JPH0782869B2 - Molten salt fuel cell power plant - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a molten salt fuel cell power plant, and is particularly suitable for maintaining the output characteristics of the power plant at high performance and stability over a long period of time. Molten salt fuel cell power plant.

[Conventional technology]

Molten salt fuel cells use alkali metal carbonate as electrolyte
It is a fuel cell of a type that operates at a high temperature of 600 to 700 ° C. At an operating temperature, carbonate is in a molten state, and carbonate ion (CO ₃ ²⁻ ) plays a role as an ion conductor. The basic structure of the cell is such that an anode (fuel electrode) and a cathode (oxidizer electrode), which are electrodes, are arranged on both sides of an electrolyte plate in which the above-mentioned electrolyte is held on an electrolyte substrate, and the fuel gas chamber and the oxidizer are arranged outside them. A predetermined battery voltage is obtained by forming a block of a laminated battery in which a plurality of agent gases are provided and a plurality of these are laminated as a unit battery. In order to increase the capacity of the laminated battery, the electrode area is increased so that a large current can flow. A fuel cell is a high-efficiency DC generator that can directly convert chemical energy into electric energy by causing an electrochemical reaction by supplying a fuel gas and an oxidant gas to the above chambers.
In the molten salt fuel cell, a gas containing hydrogen (H ₂ ) or hydrogen and generalized carbon (CO) is used as a fuel gas in the fuel gas chamber, and oxygen (O ₂ ) and carbon dioxide (CO ₂ ) are used as oxidant gases. By supplying the gas containing ₂ ) to the oxidant gas chamber, the following electrochemical reactions proceed, and an electric current can be taken to the outside.

2H ₂ ＋ 2CO ₃ ^2- → 2CO ₂ ＋ 2H ₂ O ＋ 4e… (1) Formula 2CO ₂ ＋ O ₂ ＋ 4e → 2CO ₃ ²・ ・ ・ (2) Formula In this electrochemical reaction, the electrolyte and the above reaction gas coexist on the electrode surface. It is considered that the reaction proceeds at a so-called three-phase interface, and if the electrochemical reaction can proceed smoothly and at a sufficient speed, high battery performance can be maintained. For that purpose, it is important to secure a sufficient reaction field in the electrode called a three-phase interface. That is, it is necessary that the electrode has a large specific surface area, that the surface of the electrode is appropriately wet with the electrolyte, and that the pores of the electrode are optimized to smoothly diffuse the reaction gas in the pores. As a control method for maintaining a wide reaction field, for example, in a phosphoric acid fuel cell, water repellency control, pore adjustment control and the like can be mentioned. The former method is a method of controlling the wettability of phosphoric acid with respect to the electrode by appropriately presenting a water repellent agent represented by polytetrafluoroethylene in the electrode catalyst.
In a molten salt fuel cell, a suitable material corresponding to the water repellent is not used, and the characteristic control of the cell member for maintaining the three-phase interface in the molten salt fuel cell is limited to the pore adjustment control method. The relationship between the electrode pore size and the electrolyte substrate pore size is described in, for example, DEVELOPMENT OF MOLTEN CARBONATE FUEL CELLS F (DEVELOPMENT OF MOLTEN CARBONATE FUEL CELLS FELL).
OR POWER GENERATION) (Published by the United States Department of Energy in April 1980), the pore size of the electrolyte substrate is generally about 1 digit smaller than the pore size of the electrode, and the average pore size is usually 1 micron or less. In contrast, the electrode pore size typically has an average pore size of 3-10 microns. As a result, the electrolyte holding power of the electrolyte substrate becomes higher than that of the electrode, and the electrode is prevented from being overwetted by the electrolyte and, by extension, gas diffusion failure due to clogging of the electrode pores by the electrolyte. However, on the other hand, there is a possibility that the electrolyte migration to the electrode surface is hindered and the wet state by the electrolyte becomes insufficient, the field of the electrochemical reaction becomes insufficient, and the ion diffusion resistance increases.

As a method other than such a pore adjustment control method, there is an electrolyte storage method in the electrode pores. In advance, a predetermined amount of electrolyte is held in the pores of the anode and / or cathode, which is an electrode, within a range that does not affect gas diffusion.
This is a method of incorporating this in a battery, and by doing so, the electrochemical reaction field is optimized to achieve high performance of the battery and to extend the service life.

