JP3508228B2 - Method of increasing temperature at startup of molten carbonate fuel cell power generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for increasing the temperature of a molten carbonate fuel cell power generator at startup. 2. Description of the Related Art Molten carbonate fuel cells have features that are not present in conventional power generation devices, such as high efficiency and little impact on the environment. Attention has been paid to the system, and intensive research is currently being conducted in various countries around the world. FIG. 2 shows an example of a molten carbonate fuel cell power generator using natural gas as fuel. As shown in the drawing, a power generator includes a reformer 3 for reforming a fuel gas 1 in which natural gas and water vapor are mixed into an anode gas 2 containing hydrogen, a cathode gas 4 containing oxygen, and the anode gas 2.
And a fuel cell 5 for generating electricity from the fuel cell 5. The anode gas 2 produced by the reformer 3 is supplied to the anode An of the fuel cell 5, and a large part of the fuel gas is consumed in the fuel cell 5 and the anode exhaust gas is discharged. 6 and supplied to the combustion chamber Co of the reformer 3 as combustion gas by the anode exhaust gas line 7. The fuel cell 5 is housed in the storage container 8 to prevent flammable gas and the like from leaking to the outside to enhance safety. The reformer 3 burns combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 6 leaving the fuel cell 5 and a part of the cathode exhaust gas 9 to produce a high-temperature combustion exhaust gas 10. It is composed of a combustion chamber Co to be generated and a reforming chamber Re which is filled with a reforming catalyst and reforms the fuel gas 1 by heat transfer from the combustion chamber Co. The high-temperature anode gas 2 containing hydrogen is cooled through the fuel heater 11 and supplied to the anode An of the fuel cell 5. On the other hand, the combustion exhaust gas 10 whose temperature has been lowered by heat radiation is cooled by an air preheater 13 through an exhaust gas supply line 12, water is removed by a condenser 14 and a water / water separation drum 15, and pressurized by a low temperature blower 16, 17 and heated by the air preheater 13 to enter the cathode circulation line 18. The cathode gas 4 partially reacts with the cathode Ca of the fuel cell 5 to become a high-temperature cathode exhaust gas 9,
After the power is recovered by being guided to the turbine compressor 21 that compresses the air 17 through the cathode exhaust gas line 34, the steam 23 is further generated by the steam generator 22 for exhaust heat recovery so as to be discharged out of the system. Has become. The steam 23 is sent to a fuel gas supply line 25 by a steam line 24 and mixed with a source gas 26 such as a natural gas sent from a source blower 27 to become a fuel gas 1 and a reforming chamber Re of the reformer 3.
It is supplied to. A part of the cathode exhaust gas 9 of the fuel cell 5 is supplied to the air preheater 13 by a cathode circulation line 18.
And is circulated and supplied to the cathode Ca of the fuel cell 5 as the cathode gas 4 by the high-temperature blower 28. The air 17 compressed by the air compressor C of the turbine compressor 21 joins with the flue gas 10 from which moisture has been removed at the outlet of the low-temperature blower 16. The air line 51 of the turbine compressor 21 is provided with a bypass line 30 having the air blower 29,
Air 1 compressed by air compressor C of turbine compressor 21
The air blower 29 is used as a backup when the capacity of the air blower 7 is insufficient. That is, the air blower 29 is connected to the fuel cell 5
Even when the flow rate of the cathode exhaust gas 9 sent to the turbine compressor 21 is small, such as during a low load operation including the start-up of the air, the air 1
In order to satisfy the requirement of 7, the air compressor C is operated so as to compensate for the shortage. In FIG. 2, a fuel supply valve 31 is provided at an outlet of a raw material blower 27, and a fuel gas supply line 25 on the outlet side of the fuel supply valve 31 has an N ₂ gas purge having an N ₂ supply valve 32. Line 33 is connected. On the other hand, the molten carbonate fuel cell power generator is provided with a hot air generator 50 for startup used at the time of startup, and the hot air generator 50 for startup is provided with an air compressor of the turbine compressor 21. C or a hot air generating furnace air line 52 branched from an air line 51 through which the air 17 is pumped by the air blower 29 is connected, and a hot air generating furnace air valve 53 is provided in the middle of the hot air generating furnace air line 52. A fuel line 54 for a hot air generator, which is branched from the fuel gas supply line 25 between the raw material blower 27 and the fuel supply valve 31, is connected to the fuel line 5 for the hot air generator.
