JPH1012255A - Fuel cell generating system and compound generating plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly enhance generating efficiency and operating efficiency, operability, etc., of a fuel cell, by effectively utilizing unreacted hydrogen discharged from a fuel cell main unit. SOLUTION: A fuel cell generating system 1 is provided with a fuel cell main unit 2 having a fuel electrode 2a and an air electrode 2b and a reforming means (120 reformer, 13: carbon monoxide transformer) producing reformed gas by reforming fuel gas 10, in this system, the following improving means is adopted: in a combustor 23, unreacted reformed gas discharged from the fuel electrode 2a, without reaction with air, is burned by air 21 to generate energy. This energy is utilized, a turbine main unit 20 is operated, generation is performed by a generator 22. Combustion gas, generated according to driving of the turbine main unit 20 to decrease a temperature, is fed to the reformer 12 through a discharge gas line 28, to be utilized as a reforming heat source for city gas.

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 generation system and a combined power generation plant that directly generate electric energy by electrochemically reacting hydrogen obtained from fuel gas and oxygen obtained from air, and more particularly to a combined power generation plant. The present invention relates to a fuel cell power generation system and a combined power generation plant in which unreacted hydrogen output from a fuel cell power generation system is effectively used to greatly improve power generation efficiency, fuel cell operation efficiency, and the like.

[0002]

2. Description of the Related Art A fuel cell power generation system is a power generation system that directly generates electric energy by an electrochemical reaction between hydrogen and oxygen. Such a fuel cell power generation system has high power generation efficiency despite its small capacity. In addition, it has advantages such as little impact on the environment, and is currently being actively developed as a new power generation system for the 21st century.

A fuel cell power generation system is roughly classified into a pressurized fuel cell power generation system in which fuel gas (natural gas, LPG, etc.) or air is pressurized and reacted, and a conventional fuel cell power generation system in which normal pressure fuel gas and air are reacted. Pressure fuel cell power generation system.

In the pressurized fuel cell power generation system, as described above, the fuel gas is pressurized by the compressor, and the air is further pressurized by the turbo compressor, whereby the electrochemical reaction in the fuel cell main body is favorably performed, and the power generation efficiency is improved. It has the advantage of increasing.

However, the necessity of the turbo compressor and the equipment for controlling the turbo compressor, etc., has led to an increase in the size of the entire system, and also has a problem that it is difficult to control the turbo compressor.

On the other hand, the normal pressure type fuel cell power generation system reacts fuel gas and air under normal pressure.
Since a simple system configuration can be realized without requiring a device such as a turbo compressor, research and development for practical use have been promoted in recent years.

FIG. 11 shows a schematic configuration of such a normal-pressure fuel cell power generation system. According to FIG. 11, the normal-pressure fuel cell power generation system 70 can use city gas supplied from each gas company as fuel gas. That is, the city gas supplied to the system is sent to the reformer 71 and reformed, and as a result, hydrogen gas is generated. The generated hydrogen gas is sent to a fuel electrode 72 a of a fuel cell main body (hereinafter, also simply referred to as a fuel cell) 72. On the other hand, air is supplied to the air electrode 72b of the fuel cell 72 through a blower or the like.
Sent to

The hydrogen gas sent to the fuel electrode 72a is converted into hydrogen ions by the catalytic action of the fuel electrode 72a.
The oxygen in the air sent to b becomes oxygen ions by the catalytic action of the air electrode 72b. The hydrogen ions pass through the electrolyte and electrochemically react with oxygen ions at the air electrode 72b,
As a result, water is generated, and electricity (direct current) is generated between the two electrodes. The generated DC electricity is orthogonally transformed by an orthogonal transformation device (not shown) having an inverter or the like, thereby generating AC electricity.

The hydrogen gas sent to the fuel electrode 72a is not completely reacted, but about 15% to 20% of the hydrogen gas supplied to the fuel electrode 72a remains unreacted. This unreacted hydrogen gas is sent to the reformer 71 and burned, so that it is used for the reforming of the reformer 71 described above.

The heat generated during power generation in the fuel cell 72 is absorbed and cooled by the cooling passed through the cooling plate 72c. The cooling water heated by the absorption cooling is sent to the steam separator 73 and separated into water and steam. The separated water is returned to the cooling plate 72c to be cooled again, and the separated water vapor is sent to a heat recovery device or the like (not shown) to recover thermal energy.

[0011]

As described above, the conventional normal-pressure fuel cell power generation system has advantages such as simplicity of the system configuration as compared with the pressurized fuel cell power generation system. However, there is a problem that the power generation efficiency is lower than that of the pressurized type. For this reason, it has been desired to make the power generation efficiency at least as high as or higher than that of the pressurized type in order to improve the practicality and economy of the normal pressure type fuel cell power generation system.

The present invention has been made in view of the above-described circumstances, and effectively utilizes unreacted hydrogen discharged from a fuel cell main body to improve power generation efficiency and fuel cell operation efficiency.
It is an object of the present invention to provide a fuel cell power generation system and a combined power generation plant capable of dramatically improving operability and the like.

[0013]

Means for Solving the Problems To achieve the above object, the present inventors have determined that the combustion temperature of the unreacted reformed gas discharged from the fuel electrode outlet of the fuel cell body is about 1250 ° C. The temperature required for reforming the reformer is about 800 to 85
0 ° C., and noticed that there was a large difference (temperature gap). In other words, conventionally, the high-temperature combustion energy of the unreacted reformed gas is used only for reforming the reformer that can be sufficiently used even at a temperature lower than that temperature. Had occurred.

Accordingly, the present inventors have developed a method of burning unreacted hydrogen gas having high-temperature combustion energy by a gas turbine generator or the like to generate electric energy, and generating an exhaust gas having a temperature range required for reforming generated by the combustion. An innovative power plant with almost no energy loss has been devised by supplying methane to the reformer.

Further, the reforming action of the reformer is not based on the conventional combustion of unreacted reformed gas, but rather by exchanging heat between exhaust gas sent from a gas turbine generator or the like and fuel gas. Because of this, the structural design of the reformer itself was facilitated, and the cost was reduced.

