JP6025521B2 - Combined power generation system and method of operating combined power generation system - Google Patents

Description

  The present invention relates to a combined power generation system in which a fuel cell such as a high-temperature fuel cell and a gas turbine, a micro gas turbine, or a gas engine as an internal combustion engine are combined, and an operation method thereof.

A fuel cell is a power generation device that uses a power generation method based on an electrochemical reaction, and has excellent power generation efficiency and environmental characteristics. For this reason, research and development for practical use is progressing as an urban energy supply system for the 21st century.
Such a fuel cell is composed of a fuel electrode that is an electrode on the fuel side, an air electrode that is an electrode on the air (oxidant) side, and an electrolyte that passes only ions between them. Various formats have been developed depending on the type.

Among these, solid oxide fuel cells (hereinafter referred to as “SOFC”) use ceramics such as zirconia ceramics as an electrolyte, such as city gas, natural gas, petroleum, methanol, and coal gasification gas. Is a fuel cell operated using as a fuel. This SOFC has a high operating temperature of about 700 to 1000 ° C. in order to increase the ionic conductivity, and is known as a high-efficiency high-temperature fuel cell that is versatile.
In such an SOFC, in order to prevent deterioration due to the reduction of the air electrode and the oxidation of the fuel electrode due to the stoppage of power generation, the fuel electrode side is purged with an inert gas such as nitrogen after the fuel cell is stopped. ing. (See Patent Documents 1 and 2)

JP 2006-100153 A JP 2010-146934 A

By the way, the above-described prior art documents disclose purging nitrogen gas when temporarily stopping SOFC, and maintaining the pressure vessel in a pressurized state when the operation is stopped. However, in a combined power generation system combined with a gas turbine, it is necessary to hold the SOFC without affecting the durability of the SOFC itself and taking time to restart.
Specifically, power generation by a gas turbine is shorter than the other power generation methods, so the start time and stop time are shorter, so operation that stops at night when power demand is low and restarts the next morning when power demand increases. It is suitable for so-called DSS (Daily Start and Stop) operation, and according to the power generation demand (power generation load), the power generation of the SOFC is temporarily stopped while the gas turbine is operated.

Therefore, in a combined power generation system that generates power by combining a SOFC and a gas turbine, the SOFC itself for starting / stopping the SOFC is a highly reliable system that can easily handle repeated frequent operation / stopping. There is a need to improve the durability of the engine and to shorten the time required from the temporary stop of the SOFC to the restart of operation (restart). That is, in the combined power generation system, when the SOFC is temporarily stopped in a state where the gas turbine is normally operated, the time for the operation to shift to the hot standby state in which the power generation chamber is lowered to the predetermined temperature and maintained, and It is desired to reduce the time required for restart by maintaining the hot standby state.
Here, in the hot standby state, although the power generation of the SOFC itself is temporarily stopped, the temperature of the SOFC power generation chamber portion is 400 ° C. or higher, more preferably the power generation chamber temperature is 700 ° C. or higher, This is a standby state in which power generation can be resumed in a short time by re-injecting a predetermined gas into the air electrode side.

However, when the SOFC operation is temporarily stopped, the amount of self-heating is reduced due to a decrease in load, and the temperature of the power generation chamber is decreased. Therefore, in order to shorten the time required for restarting, the power generation chamber is set to a predetermined value. A temperature maintenance measure for maintaining the above high temperature is required.
The present invention has been made in order to solve the above-mentioned problems. The object of the present invention is to improve the durability of the SOFC itself against frequent repetitions of starting and stopping, and to restart from the temporary stop of the SOFC. An object of the present invention is to provide a combined power generation system and a method for operating the combined power generation system that can shorten the time required for startup.

In order to solve the above problems, the present invention employs the following means.
The combined power generation system according to the present invention generates an electric power by combining a fuel cell and an internal combustion engine, and has an operation mode for shifting the fuel cell to a standby state when the fuel cell is stopped in a state where the internal combustion engine is operated. a combined cycle power generation system comprising, as a for temperature maintenance during the transition and the standby state to the standby state, is provided a heating unit for raising the temperature of the power generation chamber, wherein the operation mode, the fuel cell When the stop command is output, the first step of reducing the load to the load factor of the first stage of the fuel cell and the second step of reducing the load to the load factor of the second stage are executed, The second step is executed after the load factor set in the first step is reached, and when the first step is executed, a third step is performed for injecting the combustion gas in the furnace into the fuel cell. It is characterized in performing a flop.
In the operation mode, it is preferable that when the second step is executed, a fourth step of supplying water vapor to the fuel cell is executed.

