JPH08153528A - Molten carbonate fuel cell - Google Patents

Abstract

PURPOSE: To enable carbonate to be replenished into a cell in a short time by supplying carbonate mist produced by a molten carbonate mist generator into the gas passage of a separator, and causing the mist to be captured by a current collector plate and a collector. CONSTITUTION: A molten carbonate mist feeder 40 for feeding molten carbonate mist to a fuel gas passage 19 is provided; i.e., the feeder 40 has a molten carbonate mist generator 18 in a fuel gas supply manifold 42. The generator 18 produces a mist of molten carbonate in a gas phase, and the mist is allowed to pass through the manifold on the flow of fuel gas 11, fed to the fuel gas passage 19 within a separator, and captured mainly by an anode current collector plate located within the passage 19, and fine droplets of the molten carbonate mist are flocculated and absorbed by an anode 3.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In general, a fuel cell is a device for directly converting an electrochemical reaction occurring on an electrode into an electric output, and in order to perform this electrochemical reaction, a pair of electrodes facing each other with an electrolyte matrix interposed therebetween is used. The fuel gas and the oxidant gas are continuously supplied. That is, a plate-shaped unit cell in which an electrolyte matrix is sandwiched between both electrodes and a separator that separates a fuel gas and an oxidant gas and forms a gas flow path that leads to a pair of both electrodes are alternately laminated to form a fuel cell. Is configured.

A fuel cell using a eutectic salt of lithium carbonate and potassium carbonate as an electrolyte is called a molten carbonate fuel cell, and a single cell of the molten carbonate fuel cell is impregnated with this eutectic carbonate. It Further, the electrolyte matrix has a porous structure composed of metal oxide particles. Carbon dioxide, which is a eutectic salt of lithium carbonate and potassium carbonate, is filled in the gaps in the skeleton of the porous structure. This carbonate is solid at room temperature, but becomes molten at the power generation operating temperature of 650 ° C. That is, the carbonate is retained in the skeleton of the porous structure due to the surface tension of the liquid carbonate and the interfacial tension between the skeleton particles and the liquid carbonate.

On the other hand, the anode electrode and the cathode electrode are porous bodies of metal or metal oxide, and the carbonate also fills a part of the pores between the anode electrode and the cathode electrode. Then, during the power generation operation, the fuel gas and the oxidant gas respectively supplied to the anode electrode and the cathode electrode cause an electrochemical reaction with the molten carbonate at the interface between the anode electrode and the cathode electrode to generate power. That is, the fuel gas is on the surface of the anode electrode,
The oxidant gas causes a cell reaction on the surface of the cathode electrode, and carbonate ions are exchanged between the electrodes via the carbonate to obtain an electric output to the outside.

A stack of a single battery and one separator is called a single cell. FIG. 8 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 and an anode electrode 3 and a cathode electrode 4 which are arranged in close contact with both surfaces of the electrolyte matrix 2. Further, the separator 5 is basically
It comprises an interconnector 6, an anode edge plate 7, and a cathode edge plate 8. The anode edge plate 7 houses an anode current collector plate 9, and the cathode edge plate 8 houses a cathode current collector plate 10. Therefore, the anode current collector 9
The cathode current collector plate 10 is also a component of the separator 5. The interconnector 6 is the anode edge plate 7
Also, the cathode edge plate 8 and the peripheral portion are joined to form an integral structure. Therefore, the anode current collector plate 9 and the cathode current collector plate 10 also face each other with the interconnector 6 interposed therebetween.

Next, a manifold for gas supply and discharge is provided around the electrochemical reaction portion of the unit cell 1. FIG. 8 shows an internal manifold type in which the manifold is provided inside the separator 5, and the anode edge plate 7 and the cathode edge plate 8 facing each other with the unit cell 1 sandwiched therebetween are connected by an electrically insulating manifold ring 13. To be done. The fuel cell stack is configured by repeatedly stacking a plurality of such single cells.

