JP4508660B2 - Combined power generation system using high-temperature fuel cell - Google Patents

Description

  The present invention relates to a combined power generation system using a high-temperature fuel cell that is combined with power generation using a high-temperature fuel cell and power generation using a gas turbine and is controlled to operate at a normal pressure.

A fuel cell generates electricity by directly converting chemical energy of fuel into electric energy. This 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 side, and an electrolyte that passes only ions between them, and there are various types depending on the type of electrolyte. Has been developed.
Among these, solid oxide fuel cells (hereinafter referred to as “SOFC”) use ceramics such as zirconia ceramics as an electrolyte, and use natural gas, petroleum, methanol, coal gasification gas, etc. as fuel. A fuel cell to be operated. This SOFC has a high operating temperature of about 900 to 1000 ° C. in order to increase the ionic conductivity, and is known as a high-efficiency high-temperature fuel cell that is versatile. This SOFC can use a common fuel, and since it operates at a high temperature, it is compatible with a gas turbine that can utilize the exhaust heat of the SOFC. A combined power generation system that combines a SOFC and a gas turbine, that is, a high-temperature type A combined power generation system using a fuel cell (hereinafter referred to as “SOFC combined power generation system”) is expected as a power generation system capable of achieving high efficiency.

  The above-described SOFC needs to flow the fuel gas and air into the battery system at a high temperature. However, in the conventional SOFC combined power generation system, as described in, for example, Patent Document 1, high-pressure air compressed by a gas turbine compressor is introduced into the SOFC air electrode to generate power, and then the reaction during power generation Since it is configured to reuse the heat generated by burning the unreacted fuel gas and air in the heat to drive the gas turbine, the battery system uses high-temperature fuel gas and air in addition to high temperatures. It is a pressurized SOFC that flows inside.

  In this conventional pressurized SOFC combined power generation system, the high pressure air compressed by the compressor of the gas turbine is introduced into the air electrode by the combination of the SOFC and the gas turbine. It was necessary to make it SOFC. Such a pressurized SOFC requires a fuel electrode, an air electrode, and an electrolyte to be installed in the pressure vessel, and also requires a compressor that pressurizes the fuel and supplies it to the fuel electrode. There was an inconvenience that the cost was higher than the SOFC that can be operated.

  In addition, the gas turbine has a good startability, and has an advantage that power generation can be started by performing rated operation within a short time from the start of operation. On the other hand, since SOFC uses ceramics as the electrolyte, problems such as cracking occur when the operating temperature is suddenly raised, so the startability is not good. In particular, since the air compressed by the compressor of the gas turbine is introduced into the SOFC, the operation of the gas turbine is indispensable for generating power with the SOFC. When the gas turbine is started, air whose temperature has been increased by compression is supplied and passes through the SOFC, so that the ceramics of the electrolyte are heated and heated in a relatively short time. For this reason, in the SOFC combined power generation system, it is necessary to gradually increase the operation speed of the gas turbine. As a result, the startability of the gas turbine cannot be effectively used, and the startability of the entire system is not good. There was an inconvenience.

For this reason, for example, Patent Document 2 proposes a combined power generation system using a high-temperature fuel cell that can be operated at normal pressure. This normal pressure SOFC combined power generation system is capable of operating a fuel cell at normal pressure by introducing gas turbine exhaust containing a sufficient amount of oxygen discharged from the gas turbine into the air electrode of a high temperature fuel cell. It is. Further, in this atmospheric pressure type SOFC combined power generation system, it is possible to efficiently generate power by effectively utilizing the exhaust heat of the gas turbine or the high temperature fuel cell by heat exchange.
Japanese Patent Laying-Open No. 2002-289889 (see FIG. 1) JP 2003-217602 A (see FIG. 1)

  However, the following problems remain in the conventional SOFC combined power generation system. That is, in the conventional atmospheric pressure type SOFC combined power generation system, there are still operational restrictions for protecting the equipment due to the difference in the starting characteristics and load followability between the gas turbine and the fuel cell. For example, due to the difference in characteristics, it is difficult to control the gas turbine inlet temperature, the SOFC stack inlet temperature, and the SOFC inter-electrode differential pressure. In addition, when the power supply is lost, the necessary power is not supplied in the power plant, and it is difficult to operate the power plant alone.

  The present invention has been made in view of the above-described problems, and provides a combined power generation system using a high-temperature fuel cell that can be operated and controlled in compliance with operation restrictions for equipment protection even in a normal pressure type. Objective.

The present invention employs the following configuration in order to solve the above problems. That is, the combined power generation system using the high-temperature fuel cell of the present invention includes a high-temperature fuel cell that generates electric power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure, and a compressor unit and a turbine unit that are coaxially connected. A gas turbine having a power generator that generates power by being driven by the output of the gas turbine, a compressed air supply passage that introduces gas turbine compressed air supplied from the compressor section to the turbine section, and is discharged from the gas turbine A gas turbine exhaust supply passage that supplies gas turbine exhaust as high-temperature fuel cell high-temperature air to the air electrode of the high-temperature fuel cell, and an unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell and the air electrode and the unreacted fuel combustor for introducing a portion of the gas turbine exhaust is fed directly from the unreacted air and gas turbine combustion, and is discharged from the unreacted fuel combustor Characterized in that it comprises a heat exchanger to raise the temperature of the gas turbine compressor air in the heat exchanger by tempering device exhaust, and adjustable exhaust gas temperature control means the temperature of the combustor exhaust.

