JPH06215783A - Fuel cell-type electricity generating apparatus - Google Patents

Abstract

PURPOSE:To provide a fuel cell-type electricity generating apparatus which can lower the temperature of a gas to be sent by pressure by a recycle blower to make manufacture of recycle blowers easy and lower the manufacturing cost and at the same time which can lower the compressing motive power of a recycle blower and release heat from the middle parts of multilayered stacks. CONSTITUTION:A fuel cell 20 has a plate-like air flowing pathway E to heat air 6 to be supplied to a cathode C pinched between cells. Further, the fuel cell is provided with a heat-exchanger 22 to heat the air 6 by a cathode discharge gas 7 which comes out of the fuel cell 20 and a circulating line 11 in which a part 7b of the cathode discharge gas 7 cooled by the heat-exchanger 22 and a part 9 of a combustion discharge gas which comes out of a heat recovering apparatus 30 are mixed to mix the resulting gas mixture to the cathode gas 3 in the upper stream side of the fuel cell 20.

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, and more particularly to a fuel cell power generator using a molten carbonate fuel cell.

[0002]

2. Description of the Related Art Molten carbonate fuel cells have characteristics that conventional power generators do not have, such as high efficiency and little impact on the environment, and they are attracting attention as a power generation system following hydropower, thermal power, and nuclear power. Is currently being researched and developed all over the world. Particularly in a power generation facility using a molten carbonate fuel cell using natural gas as a fuel, a reformer 10 for reforming a fuel gas 1 such as natural gas into an anode gas 2 containing hydrogen as shown in FIG. A fuel cell 20 for generating electricity from an anode gas 2 and a cathode gas 3 containing oxygen is generally provided, and the anode gas produced by the reformer is supplied to the fuel cell, and most of the fuel gas in the fuel cell ( (For example, 80%), the combustion chamber C of the reformer 10 is used as the anode exhaust gas 4.
supplied to the o. In the reformer, combustible components (hydrogen, carbon monoxide, methane, etc.) in the anode exhaust gas are burned in the combustion chamber,
The reforming chamber Re is heated by the high-temperature combustion gas to reform the fuel flowing inside. The combustion exhaust gas 5 exiting the reforming chamber is subjected to heat recovery by the boiler 30, the moisture is removed by the condenser 33 and the steam separator 34, and a part thereof is mixed in the air 6, and this mixed gas is used as the anode gas 3 To join. As a result, carbon dioxide generated on the anode side of the cell enters the cathode gas 3 for the fuel cell via the combustion exhaust gas 5, and supplies carbon dioxide required for the cathode reaction of the fuel cell to the cathode side C. A part of the cathode gas 3 reacts in the fuel cell to become the cathode exhaust gas 7, a part of which is recirculated to the cathode inlet side, and the rest is recovered by the boiler 30 and discharged to the outside of the system.

[0003]

In the above conventional power generation equipment, the temperature of the cathode exhaust gas 7 is as high as 650 to 700 ° C., and therefore it is difficult to manufacture the recycle blower 40 for recirculating the cathode exhaust gas to the cathode inlet side. There was a point. That is, the blower for high temperature of 650 to 700 ° C. has a problem that it requires a special design, uses an expensive heat-resistant metal, has poor workability, and has a high manufacturing cost. Further, such a high temperature blower has a problem in that the compression efficiency of the blower is poor because a gas having a large capacity is pumped at a high temperature and the blower power is large. On the other hand, the fuel cell 20
Can increase the output by stacking a large number of cells (single cells) (higher stacking) (stacked fuel cells are called a stack). However, in the highly stacked stack, it is difficult to dissipate the reaction heat from the cells in the middle part.

The present invention was created to solve the above problems. That is, the first object of the present invention is to reduce the temperature of the gas pumped by the recycle blower, thereby facilitating the production of the recycle blower, lowering the production cost, and reducing the compression power of the recycle blower. To provide a battery power generator. Further, a second object of the present invention is to provide a fuel cell power generation device capable of radiating heat from an intermediate part of a highly stacked stack.

[0005]

According to the present invention, a reformer for reforming a fuel gas into an anode gas containing hydrogen, a fuel cell for generating electricity from an anode gas and a cathode gas containing oxygen, and And a heat recovery device for recovering heat from the combustion exhaust gas that has exited from the pouch, wherein the fuel cell has a flat air passage that is sandwiched between cells and that heats air supplied to the cathode. Further, a heat exchanger that heats air by the cathode exhaust gas that has exited the fuel cell, a part of the cathode exhaust gas that has been cooled by the heat exchanger, and a part of the combustion exhaust gas that has exited the heat recovery device are mixed. And a circulation line that supplies the cathode gas on the upstream side of the fuel cell.
According to a preferred embodiment of the present invention, a cathode gas line is provided which mixes the air heated through the flat air passage and the mixed gas in the circulation line to form the cathode gas. It is preferable to provide an exhaust gas mixing line for mixing the remainder of the cathode exhaust gas leaving the heat exchanger with the combustion exhaust gas.