As described above, various means and methods have been applied in order to improve the performance and extend the life of the molten salt fuel cell. However, in addition to these, the battery assembly accuracy, the battery operating method, etc. There are many factors that cause the performance to appear, and I have often experienced that it takes a long time from the start of power generation until the rated output is reached. Furthermore, the pore characteristics of the electrolyte substrate and electrodes change with the course of long-term operation, and the state of existence of the electrolyte changes accordingly, which reduces the electrochemical reaction field and decreases the battery performance. There are also problems.

As a conventional technique from the viewpoint of extending the life of the fuel cell, a method of increasing the pressure of the fuel gas and the oxidant gas when the load increases and decreasing the pressure of each gas to be supplied when the load decreases (Japanese Patent Laid-Open No. Sho 60). No. -10566), the active materials supplied to the positive and negative electrodes of the fuel cell are exchanged with each other, and the power generation method of converting the positive and negative electrodes of the cell is performed at least once (JP-A-60-189177).
No.), a method of suppressing evaporation / diffusion of the electrolyte by adding an electrolyte to the gas supplied to the cathode or the anode (Japanese Patent Laid-Open No. 61-24166).

[Problems to be solved by the invention]

The above-mentioned prior art has improved the characteristics of various cell constituent members until a molten salt fuel cell stack, that is, a block formed by stacking a plurality of unit cells or a stack as an assembly thereof is formed. Although it is the culmination of technology, due consideration has not been given to the operation method of assembled batteries and the control method for maintaining battery performance, and it is difficult to suppress deterioration of battery performance by external means. There was a problem.

Reactive gas pressure adjustment control, battery operating temperature control, reactive gas partial pressure control, etc. are generally used to improve battery performance. However, in the case of the reactive gas pressure adjustment control, the differential pressure between the anode and the cathode cannot be increased so much. There is a limit to the bubble pressure resistance of the battery, and if it exceeds it, a gas crossover phenomenon will occur and the battery will be damaged. Further, the pressure difference between the anode and / or the cathode and the pressure inside the belzier cannot be increased so much. If the differential pressure is set too high, the gas sealing characteristics will be deteriorated, the reaction gas will leak to the outside of the battery, and the reaction gas utilization rate will decrease, resulting in a decrease in power generation efficiency. If it flows in, the partial pressure of the reaction gas is lowered, and the battery performance is lowered.

On the other hand, in the case of controlling the battery operating temperature, increasing the battery operating temperature also increases the rate of electrolyte ion diffusion and reaction gas diffusion, reduces the specific resistance of the battery members, and changes the leakability of the electrode electrolyte. The electrode / electrolyte plate interface state changes and the electrochemical reaction rate often increases, but if the battery operating temperature is too high, corrosion of the battery material is promoted. Is also promoted, and the evaporation of the electrolyte is promoted.

In the case of controlling the partial pressure of the reaction gas, increasing the H ₂ and / or CO partial pressure in the fuel gas and the O ₂ and CO ₂ partial pressures in the oxidant gas will certainly improve the cell performance. As in the present invention, it is not easy to arbitrarily increase the reaction gas partial pressure in a molten salt fuel cell power plant using a steam reformer or a coal gasifier and a fuel cell main body in combination. Speaking of which, it is possible to lower the partial pressure of water vapor and increase the partial pressure of the reaction gas by gas-liquid separation, but this is very limited from the one suppressing condition of preventing carbon precipitation in the battery body. is there. Furthermore, if it becomes a large-capacity power plant, in addition to the above reformer and gasifier, H
It is not practical to provide _two sources, O ₂ source or CO ₂ source separately.

As described above, the reactive gas pressure adjustment control, the battery operating temperature control, or the reactive gas partial pressure control is not a method that can fundamentally improve the characteristics of the battery main body, but the battery performance temporarily increases due to these external factors. However, if these conditions are restored, the battery performance is also restored, or rather, the battery body is generally damaged and a bad characteristic state is brought about.

The object of the present invention is to solve the drawbacks of the prior art, improve the characteristics of the fuel cell itself, and maintain the output characteristics of the power plant at high performance and stability over a long period of time. To provide a power plant.

[Means for solving problems]

In order to achieve the above object, it is important to secure a sufficient reaction field in the electrode as described above, and it is necessary to optimize the existing state of the electrolyte on the electrode surface and the electrode / electrolyte plate interface. When the battery performance is difficult to develop or the battery performance has deteriorated, the presence state of the electrolyte is often unsuitable, and the electrolyte is biased to the anode side or the cathode side. Is often caused.