  In this combined power generation system, the temperature of the gas turbine compressed air can be adjusted by the heat exchanger by adjusting the temperature of the combustor exhaust by the exhaust temperature control means when the turbine inlet temperature is different from the target. Independently, the turbine inlet temperature can be controlled to a target value. In particular, the turbine inlet temperature can be stably controlled by operating the exhaust temperature control means in advance according to the change in the operating state of the SOFC.

Further, in the combined power generation system using the high temperature fuel cell of the present invention, the exhaust temperature control means supplies the auxiliary fuel to the unreacted fuel combustor by variably controlling the mixing ratio of the auxiliary fuel together with the unreacted fuel gas. It is provided with a mechanism.
That is, in this combined power generation system, the auxiliary fuel supply mechanism variably controls the mixing ratio of the auxiliary fuel together with the unreacted fuel gas and supplies it to the unreacted fuel combustor, thereby adjusting the combustor exhaust temperature and exchanging heat. Since the temperature of the gas turbine compressed air can also be adjusted by the generator, the turbine inlet temperature can be controlled to a target value. Moreover, in this system, since the unreacted fuel combustor is in the low pressure portion of the gas turbine exhaust, fuel can be supplied at a lower pressure than in the pressurized system.

Further, in the combined power generation system using the high-temperature fuel cell of the present invention, the exhaust temperature control means pressurizes and supplies at least a part of the combustor exhaust with a variable pressure to the unreacted fuel combustor. An air supply mechanism is provided, and the combustor exhaust heats the gas turbine compressed air by heat exchange by the combustor exhaust, and the exhaust heat of the combustor exhaust downstream from the high temperature regeneration heat exchanger. It has passed through the fuel recirculation flow path provided with the exhaust heat recovery boiler to collect | recover . It is characterized by the above-mentioned.
That is, in this combined power generation system, a part of the low-temperature combustor exhaust at the exhaust heat recovery boiler outlet is pressurized and supplied to the unreacted fuel combustor by variably controlling the pressure by the pressurized air supply mechanism. Since the temperature of the gas turbine compressed air can be adjusted by the heat exchanger by adjusting the combustor exhaust temperature, the turbine inlet temperature can be controlled to the target value.

A combined power generation system using a high-temperature fuel cell according to the present invention includes a high-temperature fuel cell that generates electric power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure, and a compressor unit and a turbine unit that are connected coaxially. A gas turbine, a generator driven by the output of the gas turbine to generate electric power, a compressed air supply passage for introducing gas turbine compressed air supplied from the compressor section into the turbine section, and a gas turbine discharged from the gas turbine A gas turbine exhaust supply passage that supplies exhaust gas as high-temperature fuel cell high-temperature air to the air electrode of the high-temperature fuel cell, and unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell and unreacted gas that has passed through the air electrode and the unreacted fuel combustor for introducing a portion of the gas turbine exhaust is fed directly from the air and the gas turbine combustor, the combustor exhaust gas discharged from the unreacted fuel combustor And a stack inlet temperature control means for variably controlling the temperature of at least one of a heat exchanger for raising the temperature of the gas turbine compressed air by heat exchange and a main fuel gas supplied to the fuel electrode and a gas turbine exhaust supplied to the air electrode. It is characterized by having.

  In this combined power generation system, the stack inlet temperature control means variably controls the temperature of at least one of the main fuel gas supplied to the fuel electrode and the gas turbine exhaust supplied to the air electrode, so that the fuel electrode and the air electrode At least one of the temperatures can be adjusted, and the stack inlet temperature can be controlled independently of the operating state of the gas turbine.

Further, in the combined power generation system using the high temperature fuel cell of the present invention, the stack inlet temperature control means burns part of the unreacted fuel gas and the start-up air, and controls the temperature of the main fuel gas by the combustion exhaust gas. A fuel-side start-up combustor is provided.
That is, in this combined power generation system, the fuel-side start-up combustor burns part of the unreacted fuel gas and start-up air, and controls the temperature of the main fuel gas with the combustion exhaust gas. The fuel side temperature at the stack inlet can be controlled using the combustion heat with the working air.

Further, in the combined power generation system using the high-temperature fuel cell of the present invention, the stack side inlet temperature control means is provided in the gas turbine exhaust supply flow path, and combusts the gas turbine exhaust and the starting fuel. It is characterized by having.
That is, in this combined power generation system, when the temperature of the gas turbine exhaust is low, the gas turbine exhaust is heated by burning the gas turbine exhaust and the starting fuel by the air-side starting combustor, and the gas turbine exhaust The air temperature at the stack inlet can be adjusted independently of the operating state. In addition, it becomes possible to control the temperature difference at the inlet of the stack more easily by combining the fuel-side start-up combustor.