Further, as shown in FIG. 9, the anode current collecting plate 9 has an anode current collecting portion 9a for supporting the electrode surface of the anode electrode 3 and a fuel gas 11 provided so as to project from the anode current collecting portion 9a. And an anode current collector support 9b for supporting the anode current collector 9a. Similarly, the cathode current collector 10 also has the cathode electrode 4
Collector part 10a for supporting the electrode surface of the cathode collector part, and a cathode collector part support for supporting the cathode collector part 10a while forming a flow path for the oxidant gas 12 provided so as to project from the cathode collector part 10a. And 10b.

The anode current collector 9a and the anode current collector support 9b, or the cathode current collector 10a and the cathode current collector support 10b are independent elements, as shown in FIG. It may be configured. In either case, the fuel gas 11 and the oxidant gas 12
Is an anode current collector support 9b inside the separator 5.
And the cathode current collector support 10b.

The molten carbonate fuel cell thus constructed is generally targeted for a life of 40,000 hours for the time being. Therefore, it is necessary that the electrolyte carbonate is stably retained in the electrolyte matrix for a long period of time.

[0010]

However, the carbonate impregnated in the electrolyte matrix is lost due to the following three main reasons. First, since the molten carbonate is in a liquid state during the power generation operation, it will flow out to the surface of the separator or the like over time due to changes in the microstructure of both electrodes and the electrolyte matrix. Second, molten carbonate is highly corrosive, corrodes metallic separator materials, and is consumed by the corrosion.
Thirdly, carbonate is volatilized in the fuel gas or the oxidant gas and is discharged together with these gases.

In order to prevent the loss of carbonate due to these reasons, the development of an electrolyte matrix excellent in carbonate retention, the development of a separator material which is not easily corroded by carbonate,
Alternatively, development of an operation technique that suppresses the local temperature rise of the unit cell to prevent the volatilization of carbonate is being carried out.

The loss of carbonate is first preceded by the electrode having a larger pore size than the skeleton of the electrolyte matrix. The lack of carbonate in the electrodes increases the internal resistance of the battery. That is, the three-phase interface where carbonate and gas coexist on the electrode surface, that is, the surface area that causes a battery reaction is reduced, and the internal resistance of the battery is increased. Further, when the loss of the carbonate progresses and the amount of the carbonate in the electrolyte matrix becomes insufficient, pores are generated in the electrolyte matrix and the internal resistance of the battery increases. Further, the fuel gas and the oxidant gas are directly mixed and burned, and not only the gas is wastefully lost, but also the temperature rise due to the combustion accelerates the deterioration of the electrolyte matrix.

Therefore, apart from the development of the carbonate loss control, attempts have been made to replenish the lost amount of carbonate. For example, in Japanese Examined Patent Publication No. 6-22147, after the carbonate is lost, the battery temperature is lowered to a temperature just above the condensation temperature of the carbonate, and the carbonate vapor is supplied to a fuel gas or oxidant gas supply channel. A method is proposed in which the supersaturated vapor is condensed by supplying it into the battery.

However, in order to replenish the carbonate by this method, it takes a time corresponding to the power generation time taken until the carbonate is lost, or a longer time than that. That is, if it is assumed that the carbonate of saturated vapor pressure is volatilized in the gas, the temperature of the steam generator is 650 degrees, which is about the operating temperature of the molten carbonate fuel cell, and therefore volatilized in the cell. It takes as much time as it takes to volatilize and lose even if you replenish only a minute of carbonate.

Therefore, an object of the present invention is to provide a molten carbonate fuel cell capable of supplying carbonate to the cell in a short time.

[0016]

The molten carbonate fuel cell of the present invention comprises a plate-shaped unit cell having an electrolytic matrix sandwiched between an anode electrode and a cathode electrode, and a fuel gas flow to the anode electrode of the unit cell. A fuel cell stack through which a fuel gas is introduced into the cathode electrode, and a separator which guides the oxidant gas to the cathode electrode by separating the oxidant gas through an oxidant gas flow path, and a fuel cell stack in which the fuel gas is introduced into the fuel gas flow path. Fuel gas supply pipe for supplying, oxidant gas supply pipe for supplying oxidant gas to the oxidant gas flow path, separator provided in at least one of the fuel gas supply pipe and the oxidant gas supply pipe And a molten carbonate mist supply device for supplying the molten carbonate mist to at least one of the fuel gas passage and the oxidant gas passage.

