JP3331569B2 - Fuel cell generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power generator having a pressure difference adjusting device for adjusting a pressure difference between a pressure inside a storage container of a fuel cell and a cathode.

[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 have attracted attention as power generation systems following hydro, thermal and nuclear power. Collected and are currently being studied in earnest in countries around the world.

FIG. 2 is a diagram showing an example of a power generation facility using a molten carbonate fuel cell using natural gas as a fuel. In FIG. 1, a power generation facility includes a reformer 10 for reforming a fuel gas 1 in which natural gas and steam are mixed into an anode gas 2 containing hydrogen, a cathode gas 3 containing oxygen, and an anode gas 2 containing hydrogen. And a fuel cell 20 that generates electricity from the fuel cell. The anode gas 2 produced by the reformer 10 is supplied to the fuel cell 20 and most of the anode gas 2 is consumed in the fuel cell 20 to become the anode exhaust gas 4, and the fuel is burned. It is supplied to the combustion chamber Co of the reformer 10 as a use gas.

[0004] In the reformer 10, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas 4 are burned in a combustion chamber Co to generate high-temperature combustion gas. After heating, the fuel gas 1 passing through the inside of the reformer 10 is reformed to be the anode gas 2. The combustion exhaust gas 5 that has exited the reformer 10 merges with the air 6 to become the cathode gas 3, and the cathode gas 3 partially reacts in the fuel cell 20 to become the high-temperature cathode exhaust gas 7, which compresses the air 6. After the power is recovered by the turbine compressor 40, the heat energy is further recovered by a waste heat recovery steam generator (not shown) and discharged outside the system.

As shown in FIG. 3, the molten carbonate fuel cell has a thin plate-shaped electrolyte plate (tile) 61 sandwiched between plate electrodes of a fuel electrode (anode) 62 and an air electrode (cathode) 63. (Single cell) 64, the fuel cell is maintained at about 650 ° C., an anode gas containing hydrogen is supplied to the anode side, and a cathode gas containing oxygen is supplied to the cathode side. It generates electricity. However, the voltage is low (0.8 V
Therefore, the battery is practically used as a battery (stack) that is stacked in multiple stages via a conductive bipolar plate (separator) 65. Further, such fuel cells are typically stored in a containment vessel 22 to increase efficiency and reduce the size of the device, and are operated under pressure.

[0006] The electrolyte plate 61 (tile) of the fuel cell is a ceramic powder sintered body in which an electrolyte is infiltrated by a capillary phenomenon. Sealing and gas sealing between the storage container 22 and the fuel cell 20 are performed. The performance of the seal due to such wetting (wet seal) is easily affected by the operation state of the fuel cell 20, and gas may leak even with a very small pressure difference (for example, 400 mmAq). Due to such gas leakage, for example, when the anode gas 2 and the cathode gas 3 are mixed, the anode gas 2
The hydrogen in the fuel may burn and destroy the fuel cell.
For this reason, the storage container 22 is filled with an inert gas, and the pressure of the anode gas 2 and the cathode gas 3 is balanced with each other so that these gases do not leak into the storage container 22 as shown in FIG.
The purge line 15 is provided to supply the nitrogen gas 8 as shown in FIG.

In order to fill the storage container 22 with nitrogen gas so that it can be constantly replenished, it is necessary to provide a nitrogen generator, a nitrogen heating device, a nitrogen supply line to the storage container, and the like. If provided, the power generation device becomes large, and the amount of nitrogen gas used increases. For this reason, it has been proposed to supply a part of the combustion exhaust gas 5 exiting the reformer 10 to the storage container 22.

[0008]

SUMMARY OF THE INVENTION In order to prevent the cathode gas 3 and the anode gas 2 from leaking from the fuel cell 20 into the storage container 22 and to prevent the cathode gas 3 and the anode gas 2 from being mixed in the cell, 22 and a differential pressure between the cathode or anode, between the cathode and anode,
Differential pressure control for maintaining the differential pressure is performed, but conventionally, appropriate differential pressure control has not been performed for the differential pressure between the storage container 22 and the cathode.

