JP4218055B2 - Fuel cell power generator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molten carbonate fuel cell power generator.
[0002]
[Prior art]
Molten carbonate fuel cells have features that are not found in conventional power generators, such as high efficiency and little impact on the environment. They attract attention as a power generation system that follows hydropower, thermal power, and nuclear power, and are currently under intense research. It is being advanced.
[0003]
FIG. 3 is a diagram showing an example of power generation equipment using a molten carbonate fuel cell using city gas as fuel. In FIG. 3, the power generation facility is a fuel that generates power from a reformer 22 that reforms a fuel gas (city gas) mixed with steam into an anode gas containing hydrogen, a cathode gas containing oxygen, and an anode gas containing hydrogen. The anode gas generated by the reformer 22 is supplied to the fuel cell 20 through the anode gas line 2 and consumes most of the fuel cell 20 to become anode exhaust gas. A combustion gas is supplied to the catalytic combustor 23 through the line 4.
[0004]
In the catalytic combustor 23, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas are combusted to generate high-temperature combustion exhaust gas, which is supplied to the heating chamber of the reformer 22, and this combustion exhaust gas is used to reform the chamber. Then, the fuel gas is reformed by the reforming catalyst in the reforming chamber to obtain anode gas. The anode gas exchanges heat with the fuel gas mixed with the vapor flowing through the fuel gas line 1 by the fuel preheater 24 and is supplied to the anode of the fuel cell 20. The combustion exhaust gas that has left the heating chamber is supplied to the cathode by the carbon dioxide recycling blower 32 in the carbon dioxide recycling line 7. The combustion exhaust gas contains a large amount of carbon dioxide, and becomes a supply source of carbon dioxide necessary for the battery reaction. Air from the air line 8 is supplied to the outlet side of the carbon dioxide recycle blower 32 to supply oxygen necessary for the cell reaction of the cathode. A part of the cathode exhaust gas discharged from the cathode is supplied to the cathode through the circulation line 3. The cathode exhaust gas, combustion exhaust gas, and air are mixed to form cathode gas and supplied to the cathode. An anode exhaust gas reforming line 6 is provided on the anode exit side, and anode exhaust gas containing unburned fuel is reformed by an adiabatic reformer 36 and supplied to the anode. The adiabatic reformer 36 fills the container with a reforming catalyst and insulates it to keep the anode exhaust gas in a high temperature state and convert it into a reformed gas by catalytic action.
[0005]
The cathode gas reacts in the fuel cell 20 to become high-temperature cathode exhaust gas, part of which circulates through the cathode through the circulation line 3, the other part is supplied to the catalytic combustor 23 through the cathode exhaust gas line 5, and the rest After being combusted by the combustor 38 together with the anode exhaust gas and recovering power by the turbine compressor 28 that drives a compressor that compresses air, the exhaust heat recovery steam generator 30 further recovers thermal energy and exhausts it outside the system. The The steam generated by the exhaust heat recovery steam generator 30 enters the fuel gas line 1 through the steam line 9, mixes with the fuel gas, and is sent to the reformer 22.
[0006]
The carbon dioxide gas recycling line 7 is provided with a carbon dioxide gas recycling blower 32. Since the temperature of the gas to be handled is about 650 ° C., compressed air is used for the shaft seal of the blower 32, and compressed air is supplied from the in-house air compressor 40. An anode recycle blower 34 is also provided in the anode exhaust gas reforming line 6, and the temperature of the gas to be handled is about 650 ° C. Therefore, nitrogen gas is used for the shaft seal of the blower 34 and nitrogen is supplied from the nitrogen gas supply device 42. Is done.
[0007]
[Problems to be solved by the invention]
The amount of compressed air used for the carbon dioxide gas recycle blower 32 is a considerable amount, for example, 60 Nm ³ / h, which occupies a large proportion of the power for in-house air and is a factor in reducing plant efficiency. The anode recycle blower 34 also uses a large amount of nitrogen gas, for example, 30 Nm ³ / h, which increases the operating cost.
[0008]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel cell power generator that greatly reduces in-house power and operation costs.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel cell for generating electricity with an anode gas containing hydrogen supplied to the anode and a cathode gas containing oxygen supplied to the cathode, and a reformer for the fuel gas and steam. An anode gas line that is supplied to the anode as anode gas, an anode exhaust gas reforming line that reforms the anode exhaust gas with an adiabatic reformer and supplies it to the anode, and the anode exhaust gas and the cathode exhaust gas are burned by a catalytic combustor. A carbon dioxide gas recycling line that generates exhaust gas and heats the reformer and then supplies it to the cathode. The combustion gas that burns the anode exhaust gas and cathode exhaust gas rotates the turbine to drive the compressor to generate compressed air and supply it to the cathode. Turbine compressor, and exhaust heat recovery steam generator that generates steam from the turbine exhaust of the turbine compressor and supplies it to the reformer A recycle blower for injecting gas into the anode exhaust gas reforming line and the carbon dioxide gas recycling line to perform shaft sealing, and the shaft sealing gas. The steam generated by the exhaust heat recovery steam generator is used.