Further, in the combined power generation system using the high-temperature fuel cell of the present invention, the stack inlet temperature control means includes a bypass channel provided via a bypass valve in the middle of the gas turbine exhaust supply channel, and a bypass channel. And a cooler for cooling the gas turbine exhaust.
That is, in this combined power generation system, at the initial stage of starting the high-temperature fuel cell, a part of the high-temperature gas turbine exhaust is not supplied directly to the fuel cell but supplied to the cooler to be cooled and mixed with the bypass side fluid. By doing so, the air side temperature of the stack inlet can be adjusted independently of the operating state of the gas turbine. In addition, it becomes possible to control the temperature difference at the inlet of the stack more easily by combining the fuel-side start-up combustor.

A combined power generation system using a high-temperature fuel cell according to the present invention includes a high-temperature fuel cell that generates electric power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure, and a compressor unit and a turbine unit that are connected coaxially. A gas turbine, a generator driven by the output of the gas turbine to generate electric power, a compressed air supply passage for introducing gas turbine compressed air supplied from the compressor section into the turbine section, and a gas turbine discharged from the gas turbine A gas turbine exhaust supply passage that supplies exhaust gas as high-temperature fuel cell high-temperature air to the air electrode of the high-temperature fuel cell, and unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell and unreacted gas that has passed through the air electrode and the unreacted fuel combustor for introducing a portion of the gas turbine exhaust is fed directly from the air and the gas turbine combustor, the combustor exhaust gas discharged from the unreacted fuel combustor And a stack inlet pressure control means for variably controlling the flow rate of at least one of the heat exchanger for raising the temperature of the gas turbine compressed air by heat exchange and the main fuel gas supplied to the fuel electrode and the gas turbine exhaust supplied to the air electrode. It is characterized by having.

  In this combined power generation system, the stack inlet pressure control means variably controls the flow rate of at least one of the main fuel gas supplied to the fuel electrode and the gas turbine exhaust supplied to the air electrode to The pressure difference between the fuel side and the air side at the stack inlet can be controlled independently.

In the combined power generation system using the high-temperature fuel cell according to the present invention, the stack inlet pressure control means includes a main fuel supply channel for supplying the main fuel gas to the fuel electrode, and a part of the unreacted fuel gas as the main fuel. A fuel recirculation flow path that returns to the supply flow path, and a fuel flow rate control means that is provided in the fuel recirculation flow path and variably controls the flow rate of the unreacted fuel gas to be supplied to the main fuel supply flow path. Features.
That is, in this combined power generation system, the flow rate of unreacted fuel gas is variably controlled by the fuel flow rate control means and supplied to the main fuel supply flow path, thereby controlling the flow rate of fuel flowing into the stack and operating the gas turbine. Independent of the situation, the pressure difference between the poles at the stack inlet can be controlled. Further, even when the pressure of the gas turbine exhaust in the normal pressure system is low, the fuel can be circulated and the power consumption can be reduced.

In the combined power generation system using the high-temperature fuel cell according to the present invention, the stack inlet pressure control means includes an exhaust flow rate control means for controlling the flow rate of the gas turbine exhaust provided in the gas turbine exhaust supply passage. It is characterized by.
That is, in this combined power generation system, the flow rate of air flowing into the stack is controlled by controlling the branch flow rate from the gas turbine exhaust by the exhaust flow rate control means, and the influence on the SOFC due to the change in the operating condition of the gas turbine is controlled. The operation can be reduced as much as possible, and the pressure difference between the electrodes at the stack inlet can be controlled.

Furthermore, in the combined power generation system using the high-temperature fuel cell of the present invention, the exhaust flow rate control means includes a main air flow rate control mechanism that supplies main air to the compressor unit by controlling the flow rate. It is preferable to control the branch flow rate of the gas turbine exhaust according to the flow rate control of the main air.
That is, in this combined power generation system, the main air flow rate and the gas turbine exhaust flow rate are cooperatively operated in advance by controlling the flow rate of the gas turbine exhaust according to the main air flow rate control by the main air flow rate control mechanism. Can do.

The combined power generation system using the high temperature fuel cell according to the present invention includes a fuel cell side power line connected to the power system for transmitting power from the high temperature fuel cell, and a power connected to the power system from the generator. At least one system operation power line can be connected to the generator side power line to transmit power, the system operation power line that supplies power into the power generation system, and the power system of the fuel cell side power line and the generator side power line. And a power switching means capable of switching connection.
That is, in this combined power generation system, even in the event of power loss such as a power failure, the power switching means can arbitrarily connect at least one system power line to the power system of the fuel cell side power line and the generator side power line. By switching to and connected, the necessary power is supplied in the power plant, so that the single operation in the power plant (power generation system) becomes possible, and the operating rate of the system can be improved.

