JPH0552036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a power generation device using a fuel cell.

[Background of the invention]

Fuel cells have the characteristics of high energy conversion efficiency, few environmental problems, and the ability to freely select the output scale due to the modular configuration, and are seen as a promising power generation method next to hydropower, thermal power, and nuclear power. There is.

Solid electrolyte fuel cells are the third generation fuel cells following the phosphoric acid type and molten carbonate type, and development is being promoted in Japan under the Moonlight Project.
It is being developed in the United States by Westinghouse. Regarding these situations, for example, IEEJ Technical Report (Department) No. K1 (Prospects of Fuel Cells)
It is described in detail in the Institute of Electrical Engineers of Japan (December 1982).

Regarding the power generation principle of solid oxide fuel cells,
For example, Prototype production and power generation test of high-temperature solid electrolyte fuel cells, Journal of the Society of High Temperature Studies (Volume 7, No. 5),
(September 1981) and others.

Regarding the principle of the solid oxide fuel cell mentioned above,
This will be explained next with reference to FIG. A solid electrolyte fuel cell is composed of a fuel electrode 1, an air electrode 2, and a solid electrolyte 3. For the fuel electrode 1, NiO, Co, or the like is used because it has high electronic conductivity, is stable in a reducing atmosphere, and does not react with the electrolyte. On the other hand, the air electrode 2 has high ionic conductivity as well as electronic conductivity, is chemically stable in an oxidizing atmosphere, and can match the thermal expansion of the electrolyte.
Ni-Al, LaCoO ₃ , SnO ₂ doped In ₂ O ₃ and the like are considered. In addition, the solid electrolyte 3 has an ionic transfer number close to 1, is physicochemically stable, and satisfies the conditions of not allowing gas to pass through, such as ZrO ₂ ,
Stabilizing substances such as ThO ₂ and CeO ₂ are available, but currently zirconia (ZrO ₂ ) stabilized with yttrium oxide (Y ₂ O ₃ ) is often used. This stabilized zirconia has a fluorite crystal structure and has oxygen ion conductivity proportional to the oxygen partial pressure due to lattice defects in oxygen atoms. This oxygen ion conductivity becomes noticeable at about 1000°C.

In order to operate the battery, a fuel 5 such as hydrogen or carbon monoxide is flowed on the fuel side, air 7 is flowed on the air side, and both electrodes are connected with a load 4. On the fuel side, the fuel 5 and oxygen ions 8 in the electrolyte 3 undergo the following reaction.

CO+O ^2- →CO+2e ^- H ₂ +O ^2- →H ₂ O+2e ^- Oxygen ions 8 conduct electricity in the electrolyte 3, and a shortage of oxygen ions 8 occurs on the electrical side, and the oxygen in the air 7 becomes O ₂ +4e ^- →DO ^2- , and this reaction causes the movement of electrons, causing a current 9 to flow from the air electrode 2 to the fuel electrode 1.

Note that unlike the phosphoric acid type, molten carbonate type, etc., the solid oxide type fuel cell has no restrictions on fuel components, and for example, natural gas or the like can be directly used as the fuel. That is, the temperature inside the fuel cell causes an internal rehoming reaction, and the exit fuel exhaust gas H ₂ ,
CO is produced. However, like other fuel cells, it is difficult to completely consume the supplied fuel and oxygen due to limitations such as current density and cell size.
Water and unreacted fuel remain in the exhaust fuel 6 on the fuel side,
Unreacted oxygen will remain in the exhaust gas on the air side. Further, the decrease in cell efficiency due to polarization 7a becomes heat accompanying the reaction, which results in an increase in the temperature of both or one of the gases on the fuel side and the air side, unless a special cooling mechanism or medium is used.

The open circuit voltage E, which is the theoretical electromotive force, is determined by the Nernst equation based on the oxygen partial pressure P _O2 on the fuel side and air side.
It is expressed as the ratio of

E=RT/4FlnP _O2 (air side)/P _O2 (fuel side) where R is the gas constant, T is the operating temperature, and F is the Faraday constant.

