JP2001283882A - Generating device utilizing fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a generating device utilizing a fuel cell which can improve the total generating efficiency even when the specific power is small. SOLUTION: The generating device utilizing a fuel cell is equipped with a fuel cell generating portion 1, a burning portion 2 which burns the exhaust gas discharged from the fuel cell generating portion 1 by oxygen containing gas, a generating turbine 4 which drives a generator 3, a compressor turbine 6 which drives a compressor 5 that compresses the oxygen containing gas to be supplied to the fuel cell generating portion, and it is so constructed that the generating turbine 4 and the compressor turbine 6 are driven by the burnt exhaust gas discharged from the burning portion 2. The generating turbine 4 and the compressor turbine 6 are connected in parallel with the burning portion 2, and a burnt exhaust gas distribution ratio control means V4 is provided which controls the distribution ratio of the burnt exhaust gas supplied to the generating turbine 4 and the compressor turbine 6.

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 section for generating electricity by supplying a fuel gas and an oxygen-containing gas, and an exhaust fuel gas discharged from the fuel cell power generation section being discharged from the fuel cell power generation section. A combustion unit for burning the exhausted oxygen-containing gas, a generator turbine for driving the generator, and a compressor turbine for driving a compressor for pressurizing the oxygen-containing gas supplied to the fuel cell power generation unit. The present invention also relates to a fuel cell-based power generator configured to drive the generator turbine and the compressor turbine with combustion exhaust gas discharged from the combustion section.

[0002]

2. Description of the Related Art As shown in FIG. 4, such a power generation device using a fuel cell (hereinafter sometimes simply referred to as a power generation device) includes a fuel cell power generation section 1 in which fuel gas and oxygen-containing gas (for example, air) are supplied. Is supplied to the fuel cell power generation unit 1, and the combustion unit 2 generates a combustion exhaust gas generated by burning the exhaust fuel gas and the exhaust oxygen-containing gas discharged from the fuel cell power generation unit 1. Then, the generator turbine 4 and the compressor turbine 6 are driven to generate electric power by the generator 3 driven by the generator turbine 4 and the compressor driven by the compressor turbine 6. At 5, the fuel cell power generation unit 1
Pressurizes the oxygen-containing gas to be supplied to the fuel cell. Since the DC power is generated in the fuel cell power generation unit 1, an inverter 7 that converts the DC power generated by the fuel cell power generation unit 1 into AC power is provided, and the AC power from the inverter 7 and the generator 3 are output. The AC power generated in step (1) is merged with the power transmission line 11 and supplied to a power demand destination.

Conventionally, as shown in FIG. 4, a turbine 6 for a compressor and a turbine 4 for a generator are provided in a state of being connected in series to a combustion section 2 so that combustion exhaust gas discharged from a burner 2 is discharged. First, the compressor turbine 6 is supplied to drive the compressor turbine 6, and the combustion exhaust gas discharged from the compressor turbine 6 is supplied to the generator turbine 4 to drive the generator turbine 4. I was trying to make it.
In adjusting the specific output, which is the ratio of the actual output to the total rated output obtained by combining the rated outputs of the fuel cell power generator 1 and the generator 3, the generator 3 is operated at a rated output or substantially constant near the rated output. The output of the fuel cell power generation unit 1 was adjusted while operating in the high output state.

In FIG. 4, reference numeral 13 denotes a fuel gas supply path for supplying fuel gas to the fuel cell power generation unit 1, and V1 denotes a fuel gas supply amount control valve for adjusting the fuel gas supply amount to the fuel cell power generation unit 1. The output of the fuel cell power generation unit 1 is adjusted by adjusting the amount of fuel gas supplied to the fuel cell power generation unit 1 by the fuel gas supply amount adjustment valve V1. When the control unit 8 is provided to perform automatic control, the power transmission path 1
1 is provided with a power meter Wm, and the control unit 8 controls the fuel gas supply amount adjusting valve V1 based on the detected power of the power meter Wm.
Was configured to be controlled.