A fuel supply valve 55 for a hot air generator is provided in the middle of the furnace 4, and a starting heater 57 for heating the cathode gas 4 by the exhaust gas 56 discharged from the hot air generator 50 for starting is provided in the cathode circulation line 18, An exhaust gas line 58 for a hot air generating furnace through which the exhaust gas 56 after heating the cathode gas 4 by the heating heater 57 flows is branched from the cathode exhaust gas line 34 to a cathode branch line 59 which leads to the combustion chamber Co of the reformer 3. They are joined on the way. The reforming furnace fuel line 6 branches from the middle of the hot air generating furnace fuel line 54 upstream of the hot air generating furnace fuel supply valve 55 and communicates with the anode exhaust gas line 7.
0, a fuel supply valve 61 for the reformer is provided in the middle of the fuel line 60 for the reforming furnace, and a main air valve 62 is provided in the middle of the air line 51 downstream from the branch point of the air line 52 for the hot blast generating furnace. Is provided. When the molten carbonate fuel cell power generator as described above is started, the fuel supply valve 31 and the reformer fuel supply valve 6
1 and closes the main air valve 62, is supplied from the N ₂ gas purge line 33 to open the N ₂ supply valve 32 slightly small portions N ₂ gas, circulating the gas in the cathode circulation line 18 by the driving of the high-temperature blower 28 In this state, the air valve 53 for the hot air generating furnace is opened to drive the air blower 29 to supply the air 17 to the hot air generating furnace 50 for starting, and the fuel supply valve 55 for the hot air generating furnace is opened to remove the raw material blower 27. The raw material gas 26 such as natural gas is supplied to the hot air generator 50 for driving and starting,
The high temperature exhaust gas 56 generated by combustion in the hot air generating furnace 50 for starting is led to the starting heater 57, and the gas circulated in the cathode circulation line 18 is heated to heat the fuel cell 5. The exhaust gas 56 discharged from the hot air generator 50 for starting and radiated heat by the heater 57 for starting is supplied to the combustion chamber Co of the reformer 3 via the cathode branch line 59, By opening the dexterous fuel supply valve 61 and supplying a part of the raw material gas 26 such as natural gas to the combustion chamber Co of the reformer 3 via the anode exhaust gas line 7, the raw material gas 26 is contained in the exhaust gas 56 in the combustion chamber Co. The raw material gas 26 is burned using the remaining O _2, and the temperature of the reformer 3 is raised.
When the temperature reaches 70 ° C.), the supply of the raw material gas 26 to the hot air generating furnace 50 for starting is stopped by closing the fuel supply valve 55 for hot air generating furnace, and the air valve 53 for hot air generating furnace is closed to generate hot air for starting. The supply of the air 17 to the furnace 50 is stopped, and the fuel supply valve 61 for the reformer is closed to supply the raw material gas 2 to the combustion chamber Co.
