flow rate of the exhaust fuel gas by a set flow rate when the temperature of the fuel gas inlet side power generation section is equal to or lower than a first predetermined temperature,
The water vapor control unit has a function of increasing the flow rate of the water vapor by a set flow rate when the temperature of the fuel gas inlet side power generation unit is equal to or lower than a second predetermined temperature,
Wherein the first predetermined temperature is a temperature der Ru fuel cell different from the second predetermined temperature - hydrogen production system. The fuel cell-hydrogen production system according to claim 3 , wherein the first predetermined temperature is higher than the second predetermined temperature. A fuel control unit that controls the temperature control unit to stop increasing the flow rate of the fuel gas when the temperature of the fuel gas inlet side power generation unit measured by the temperature measurement unit is equal to or lower than a third predetermined temperature. wherein said third predetermined temperature, the fuel cell according to claim 3 or claim 4 wherein the first is a predetermined temperature and said second temperature lower than the predetermined temperature - hydrogen production system. The fuel control unit has a function of reducing the flow rate of the fuel gas by a set flow rate when the temperature of the fuel gas inlet-side power generation section is equal to or lower than a fourth predetermined temperature, and the fourth predetermined temperature is equal to the fourth predetermined temperature. 3. The fuel cell-hydrogen production system according to claim 5 , wherein the temperature is lower than a predetermined temperature. Has a warning part that issues a warning,
The fuel control unit, the warning issued when the temperature of the fuel gas inlet-side power generation unit is equal to or less than the fourth predetermined temperature, the temperature of the fuel gas inlet-side power generation part exceeds the third predetermined temperature the The fuel cell-hydrogen production system according to claim 6 , further comprising a function of controlling the warning unit to cancel a warning. A step of supplying hydrocarbon and steam to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide;
Supplying a fuel gas containing the hydrogen and the carbon monoxide and an oxidizing gas to the power generation unit to generate power;
A step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section;
Controlling the temperature of the fuel gas inlet side power generation section,
Receiving a command for hydrogen production, increasing the flow rate of the fuel gas,
Recirculating at least a part of the exhausted fuel gas discharged from the power generation unit to the upstream side of the power generation unit;
Equipped with
Step of controlling the temperature of said fuel gas inlet-side power generation unit comprises a control step A for controlling the recirculation flow of the exhaust fuel gas in accordance with the measured temperature of the fuel gas inlet-side power generation unit,
In the control step A, a method of operating a fuel cell-hydrogen production system , which reduces the recirculation flow rate of the exhaust fuel gas by a set flow rate when the temperature of the fuel gas inlet side power generation section is equal to or lower than a predetermined temperature . A step of supplying hydrocarbon and steam to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide;
Supplying a fuel gas containing the hydrogen and the carbon monoxide and an oxidizing gas to the power generation unit to generate power;
A step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section;
Controlling the temperature of the fuel gas inlet side power generation section,
Receiving a command for hydrogen production, increasing the flow rate of the fuel gas,
Equipped with
The step of controlling the temperature of the fuel gas inlet side power generation section includes a control step B of controlling the flow rate of the water vapor according to the measured temperature of the fuel gas inlet side power generation section, and in the control step B, the fuel gas when the temperature of the inlet-side power generation part is a predetermined temperature or less, the flow rate set flow amount of the steam, fuel cell Ru increases - the method of operating the hydrogen manufacturing system. A step of supplying hydrocarbon and steam to the power generation section to cause an endothermic reaction to generate hydrogen and carbon monoxide;
Supplying a fuel gas containing the hydrogen and the carbon monoxide and an oxidizing gas to the power generation unit to generate power;
A step of measuring the temperature of the fuel gas inlet side power generating section installed on the fuel gas inlet side of the power generating section;
Controlling the temperature of the fuel gas inlet side power generation section,
Receiving a command for hydrogen production, increasing the flow rate of the fuel gas,
Recirculating at least a part of the exhausted fuel gas discharged from the power generation unit to the upstream side of the power generation unit;
Equipped with
The step of controlling the temperature of the fuel gas inlet side power generation section controls the recirculation flow rate of the exhaust fuel gas according to the measured temperature of the fuel gas inlet side power generation section, and the fuel gas inlet side Including a control step B for controlling the flow rate of the water vapor according to the measured temperature of the power generation unit, and setting a first predetermined temperature and a second predetermined temperature which is a temperature different from the first predetermined temperature,
In the control step A, when the temperature of the fuel gas inlet side power generation part is equal to or lower than the first predetermined temperature, the recirculation flow rate of the exhaust fuel gas is reduced by a set flow rate,
In the control step B, wherein when the temperature of the fuel gas inlet-side power generation unit is equal to or less than the second predetermined temperature, the flow rate set flow amount of the steam, fuel cell Ru increases - the method of operating the hydrogen manufacturing system. The method for operating a fuel cell-hydrogen production system according to claim 10 , wherein the first predetermined temperature is higher than the second predetermined temperature. When a third predetermined temperature that is lower than the first predetermined temperature and the second predetermined temperature is set and the measured temperature of the fuel gas inlet side power generation unit is equal to or lower than the third predetermined temperature, the fuel gas The method for operating the fuel cell-hydrogen production system according to claim 10 or 11 , further comprising the step of controlling to stop the increase of the flow rate of the fuel cell. When a fourth predetermined temperature which is lower than the third predetermined temperature is set and the measured temperature of the fuel gas inlet side power generation part is equal to or lower than the fourth predetermined temperature, the flow rate of the fuel gas is set by a set flow rate, The method for operating a fuel cell-hydrogen production system according to claim 12 , wherein the fuel cell is reduced. A warning is issued when the measured temperature of the fuel gas inlet side power generation section is equal to or lower than the fourth predetermined temperature, and the warning is canceled when the temperature of the fuel gas inlet side power generation section exceeds the third predetermined temperature. 13. The method for operating the fuel cell-hydrogen production system according to item 13 .

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