The present invention has been made in view of the above problems, and has as its object to provide a fuel cell power generator having a differential pressure adjusting device for adjusting a pressure difference between a pressure in a storage container and a cathode. .

[0010]

To achieve the above object, according to an aspect of, the present invention, a fuel cell that generates from the cathode gas containing oxygen (3) and an anode gas (2) containing hydrogen
(20) and a storage container (2 ) for storing the fuel cell (20).
2) and a modification in which the anode exhaust gas (4 ) of the fuel cell (20) is combusted with a part of the cathode exhaust gas (7) , and the heat is used to reform the fuel gas (1) containing water vapor into the anode gas (2). Exhaust (10) and cathode exhaust gas from fuel cell (20)
A circulation line (21) for circulating a part of (7) to the cathode
And a circulation line for the combustion exhaust gas (5) of the reformer (10)
And supplying (21) the exhaust gas supply line (13), from
The exhaust gas supply line.
Part of the combustion exhaust gas (5) of (13) is contained in the containment vessel (22).
In order to supply into the inside , the low temperature blower (35)
The position where the connection point of the line (37) and the air (6) merge
A storage container filling gas supply line from between the location connecting the up containment (22) (51), said containment vessel (22)
One is connected to the circulation line (21) in order to discharge the gas inside to the reformer (10) or the circulation line (21)
And the other is connected to the combustion chamber (Co) of the reformer (10).
And to have three-way valve containment gas discharge line having a (55) (53) detects the pressure of the cathode exhaust gas (7) of the pressure and the fuel cell of the containment vessel (22) (20), the The differential pressure is applied to the PCV filling gas supply line (5
1) and a differential pressure regulating device (56) that is regulated by flow regulating valves (52, 54) respectively provided in the gas discharge line (53) in the containment vessel, and the exhaust gas supply line (1).
3) the pressure at the outlet side of the low-temperature blower (35) provided in
Detects the pressure on the cathode inlet side of the circulation line (21)
And the pressure on the outlet side of the high-temperature blower (23)
A blower that controls the low-temperature blower (35) to be higher than the pressure
And a lower control device (39).
A fuel cell power generator is provided.

[0011]

[0012]

[0013]

According to the invention having the above construction, the flow rate adjusting valve (5 ) is connected to the containment vessel (22) through the containment vessel filling gas supply line (51).
A part of the combustion exhaust gas (5) is supplied via 2), and the flow control valve (54) is supplied from the gas discharge line (53) in the containment vessel.
Is discharged through. The differential pressure regulator (56) is a containment vessel
(22) and the pressure of the cathode exhaust gas (7) are detected, and the containment vessel filling gas supply line (51) and the containment vessel gas exhaust line (5 ) are set so that the differential pressure becomes a predetermined value.
3) Adjust the flow control valves (52, 54) . The differential pressure is such that the pressure in the containment vessel (22) is greater than the pressure in the cathode exhaust gas (7) ,
(3) is prevented from leaking into the storage container (22) .

[0014] a blower controller (39) by high so as cold blower than the pressure of the cathode inlet side of the outlet side pressure of the cold blower provided in the exhaust gas supply line (13) (35) circulation line (21) (35) Is controlled, the pressure of the combustion exhaust gas (5) supplied from the containment vessel filling gas supply line (51) to the containment vessel (22) is reduced
The pressure becomes higher than the pressure in (2) , and the combustion exhaust gas (5) can be supplied to the storage container (22) .

[0015]

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a fuel cell power generator according to the present invention. In this figure, the same components as those in FIG. 2 are represented by the same reference numerals. The fuel cell power generation equipment includes a reformer 10 for reforming a fuel gas 1 containing water vapor to an anode gas 2 containing hydrogen, and a fuel cell 20 for generating electricity from the anode gas 2 and the cathode gas 3 containing oxygen, The anode exhaust gas 4 discharged from the fuel cell 20 is supplied to the reformer 10 by the discharge line 12.
The combustion exhaust gas 5 is supplied to the cathode side C of the fuel cell 20 via the exhaust gas supply line 13 and the circulation line 21.