  According to the combined power generation system of the present invention configured as described above, since the heating unit for raising the temperature in the power generation chamber is provided at the time of transition to the standby state and for maintaining the temperature of the standby state, In the SOFC power generation chamber, it is possible to compensate for the decrease in the amount of self-heating by heating the heating unit. Therefore, the time required for restarting the SOFC can be shortened by performing the operation in the hot standby state in which the power generation chamber is maintained at a desired temperature.

  In the above combined power generation system, the heating unit oxidizes the fuel input to the air electrode side of the power generation chamber to generate heat and generates compressed air from the internal combustion engine to the air electrode side of the power generation chamber. Catalytic combustion in which fuel is introduced into a catalytic combustor installed in a supply flow path and burned can be employed. In particular, if catalytic combustion is employed, it is possible to realize a standby operation in which the amount of fuel consumed for heating is small.

  In the above combined power generation system, the combined power generation system according to the present invention preferably includes a flow path heating unit in a fuel flow path connecting between the fuel cell and the internal combustion engine. Can be easily maintained at a desired temperature.

  An operation method of a combined power generation system according to the present invention is an operation method of a combined power generation system including an operation mode in which a fuel cell and an internal combustion engine are combined to generate power and the fuel cell is stopped while the internal combustion engine is operated. In the operation mode, when a stop command for the fuel cell is output, the first step of reducing the load to the first stage load factor of the fuel cell and the load to the second stage load factor are performed. The second step is executed after the load factor set by the first step is reached, and when the first step is executed, the fuel is reduced. The third step of introducing the combustion gas in the furnace into the battery is performed.

  According to such an operation method of the combined power generation system of the present invention, in the operation mode in which the power generation is performed by combining the fuel cell and the internal combustion engine, and the fuel cell is stopped while the internal combustion engine is operated, the stop command for the fuel cell is issued. Is output, the first step of reducing the load to the load factor of the first stage of the fuel cell and the second step of reducing the load to the load factor of the second stage are executed, and the second step Is executed after reaching the load factor set in the first step, and when the first step is executed, the third step of injecting the combustion gas in the furnace into the fuel cell is executed. The durability of the SOFC itself can be improved against frequent repetition of the stop, and the time required from the temporary stop to restart of the SOFC can be shortened.

  In the operation method of the above combined power generation system, it is preferable that when the second step is executed, the fourth step of supplying water vapor to the fuel cell is executed.

  According to the combined power generation system and the operation method of the combined power generation system of the present invention described above, it is possible to improve the durability of the SOFC itself with respect to frequent repetition of starting and stopping, and also the time required from the temporary stop to restart of the SOFC. Can be shortened.

BRIEF DESCRIPTION OF THE DRAWINGS It is a systematic diagram which shows 1st Embodiment regarding the operating method of the combined power generation system and combined power generation system which concern on this invention. It is sectional drawing which shows the structural example of a power generation chamber about the solid oxide fuel cell (SOFC) which comprises the combined power generation system shown in FIG. It is explanatory drawing which shows the structural example of a cartridge, and the function of each element about a solid oxide fuel cell (SOFC). It is the systematic diagram which expanded the gas turbine (MGT) periphery which comprises the combined power generation system shown in FIG. 3 is a flowchart according to the first embodiment. It is a systematic diagram which shows 2nd Embodiment regarding the operating method of the combined power generation system and combined power generation system which concern on this invention. It is a flowchart concerning a 2nd embodiment.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a combined power generation system and a combined power generation system operation method according to the present invention will be described with reference to the drawings.
In the first embodiment shown in FIG. 1, a combined power generation system (power generation system using a fuel cell / internal combustion engine) 1 includes a SOFC 10 that is a high-temperature fuel cell, a micro turbine as an example of a gas turbine or a gas engine that is an internal combustion engine. By combining with a gas turbine (hereinafter referred to as “MGT”) 50, efficient power generation is performed.