[0005] In FIG. 4, reference numeral 18 denotes a flue gas supply passage 18 for guiding flue gas discharged from the combustion section 2.
The combustion exhaust gas supply path 18 is connected to the turbine 6 for the compressor, and the turbine exhaust gas path 31 for relay that guides the combustion exhaust gas (hereinafter, may be referred to as turbine exhaust gas) discharged from the turbine 6 after the turbine is driven. Is connected to the generator turbine 4, whereby the compressor turbine 6 and the generator turbine 4 are connected in series to the combustion unit 2.

In FIG. 4, reference numeral 14 denotes an air supply path for supplying air pressurized by the compressor 5 to the fuel cell power generation unit 1;
Reference numeral 5 denotes an exhaust gas exhaust passage for guiding exhaust fuel gas exhausted from the fuel cell power generation unit 1, and reference numeral 16 denotes an exhaust air passage for guiding exhaust air (exhaust oxygen-containing gas) exhausted from the fuel cell power generation unit 1. . Further, when the output of the fuel cell power generation unit 1 is reduced and the amount of exhaust fuel gas is reduced, the combustion exhaust gas for driving the generator turbine 4 and the compressor turbine 6 becomes insufficient. A gas fuel supply path for supplying gas fuel to the combustion unit 2 to increase the amount of exhaust gas, and V2 is a gas fuel supply amount control valve for adjusting the supply amount of gas fuel.
21 indicates that when the amount of compressed air discharged from the compressor 5 is larger than the amount corresponding to the power generation output of the fuel cell power generation unit 1,
An air bypass path branched from the air supply path 14 to supply the surplus to the combustion section 2 bypassing the fuel cell power generation section 1, and V 3 is air for adjusting the amount of air bypass by the air bypass path 21. This is a bypass amount control valve. 2
Reference numeral 2 denotes an air preheating heat exchanger for heating air flowing through the air supply path 14 with turbine exhaust gas from the generator turbine 4 flowing through the turbine exhaust gas path 19, and reference numeral 23 denotes a turbine exhaust gas path 19. The fuel gas preheating heat exchanger 12 heats the fuel gas flowing through the fuel gas supply passage 13 with the flowing turbine exhaust gas, and passes through the exhaust heat recovery passage 24 with the turbine exhaust gas flowing through the turbine exhaust gas passage 19. This is a heat exchanger for exhaust heat recovery that generates hot water or steam by heating flowing hot and cold water. The control unit 8 controls the control valves V2 and V3 in addition to the fuel gas supply amount control valve V1 based on the detected power of the power meter Wm.

[0007]

However, comparing the power generation efficiencies of the fuel cell power generator and the generator, the fuel cell power generator is higher. Therefore, when the specific output is adjusted, the output of the fuel cell power generation unit is adjusted while operating the generator at a substantially constant high output state over the entire range of the specific output adjustment, as in the related art. When adjusting the output,
The smaller the specific output, the larger the ratio of the generator output to the total output of the power generator (hereinafter sometimes simply referred to as the generator output ratio). (Hereinafter, may be referred to as overall power generation efficiency), and improvement has been desired.

As shown in FIG. 4, in order to increase the amount of combustion exhaust gas for driving the generator turbine 4 and the compressor turbine 6, a gas fuel supply passage 20 for supplying gas fuel to the combustion section 2 is provided. When the output of the fuel cell power generation unit 1 becomes small and the amount of combustion exhaust gas becomes insufficient, gas fuel is supplied to the combustion unit 2 in order to replenish the shortage. As the output of the fuel cell decreases, the amount of gas fuel supply increases, so that the overall power generation efficiency is further reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell-based power generation device that can increase the overall power generation efficiency even when the specific output is small.

[0010]

Means for Solving the Problems [Invention according to claim 1]
The characteristic configuration according to claim 1, wherein the turbine for the generator and the turbine for the compressor are provided in a state of being connected in parallel to the combustion unit, and the combustion exhaust gas is discharged from the turbine for the generator and the compression turbine. The present invention is characterized in that a combustion exhaust gas distribution ratio adjusting means for adjusting a distribution ratio to be distributed and supplied to the engine turbine is provided. According to the characteristic configuration of the first aspect, when the specific output is small, the combustion exhaust gas distribution ratio adjusting means adjusts the distribution of the combustion exhaust gas to the turbine for the generator to be small, and the output of the generator is reduced. By reducing the specific power, the specific output is reduced. Therefore, when the specific output is small, the specific output can be reduced while the generator output ratio is made smaller than before, so that even when the specific output is small, the overall power generation efficiency can be increased.

