JPH08153529A - Device and method for replenishing electrolyte of molten carbonate fuel cell - Google Patents

Abstract

PURPOSE: To replenish an electrolyte uniformly into a fuel cell in a short time by decompressing the inside of the cell by means of a decompression suction device when replenishing the electrolyte into the fuel cell, then sucking the electrolyte from an electrolyte supply container, and packing the electrolyte into the cell. CONSTITUTION: As an inert gas is supplied to a cell 16, the cell 16 is heated to 650 deg.C that is a temperature for power-generating operation. Next, fuel gas consisting of 80% H2 and 20% CO2 , and oxidizer gas consisting of 70% air and 30% CO3 are supplied respectively to a fuel gas passage 14a and an oxidizer gas passage 14b by predetermined amounts. The battery voltage during power generation drops gradually. At a predetermined voltage or less after 2000 hours, the electrolyte is judged to have dissipated and then power generation is stopped, and molten carbonate mist is replenished; i.e., the fuel and the oxidizer gas are switched to an inert gas, the gas passage 14a is communicated with a decompression suction device 24, and the electrolyte 21 is sucked from an electrolyte supply container 20 together with the inert gas flowing through a valve 25. The electrolyte 21 passing through the passage 14a is heated and melted within the cell 16, then clings to the gas passage 14a and impregnates the cell, and the sucking is stopped when the temperature of the cell 16 has dropped to a predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolyte replenishing device for a molten carbonate fuel cell using a molten carbonate as an electrolyte and a replenishing method thereof.

[0002]

2. Description of the Related Art Recently, a molten carbonate fuel cell has been developed as a highly efficient energy conversion device. The molten carbonate fuel cell is a method of causing an electrolyte eutectic carbonate consisting of an alkali metal carbonate to a molten state at a melting temperature or higher to cause a cell reaction, and is more expensive than other fuel cells such as a phosphoric acid fuel cell. It has major features such as high power generation efficiency without the need for precious metal catalysts.

In general, a molten carbonate fuel cell is one in which fuel and oxidant gas are supplied to a pair of electrodes sandwiching an electrolyte layer to cause a cell reaction, and the pair of electrodes serves as a gas flow path. It is configured by stacking a plurality of layers with the separator formed.
Then, Li ₂ CO ₃ (lithium carbonate) and K are used as electrolytes.
A eutectic salt with ₂ CO ₃ (potassium carbonate) is used, and the eutectic carbonate is impregnated in the electrolyte matrix.

A unit cell consisting of a pair of electrodes sandwiching an electrolyte matrix and one separator each stacked are called a unit cell. FIG. 5 shows a single cell of a molten carbonate fuel cell and a single cell in which one separator is stacked.

The unit cell 1 is composed of an electrolyte matrix 2 sandwiched between an anode electrode 3 and a cathode electrode 4, and the separator 5 is composed of an interconnector 6 sandwiched between an anode edge plate 7 and a cathode edge plate 8. Separator 5
An anode current collecting plate 9 and a cathode current collecting plate 10 which secure a gas flow path and electrically connect adjacent unit cells to each other are provided therein, and a fuel gas 11 and an oxidant gas 12 are supplied thereto, respectively. When the gas flows in the separator, the fuel gas 11 is oxidant gas 12 on the surface of the anode electrode 3.
Causes a cell reaction on the surface of the cathode electrode 4, and a carbonate ion (CO ₃
^2- ) is exchanged and electric output is obtained outside the battery.

FIG. 5 shows one unit cell 1 and one separator 5
A single cell obtained by stacking the individual cells is shown, but the battery stack is configured by repeatedly stacking the single cells. At this time, the interconnector 6 includes the anode edge plate 7 and the cathode edge plate 8
It is integrated with.

The fuel gas 11 and the oxidant gas 12 supplied to the unit cell 1 are supplied and discharged by separate manifolds provided around the unit cell 1. In FIG. 5, the manifold is an internal manifold type molten carbonate fuel cell in which the manifold 5 is provided inside the separator 5, and the anode edge plate 7 and the cathode edge plate 8 face each other with the unit cell 1 in between.
Are connected by an electrically insulating manifold ring 13.

Next, the electrolyte matrix 2 is one in which carbonate is filled in the interstices of the skeleton having a porous structure composed of metal oxide particles. The carbonate is a solid at room temperature, but becomes a molten state at a temperature of 650 degrees, which is the power generation operating temperature. The anode electrode 3 and the cathode electrode 4 are porous bodies of metal or metal oxide, and the carbonate also partially fills the pore gaps between the anode electrode 3 and the cathode electrode 4.