The operating temperature of solid electrolyte fuel cells must necessarily be high in order to improve ionic conductivity, and the idea of utilizing the high exhaust heat temperature for power generation plants has been proposed, for example, in the Power Source Journal. (Journal of Power Source) 10 (1983)
89−102 Technical problems of high temperature molten salt fuel cells (High
−Temperature Solid Oxide Fuel Cell−
Technical Status) etc.

FIG. 2 cites an example discussed in the above-mentioned literature, and will be explained below with reference to FIG.

Fuel 25 passes through fuel preheater 10 and enters solid electrolyte fuel cell main body 11 . On the other hand, air 26 passes through the air preheater 13 from the fan 22 and enters the solid electrolyte fuel cell main body 11. Solid electrolyte fuel cell 1
Non-fuel and exhaust air 28 that generated electricity 31 in 1
is burned in the afterburner 12, and a portion is introduced into the fuel preheater 10 to preheat the fuel and then discharged to the outside from the chimney 24. The remaining fuel exhaust gas 28 passes through the waste heat boiler 15, the feed water heater 16, and the air preheater 13 before being discharged to the outside from the chimney 24. The feed water heater 16 heats the feed water 29, and the heated feed water becomes superheated steam 30 in the waste heat boiler 15 and drives the steam turbine 19. The steam turbine 19 drives a generator 21 to generate electricity, and the steam 30 that drove the steam turbine 19 is condensed in a condenser 20, enters a deaerator 17, and after being deaerated, enters a water supply pump 18.

At startup, the auxiliary combustor 14 opens a valve 23a to supply fuel 25, operates a fan 22 to supply air 26, opens a valve 23b to introduce combustion gas into the fuel reserver 10, and drains the remaining fuel. Use as a heat source.

In such a solid oxide fuel cell power generation system, the heat generated by the electrochemical reaction in the solid oxide fuel cell and the unreacted fuel in the solid oxide fuel cell are converted into heat, and only in the form of heat is used to generate steam and drive a steam turbine. A major drawback is that solid electrolyte fuel cells cannot take full advantage of their high operating temperature and good exhaust heat quality.

Next, regarding molten carbonate fuel cells, see IEEJ Technical Report (Department) No. 141 (Fuel Cell Prospects),
It is described in detail in the Institute of Electrical Engineers of Japan (December 1982). First, the principle of a molten carbonate fuel cell will be explained with reference to FIG. The molten carbonate fuel cell is composed of a fuel electrode 41, an electric electrode 42, and an electrolyte 43. The fuel electrode 41 is made of NiCo, Ni, etc.
The electrode plate uses a porous Ni alloy and is sintered in a reducing atmosphere. Additionally, the electrode plates are reinforced by embedding Ni or SUS nets and thin wires. On the other hand, the air electrode 42 is made of NiO, and Li is added to improve its conductivity. Also, similar to the fuel electrode 41, a metal net is embedded and reinforced.

As a general characteristic of an electrolyte, when two or more types of alkali carbonates are mixed, the melting point decreases, so a mixed carbonate is used as the electrolyte 43, and generally (Li ₂ CO ₃ ) _0.62 (K ₂ CO ₃ ) _0.38 is used. It is being Since this electrolyte 43 becomes liquid at an operating temperature of 600 to 700 DEG C., it may seep into the electrode pores or flow out to the outside of the battery, and a matrix type or paste type is used to prevent electrolyte fluidity.

The fuel cell configured as described above also has drawbacks such as cracking in the electrolyte plate due to temperature changes during startup and shutdown.

Next, the power generation principle of fuel cells will be explained. Fuel electrode 4
Hydrogen 45 is supplied to the air electrode 42, a mixed gas 47 of air and carbon dioxide is supplied to the air electrode 42, and both electrodes are placed under a load 4.
Tie with 4. At the air electrode 42, oxygen and carbon dioxide gas 47 in the air receive electrons from an external circuit to become carbonate ions 48, which move through the electrolyte 43 to the fuel electrode 41 and react with hydrogen 45 to produce carbon dioxide gas and water 46. do. The reaction formula at this time is Air electrode: O ₂ +2CO ₂ +4e ^- →2CO ₃ ^2- Fuel electrode: 2H ₂ +2CO ₃ ^2- →2CO ₂ +2H ₂ O+4e ^- , and from both equations, the overall reaction is as follows. .