The present invention has the following effects.
That is, according to the combined power generation system using the high-temperature fuel cell according to the present invention, the temperature of the gas turbine compressed air can be adjusted by the exhaust temperature control means, so that the turbine inlet temperature can be targeted independently of the operating state of the SOFC. The value can be controlled.
Further, according to the present invention, the stack inlet temperature control means can adjust the temperature of at least one of the fuel electrode and the air electrode, and the stack inlet temperature can be controlled independently of the operating state of the gas turbine.
Further, according to the present invention, the stack inlet pressure control means can adjust the inlet flow rate of at least one of the fuel electrode and the air electrode, and the fuel side and air side of the stack inlet can be adjusted independently of the operation status of the gas turbine. The pressure difference can be controlled.
As described above, according to the present invention, in the atmospheric pressure type SOFC combined power generation system, the other side can be controlled independently of the operating state of one of the SOFC and the gas turbine, and the operation complying with the operation restrictions for equipment protection can be performed.

  Hereinafter, a first embodiment of a combined power generation system using a high-temperature fuel cell according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the combined power generation system of this embodiment includes a high-temperature fuel cell (SOFC) 1 that generates power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure, and a compressor unit that is coaxially connected. 2 and a gas turbine 4 having a turbine section 3, a generator 5 driven by the output of the gas turbine 4 to generate power, and a compressed air supply for introducing gas turbine compressed air supplied from the compressor section 2 into the turbine section 3. And a flow path 6. That is, this combined power generation system is configured to obtain high power generation efficiency by combining power generation by the SOFC 1 and power generation by the gas turbine 4.

  The power generation by the SOFC 1 is generated by the reaction of high-temperature fuel gas and high-temperature air that are heated and supplied so that the operating temperature is about 1000 ° C., for example. Power generation by the gas turbine 4 is performed by operating the generator 5 connected coaxially with the output of the gas turbine 4 as a drive source. In the gas turbine 4, the main air is compressed air in the compressor unit 2, the compressed air introduced through the compressed air supply passage 6 and the gas turbine fuel are combusted, and the combustion gas is expanded to expand the turbine unit 3. The generator 5 is operated by rotating. In addition, as a gas turbine fuel, the same thing as the fuel of SOFC1, such as natural gas, can be used, for example.

  The combined power generation system also includes a gas turbine exhaust supply passage 7 that supplies gas turbine exhaust discharged from the gas turbine 4 to the air electrode 1A of the SOFC 1 as high-temperature air of the SOFC 1, and a fuel turbine 1B that has not passed through the fuel electrode 1B of the SOFC 1. An unreacted fuel gas flow path 8 for flowing the reactive fuel gas, an unreacted air flow path 9 for flowing unreacted air that has passed through the air electrode 1A, an unreacted fuel gas flow path 8 and an unreacted air flow path 9; An unreacted fuel combustor 11 connected to the branch flow path 10 from the gas turbine exhaust supply flow path 7 to introduce and burn unreacted fuel gas, unreacted air, and part of the gas turbine exhaust; and unreacted fuel combustion A combustor exhaust passage 12 for exhausting the combustor exhaust discharged from the combustor 11 to the chimney, and a gas cylinder provided in the middle of the combustor exhaust passage 12 and the compressed air supply passage 6 by the combustor exhaust. The bottle compressed air and a high temperature heat exchanger 13 to a temperature rise in the heat exchanger. The air electrode 1A and the fuel electrode 1B constitute a stack in which single cells are stacked.

Furthermore, the combined power generation system of the present embodiment includes an auxiliary fuel supply mechanism (exhaust temperature control means) 14 that supplies auxiliary fuel to the unreacted fuel combustor 11 by variably controlling the mixing ratio of the auxiliary fuel together with the unreacted fuel gas, and at least A pressurized air supply mechanism (exhaust temperature control means) 15 is provided to supply pressure to a non-reacted fuel combustor 11 by variably controlling the pressure of some combustor exhaust.
The auxiliary fuel supply mechanism 14 includes an auxiliary fuel channel 16 connected in the middle of the unreacted fuel gas channel 8 and an auxiliary fuel control valve 17 provided in the auxiliary fuel channel 16.

Connected to the compressor section 2 is a main air control valve (main air flow rate control mechanism) 18 that supplies main air by controlling its flow rate.
In the middle of the gas turbine exhaust supply flow path 7 and the compressed air supply flow path 6, low-temperature regenerative heat exchange is performed to heat the gas turbine compressed air to a desired temperature by exchanging heat between the gas turbine exhaust and the gas turbine compressed air. A container 19 is provided. An air preheater 20 is provided in the middle of the gas turbine exhaust supply passage 7 and the unreacted air passage 9 to heat the gas turbine exhaust to a desired temperature by exchanging heat between the gas turbine exhaust and the unreacted air. It has been.

The combustor exhaust passage 12 is provided with an exhaust heat recovery boiler 21 that recovers exhaust heat of the combustor exhaust downstream of the high temperature regeneration heat exchanger 13. In the exhaust heat recovery boiler 21, exhaust heat can be used by supplying steam or hot water obtained by heat exchange with exhaust heat.
The pressurized air supply mechanism 15 branches from the exhaust heat recovery boiler 21 in the combustor exhaust passage 12 downstream from the downstream, and in the middle of the unreacted fuel gas passage 8 (downstream from the branch portion of the fuel recirculation passage 22). From an air recirculation flow path 23 to be connected, and an air recirculation fan 24 provided in the air recirculation flow path 23 to supply pressure to the unreacted fuel gas flow path 8 while variably controlling the pressure of the combustor exhaust. It is configured.