The molten carbonate mist supply device includes a carbonate reservoir for storing the molten carbonate to be supplied, a gas heater for storing a carrier gas for carrying the molten carbonate, and a molten carbonate reservoir. It is composed of a venturi-type mist generating device for dispersing molten carbonate in the form of mist and supplying the carrier gas from the gas heater to the fuel gas passage or the oxidant gas passage.

The venturi-type mist generating device in this case is a nozzle to which a carrier gas carrying molten carbonate mist is supplied, a venturi having a throat portion provided at the outlet of the nozzle and having a narrowed flow passage cross section, and a throat. And a molten carbonate supply port to which molten carbonate is supplied.

On the other hand, in the invention of claim 4, the molten carbonate mist supply device disperses the carbonate reservoir for storing the molten carbonate to be supplied and the molten carbonate from the molten carbonate reservoir in a mist form. And a jet ejector type mist generating device for supplying to the fuel gas flow path or the oxidant gas flow path.

The jet ejector type mist generating device in this case comprises a nozzle for injecting the molten carbonate supplied from the carbonate reservoir, and a spiral blade provided in the nozzle for giving a rotating flow to the molten carbonate. An injection port for injecting the molten carbonate, which is given a rotating flow by the spiral blade, in a mist form.

Further, a mist collector for changing the flow direction of the molten carbonate mist is provided in the fuel gas passage or the oxidant gas passage inside the separator. This mist collector is composed of a plurality of baffle plates, and is integrally provided on the anode current collector plate and the cathode current collector plate provided in the separator adjacent to the anode electrode and the cathode electrode.

[0022]

The molten carbonate mist produced by the carbonate mist producing device is carried to the gas flow path in the separator together with the gas flow, and adheres to and is captured by the current collector plate or the mist collector. The captured molten carbonate is absorbed by the anode electrode or the cathode electrode and impregnated into the unit cell. As a result, the carbonate is replenished to the single cell from which the carbonate has been lost.

Particularly, in the venturi type mist generating device and the jet ejector type mist generating device, since carbonate mist having a high concentration in the gas phase is purified, it is possible to easily replenish the unit cell with the carbonate.

Further, if a mist collector is provided in the gas passage in the separator, the mist collector effectively captures the carbonate mist, and the amount of carbonate mist discharged through the separator is greatly increased. Less.

[0025]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a molten carbonate fuel cell of the present invention. The fuel cell stack is configured by alternately stacking a plurality of unit cells and separators, but in FIG. 1, in order to simplify the description, a case where one unit cell 1, that is, one cell 14 is used. Shows.

The unit cell 1 is formed in a plate shape with the electrolytic matrix 2 sandwiched between the anode electrode 3 and the cathode electrode 4. A fuel gas passage 19 formed in the separator is located on the anode electrode 3 side of the unit cell 1, and an oxidant gas passage 2 formed in the separator is formed on the cathode electrode 4 side.
0 is located.

The fuel gas 11 is supplied to the fuel gas passage 19 of the cell 14 through the fuel gas supply pipe 42 and is guided to the anode 3 electrode of the unit cell 1. Then, the fuel gas scrubber 15 is passed and discharged. Similarly, cell 1
4, the oxidant gas supply pipe 43
The oxidant gas 12 is supplied to the cathode electrode 4 of the unit cell 1 through the gas. And oxidizer gas scrubber 1
Pass 6 and discharge. Usually, a part of the oxidant gas discharged from the cell 14 is returned to the upstream of the cell 14 by the recycle blower 17 to reuse the active ingredient. The fuel gas scrubber 15 and the oxidant gas scrubber 1
6 captures and removes the carbonate contained in the gas.