[0006]

According to the above-mentioned structure of the present invention, a part of the cathode exhaust gas cooled by the heat exchanger and having a lowered temperature is mixed with a part of the still lower temperature combustion exhaust gas leaving the heat recovery device, and the upstream of the cathode. Since the gas is circulated to the side, the temperature of the gas pumped by the recycle blower becomes considerably lower than in the conventional case (for example, from about 650 ° C to about 400 ° C). Therefore, the recycle blower does not require special design, can use an inexpensive material that is not a heat-resistant metal, can be easily processed, and can reduce the manufacturing cost. Further, since the temperature of the gas fed under pressure by the recycle blower becomes low, the blower power also becomes small. Further, according to the configuration of the present invention, since the flat air flow path for heating the air supplied to the cathode is sandwiched between the cells of the fuel cell, the heat radiation from the cells in the middle part in the highly stacked stack is achieved. Can be done easily.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment 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, a fuel cell power generator according to the present invention includes a reformer 10 for reforming a fuel gas 1 into an anode gas 2 containing hydrogen, and a fuel cell 20 for generating power from an anode gas 2 and a cathode gas 3 containing oxygen. And a heat recovery device 30 for recovering heat from the combustion exhaust gas 5 exiting the reformer 10. Such a configuration is similar to that of the conventional fuel cell power generation device shown in FIG. The same parts as those in FIG. 2 are designated by the same reference numerals and used.

In FIG. 1, a fuel gas 1 such as natural gas is desulfurized by a desulfurizer (not shown), and then a fuel heater 1
2, is heated by the fuel preheater 12, and is supplied to the reformer 10. The reformer 10 has a combustion chamber Co in which the anode exhaust gas 4 discharged from the fuel cell 20 is burned by the air 6c.
And a reforming chamber Re that reforms the fuel gas by heat transfer from the combustion chamber. The reformer 10 includes a combustion chamber Co and a reforming chamber R.
It is preferable that the plate-type reformer is formed by stacking a plurality of e in a planar shape. The reforming chamber Re is filled with a reforming catalyst, and the high temperature combustion gas generated in the combustion chamber Co reforms the fuel gas 1 into the high temperature anode gas 2a containing hydrogen.
The high-temperature anode gas 2 a that has exited the reformer 10 is supplied to the fuel preheater 12, cooled by the fuel preheater 40, and supplied to the fuel cell 20. On the other hand, the combustion exhaust gas 5 (for example, about 800 ° C.) whose temperature has dropped due to heat radiation is supplied to the heat recovery device, that is, the boiler 30. The boiler 30 includes an evaporator 32 and a superheater 31, and heat is recovered from the high temperature combustion exhaust gas 5 to generate steam, and the combustion exhaust gas 5 to 200
Cool to 300 ° C. Then, the condenser 33 and the steam separator 34 remove water. The fuel cell 20 is composed of an anode side A through which the anode gas 2 passes, and a cathode side C through which the cathode gas 3 passes. It is designed to generate electricity by a chemical reaction. The fuel cell 20 may be a molten carbonate fuel cell. In addition, the anode exhaust gas 4 that has exited the fuel cell 20
Is supplied to the combustion chamber Co of the reformer 10 as described above.

The fuel cell 20 comprises a large number of cells (unit cells).
And a flat air passage E that is sandwiched between cells and that heats air (for example, 550 ° C.) supplied to the cathode (for example, 650 ° C.). In the figure, one cathode C, one anode A, and one air passage E are schematically shown, but in reality, a plurality of air passages E are provided between a plurality of cells (a combination of the cathode C and the anode A). Should be provided. Also, this air flow path E is
For example, like a plate fin heat exchanger, it has a thin flat plate shape, and air is allowed to flow between them. With such a configuration, in a highly stacked stack, heat can be easily radiated from the cells in the middle part.