In other words, in addition to SOFC10 that receives supply of fuel gas such as city gas (natural gas) and oxidizing gas such as air and generates electricity through an electrochemical reaction via an electrolyte, high-temperature exhaust fuel discharged after power generation from SOFC10 The exhaust gas is introduced to operate the MGT 50, and a generator (not shown) connected to the output shaft of the MGT 50 is driven to generate power.
Furthermore, if high-temperature combustion exhaust gas discharged from the MGT 50 is introduced into the exhaust heat recovery boiler, it is possible to construct a combined power generation system combined with power generation by a steam turbine.

  Below, the combined power generation system 1 which employ | adopted SOFC10 mentioned above is demonstrated. This SOFC10 uses ceramics such as zirconia ceramics as an electrolyte and operates (power generation) using city gas, natural gas, petroleum, methanol, coal gasification gas, etc. as fuel, and has an operating temperature to increase ionic conductivity. Is set as high as about 700-1000 degreeC. Such a SOFC 10 is configured by appropriately combining one or a plurality of SOFC modules. The SOFC module includes a plurality of SOFC cartridges 11 (see FIGS. 2 and 3) and a pressure vessel 81 that stores the plurality of SOFC cartridges 11.

As shown in FIG. 3, the SOFC cartridge 11 includes a plurality of cell stacks 12, a power generation chamber 13, a fuel gas supply chamber 14, a fuel gas discharge chamber 15, an oxidizing gas supply chamber 16, and an oxidizing gas discharge chamber. 17. The SOFC cartridge 11 includes an upper tube plate 18a, a lower tube plate 18b, an upper heat insulator 19a, and a lower heat insulator 19b.
The SOFC cartridge 11 of the present embodiment includes a fuel gas supply chamber 14, a fuel gas discharge chamber 15, an oxidizing gas supply chamber 16, and an oxidizing gas discharge chamber 17 as shown in the figure, so that the fuel gas and the oxidation chamber 17 are oxidized. This is a structure in which the property gas flows oppositely between the inside and the outside of the cell stack 12. However, it is not necessarily limited to this arrangement and configuration. For example, the inner and outer sides of the cell stack flow in parallel, or the oxidizing gas flows in a direction perpendicular to the longitudinal direction of the cell stack. Also good.

The oxidizing gas described above is a gas containing about 15 to 30% oxygen, and typically air is suitable. However, in addition to air, a mixed gas of combustion exhaust gas and air, a mixed gas of oxygen and air, or the like can be used.
In the following description, a case will be described in which city gas is reformed outside or inside the SOFC 10 as fuel and air is used as an oxidizing gas. In this case, compressed air supplied from the MGT 50 is used. And so on.

For example, as shown in FIG. 4, the MGT 50 includes a compressor 51, a combustor 52, and a turbine 53. In the figure, reference numeral 54 is a filter, and 55 is a regenerative heat exchanger.
The compressor 51 compresses the atmosphere (air) introduced through the filter 54, and the driving source in this case is the turbine 53. The compressed air compressed by the compressor 51 is supplied to the SOFC or the like via the combustor 52 and the regenerative heat exchanger 55.
The combustor 52 is supplied with compressed air, burns city gas as fuel, generates high-temperature and high-pressure combustion exhaust gas, and supplies the combustion exhaust gas to the turbine 53. The compressed air supplied to the combustor 52 is supplied from a compressed air supply system that branches from the front of the regenerative heat exchanger 55 when the MGT 50 is operating alone. Further, when the MGT 50 and the SOFC 10 are performing combined power generation, the compressed air is supplied with an oxidizing gas that is used for the power generation of the SOFC 10 and discharged.

The turbine 53 is rotated by the energy of the combustion exhaust gas to generate a shaft output, and the compressor 51 and a generator (not shown) are driven using this shaft output.
The combustion exhaust gas that has worked in the turbine 53 is heated by regenerative heat exchanger 55 by heat exchange with compressed air, and then released from the chimney 60 to the atmosphere.

The combined power generation system 1 shown in FIG. 1 is a system that generates power by combining the SOFC 10 and the MGT 50. The fuel supply system 20 that supplies fuel to the fuel electrode and the oxidizing gas supply that supplies oxidizing gas to the air electrode. A system 70 is provided.
The illustrated fuel supply system 20 includes a city gas (fuel gas) supply line 22 having an on-off valve 21, a nitrogen gas supply line 24 having an on-off valve 23, and a water vapor supply line 26 having an on-off valve 25. It has. The nitrogen gas supply line 24 and the water vapor supply line 26 are both connected to the downstream side of the on-off valve 21.