2H ₂ +O ₂ →2H ₂ O Due to the above reaction, electrons move, and a current 49 flows from the air electrode 42 to the fuel electrode 41.

Next, a molten carbonate fuel cell system will be explained with reference to FIG. Natural gas fossil fuel 6
3 is preheated by a heat exchanger 62 through a fan 61 and then supplied to the fuel reformer 50. At this time, fuel 6
3 contains sulfur, the reforming catalyst is easily poisoned, and the fuel electrode 53 is also easily affected by sulfur impurities, so the reformer 50 and fuel cell 5
It is necessary to install a desulfurization device 51 between the two bodies to remove the sulfur component to 1 ppm or less.

On the other hand, air is mixed with fuel electrode exhaust gas in advance and passed through a catalytic combustor 56 to convert remaining hydrogen and carbon monoxide into water and carbon dioxide gas, and a mixed gas 67 of air and carbon dioxide is supplied to the air electrode 54. Supplied. The high-temperature gas discharged from the fuel cell 52 is used as a heat source for driving the steam turbine 59, that is, serves as the bottoming cycle of the combined power generation system. The power generation efficiency of the battery itself and the bottoming cycle is expected to be approximately 50-60%. On this occasion,
In order to improve the overall efficiency of fuel cell power generation systems, efforts are being made to improve the fuel cell itself and review these subsystems, but the current situation is that high-quality energy cannot be used effectively.

If the target value of overall efficiency is 80%, reformer 5
Another problem is that the heat source necessary for operating the reformer 50 cannot be efficiently obtained from the fuel cell 52 because the fuel cell 52 and the fuel electrode 53 are not thermally adjacent to each other. .

There are also other problems, such as the relatively low temperature heat sources discharged from the steam turbine and various peripheral devices that are not effectively recovered.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and
The purpose of the present invention is to provide a highly efficient fuel cell power generation device in which an auxiliary system around a fuel reformer is omitted.

[Summary of the invention]

The basic principle of the present invention created to achieve the above object will be described below.

The present invention replaces the fuel reformer in the conventional molten carbonate fuel cell power generation system with a solid oxide fuel cell that utilizes a high temperature of approximately 1000°C, thereby effectively utilizing high quality thermal energy. , auxiliary equipment around the fuel reformer (e.g. desulfurizer,
This is a highly efficient fuel cell power generation system that can simplify the system by eliminating the need for a reformer, carbon monoxide shift converter, etc. In other words, if we pay attention to the fact that the operating temperatures of the fuel reformer and solid oxide fuel cell are almost the same, the purity of the fuel components is not very strict.
Moreover, by using the electric power generated from a solid oxide fuel cell that involves an internal reforming reaction, it is possible to construct a fuel cell power generation system that is much more efficient than the energy utilization rate of conventional fuel reformer heat recovery. .

In order to achieve the above object based on the above principle, the fuel cell power generation device of the present invention is provided with a fuel preheater and an air preheater, and the fuel preheated by the above fuel preheater and the air preheated by the air preheater. A solid oxide fuel cell is provided which performs an electrochemical reaction using the molten air, and a molten salt fuel cell is provided separately from the above, and the fuel exhausted from the solid oxide fuel cell is transferred to the molten salt fuel cell. In addition to supplying the fuel to the fuel electrode side of the salt fuel cell, the exhaust gas produced by burning the fuel discharged from the fuel electrode side of the molten salt fuel cell by the air exhausted from the solid oxide fuel cell is fused into the molten salt fuel cell. It is characterized in that it is configured to be supplied to the air electrode side of a salt-type fuel cell to cause an electrochemical reaction.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG. First, the configuration of the fuel cell system will be schematically shown. A fuel preheater 71, a solid oxide fuel cell 72, a compressor (a) 76, and a molten carbonate fuel cell 75 are installed according to the flow of the fuel 80. Meanwhile, according to the flow of air 81, the compressor (b)
77, air preheater 73, solid electrolyte fuel cell 7
2. Catalytic combustor 74, molten carbonate fuel cell 7
5, and a turbine 78 are installed. In addition,
Compressor (a) 76 and (b) 77 and turbine 78
are configured to rotate coaxially.