6, the supply of N ₂ gas is stopped by closing the N ₂ supply valve 32, and the main air valve 62 is opened, and the air 17 from the air blower 29 is preheated by the low temperature blower 16. The fuel is supplied to the combustion chamber Co of the reformer 3 through the heater 13, the cathode circulation line 18, the high-temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34, and the cathode branch line 59, and the fuel supply valve 31 , The supply of the fuel gas 1 obtained by adding the steam 23 to the raw material gas 26 to the reforming chamber Re of the reformer 3 is started, and the operation is shifted to a steady operation. After the transition from the startup of the molten carbonate fuel cell power generator to the steady operation, the flow rate of the cathode exhaust gas 9 sent to the turbine compressor 21 is secured, and the required amount of air 17 by the air compressor C is reduced. When it becomes full, the air blower 29 is stopped. [0015] However, in the molten carbonate fuel cell power generator as described above, the hot air generating furnace 50 for start-up is used while the fuel cell 5 and the reformer 3 are being heated at the time of start-up. Unburned components and castable splatters in the furnace may accumulate on the combustion-side catalyst layer of the reformer 3, blocking the flow passage, making the operation impossible. In view of such circumstances, the present invention makes it possible to raise the temperature of the reformer 3 without using the exhaust gas 56 discharged from the hot air generating furnace 50 for starting up as the temperature of the reformer 3. In addition, it is possible to avoid accumulation of unburned components and castable splatters in the furnace on the combustion side catalyst layer of the reformer 3, thereby avoiding blockage of the flow path and making operation impossible. It is an object of the present invention to provide a method for raising the temperature of a molten carbonate fuel cell power generator at startup which can be prevented. According to the present invention, the fuel gas 1 obtained by adding steam 23 to the raw material gas 26 from the raw material blower 27 during the steady operation is led to the reforming chamber Re of the reformer 3. The anode gas 2 containing the reformed hydrogen containing the reformed hydrogen is supplied to the fuel cell 5
And the cathode gas 4 is supplied to the cathode Ca of the fuel cell 5 to generate electricity. The cathode exhaust gas 9 from the cathode Ca is supplied to the turbine T of the turbine compressor 21 through the cathode exhaust gas line 34. And a part of the cathode exhaust gas 9 is led to the combustion chamber Co of the reformer 3 through the cathode branch line 59, and the anode exhaust gas 6 from the anode An is passed through the anode exhaust line 7 to the reformer. The combustion exhaust gas 10 from the reformer 3 is guided to the steam / water separation drum 15 via the air preheater 13 and the condenser 14 by being guided to the combustion chamber Co of the combustion chamber 3 for combustion. 21 and the air compressor of the turbine compressor 21.
The air 17 from the air blower 29 in the bypass line 30 provided in the exhaust gas 51 and the combustion exhaust gas 10 pressurized by the low-temperature blower 16 through the steam separator 15 and a part of the cathode exhaust gas 9 together with the cathode circulation line The cathode gas 4 is supplied by the high-temperature blower 28 through the cathode gas 4.
This is a method for raising the temperature at the time of startup of the molten carbonate fuel cell power generator in which the gas is supplied to the cathode Ca of the fuel cell 5, and at the time of startup, the gas in the cathode circulation line 18 is circulated by driving the high-temperature blower 28. In this state, the air 17 from the air blower 29 is supplied to the hot air generating furnace 50 for starting, and the raw material gas 26 from the raw material blower 27 is supplied to the hot air generating furnace 50 for starting. The high temperature exhaust gas 56 due to the combustion generated in the above is led to the turbine T of the turbine compressor 21 via a starting heater 57 provided in the middle of the cathode circulation line 18, and the gas circulated in the cathode circulation line 18 is discharged. By heating, the temperature of the fuel cell 5 is raised, and when the inlet and outlet temperatures of the fuel cell 5 become equal to or higher than the temperature at which the electrolyte is melted and a wet seal can be performed. Air 1 from the air blower 29
A part of 7 is passed through the air preheater 13, the cathode circulation line 18, the high temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34, and the cathode branch line 59 by the low temperature blower 16, and is supplied to the reformer 3. A part of the raw material gas 26 from the raw material blower 27 is introduced into the combustion chamber Co of the reformer 3 through the fuel supply valve 61 for the reformer.
o, the raw material gas 26 is burned in the combustion chamber Co, and the temperature of the reformer 3 is raised. When the temperature of the reformer 3 reaches a required temperature at which reforming is possible, the starting The supply of the raw material gas 26 to the hot air generator 50 is stopped, the supply of the air 17 to the hot air generator 50 for startup is stopped, and the supply of the raw gas 26 to the combustion chamber Co of the reformer 3 is stopped. On the other hand, the air 17 from the air compressor C and the air blower 29 in the turbine compressor 21 is
Supply to the combustion chamber Co of the reformer 3 through the air preheater 13, the cathode circulation line 18, the high-temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34, and the cathode branch line 59. The supply of the fuel gas 1 obtained by adding the steam 23 to the gas 26 to the reforming chamber Re of the reformer 3 is started, and the operation shifts to a steady operation. Therefore, when the molten carbonate fuel cell power generator is started up, the turbine compressor 21 is driven while the gas in the cathode circulation line 18 is circulated by driving the high-temperature blower 28.
To the bypass line 30 provided in the air line 51
It takes supplies to start hot air generating furnace 50 air 17 from the air blower 29, the raw material gas 26 from the raw material blower 27 supplies to the starting hot air generator furnace 50, occurs at the starting hot air generator furnace 50 combustion The high temperature exhaust gas 56 is supplied to the starting heater 5 provided in the middle of the cathode circulation line 18.
7 to the turbine T of the turbine compressor 21,
By heating the gas circulated in the cathode circulation line 18, the temperature of the fuel cell 5 is raised, and the fuel cell 5
When the temperature of the inlet and outlet of the air becomes equal to or higher than the temperature at which the electrolyte is melted and a wet seal is formed, a part of the air 17 from the air blower 29 is removed by the low-temperature blower 16 to the air preheater 13, the cathode circulation line 18, the high-temperature Blower 28, starting heater 57, fuel cell 5, cathode exhaust gas line 3
4. Combustion chamber C of reformer 3 via cathode branch line 59
o and the raw material gas 2 from the raw material blower 27
6 is supplied to the combustion chamber Co of the reformer 3, and the combustion chamber C
In step o, the raw material gas 26 is burned, the temperature of the reformer 3 is raised, and when the temperature of the reformer 3 reaches a required temperature at which reforming is possible, the raw material gas 26
And the supply of air 17 to the hot air generator 50 for startup is stopped, and the combustion chamber Co of the reformer 3 is stopped.
While the supply of the raw material gas 26 to the turbine compressor 21 is stopped, the air 17 from the air compressor C and the air blower 29 in the turbine compressor 21 is separated by the low-temperature blower 16 into the air preheater 13,
The steam is supplied to the combustion chamber Co of the reformer 3 via the cathode circulation line 18, the high-temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34, and the cathode branch line 59, and the steam 23 is supplied to the raw material gas 26. If the supply of the added fuel gas 1 to the reforming chamber Re of the reformer 3 is started and the operation is shifted to the steady operation, the exhaust gas 56 discharged from the starting hot-air generating furnace 50 is discharged to the reformer 3. Since it is possible to raise the temperature of the reformer 3 even if it is not used for raising the temperature, it is generated in the hot air generator 50 for startup during the heating of the fuel cell 5 and the reformer 3 at startup. Unburned components, castable scattered materials in the furnace, and the like do not accumulate on the combustion-side catalyst layer of the reformer 3, and there is no concern that the flow path will be blocked, and long-time operation can be performed. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a molten carbonate for practicing the method of the present invention.
An example of a type fuel cell power plant, in the figure, portions denoted by the same reference numerals as in FIG. 2 represents the same parts, but the basic configuration is the same as the conventional one shown in FIG. 2, As shown in FIG. 1, the present embodiment is characterized in that an exhaust gas line 58 for a hot air generating furnace through which an exhaust gas 56 after heating a cathode gas 4 by a starting heater 57 is connected to a branch point of a cathode branch line 59. It is merged with the cathode exhaust gas line 34 on the further downstream side, and the following operation is performed when the molten carbonate fuel cell power generator is started. [0021] That is, at the time of start-up of the molten carbonate fuel cell power plant, closes the main air valve 62 and the fuel supply valve 31 and the reforming dexterity fuel supply valve 61, slightly open N ₂ supply valve 32 N ₂
While the N ₂ gas is supplied little by little from the gas purge line 33 and the gas in the cathode circulation line 18 is circulated by driving the high-temperature blower 28, the air valve 53 for the hot-air generating furnace is opened to drive the air blower 29. The air 17 is supplied to the hot air generating furnace 50 for starting, and the fuel supply valve 55 for hot air generating furnace is opened to drive the raw material blower 27 to supply the raw gas 26 such as natural gas to the hot air generating furnace 50 for starting. -Temperature exhaust gas 5 due to combustion generated in the hot-air generator 50
6 to the turbine T of the turbine compressor 21 via a starting heater 57 provided in the middle of the cathode circulation line 18.
The fuel cell 5 is heated by heating the gas circulated through the cathode circulation line 18. The inlet and outlet temperatures of the fuel cell 5 are adjusted to a temperature (about 580) at which the electrolyte melts and a wet seal is formed.
℃) or more, the main air valve 62 is opened and the low-temperature blower 16 is driven, and a part of the air 17 from the air blower 29 is removed by the low-temperature blower 16 to the air preheater 1.
3, the cathode circulation line 18, the high-temperature blower 28, the starting heater 57, the fuel cell 5, the cathode exhaust gas line 34,
The fuel gas is introduced into the combustion chamber Co of the reformer 3 through the cathode branch line 59, and a part of the raw material gas 26 from the raw material blower 27 is released by opening the fuel supply valve 61 for the reformer. The raw material gas 26 is burned in the combustion chamber Co, and the temperature of the reformer 3 is raised. When the temperature of the reformer 3 reaches a required temperature (approximately 770 ° C.) at which reforming is possible, the fuel supply valve 55 for the hot blast generating furnace is closed to feed the raw material gas to the hot blast generating furnace 50 for starting. 26, the supply of air 17 to the hot air generator 50 for startup is stopped by closing the air valve 53 for the hot air generator, and the fuel supply valve 61 for the reformer is closed to close the reformer 3. The supply of the raw material gas 26 to the combustion chamber Co is stopped, and the main air valve 62 is opened to open the turbine compressor 2.
1 from the air compressor C and the air blower 29
7, a low-temperature blower 16, an air preheater 13, a cathode circulation line 18, a high-temperature blower 28, a starting heater 57,
The fuel gas is supplied to the combustion chamber Co of the reformer 3 via the fuel cell 5, the cathode exhaust gas line 34 and the cathode branch line 59, and the reforming chamber Re of the fuel gas 1 in which the steam 23 is added to the raw material gas 26 is provided. Supply to the furnace and shift to steady operation. As a result, it is possible to raise the temperature of the reformer 3 without using the exhaust gas 56 discharged from the hot air generator 50 for starting up the temperature of the reformer 3. During the heating of the fuel cell 5 and the reformer 3 at the time, the unburned components generated in the hot air generator 50 for start-up and castable scattered materials in the furnace do not accumulate on the combustion side catalyst layer of the reformer 3. In addition, the operation can be performed for a long time without fear of blockage of the flow path. In this way, the temperature of the reformer 3 can be raised without using the exhaust gas 56 discharged from the hot air generator 50 for starting up the temperature of the reformer 3. It is possible to eliminate the accumulation of unburned components and castable splatters in the furnace on the combustion-side catalyst layer of the reformer 3, thereby avoiding blockage of the flow path and preventing operation failure. It should be noted that the method of raising the temperature of the molten carbonate fuel cell power generator at the time of startup according to the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention. Of course, it can be added. As described above, as described above, the molten carbonic acid of the present invention
According to the method for raising the temperature of the salt fuel cell power generator at the time of startup, the exhaust gas 56 discharged from the hot air generator 50 for startup is supplied to the reformer 3.
The temperature of the reformer 3 can be increased without being used to raise the temperature of the reformer 3, and the combustion side catalyst layer of the reformer 3 such as unburned components generated in the hot air generator 50 for start-up and castable scattered materials in the furnace. There is an excellent effect that it is possible to prevent the passage from being blocked by eliminating the accumulation on the fuel cell and to prevent the operation from being disabled.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram of a molten carbonate fuel cell power generation device for implementing a method of the present invention. FIG. 2 is an overall configuration diagram of a conventional molten carbonate fuel cell power generator. [Description of Signs] 1 Fuel gas 2 Anode gas 3 Reformer 4 Cathode gas 5 Fuel cell 6 Anode exhaust gas 7 Anode exhaust gas line 9 Cathode exhaust gas 10 Combustion exhaust gas 13 Air preheater 14 Condenser 15 Steam separator drum 16 Low temperature blower 17 Air 18 Cathode circulation line 21 Turbine compressor 23 Steam 26 Raw material gas 27 Raw material blower 28 High temperature blower 29 Air blower 34 Cathode exhaust gas line 50 Hot air generator 56 for starting gas Exhaust gas 57 Starting heater 59 Cathode branch line 61 Fuel supply for reformer Valve An Anode Ca Cathode T Turbine C Air compressor Co Combustion chamber Re Reforming chamber

Claims (1)

(1) A fuel gas (1) obtained by adding steam (23) to a raw material gas (26) from a raw material blower (27) during a steady operation. Of the fuel cell (5), the anode gas (2) containing the reformed hydrogen is supplied to the anode (An) of the fuel cell (5), and the cathode gas (4) is supplied to the fuel cell ( Electric power is generated by supplying the cathode (Ca) of (5), and the cathode exhaust gas (9) from the cathode (Ca) is supplied to the cathode exhaust gas line (3).