  The illustrated fuel gas discharge system 27 is a flow path for supplying the fuel supplied to the SOFC 10 to the MGT 50. The fuel gas discharge system 27 includes a flow rate adjusting valve 28, an exhaust fuel line 27a having an exhaust fuel blower 29, a recirculation line 27b for recirculating the exhaust fuel gas to the SOFC 50 via the exhaust fuel line 27a, and an exhaust fuel line. The exhaust fuel supply line 27c is connected to the MGT 50 via 27a. The recirculation line 27 b returns the exhaust fuel gas of the SOFC 10 to the fuel supply system 20 via the flow rate adjustment valve 30.

The illustrated oxidizing gas supply system 70 is a flow path for supplying compressed air compressed by the compressor 51 of the MGT 50 to the air electrode of the SOFC 10. The oxidizing gas supply system 70 supplies the compressed air heat-exchanged by the regenerative heat exchanger 55 to the SOFC 10, and a flow rate adjusting valve 71 is provided in the middle of the flow path.
The oxidizing gas discharge system 72 is a flow path for supplying the oxidizing gas discharged from the SOFC 10 to the MGT 50, and an open / close valve 73 is provided in the flow path connecting the SOFC 10 and the MGT 50. .

In the combined power generation system 1 configured as described above, an operation mode for shifting to a hot standby state in which the inside of the power generation chamber 13 of the SOFC 10 is maintained at a predetermined temperature while the MGT 50 is operated in accordance with power demand, that is, the power generation chamber of the SOFC 10 An operation mode (hereinafter referred to as a “hot standby operation mode”) is performed in which a predetermined hot standby state is maintained until the operation is resumed while a transition is made to a hot standby state in which the inside 13 is maintained at a predetermined temperature.
In the present embodiment, a heating unit (heating means) for raising the temperature in the power generation chamber 13 is provided for shifting to the hot standby state and for maintaining the temperature in the hot standby state. In the heating section, in-furnace combustion is employed in which fuel injected into the air electrode side of the power generation chamber 13 is combusted.

  The hot standby operation mode of the present embodiment is an operation operation in which the internal temperature of the power generation chamber 13 is lowered to a set predetermined temperature and the predetermined temperature is maintained until the operation of the SOFC 10 is resumed in order to place the SOFC 10 in a standby state. . In this case, the predetermined temperature of the internal temperature set in the power generation chamber 13 is, for example, 400 ° C. or more as a temperature at which the power generation of the SOFC 10 can be resumed in a short time and the temperature can be maintained for a long time in the power generation chamber 13 of the SOFC Is set.

  In this embodiment, the load factor of the SOFC 10 is set to a low load state, and the city gas flow rate and the air flow rate corresponding to the load factor are supplied from the city gas supply line 22 and the oxidizing gas supply system 70 to the SOFC 10. Further, depending on the load factor, the SOFC 10 is shifted to the standby state via the steam supply from the steam supply line 26 to the fuel electrode.

In the hot standby operation mode, reducing the load of the SOFC 10 reduces the amount of self-heating generated by the SOFC 10 generating power.
Therefore, in the SOFC 10, in order to maintain the internal temperature of the power generation chamber 13 within a predetermined temperature range, it is desirable to compensate for the decrease in the amount of self-heating due to power generation, and for this reason, heating by furnace combustion is performed. In the furnace combustion, fuel city gas is injected into the air electrode side in the power generation chamber 13 and the city gas is burned in the power generation chamber 13. The calorific value generated by the combustion of the city gas is used. It has heating means for raising the temperature.

The in-furnace combustion in the present embodiment may be in-furnace combustion in the power generation chamber 13, or a catalytic combustor 80 (a second to be described later) provided in the compressed air flow path in the vicinity of the power generation chamber 13. The heating means such as the embodiment may be used.
In FIG. 1, a fuel supply line 75 including an on-off valve 74 is provided on the downstream side of the flow rate adjustment valve 71 of the oxidizing gas supply system 70 as a furnace combustion gas supply system path.

