JP2008066307A - Fuel cell-gas turbine power generating equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fuel cell-gas turbine power generating equipment which can appropriately control the air flow rate supplied to the fuel cell. <P>SOLUTION: The equipment comprises a compressor 3 which compresses the air, a heat exchanging device which heats the air compressed at the compressor 3; a fuel cell which generates electric power with the cell reaction of supplied oxygen in the compressed air and the fuel via an electrolyte, when the compressed air heated by the heat exchanging device is supplied to an air pole and the fuel is supplied to a fuel pole; a combustor 8 to which exhaust air and exhanst fuel gas from the fuel cell is sent; a gas turbine 4 which is equipped coaxially with the compressor 3 and driven, when the combustion gas from the combustor 8 expands; a flow rate adjusting device which adjusts flow rate of the compressed air in the upstream of the heat exchanging device; and a cooling device which cools the exhaust fuel gas from the fuel cell. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell-gas turbine power generation facility in which a fuel cell (solid oxide fuel cell) and a gas turbine are combined.

  A fuel cell is a device that generates electricity by causing an electric cell reaction between air and fuel via an electrolyte, and can generate electric energy with high power generation efficiency. The temperature of the exhaust gas discharged from this fuel cell is high, and the system loss can be reduced by recovering the thermal energy of the exhaust gas by a bottoming cycle such as a gas turbine and a steam turbine and using it for power generation. Power generation efficiency can be obtained.

  In particular, high temperature fuel cells {solid electrolyte fuel cells (SOFC) with an operating temperature of about 1000 ° C and molten carbonate fuel cells (MCFC) with an operating temperature of about 650 ° C} have a high exhaust gas temperature. In the fuel cell-gas turbine power generation facility in which such a high-temperature fuel cell and a gas turbine are combined, power generation can be performed with high efficiency.

  As a fuel cell-gas turbine power generation facility that combines a fuel cell and a gas turbine, for example, it is disclosed in Patent Document 1 and the like.

JP 2001-15134 A

  In a fuel cell-gas turbine power generation facility that combines a fuel cell (for example, SOFC) and a gas turbine, when the facility is stopped, the metal (for example, Ni) that is a cell material is prevented from being oxidized, so that the fuel side is at a high temperature state. It is necessary to supply reducing gas. For this reason, it has been studied to actively cool the fuel cell when the equipment is stopped to save reducing gas.

  Further, various studies have been made to appropriately control the flow rate of air supplied to the fuel cell during operation.

  The present invention has been made in view of the above situation, and in a turbine power generation facility in which a fuel cell and a gas turbine are combined, a fuel cell-gas turbine capable of preventing high-temperature oxidation of the cell material of the fuel cell when the facility is stopped. The purpose is to provide power generation facilities.

  Further, the present invention has been made in view of the above situation, and in a turbine power generation facility that combines a fuel cell and a gas turbine, the fuel cell can be cooled in a short time when the facility is stopped while minimizing the cost. An object of the present invention is to provide a fuel cell-gas turbine power generation facility.

  Another object of the present invention is to provide a fuel cell-gas turbine power generation facility capable of appropriately controlling the flow rate of air supplied to the fuel cell.

  In order to achieve the above object, a fuel cell-gas turbine power generation facility according to the first aspect of the present invention includes a compressor for compressing air, heat exchange means for heating the compressed air compressed by the compressor, Compressed air heated by the heat exchange means is supplied to the air electrode side, and fuel is supplied to the fuel electrode side. The fuel cell generates electric power by causing a cell reaction between oxygen and fuel in the supplied compressed air via the electrolyte. A combustor to which exhaust air and exhaust gas from the fuel cell are sent, a gas turbine that is driven by expansion of combustion gas from the combustor and provided coaxially with the compressor, and upstream of the heat exchange means A flow rate adjusting means for adjusting the flow rate of the compressed air and a cooling means for cooling the exhaust gas from the fuel cell are provided.