According to a second aspect of the present invention, a fuel gas supply amount adjusting means for adjusting a fuel gas supply amount to the fuel cell power generation unit is provided, and the combustion exhaust gas distribution ratio adjustment is performed. By the means, when the specific output, which is the ratio of the actual output to the total rated output obtained by combining the rated outputs of the fuel cell power generation unit and the generator, is equal to or larger than a set value, the combustion exhaust gas is discharged from the generator turbine. And distributed to both the compressor turbine, and
When the specific output is smaller than the set value, the supply of the combustion exhaust gas to the generator turbine is stopped, and when the specific output is smaller than the set value, the fuel gas supply is stopped. By an amount adjusting means, in order to adjust the output of the fuel cell power generation unit according to the specific output,
The fuel gas supply amount is adjusted. According to the characteristic configuration of the second aspect, when the specific output is smaller than the set value, the supply of the combustion exhaust gas to the generator turbine is stopped by the combustion exhaust gas distribution ratio adjusting means, and the operation of the generator Is stopped, the fuel gas supply amount is adjusted by the fuel gas supply amount adjusting means so as to adjust the output of the fuel cell power generation unit according to the specific output.

That is, such a fuel cell power generation device is
Originally, high efficiency of power generation can be achieved by using the exhaust gas from the fuel cell power generation unit to drive the generator and generate power with the generator, and the generator has a rated output or rated output. Driving at a high output condition close to
Since high power generation efficiency can be obtained, when the specific output is large,
Rather than an operation mode in which the specific output is adjusted by adjusting the output of the generator while operating the fuel cell power generation unit at a high output,
The operation mode in which the specific output is adjusted by adjusting the output of the fuel cell power generation unit while operating the generator in the high output state while effectively using the exhaust gas from the fuel cell power generation unit increases the overall power generation efficiency. can do. Also, the generator is
When operated in a partial load state where the output is smaller than the rated output, the power generation efficiency tends to be further reduced. Therefore, when the specific output is small, even if an operation mode in which the output of the generator is reduced by adjusting the distribution of the combustion exhaust gas to the turbine for the generator by the combustion exhaust gas distribution ratio adjusting means so as to be small, When the supply of the combustion exhaust gas to the generator turbine is stopped and the generator is stopped to operate only the fuel cell power generation unit, the overall power generation efficiency can be further improved.

[0013] Therefore, an operation mode in which the specific output is adjusted by adjusting the output of the fuel cell power generation unit while the generator is operated in the high output state, and the output of the fuel cell power generation unit is adjusted by stopping the generator. By comparing the overall power generation efficiency while reducing the specific output both in the operation mode in which the specific output is adjusted by performing the specific operation, the specific power is higher in the latter operation mode than in the former operation mode. And the specific output is set as the set value. When the specific output is equal to or higher than the set value, the generator is operated in the high output state while operating in an operation mode in which the specific output is adjusted by adjusting the output of the fuel cell power generation unit. When the value is smaller than the set value, the generator is stopped and operated in an operation mode in which the specific output is adjusted by adjusting the output of the fuel cell power generation unit. Therefore, the entire power generation efficiency can be increased in a wide range of the specific output.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the fuel cell power generation device includes a fuel cell power generation unit 1 that is supplied with fuel gas and air as an oxygen-containing gas to generate power, and an exhaust fuel gas discharged from the fuel cell power generation unit 1. Fuel cell power generation unit 1
Burner 2 as a combustion unit that burns with exhaust air (equivalent to exhaust oxygen-containing gas) discharged from the turbine, a generator turbine 4 that drives a generator 3, and air supplied to a fuel cell power generator 1. A compressor turbine 6 that drives a compressor 5 to be pressurized, an inverter 7 that converts DC power generated by the fuel cell power generation unit 1 into AC power, and a control unit 8 that performs various controls of a fuel cell power generation device. And the combustion exhaust gas discharged from the burner 2 drives the generator turbine 4 and the compressor turbine 6.