In the embodiment of the present invention shown in FIG. 1, a molten carbonate mist supply device 40 for supplying the molten carbonate mist to the fuel gas passage 19 is provided. That is, the molten carbonate mist supply device 40 has the molten carbonate mist generation device 18 in the middle of the fuel gas supply pipe 42. The molten carbonate mist generator 18 generates mist of molten carbonate in the gas phase, and the molten carbonate mist passes through the manifold as the fuel gas 11 flows and passes through the fuel gas passage in the separator. It is carried to 19 and mainly fuel gas flow path 1
The fine droplets of the molten carbonate mist are collected by the anode current collector plate 9 and aggregated and absorbed by the anode electrode 3.

As described above, in the embodiment of the present invention shown in FIG. 1, the molten carbonate mist generator 18 is provided in the middle of the fuel gas supply pipe 42, but it may be provided in the oxidant gas supply pipe 43. . Also in this case, similarly, the molten carbonate mist passes through the manifold along with the flow of the oxidant gas 12 and is conveyed to the oxidant gas flow passage 20 in the separator, and mainly the cathode collector in the oxidant gas flow passage 20. The fine droplets of the molten carbonate mist are captured by the electric plate and aggregated and absorbed by the cathode electrode 4.

Next, the experiments conducted by the inventors will be described. First, the conditions and procedures when the molten carbonate mist is lost in the fuel cell and then the molten carbonate mist generator 18 is replenished with the molten carbonate mist will be described.

Loss of molten carbonate was carried out as follows. The cell 14 was heated up to about 650 ° C. which is the operating temperature of the fuel cell in an atmosphere of nitrogen gas which is an inert gas. After that, hydrogen 8 is added to the fuel gas flow path 19 on the anode side.
Fuel gas consisting of 0% and carbon dioxide gas 20%, air 70% and carbon dioxide gas 30% in the oxidant gas flow path 20 on the cathode side.
A predetermined amount of oxidant gas consisting of was supplied. Then, the battery was connected to an external load to generate power. Then, the battery voltage during power generation tended to gradually decrease with time, and when the battery voltage fell below a predetermined voltage, it was determined that carbonate had been lost, and power generation was stopped.

Next, the molten carbonate mist was replenished as follows. With the fuel cell open, fuel gas 1
1 and the oxidant gas 12 are switched to nitrogen gas, and the gas in the fuel gas passage 19 and the oxidant gas 20 in the cell 14 is replaced with nitrogen gas which is an inert gas, and then the carbonate mist generator 18 is set. When activated, a carbonate mist was produced in the nitrogen gas on the fuel gas side. The temperature inside the cell 14 remains at about 650 degrees at the time of power generation, and the carbonate mist passing through the fuel gas flow path 19 together with the nitrogen gas is impregnated into the unit cell. A part of the carbonate mist passed through the cell 14 and was collected by the fuel gas scrubber 15. Carbon dioxide was replenished to the unit cell by such a procedure.

After that, the fuel gas 11 and the oxidant gas 12 were supplied again to the cell 14 instead of the nitrogen gas, and after waiting for the voltage to stabilize, the power generation was restarted. By this carbonate supplement, the battery performance could be restored to 98% of the initial battery performance.

FIG. 2 shows a carbonate mist generator 1 of the present invention.
9 shows a Venturi type mist generator 21 used as No. 8. This Venturi type mist generator 2
No. 1 is for making a molten carbonate mist by a high-speed flow of gas, and a high-concentration molten carbonate mist can be obtained. That is, the venturi-type mist generator 21 includes a nozzle 23 that supplies a carrier gas 22 that carries molten carbonate mist into the battery, and a venturi 24 that has a throat portion with a narrowed flow passage cross section at the nozzle outlet. Prepare,
The float portion is provided with a carbonate supply port 25 for supplying the molten carbonate. Nitrogen gas, which is an inert gas, is used as the carrier gas 22 and is heated in advance to the melting temperature of the carbonate or higher. The venturi-type mist generator 21 is also kept at a temperature higher than the melting temperature of the carbonate by a heater.