Next, the operating principle of this system will be explained. First, a fuel 80 such as natural gas is supplied to the fuel electrode of the solid oxide fuel cell 72 through the fan 86 .

In the steady state of operation, the fuel 80 is supplied to the fan 86.
In the fuel preheater 71 installed between the fuel cell 72 and the fuel cell 72, the fuel 80a before reaction and the fuel 8 after reaction are heated.
Gas-to-gas heat exchange is performed with the solid oxide fuel cell 72, and the temperature is raised to 800 to 1000° C., which is the operating temperature of the solid oxide fuel cell 72, and the fuel is supplied from the fuel inlet manifold 72a. On the other hand, air 81 is pressurized by compressor (a) 77 and supplied into solid oxide fuel cell 72 . In the case of air 81, as in the case of fuel 80, gas-gas heat exchange is performed with the air 81a, 81b before and after the reaction in the air preheater 73, and similarly, the fuel cell 7
2 is heated to 800 to 1000°C and supplied from the electric inlet manifold 72c. At this time, the fuel 80 generates hydrogen in the solid oxide fuel cell 72 while undergoing an internal reforming reaction, and this hydrogen and oxygen in the air 81 undergo an electrochemical reaction, resulting in the movement of oxygen ions (O ^2- ). A direct current flows, producing an electrical output 83a. Therefore, the fuel 80b discharged from the solid oxide fuel cell 72 undergoes heat exchange in the fuel preheater 71 in a state in which some hydrogen has been consumed, and is then pressurized by the compressor (d) 76 and supplied to the molten carbonate fuel cell 75. be done. On the other hand, the air 81b discharged from the solid oxide fuel cell 72 consumes a certain amount of oxygen and undergoes heat exchange in the air preheater 73.
It is combusted in the catalytic combustor 74 together with the fuel discharged from a, producing air and carbon dioxide, which are supplied to the air electrode 75b of the fuel cell 75. At this time,
In the molten carbonate fuel cell 75, the hydrogen in the fuel 80 and the oxygen and carbon dioxide in the mixed gas undergo an electrochemical reaction, and a current flows due to the movement of carbonate ions CO ₃ ^2- , producing a DC electrical output 83b. . At this time, the DC voltages generated in the solid oxide fuel cell 72 and the molten carbonate fuel cell 75 are both converted to AC via an inverter. here,
High-temperature gas discharged from the air electrode 75b of the molten carbonate fuel cell 75 is guided to the turbine 78 to generate electricity. At this time, the drive shafts of compressor (a) 76, compressor (b) 77, and turbine 78 are coaxial.

The power generation device of the above embodiment has a simple configuration in which the conventional fuel reformer and auxiliary system are omitted and a solid oxide fuel cell 72, a fuel preheater 71, and an air preheater 73 are installed instead. . In this embodiment, each preheater 71, 73 and the solid oxide fuel cell 72 main body are shown as separate structures, but when the present invention is implemented, these constituent members are limited to separate devices. Instead, both preheaters 71, 7
An integral structure in which 3 is housed within the solid oxide fuel cell 72 body is also conceivable. At this time, the solid oxide fuel cell 72 main body preheats the fuel 80 and air 81, and at the same time causes an internal re-forming reaction on the fuel side, so that the fuel 80 is necessary for the electrochemical reaction within the fuel cell 72 main body. Although it has a simple structure, it is an extremely important system because it can easily achieve the various conditions necessary for fuel cell reactions, such as generating hydrogen. Conventionally, there have been methods to generate hydrogen by installing a fuel reformer, or to create an internal reforming reaction by incorporating an active catalyst into the passage on the fuel electrode side of the main body of the molten carbonate fuel cell 75, but the former method The method for producing hydrogen requires a complicated structure because of the recycling for heat recovery. Furthermore, the latter method of causing an internal reforming reaction has drawbacks such as a lack of reliability regarding the flow of gas within the passage.