Then, the output path 9 of the inverter 7 and the output path 10 of the generator 3 are connected to the power transmission path 11, and the DC power generated by the fuel cell power generation unit 1 is converted by the inverter 7. The AC power and the AC power generated by the generator 3 are combined into the power transmission line 11 and supplied to the power demand destination through the power transmission line 11. or,
An exhaust heat recovery heat exchanger 12 is provided that recovers exhaust heat from the combustion exhaust gas after driving the generator turbine 4 and the compressor turbine 6 into the supply water to generate hot water or steam.
That is, the fuel cell power generation device of the embodiment is configured to be able to supply both power and heat.

The fuel cell power generation unit 1 includes a YSZ
It is configured as a solid electrolyte type using a solid electrolyte such as (Y ₂ O ₃ stabilized ZrO ₂ ). Since the solid electrolyte type fuel cell power generation unit 1 is publicly known, detailed description and illustration thereof are omitted, but a cylindrical shape or the like having an oxygen electrode on one surface of the electrolyte layer and a fuel electrode on the other surface is provided. A plurality of flat cells are juxtaposed so that air can be supplied to the oxygen electrode of each cell and fuel gas can be supplied to the fuel electrode of each cell.

Then, the fuel gas supply path 13 for supplying the fuel gas and the air supply path 14 for supplying the air pressurized by the compressor 5 are connected to the fuel cell power generation unit 1 to connect each cell. It is configured to supply fuel gas and air for reaction. Further, an exhaust fuel gas discharge passage 15 for leading the exhaust fuel gas discharged from the cell after contributing to the power generation reaction in the cell, and an exhaust gas for guiding the exhaust air discharged from the cell after contributing to the power generation reaction in the cell. The air passage 16 is connected to the fuel cell power generation unit 1. That is, the fuel gas supplied from the fuel gas supply passage 13 flows on the fuel electrode side of each cell and contributes to the power generation reaction, and then is discharged from each cell as exhaust fuel gas. The air supplied from the air supply passage 14 flows on the oxygen electrode side of each cell, contributes to the power generation reaction, and is discharged from each cell as exhaust air, and is guided in the exhaust air passage 16. It has become.

The fuel cell power generation section 1 is housed in a pressure vessel, and adjusts the pressure of the fuel gas supplied to the fuel electrode side in accordance with the pressure of the air supplied to the oxygen electrode side. The differential pressure applied to the solid electrolyte layer composed of

The fuel gas supply path 13 is provided with a fuel gas supply control valve V1 for controlling the fuel gas supply to the fuel cell power generator 1 in order to adjust the output of the fuel cell power generator 1.

Since the operating temperature of the solid electrolyte type fuel cell power generation unit 1 is as high as 800 to 1000 ° C., the hydrocarbon-based raw fuel gas is converted into hydrogen and water using water vapor inside the cell. It is possible to perform a so-called internal reforming in which a reforming process is performed on a hydrogen-rich reformed gas containing carbon oxide. In view of this, the fuel gas supply path 13 supplies a hydrocarbon-based raw fuel gas such as city gas as fuel gas. Further, a branch path 17 branched from the exhaust fuel gas discharge path 15 is connected to the fuel gas supply path 13 to supply a part of the exhaust fuel gas discharged from the fuel cell power generation section 1 to the fuel cell power generation section 1. By mixing with the raw fuel gas, the water vapor generated by the power generation reaction and contained in the exhaust fuel gas,
The fuel gas is mixed with the fuel gas for reforming. Note that the fuel cell power generation unit 1 has a
A preliminary reformer (not shown) for reforming a part of the raw fuel gas into a reformed gas is provided, and the raw fuel gas containing the reformed gas reformed by the preliminary reformer is supplied to the cell. Then, the raw fuel gas is further internally reformed into a reformed gas in the cell, and hydrogen and carbon monoxide contained in the reformed gas undergo a power generation reaction.