In FIG. 1, a fuel gas 1 is supplied to a fuel heater 11.
, And then supplied to the reformer 10. The reforming 10 includes a combustion chamber Co that burns the anode exhaust gas 4 and the cathode exhaust gas 7 that have exited the fuel cell 20, and a reforming chamber Re that reforms the fuel gas 1 by transferring heat from the combustion chamber Co. The reforming chamber Re is filled with a reforming catalyst, is heated by the high-temperature combustion gas generated in the combustion chamber Co, and reforms the fuel gas 1 into a high-temperature anode gas 2 containing hydrogen. And supplies it to the fuel cell 20. On the other hand, the combustion exhaust gas 5 whose temperature has been lowered by the heat release enters the circulation line 21 through the exhaust gas supply line 13, but is cooled in the exhaust gas supply line 13 by the air preheater 32, and the moisture is removed by the condenser 33 and the steam separator 34. Removed
It is pressurized by the low-temperature blower 35, mixed with the air 6, heated by the air preheater 32, and enters the circulation line 21. A bypass line 37 having a flow control valve 36 is provided between the outlet of the low-temperature blower 35 and the inlet of the condenser 33, and the discharge amount of the low-temperature blower 35 is adjusted.

A part of the cathode exhaust gas 7 drives the turbine of the turbine compressor 40 and is supplied to an exhaust heat recovery steam generator (not shown). The air 6 compressed by the turbine compressor 40 joins the flue gas 5 at the outlet of the low-temperature blower 35. The turbine compressor 40 is provided with a backup line 41 having an electric blower 42 and is used for backup when the capacity of the turbine compressor 40 is insufficient.

The fuel cell 20 comprises an anode side A through which the anode gas 2 passes and a cathode side C through which the cathode gas 3 passes. Hydrogen and carbon monoxide in the anode gas, oxygen in the cathode gas, and Electricity is generated from carbon by a chemical reaction.

Part of the cathode exhaust gas 7 is supplied to the air preheater 3
The exhaust gas is mixed with the combustion exhaust gas 5 and the air 6 heated in 2, and becomes the cathode gas 3, which is supplied to the cathode by the circulation line 21. The circulation line 21 circulates the cathode gas 3 by the high temperature blower 23.

The fuel cell 20 is stored in a storage container 22. A containment vessel filling gas supply line 51 is provided on the outlet side of the low-temperature blower 35 and connects the containment vessel 22 from a position between the connection position of the bypass line 37 and the position where the air 6 joins.
A part 9 of the combustion exhaust gas is supplied to the storage container 22 via the flow control valve 52. The storage container 22 is provided with a gas discharge line 53 in the storage container having a flow control valve 54 and a three-way valve 55, and one of the three-way valves 55 is connected to the circulation line 21 and the other is connected to the combustion chamber Co of the reformer 10. are doing.

A differential pressure adjusting device 56 is provided which detects the pressure of the storage container 22 and the pressure of the cathode exhaust gas 7 and adjusts the flow adjusting valves 52 and 54 so that the differential pressure becomes a predetermined value. The pressure difference between the pressure sensor 38 provided between the connection position of the bypass line 37 on the outlet side of the low temperature blower 35 and the connection position of the gas supply line for the containment vessel and the pressure sensor 24 provided on the cathode inlet side of the circulation line 21 is determined. A blower control device 39 for detecting and controlling the electric motor of the low-temperature blower is provided.

The operation of the components and lines around the storage container 22 and the low-temperature blower 35 configured as described above will be described. During operation of the fuel cell power generator, a part 9 of the combustion exhaust gas is supplied into the containment vessel 22 from the containment vessel filling gas supply line 51. Differential pressure adjusting device 5
6, when the pressure of the containment vessel 22 is higher than the pressure of the cathode exhaust gas 7 by a predetermined value or more, the flow control valve 52 is throttled to reduce the flow rate of a part 9 of the combustion exhaust gas, and the flow control valve 54 is opened and the three-way valve 55 The gas in the storage container 22 is discharged to the circulation line 21. When the pressure of the storage container 22 is not higher than the pressure of the cathode exhaust gas 7 by a predetermined value or more, the flow control valve 54 is closed and the flow control valve 52 is opened to adjust the pressure to the predetermined value.