Compared to these conventional technologies, when the solid oxide fuel cell 72 described above is installed, assuming that the inside of the conventional refohmer structure is replaced with a solid oxide fuel cell, the high-temperature thermal energy in the refohmer is separately generated. There is no need to recycle the heat to the heat recovery system, and the main unit itself directly generates electrical output, so the system surrounding the fuel reforming system is extremely simplified, and the overall efficiency of the fuel cell power generation system is extremely high. Become. At this time, fuel 80
It is not necessary to use a highly pure fuel, and most gaseous fuels such as natural gas or lime gasified gas can be used.

On the other hand, the air 81 supplied to the solid oxide fuel cell 72 supplies oxygen for the electrochemical reaction and also serves to cool the reaction generated heat generated by the electrochemical reaction within the solid oxide fuel cell 72 body. At this time, assuming that the pressure ratio of the compressor (b) 77 is 10, the high temperature and high pressure air 81a
is approximately 300 to 400℃, and solid oxide fuel cell 7
Before being supplied to the solid oxide fuel cell 72 main body, the air preheater 73 exchanges heat with the fuel cell outlet air 81b for removing generated heat and supplies the air 81a at approximately 700°C. This cooling has the advantage of reducing thermal stress on the main body structure of the fuel cell 72 and making effective use of the heat recovered from the main body.

Here, both the hydrogen in the fuel 80 and the oxygen in the air 81 are consumed in fixed amounts within the solid oxide fuel cell 72 and supplied to the molten carbonate fuel cell 75. However, since the fuel 80 is accompanied by an internal reforming reaction in the solid oxide fuel cell 72, the fuel utilization rate is not so high. That is, the fuel electrode 75a of the molten carbonate fuel cell 75 is
supplied to Similarly, the air 81 is not only supplied as an electrochemical reaction within the solid electrolyte fuel cell 72, but also acts as cooling air, so the air utilization rate is not so high, that is, a state where the residual amount of oxygen is high. Then, it is supplied to the air electrode 75b of the molten carbonate fuel cell 75 via the catalytic combustor 74. Therefore, in the solid oxide fuel cell 72, the fuel utilization rate and the air utilization rate are considered to be about 50% or less, and both contain unreacted fuel (for example, hydrogen,
or oxygen) is supplied into the molten carbonate fuel cell 75 and consumed, and it is thought that the fuel utilization rate and air utilization rate will eventually reach approximately 90%. From the above points, the fuel cell power generation device of this example effectively utilizes hydrogen in the fuel and oxygen in the air, and also uses the thermal energy necessary for the electrochemical reaction within the fuel cell body, and the It is an extremely high-efficiency power generation device that can recover heat without wastefully recycling generated heat and other thermal energy. Note that the low-quality thermal energy discharged from the air electrode 75b of the molten carbonate fuel cell 75 is recovered by generating electricity with the turbine 78. In this case, solid oxide fuel cells (1000℃), molten carbonate fuel cells (650℃
℃), a phosphoric acid fuel cell (200℃) and taking advantage of the lower operating temperature, a phosphoric acid fuel cell is installed in place of a turbine, and the waste fuel discharged from the molten carbonate fuel cell, It is also possible to configure a three phase type fuel cell power generation system using exhaust air as fuel for phosphoric acid and air. At this time, it is thought that the power generation device will be more efficient than the amount of power generated by turbine drive. In this case, an important technical challenge is to improve the fuel and air utilization efficiency in phosphoric acid fuel cells.

FIG. 6 shows a different embodiment from the above, and the same drawing reference numbers as in the previous example (FIG. 5) indicate the same components as in the previous example.

In this embodiment, a fuel preheater 84 is installed on the exhaust side of the turbine 78, and the low-quality thermal energy exhausted from the turbine 78 is recovered by the fuel preheater 84 before flowing into the original fuel preheater 71. , is configured to improve the efficiency of heat recovery in this power generation device.

Further, another embodiment of the present invention will be explained with reference to FIG. In this example, before the air 81 supplied to the solid oxide fuel cell 72 flows into the air preheater 73, it passes through the molten carbonate fuel cell 75, cools the fuel cell 75, and at the same time uses cooling heat to cool the fuel cell 75. By preheating the air, the heat generated within the molten carbonate fuel cell 75 is recovered, thereby improving the efficiency of heat recovery in the power generating apparatus.