Incidentally, at the fuel electrode, the following reaction formula 1 is obtained by the hydrogen and carbon monoxide in the reformed gas obtained by reforming the raw fuel gas and the oxygen ions passing through the solid electrolyte layer from the oxygen electrode. Power generation reaction at. When the raw fuel gas is, for example, methane gas, the raw fuel gas is composed of water and carbon dioxide contained in the exhaust fuel gas, and water and carbon dioxide generated by the power generation reaction represented by the following reaction formula 1. A reforming reaction is performed according to the following reaction formula 2, and a reformed gas containing hydrogen and carbon monoxide is generated.

[0022]

[Reaction formula 1] H ₂ + O ^2- → H ₂ O + 2e ⁻ , C
O + O ²⁻ → CO ₂ + 2e ⁻ [Reaction formula 2] CH ₄ + H ₂ O → 3H ₂ + CO, CH ₄ +
CO ₂ → 2H ₂ + 2CO

The exhaust gas exhaust passage 15 and the exhaust air passage 16 are connected to the burner 2, and the burner 2 burns the exhaust fuel gas with the exhaust air.

In the present invention, the flue gas supply passage 18 for guiding the flue gas discharged from the burner 2 is branched into a generator turbine passage 18g and a compressor turbine passage 18c, and the generator turbine passage 18c. 18g to the generator turbine 4 and a compressor turbine path 18c.
Is connected to the turbine 6 for the compressor, in other words, the turbine 4 for the generator and the turbine 6 for the compressor are connected in parallel to the burner 2, and the combustion exhaust gas discharged from the burner 2 is used for the generator. It is configured to distribute and supply to the turbine 4 and the compressor turbine 6. As a flue gas distribution ratio adjusting means for adjusting a distribution ratio for distributing and supplying the flue gas to the generator turbine 4 and the compressor turbine 6, an exhaust gas on-off valve V4 is provided in the generator turbine path 18g, The distribution ratio is adjusted by intermittently supplying the combustion exhaust gas to the generator turbine 4 by opening and closing the exhaust gas on-off valve V4.

A turbine exhaust gas path 19g for guiding the exhaust gas discharged from the generator turbine 4 and a compressor exhaust gas path 19c for guiding the exhaust gas discharged from the compressor turbine 6 are connected to a turbine exhaust gas path. The turbine exhaust gas from each of the generator turbine 4 and the compressor turbine 6 is connected to the turbine exhaust gas passage 19 and discharged.

There is a case where the output of the fuel cell power generation unit 1 is reduced to reduce the amount of exhaust fuel gas, resulting in a shortage of combustion exhaust gas for driving the turbine 4 for the generator and the turbine 6 for the compressor. A gas fuel supply path 20 for supplying gas fuel such as city gas to the burner 2 is connected to the burner 2 for replenishing the combustion exhaust gas at that time, and the amount of gas fuel supplied to the gas fuel supply path 20 is adjusted. A gas fuel supply amount control valve V2 is provided.

When the amount of compressed air discharged from the compressor 5 is larger than the amount corresponding to the output of the fuel cell power generation unit 1, a surplus larger than the amount corresponding to the output bypasses the fuel cell power generation unit 1. In order to supply the air to the burner 2, an air bypass passage 21 branched from the air supply passage 14 is connected to the burner 2,
The air bypass passage 21 is provided with an air bypass amount adjusting valve V3 for adjusting the air bypass amount.

The heat exchange between the turbine exhaust gas flowing through the turbine exhaust gas passage 19 and the air flowing through the air supply passage 14 to heat the air flowing through the air supply passage 14, A heat exchanger for preheating fuel gas, which heat-exchanges the turbine exhaust gas flowing through the turbine exhaust gas passage 19 and the fuel gas flowing through the fuel gas supply passage 13 to heat the fuel gas flowing through the fuel gas supply passage 13. 23, turbine exhaust gas flowing through turbine exhaust gas passage 19 and exhaust heat recovery passage 24
The heat exchange between the heat exchanger and the hot water flowing through the exhaust heat recovery passage 24 is performed to heat the hot water flowing through the exhaust heat recovery passage 24 to generate hot water or steam. 19 are arranged so as to line up from the upstream side to the downstream side.