During operation of this molten carbonate fuel cell,
The fuel gas 11 and the oxidant gas 12 supplied to the anode electrode 3 and the cathode electrode 4, respectively, generate an electrochemical reaction at the interface between the molten carbonate and the anode electrode 3 and the cathode electrode 4 to generate electricity. For stable power generation of such a molten carbonate fuel cell, it is necessary that the anode electrode 3, the cathode electrode 4 and the electrolyte in the electrolyte matrix 2 be constantly maintained in an appropriate amount during power generation.

Usually, this electrolyte is filled in a gas passage for supplying an oxidant or a fuel gas at the time of assembling a fuel cell, or is incorporated in the form of a sheet of eutectic carbonate, so that the electrolyte is not used during the temperature raising process of the fuel cell. It is impregnated into the anode electrode 3, the cathode electrode 4 and the electrolyte matrix 2 at the melting temperature of the crystalline carbonate or higher. The molten carbonate is retained in the electrolyte matrix 2 by its surface tension and the interfacial tension between the skeleton particles of the electrolyte matrix 2 and the molten carbonate. The fuel cell impregnated with the electrolyte is used as the anode electrode 3 at the power generation temperature.
An appropriate amount of electrolyte is distributed in a balanced manner to each of the cathode electrode 4 and the electrolyte matrix 2.

[0011]

However, even if the electrolyte is distributed in an appropriate amount in the early stage of power generation, the electrolyte is carried as vapor by the oxidant gas or the fuel gas and exhausted to the outside of the fuel cell, or the separator is formed. However, there is a problem in that the battery performance is gradually lost and the battery performance deteriorates over time.

Therefore, as a countermeasure against the loss of the electrolyte, as disclosed in, for example, JP-A-62-180966 and JP-A-62-127670,
A method of directly supplying the electrolyte in a molten state from the outside has been proposed. However, in this replenishment method, it is necessary to provide through holes for supplying the electrolyte in the separator and the electrolyte matrix of the fuel cell, which complicates the fuel cell manufacturing process. Further, since the electrolyte supplied from the through-holes is usually supplied while penetrating the electrolyte matrix in the plane direction, it takes a long time to replenish the electrolyte, and there is a drawback that it is not uniformly replenished.

Accordingly, an object of the present invention is to provide an electrolyte replenishing device for a molten carbonate fuel cell and a replenishing method thereof, which can replenish the electrolyte uniformly in the fuel cell in a short time.

[0014]

An electrolyte replenishing device for a molten carbonate fuel cell according to the present invention comprises a fuel gas for an anode electrode of a flat cell formed by sandwiching an electrolyte matrix between an anode electrode and a cathode electrode. The cathode electrode is connected to a gas supply pipe connected to a gas flow path for introducing an oxidant gas, and an electrolyte supply container for storing an electrolyte for replenishing the electrolyte matrix, and an electrolyte supply when replenishing the electrolyte matrix with the electrolyte A gas supply three-way valve for communicating the container with the gas supply pipe, and a decompression suction device for sucking and transporting the electrolyte from the electrolyte supply container into the gas flow passage, which is connected to the gas exhaust pipe connected to the gas flow passage, and the electrolyte. A gas exhaust three-way valve for connecting the vacuum suction device to the gas exhaust pipe when replenishing the matrix with the electrolyte is provided. Then, if necessary, a heater for heating the electrolyte supply container, the gas supply three-way valve, and the gas supply pipe is provided.

Further, the electrolyte supply container for storing the electrolyte is divided into an upper electrolyte supply container and a lower electrolyte supply container,
The upper electrolyte supply container stores an electrolyte for replenishing the electrolyte matrix, and the lower electrolyte supply container is configured to store the electrolyte supplied from the upper electrolyte supply container when replenishing the electrolyte matrix with the electrolyte, A heater for heating the lower electrolyte supply container and the gas supply pipe is provided, and a vacuum suction device for sucking and transporting the electrolyte from the lower electrolyte supply container into the gas flow passage is connected to the gas exhaust pipe connected to the gas flow passage. A gas exhaust three-way valve is provided for connecting the vacuum suction device to the gas exhaust pipe when the electrolyte matrix is replenished with the electrolyte.

If necessary, a porous material filter having an average pore size smaller than the average particle diameter of the electrolyte is provided between the gas exhaust three-way valve and the vacuum suction device, and the gas exhaust three-way valve and the porous filter are provided. An electrolyte reservoir for capturing electrolyte is provided between the body filter and the body filter.

On the other hand, in the present invention, eutectic carbonate is used as the electrolyte in the electrolyte supply container or the lower electrolyte supply container, or a mixed slurry of an organic solvent, an organic binder and a eutectic carbonate is used. ing.