FIG. 8 shows a further different embodiment. In this example, a fuel preheater 71 and an air preheater 73 are installed in a fuel path and an air path that are supplied to the solid oxide fuel cell 72, respectively.
In the fuel preheater 71, the fuels 80a and 80 before and after the reaction are
Since b performs gas-gas heat exchange, indirect heat exchange by the tube is removed, and fuels 80a and 80 with different gas compositions before and after reaction are generated in the fuel preheater 71.
Perform direct heat exchange of b. Here, the direct heat exchange method is not an indirect heat exchanger in which a large number of heat transfer tubes are arranged in the body like the conventional multi-tube heat exchanger,
It is a direct gas-gas contact heat exchanger in which all these heat transfer tubes are removed and high temperature fluid and low temperature fluid are directly mixed within the body. This type has the advantage that when the two fluids to be heat exchanged have the same components, it is easy to separate the components, and since there is no heat exchanger tube, the heat exchange performance is high and it is compact. In this case, the hydrogen generated by the internal reforming reaction within the solid oxide fuel cell 72 diffuses into the unreacted fuel 80, resulting in a slight decrease in fuel reforming performance. It is necessary to install an auxiliary fuel reformer 87 between the fuel and the fuel cell 76. Similarly, the air preheater 73 also uses gas before and after the reaction.
Create a direct heat exchanger by removing the indirect tube to perform direct gas heat exchange. In this case, the compositions of the air 81a and 81b before and after the reaction for heat exchange are the same, and there is an advantage that the change in gas composition is less severe than in the fuel preheater 71. As described above, by using the fuel preheater 71 and the air preheater 73 as gas-gas direct contact type heat exchangers, by mixing and heat-exchanging the two fluids, gas and gas, directly in the heat exchangers. The compositions of the fuel and air to be supplied can be made almost uniform before and after the reaction, and at the same time, each of the preheaters 71 and 73 has an extremely compact structure.

〔Effect of the invention〕

As described in detail above, the fuel cell power generation device of the present invention has excellent practical effects in that the auxiliary system around the fuel reformer is significantly simplified and the efficiency is high compared to conventional devices.

[Brief explanation of drawings]

Figure 1 is a diagram of the principle of a conventional solid oxide fuel cell, Figure 2 is a system diagram showing a conventional solid oxide fuel cell power generation device, Figure 3 is a diagram of the principle of a conventional molten carbonate fuel cell, and Figure 3 is a diagram of the principle of a conventional solid oxide fuel cell. FIG. 4 is a system diagram showing a conventional molten carbonate fuel cell power generation device, and FIG. 5 is a system diagram showing a fuel cell power generation device which is an embodiment of the present invention.
FIG. 6 is a system diagram showing a fuel cell power generation device which is another embodiment of the present invention, FIG. 7 is a system diagram showing a fuel cell power generation device which is still another embodiment of the present invention, and FIG. 8 is a system diagram showing a fuel cell power generation device which is another embodiment of the present invention. FIG. 2 is a system diagram showing a fuel cell power generation device which is a further different embodiment of the invention. 1...Fuel cell, 2...Air electrode, 3...Solid electrolyte, 4...Load, 5...Fuel, 6...Water, 7
...Air, 8...Oxygen ion, 9...Current, 10
... Fuel preheater, 11 ... Solid electrolyte fuel cell,
12...Afterburner, 13...Air preheater, 1
4... Auxiliary combustor, 15... Waste heat boiler, 16...
... Feed water heater, 17 ... Deaerator, 18 ... Water pump, 19 ... Steam turbine, 20 ... Condenser, 21 ... Generator, 22 ... Forced draft fan,
23...Valve, 24...Chimney, 25...Fuel,
26...Air, 27...Preheated fuel gas, 28...
Exhaust gas, 29...Water supply, 30...Superheated steam, 31
... Electric output, 41 ... Fuel electrode, 42 ... Air electrode, 43 ... Electrolyte, 44 ... Load, 45 ...
Hydrogen, 46...Hydrogen, carbon dioxide, and water, 47
... Mixed gas of air and carbon dioxide, 48 ... Carbonate ions, 49 ... Electric current, 50 ... Fuel reformer, 51
... Desulfurization equipment, 52 ... Molten carbonate fuel cell,
53... Fuel electrode, 54... Air electrode, 55...
Electrolyte, 56... Catalytic combustor, 57... Gas-liquid separator, 58... Compressor, 59... Turbine,
60... Generator, 61... Fan, 62... Heat exchanger, 63... Fuel, 64... Air, 65...
Water, 66...Steam, 67...Mixed gas of air and carbon dioxide, 68...Inverter, 69...Electric output, 71...Fuel preheater, 72...Solid oxide fuel cell, 72a...Fuel inlet Manifold, 7
2b... Fuel outlet manifold, 72c... Air inlet manifold, 72d... Air outlet manifold, 73... Air preheater, 74... Catalytic combustor, 75... Molten carbonate fuel cell, 75a...
Fuel electrode, 75b...air electrode, 75c...electrolyte, 75d...fuel space, 75e...air space,
76……Compressusa (a), 77……Compressusa
(b), 78...turbine, 79...generator, 80...
...Fuel, 81...Air, 82...Exhaust gas, 83
... Electric output, 84 ... Fuel preheater, 85 ... Air preheater and cooler, 86 ... Fan, 87 ... Auxiliary fuel reformer.