The carrier gas 22 is squeezed by the venturi 24 to become a high-speed flow, and the molten carbonate supplied from the carbonate supply port 25 is dispersed on the mist. The molten carbonate mist is carried into the battery by the carrier gas 22 and captured by the current collector plate or the like. Then, by impregnating the single cell, the carbonate is supplied to the cell.
Since a high concentration molten carbonate mist is obtained in this Venturi type mist generator 21, the carbonate can be replenished in a shorter time. Further, since the Venturi-type mist generator 21 causes the molten carbonate to accompany the high-speed flow of the carrier gas 22, the driving force such as a pump is not required to supply the carbonate. Therefore, the carbonate, which is highly corrosive to metals, is not exposed to the driving device having a complicated mechanism portion such as a pump, so that the reliability can be improved.

FIG. 3 shows a Venturi type mist generator 2.
1 is a configuration example showing an embodiment of the present invention in which No. 1 is incorporated in a fuel gas supply pipe 42 of a fuel cell. That is, in this embodiment, the molten carbonate mist supply device 40 includes a carbonate reservoir 29 for storing the molten carbonate to be supplied, a gas heater 31 for heating a carrier gas for carrying the molten carbonate, and a melting device. And a venturi-type mist generation device 21 for dispersing the molten carbonate from the carbonate reservoir 29 into a mist and supplying the carrier gas 22 from the gas heater 31 to the fuel gas passage 19.

The fuel cell stack 26 is constructed by alternately stacking a plurality of unit cells 1 and separators 5 shown in FIG. The fuel cell stack 26 is tightened from above and below by a tightening device 27 and installed in a container 28. The venturi-type mist generator 21 is arranged in the fuel gas supply pipe 24, and the carbonate contained in the carbonate reservoir 29 is supplied to the venturi-type mist generator 21 from the carbonate supply port 25 at the throat of the venturi 24. Sent. The inside of the carbonate reservoir 29 is pressurized by nitrogen gas, and the molten carbonate is pushed out through the carbonate supply port 25 at high pressure. In this case, the pipes to the carbonate reservoir 29 and the Venturi-type mist generating device 21 are kept at a temperature equal to or higher than the melting temperature of carbonate by the electric heater 30.

On the other hand, the carrier gas 22 becomes a high-speed flow at the throat part of the venturi-type mist generator 21 through the gas heater 31 provided with an electric heater in the gas flow path,
The carbonate is ejected from the nozzle together with the carbonate extruded at a high pressure from the carbonate supply port 25. At this time, the carrier gas 22 is supplied to the gas heater 31 by the blower, and the gas heater 31 causes the operating temperature of the fuel cell to be about 650 ° C.
To be heated. The pipes to the gas heater 31 and the venturi-type mist generator 21 are insulated from the outside air by a heat insulating material.

In this way, the carbonate mist dispersed by the carrier gas 22 is sent to the fuel gas supply manifold by the gas flow of the carrier gas 22, and sent from the manifold to the gas passage of each single cell. When the carbonate mist is supplied to the fuel gas side, nitrogen gas is supplied to the oxidant gas side so that the pressure difference between the both sides of the unit cell does not become large. Further, the carbonate adhering to the manifold or the like aggregates and flows down, and is stored in the carbonate recovery container 32. In the above description, the venturi-type mist generation device 21 is shown as being incorporated in the fuel gas supply pipe 42 of the fuel cell, but it may be incorporated in the oxidant gas supply pipe 43.

Next, FIG. 4 shows the construction of a jet ejector type mist generator 33 used as the carbonate mist generator 18 of the present invention. The jet ejector type mist generating device 33 disperses the molten carbonate sprayed from the nozzle in the gas phase to form a mist, and like the venturi type mist generating device 21, a high-concentration mist can be obtained. The jet ejector type mist generating device 33 is provided with a nozzle 35 having a fine injection port 34, and the nozzle 35 is provided with a spiral blade 36 near the outlet of the nozzle 35 for giving a rotating flow to the molten carbonate to be injected.
The molten carbonate given the rotating flow by the spiral blade 36 is squeezed at the nozzle outlet and spouts from the jet port at high speed. FIG. 4 shows the state of the carbonate 37 spouted.

Here, the jet ejector type mist generator 33 is provided in the fuel gas supply pipe 42 or the oxidant gas supply pipe 43. In this case, fuel gas 1
The molten carbonate mist will be directly injected into 1 or into the oxidizing gas 12. That is, the molten carbonate mist is carried into the battery together with the gas in the gas phase, that is, the fuel gas 11 or the oxidant gas, is captured by the current collector plate and the like and is impregnated in the unit cell to supply the carbonate to the cell.

In this case, the fuel gas 11 or the oxidant gas 12 keeps the entire nozzle 35 at a temperature above the melting temperature of carbonate. Since the jet ejector type mist generator 33 can also obtain a high-concentration mist, the carbonate can be replenished in a shorter time. Further, since the jet ejector type mist generator 33 can directly inject the fuel gas or the oxidant gas, it is possible to replenish the carbonate during the power generation operation of the fuel cell.

FIG. 5 is a constitutional view showing an embodiment of the present invention in which the jet ejector type mist generating device 33 is incorporated in the fuel gas supply pipe 42 of the fuel cell. In this embodiment, the molten carbonate mist supply device 40 includes a carbonate reservoir 29 for storing the molten carbonate to be supplied and a molten carbonate from the molten carbonate reservoir 29 dispersed in a mist form to form a fuel gas flow path. And a jet ejector type mist generator 33 for supplying the mist.

The fuel cell stack 26 is constructed by alternately stacking a plurality of unit cells 1 and separators 5. The fuel cell stack 26 is tightened from above and below by a tightening device 27 and installed in a container 28. Then, the jet ejector type mist generating device 33 is arranged in the fuel gas supply pipe 42, and the carbonate contained in the carbonate reservoir 29 is pushed out from the injection port. The inside of the carbonate reservoir 29 is pressurized by nitrogen gas, and is maintained at a high pressure during the carbonate injection. In this case, the pipes to the carbonate reservoir 29 and the jet ejector type mist generating device 33 are kept at a temperature higher than the melting temperature of carbonate by the electric heater 30.

In this way, the carbonate mist dispersed in the fuel gas 11 is sent to the fuel gas supply manifold together with the fuel gas 11, and sent from the manifold to the gas passage of each single cell. Carbonate adhering to the manifold or the like aggregates and flows down, and is stored in the carbonate recovery container 32. In the above description, the venturi-type mist generation device 2 is used.
Although the fuel cell No. 1 is incorporated in the fuel gas supply pipe 42 of the fuel cell, the fuel cell No. 1 may be incorporated in the oxidant gas supply pipe 43.

Next, a mist collector for effectively trapping the molten carbonate mist sent into the fuel cell will be described. The anode current collector plate 9 and the cathode current collector plate 10 are configured so as not to resist the flow of the fuel gas 11 and the oxidant gas 12, as illustrated in FIG. Therefore,
The molten carbonate mist may adhere to the anode current collector plate 9 or the cathode current collector plate 10, or may be discharged without adhering. In this case, mainly due to the gravity of the molten carbonate mist, the trapping effect that adheres to the bottom surface of the gas flow path in the fuel cell is expected. In this case, if the gas flow velocity is high, the flow path length is short, or the molten carbonate mist diameter is small, the trapping efficiency becomes poor.

Therefore, in the present invention, in order to effectively capture the molten carbonate mist, an inertial force type mist collector is provided in the gas passage in the battery. This mist collector is provided with a plurality of baffles that block the flow direction of gas, and uses the inertial force of the molten carbonate mist to attach the mists to the baffles and collect them. An embodiment of an inertial force type mist collector is shown in FIG. In FIG. 6, a baffle plate 39 is provided as the mist collector 38. The baffles 39 are arranged in a staggered arrangement as shown in FIG. 6 over the entire width of the gas flow path. The gas containing the molten carbonate mist flows as shown by the arrow in FIG. 6, and the molten carbonate mist collides with the baffle plate 39 each time it passes through each row of the baffle plates 39. That is, when the gas flow direction changes, the carbonate mist that attempts to go straight by the inertial force collides with the baffle plate. The inertial force type mist collector 38 having such a structure can effectively capture the carbonate mist.