[0010]
Steam generated by the exhaust heat recovery steam generator is sent to the fuel gas line, mixed with the fuel gas, sent to the reformer, and used to generate anode gas. However, there is considerable capacity in terms of capacity. Since both the recycle blowers are used for transferring a gas at 600 ° C. or higher, steam can be used as the shaft seal gas. As a result, a reduction in power for in-house compressed air and a reduction in operating cost due to the need for expensive nitrogen gas are realized.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the fuel cell power generator of the present invention. The same reference numerals as those in FIG. 3 represent the same lines and devices. Since the apparatus of FIG. 3 has been described in detail, differences from FIG. 3 will be described. In FIG. 1, the air compressor 40 that supplies compressed air to the carbon dioxide gas recycle blower 32 and the nitrogen gas supply device 42 that supplies nitrogen gas to the anode recycle blower 34 in FIG. Are connected to the respective blowers 32 and 34 to supply steam as shaft seal gas. As a result, the same sealing effect can be obtained as when compressed air is supplied to the carbon dioxide recycle blower 32 and nitrogen gas is supplied to the anode recycle blower 34.
[0012]
FIG. 2 is a view showing the structure of the shaft seal used in the carbon dioxide gas recycle blower 32 and the anode recycle blower 34. A heat resistant material sleeve 51 made of graphite is fixed to the blower shaft 50, and a mating ring 52 made of SiC is fixed to the sleeve 51 and rotates together with the blower shaft 50. A sealing ring 53 made of carbon that contacts the mating ring 52 at a sliding surface 55 is provided, and is supported by the casing 54 so as to be slidable in the direction of the blower shaft 50. The seal ring 53 is pressed against the mating ring 52 by a spring through a segment seal 56 so as to keep the seal. The casing 54 is provided with a seal gas injection port 57, and steam is injected as a seal gas. The steam passes through a path indicated by an arrow, passes through a labyrinth seal portion 58 fixed to the casing 54, and enters the blower. By injecting steam having a pressure higher than the blower internal pressure into the blower in this way, leakage of hot gas from the blowers 32 and 34 is prevented.
[0013]
【The invention's effect】
As is clear from the above description, the present invention can reduce the power of the air compressor by performing the blower that has been conventionally sealed with compressed air or nitrogen gas with the steam from the steam generator in the system. In addition, the operation cost can be reduced by eliminating the need for nitrogen supply.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a fuel cell power generator according to the present invention.
FIG. 2 is a diagram showing a configuration of a shaft seal of a high-temperature blower.
FIG. 3 is a diagram showing a configuration of a conventional fuel cell power generator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel gas line 2 Anode gas line 3 Circulation line 4 Anode exhaust gas line 5 Cathode exhaust gas line 6 Anode exhaust gas reforming line 7 Carbon dioxide recycling line 8 Air line 9 Steam line 20 Fuel cell 22 Reformer 23 Catalytic combustor 24 Fuel preheating 26 Desulfurizer 28 Turbine compressor 30 Waste heat recovery steam generator 32 Carbon dioxide gas recycle blower 34 Anode recycle blower 36 Adiabatic reformer 38 Combustor 40 Air compressor 42 Nitrogen gas supply device 50 Blower shaft 51 Sleeve 52 Mating ring 53 Seal ring 54 Casing 55 Sliding surface 56 Segment seal 57 Seal gas inlet 58 Labyrinth seal part

Claims (1)

A fuel cell that generates electricity with an anode gas containing hydrogen supplied to the anode and a cathode gas containing oxygen supplied to the cathode, an anode gas line that supplies fuel gas and steam to the anode as an anode gas in a reformer, and an anode An anode exhaust gas reforming line that reforms exhaust gas with an adiabatic reformer and supplies it to the anode, and burns anode exhaust gas and cathode exhaust gas with a catalytic combustor to generate combustion exhaust gas, heats the reformer, and then supplies it to the cathode A carbon dioxide gas recycling line, a turbine compressor that rotates the turbine by combustion gas combusting anode exhaust gas and cathode exhaust gas, generates a compressed air by driving a compressor, and supplies the compressed air to the cathode, and a turbine exhaust of the turbine compressor An exhaust heat recovery steam generator for generating steam and supplying it to the reformer, and a fuel cell power generator comprising: The anode exhaust gas reforming line and the carbon dioxide gas recycling line are provided with a recycle blower for injecting gas to seal the shaft, and the steam generated by the exhaust heat recovery steam generator is used as the shaft sealing gas. A fuel cell power generator characterized by that.

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