Claims (1)

[Scope of Claims] 1. A solid electrolyte fuel that is provided with a fuel preheater and an air preheater and performs an electrochemical reaction with the fuel preheated by the fuel preheater and the air preheated by the air preheater. A battery is provided, and a molten salt fuel cell is provided separately from the above, and the fuel exhausted from the solid electrolyte fuel cell is supplied to the fuel electrode side of the molten salt fuel cell, and the solid electrolyte The exhaust gas obtained by burning the fuel discharged from the fuel electrode side of the molten salt fuel cell by the air exhausted from the molten salt fuel cell is supplied to the air electrode side of the molten salt fuel cell to cause an electrochemical reaction. 1. A fuel cell power generation device characterized in that it is configured to perform. 2. A compressor that pressurizes the air supplied to the solid oxide fuel cell, a compressor that pressurizes the fuel exhausted from the solid oxide fuel cell and supplied to the molten salt fuel cell, and and an expander driven by oxidant exhaust gas discharged from the air electrode side of the fuel cell, and both compressors are configured to be rotationally driven by the expander. A fuel cell power generation device according to claim 1. 3. The means for burning fuel using the air exhausted from the solid oxide fuel cell and supplying the exhaust gas to the molten salt fuel cell is a method for burning fuel using the air exhausted from the solid oxide fuel cell and supplying the exhaust gas to the molten salt fuel cell. The fuel cell power generation device according to claim 1 or 2, characterized in that the unreacted fuel is combusted by the exhaust air of the solid oxide fuel cell in a catalytic combustor. 4. The above-mentioned expander has, in addition to a fuel preheater installed to preheat the fuel supplied to the solid oxide fuel cell, a fuel preheater installed on the exhaust side to recover low-quality thermal energy discharged from the expander. The fuel cell power generation device according to claim 2, characterized in that it is equipped with a fuel preheater. 5 The molten salt fuel cell is a molten carbonate fuel cell, and the air that is supplied from the air compressor to the air electrode side of the solid oxide fuel cell flows into the air preheater. The claim is characterized in that the fuel cell is fed into the molten carbonate cell to cool the main body of the fuel cell and preheat the air, thereby improving heat recovery efficiency. The fuel cell power generation device according to item 2. 6. The air preheater performs gas-to-gas direct heat exchange between the air supplied from the compressor and the air discharged from the air electrode side of the solid oxide fuel cell.
3. The fuel cell power generation device according to claim 2, which is a preheater in which an indirect tube in a heat exchanger is removed. 7 The fuel preheater described above performs gas-to-gas direct heat exchange between the fuel supplied from the fan and the fuel discharged from the fuel electrode side of the solid oxide fuel cell, so the indirect tube in the heat exchanger is removed. Claim 1, characterized in that the preheater is a preheater, and an auxiliary fuel reformer is provided on the outlet side of the preheater that feeds gas to the fuel electrode side of the molten carbonate fuel cell. The fuel cell power generation device according to item 6.