On the other hand, the electrolyte replenishing method for the molten carbonate fuel cell of the present invention is a gas flow in which the molten carbonate fuel cell is unloaded and the fuel gas is introduced to the anode electrode and the oxidant gas is introduced to the cathode electrode. The fuel gas and oxidant gas supplied from the gas supply pipe connected to the passage are switched to the inert gas and supplied to the gas flow path, and the electrolyte supply container storing the electrolyte for replenishment is connected to the gas supply pipe, A decompression suction device for decompressing the flow path is connected to the gas exhaust pipe connected to the gas flow path, and the gas flow path is decompressed by the decompression suction device so that the electrolyte for replenishment from the electrolyte supply container flows into the gas flow path. , Filling the electrolyte and replenishing it.

When the electrolyte in the molten carbonate fuel cell is excessively replenished, the molten carbonate fuel cell is brought into a power generating state after the electrolyte is replenished and replenished, and the anode electrode contains hydrogen as a main component. Fuel gas is supplied, and either air or oxygen is supplied to the cathode electrode to adjust the excessive electrolytic mass in the molten carbonate fuel cell while generating power.

[0020]

[Operation] When replenishing the electrolyte to the electrolytic matrix,
The electrolyte supply container is connected to the gas supply pipe connected to the gas flow passage by the gas supply three-way valve, while the decompression suction device is connected to the gas exhaust pipe connected to the gas flow passage by the gas exhaust three-way valve,
The gas passage is decompressed by the decompression suction device, whereby the electrolyte from the electrolyte supply container is caused to flow into the gas passage for introducing the fuel gas to the anode electrode and the oxidant gas to the cathode electrode.

Normally, the electrolyte is in a molten state when it is introduced into the gas flow path of the unit cell. However, when the electrolyte supply container, the gas supply three-way valve and the heater for heating the gas supply pipe are provided, , Where the electrolyte is in a molten state.

Further, the electrolyte supply container for storing the electrolyte is divided into an upper electrolyte supply container and a lower electrolyte supply container, and the upper electrolyte supply container stores the electrolyte for replenishing the electrolyte matrix, and the lower electrolyte supply container. When the electrolyte is configured to store the electrolyte supplied from the upper electrolyte supply container when the electrolyte is replenished to the electrolyte matrix, the electrolyte is melted in the lower electrolyte supply container by the heater. This molten electrolyte is decompressed in the gas flow path with a vacuum suction device,
The electrolyte from the lower electrolyte supply container is caused to flow into a gas flow path that guides fuel gas to the anode electrode and oxidant gas to the cathode electrode. Then, the porous body filter and the electrolyte reservoir prevent the electrolyte from flowing into the vacuum suction device.

On the other hand, when replenishing the electrolyte, the molten carbonate fuel cell is put into an unloaded state, the fuel gas and the oxidant gas are switched to the inert gas and supplied to the gas flow path, and the replenishing electrolyte is stored. The electrolyte supply container is connected to the gas supply pipe, the decompression suction device for decompressing the gas flow passage is connected to the gas exhaust pipe connected to the gas flow passage, and the gas flow passage is decompressed by the decompression suction device so that the electrolyte supply container The electrolyte for replenishment from the fuel cell is made to flow into the gas flow path to replenish and replenish the electrolyte, and when the replenishment of the electrolyte in the molten carbonate type fuel cell is excessive, after replenishing and replenishing the electrolyte, the molten carbonate type When the fuel cell is in a power generating state, the anode electrode is supplied with a fuel gas containing hydrogen as a main component, and the cathode electrode is supplied with either air or oxygen to generate excess power in the molten carbonate fuel cell while generating power. To adjust the amount of electrolyte.

[0024]

Embodiments of the present invention will be described below. Figure 1
It is a block diagram which shows the 1st Example of this invention. A fuel gas flow path for guiding a fuel gas to the anode electrode 3 of the unit cell is provided in the separator that forms the unit cell by sandwiching the electrolyte matrix 2 between the anode electrode 3 and the cathode electrode 3 and electrically connects adjacent unit cells to each other. 14a and an oxidant gas flow path 14b for guiding the oxidant gas to the cathode electrode 4 are formed. Although FIG. 1 shows the case where there is one unit cell 16 in which one unit cell and one separator are stacked, in practice,
The battery housing 15 is formed by stacking the single cells 16.
The battery housing 15 is housed in a battery housing container 17. Here, the anode electrode is made of a nickel alloy and the cathode electrode 4 is made of nickel. The electrolyte matrix 2 is made of a lithium aluminate holding material.

Next, the fuel gas supply pipe 18a connected to the fuel gas flow passage 14a and the oxidant gas supply pipe 18b connected to the oxidant gas flow passage 14b are connected to the fuel gas supply three-way valve 19a.
Further, the electrolyte supply container 20 is connected via the oxidant gas supply three-way valve 19b. These gas supply three-way valve 19
Is for connecting the electrolyte supply container 20 to each gas supply pipe 18 when the electrolyte matrix 2 is replenished with the electrolyte 21. Further, the upper portion of the electrolyte supply container 20 has a fuel gas supply three-way valve 19a in the fuel gas supply pipe 18a.
Is connected to the upstream side by a pipe, and a valve 25 is provided on the way. This valve 25 is opened when the electrolyte matrix 2 is replenished with the electrolyte 21, and the fuel gas supply pipe 18 is provided.
It is for pushing out the electrolyte 21 to the fuel gas flow path 14a via the fuel gas supply three-way valve 19a by the inert gas from a.