The power transmission line 11 is provided with a power meter Wm for measuring the power output from the fuel cell power generator.

The control unit 8 controls the fuel gas supply amount control valve V1, the gas fuel supply amount control valve V2, the air bypass amount control valve V3, and the exhaust gas on-off valve V3 based on the power detected by the wattmeter 8.
It is configured to control each of the four. Hereinafter, the control unit 8
Will be described. When the specific output R, which is the ratio of the actual output to the total rated output obtained by combining the rated outputs of the fuel cell power generation unit 1 and the generator 3, is equal to or greater than the set value Rs, the control unit 8 controls the exhaust gas on-off valve V Is controlled to control the fuel gas supply amount adjusting valve V1 so as to adjust the fuel gas supply amount so as to adjust the output of the fuel cell power generation unit 1 according to the specific output R, When the output R is smaller than the set value Rs, the exhaust gas on-off valve V4 is kept closed and the fuel gas supply amount is adjusted to adjust the output of the fuel cell power generation unit 1 according to the specific output R. Thus, the fuel gas supply amount control valve V1 is controlled.

That is, when the specific output R is equal to or higher than the set value Rs, the combustion exhaust gas is distributed and supplied to both the generator turbine 4 and the compressor turbine 6 and the generator 3 is operated at the rated output. The fuel cell / generator parallel operation is performed in an operation mode in which the specific output R is adjusted by adjusting the output of the fuel cell power generation unit 1. When the specific output R is smaller than the set value Rs, the generator turbine 4 In this state, the supply of the combustion exhaust gas to the fuel cell is stopped and the output of the fuel cell power generation unit 1 is adjusted in a state where the generator 3 is stopped.

FIGS. 2 and 3 show that in the fuel cell power generator constructed as described above, the fuel cell / generator parallel operation and the fuel cell independent operation are executed while changing the specific output R. In each operation, the relationship between the specific output R and the overall power generation efficiency was examined. The fuel cell power generation unit 1 was operated with the fuel utilization set at 80%. The rated output of the fuel cell generator 1 is 800 kW, the rated output of the generator 3 is 224 kW, and the auxiliary power consumed inside the power generator by the auxiliary is 30 kW. The total rated output including the rated output of each of the units 3 is the rated output of the fuel cell power generation unit 1 of 800 kW.
It is 994 kW obtained by subtracting the auxiliary power 30 kW from the sum of the rated output 224 kW of the generator 3. In FIG. 2, the total electric output is electric power output from the power transmission line 11 and is measured by the power meter Wm, and corresponds to an actual output from the power generation device. Therefore, the specific output R is indicated by a value obtained by dividing the total electric output by the total rated output of 994 kW. The total power generation efficiency is a value obtained by dividing the total electric output by the total supply heat amount (lower heat generation standard), and the total supply heat amount is determined by the fuel gas supply amount control valve V1 and the heat amount of the fuel gas supplied. Further, the calorific value of the gas fuel supplied and adjusted by the gas fuel supply amount adjusting valve V2 is added.

FIG. 3 is a graph showing the relationship between the specific output and the overall power generation efficiency in each of the fuel cell / generator parallel operation and the fuel cell independent operation. In FIG. 3, assuming that a specific output Rs (for example, 0.55) corresponding to the intersection of the line indicating the relationship in the fuel cell / generator parallel operation and the line indicating the relationship in the fuel cell alone operation, the specific output R
Is larger than Rs, the fuel cell / generator parallel operation has higher overall power generation efficiency, and when the specific output R is smaller than Rs, the fuel cell alone operation has higher overall power generation efficiency. Therefore, the specific output Rs corresponding to the intersection of the line indicating the relationship in the fuel cell / generator parallel operation and the line indicating the relationship in the fuel cell independent operation is set to the set value.

That is, when the specific output R is equal to or higher than the set value Rs, the fuel cell / generator using the fuel cell according to the present invention selects the fuel cell / generator parallel operation in which the overall power generation efficiency is higher than the fuel cell single operation. When the specific output R is smaller than the set value Rs, the fuel cell single operation in which the overall power generation efficiency is higher than the fuel cell / generator parallel operation is selected. On the other hand, in the conventional fuel cell power generation device, the fuel cell / generator parallel operation is performed over the entire adjustment range of the specific output R. Therefore, when the specific output R is smaller than the set value Rs, the fuel cell power generation device according to the present invention can be operated in a state in which the overall power generation efficiency is higher than in the related art.

In the fuel cell / generator parallel operation, the fuel cell power generation unit 1 is operated while the generator 3 is operated at the rated output.
Since the specific output R is adjusted by adjusting the output of
The generator 3 can be driven at the rated output,
It is necessary for the burner 2 to generate a sufficient amount of combustion exhaust gas to supply air to the compressor 5 at a pressure capable of appropriately controlling the differential pressure applied to the solid electrolyte layer in the fuel cell power generation unit 1. is there. In the following description,
A state in which the compressor 5 is driven to supply air at a pressure that can appropriately control the differential pressure applied to the solid electrolyte layer in the fuel cell power generation unit 1 may be referred to as a fuel cell differential pressure corresponding drive. Therefore, in the fuel cell / generator parallel operation, by reducing the output of the fuel cell generator 1 in accordance with the specific output R, the amount of fuel gas exhausted from the fuel cell generator 1 is reduced, and the generator 3 is If the burner 2 does not generate the required amount of combustion exhaust gas to drive the compressor 5 at the rated output and drive the compressor 5 corresponding to the fuel cell differential pressure, the control unit 8 can generate the required amount of combustion exhaust gas. Thus, the gas fuel supply amount control valve V2 is controlled to supply the gas fuel to the burner 2.

In the fuel cell single operation, the specific output R is adjusted by adjusting the output of the fuel cell power generation unit 1 with the generator 3 stopped. Therefore, in the fuel cell independent operation, by reducing the output of the fuel cell power generation unit 1 in accordance with the specific output R, the amount of fuel gas exhausted from the fuel cell power generation unit 1 decreases, and the compressor 5 When the burner 2 does not generate the required amount of combustion exhaust gas for the pressure-dependent driving, the control unit 8 controls the gas fuel supply amount control valve V so that the required amount of combustion exhaust gas can be generated.
2 is controlled to supply gas fuel to the burner 2.

The gas fuel supply amount in each of the fuel cell / generator parallel operation and the fuel cell independent operation is set in advance in correspondence with the specific output and stored in the control unit 8.

When operating at a high specific output in the fuel cell / generator parallel operation or when switching from the fuel cell / generator parallel operation to the fuel cell independent operation, the compressor 5
The amount of air discharged from the fuel cell power generation unit 1 may be larger than the amount of air required in the fuel cell power generation unit 1. In such a case, the control unit 8 controls the excess air to be supplied to the burner 2 by the control unit 8. The air bypass amount control valve V3 is controlled. The surplus air amount is set in advance in correspondence with the specific output and stored in the control unit 8.

As described above, the fuel cell power generation unit 1 is constituted by a solid electrolyte fuel cell whose power generation reaction is as high as about 800 to 1000 ° C., so that the fuel discharged from the fuel cell power generation unit 1 is discharged. Since the gas and the exhaust air have a high temperature equivalent to the power generation reaction temperature, the generator turbine 4 can be driven by the high temperature combustion exhaust gas, and the power generator 3 has high power generation efficiency and high output. Power generation can be performed. Therefore, it has become possible to provide a fuel cell power generation device that has a high output and can increase the overall power generation efficiency even when the specific output is small.

[Another Embodiment] Next, another embodiment will be described. (A) In the above embodiment, the exhaust gas on-off valve V4 is provided on the generator turbine path 18g as the flue gas distribution ratio adjusting means, and the exhaust gas on-off valve V4 is opened and closed to operate the generator turbine. The case where the distribution ratio is adjusted by intermittently supplying the combustion exhaust gas to No. 4 has been exemplified. Instead, a proportional valve is provided as one or both of the generator turbine path 18g and the compressor turbine path 18c as a combustion exhaust gas distribution ratio adjusting means, and the generator valve is provided by the proportional valve. The distribution ratio may be adjusted by adjusting the supply amount of the combustion exhaust gas to the utility turbine 4 stepwise or continuously. in this case,
When the specific output R is small, the output of the generator 3 is adjusted while the output of the fuel cell power generator 1 is kept constant, so that the specific output R can be adjusted or the fuel cell power generator 1 and the power generator can be controlled. By adjusting the output of each machine 3,
Adjust the specific output R. Also in this case, the generator output ratio can be made smaller than in the past, so that the overall power generation efficiency can be increased.

(B) The fuel gas supplied to the fuel cell power generation section 1 through the fuel gas supply path 13 is not limited to the hydrocarbon-based raw fuel gas exemplified in the above embodiment. For example, a hydrogen-rich reformed gas obtained by previously reforming a hydrocarbon-based raw fuel (a liquid raw fuel such as gasoline, methanol, and ethanol, or a gaseous raw fuel such as methane and propane) with steam is used. A mixed gas of a reformed gas and a hydrocarbon-based raw fuel gas may be used. Alternatively, pure hydrogen gas may be used.

(C) The type of the fuel cell power generation section 1 is not limited to the solid electrolyte type as exemplified in the above embodiment, but is a molten carbonate type using a molten carbonate as an electrolyte, and an electrolyte. May be a phosphoric acid type using phosphoric acid, and a solid polymer type using a solid polymer as an electrolyte. However, in order to cause the generator 3 to generate power with high power generation efficiency and high output to obtain high output, the present invention is applied to a solid electrolyte type or a molten carbonate type fuel cell having a high power generation reaction temperature. Is preferred.

[Brief description of the drawings]

FIG. 1 is a system diagram of a power generation device using a fuel cell according to an embodiment.

FIG. 2 is a diagram showing the relationship between specific output and overall power generation efficiency in each of fuel cell / generator parallel operation and fuel cell independent operation.

FIG. 3 is a diagram showing the relationship between specific output and overall power generation efficiency in each of fuel cell / generator parallel operation and fuel cell independent operation.

FIG. 4 is a system diagram of a conventional fuel cell power generation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell power generation part 2 Combustion part 3 Generator 4 Turbine for generator 5 Compressor 6 Turbine for compressor V1 Fuel gas supply amount adjusting means V4 Combustion exhaust gas distribution ratio adjusting means

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hisao Yokoyama 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka Gas Co., Ltd. 5H027 AA06 BC11 DD01

Claims (2)

[Claims] 1. A fuel cell power generation section that is supplied with a fuel gas and an oxygen-containing gas to generate electric power, and converts exhaust fuel gas discharged from the fuel cell power generation section into exhaust oxygen-containing gas discharged from the fuel cell power generation section. A combustion unit that drives the generator, a turbine for a generator that drives a generator, and a turbine for a compressor that drives a compressor that pressurizes the oxygen-containing gas supplied to the fuel cell power generation unit. A fuel cell-based power generator configured to drive the generator turbine and the compressor turbine with the discharged combustion exhaust gas, wherein the generator turbine and the compressor turbine include: A combustion exhaust gas distribution that is provided in parallel with the combustion unit and that adjusts a distribution ratio at which the combustion exhaust gas is distributed and supplied to the generator turbine and the compressor turbine; A fuel cell-based power generation device provided with a ratio adjusting means. 2. A fuel gas supply amount adjusting means for adjusting an amount of fuel gas supplied to the fuel cell power generation unit, and a rated output of each of the fuel cell power generation unit and the generator by the combustion exhaust gas distribution ratio adjusting means. When the specific output, which is the ratio of the actual output to the total rated output, is equal to or greater than a set value, the combustion exhaust gas is distributed and supplied to both the turbine for the generator and the turbine for the compressor, and When the specific output is smaller than the set value, the supply of the combustion exhaust gas to the generator turbine is stopped. When the specific output is smaller than the set value, the fuel gas supply amount is reduced. 2. The fuel gas supply amount according to claim 1, wherein the adjusting means adjusts the fuel gas supply amount so as to adjust the output of the fuel cell power generation unit in accordance with the specific output. Charge the battery using power generation equipment.