That is, the fuel cell power generation system according to the first aspect includes a fuel cell body having a fuel electrode and an air electrode, and a reforming means for reforming the fuel gas to generate a reformed gas. In a fuel cell power generation system that generates an electric energy by performing an electrochemical reaction between the reformed gas supplied to the fuel electrode and the air supplied to the air electrode, the fuel gas is discharged from the fuel electrode without reacting with the air. An energy generating means for burning unreacted reformed gas to generate energy, and an exhaust gas supply means for supplying exhaust gas discharged by the combustion to the reforming means, wherein the reforming means comprises the fuel A heat exchange reformer is provided for reforming the fuel gas by exchanging heat between the gas and the exhaust gas.

[0017] In the fuel cell power generation system according to claim 2, the heat exchange reformer has a reforming tube for generating a reforming action through the fuel gas, and the reforming tube is a combustion type reformer. It is made of a material with lower temperature resistance than the reforming tube of the vessel.

The combined cycle power plant according to the third aspect of the present invention includes a fuel cell body having a fuel electrode and an air electrode, and a reforming means for reforming the fuel gas to generate a reformed gas. A fuel cell power generation system for generating an electric energy by performing an electrochemical reaction between the supplied reformed gas and the air supplied to the air electrode; and an unreacted reformer discharged from the fuel electrode without reacting with the air. A gas turbine generator that burns high quality gas and generates electric energy based on the combustion gas; and an exhaust gas supply unit that supplies exhaust gas discharged by the combustion to the reforming unit.

According to a fourth aspect of the present invention, the reforming means includes a heat exchange reformer for exchanging heat between the fuel gas and the exhaust gas to reform the fuel gas.

According to a fifth aspect of the present invention, the combined power plant includes a branch supply unit that branches a part of the fuel gas supplied to the reforming unit and supplies the branched fuel gas to the gas turbine generator.

According to a sixth aspect of the present invention, the fuel cell body has a cooling plate, and supplies cooling water to the cooling plate to absorb heat generated during the electrochemical reaction. A cooling water circulation supply unit that separates the heated cooling water into steam and water, and supplies the separated water to the cooling plate again; and a steam supply unit that supplies the separated steam to the gas turbine generator. ing.

In the combined cycle power plant according to claim 7, the steam supply means exchanges heat between the exhaust gas discharged from the reformer and the separated steam used in the reforming operation of the reformer. And a heated steam supply means for supplying at least a part of the heated steam heated by the heat exchange to the gas turbine generator.

In the combined power plant according to the present invention, the gas turbine generator includes a generator, a turbine main body for generating motive energy for the generator, and a compressor for compressing external air to generate high-pressure gas. , The high-pressure gas,
The unreacted reformed gas, the branched fuel gas,
And a combustor for generating high-pressure combustion gas by burning the steam and supplying the high-pressure combustion gas to the turbine main body to drive the turbine main body, wherein the exhaust gas discharged by driving the turbine main body is provided. The compression ratio of the compressor is set to be lower than the compression ratio of a compressor included in a normal gas turbine generator, while being supplied to the reforming unit.

[0024] In the combined cycle power plant according to the ninth aspect, the fuel utilization rate representing the ratio between the fuel gas supplied to the fuel electrode and the unreacted reformed gas discharged from the fuel electrode is determined by using a normal fuel cell body. Is set lower than the fuel utilization rate.

[0025] In the combined power plant according to claim 10,
Of the exhaust gas discharged from the reformer and the high-pressure gas sent from the compressor to the combustor, the unreacted hydrogen gas sent from the fuel electrode to the combustor, and a part of the branched fuel gas Heat exchange means for exchanging heat with at least one is provided, and at least one of the high-pressure gas, the unreacted reformed gas, and the branched fuel gas heated by the heat exchange is sent to the combustor. ing.

In the combined cycle power plant according to claim 11,
A combustor is provided for burning the exhaust gas discharged by driving the turbine body, and the exhaust gas burned by the combustor is sent to the reformer.

[0027] In the combined cycle power plant according to claim 12,
An unreacted reformed gas supply line for supplying the unreacted reformed gas from the fuel electrode to the gas turbine generator is provided, and a booster compressor for increasing the pressure of the unreacted gas is provided on this line.

[0028] In the combined cycle power plant according to claim 13,
The branch supply unit includes a branch line that branches a part of the fuel gas supplied to the reforming unit and connects the branch to the gas turbine generator. A pressure compressor for increasing the pressure of the gas.

[0029] In the combined cycle power plant according to claim 14,
A heat recovery device that recovers heat energy and uses heat is provided, and the heated steam supply unit supplies a required amount of the heated steam heated by the heat exchange to the gas turbine generator, and removes the remaining heated steam. A co-supply means for supplying the heat recovery device is provided.

[0030] In the combined cycle power plant according to claim 15,
The fuel cell main body is a phosphoric acid type fuel cell main body.

According to the present invention, the unreacted reformed gas discharged from the fuel electrode is sent to an energy generator (for example, a gas turbine generator) and burned, and the combustion gas generates energy such as power generation energy. Is done. And
The exhaust gas discharged as a result of the combustion is sent to a reformer and used for a reforming action based on heat exchange with fuel gas.

Accordingly, the high-temperature combustion energy of the unreacted hydrogen gas can be utilized to the maximum,
It is possible to provide a fuel cell power generation system and a combined power generation plant having a power generation efficiency exceeding that of a conventional pressurized fuel cell power generation system or the like.

[0033]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows the configuration of a normal-pressure fuel cell power generation system according to this embodiment. According to FIG. 1, a normal-pressure fuel cell power generation system 1 includes, for example, a fuel cell power generation unit 3 having a fuel cell main body (a phosphoric acid type fuel cell main body) 2 using a phosphoric acid aqueous solution as an electrolyte, and a fuel in an unreacted state. A gas turbine generator 4 for generating electric energy based on hydrogen gas discharged from the battery body 2 is provided. The present system provides a combined power generation in which the fuel cell power generation unit 3 and the gas turbine generator 4 are combined. It is configured as a plant.

In the power generation by the fuel cell main body 2 of the present embodiment, natural gas (city gas) sent from a gas company or the like near the place where the power generation system is installed is used as the fuel gas. That is, the fuel cell power generation unit 3 includes an ejector 11 for increasing the pressure of the fuel gas (city gas) sent from the gas company via the gas supply line 10, and the ejector 11.
A reformer 12 that reforms the city gas pressurized by the gas to generate and output a reformed gas (hydrogen gas), and carbon monoxide (CO) contained in the hydrogen gas generated by the reformer 12.
And a carbon monoxide converter 13 having a concentration of 0.5% or less.

The hydrogen gas output from the carbon monoxide converter 13 is supplied to the fuel electrode 2a of the fuel cell body 2. On the other hand, air is supplied to the air electrode 2 b of the fuel cell main body 2 via the blower 14.

The fuel cell body 2 forms a stack by stacking a large number of unit cells (also referred to as cells) having a stacked structure including the above-described fuel electrode 2a, air electrode 2b, and an electrolyte layer (not shown). Are arranged in large numbers to form a large-capacity battery body.

In each unit cell of the fuel cell body 2 having a multi-stack structure, as described in the conventional example, hydrogen ions based on the hydrogen gas generated at the fuel electrode 2a and oxygen based on the air generated at the air electrode 2b are used. Electrochemical reaction with ions produces water, and direct current is generated between the two electrodes. The generated DC electricity is orthogonally transformed by an orthogonal transformation device 15 having an inverter or the like, so that AC electricity is generated and sent to each substation or the like.

In the fuel cell body 2 having such a multi-stack structure, a cooling plate 2c is provided for each of the plurality of stacks (normally, about 4 to 7 fuel cells as a whole). By passing this temperature (referred to as the cell cooling water temperature), heat generated during power generation of the fuel cell main body 2 is absorbed and cooled. The cooling water heated by the absorption cooling is sent to the steam separator 16 to be separated into water and steam, and the separated water is returned to the cooling plate 2c by the cooling water circulation pump 17.

In the above-described electrochemical reaction, a certain amount of hydrogen gas remains unreacted in order to prevent corrosion of the fuel cell body 2 and increase the stability of the fuel cell itself. In the normal fuel cell body 2, the utilization rate U of hydrogen gas (the ratio between the amount of hydrogen gas at the inlet of the fuel electrode and the amount of hydrogen gas at the outlet of the fuel electrode) is determined by the value of the normal phosphoric acid fuel cell power generation system 80 ≦ U (%) ≦ 85).

The gas turbine generator 4 of the present system is configured to generate electric energy based on hydrogen gas having a combustion temperature of about 1250 ° C. discharged from the fuel electrode outlet 18 in this unreacted state. I have.

That is, the gas turbine generator 4 generates a combustion gas for driving the turbine body 20, a compressor (compressor) 21, and a generator (G) 22 attached to one shaft. And a combustor 23 that performs the combustion.

According to the gas turbine generator 4, the compressor 21 takes in external air through the air supply line 24 and compresses it. At this time, the compression ratio C of the compressor 21 is set to a value (3 atg ≤ C ≤ 10 atg) lower than the normal compression ratio Cn of the gas turbine generator (10 atg <Cn ≤ 30 atg). The compressed gas is sent to the combustor 23.

On the other hand, the unreacted hydrogen gas discharged from the fuel electrode outlet 18 is guided through a discharged hydrogen gas line 25, is pressurized by a pressurizing compressor 26 on the way, and is sent to the combustor 23 of the gas turbine generator 4. Can be Combustor 23
Burns the unreacted hydrogen gas, the compressed gas, and the like to generate a high-pressure combustion gas, and sends the high-pressure combustion gas to the turbine body 20.

The turbine body 20 is driven based on the sent high-pressure combustion gas to generate power, and the power drives the generator 22 to generate power.

Since the compression ratio C of the compressor 21 is lower than the normal compression ratio Cn as described above, the combustion gas generated by driving the turbine body 20 is approximately 80%.
It has a temperature of 0 to 850 ° C., which is a temperature required for reforming the reformer 12. This combustion gas (exhaust gas)
Is sent to the reformer 12 via the exhaust gas line 28.

The reformer 12 has a plurality of reforming tubes 30 each having a predetermined length and having a reforming catalyst therein. By passing the city gas sent from the ejector 11 through the reforming tubes 30,
It is configured to reform by catalytic action.

The reformer 12 of the present embodiment raises the temperature of the city gas in the reforming pipe 30 necessary for generating the above-described reforming action by burning unreacted hydrogen gas as in the related art. Instead of the gas turbine generator 4 to the reformer 12
This is performed by exchanging heat between the exhaust gas supplied to the inside and the city gas flowing through the reforming pipe 30.

The exhaust gas used for reforming in the reformer 12 is sent to the heat exchanger 31. On the other hand, the heat exchanger 31
The steam separated by the steam separator 16 is sent through the steam supply line 32, and heat exchange is performed between the steam and the exhaust gas.

As shown in FIG. 1, high-temperature steam from which heat energy has been recovered from exhaust gas by heat exchange is supplied to a combustor 2 of a gas turbine generator 4 through a steam supply line 33.
3 to the combustor 23 of the gas turbine generator 4
It is used as combustion assist energy in

In this configuration, as shown in FIG. 1, a branch line 35 is provided which branches off from the gas supply line 10 and connects the gas supply line 10 to the combustor 23 of the gas turbine generator 4. A boost compressor 36 is installed on the branch line 35 so that a part of the supplied fuel (city gas) is sent to the combustor 23 of the gas turbine generator 4.

That is, a part of the city gas supplied through the gas supply line 10 branches through the branch line 35, is boosted in pressure through the booster compressor 36, and is combusted by the combustor of the gas turbine generator 4. The gas is supplied to the gas turbine generator 23 and is used as auxiliary combustion energy in the combustor 23 of the gas turbine generator 4.

Next, the operation of the normal pressure type fuel cell power generation system of this configuration will be described.

According to the present configuration, a predetermined amount of the city gas supplied through the gas supply line 10 is sent to the reformer 12 and reformed, and the hydrogen gas is supplied through the carbon monoxide converter 13 to the reformer 12. Is sent to the fuel electrode 2a of the fuel cell body 2. The remaining city gas is sent to the gas turbine generator 4 via the branch line 35 and the boost compressor 36.

In the fuel cell main body 2, direct current electricity is generated by an electrochemical reaction between the hydrogen gas sent to the fuel electrode 2 a and the air sent to the air electrode 2 b via the blower 14. Output as AC electricity.

At this time, the unreacted hydrogen discharged from the fuel electrode 2a of the fuel cell body 2 has a high-temperature heat energy of about 1250 ° C. by combustion, and therefore, the high-temperature region of this heat energy is mainly The gas turbine generator 4 is driven to generate electric power, and the remaining temperature range (about 800 ° C.
850 ° C.) is used for reforming of the reformer 12.

That is, in the gas turbine generator 4, unreacted hydrogen gas sent from the fuel electrode outlet 18, compressed gas sent from the compressor 21, city gas sent through the branch line 35 as auxiliary fuel energy, and High-quality steam sent from the steam separator 16 through the heat exchanger 31 and the steam supply lines 32 and 33 is burned by the combustor 23 as auxiliary energy to generate power energy for driving the turbine body 20. The turbine main body 20 is driven based on the power energy, and power is generated by the generator (G).

Then, the combustion gas generated by driving the turbine body 20 is discharged to the reformer 12 through the exhaust gas line 28. At this time, the exhaust gas is supplied to the reformer 1
Since it has thermal energy at a temperature of about 800 to 850 ° C. sufficient for the reforming operation of No. 2, heat is exchanged with the city gas sent to the reformer 12. As a result, the city gas is reformed.

The exhaust gas used for the reforming is supplied to the heat exchanger 3
The heat is exchanged with the above-described steam through the heat exchanger 1, and the heat energy is recovered and exhausted.

Here, when the total amount (energy) of city gas is assumed to be 100%, the fuel cell power generation system 1 of this configuration
FIG. 2 shows the energy balance.

According to FIG. 2, 65% of the city gas (100%) is the fuel cell power generation unit 3 (abbreviated as FC in FIG. 2).
, And 35% of the turbine generator 4 (T /
G). This city gas (65
%), The DC terminal (DC terminal) of the fuel cell power generation unit 3
In this case, 28.9% of electric energy can be obtained.
0%, and 27.9% of electric energy can be obtained at the power transmission terminal output (transmission terminal AC) of the fuel cell power generation unit 3. In addition, INV
The loss is a loss in the inverter (INV) of the orthogonal transform device 15, and the auxiliary equipment loss is a loss in an auxiliary equipment part (not shown).

On the other hand, from the fuel electrode outlet 18, 18.9% of the energy (100%) of the city gas is output as unreacted hydrogen gas (fuel electrode off gas), and this unreacted hydrogen gas is supplied to the gas turbine generator 4. ((1) in the figure)
Further, 32.3% of the total steam is sent from the steam separator 16 to the gas turbine generator 4 (see (2) in the figure).

In the gas turbine generator 4, the above-mentioned 35% city gas, 18.9% fuel electrode off-gas,
And 32.3% water vapor, 20.4% electrical energy at the turbine generator power generation end (T / G start end), and 19.19 at the turbine generator power transmission end (T / G transmission end). 0% electrical energy is obtained. The air C
The omp power is power energy of the compressor 21 of the gas turbine generator 4.

The 15.5% gas turbine generator 4
(T / G exhaust gas) is sent to the reformer 12 of the fuel cell power generation unit 3 (see (3) in the figure).

As shown in FIG. 2, the energy of the unreacted hydrogen gas (fuel electrode off-gas) discharged from the fuel electrode outlet 18 and the energy of the water vapor sent from the vapor separator 16 are utilized to the maximum extent to achieve gas It can be seen that the power generation efficiency of the fuel cell power generation unit 3 is improved by increasing the power generation efficiency of the turbine generator 4 and maximizing the energy of the exhaust gas sent from the gas turbine generator 4.

That is, in this embodiment, the combustion temperature of the unreacted hydrogen discharged from the fuel electrode 2a is about 1250.
Since the high-temperature heat energy of ° C. is used very efficiently for power generation, reforming, and heat exchange, the overall power generation efficiency can be dramatically improved.

FIG. 3 shows the battery cooling water temperature and the combustor 23 set in the fuel cell power generation system 1 of this configuration.
In addition to showing the values of the parameters such as the temperature of the exhaust gas at the outlet, the efficiency of the power generation end and the efficiency of the power transmission end obtained by the system having the parameter values are also shown. A in FIG. 3 corresponds to FIG.
In the fuel cell power generation system B based on the configuration of FIG. 1, in the configuration of FIG. 1, the number of cooling plates 2c in the fuel cell main body 2 is increased to increase the battery cooling water temperature (the cell temperature is not changed), and the steam separator 16 shows a system in which the generated steam pressure is increased, and C shows a system in which each parameter value is maximized in the configuration of FIG. In FIG. 3, S / C is a molar ratio of steam to carbon in the ejector 11.

According to FIG. 3, in the system A, the transmitting end efficiency is about 46.7% and the generating end efficiency is about 48.4%.
It can be seen that in the system B, the transmitting end efficiency is about 47.4% and the generating end efficiency is about 49.3%. In the system C, the transmitting end efficiency is about 47.8% and the generating end efficiency is about 4%.
It can be seen that 9.5% is obtained.

Subsequently, the power generation efficiencies obtained by the fuel cell power generation system A and the fuel cell power generation system B shown in FIG. 3 are compared with the conventional pressurized fuel cell power generation system and the conventional normal pressure fuel cell power generation system. FIG. 4 shows the result of the comparison. The conventional pressurized fuel cell power generation system and the conventional normal pressure fuel cell power generation system include (1) a cogeneration system (a type in which steam generated by a steam separator is used for producing cold water) and (2) a high efficiency system. (A type in which power is recovered by a steam turbine from steam generated by a steam separator), and (2) requires cooling the steam at the turbine outlet, and requires a large amount of cooling water.

According to FIG. 4, the power generation efficiency of the fuel cell power generation system (normal pressure combined cycle power plant) of the present configuration is significantly improved as compared with the power generation efficiency of the conventional cogeneration system. It can be seen that the power generation efficiency of the high-efficiency system, which has been recovered to achieve high power generation efficiency, is greatly improved.

As described in detail above, according to the normal pressure type fuel cell power generation system of the present embodiment, the conventional pressure type fuel cell power generation system or 48-49% greatly exceeds the conventional normal pressure type fuel cell power generation system. Power generation efficiency can be obtained. This power generation efficiency is comparable to the latest high-efficiency thermal power generation (power generation efficiency of about 49%), and can significantly improve the performance and practicality of the normal pressure fuel cell power generation system.

In particular, since the normal pressure type fuel cell power generation system of this configuration is applied to a normal pressure type phosphoric acid type fuel cell whose reliability, power generation performance and the like are being verified at present, it is extremely feasible. Has become.

Further, according to the fuel cell power generation system of this configuration, the gas turbine generator is used, and the cost per kW of the gas turbine generator (about 200,000 to 300,000 yen /
kW) and installation space (about 0.05 m ² / kW) are lower than the cost per kW and installation space of the fuel cell. Therefore, this system incorporating a gas turbine generator is a phosphoric acid fuel cell power generation system alone (target cost: about 100,000 yen / kW, installation space:
(Approximately 0.07 to 0.15 m ² / kW).

Further, according to the fuel cell power generation system of this configuration, the operating characteristics are improved as compared with the conventional normal pressure type phosphoric acid fuel cell power generation system for the following reasons. That is, in the conventional normal pressure phosphoric acid fuel cell power generation system, the fuel gas (natural gas, city gas, etc.) is boosted / conveyed by the ejector. However, since there is not enough room for the boosting power, the fuel cell body ( In order to achieve an appropriate flow distribution in the stack), the pressure distribution design in the fuel processing system has been troublesome.

For example, in the conventional normal-pressure phosphoric acid fuel cell power generation system, the output pressure of the ejector is "0.0
x atmospheric pressure ", and the pressure of the exhaust gas is the atmospheric pressure, so that the pressure loss generated through system components such as the fuel cell body and the heat exchanger during this time must be within the differential pressure between the atmospheric pressure and the output pressure. Since it was not operated as a system, great care had to be paid to the management of ejectors.

However, according to the fuel cell power generation system of this configuration, since the booster compressor is installed on the exhaust hydrogen gas line or branch line connecting the fuel electrode outlet and the combustor of the gas turbine generator, the booster of the ejector is increased. Even if the capacity is slightly reduced, it will be compensated by the suction force of the boost compressor, so that the operability can be remarkably improved.

According to the fuel cell power generation system of this configuration, the operation stability is improved as compared with the conventional phosphoric acid type fuel cell power generation system for the following reasons.

That is, according to the conventional phosphoric acid type fuel cell power generation system, the unreacted hydrogen gas discharged from the fuel cell body is reduced to the minimum amount necessary for combustion in the reformer in order to improve power generation efficiency. Is suppressed. That is, in the conventional phosphoric acid fuel cell power generation system, the fuel utilization rate U is expressed as “80 ≦
U (%) ≦ 85 ”is set, and the hydrogen gas near the fuel cell main body outlet is operated in a very lean state. However, if power generation efficiency can be maintained,
It is desired to improve the stability of the fuel cell body by decreasing the fuel utilization rate U (for example, “U = about 70%”) to increase the concentration of hydrogen gas.

In this regard, according to the fuel cell power generation system of this configuration, even if the fuel utilization rate U is reduced (for example, “U = about 70%”), the fuel is transmitted to the gas turbine generator via the branch line. By increasing the amount of fuel gas supplied to the fuel cell body by reducing the fuel gas by the amount corresponding to the reduction rate, it is possible to operate the fuel cell body stably while maintaining overall power generation efficiency become.

Further, according to this configuration, since a part of the steam and the fuel can be supplied to the turbine generator, the calorific value of the exhaust gas sent to the reformer can be increased.
Therefore, even when the calorie of the exhaust gas sent from the turbine generator to the reformer is less than the calorie required for the heat exchange action in the reformer, the calorie of the exhaust gas increases with the combustion of steam and fuel gas. Therefore, a favorable modifying action can be maintained. In addition, supply of steam and fuel to a part of the turbine generator is performed, for example, if electric energy is efficiently generated based on unreacted hydrogen gas, and exhaust gas having a necessary calorific value is sent to the reformer, It can be omitted.

Further, according to the fuel cell power generation system of this configuration, since the upper limit of the turbine inlet temperature is restricted by the heat resistance of the turbine blade, the compression ratio C is set to (3 atg ≦ C ≦
10 atg), and the temperature of the gas turbine outlet gas supplied to the reformer is set to about 800 to 850 ° C required for reforming. That is, the compression ratio of the compressor of the gas turbine generator is set to the normal compression ratio Cn (10 atg <Cn ≦ 3).
0 atg). Generally, in a gas turbine, it is indispensable to raise the turbine inlet temperature as much as possible and lower the turbine outlet temperature as much as possible to improve the efficiency. Therefore, the higher the efficiency of the gas turbine, the higher the compression ratio. Has a compressor. In order to design and manufacture a gas turbine generator provided with a compressor having such a high compression ratio, advanced design technology and manufacturing technology are required, and the cost has been increased accordingly.

However, according to the gas turbine generator of this configuration, the above-described high-efficiency gas turbine generator and the like are not required, and the compression ratio C (3 atg ≦ C) is lower than the normal compression ratio.
≦ 10 atg) A gas turbine generator having a compressor set to ≦ 10 atg) may be designed and manufactured. Therefore, the design and production of the compressor itself and the gas turbine generator are facilitated, and the design and production costs are reduced.

According to the fuel cell power generation system of the present configuration, since the steam separated by the steam separator is used as auxiliary fuel for the gas turbine generator, a conventional cogeneration system is used. And the cost and installation space of the entire system can be reduced. In addition, when the cogeneration is not performed, the fuel cell power generation system does not need to be installed in the vicinity of the heat demand point, so that the selection range of the system introduction point can be expanded.

On the other hand, according to this configuration, a heat exchange type reformer for exchanging heat between the exhaust gas discharged from the turbine generator and the fuel gas (city gas) to reform the fuel gas is used. It has the following advantages as compared with the case where a conventional combustion reformer is used.

That is, in the heat exchange type reformer of this configuration,
Since it is not necessary to provide a combustion section, a combustion space, and the like, which are required in the conventional combustion type reformer, the size can be made very compact as compared with the conventional combustion type reformer.

In particular, in the reformer of this configuration, the reforming is performed by the heat transfer action of the sent exhaust gas. Such a heat transfer action is required if the entire reformer is compact. The higher the efficiency, the more compact and improved the heat transfer performance can be realized.

Further, in the conventional combustion type reformer, since the reforming is performed using the combustion gas obtained by burning the unreacted hydrogen gas, the combustion gas becomes extremely high temperature (for example, about 1300 ° C.). Therefore, in the conventional combustion-type reformer, a high-temperature-resistant high-quality material pipe must be used as the reforming pipe.

However, in the heat exchange reformer of this configuration, the reforming is performed by the heat exchange between the exhaust gas at a certain temperature (for example, about 850 ° C.) required for the reforming and the city gas (and the catalyst). Therefore, it is not necessary to use a high-quality pipe having high temperature resistance, which is very excellent in cost. In addition, since high-temperature combustion gas is not used, durability is improved as compared with the related art.

Further, in the conventional combustion type reformer, the reforming action is generated by radiant heat transfer based on the combustion gas. However, in such radiant heat transfer by the combustion gas, the temperature of each reforming pipe is reduced. There is a possibility that the fuel conversion rate becomes non-uniform and the fuel conversion rate (methane conversion rate) deteriorates. However, according to the heat exchange type reformer of this configuration, since the reforming is performed by the heat transfer of the exhaust gas, the temperature of each reforming tube can be uniformly increased. Therefore, the fuel conversion rate (methane conversion rate)
Can be easily set higher.

In the conventional combustion reformer, as described above, the temperature distribution in the reforming pipe based on the combustion gas becomes very uneven, so that part of the combustion gas becomes extremely high. Therefore, to prevent the gas and catalyst inside the reforming tube from being damaged by direct contact of the reforming tube with such high-temperature combustion gas,
A heat insulating cap (ceramic cap) is provided at a portion of the reforming tube where the high-temperature combustion gas comes into contact. However, in the heat exchange type reformer of this configuration, since the reforming is performed by the heat exchange action, such a very high-temperature combustion gas is not generated, and the heat insulating cap described above is not required. Thus, the cost of parts can be reduced.

In this embodiment, high-temperature steam obtained by recovering heat energy from exhaust gas by heat exchange by the heat exchange device 31 is used as auxiliary combustion energy of the gas turbine generator 4. Instead of supplying all the separated steam to the gas turbine generator 4, a part of the steam can be used for cogeneration. That is, as shown in FIG. 5, according to this normal pressure fuel cell power generation system 40, the heat exchanger 31
A valve 41 is provided on a steam supply line 32 connecting the gas turbine generator 4 and the combustor 23 of the gas turbine generator 4.
The steam separated in 6 may be configured to be supplied to the combustor 23 through the valve 41 and to the heat recovery unit 42 through the valve 41. With this configuration, the sent steam is recovered as heat energy by the heat recovery device 42 and used for various heat utilization devices such as hot water for heating.

That is, according to this configuration, the steam separator 1
The high-quality steam separated in Step 6 can be used also for heat and heat supply, and a function for both power generation and heat and heat supply can be realized without changing the system configuration (only by adding the valve 41). Further, by controlling the throttle of the valve 41, the amount of water vapor sent to the heat recovery device 42 can be continuously changed.

Next, a modification of the fuel cell power generation system shown in FIG. 1 is shown in FIG. This fuel cell power generation system 5
According to FIG. 0, as shown in FIG.
A heat exchanger 51 for exchanging heat between the compressed gas sent to the combustor 23 by the compressor 21 and the exhaust gas sent from the reformer 12 to the heat exchanger 31 is provided. Note that the other configuration is substantially the same as the configuration in FIG. 1, and a description thereof will be omitted.

According to this structure, the compressed gas sent to the combustor 23 is heated through the heat exchanger 51, so that the high-pressure combustion generated in the combustor 23 by the heat energy of the heated compressed gas. The energy of the gas increases. Therefore, the power energy of the turbine body 20 increases, and the power generation efficiency of the gas turbine generator 4 and the entire system can be improved.

Further, modified examples of the fuel cell power generation system shown in FIG. 1 are shown in FIGS. According to the fuel cell power generation system 53 shown in FIG. 7, the city gas sent to the combustor 23 of the gas turbine generator 4 via the branch line 35 and the emission sent to the heat exchanger 31 from the reformer 12. A heat exchanger 54 for exchanging heat with gas is provided. As a similar modification, the fuel cell power generation system 5 shown in FIG.
According to 5, the unreacted hydrogen gas discharged from the fuel electrode outlet 18 and sent to the combustor 23 of the gas turbine generator 4 via the discharged hydrogen gas line 25 and the reformer 12 to the heat exchanger 31 Heat exchanger 5 for exchanging heat with sent exhaust gas
6 are provided. Note that the other configuration is substantially the same as the configuration in FIG. 1, and a description thereof will be omitted.

With this configuration, the city gas or the unreacted hydrogen gas sent to the combustor 23 is heated via the heat exchanger 54 or 56, so that the heated city gas or the unreacted hydrogen gas is heated. Combustor 2 by thermal energy
The energy of the high-pressure combustion gas generated in 3 increases.
Therefore, the power energy of the turbine body 20 increases, and the power generation efficiency of the gas turbine generator 4 and the entire system can be improved.

FIG. 9 shows a modification of the fuel cell power generation system shown in FIG. According to the fuel cell power generation system 60 shown in FIG. 9, the exhaust gas is discharged from the turbine
A combustor 61 is provided for burning the exhaust gas guided through 8 and sending it to the reformer 12. The combustion energy of the combustor 61 may be such that reformed gas (hydrogen gas) reformed by the reformer 12 is supplied through a reformed gas supply line 62 as shown in FIG. Fuel gas (city gas) may be supplied. Note that the other configuration is substantially the same as the configuration in FIG. 1, and a description thereof will be omitted.

The configuration shown in FIG. 9 is used, for example, when the temperature of the exhaust gas discharged from the turbine body 20 does not satisfy the temperature (about 800 ° C. to 850 ° C.) required for the reforming operation of the reformer 12. Applied. That is, according to this configuration,
Even if the temperature of the exhaust gas discharged from the turbine main body 20 is lower than the above-mentioned about 800 ° C to 850 ° C, the exhaust gas is once burned through the combustor 61 and the above-mentioned about 800 ° C to 850 ° C. Alternatively, since the temperature is raised to a temperature exceeding the range and then sent to the reformer 12, a good reforming action can be obtained.

It is to be noted that each of the configurations shown in FIGS. 5 to 9 can be realized by combining them with each other.

Further, according to this embodiment, the steam separated by the steam separator is heat-exchanged with the exhaust gas of the reformer and then supplied to the gas turbine generator. However, the present invention is not limited to this. Instead, steam can be supplied directly to the gas turbine generator.

Further, in the fuel cell power generation system of the present configuration, instead of a power plant such as a gas turbine generator, another energy generating device such as thermal energy can be used by using the unreacted hydrogen gas.

That is, the normal-pressure fuel cell power generation system 65 shown in FIG.
An energy generator 66 is provided. Note that the other configuration is substantially the same as the configuration in FIG. 1, and a description thereof will be omitted.

The energy generator 66 burns the unreacted hydrogen gas, the steam supplied through the steam supply line 33, the city gas sent through the branch line, and the like to generate, for example, motive energy. Then, energy such as electric energy is generated from the power energy. Then, the exhaust gas (800
C. to 850 ° C.) to the reformer 12. With this configuration, the power generation efficiency of the entire system is reduced because only the fuel cell body is used. However, on the other hand, other energy is generated and the energy can be used effectively. In addition, since a heat exchange reformer can be used, the various advantages described above by using a heat exchange reformer can be enjoyed.

In this embodiment, the reformer is a heat exchange reformer, but it is of course possible to use a conventional combustion reformer.

Further, in this embodiment, the case where the present invention is applied to the normal pressure type phosphoric acid fuel cell power generation system has been described. However, the present invention is not limited to this. The present invention is also applicable to various fuel cell power generation systems, such as a fuel cell power generation system of a fuel cell type and a normal pressure type solid electrolyte fuel cell power generation system.

[0106]

As described above, according to the fuel cell power generation system and the combined power generation plant of the present invention, the high-temperature combustion energy of the unreacted reformed gas discharged from the fuel cell body is converted into the electric energy and the reforming action. The power generation efficiency can be greatly increased over the conventional pressurized fuel cell power generation system and the conventional normal pressure fuel cell power generation system. As a result, the performance and practicality of the fuel cell power generation system can be dramatically improved.

Further, since the fuel cell power generation system and the combined power generation plant of the present invention can be applied to a normal pressure phosphoric acid type fuel cell, the feasibility is very high.

Furthermore, according to the combined cycle power plant using the gas turbine generator of the present invention, the cost and the installation space can be reduced as compared with, for example, the phosphoric acid type fuel cell power generation system alone, so that it is very practical. High plant.

In particular, according to the combined cycle power plant of the present invention, the booster compressor can be provided on the unreacted reformed gas supply line or on the branch line. And the operability of the system is improved.

Further, according to the combined cycle power plant of the present invention, even if the fuel utilization rate of the fuel cell main body is made lower than the normal fuel cell main body utilization rate, the amount of fuel gas branching corresponding to the decrease is reduced. , The system can be operated stably while maintaining the power generation efficiency.

On the other hand, according to the fuel cell power generation system and the combined power generation plant of the present invention, the heat exchange between the exhaust gas discharged from the turbine generator (energy generating device) and the fuel gas to reform the fuel gas is performed. Since an exchange-type reformer can be used, it can be designed very compact as compared with a conventional combustion-type reformer. In addition, since the temperature resistance design is eased, the design becomes easy, so that the manufacturing cost can be reduced and the durability can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a normal-pressure fuel cell power generation system according to an embodiment of the present invention.

FIG. 2 is a diagram showing an energy balance of the normal pressure fuel cell power generation system according to the embodiment.

FIG. 3 is a diagram showing parameter values in the normal-pressure fuel cell power generation system of the present embodiment and power generation efficiency values of the system obtained based on the parameter values.

FIG. 4 shows the results of comparing the power generation efficiencies obtained by the fuel cell power generation system A and the fuel cell power generation system B shown in FIG. 3 with those of the conventional pressurized fuel cell power generation system and the conventional normal pressure fuel cell power generation system. FIG.

FIG. 5 is a block diagram showing a modified example of the normal-pressure fuel cell power generation system of the embodiment.

FIG. 6 is a block diagram showing a schematic configuration of a modified example of the normal-pressure fuel cell power generation system of the present embodiment.

FIG. 7 is a block diagram showing a schematic configuration of a modified example of the normal pressure fuel cell power generation system of the present embodiment.

FIG. 8 is a block diagram showing a schematic configuration of a modified example of the normal-pressure fuel cell power generation system of the present embodiment.

FIG. 9 is a block diagram showing a schematic configuration of a modified example of the normal pressure fuel cell power generation system of the present embodiment.

FIG. 10 is a block diagram showing a schematic configuration of a modified example of the normal-pressure fuel cell power generation system of the present embodiment.

FIG. 11 is a block diagram showing a schematic configuration of a conventional normal pressure fuel cell power generation system.

[Explanation of symbols]

1, 40, 50, 53, 55, 65 Atmospheric pressure fuel cell power generation system 2 Fuel cell body 2a Fuel electrode 2b Air electrode 2c Cooling plate 3 Fuel cell power generation unit 4 Gas turbine generator 10 Gas supply line 11 Ejector 12 Reformer 13 Carbon Monoxide Transformer 14 Blower 16 Steam Separator 17 Cooling Water Circulation Pump 18 Fuel Electrode Outlet 20 Turbine Body 21 Compressor 22 Generator 23, 61 Combustor 24 Air Supply Line 25 Exhaust Gas Supply Line 26, 36 Boost Compressor 28 Exhaust Gas Line 30 Reforming pipe 31, 51, 54, 52, 56 Heat exchanger 32, 33 Hydrogen vapor supply line 35 Branch line 41 Valve 42 Heat recovery device 62 Reformed gas supply line 66 Energy generation device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01M 8/00 H01M 8/06 G 8/06 B63H 21/26 E

Claims (15)

[Claims] A fuel cell body having a fuel electrode and an air electrode; and a reforming means for reforming a fuel gas to generate a reformed gas. In a fuel cell power generation system that generates an electric energy by electrochemically reacting air supplied to an air electrode, an unreacted reformed gas discharged from the fuel electrode without reacting with the air is burned to generate energy. Energy generating means for generating, and exhaust gas supply means for supplying exhaust gas discharged by the combustion to the reforming means, wherein the reforming means exchanges heat between the fuel gas and the exhaust gas. A fuel cell power generation system comprising a heat exchange reformer for reforming the fuel gas. 2. The heat exchange type reformer has a reforming tube for generating a reforming action through the fuel gas, and the reforming tube has a higher temperature resistance than a reforming tube of a combustion type reformer. 2. The fuel cell power generation system according to claim 1, wherein the fuel cell power generation system is formed of a material having a low property. 3. A fuel cell body having a fuel electrode and an air electrode, and a reforming means for reforming a fuel gas to generate a reformed gas, wherein the reformed gas supplied to the fuel electrode and the air electrode are provided. A fuel cell power generation system that generates an electric energy by causing an electrochemical reaction with air supplied to the fuel cell, and burns the unreacted reformed gas discharged from the fuel electrode without reacting with the air, and converts the combustion gas into A combined cycle power plant comprising: a gas turbine generator that generates electric energy based on the gas; and an exhaust gas supply unit that supplies exhaust gas discharged by the combustion to the reforming unit. 4. The combined cycle power plant according to claim 3, wherein said reforming means includes a heat exchange reformer for exchanging heat between said fuel gas and said exhaust gas to reform said fuel gas. 5. The combined cycle power plant according to claim 4, further comprising a branch supply unit that branches a part of the fuel gas supplied to the reforming unit and supplies the fuel gas to the gas turbine generator. 6. The fuel cell body has a cooling plate, and supplies cooling water to the cooling plate to absorb heat generated during the electrochemical reaction, and converts the cooling water heated by the heat absorption into steam. 6. The combined power generation system according to claim 5, further comprising: a cooling water circulating supply unit that separates the separated water into water and supplies the separated water to the cooling plate again; and a steam supply unit that supplies the separated steam to the gas turbine generator. plant. 7. A heat exchange means for performing heat exchange between exhaust gas discharged from the reformer and the separated steam used for the reforming operation of the reformer, and a heat exchange means. The combined steam power plant according to claim 6, further comprising: heated steam supply means for supplying at least a part of the heated steam heated by the gas turbine generator to the gas turbine generator. 8. The gas turbine generator comprises: a generator;
A turbine body that generates motive energy for the generator, a compressor that compresses outside air to generate a high-pressure gas, the high-pressure gas, the unreacted reformed gas, the branched partial fuel gas, and the A combustor for generating high-pressure combustion gas by burning steam, supplying the high-pressure combustion gas to the turbine main body, and driving the turbine main body, wherein the exhaust gas discharged by driving the turbine main body is subjected to the reforming. The combined cycle power plant according to claim 7, wherein a compression ratio of the compressor is set to be lower than a compression ratio of a compressor included in a normal gas turbine generator, while being configured to supply to the quality means. 9. A fuel utilization ratio representing a ratio between a fuel gas supplied to the fuel electrode and an unreacted reformed gas discharged from the fuel electrode is set lower than a normal fuel utilization ratio of a fuel cell body. The combined cycle power plant according to claim 8. 10. An exhaust gas discharged from the reformer, a high-pressure gas sent from the compressor to the combustor, an unreacted hydrogen gas sent from the fuel electrode to the combustor, and a part of the branched part. Heat exchange means for exchanging heat with at least one of the fuel gas is provided, and at least one of the high-pressure gas, the unreacted reformed gas, and a part of the branched fuel gas heated by the heat exchange is burned. The combined cycle power plant according to any one of claims 7 to 9, wherein the combined power plant is sent to a vessel. 11. The fuel cell system according to claim 7, further comprising a combustor for combusting exhaust gas discharged by driving the turbine body, wherein the exhaust gas combusted by the combustor is sent to the reformer. The combined cycle power plant according to any one of the preceding claims. 12. An unreacted reformed gas supply line for supplying the unreacted reformed gas from the fuel electrode to the gas turbine generator, and a booster compressor for increasing the pressure of the unreacted reformed gas is provided on the line. The combined cycle power plant according to any one of claims 3 to 11 provided. 13. The branch supply unit includes: a branch line that branches a part of the fuel gas supplied to the reforming unit and connects to the gas turbine generator; and a branch line provided on the branch line. The combined cycle power plant according to any one of claims 3 to 12, further comprising a booster compressor that boosts a part of the fuel gas. 14. A heat recovery device for recovering heat energy and utilizing the heat, wherein the heating steam supply means supplies a required amount of the heating steam heated by the heat exchange to the gas turbine generator, The combined cycle power plant according to claim 7, further comprising a co-supplying unit that supplies remaining heated steam to the heat recovery device. 15. The combined cycle power plant according to claim 3, wherein the fuel cell main body is a phosphoric acid type fuel cell main body.