The electrolyte supply container 20 stores an electrolyte 21 for replenishing the electrolytic matrix 2. The electrolyte 21 is a eutectic carbonate of lithium carbonate and potassium carbonate (eutectic temperature 490 ° C.), and is filled with spherical eutectic carbonate fine powder having an average particle size of 1.0 μm. Although not shown in FIG. 1, a desiccant is stored in the electrolyte supply container 20 to prevent the electrolyte 21 from absorbing moisture, and a heater for preventing dew condensation is provided around the electrolyte supply container 20. It is covered.

On the other hand, in the gas exhaust pipe 22a connected to the fuel gas flow passage 14a and the oxidant gas exhaust pipe 22b connected to the oxidant gas flow passage 14b, the electrolyte 21 from the electrolyte supply container 20 and the fuel gas flow passage 14a are oxidized. Agent gas flow path 14
A decompression suction device 24 for sucking and transporting into b is provided via a fuel gas exhaust three-way valve 23a and an oxidant gas exhaust three-way valve 23b. These gas exhaust three-way valves 23 are for connecting the vacuum suction device 24 to the respective gas exhaust pipes 22 when the electrolyte matrix 2 is replenished with the electrolyte 21.

Next, the experiment conducted by the inventors will be described. First, for Experiment 1, with the configuration of the fuel cell shown in FIG. 1, the molten carbonate was lost in the fuel cell,
After that, the conditions and procedures for replenishing the electrolyte 21 from the electrolyte supply container 20 will be described.

The loss of electrolyte in the electrolyte matrix 2 is
The procedure was as follows. First, while supplying the inert gas to the unit cell 16, the unit cell 16 is at the power generation operating temperature of 6
The temperature is raised to 50 ° C., and then the fuel gas flow path 14a is filled with a fuel gas consisting of 80% hydrogen and 20% carbon dioxide gas, and the oxidant gas flow path 14b is filled with an oxidizer containing 70% air and 30% carbon dioxide gas. A predetermined amount of gas was supplied.

After waiting for the cell voltage to stabilize in the open circuit state without taking load output from the fuel cell, the cell was connected to an external load to continue power generation. The battery voltage during power generation tended to gradually decrease with time. About 2
After 000 hours, the battery voltage fell below the predetermined voltage, so it was judged that the electrolyte had been lost, and power generation was interrupted.

Next, replenishment of the molten carbonate mist was carried out as follows. After the fuel cell is in the open circuit state, that is, in the no-load state, the fuel gas and the oxidant gas are switched to the inert gas, and the inside of the single cell 16, the gas supply pipe 18, and the gas exhaust pipe 22 are replaced with the inert gas, The gas supply three-way valve 19 was operated to connect the electrolyte supply container 20 and the gas flow passage 14 in the single cell 16. On the other hand, the gas exhaust three-way valve 23
Was operated to connect the gas passage 14 and the vacuum suction device 24 to each other. Then, after operating the vacuum suction device 24, the valve 2
5, the electrolyte 21 was sucked from the electrolyte supply container 20 together with the inert gas flowing through the valve 25. As a form of the electrolyte 21 in this case, eutectic carbonate on powder or solid was used.

The temperature inside the unit cell 16 remains at 650 ° C. during power generation, and the electrolyte 21 passing through the gas flow path 14 together with the inert gas is heated and melted inside the unit cell 16. The melted electrolyte 21 adheres to the gas flow path 14 and is captured and impregnated into the unit cell. The single cell is cooled by the latent heat of fusion taken by the electrolyte 21, but the suction of the electrolyte 21 is stopped when the temperature of the single cell 16 drops to a predetermined temperature. Carbon dioxide was replenished to the unit cell by this method.

After that, the gas supply three-way valve 19 and the gas exhaust three-way valve 23 are switched to supply the fuel gas and the oxidant gas to the single cell 16. Then, after waiting for the battery voltage to stabilize, if the battery voltage recovered, it was determined that the electrolyte 21 was sufficiently replenished, and the replenishment of the electrolyte 21 was completed. When the battery voltage was not sufficiently recovered, the operation of replenishing the electrolyte 21 was repeated after waiting for the temperature of the unit cell 16 to reach a predetermined temperature. As a result, the battery performance could be restored to 98% of the initial battery performance.

Next, Experiment 2 will be described. Experiment 2 was carried out on the fuel cell having the structure shown in FIG. 1 in which a heater was attached to the gas supply pipe 18 from the electrolyte supply container 20 to the single cell 16 via the gas supply three-way valve 19. That is, the gas supply pipe 18 from the electrolyte supply container 20 to the single cell 16 is heated by a heater to a temperature equal to or higher than the melting point of the electrolyte 21, the electrolyte 21 in the electrolyte supply container 20 is melted, and the electrolyte 21 melted in the single cell 16 is melted. To supply. Therefore, the eutectic carbonate in a molten state is supplied to the single cell.

Power generation was started in the same manner as in Experiment 1, and when the voltage dropped, it was judged that the electrolyte had been lost, and power generation was interrupted. After substituting the gas flow passage 14 in the single cell 16, the gas supply pipe 18, and the gas exhaust pipe 22 with an inert gas, the gas exhaust three-way valve 23 is switched to connect the gas flow passage 14 and the vacuum suction device 24 to each other. After depressurizing the gas flow path 14, the gas supply three-way valve 19 was switched. The electrolyte 21 in the electrolyte supply container 20 was melted, flowed out into the single cell 16, and a predetermined amount of the electrolyte 21 previously charged in the electrolyte supply container 20 was supplied to and impregnated in the unit cell. The electrolyte was replenished to the unit cell by this method.

Thereafter, as in Experiment 1, the fuel gas and the oxidant gas were again supplied to the single cell 16, and when the predetermined cell voltage was obtained, the replenishment of the electrolyte 21 was terminated. When a sufficient battery voltage could not be obtained, the above-mentioned electrolyte 21 replenishing operation was repeated. Also by this method, the battery performance could be restored to 98% of the initial battery performance.

FIG. 2 shows a block diagram of the second embodiment of the present invention. In the second embodiment, the electrolyte supply container 20 for storing the electrolyte 21 is divided into an upper electrolyte supply container 26 and a lower electrolyte supply container 27, and the upper electrolyte supply container 26 has an electrolyte for replenishing the electrolyte matrix 2. 21 is stored in the lower electrolyte supply container 27 and the upper electrolyte supply container 26 is used when the electrolyte matrix 2 is replenished with the electrolyte 21.
It is configured to store the electrolyte 21 supplied from the above, and is provided with a heater 29 for heating the lower electrolyte supply container 27 and the gas supply pipe 18. Other configurations are the same as those shown in FIG.

That is, in the first embodiment shown in FIG. 1, the electrolyte 21 was supplied by switching the gas supply three-way valve 19, but in the second embodiment,
Instead of the gas supply three-way valve 19, an upper electrolyte supply container 26
The valve 28 is connected between the lower electrolyte supply container 27 and the lower electrolyte supply container 27, and the valve 28 is opened to supply the electrolyte 2 in an amount necessary for replenishment.
1 is supplied to the lower electrolyte supply container 27, which is heated by the heater 29 to be in a molten state, and the gas passage 14 of the single cell 16 is supplied.
I am trying to supply it to.

When replenishing the electrolyte 21, the electrolyte 21
Is charged in the upper electrolyte supply container 26, and the pipe from the lower electrolyte container 27 to the single cell 16 is heated to a temperature not lower than the melting point of the electrolyte 21 by the heater 29 for heating. Then, as in Experiment 2 described above, after stopping the power generation and replacing the gas with an inert gas, the gas discharge three-way valve 23 is operated to connect the gas flow path 14 and the decompression suction device 24 to decompression suction. After the gas inside the lower electrolyte supply container 27 and the unit cell 16 is suctioned by operating the container 24, the valves 25 and 28 are opened to move the electrolyte 21 together with the inert gas from the upper electrolyte supply container 26 to the lower electrolyte supply container 27. Send in. The electrolyte 21 is melted in the lower electrolyte container 27, is sent to the single cell 16 in a molten state, and impregnates the single battery. Carbon dioxide was replenished to the unit cell by this method. The repetition when the battery performance is not sufficiently recovered is the same as in the case of Experiment 2 described above.

In the second embodiment, since it is not necessary to provide a valve in the gas supply pipe 18 from the lower electrolyte supply container 27 to the single cell 16, operation of the valve at a temperature above the melting temperature of the electrolyte 21. Does not need Therefore, it is possible to avoid seizure of the valve at high temperature and corrosion of the valve due to the electrolyte 21, so that the reliability of the electrolyte replenishment is improved.

Next, Experiment 3 will be described. Experiment 3 was carried out by filling the electrolyte supply container 20 with a slurry of the electrolyte 21 prepared by the following method for the fuel cell having the configuration shown in FIG. That is, methyl ethyl ketone and polyvinyl butyral were added to the eutectic carbonate powder, and the mixture was stirred and mixed by a ball mill for 24 hours to prepare a slurry of the electrolyte 21. Power generation was started in the same manner as in Experiment 1, and when the battery voltage dropped, it was determined that the electrolyte 21 had been lost, and power generation was interrupted.

The gas exhaust three-way valve 23 was switched to connect the gas flow passage 14 and the decompression suction device 24 to reduce the pressure of the gas flow passage 14, and then the gas supply three-way valve 19 was switched. The slurry in the electrolyte supply container 20 flows out into the single cell 16, where it is heated to the temperature of the single cell 16, and the electrolyte 2
As 1 melts, methyl ethyl ketone and polyvinyl butyral volatilize, and a vacuum suction device together with an inert gas 2
4 is discharged from the inside of the unit cell 16. Carbon dioxide was replenished to the unit cell by this method.

Thereafter, as in Experiment 1, the fuel gas and the oxidant gas were again supplied to the single cell 16, and when the predetermined cell voltage was obtained, the replenishment of the electrolyte 21 was terminated. If a sufficient voltage could not be obtained, the above electrolyte replenishing operation was repeated. Even by this method, the battery performance could be restored to 97% of the initial battery performance.

Regarding the above Experiment 1, Experiment 2 and Experiment 3,
The current per unit area of a single cell is 0.15 A / cm ²
The change in battery voltage when power is generated is shown below. Experiment 1: Initial voltage 0.826V, total replenishment voltage 0.805V, voltage after replenishment 0.825V Experiment 2: Initial voltage 0.815V, total replenishment voltage 0.788V, voltage after replenishment 0.806V Experiment 3: Initial voltage 0.831V, total replenishment voltage 0.802 V, voltage after replenishment 0.815V

As is clear from the results of this experiment, after the battery voltage has dropped, the battery voltage has returned to a value close to the initial voltage by replenishing the electrolyte 21. In each case, it took about 5 minutes to replenish the electrolyte 21, but the replenishment time could be greatly shortened as compared with the conventional method.

In the first and second embodiments described above,
The electrolyte supply container 20 and the vacuum suction device 24 are the battery container 1
Although it is provided outside the battery container 7, it may be provided inside the battery container 17. Further, although the replenishment route of the carbonate as the electrolyte 21 is provided on both the anode side and the cathode side, either one may be provided. Further, as the eutectic carbonate electrolyte to be suction-filled, powder having an average particle size of 1.0 μm was used.
You may use the electrolyte powder selected from the average particle diameter of 0, 1-10 micrometers.

When the electrolyte is used as a slurry, methyl ethyl ketone is used as the organic solvent in the examples, but one selected from ethyl alcohol, propyl alcohol, butyl alcohol, methyl alcohol, methyl isobutyl ketone, ethylene glycol, glycerin and the like. Alternatively, a mixed organic solvent of two or more kinds can be applied. On the other hand, polyvinyl butyral was used as the binder of the electrolyte slurry, but polyvinyl alcohol, polyethylene,
A mixed binder of one kind or two kinds or more selected from carboxymethyl cellulose, polyvinyl acetal and the like can also be applied.

FIG. 3 is a block diagram showing the third embodiment of the present invention. The third embodiment is different from the first embodiment in FIG. 1 in that it is provided between the gas exhaust three-way valve 22 and the decompression suction device 24.
The porous body filter 30 having an average pore diameter smaller than the average particle diameter of the electrolyte 21 is provided. This prevents the carbonate, which is the electrolyte 21, from being sucked into the vacuum suction device 24. This is because when the sucked electrolyte 21 is sucked into the vacuum suction device 24,
The inside of No. 4 is contaminated with the electrolyte 21 and causes not only a malfunction but also the vacuum suction device 24 due to the strongly corrosive carbonate.
This is to prevent it because it may corrode the material.

That is, a porous filter 30 is provided in the middle of the pipe connecting the fuel gas exhaust pipe 22a and the oxidant gas exhaust pipe 22b to the vacuum suction device 24. The porous filter 30 is made of sintered metal having a fine pore diameter. The gas is passed through but the powder or droplets of the electrolyte 21 are not passed through. The electrolyte 21 accumulates in the porous filter 30 with the passage of time and becomes clogged, but at that time, it is replaced with a new one. Further, since the accumulated electrolyte 21 may corrode the material of the porous filter 30, the material of the porous filter 30 is made of nickel metal having excellent corrosion resistance against the electrolyte 21.

In this third embodiment, the electrolyte 21
Since it can be prevented from being captured by the porous filter 30 and being sucked into the vacuum suction device 24, the reliability of electrolyte replenishment can be improved.

FIG. 4 is a block diagram showing the fourth embodiment of the present invention. The fourth embodiment is different from the third embodiment shown in FIG. 3 in that an electrolyte reservoir 3 for capturing the electrolyte 21 is further provided between the gas exhaust three-way valve 23 and the porous body filter 30.
1 is provided. As a result, it is possible to more reliably prevent the carbonate, which is the electrolyte 21, from being sucked into the vacuum suction device 24.