In the hot standby operation mode in the present embodiment, in the combined power generation system of the SOFC 10 and the MGT 50, a combined state in which the fuel gas and the oxidizing gas discharged from the SOFC 10 are supplied to the combustor 52 of the MGT 50 is maintained. Therefore, the compressed air from the MGT 50 is supplied to the SOFC 10 and the supply of city gas (fuel gas) from the fuel supply system 20 is continued.
In the hot standby operation mode, fuel gas is supplied to the MGT 50 via the SOFC 10, but necessary auxiliary fuel may be supplied from the fuel supply line 76 according to the state of the MGT 50. The SOFC 10 is supplied with 400-450 ° C. compressed air from the MGT 50 and is also used to maintain the temperature of the SOFC 50 in the hot standby operation mode.

  Since the internal temperature of the power generation chamber 13 is maintained at a predetermined temperature of 400 ° C. or higher by the hot standby operation mode in the present embodiment, power generation can be started in a short time in response to a restart command. Such in-furnace combustion gas supply amount controls the flow rate according to the load of the SOFC 10, thereby adjusting the heat generation amount and maintaining the internal temperature of the power generation chamber 13 within a predetermined range.

  Further, in the hot standby operation mode, the SOFC 10 shifts to a standby state in which power generation is stopped by turning off an inverter (not shown) when the load factor is reduced to a predetermined set value (for example, 2%). Also good. Even when this standby state is reached, the power generation chamber temperature is maintained at a predetermined temperature or higher (400 ° C. or higher) by ventilation of compressed air at 400 to 450 ° C. or combustion in the furnace in the power generation chamber.

FIG. 5 is a flowchart showing a control example for reaching a low load state in the above-described hot standby operation mode.
In the first step S1, the combined power generation system 1 performs a normal operation in which combined power generation is performed by a combined operation in which the SOFC 10 and the MGT 50 are used together. When the SOFC 10 is stopped due to a decrease in power demand from such normal operation, in the next step S2, the operation of the MGT 50 continues and power generation by the SOFC 10 stops, but the SOFC 10 can be restarted quickly. A hot standby command is issued to maintain the standby state. This hot standby command is a command for executing a hot standby operation mode in which a predetermined hot standby state is maintained until the operation of the SOFC 10 is resumed while a transition is made to a hot standby state in which the inside of the power generation chamber 13 of the SOFC 10 is maintained at a predetermined temperature. is there.

When the above-described hot standby command is output, the steam line start-up command in step S3, the first-stage power generation load lowering command in step S5, and the in-furnace combustion start command in step S7 are executed in parallel. Is done.
The steam line start-up instruction in step S3 is an operation for enabling the supply of water vapor in order to supply water vapor from the water vapor supply line 26 to the fuel supply system 20. When the operation enables supply of water vapor, the process proceeds to step S4, and the completion of the steam line start-up is output.

The first-stage power generation load reduction command in step S5 is reduced at the load change rate C1 (A / h) to L1% set as the first-stage load. Note that the load factor L1% in the first stage is, for example, 10% or more, which is a load higher than the lowest load (less than 9%) of the SOFC 10. Further, the load change rate C1 in the first-stage power generation load reduction command is selected in the range of 10 (A / h) to 50 (A / h) in accordance with the load command from the system.
If the module current is within a predetermined range, water vapor (H ₂ O) generated by the power generation reaction is sufficiently contained in the exhaust fuel gas to be recirculated, and is supplied from the city gas supply line 22. City gas can be reformed and the fuel electrode can be kept in a reducing atmosphere.

  The in-furnace fuel start command in step S7 proceeds to the in-furnace combustion city gas supply in step S8 in order to compensate for a decrease in the load factor of the SOFC 10 due to the power generation load reduction command and a decrease in internal heat generation due to power generation. As a result, city gas is supplied from the oxidizing gas supply system 70 into the power generation chamber 13 to cause combustion in the furnace, thereby suppressing a rapid decrease in temperature and contributing to maintaining the temperature of the power generation chamber 13.

Next, in the state where the load has reached the load factor L1% which is the set value of the first stage, when the operation of step S4 and step S6 is completed and the AND condition is satisfied, the process proceeds to step S9 and steam supply to the SOFC 10 is performed. Start.
At the same time, in step S10, the second stage power generation load reduction is performed to L2%, which is a set value of the lowest load factor lower than the first stage load factor L1%. Note that L2% of the minimum load factor is a value of about 2%, for example.