The power generator according to the present invention further includes air 6 that is discharged from the fuel cell 20 as cathode exhaust gas 4 (for example, about 650).
Heat exchanger 22 which is heated by the heat exchanger 22 and a part 7 of the anode exhaust gas (for example, about 550 ° C.) cooled by the heat exchanger 22.
b and the flue gas discharged from the heat recovery device 30 (for example, about 50
(C) part 9 is mixed and mixed with the cathode gas 3 on the upstream side of the fuel cell 20 by a circulation line 11. A recycle blower 40 for pressure-feeding a mixed gas of anode exhaust gas and combustion exhaust gas is provided in the middle of the circulation line 11. With this configuration, a part of the cathode exhaust gas 7 cooled by the heat exchanger 22 and having a lowered temperature is mixed with a part of the combustion exhaust gas 5 having a still lower temperature which has exited the heat recovery device 30 and is circulated. The temperature of the gas pumped by is considerably lower than in the conventional case (for example, 4
About 00 ° C). Therefore, the recycle blower does not require special design, can use an inexpensive material that is not a heat resistant metal, can be easily processed, and can reduce the manufacturing cost. Further, the temperature of the gas pumped by the recycle blower becomes low, so the power of the blower also becomes small.

Further, there is provided a cathode gas line for forming the cathode gas 3 by mixing the air 6 heated through the heat exchanger 22 and the mixed gas in the circulation line 11.
That is, the cathode gas 3 entering the fuel cell is the air (eg, about 6) that has passed through the heat exchanger 22 and the flat air passage E.
50 ° C) and a mixed gas in the circulation line 11 (for example, about 40 ° C)
0 ° C.). As a result, the temperature of the cathode gas 3 entering the fuel cell is set to a temperature suitable for power generation (for example, about 550).
℃). Further, an exhaust gas mixing line for mixing the remainder 7a of the cathode exhaust gas that has exited the heat exchanger 22 with the combustion exhaust gas 5 is provided. That is, the remainder 7 a of the cathode exhaust gas that has exited the heat exchanger 22 is the evaporator 3 of the boiler 30.
2 is mixed with the combustion exhaust gas 5 at an intermediate position between the superheater 31 and the superheater 31. As a result, heat can be recovered from the remaining portion 7a of the cathode exhaust gas and steam can be generated.

[0012]

As described above, according to the configuration of the present invention, a part of the cathode exhaust gas cooled by the heat exchanger and having a lowered temperature is partially converted into a part of the lower temperature combustion exhaust gas discharged from the heat recovery device. Since it is mixed with and circulated, the temperature of the gas pumped by the recycle blower is considerably lower than that of the conventional gas (for example, about 400 ° C.). Therefore, the recycle blower does not require special design, can use an inexpensive material that is not a heat resistant metal, can be easily processed, and can reduce the manufacturing cost. Further, the temperature of the gas pumped by the recycle blower becomes low, so the power of the blower also becomes small. Further, according to the configuration of the present invention, since the flat air flow path for heating the air to be supplied to the cathode is sandwiched between the cells of the fuel cell, in the highly stacked stack, the heat radiation from the cells in the middle part is prevented. It can be done easily. Therefore, according to the present invention, the temperature of the gas pumped by the recycle blower is lowered, which facilitates the production of the recycle blower,
It is possible to reduce the manufacturing cost, reduce the compression power of the recycle blower, and provide a fuel cell power generation device that can radiate heat from the middle portion of a highly stacked stack.

[Brief description of 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.

[Explanation 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 12 Fuel Preheater 20 Fuel Cell 22 Heat Exchanger 30 Boiler 31 Superheater 32 Evaporator 33 Condenser 34 Steam separator 40 Recycle blower Re Reforming chamber Co Combustion chamber A Anode side C Cathode side

Claims (3)

[Claims] 1. A reformer for reforming a fuel gas into an anode gas containing hydrogen, a fuel cell for generating power from an anode gas and a cathode gas containing oxygen, and heat recovery from combustion exhaust gas leaving the reformer. In the fuel cell power generator including the heat recovery device, the fuel cell has a flat plate-shaped air flow path that heats air supplied to the cathode and is sandwiched between cells, and further, air is discharged from the fuel cell. A heat exchanger heated by the cathode exhaust gas, a part of the cathode exhaust gas cooled by the heat exchanger, and a part of the combustion exhaust gas discharged from the heat recovery device are mixed to form a cathode gas on the upstream side of the fuel cell. A fuel cell power generation device, comprising: 2. A cathode gas line for forming the cathode gas by mixing the air heated by passing through the flat air passage and the mixed gas in the circulation line. The fuel cell power generator according to claim 1. 3. The fuel cell power generator according to claim 1, further comprising an exhaust gas mixing line that mixes the remainder of the cathode exhaust gas that has exited from the heat exchanger with the combustion exhaust gas.