The present inventors changed the electrolyte existence state by a simple operation process from the outside, and made various attempts for the purpose of improving the battery characteristics by making the unbalanced state an appropriate existence state, as a result, The present invention has been provided.

In a fuel cell of the type that uses a molten carbonate as an electrolyte, when the cell performance is difficult to express, or when the cell performance has deteriorated, the reaction gas supply amount is reduced or cut off under a load on the cell, It was clarified that the battery voltage becomes higher than that before the treatment by the extremely simple operation of maintaining the state for a certain period of time and then returning to the original state again. More specifically, the hydrogen-containing gas, which is the fuel gas supplied to the anode, is temporarily shut off or the supply amount thereof is reduced to carry out the above operation. Further, the above-mentioned operation is carried out by shutting off the O ₂ and CO ₂ containing gas which is the oxidant gas supplied to the cathode or by reducing the supply amount thereof. Further, both the fuel gas supplied to the anode and the oxidant gas supplied to the cathode may be temporarily shut off or the supply amount thereof may be reduced to carry out the above operation.

The present invention provides a method for recovering the output characteristics of a melt-type fuel cell power generation plant by incorporating the above operation as a plant operation control mechanism when the output characteristics are reduced, and for a long period of time. High performance and stable output characteristics are maintained.

[Action]

More specifically, the function and effect of the present invention will be described. One example is when the fuel gas supplied to the anode is shut off or the supply amount is reduced.

When H ₂ in the fuel gas is not supplied or is insufficient, it is expected that the following reaction will proceed on the anode side.

2CO ₃ ^2- → 2CO ₂ + O ₂ + 4e (3) Formula 2CO ₃ ^2- + 2M → 2CO ₂ + 2MO + 4e (4) Formula Here, M means a metal used on the anode side.

Oxygen is generated at the anode, and as a battery at the cathode.
Pumping the O _2, O ₂ is generated at the anode, it believed to function as a so-called oxygen pumping and is also expected film formation by oxidation of the cell material M. In any case, from the normal battery reaction in which the above equations (1) and (2) proceed,
When the reaction at the anode changes to the equation (3) or (4), the anode potential changes. It can be presumed that this sudden change in potential causes a movement phenomenon of the electrolyte, improves the state of wetting of the electrode by the electrolyte, increases the electrochemical reaction field, and improves the battery characteristics.

Further, as described above, it is expected that the surface modification of the battery material, particularly the electrode by forming an oxide film, changes the electrolyte wetting characteristics and exerts an effect of increasing the electrochemical reaction field.

Another example is when the O ₂ and CO ₂ containing gas supplied to the cathode is shut off or the supply amount is reduced.

The reaction on the cathode side when CO ₂ in the oxidant gas is not supplied or is insufficient, is not clear,
The following reactions are expected to proceed.

^{_{4O 2 + 4e → 4O 2 -}} ... (5) formula _{8MO + 4e → 8M + 4O 2} - ... (6) reduction of metal oxide MO is the reaction and the electrode material to generate a peroxide or superoxide due to ionization of O ₂ in the formula cathode It is a reaction. It is considered that the progress of such a reaction causes a potential change at the cathode, and the wet state of the electrode changes due to the movement of the electrolyte, thereby improving the battery characteristics. Further, it is expected that the surface modification of the cathode also changes the wetting characteristics of the electrode with the electrolyte, leading to an increase in the electrochemical reaction field in some cases.

As described above, by blocking one or both of the reaction gas supplied to the anode and / or the cathode or reducing the supply amount, the potential change of the anode and / or the cathode occurs, and the state of the interface between the electrode and the electrolyte plate is changed. Change, the reaction system of the electrification system changes, it is difficult to develop battery performance,
When the performance decreases, it often works to improve the battery characteristics, and the effect is remarkable.

Electroosmotic electrochemical measurement method already known as one of electrokinetic phenomena (Fujishima, Aizawa, Inoue; Gihodo Publishing)
46-47), that is, there is a sufficient possibility that a pressure difference is generated by using the potential difference as a driving force to move the electrolyte liquid phase.