  In order to achieve the above object, a fuel cell-gas turbine power generation facility according to a second aspect of the present invention includes a compressor that compresses air, heat exchange means that heats compressed air compressed by the compressor, Compressed air heated by the heat exchange means is supplied to the air electrode side, and fuel is supplied to the fuel electrode side. The fuel cell generates electric power by causing a cell reaction between oxygen and fuel in the supplied compressed air via the electrolyte. A combustor to which exhaust air and exhaust gas from the fuel cell are sent, a gas turbine that is driven by expansion of the combustion gas from the combustor and provided coaxially with the compressor, and a driving force of the gas turbine A generator for converting the gas into the fuel electrode, purge gas supply means for supplying purge gas to the fuel electrode side of the fuel cell when the facility is stopped, and a motor driven by the generator when the facility is stopped so that the compressed air from the compressor is supplied to the air electrode of the fuel cell. On the side Motor driving means to be supplied as reject air, flow rate adjusting means for adjusting the flow rate of compressed air upstream of the heat exchanging means, cooling means for cooling exhaust gas from the fuel cell, and compressed air upstream of the flow rate adjusting means And a circulation path for joining the exhaust gas on the downstream side of the cooling means to the fuel supplied to the fuel electrode side of the fuel cell.

  In the fuel cell-gas turbine power generation facility according to the first invention or the second invention, the fuel cell is a solid oxide fuel cell.

  A fuel cell-gas turbine power generation facility according to a first aspect of the present invention includes a compressor that compresses air, heat exchange means that heats compressed air compressed by the compressor, and heat that is heated by the heat exchange means. Compressed air is supplied to the air electrode side, fuel is supplied to the fuel electrode side, and oxygen and fuel in the supplied compressed air are subjected to a cell reaction via an electrolyte to generate power, and a fuel cell A combustor to which air and exhaust gas are sent, a gas turbine that is driven by expansion of combustion gas from the combustor and provided coaxially with the compressor, and a flow rate of compressed air upstream of the heat exchange means is adjusted. Since the flow rate adjusting means and the cooling means for cooling the exhaust gas from the fuel cell are provided, the flow rate of the compressed air whose temperature is not high can be controlled, and the flow rate of the air supplied to the fuel cell is appropriately controlled. Possible It made.

  A fuel cell-gas turbine power generation facility according to a second aspect of the present invention is a compressor that compresses air, a heat exchange means that heats compressed air compressed by the compressor, and is heated by the heat exchange means. Compressed air is supplied to the air electrode side, fuel is supplied to the fuel electrode side, and oxygen and fuel in the supplied compressed air are subjected to a cell reaction via an electrolyte to generate power, and a fuel cell A combustor to which air and exhaust gas are sent, a gas turbine that is driven by expansion of combustion gas from the combustor and provided coaxially with the compressor, and a generator that converts the driving force of the gas turbine into electric power, A purge gas supply means for supplying purge gas to the fuel electrode side of the fuel cell when the facility is stopped, and a generator is driven by the motor when the facility is stopped to supply compressed air from the compressor as cooling air to the air electrode side of the fuel cell Mo A flow rate adjusting means for adjusting the flow rate of the compressed air upstream of the heat exchanging means, a cooling means for cooling the exhaust gas from the fuel cell, and a refrigerant for cooling the compressed air upstream of the flow rate adjusting means. And a circulation system for merging the exhaust gas on the downstream side of the cooling means with the fuel supplied to the fuel electrode side of the fuel cell, so that the fuel cell side of the fuel cell when the equipment is stopped By supplying purge gas to the battery, it is possible to prevent high-temperature oxidation of the battery material, and when the equipment is stopped, the motor is driven by the motor driving means so that the compressed air from the compressor is supplied to the air electrode side of the fuel cell. By supplying the air as cooling air, it is possible to cool the fuel cell in a short time when the equipment is shut down while minimizing the cost, and to control the flow rate of compressed air at a low temperature By cooling the exhaust gas from the fuel cell together with compressed air as a refrigerant cooling means, it is possible to properly control the flow rate of air supplied to enable the fuel cell by utilizing energy.

  In the fuel cell-gas turbine power generation facility according to the first or second invention, since the fuel cell is a solid oxide fuel cell, an efficient facility combining the solid oxide fuel cell and the gas turbine, It becomes possible to do.

  FIG. 1 shows a schematic system of a fuel cell-gas turbine power generation facility according to an embodiment of the present invention.

  As shown in the figure, the fuel cell-gas turbine power generation facility includes a solid oxide fuel cell (SOFC) 1 as a fuel cell and a turbine facility 2. The turbine equipment 2 includes a compressor 3, a gas turbine 4, and a generator 5 having a motor function for starting. The exhaust gas from the gas turbine 4 is recovered by, for example, an exhaust heat recovery boiler (not shown). The SOFC 1 generates electricity by causing a cell reaction between air (oxygen) and fuel via an electrolyte.

  The air supplied to the SOFC 1 is compressed air compressed by the compressor 3. The compressed air compressed by the compressor 3 is sent to a first air preheater 6 as heat exchange means, and the first air preheater 6 heats the compressed air by exchanging heat with the exhaust gas of the gas turbine 4. The The compressed air heated by the first air preheater 5 is preheated by the internal air preheater 11 and supplied to the air electrode side of the SOFC 1. The fuel is supplied to the fuel electrode side of the SOFC 1 after being subjected to treatment such as desulfurization.

  The fuel-side exhaust gas containing unreacted components of SOFC 1 is sent to a fuel cooler 7 as a cooling means, and the exhaust gas cooled by the fuel cooler 7 is sent to a combustor 8. Further, the exhaust air of the SOFC 1 is recovered by the internal air preheater 11 and sent to the combustor 8. Further, a part of the fuel sent to the SOFC 1 is sent to the combustor 8.

  A part of the exhaust gas on the downstream side of the fuel cooler 7 is joined to the fuel sent from the circulation path 9 as a circulation system to the fuel electrode side of the SOFC 1 via the recirculation blower 10.

  In the combustor 8, the exhaust air recovered by the internal air preheater 11, the exhaust gas cooled by the fuel cooler 6, and a part of the fuel are combusted, and the combustion gas is expanded by the gas turbine 4. Converted to power generation output. The exhaust gas expanded and discharged by the gas turbine 4 is recovered by the first air preheater 6 and sent to the downstream side. A second air preheater 12 is provided in parallel with the first air preheater 6, and a part of the exhaust gas expanded and discharged by the gas turbine 4 is recovered by the second air preheater 12 and sent to the downstream side. It is done.

  On the other hand, a flow rate adjusting valve 13 is provided as a flow rate adjusting means for adjusting the flow rate of the compressed air on the upstream side of the first air preheater 6, and the amount of compressed air sent to the SOFC 1 is controlled by the flow rate adjusting valve 13.

  Since the flow rate adjusting valve 13 is provided on the upstream side of the first air preheater 6, the flow rate of the relatively low temperature (for example, 200 ° C.) compressed air before being heated by the first air preheater 6 is controlled. It will be. For this reason, it is not necessary to use a high-temperature resistant material device, and an expensive device is unnecessary, and an increase in cost can be suppressed. And in order to control comparatively low temperature compressed air, there is little volume change of an apparatus structural member, and it becomes possible to control a flow volume accurately. By the way, when controlling high-temperature compressed air, the volume of the equipment constituent member changes greatly, equipment of precise high temperature resistant material must be used, and it is difficult to control the flow rate with high accuracy. When the flow rate of compressed air of high-temperature compressed air (for example, 400 ° C. or higher) is controlled by the flow rate adjustment valve, the volume change accompanying the temperature change of the flow rate adjustment valve component increases, and the shutoff property of the flow rate adjustment valve decreases. End up.

  A bypass passage 14 that branches a part of the compressed air on the upstream side of the flow regulating valve 13 is provided, and the bypass passage 14 is connected to the fuel cooler 7. The fuel is cooled in the fuel cooler 7 by the compressed air sent from the bypass passage 14, and the compressed air subjected to heat exchange is preheated by the second air preheater 12 and sent to the combustor 8. For this reason, it is not necessary to supply an external refrigerant as a cooling medium of the fuel cooler 7, and the system efficiency can be improved by effectively using energy.

  It is also possible to directly supply the combustor 8 with the compressed air heat-exchanged by the fuel cooler 7 without providing the second air preheater 12. It is also possible to apply an external refrigerant (exclusive cooling water or the like) as a cooling medium for the fuel cooler 7.

  In the fuel cell-gas turbine power generation facility having the above-described configuration, the fuel is supplied to the fuel electrode of the SOFC 1, and the compressed air that is compressed by the compressor 3 and the flow rate is adjusted to a predetermined state by the flow rate adjusting valve 13 is the first air. The preheater 6 and the internal air preheater 11 are heated to a predetermined temperature and supplied to the SOFC 1. In SOFC1, power generation is performed by a cell reaction of oxygen and fuel in compressed air.

  The exhaust gas containing unreacted components is cooled by the fuel cooler 7 and sent to the combustor 8, and a part of the exhaust gas cooled by the fuel cooler 7 passes through the recirculation blower 10 through the recirculation blower 10. Combined with the fuel sent to the fuel electrode side. Exhaust air containing unreacted oxygen is recovered by the internal air preheater 11 and sent to the combustor 8. A part of the fuel is sent to the combustor 8.

  The combustion gas generated by the combustor 8 is expanded by the gas turbine 4 to operate the gas turbine 4, and the exhaust gas from the gas turbine 4 is recovered by heat with an exhaust heat recovery boiler (not shown) and released.

  In the fuel cell-gas turbine power generation facility described above, the flow rate of the compressed air on the upstream side of the first air preheater 6 is controlled by the flow rate adjusting valve 13 and sent to the SOFC 1, so that it is heated by the first air preheater 6. The flow rate of the previous relatively low temperature (for example, 200 ° C.) compressed air is controlled, so that the volume change of the constituent members of the flow rate adjusting valve 13 is small, and the flow rate can be controlled with high accuracy. In addition, since it is not necessary to control the flow rate of the high-temperature compressed air, an inexpensive flow rate adjustment valve 13 can be applied.

  By the way, the SOFC1, which is a high-temperature fuel cell, is a solid electrolyte fuel cell having an operating temperature of about 1000 ° C., and therefore is at a high temperature of about 1000 ° C. when the facility is stopped. SOFC1 has good heat retention and is not easily cooled, and in a high temperature state, SOFC1 battery material (for example, Ni) may be exposed to high temperature to cause oxidation. Therefore, it is necessary to prevent oxidation and cool the SOFC 1 in a short time when the equipment is stopped.

  For this reason, the fuel cell-gas turbine power generation facility of this embodiment is provided with a reducing gas supply means for supplying a reducing gas (for example, H, N) to the fuel electrode side of the SOFC 1 when the facility is stopped. Further, in order to perform cooling in a short time, motor driving means is provided for supplying compressed air from the compressor 3 to the air electrode side of the SOFC 1 as cooling air.

  The reducing gas supply means will be described.

  As shown in the figure, a reducing gas passage 21 is connected to the fuel electrode side of the SOFC 1, and reducing gas (for example, H, N) is supplied from the reducing gas passage 21 to the fuel electrode of the SOFC 1 when the facility is stopped. .

  For this reason, even if the battery material (for example, Ni) of SOFC1 is exposed to a high temperature when the facility is stopped, the high temperature oxidation can be prevented by the reducing gas. Further, the SOFC 1 can be cooled by the reducing gas itself.

  The motor driving means will be described.

  As shown in the figure, the generator 5 having the motor function for starting is a motor that drives the generator 5 in a state different from the time of starting (motor driving for a long time) separately from the normal control function. Control means 23 is provided. When the facility is stopped, the generator 5 is motor-driven by the motor control means 23, and the compressed air from the compressor 3 is supplied to the air electrode side of the SOFC 1 as cooling air.

  For this reason, the cooling air is sent to the SOFC 1 when the facility is stopped, and the SOFC 1 can be cooled in a short time. And since the generator 5 is driven by the motor in a state different from the start-up state without providing a dedicated cooling air supply means, a minimum amount of cooling equipment (cylinder and blower) is installed without any additional installation. Cooling air can be supplied to the SOFC 1 simply by adding equipment (control system for the generator 5). For this reason, it is not necessary to continue supplying the reducing gas in a high temperature state, and the amount of reducing gas can be reduced.