A main fuel gas passage 25 is connected to the inlet of the fuel electrode 1B, and a main fuel gas control valve 26 that variably controls the flow rate of the main fuel gas is provided in the main fuel gas passage 25.
In the middle of the unreacted fuel gas flow path 8 and the main fuel gas flow path 25, a fuel preheater 27 for exchanging heat between the unreacted fuel gas and the main fuel gas and heating the main fuel gas to a desired temperature is provided. Is provided.
A fuel recirculation flow path 22 having a fuel recirculation fan (fuel flow rate control means, stack inlet pressure control means) 28 is branched from the unreacted fuel gas flow path 8 and connected to the main fuel gas flow path 25. ing. That is, a part of the unreacted fuel gas is returned to the main fuel gas passage 25 via the fuel recirculation passage 22 by the fuel recirculation fan 28.

  Although not shown, the combined power generation system of the present embodiment includes a fuel cell side power line that is connected to the power system and transmits power from the SOFC 1, and a generator that is connected to the power system and transmits power from the generator 5. A side power line and a system operation power line for supplying power into the power generation system.

  Next, the operation method of the combined power generation system of this embodiment will be described.

First, main air is introduced into the compressor unit 2 via the main air control valve 18 to form compressed air, and then the compressed gas is used as the low-temperature regeneration heat exchanger 19 and the high-temperature regeneration heat exchanger 13 in the compressed air supply passage 6. Is heated and burned with gas turbine fuel, and the turbine unit 3 is rotated by this combustion gas to operate the generator 5.
The gas turbine exhaust discharged from the turbine section 3 is a high-temperature gas fluid that has expanded to atmospheric pressure, and contains a sufficient amount of oxygen necessary to react with the high-temperature main fuel gas in the SOFC 1. . The gas turbine exhaust is heated by the air preheater 20 and then introduced into the air electrode 1A of the SOFC 1. On the other hand, the main fuel gas is introduced into the main fuel gas passage 25 through the main fuel gas control valve 26, heated by the fuel preheater 27, and then introduced into the fuel electrode 1B. In the SOFC 1, power generation is performed by a reaction between the gas turbine exhaust of the air electrode 1A and the main fuel gas of the fuel electrode 1B. The electric power generated by the power generation by the generator 5 and the SOFC 1 is transmitted to the power system.

  Unreacted air exiting from the air electrode 1 </ b> A is supplied to the unreacted fuel combustor 11 together with gas turbine exhaust from the branch flow path 10. On the other hand, the unreacted fuel gas emitted from the fuel electrode 1B is supplied to the unreacted fuel combustor 11 together with the auxiliary fuel from the auxiliary fuel flow path 16 whose flow rate is controlled by the auxiliary fuel control valve 17. As a result, unreacted air and gas turbine exhaust, unreacted fuel gas and auxiliary fuel react and burn in the unreacted fuel combustor 11, and high-temperature combustor exhaust is supplied to the combustor exhaust passage 12. This combustor exhaust is exhausted from the chimney via the high-temperature regenerative heat exchanger 13 and the exhaust heat recovery boiler 21, but a part of the combustor exhaust is controlled by the air recirculation fan 24 through the air recirculation flow path 23 and is again unrecovered The reaction fuel combustor 11 is introduced together with the unreacted fuel gas and the like.

  Here, for example, when the turbine inlet temperature is lower than the target, the auxiliary fuel supply mechanism 14 increases the auxiliary fuel mixing ratio or the pressurized air supply mechanism 15 decreases the combustor exhaust flow rate (decreases the inverter value). Thus, the temperature of the combustor exhaust is raised to control the turbine inlet temperature to the target value. In particular, the turbine inlet temperature can be stably controlled by operating these mechanisms in advance according to changes in the operating state of the SOFC 1.

That is, in this embodiment, the auxiliary fuel supply mechanism 14 variably controls the mixing ratio of the auxiliary fuel together with the unreacted fuel gas and supplies it to the unreacted fuel combustor 11, thereby adjusting the combustor exhaust temperature and increasing the temperature. The temperature of the gas turbine compressed air can also be adjusted by the regenerative heat exchanger 13. In this system, since the unreacted fuel combustor 11 is in the low pressure portion of the gas turbine exhaust, fuel can be supplied at a lower pressure than in the pressurized system.
Further, a part of the combustor exhaust is variably controlled by the pressurized air supply mechanism 15 and supplied to the unreacted fuel combustor 11 under pressure, thereby adjusting the combustor exhaust temperature and the high temperature regenerative heat exchanger. 13 can adjust the temperature of the gas turbine compressed air. Therefore, when the turbine inlet temperature is different from the target, the temperature of the combustor exhaust is adjusted by the auxiliary fuel supply mechanism 14 or the pressurized air supply mechanism 15, so that the turbine inlet temperature is targeted independently of the operating state of the SOFC 1. The value can be controlled.