The inventors of the present invention have used other types of fuel cells such as methanol / air fuel cells and phosphoric acid fuel cells so far.
Potential sweep (operation to swing the potential for one cycle or more)
It has been confirmed that the wetting characteristics of the electrode electrolyte are changed by means of forcibly applying a potential difference or a potential difference, and it is considered that the electroosmosis phenomenon is effectively acting, but in the molten salt fuel cell, It was found that the operation of shutting off one or both of the reaction gases or reducing the supply amount, as in the present invention, has a significant effect on the improvement of the battery characteristics, as compared with the case of simply performing the operation of sweeping the potential or applying the potential. It was

In carrying out the operation according to the present invention, it is preferable that a load current flows through a block formed by stacking a plurality of unit batteries or a cell stack in which these unit batteries are assembled, which is highly effective in manifesting battery performance. Although the load current value is not particularly limited, when the load current value is large, high battery performance is exhibited even by short-time operation of shutting off the reaction gas or reducing the supply amount. For example, when a constant current having a current density of 150 mA / cm ² is forcibly loaded, the above-mentioned operation can be effective for about 1 minute to several minutes. However, it has been confirmed that even at a current density of 50 mA / cm ² or less, the effect can be exhibited by taking a little longer time of several minutes to several tens of minutes.

In carrying out the operation of the present invention, initially, the power was forcibly energized so that a constant current could flow. In that case, it is possible to energize the entire stack of stacked batteries, or to block the stacked batteries so that a predetermined current can be flowed only to the blocks with reduced output characteristics. In the present invention, of course, this method can be adopted, but in the conventional case, the cell stack has a larger area and higher stacking, and for example, the area is 10,000 cm ²
When (1 m ^□) in the Natsuta, if the current density is 150 mA / cm ² applied current is 1500A, and the to the constant current load power of a large capacity is required, for example, lamination number of Serusutatsuku 600
Assuming that a stack of 40 stages and 1 block has 40 stacked layers and 15 blocks, the control mechanism is complicated because a predetermined current is passed only to the blocks whose output characteristics are deteriorated. However, it can be implemented. In carrying out the method of the present invention, the inventors of the present invention investigated the effect on the cell characteristics when a normal load other than a constant current load power source was connected, and based on the results of the investigation, the molten salt fuel cell power generation of the present invention The effectiveness of the plant operation method was verified.

The present invention is characterized in that it has an anode and a cathode, a molten carbonate is used as an electrolyte, carbonate ions are used as a conductor, and a fuel gas is supplied to the anode and an oxidant gas is supplied to the cathode as a reaction gas. Type fuel cell power plant, when operating with a load connected to the fuel cell, if the output of the fuel cell drops below the preset output from the rated value, the fuel gas supplied to the anode of the main body of the fuel cell Is supplied to the anode, and means for suppressing the supply amount of the fuel gas for a predetermined time so as to change the pressure of the reaction gas so that the amount becomes smaller than the electrochemical equivalent of the current flowing in the fuel cell main body. Means for introducing surplus fuel gas into the combustor by bypassing the battery body, and surplus combustion exhaust gas from the combustor, turbine generator and exhaust heat recovery device In that it comprises a means for supplying at least one.

〔Example〕

Hereinafter, the content of the present invention will be described in more detail based on a schematic system diagram.

FIG. 1 shows a molten salt fuel cell power plant in which the steam reforming apparatus 1 is installed as a fuel gas production apparatus. During normal power generation, fuel gas is supplied to the anode of the fuel cell main body 2 from the reforming section of the steam reforming apparatus 1 through the pipes 3 and 4. On the other hand, the anode outlet gas of the fuel cell main body 2 is introduced into the furnace part of the steam reforming apparatus 1 through the pipe 5 together with a predetermined amount of air and burns, and the heat is used as a heat source to the reforming part. This figure is a basic schematic system diagram of a clean fuel system power plant with a steam reformer.
In practice, if the combustion heat of the anode outlet gas is insufficient as a heat source for the reforming section, a part of the raw fuel LNG may be supplied to the furnace section as an auxiliary fuel. Carbon dioxide-containing gas, which is combustion exhaust gas, is supplied to the cathode of the fuel cell main body 2 through the pipes 6, 7, and 8 and air through the pipe 8 rather than the furnace portion of the steam reforming apparatus 1. The supply amount of these reaction gases is controlled to a predetermined flow rate according to the load current amount, which is the power generation condition, the reaction gas utilization rate, and the like. The cathode outlet gas of the fuel cell main body 2 is introduced into the exhaust heat recovery apparatus 10 through the pipe 9, and steam is generated by heat exchange with the water supplied to the exhaust heat recovery apparatus 10 as well, and then out of the system through the pipe 11. Is discharged. In a real plant,
A part of the cathode outlet gas may be used as a cycle gas by the compressor for cooling the fuel cell body 2, and is generally introduced into the turbine compressor and used as a gas source for air compression and turbine power generation. However, it is omitted in this figure. Usually, the exhaust heat recovery device 10 is installed in the subsequent stage. The steam generated in the exhaust heat recovery apparatus 10 is supplied to the steam reforming section of the steam reforming apparatus 1 through the pipes 12 and 13, and LNG as a raw fuel is supplied to the steam reforming unit 1 through the pipe 13 at a predetermined ratio with the steam. The reforming reaction produces a hydrogen containing gas with the fuel gas to the anode.

The direct current electricity generated by the fuel cell main body 2 is converted into alternating current by the inverter 13 and is transferred to the power system line.

Battery voltage, power, internal resistance, etc. are the most representative indicators that indicate that the output characteristics of a fuel cell power plant have deteriorated. Further, it is possible to use the polarization value of the arbitrarily selected specific cell as an index. In this case, by comparing the magnitudes of the anodic polarization and the cathodic polarization, it becomes possible to effectively determine whether the supply amount of the fuel gas or the oxidant gas should be reduced or the shutoff operation should be performed. However, in this case, there is also a disadvantage that a large number of index value detection terminals must be provided.

As an example, it is assumed that the battery voltage is used as an index and a value of 70% of the rated voltage is set. This value is stored in the computer. Also, if necessary, for example 90% of rated voltage (output)
The setting value can be changed as desired. This index detection terminal, in this example the battery voltage detection terminal, can be provided for each block formed by stacking a plurality of unit batteries, and the detection can be performed for each cell stack where these are assembled in a large-capacity centralized power plant. Terminals can also be provided. In that case, it is preferable to provide a control mechanism for reducing or interrupting the supply amount of the reaction gas for each block or each cell stack.

When the battery voltage of the block or cell stack, which is an index, falls below the set value, the control mechanism of the cell block or cell stack that has fallen below the set value operates and the fuel gas supplied to the anode and / or the oxidant gas supplied to the cathode After the supply amount of air and carbon dioxide gas is reduced or cut off for a certain period of time, the original state is restored again. The type and time of the reaction gas for reducing the supply amount or shutting off the supply gas can be arbitrarily set and stored in the computer. Moreover, the setting conditions can be arbitrarily changed as needed. It is also possible to repeat the operation of reducing the supply amount of fuel gas or shutting off the fuel gas several times.
It is also possible to repeat the operation of reducing or shutting off the supply of oxidant gas several times, but usually the most effective procedure is to first reduce or shut off the supply of fuel gas, and then supply the carbon dioxide-containing gas in the oxidant gas after restoration. After reducing or shutting off the amount of air, and returning to it again, reduce the amount of air supply or shut off the air, and restore it three times. By this operation, the supply amount reduction or interruption operation is repeated again for the reaction gas having the largest battery voltage gain, and this operation is completed when the battery voltage gain is exhausted. This control step is merely an embodiment and can be arbitrarily set, and programming related to the battery voltage gain is also possible. The time for reducing or shutting off the supply amount can be set arbitrarily, but it is preferably about 1 to 3 minutes.

The supply amount of the reaction gas is reduced or cut off at a predetermined rate lower than the electrochemical equivalent based on the current flowing in the fuel cell main body 2. For example, the electrochemical gas equivalent fuel gas amount required for a cell block of a 40-layer stacked unit cell in which a current of 1000 A is flowing is such that the total amount of hydrogen (H ₂ ) and generalized carbon (CO) contained in the gas is 16.8. The supply amount is Nm ³ / h. In the case of carbon dioxide-containing gas that is an oxidant gas, the amount of carbon dioxide (CO ₂ ) contained in the gas is 1
The supply amount is 6.8 Nm ³ / h, and the air amount is 40 Nm.
³ / h. It is equipped with a control mechanism that reduces the supply rate to a predetermined rate smaller than this electrochemical equivalent, and in the case of a cell block or cell stack that has fallen below the set value of the cell voltage as an index, it is linked with the current value flowing in the fuel cell body 2. Then, each reaction gas supply amount control mechanism operates.
For example, the fuel gas supply amount is reduced or cut off by the fuel gas flow control valve 14. When it is set to 1/2 of the electrochemical equivalent, the flow rate of the fuel gas supplied to the anode of the fuel cell body 2 is reduced to half of the above flow rate. Further, if the setting is set to zero, the supply of fuel gas to the anode is cut off. Excess fuel gas is bypassed via pipe 15. The bypassed fuel gas is introduced into a separately provided combustor, and its combustion exhaust gas is supplied to the turbine generator or the exhaust heat recovery device 10 to recover its energy and heat quantity. In addition, the energy and the amount of heat of the steam reforming apparatus 1 can be similarly recovered by introducing them into the furnace section and burning them. Alternatively, the gas may be inserted into a fuel gas tank and reused again for fuel cell power generation.

Further, as another method of reducing the fuel gas supply amount, it is possible to control the supply amounts of LNG and steam, which are raw fuels to be supplied to the steam reforming apparatus 1.

On the other hand, the supply amount of the carbon dioxide gas containing gas supplied to the cathode of the fuel cell main body 2 is reduced or cut off by the combustion exhaust gas flow rate control valve 16 by the same control mechanism as the fuel gas flow rate control valve 14. The surplus gas of the combustion exhaust gas is discharged from the pipe 17, and the gas is also supplied to the turbine generator or the exhaust heat recovery device 10 and the energy and heat amount thereof can be recovered as in the case of the surplus fuel gas.

Further, the reduction or interruption of the supply amount of the air supplied to the cathode of the fuel cell main body 2 is performed by the air flow rate control valve 18 by the same control mechanism as described above.

FIG. 2 shows a molten salt fuel cell power plant in which the coal gasification device 19 is installed as a fuel gas production device. The difference from FIG. 1 is that a coal gasification device 19 is provided instead of the steam reforming device 1, and a gas purification device 20 is provided along with it. In addition, a combustor 21 is provided for combusting the anode outlet gas and supplying the carbon dioxide-containing gas that is the combustion gas to the cathode. Along with this, air and excess fuel gas are introduced into the combustor 21. A pipe 8'and a pipe 15 'are provided for this purpose.

The control operation method of this power plant is based on the method described above with reference to FIG. It goes without saying that the gas turbine and / or the steam turbine generator can be installed and operated also in this plant.

〔The invention's effect〕

According to the present invention, in a fuel cell power plant of the type that uses molten carbonate as an electrolyte and carbonate ions as a conductor,
If the battery performance is difficult to develop or the output characteristics have deteriorated, the characteristics can be restored in a short time by extremely simple operation from the outside, and high performance is achieved over a long period of time. This has the effect of maintaining stable output characteristics.

[Brief description of drawings]

FIG. 1 is a clean fuel LN showing one embodiment of the present invention.
Fig. 2 is a basic system diagram of a molten salt fuel cell power plant using G as a raw fuel, and Fig. 2 is a basic system diagram of a molten salt fuel cell power plant using coal as a raw fuel. 1 ... Steam reforming device, 2 ... Fuel cell main unit, 10 ... Exhaust heat recovery device, 13 ... Inverter, 14 ... Fuel gas flow control valve, 16 ... Combustion exhaust gas flow control valve, 18 ... Air Flow control valve, 19 …… Coal gasifier, 20 …… Gas refiner, 21
...... Combustor, 3 to 7,8,8 ', 9,11,12,15,15', 17 ...... Piping.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Iwamoto 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitate Manufacturing Co., Ltd.Hitachi Research Laboratory (72) Inventor Yoshio Iwase 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitate Manufacturing Co., Ltd. Hitachi Research Laboratory (72) Inventor Yuichi Kamo 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Institute, Ltd. (72) Inventor Koichi Miyoshi 4026 Kuji Town, Hitachi City, Ibaraki Hitachi Research Laboratory, Ltd. (56) References JP-A-55-148370 (JP, A) JP-A-63-170865 (JP, A)

Claims (1)

[Claims] 1. A molten salt fuel cell power generation system having an anode and a cathode, in which a molten carbonate is used as an electrolyte, carbonate ions are used as a conductor, and a fuel gas is supplied to the anode and an oxidant gas is supplied to the cathode as a reaction gas. When the output of the fuel cell drops below the preset output when the plant is operating with a load connected to the fuel cell in the plant, the fuel gas supplied to the anode of the fuel cell body is the fuel cell body. Means for changing the pressure of the reaction gas by suppressing the supply amount of the fuel gas for a predetermined time so as to be less than the electrochemical equivalent based on the current flowing in the anode, and the surplus of the fuel gas supplied to the anode. Means to bypass the battery body to the combustor, and the excess combustion exhaust gas from the combustor to at least one of the turbine generator and the exhaust heat recovery device. Molten salt fuel cell power plant, characterized in that it comprises means for supplying a.