That is, an electrolyte reservoir 31 is provided in front of the porous filter 30 on the way from the fuel gas exhaust pipe 22a and the oxidant gas exhaust pipe 22b to the vacuum suction device 24. The gas passing through the inside of the battery is sucked from the side of the electrolyte reservoir 31, collides with the baffle plate 32 inside the electrolyte reservoir 31, changes the flow direction, and further collides with the baffle plate 33. The powder or mist of the electrolyte 21 contained in the gas is separated from the inert gas by the two collisions. Excess electrolyte 21 is trapped in this electrolyte reservoir 31,
Adhesion to the porous filter 30 can be prevented. Therefore, it is possible to suppress the clogging of the porous filter 30 due to the carbonate as the electrolyte 21, and it is possible to stably operate the decompression suction device 24 for a long period of time.

Next, the treatment of the excessively replenished electrolyte 21 will be described. Fuel cell 1 according to the embodiment described above
When the electrolyte 21 is replenished in the inside of 6, the predetermined amount of the electrolyte 21 is supplied to the electrolyte supply container 20, but it is difficult to accurately grasp the amount. The required amount in the battery is only estimated from the performance, and the electrolyte supply container 20
It is not possible to specify the amount of the electrolyte 21 that adheres in the path leading to the fuel cell or the amount of the electrolyte 21 that passes through or is discharged without remaining in the cell. Therefore, the electrolyte 21 supplies an approximate amount, but in some cases, the electrolyte 21 may be excessively supplied to the fuel cell. With excessive electrolyte, the desired battery performance is not obtained.

Therefore, in such a case, the excess electrolyte is removed by the following method. That is, power generation operation is performed without including carbon dioxide in the oxidant gas. Here, in normal power generation operation, the same amount of oxygen and carbon dioxide gas in the oxidant gas are converted into carbonate ions on the cathode electrode, move in the electrolyte matrix and move in the fuel gas on the anode electrode. Reacts with hydrogen. When power is generated without including carbon dioxide in the oxidant gas, the carbonate ions of the carbonate react with hydrogen, and the carbonate is consumed.

That is, when the amount of the replenished electrolyte is more than the required amount, the fuel gas containing hydrogen as a main component is supplied to the anode electrode and the air or oxygen is supplied to the cathode electrode after the battery is in a power generating state. Is supplied and the load is maintained for a certain period of time. By this operation, excess electrolyte can be consumed on the anode electrode side by the next cell reaction. ^{_{Anode: H 2 + CO 3 2- →}} H 2 O + CO 2 + 2e - ^{_{cathode: O 2 + 4e - → 2O}} 2- As a result, consume excess electrolyte 21, it is possible to supply an appropriate amount of the electrolyte 21, The reliability of electrolyte replenishment is improved.

[0056]

As described above, according to the present invention, when the electrolyte mass in the molten carbonate fuel cell becomes insufficient, the electrolyte can be uniformly replenished in the cell in a short time. Excess electrolyte can be easily removed if over-supplemented.

That is, in the present invention, when the electrolyte is replenished into the fuel cell, the inside of the cell is decompressed by the vacuum suction device and the electrolyte is sucked from the electrolyte supply container to fill the inside of the cell. Can be introduced into the battery.

Further, by providing a porous filter in the middle of the pipe connecting the fuel cell to the vacuum suction device, it is possible to prevent the excessively sucked electrolyte from being sucked into the vacuum suction device. . Further, by providing the electrolyte reservoir in front of the porous filter, it is possible to prevent the electrolyte from clogging the porous filter, and the excess electrolyte can be reused.

When the electrolyte is excessively replenished in the battery, the replenishment amount can be easily adjusted by consuming carbonate ions in the power generation state.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 5 is an exploded perspective view showing a single cell of a molten carbonate fuel cell and a single cell in which one separator is stacked.

[Explanation of symbols]

 1 Single Cell 2 Electrolyte Matrix 3 Anode Electrode 4 Cathode Electrode 5 Separator 6 Interconnector 7 Anode Edge Plate 8 Cathode Edge Plate 9 Anode Current Collector Plate 10 Cathode Current Collector Plate 11 Fuel Gas 12 Oxidizer Gas 13 Manifold Ring 14 Gas Flow Path 15 Housing 16 Single cell 17 Battery storage 18 Gas supply pipe 19 Gas supply three-way valve 20 Electrolyte supply container 21 Electrolyte 22 Gas exhaust pipe 23 Gas exhaust three-way valve 24 Decompression suction device 25, 28 Valve 26 Upper electrolyte supply container 27 Lower electrolyte supply container 29 Heater 30 Porous filter 31 Electrolyte reservoir 32, 33 Baffle plate

Claims (9)

[Claims] 1. A flat cell formed by sandwiching an electrolyte matrix between an anode electrode and a cathode electrode, and a gas flow for introducing a fuel gas to the anode electrode of the cell and an oxidant gas to the cathode electrode. Molten carbonate fuel for replenishing electrolyte to the electrolyte matrix from the gas flow path of the fuel cell stack in which the separators that alternately form the channels and electrically connect the adjacent unit cells are alternately stacked. In an electrolyte replenishing device for a battery, an electrolyte supply container connected to a gas supply pipe connected to the gas flow path to store an electrolyte for replenishing the electrolyte matrix, and the electrolyte supply when replenishing the electrolyte matrix with the electrolyte. A gas supply three-way valve for communicating the container with the gas supply pipe and a gas exhaust pipe connected to the gas flow path. A vacuum suction device for sucking and transporting the electrolyte from the electrolyte supply container into the gas flow path, and a gas for communicating the vacuum suction device with the gas exhaust pipe when replenishing the electrolyte matrix with the electrolyte. An electrolyte replenishing device for a molten carbonate fuel cell, comprising an exhaust three-way valve. 2. The electrolyte replenishing device for a molten carbonate fuel cell according to claim 1, further comprising a heater for heating the electrolyte supply container, the gas supply three-way valve, and the gas supply pipe. . 3. A flat cell formed by sandwiching an electrolyte matrix between an anode electrode and a cathode electrode, and a gas flow for introducing a fuel gas to the anode electrode of the cell and an oxidant gas to the cathode electrode. Molten carbonate fuel for replenishing electrolyte to the electrolyte matrix from the gas flow path of the fuel cell stack in which the separators that alternately form the channels and electrically connect the adjacent unit cells are alternately stacked. In an electrolyte replenishing device for a battery, an upper electrolyte supply container that stores an electrolyte for replenishing the electrolytic matrix, and the upper portion when replenishing the electrolyte matrix with the electrolyte connected to a gas supply pipe connected to the gas flow path. A lower electrolyte supply container for storing the electrolyte supplied from the electrolyte supply container, and the lower electrolyte supply container And a heater for heating the gas supply pipe, and a vacuum suction device for sucking and transporting the electrolyte from the lower electrolyte supply container connected to the gas exhaust pipe connected to the gas flow passage into the gas flow passage, An electrolyte replenishing device for a molten carbonate fuel cell, comprising: a gas exhaust three-way valve for connecting the decompression suction device to the gas exhaust pipe when replenishing the electrolyte matrix with the electrolyte. 4. A porous filter having an average pore size smaller than the average particle size of the electrolyte is provided between the gas exhaust three-way valve and the vacuum suction device. An electrolyte replenishing device for a molten carbonate fuel cell according to item 1. 5. An electrolyte replenishing device for a molten carbonate fuel cell according to claim 4, wherein an electrolyte reservoir for capturing an electrolyte is provided between the gas exhaust three-way valve and the porous body filter. . 6. An electrolyte replenishment for a molten carbonate fuel cell according to claim 1, wherein a eutectic carbonate is used as an electrolyte in the electrolyte supply container or the lower electrolyte supply container. apparatus. 7. The mixed slurry of an organic solvent, an organic binder and a eutectic carbonate is used as an electrolyte in the electrolyte supply container or the lower electrolyte supply container. An electrolyte replenishing device for a molten carbonate fuel cell according to item 1. 8. A gas flow path for introducing a fuel gas to the anode electrode and a gas passage to introduce an oxidant gas to the anode electrode of a flat plate-shaped cell formed by sandwiching an electrolyte matrix between the anode electrode and the cathode electrode. An electrolyte of a molten carbonate fuel cell for replenishing electrolyte to the electrolyte matrix from the gas flow path of the fuel cell stack, which is alternately laminated with separators electrically connecting the adjacent unit cells together. In the replenishment method, the molten carbonate fuel cell is put into an unloaded state, and the fuel gas and the oxidant gas supplied from the gas supply pipe connected to the gas flow path are switched to an inert gas to the gas flow path. An electrolyte supply container that supplies and stores an electrolyte for replenishment is connected to the gas supply pipe, and a decompression suction device for decompressing the gas flow path is provided. It is connected to a gas exhaust pipe connected to a gas flow path, the gas flow path is decompressed by the decompression suction device, and an electrolyte for replenishment from the electrolyte supply container is caused to flow into the gas flow path to replenish and replenish the electrolyte. An electrolyte replenishing method for a molten carbonate fuel cell, which is characterized by the above. 9. When the electrolyte in the molten carbonate fuel cell is excessively replenished, the molten carbonate fuel cell is brought into a power generation state after filling and replenishing the electrolyte, and hydrogen is supplied to the anode electrode. A fuel gas as a main component is supplied, and either air or oxygen is supplied to the cathode electrode,
The electrolyte replenishment method for a molten carbonate fuel cell according to claim 10, wherein an excessive electrolytic mass in the molten carbonate fuel cell is adjusted while generating power.