  Next, a second embodiment and a third embodiment of a combined power generation system using a high-temperature fuel cell according to the present invention will be described with reference to FIGS. In the following description, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that, in the second embodiment, as shown in FIG. 2, a part of the unreacted fuel gas and the start-up air are burned and the main fuel gas is discharged by combustion. A fuel side starting combustor (stack inlet temperature control means) 30 for controlling the temperature of the fuel is provided in the fuel recirculation flow path 22. In other words, in the present embodiment, an activation air flow path 32 that is connected to the fuel-side activation combustor 30 and supplies the activation air with the activation air control valve 31 variably controlling the flow rate is provided. As a result, the starting air control valve 31 variably controls the flow rate of the starting air, thereby adjusting the combustion of the unreacted fuel gas from the fuel side starting combustor 30 and controlling the combustion exhaust temperature to control the main fuel. It can be introduced into the gas flow path 25. Therefore, the main fuel gas temperature in the main fuel gas channel 25 can be controlled, and the fuel side temperature at the stack inlet can be controlled.

  The difference between the third embodiment and the second embodiment is that, in the third embodiment, as shown in FIG. 3, the air-side startup combustor 33 that combusts the gas turbine exhaust and the startup fuel is a gas turbine exhaust. This is a point provided in the supply flow path 7. In the combined power generation system according to the third embodiment, the bypass passage 35 provided in the middle of the gas turbine exhaust supply passage 7 via the bypass valve 34 and the gas turbine exhaust provided in the bypass passage 35 are cooled. And a cooler 36. Further, in the combined power generation system of the third embodiment, the stack air flow control valve (exhaust flow control means, stack inlet pressure control means) 37 for variably controlling the flow rate of the gas turbine exhaust supplied to the air electrode 1A is a gas turbine exhaust. It is provided in the supply flow path 7.

  The air side start combustor 33 is provided downstream of the gas turbine exhaust supply flow path 7 where it joins the bypass flow path 35, and is connected to a start fuel flow path 38 for supplying start fuel. The starting fuel flow path 38 is provided with a starting fuel control valve 39 for variably controlling the flow rate of the starting fuel. Therefore, in this embodiment, when the temperature of the gas turbine exhaust is low, the gas turbine exhaust is heated by burning the gas turbine exhaust and the starting fuel by the air-side starting combustor 33, and the gas turbine 4 The air side temperature at the stack inlet can be adjusted independently of the operation state.

  In this embodiment, in the initial stage of starting the high-temperature fuel cell, a part of the high-temperature gas turbine exhaust is supplied to the cooler 36 and cooled and mixed with the bypass fluid 35 so as not to be supplied directly to the SOFC 1. Thus, the air side temperature at the stack inlet can be adjusted independently of the operating state of the gas turbine 4. Note that by controlling the air side start combustor 33 and the cooler 36 in combination with the fuel side start combustor 30, the temperature difference at the stack inlet can be controlled more easily.

  Further, in the present embodiment, the gas supplied to the air electrode 1A by flowing a part of the gas turbine exhaust to the unreacted fuel combustor 11 via the branch flow path 10 by the flow rate control of the stack air flow rate control valve 37. The flow rate of the turbine exhaust can be variably controlled. In this way, by variably controlling the flow rate of the gas turbine exhaust supplied to the air electrode 1A by the stack air flow rate control valve 37, the fuel side and air side of the stack inlet can be controlled independently of the operation status of the gas turbine 4. The pressure difference between the electrodes can be controlled.

  Further, the stack air flow control valve 37 is set to control the flow rate of the gas turbine exhaust according to the main air flow control by the main air control valve 18. That is, in the combined power generation system of the present embodiment, the main air flow rate and the gas turbine exhaust flow rate are coordinated in advance by controlling the flow rate of the gas turbine exhaust according to the flow control of the main air by the main air control valve 18. It can be operated.

  Next, a fourth embodiment and a fifth embodiment of a combined power generation system using a high-temperature fuel cell according to the present invention will be described with reference to FIGS. 4 and 5. In the following description, the same constituent elements described in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the fourth embodiment and the third embodiment is that, in the fourth embodiment, as shown in FIG. 4, a variable fuel recirculation fan (variably controlling the flow rate of the main fuel gas supplied to the fuel electrode 1B) (Fuel flow rate control means, stack inlet pressure control means) 40 is provided in the fuel recirculation flow path 22. That is, in the combined power generation system of the fourth embodiment, the flow rate of the unreacted fuel gas to the fuel-side startup combustor 30 is variably controlled by the variable fuel recirculation fan 40, thereby The flow rate of the main fuel gas in the main fuel gas passage 25 can be variably controlled together with the flow rate of the combustion exhaust gas. Therefore, in the present embodiment, the flow rate of the main fuel gas supplied to the fuel electrode 1B by the variable fuel recirculation fan 40 can be variably controlled, and the fuel side at the stack inlet can be controlled independently of the operation status of the gas turbine 4. The differential pressure between the air side and the air side can be controlled.