4) via the turbine (T) of the turbine compressor (21)
And a part of the cathode exhaust gas (9) is led to the combustion chamber (Co) of the reformer (3) through the cathode branch line (59), and the anode exhaust gas (6) from the anode (An). ) Is introduced into the combustion chamber (Co) of the reformer (3) through the anode exhaust gas line (7) and burned, thereby serving as a heat source for reforming, and the combustion exhaust gas (10) from the reformer (3) is used. An air preheater (13) and a condenser (14) lead to a steam separator (15), and the turbine compressor (2)
1) The air compressor (C) and the turbine compressor (2)
1) A bypass line provided in the air line (51)
The air (1) from the air blower (29 ) in (30)
7) together with the combustion exhaust gas (10) and a part of the cathode exhaust gas (9), which have been pressurized by the low-temperature blower (16) through the steam separator (15), are heated to a high temperature through a cathode circulation line (18). A method for increasing the temperature of a molten carbonate fuel cell power generator at the time of startup in which a blower (28) supplies the cathode gas (4) to a cathode (Ca) of a fuel cell (5). In a state where the gas in the cathode circulation line (18) is circulated by driving the blower (28), the air (17) from the air blower (29) is supplied to the starting hot air generating furnace (50) and the raw material blower is supplied. The raw material gas (26) from (27) is supplied to a hot air generating furnace (50) for starting, and a high temperature exhaust gas (56) generated by combustion in the hot air generating furnace (50) for starting is supplied to a cathode circulation line ( 18)
The fuel cell is guided to a turbine (T) of a turbine compressor (21) via a starting heater (57) provided on the way to heat a gas circulated in the cathode circulation line (18). (5) is heated, and when the inlet and outlet temperatures of the fuel cell (5) become equal to or higher than the temperature at which the electrolyte is melted and the wet sealing can be performed, one of the air (17) from the air blower (29) is removed. Part of the low-temperature blower (1
6), an air preheater (13), a cathode circulation line (18), a high-temperature blower (28), a starting heater (5)
7), fuel cell (5), cathode exhaust gas line (3
4), reformer (3) via cathode branch line (59)
Of the raw material blower (2)
Part of the raw material gas (26) from 7) is supplied to the combustion chamber (Co) of the reformer (3) via the fuel supply valve (61) for the reformer, and the raw material gas (26) is supplied to the combustion chamber (Co). (26) is burned, and the temperature of the reformer (3) is increased. When the temperature of the reformer (3) reaches a required temperature at which reforming is possible, the starting hot air generating furnace (50) is used. The supply of the source gas (26) to the hot air generating furnace (50) is stopped while the air (1) is
7) The supply of the raw material gas (26) to the combustion chamber (Co) of the reformer (3) is stopped while the supply of the raw material gas (26) is stopped.
Air compressor (C) in the turbine compressor (21)
And the air (17) from the air blower (29) are cooled by the low-temperature blower (16) into the air preheater (13), the cathode circulation line (18), the high-temperature blower (28), and the starting heater (5).
7), fuel cell (5), cathode exhaust gas line (3
4), reformer (3) via cathode branch line (59)
And the raw material gas (26)
Reformer (3) of the reforming chamber to start the supply of the (Re), molten carbonate fuel cells, characterized in that the shift to the steady operation of the steam (23) was added fuel gas (1) to How to raise the temperature of the power generator at startup.