The blower control device 39 controls the electric motor of the low-temperature blower 35 so that the outlet pressure of the low-temperature blower 35 becomes higher than the pressure on the cathode inlet side of the circulation line 21 by a predetermined value or more. The part 9 is supplied reliably.

The storage container 22 is provided with a detector (not shown), which constantly monitors the flammable gas in the storage container 22, and switches the three-way valve 55 when detecting hydrogen gas, carbon monoxide gas, methane gas or the like. Then, the gas in the storage container 22 is led to the combustion chamber Co of the reformer 10 where it is burned. This can prevent the combustible gas from burning in the storage container 22.

[0026]

As is apparent from the above description, the present invention detects the pressure of the containment vessel and the pressure of the cathode exhaust gas by the differential pressure adjusting device and adjusts the differential pressure. The differential pressure between them can be controlled to a predetermined value. Also, the blower control device controls the outlet pressure of the low-temperature blower to be higher than the cathode inlet pressure, so that the combustion exhaust gas can be reliably supplied into the containment vessel.
Further, since bypass lines are provided on the outlet side and the inlet side of the low-temperature blower, the flow rate of the combustion exhaust gas to the containment vessel can be adjusted.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram showing a configuration of a molten carbonate fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel gas 2 Anode gas 3 Cathode gas 4 Anode exhaust gas 5 Combustion exhaust gas 6 Air 7 Cathode exhaust gas 9 Part of combustion exhaust gas 10 Reformer 11 Fuel heater 12 Discharge line 13 Exhaust gas supply line 20 Fuel cell 21 Circulation line 22 Storage container 23 High-temperature blower 24, 38 Pressure sensor 32 Air preheater 33 Condenser 34 Steam separator 35 Low-temperature blower 36, 52, 54 Flow control valve 37 Bypass line 39 Blower controller 40 Turbine compressor 41 Backup line 42 Electric blower 51 Storage Container filling gas supply line 53 Containment container gas discharge line 55 Three-way valve 56 Differential pressure regulator Re Reforming chamber Co Combustion chamber A Anode side C Cathode side PX Pressure sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/04 H01M 8/06

Claims (1)

(57) [Claims] 1. A cathode gas containing oxygen(3)And hydrogen
Including anode gas(2)And fuel cell to generate electricity from(2
0)And the fuel cell(20)Storing the storage container(22)
And the fuel cell(20)Anode exhaust gas(4)The casor
Exhaust gas(7)Burning in some of the,Contains water vapor with its heat
Fuel gas(1)The anode gas(2)Reformer
(10)And the fuel cell(20)Cathode exhaust gas(7)
Line that circulates part of the water to the cathode(21)And
Porcelain(10)Combustion exhaust gas(5)The circulation line(21)
Exhaust gas supply line(13)When,Consisting offuel
In the battery power generator, the exhaust gas supply line(13)Combustion exhaust gas(5)One
Department of containment(22)Supply inFor low temperature blower
(35) Connection location of bypass line (37) on the exit side and empty
From the space where the gas (6) merges,
Connect up to 2)Containment vessel filling gas supply line(51)
When,Said Containment vessel(22)Gas in the reformer(10)Or
Circulation line(21)Discharge toOne is
(21), and the other is connected to the fuel of the reformer (10).
With three-way valve (55) connected to the firing chamber (Co)Case
Gas discharge line in the container(53)When,Said Containment vessel(22)Pressure and fuel cell inside(20)Mosquito
Sword exhaust gas(7)And the differential pressure is detected as described above.
Containment vessel filling gas supply line(51)And in the containment
Gas discharge line(53)Flow control provided for each
valve(52, 54)Differential pressure adjustment device(56)
When,Low-temperature blower provided in the exhaust gas supply line (13)
(35) and the pressure of the circulation line (21).
Detects the pressure on the inlet side of the sword and detects the outlet side of the high-temperature blower (23).
Low-temperature blow so that the pressure of
A blower control device (39) for controlling the blower (35); A fuel cell power generator, comprising: