JPH10302820A - Fuel cell power generating facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generating facility capable of performing the functions of a high temperature recycling blower and an air blower which are independently needed up to now in a single blower to reduce cost, and making a starting heater necessary in starting small to furthermore reduce cost. SOLUTION: The power generating facility has cathode recycling lines 7a-7d for mixing a cathode exhaust gas 7 of a fuel cell with air 6 and circulating the mixture into a cathode inlet, a high temperature recycling blower 17b arranged in a cathode recycling line, and an air flow rate regulating valve 6a formed in an air line 6 for mixing to the cathode exhaust gas, and air supply amount is controlled with the air flow rate regulating valve, and the recycling amount of cathode gas is controlled with the high temperature recycling blower. A starting heater is arranged in a CO2 recycling line for supplying combustion exhaust gas passed through a reformer to the cathode inlet of the fuel cell is arranged, and N2 gas is circulated to the CO2 recycling line and heated with the starting heater for starting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel cell power generation facility using a molten carbonate fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have features that are not found in conventional power generation equipment, such as high efficiency and little impact on the environment, and are attracting attention as power generation systems following hydro, thermal and nuclear power. It is currently being researched and developed around the world. In particular, in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, as shown in FIG. 2, a reformer 10 for reforming a fuel gas 1 such as natural gas into an anode gas 2 containing hydrogen, The fuel cell 11 includes a fuel cell 11 that generates electricity from the anode gas 2 and the cathode gas 3 containing oxygen. The anode gas 2 produced by the reformer 10 is supplied to the fuel cell 11 and most of the anode gas 2 is formed in the fuel cell. After consumption, for example, 80%), it is supplied to the catalytic combustor 20 as the anode exhaust gas 4. In the catalytic combustor 20, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas are converted into the cathode exhaust gas 7.
, And becomes a high-temperature combustion gas, enters the heating chamber H of the reformer 10, and heats the reforming chamber Re to reform the fuel in the reforming chamber. The combustion exhaust gas 5 exiting the heating chamber H is supplied to the air preheater 13b.
After being cooled by the pressurized air 6, the air is pressurized by the CO ₂ recycle blower 17 c and merged with the pressurized air 6 preheated by the air preheater 13 b and supplied to the cathode gas 3. C
The O ₂ recycle blower 17c removes the CO generated in the reformer.
_{The two} gases are supplied to the cathode side of the fuel cell and used for the cathode reaction.

The cathode gas (cathode exhaust gas 7) partially reacted in the fuel cell is partially circulated upstream of the fuel cell by a high-temperature blower 17b, and the remaining part 7a is sent to a reformer for combustion. The remaining 7b is supplied as air, the pressure of the remaining 7b is recovered by the turbine compressor 12, and is discharged out of the system after heat recovery by the exhaust heat recovery device 19. In FIG. 2,
13a is a fuel preheater, 14 is a desulfurizer, 15 is a check valve, 1
6 is a heater, 17d is an air blower, and 18 is a hot air generator.

[0004]

In the above-mentioned molten carbonate fuel cell power generation equipment, high efficiency and cost reduction are the biggest issues for commercialization. Therefore, in the fuel cell power generation system shown in FIG. 2, high efficiency has already been improved by introducing high-moisture exhaust gas to the cathode of the stack (fuel cell 11), but further improvement in efficiency and cost reduction have been achieved. Requested.

[0005] The present invention has been made to meet such a demand. In other words, the main object of the present invention is to focus on the fact that the air blower is not used during power generation, but is one of the factors that increases plant costs by operating only when supplying air at the time of startup. It is an object of the present invention to provide a fuel cell power generation facility in which a single blower can fulfill the functions of a high-temperature recycle blower and an air blower, which can further reduce costs. Another object of the present invention is to provide a fuel cell power generation facility that can reduce the size of a starting heater required at the time of starting, thereby further reducing costs.

[0006]

According to the present invention, in a fuel cell power generation facility for supplying anode exhaust gas of a fuel cell to a reformer after combustion, the cathode exhaust gas of the fuel cell is mixed with air and supplied to the cathode inlet side. A cathode recycle line for circulation, a high-temperature recycle blower provided in the cathode recycle line, and an air flow control valve provided in an air line mixed with the cathode exhaust gas, and the supply air amount is controlled by the air flow control valve. The fuel cell power generation equipment is characterized in that the amount of cathode gas recycled is controlled by a high-temperature recycle blower.

According to the configuration of the present invention described above, the conventional air blower is omitted, and a high-temperature recycle blower is installed at that position. In addition, since an air flow control valve is provided in the air line that mixes with the cathode exhaust gas, the amount of air supplied to the fuel cell is controlled by this air flow control valve, and at the same time, the inside of the cathode recycling line is controlled by a high-temperature recycle blower. By controlling the total amount of gas circulating, the inlet temperature of the fuel cell can be adjusted. Therefore, the functions of the high-temperature recycle blower and the air blower can be performed only by a single high-temperature recycle blower, and the cost can be further reduced.

According to a preferred embodiment of the present invention, a CO ₂ recycling line for supplying combustion exhaust gas passing through a reformer to a cathode inlet side of a fuel cell, and a CO ₂ recycling line provided in the CO ₂ recycling line A blower and a start-up heater are provided, and the heater heats nitrogen gas in the CO ₂ recycle line.

With this configuration, N ₂ circulation is performed in the CO ₂ recycle line by the CO ₂ recycle blower at the time of start-up, and the N ₂ gas can use the N ₂ purge gas system (city gas line) used when the plant is stopped. .
Further, since the CO ₂ recycle line is provided with the heater, the gas flow rate in the CO ₂ recycle line is small, so that the startup heater can be reduced in size and cost can be reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In the drawings, common parts are denoted by the same reference numerals. FIG. 1 is an overall configuration diagram of a fuel cell power generation facility according to the present invention. In this figure, a high-temperature recycle blower 17b is arranged at a position of a conventional air blower, and is provided with an air blower (17 in FIG. 2).
d) is omitted. Cathode recycle lines 7a, 7b, 7c and 7d are provided so that the cathode exhaust gas 7 of the fuel cell 11 is mixed with the air 6 and circulated to the cathode inlet side by the high temperature recycle blower 17b. Flow control valve 9a and shut-off valve 9b
Is provided. Further, the air line 6 for mixing with the cathode exhaust gas is provided with an air flow control valve 6a and an orifice 6b. The flow control valve 9a, the shutoff valve 9b, and the air flow control valve 6a are controlled by an output command of the entire plant.

According to the above configuration, the air flow control valve 6a is provided in the air line 6 for mixing with the cathode exhaust gas 7, so that the air flow control valve 6a controls the amount of air supplied to the fuel cell 11. At the same time, the cathode recycling lines 7a to 7
The inlet gas temperature of the fuel cell 11 can be adjusted by controlling the total amount of gas circulating in d. This temperature is the temperature sensor T
x and can be monitored by the controller.
Therefore, the functions of the conventional high-temperature recycle blower and the air blower can be performed only by the single high-temperature recycle blower 17b, whereby the cost can be further reduced.

The fuel cell power generation system shown in FIG. 1 further includes CO ₂ recycle lines 5 a, 5 b, 5 for supplying the combustion exhaust gas passing through the reformer 10 to the cathode inlet side of the fuel cell 11.
c, the CO ₂ recycle blower 17c provided in the CO ₂ recycle lines 5b and 5c, and the heater 1 for starting.
6 is provided. With this configuration, by supplying the N ₂ gas from the N ₂ purge gas line 21 via a line 2 and 4 at startup, the CO ₂ recycle blower 17c via the CO ₂ recycle line 5a~5c and catalytic combustor 20 N ₂
Circulates, and at the same time, heater 1 of CO ₂ recycling line
6, the N ₂ gas can be heated to raise the temperature. Further, by providing a heater 16 in the CO ₂ recycle line, since the gas flow rate of CO ₂ recycle line is small, it either possible to reduce the cost and miniaturize the start-up heater.

Further, in the fuel cell power generation equipment shown in FIG. 1, the temperature of the combustion gas exiting the catalytic combustor 20 is detected by a temperature sensor Tx, and compressed air is mixed with the cathode exhaust gas so as to keep this temperature constant. It has become. Further, the rotation speed of the turbine compressor 12 and the amount of gas bypassing the turbine are controlled in accordance with the output command. Other configurations are the same as those of the conventional fuel cell power generation equipment shown in FIG.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0015]

As described above, the fuel cell power generation equipment of the present invention can perform the functions of the high-temperature recycle blower and the air blower, which were conventionally required independently, with a single blower. It has excellent effects such as cost reduction and downsizing of the starting heater required at the time of starting, whereby the cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel cell power generation facility according to the present invention.

FIG. 2 is an overall configuration diagram of a conventional fuel cell power generation facility.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Cathode gas 4 Anode exhaust gas 5 Combustion exhaust gas 5a, 5b, 5c Combustion exhaust gas line 6 Air line 6a Air flow control valve 6b Orifice 7 Cathode exhaust gas 7a, 7b, 7c, 7d Cathode exhaust gas line 8 Steam 10 Revision quality 11 fuel cell 12 turbine compressor 13a fuel preheater 13b air preheater 14 desulfurizer 15 check valve 16 heater 17a fuel blower 17b hot blower 17c CO ₂ recycle blower 17d air blower 18 hot air generator furnace 19 exhaust heat recovery device 20 catalytic combustor 21 N ₂ purge gas line

Claims (2)

[Claims] 1. A cathode recycling line for mixing a cathode exhaust gas of a fuel cell with air and circulating it to a cathode inlet side in a fuel cell power generation facility for supplying an anode exhaust gas of a fuel cell to a reformer after combustion. It has a high-temperature recycle blower provided in the line and an air flow control valve provided in the air line that mixes with the cathode exhaust gas. The amount of air supplied is controlled by the air flow control valve, and the amount of cathode gas recycled is a high-temperature recycle blower. A fuel cell power generation facility, characterized in that the fuel cell power generation facility is controlled by: 2. A combustion exhaust gas which has passed through the reformer includes a CO ₂ recycle line for supplying the cathode inlet side of the fuel cell, and a CO ₂ recycle blower and the start-up heater provided in the CO ₂ recycle line the fuel cell power plant according to claim 1, characterized in going on, to heat the nitrogen gas CO ₂ recycle line by the heating device.