When the load reduction to the minimum load factor L2% is completed in this way, the process proceeds to the next step S11 to perform load interruption. The load interruption in step S11 is a step in which power generation in the SOFC is stopped by turning off inverter control in a state where the SOFC is at the minimum load. As a result, power generation by the SOFC 10 ends, and single power generation by the MGT 50 is performed. Further, the steam supply during this time is continued even after the load and temperature state of the cell stack 12 are detected and the load is shut off in order to maintain the fuel electrode side of the SOFC 10 in a reducing atmosphere.
As a result of the load interruption in step S11, the SOFC reaches the standby state in step S12.

In the present embodiment, the hot standby operation mode described above is performed from the hot standby command in step S2 to the standby state in step S12, and until the next SOFC activation command is output. In order to maintain the temperature t ° C. or higher set as the internal temperature of the power generation chamber 13, the in-furnace combustion started from step S8 is continued.
The set temperature t ° C. in this case is, for example, a value of 400 ° C. or more, and the heat generation amount in the furnace 13 and the high-temperature compressed air supplied from the MGT 50 are heat-exchanged in the SOFC 10 to thereby generate heat in the power generation chamber 13. The temperature is maintained.

  In addition, it is desirable that heating by combustion in the furnace in the hot standby operation mode is also used in combination with heating of the fuel supply line by a trace heater. That is, the fuel gas discharge system 27 that connects between the SOFC 10 and the MGT 50, for example, a flow path heating in which a trace heater is applied to the fuel gas discharge system (27a, 27b, 27c) indicated by a broken line in FIG. If it has the part, while it becomes easy to maintain the inside of the power generation chamber 13 at the set temperature t ° C. or more, it is easy to maintain the temperature of the fuel gas supplied to the MGT 50 at the set temperature t ° C. or more. Become.

  In the first embodiment described above, in-furnace combustion is employed in which the city gas injected to the air electrode side of the power generation chamber 13 is used as the heating unit. However, the second embodiment described with reference to FIGS. As described above, a method of heating by catalytic combustion may be employed. In addition, in 2nd Embodiment demonstrated below, the same code | symbol is attached | subjected to the part similar to 1st Embodiment mentioned above, and the detailed description is abbreviate | omitted.

  In the combined power generation system 1 ′ according to the second embodiment, the catalytic combustion heating unit supplies fuel to the catalytic combustor 80 installed in the flow path 70 that supplies compressed air from the MGT 50 to the air electrode side of the power generation chamber 13. The city gas is supplied and burned, and the compressed air is heated to raise the temperature to a desired temperature, and then supplied to the air station side of the power generation chamber 13. That is, in the system diagram shown in FIG. 6, the structure in which the catalytic combustor 80 is installed in the flow path of the oxidizing gas supply system 70 is different. In the flowchart shown in FIG. The catalytic combustion start command of 'is different from the above-described in-furnace combustion start command of Step S7 and Step S8.

In this method, since the temperature of the compressed air supplied from the MGT 50 is as high as about 400 to 450 ° C., an operation in a hot standby state with a small fuel consumption required for heating can be realized. That is, if the high-temperature compressed air supplied from the MGT 50 is used and the supply amount and supply temperature of the compressed air are appropriately adjusted according to the internal temperature of the power generation chamber 13, the inside of the power generation chamber 13 is heated with the compressed air. It becomes possible to maintain the internal temperature within a predetermined range.
In this embodiment as well, heating of the fuel supply line by a trace heater may be used in combination.

In other words, in this embodiment, while maintaining the combined operation state of the SOFC 10 and the MGT 50 in the hot standby operation mode, the supply of high-temperature compressed air by the compressor 51 of the MGT 50 is maintained, and the oxidizing gas supply system 70 is maintained. By supplying the city gas to the catalytic combustor 80 installed in, heating with compressed air is performed to maintain the internal temperature of the power generation chamber 13 at or above the set temperature t ° C. At this time, the load of the MGT 50 is not controlled to follow the load of the SOFC 10, and is independently controlled by directly injecting the city gas of fuel into the combustor 52 of the MGT 50.
In this case, part of the compressed air may bypass the SOFC 10 and be input to the combustor 52 of the MGT 50.

  As described above, according to the above-described first and second embodiments, the temporarily stopped SOFC 10 is maintained at a predetermined pressure in the pressure vessel in which the SOFC cartridge 11 is housed. Is maintained at a high temperature that is equal to or higher than the power generation start temperature, and thus is maintained in a restart standby state. For this reason, in the SOFC 10 that is a high-temperature fuel cell, the time required to raise the temperature to the power generation start temperature is unnecessary, and the time required for restarting can be shortened by this amount.