The carbonates captured by the baffle plate 39 gradually aggregate and flow down due to gravity. Alternatively, it is absorbed by the electrode due to the capillary action of the electrode. As a result, carbonate can be replenished to the unit cell. By providing such an inertial force type mist collector at one place or a plurality of places in the flow direction of the gas flow path, the carbonate mist can be collected more effectively, and the carbon dioxide discharged in vain. The amount of salt mist can be significantly reduced.

Here, when such an inertial force type mist collector 38 is partially provided in the gas flow path, the carbonate is preferentially replenished in that portion, so that the entire surface of the unit cell is uniformly replenished. If you want to do so, there are cases where it is not preferable. Therefore, FIG.
As shown in, the mist collector 38 may be provided integrally with the anode current collector 9 or the cathode current collector 10 provided in the separator. That is, the baffle plates 39 in each row shown in FIG. 6 are configured by the projections 41 on the anode current collector plate 9 or the cathode current collector plate 10 and the intervals thereof are widened. As a result, the collision efficiency of the carbonate mist is lowered, and it becomes possible to more uniformly replenish the entire cell with the carbonate.

When the gas is made to flow in the direction shown by the arrow in FIG. 7,
The gas sewes between the protrusions 41 and flows, but at that time, the flow direction is changed, so that the carbonate mist adheres to the protrusions 41 by its inertial force. As the anode current collector plate 9 or the cathode current collector plate 10, the lower surface in FIG. 7 is arranged on the electrode side, and the upper surface is arranged on the interconnector side. Therefore, while supporting the electrode surface, the projection 41 serves as a current path. It will work. In the current collectors 9 and 10 as described above, the carbonate mist can be captured by each projection 41, and the carbonate can be evenly collected over the entire current collector. As a result, the carbonate can be evenly supplied to the entire unit cell.

Since the inertial force type mist collector 38 is provided in the gas flow path, the pressure loss of the gas is increased. Therefore, the pressure loss is increased not only when the carbonate is replenished but also during the power generation of the battery. Become. As shown in FIG. 1, the oxidant gas 12 is circulated by the recycle blower 17, whereas the fuel gas 11 is not circulated. Therefore, the fuel gas flow rate is sufficiently smaller than the oxidant gas flow rate, and the fuel gas pressure is low. Loss is not a problem. Therefore, the mist collector 38 is less likely to impair the function of the fuel cell when it is provided in the fuel gas passage than in the oxidant gas passage.

As described above, the molten carbonate fuel cell of the present invention can replenish the carbonate lost by the operation of the cell from the outside of the cell in the form of mist. Further, since the amount of carbonate supplied can be easily increased, it becomes possible to replenish in a short time.

[0053]

As described above, according to the present invention, the carbonate mist produced by the molten carbonate mist producing device is supplied to the gas passage in the separator, and the carbonate mist is collected by the collector plate or the mist collector. Since it is captured, the carbonate lost by the operation of the fuel cell can be efficiently replenished to the unit cell.
Further, in the present invention, since the carbonate can be replenished in the liquid phase, the replenishment time can be significantly shortened as compared with the case of replenishing in the gas phase like vapor. Therefore, it is possible to shorten the time for interrupting the power generation of the battery for replenishing the carbonate.

Further, by supplying the molten carbonate, the molten carbonate fuel cell can maintain the performance for a long time and achieve a long life.

[Brief description of drawings]

FIG. 1 is a structural diagram of a molten carbonate fuel cell of the present invention.

FIG. 2 is an explanatory view of a venturi-type mist generator used as the carbonate mist generator of the present invention.

FIG. 3 is a configuration diagram showing an embodiment in which a venturi-type mist generator as a molten carbonate mist generator of the present invention is incorporated in a fuel gas supply pipe of a fuel cell.

FIG. 4 is an explanatory view of a jet ejector type mist generator used as the carbonate mist generator of the present invention.

FIG. 5 is a configuration diagram showing an embodiment in which a jet ejector type mist generating device as a molten carbonate mist generating device of the present invention is incorporated in a fuel gas supply pipe of a fuel cell.

FIG. 6 is an explanatory diagram when a baffle plate is used as the mist collector of the present invention.

FIG. 7 is a perspective view of an anode current collector plate or a cathode current collector plate in which the mist collector of the present invention is integrated.

FIG. 8 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.

FIG. 9 is a perspective view of an anode current collector plate and a cathode current collector plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single cell 2 Electrolyte matrix 3 Anode electrode 4 Cathode electrode 5 Separator 9 Anode current collector plate 10 Cathode current collector plate 11 Fuel gas 12 Oxidant gas 14 Cell 18 Molten carbonate mist generator 19 Fuel gas flow path 20 Oxidant gas flow Line 21 Venturi type mist generator 26 Fuel cell stack 29 Carbonate reservoir 33 Jet ejector type mist generator 38 Mist collector 39 Baffle plate 40 Molten carbonate mist supply device 42 Fuel gas supply pipe 43 Oxidant gas supply pipe

Claims (8)

[Claims] 1. A plate-shaped unit cell in which an electrolytic matrix is sandwiched between an anode electrode and a cathode electrode, and a fuel gas is passed through a fuel gas channel to the anode electrode of the unit cell, and an oxidant is fed to the cathode electrode. A fuel cell stack in which separators for separating and guiding oxidant gases through gas passages are alternately stacked, a fuel gas supply pipe for supplying fuel gas to the fuel gas passages, and the oxidation An oxidant gas supply pipe for supplying an oxidant gas to the agent gas flow passage, and the fuel gas flow passage in the separator provided in at least one of the fuel gas supply pipe or the oxidant gas supply pipe or A molten carbonate mist supply device for supplying a molten carbonate mist to at least one of the oxidant gas flow paths. battery. 2. The molten carbonate mist supply device, a carbonate reservoir for storing the molten carbonate to be supplied, a gas heater for heating a carrier gas for carrying the molten carbonate, and the melt. And a venturi-type mist generating device for dispersing molten carbonate from the carbonate reservoir in the form of mist and supplying the carrier gas from the gas heater to the fuel gas passage or the oxidant gas passage. The molten carbonate fuel cell according to claim 1, wherein 3. The venturi type mist generating device,
A nozzle to which the carrier gas for carrying the molten carbonate mist is supplied, a venturi having a throat portion with a narrowed flow passage section provided at the outlet of the nozzle, and the molten carbonate provided to the throat portion The molten carbonate fuel cell according to claim 2, further comprising: 4. The molten carbonate mist supply device includes a carbonate reservoir for storing the molten carbonate to be supplied, and the molten carbonate from the molten carbonate reservoir dispersed in a mist form to form the fuel gas flow path. Alternatively, the molten carbonate fuel cell according to claim 1, comprising a jet ejector type mist generating device for supplying to the oxidant gas flow path. 5. The jet ejector type mist generator is provided with a nozzle for injecting the molten carbonate supplied from the carbonate reservoir, and a rotary flow provided in the nozzle for providing the molten carbonate. The molten carbonate fuel cell according to claim 4, further comprising: a spiral blade and an injection port for dispersing and injecting the molten carbonate, which is given a rotating flow by the spiral blade, in a mist form. . 6. The mist collector for changing the flow direction of the molten carbonate mist is provided in the fuel gas passage or the oxidant gas passage inside the separator. Item 5. A molten carbonate fuel cell according to item 5. 7. The molten carbonate fuel cell according to claim 6, wherein the mist collector comprises a plurality of baffles. 8. The mist collector is integrally provided on an anode current collector plate and a cathode current collector plate provided in the separator adjacent to the anode electrode and the cathode electrode. Item 7. A molten carbonate fuel cell according to item 6.