  As shown in FIG. 5, the combined power generation system according to the fifth embodiment is connected to the power system L1 that is connected to the power system L1 and transmits power from the SOFC1 via the orthogonal converter 41, and the power system L1. And a generator-side power line L3 for transmitting power from the generator 5 and a system operation power line L4 for supplying power into the power generation system. The difference between the fifth embodiment and the fourth embodiment is that the connection of the fuel cell side power line L2 and the generator side power line L3 with the power system L1 is arbitrarily switched to the system operation power line L4. The power switching means 42 that can be connected is provided.

The system operation power line L4 normally supplies power to these facilities by connecting the power system L1 and power operation facilities (for example, the fuel recirculation fan 28 and the air recirculation fan 24) in the power generation system. A main power transmission line L41 and a sub power transmission line L42 that is not connected to any power line at normal times are provided.
The power switching means 42 is a connection between the first switching switch S1 that can be switched to the sub power transmission line L42 by disconnecting the connection of the fuel cell side power line L2 with the power system L1 and the power transmission system L1 of the main power transmission line L41. A second changeover switch section S2 that can be switched to the sub power transmission line L42, and a third changeover switch section S3 that can be disconnected from the power system L1 of the generator side power line L3 and switched to the sub power transmission line L42. It has.

  That is, in the present embodiment, when the power supply is lost such as during a power failure, the power switching unit 42 operates the first switching switch unit S1, the second switching switch unit S2, and the third switching switch unit S3 to connect the power system L1. Are disconnected, the fuel cell side power line L2, the generator side power line L3, and the sub power transmission line L42 are connected, and the main power transmission line L41 and the sub power transmission line L42 are connected. First, the gas turbine 4 is started and the electric power from the gas turbine 4 is supplied from the main power transmission line L41 to the power operation facility (for example, the fuel recirculation fan 28 and the air recirculation fan 24) via the sub power transmission line L42. . The SOFC 1 can be supplied with power after the start of the gas turbine 4. At that time, the power is also supplied from the main power transmission line L 41 to the power operation facility from the SOFC 1 via the sub power transmission line L 42.

  As described above, in this embodiment, even when the power supply is lost such as during a power failure, the power switching means 42 connects at least one connection between the fuel cell side power line L2 and the generator side power line L3 to the power system L1. By arbitrarily switching and connecting to the power line L4, necessary electric power is supplied in the power plant, so that an independent operation in the power plant (power generation system) is possible, and the operating rate of the system can be improved.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

It is a lineblock diagram showing the combined power generation system using the high temperature type fuel cell of a 1st embodiment concerning the present invention. It is a block diagram which shows the combined electric power generation system using the high temperature type fuel cell of 2nd Embodiment which concerns on this invention. It is a block diagram which shows the combined electric power generation system using the high temperature type fuel cell of 3rd Embodiment which concerns on this invention. It is a block diagram which shows the combined electric power generation system using the high temperature type fuel cell of 4th Embodiment which concerns on this invention. It is a block diagram which shows the combined electric power generation system using the high temperature type fuel cell of 5th Embodiment which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... SOFC (high temperature type fuel cell), 1A ... Air electrode, 1B ... Fuel electrode, 2 ... Compressor part, 3 ... Turbine part, 4 ... Gas turbine, 5 ... Generator, 6 ... Compressed air supply flow path, 7 DESCRIPTION OF SYMBOLS ... Gas turbine exhaust supply flow path, 11 ... Unreacted fuel combustor, 13 ... High temperature regeneration heat exchanger, 14 ... Auxiliary fuel supply mechanism (exhaust temperature control means), 15 ... Pressurized air supply mechanism (exhaust temperature control means) , 18 ... main air control valve (main air flow rate control mechanism), 21 ... exhaust heat recovery boiler, 22 ... fuel recirculation passage, 25 ... main fuel gas passage, 28 ... fuel recirculation fan (fuel flow control means, Stack inlet pressure control means), 30 ... Fuel side start combustor (stack inlet temperature control means), 33 ... Air side start combustor, 34 ... Bypass valve, 35 ... Bypass flow path, 36 ... Cooler, 37 ... Stack air flow control valve (exhaust flow control means, (Tack inlet pressure control means), 40 ... variable fuel recirculation fan (fuel flow control means, stack inlet pressure control means), 42 ... power switching means, L1 ... power system, L2 ... fuel cell side power line, L3 ... generator Side power line, L4 ... system operation power line, L41 ... main power transmission line, L42 ... sub power transmission line, S1 ... first changeover switch part, S2 ... second changeover switch part, S3 ... third changeover switch part

Claims (11)