  In the first and second embodiments described above, the SOFC 10 and the MGT 50 are combined to generate power, and when the MGT 50 is operated, the SOFC 10 is temporarily stopped to enter a standby state. In the combined power generation system 1, 1 ′ having the operation mode for shifting to the hot standby state maintained at the temperature, the temperature in the hot standby state is maintained at the time of transition to the hot standby state by temperature adjustment for heating the inside of the power generation chamber 13. The driving method to be performed becomes possible.

  In such an operation method, the temperature in the hot standby state is maintained and the temperature in the hot standby state is maintained by temperature adjustment in which the inside of the power generation chamber 13 is heated by the combustion gas combusted by combustion or the temperature-adjusted compressed air. Therefore, in the power generation chamber 13 of the SOFC 10 that has been temporarily stopped, it is possible to compensate for the decrease in the amount of self-heating by adjusting the temperature for heating the inside of the power generation chamber 13. Therefore, the time required for restarting the SOFC 10 can be shortened by performing the operation in the hot standby state in which the inside of the power generation chamber 13 is maintained at a desired temperature.

As described above, according to the above-described embodiment, the temperature, the load factor, and the air flow rate are controlled by the control device while maintaining the combined operation, and the supply air amount and the nitrogen flow rate are linked to the load. Thus, since the start / stop operation can be performed continuously, the system can shorten the time until hot standby. Moreover, it becomes a system which improves the durability of SOFC10 with respect to frequent repetition of starting and stopping.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.

1 Combined power generation system (fuel cell / gas turbine power generation system)
10 SOFC (solid oxide fuel cell)
DESCRIPTION OF SYMBOLS 11 SOFC cartridge 12 Cell stack 13 Power generation chamber 14 Fuel gas supply chamber 15 Fuel gas discharge chamber 16 Oxidizing gas supply chamber 17 Oxidizing gas discharge chamber 20 Fuel supply system 21, 23, 25 On-off valve 22 City gas (fuel) supply line 24 Nitrogen gas supply line 26 Water vapor supply line 27 Fuel gas discharge system 50 MGT (micro gas turbine)
51 Compressor 52 Combustor 53 Turbine 60 Chimney 70 Oxidizing Gas Supply System 80 Catalytic Combustor

Claims (7)

A combined power generation system having an operation mode in which a fuel cell and an internal combustion engine are combined to generate power, and the fuel cell is shifted to a standby state when the fuel cell is stopped while the internal combustion engine is in operation.
Examples for temperature maintenance during the transition and the standby state to the standby state, the heating unit is provided for raising the temperature of the temperature of the power generation chamber,
In the operation mode, when a stop command for the fuel cell is output, a first step of reducing the load to the load factor of the first stage of the fuel cell and a first step of reducing the load to the load factor of the second stage. 2 is executed, and the second step is executed after reaching the load factor set by the first step, and when the first step is executed, the fuel cell is placed in the furnace. A combined power generation system characterized by executing a third step of charging combustion gas .   2. The combined power generation system according to claim 1, wherein the heating unit is in-furnace combustion that generates heat by oxidizing fuel input to the air electrode side of the power generation chamber.   2. The catalytic combustion, wherein the heating unit is a catalytic combustion in which fuel is injected into a catalytic combustor installed in a flow path for supplying compressed air from the internal combustion engine to the air electrode side of the power generation chamber. The combined power generation system according to 1.   The combined power generation system according to claim 2 or 3, wherein a fuel flow path connecting between the fuel cell and the internal combustion engine includes a flow path heating unit. 5. The composite according to claim 1, wherein, in the operation mode, when the second step is executed, a fourth step of supplying water vapor to the fuel cell is executed. Power generation system. A method for operating a combined power generation system comprising an operation mode in which a fuel cell and an internal combustion engine are combined to generate power and the fuel cell is stopped in a state where the internal combustion engine is operated,
In the operation mode, when a stop command for the fuel cell is output, a first step of reducing the load to the load factor of the first stage of the fuel cell and a first step of reducing the load to the load factor of the second stage. 2 steps and
The second step is executed after reaching the load factor set by the first step,
When the first step is executed, a third step of introducing a combustion gas in the furnace into the fuel cell is executed. The method of operating a combined power generation system according to claim 6 , wherein when the second step is executed, a fourth step of supplying water vapor to the fuel cell is executed.

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