  Since the fuel cell-gas turbine power generation facility described above includes the reducing gas supply means and the motor drive means, it is possible to prevent high-temperature oxidation of the SOFC1 battery material (for example, Ni) when the facility is stopped, The SOFC 1 can be cooled in a short time without increasing the device configuration.

  In addition, when the generator 5 is driven by the motor by the motor control means 23 and the compressed air from the compressor 3 is supplied to the air electrode side of the SOFC 1 as cooling air, the cooling air is SOFC 1 due to the pressure loss relationship of the piping. Sent to the air electrode side. As shown in the figure, for example, a shutoff valve 25 is provided in the bypass passage 14, and the bypass passage 14 is shut off when the motor 5 is driven by the motor control means 23, so that the cooling air supplies the SOFC 1. It is also possible to positively prevent sending to the combustor 8 side without going through.

  Further, as shown in FIG. 2, the first air preheater 6 and the second air preheater 12 can be arranged in series. Moreover, it is also possible to set it as the installation which provided either the reducing gas supply means and the motor drive means. Further, without providing the reducing gas supply means and the motor driving means, the flow rate adjusting valve 13 is provided upstream of the first air preheater 6, and the compressed air from the compressor 3 is supplied to the fuel cooler 7 through the bypass passage 14. It is also possible to set it as the installation of the structure applied as a refrigerant | coolant.

1 is a schematic system diagram of a fuel cell-gas turbine power generation facility according to an embodiment of the present invention. FIG. 3 is a schematic system diagram of a fuel cell-gas turbine power generation facility according to another embodiment of the present invention.

Explanation of symbols

1 Solid electrolyte fuel cell (SOFC)
DESCRIPTION OF SYMBOLS 2 Turbine equipment 3 Compressor 4 Gas turbine 5 Generator 6 1st air preheater 7 Fuel cooler 8 Combustor 9 Circulation path 10 Recirculation blower 11 Internal air preheater 12 2nd air preheater 13 Flow control valve 14 Bypass flow Path 21 reducing gas path 23 motor control means 25 shut-off valve

Claims (3)

A compressor for compressing air;
Heat exchange means for heating the compressed air compressed by the compressor;
Compressed air heated by the heat exchange means is supplied to the air electrode side, and fuel is supplied to the fuel electrode side. The fuel cell generates electric power by causing a cell reaction between oxygen and fuel in the supplied compressed air via the electrolyte. When,
A combustor to which exhaust air and exhaust gas from the fuel cell are sent;
A gas turbine driven by expansion of combustion gas from the combustor and provided coaxially with the compressor;
A flow rate adjusting means for adjusting the flow rate of the compressed air on the upstream side of the heat exchange means;
A fuel cell-gas turbine power generation facility comprising cooling means for cooling exhaust fuel gas from the fuel cell. A compressor for compressing air;
Heat exchange means for heating the compressed air compressed by the compressor;
Compressed air heated by the heat exchange means is supplied to the air electrode side, and fuel is supplied to the fuel electrode side. The fuel cell generates electric power by causing a cell reaction between oxygen and fuel in the supplied compressed air via the electrolyte. When,
A combustor to which exhaust air and exhaust gas from the fuel cell are sent;
A gas turbine driven by expansion of combustion gas from the combustor and provided coaxially with the compressor;
A generator that converts the driving force of the gas turbine into electric power;
Purge gas supply means for supplying purge gas to the fuel electrode side of the fuel cell when the facility is stopped;
Motor driving means for driving the generator when the equipment is stopped and supplying compressed air from the compressor as cooling air to the air electrode side of the fuel cell;
A flow rate adjusting means for adjusting the flow rate of the compressed air on the upstream side of the heat exchange means;
A cooling means for cooling the exhaust fuel gas from the fuel cell;
A bypass flow path for the compressed air on the upstream side of the flow rate adjusting means as a refrigerant of the cooling means;
A fuel cell-gas turbine power generation facility comprising: a circulation system for joining exhaust fuel gas on the downstream side of the cooling means to fuel supplied to the fuel electrode side of the fuel cell. The fuel cell-gas turbine power generation facility according to claim 1 or 2,
A fuel cell-gas turbine power generation facility, wherein the fuel cell is a solid oxide fuel cell.

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