A high-temperature fuel cell that generates power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure; and
A gas turbine having a compressor section and a turbine section coupled coaxially;
A generator driven by the output of the gas turbine to generate electricity;
A compressed air supply passage for introducing gas turbine compressed air supplied from the compressor section into the turbine section;
A gas turbine exhaust supply passage for supplying the gas turbine exhaust discharged from the gas turbine to the air electrode of the high temperature fuel cell as the high temperature air of the high temperature fuel cell;
Unreacted fuel combustion that introduces and burns unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell, unreacted air that has passed through the air electrode, and part of the gas turbine exhaust that is fed directly from the gas turbine And
A heat exchanger that raises the temperature of the gas turbine compressed air by heat exchange with the combustor exhaust discharged from the unreacted fuel combustor;
An exhaust temperature control means capable of adjusting the temperature of the combustor exhaust,
The high-temperature fuel cell, wherein the exhaust temperature control means includes an auxiliary fuel supply mechanism that variably controls the mixing ratio of auxiliary fuel together with the unreacted fuel gas and supplies the auxiliary fuel to the unreacted fuel combustor. Combined power generation system using The exhaust temperature control means includes a pressurized air supply mechanism that variably controls the pressure of at least a part of the combustor exhaust and pressurizes and supplies the unreacted fuel combustor with pressure .
The combustor exhaust recovers exhaust heat of the combustor exhaust downstream of the high temperature regeneration heat exchanger that raises the temperature of the gas turbine compressed air by heat exchange by the combustor exhaust, and the high temperature regeneration heat exchanger. The combined power generation system using a high-temperature fuel cell according to claim 1, wherein the combined power generation system passes through a fuel recirculation passage provided with an exhaust heat recovery boiler . A high-temperature fuel cell that generates power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure; and
A gas turbine having a compressor section and a turbine section coupled coaxially;
A generator driven by the output of the gas turbine to generate electricity;
A compressed air supply passage for introducing gas turbine compressed air supplied from the compressor section into the turbine section;
A gas turbine exhaust supply passage for supplying the gas turbine exhaust discharged from the gas turbine to the air electrode of the high temperature fuel cell as the high temperature air of the high temperature fuel cell;
Unreacted fuel combustion for introducing and burning unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell, unreacted air that has passed through the air electrode, and part of the gas turbine exhaust that is fed directly from the gas turbine And
A heat exchanger that raises the temperature of the gas turbine compressed air by heat exchange with the combustor exhaust discharged from the unreacted fuel combustor;
And a stack inlet temperature control means for variably controlling the temperature of at least one of the main fuel gas supplied to the fuel electrode and the gas turbine exhaust supplied to the air electrode. Combined power generation system using   The stack inlet temperature control means includes a fuel-side start-up combustor that burns part of the unreacted fuel gas and start-up air and controls the temperature of the main fuel gas with the exhaust of the combustion. A combined power generation system using the high-temperature fuel cell according to claim 3.   5. The stack inlet temperature control means includes an air-side start combustor provided in the gas turbine exhaust supply flow path for burning the gas turbine exhaust and start-up fuel. Combined power generation system using the high-temperature fuel cell described in 1. The stack inlet temperature control means, a bypass flow path provided via a bypass valve in the middle of the gas turbine exhaust supply flow path;
A combined power generation system using a high-temperature fuel cell according to any one of claims 3 to 5, further comprising a cooler that is provided in the bypass passage and cools the gas turbine exhaust. A high-temperature fuel cell that generates power by receiving supply of high-temperature fuel gas and high-temperature air at normal pressure; and
A gas turbine having a compressor section and a turbine section coupled coaxially;
A generator driven by the output of the gas turbine to generate electricity;
A compressed air supply passage for introducing gas turbine compressed air supplied from the compressor section into the turbine section;
A gas turbine exhaust supply passage for supplying the gas turbine exhaust discharged from the gas turbine to the air electrode of the high temperature fuel cell as the high temperature air of the high temperature fuel cell;
Unreacted fuel combustion for introducing and burning unreacted fuel gas that has passed through the fuel electrode of the high-temperature fuel cell, unreacted air that has passed through the air electrode, and part of the gas turbine exhaust that is fed directly from the gas turbine And
A heat exchanger that raises the temperature of the gas turbine compressed air by heat exchange with the combustor exhaust discharged from the unreacted fuel combustor;
And a stack inlet pressure control means for variably controlling the flow rate of at least one of the main fuel gas supplied to the fuel electrode and the gas turbine exhaust supplied to the air electrode. Combined power generation system using A main fuel supply passage for supplying the main fuel gas to the fuel electrode;
A fuel recirculation flow path for returning a part of the unreacted fuel gas to the main fuel supply flow path;
8. A fuel flow rate control means provided in the fuel recirculation flow path and variably controlling the flow rate of the unreacted fuel gas and supplying the flow rate to the main fuel supply flow path. Combined power generation system using high-temperature fuel cells.   The high-temperature type according to claim 7 or 8, wherein the stack inlet pressure control means includes exhaust flow rate control means that is provided in the gas turbine exhaust supply passage and controls the flow rate of the gas turbine exhaust. Combined power generation system using fuel cells.   The exhaust flow rate control means includes a main air flow rate control mechanism that supplies main air to the compressor unit while controlling the flow rate of the gas turbine exhaust according to the flow rate control of the main air by the main air flow rate control mechanism. The combined power generation system using the high-temperature fuel cell according to claim 9, wherein the flow rate is controlled. A fuel cell side power line connected to a power system and transmitting power from the high temperature fuel cell;
A generator-side power line connected to a power system and transmitting power from the generator;
A system operation power line for supplying power into the power generation system;
2. A power switching means capable of arbitrarily switching and connecting at least one connection between the fuel cell side power line and the power system of the generator side power line to the system operation power line. A combined power generation system using the high-temperature fuel cell according to any one of 1 to 10.

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