JPH09115539A - Electrolyte replenishing device of layer-built fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically supply electrolyte of a quantity corresponding to a loss quantity of the electrolyte by storing electrolyte disappearing quantity data of a unit cell as a function of a power generation quantity, and controlling a variable speed pump on the basis of a command for an external power generation quantity. SOLUTION: In a layer-built fuel cell 1, an electrolyte replenishing device 30 is provided with plural replenishing tubes 32 whose suction ends are connected to an electrolyte storage tank 31, a variable speed tube pump 33, a disappearing quantity operation part 34 and a pump speed control part 35. First of all, electrolyte loss quantity data of a unit cell 2 corresponding to an operation temperature is stored in the disappearing quantity operation part 34 as a function of a power generation quantity. Rotating speed (a delivery quantity) of the tube pump 33 is controlled on the basis of a command for an external power generation quantity. Electrolyte consumption data corresponding to the command for an external power generation quantity is outputted. This data is converted into rotating speed control output of the variable speed pump 33. The rotating speed of this variable speed pump 33 is controlled in proportion to electrolyte loss quantity data by following a power generation quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated fuel cell comprising a laminated body of unit cells provided with a grooved reservoir plate for holding an electrolyte, and an electrolyte which decreases with the lapse of operating time, according to the decreasing speed thereof. The present invention relates to an electrolyte replenishing device that replenishes from the outside.

[0002]

2. Description of the Related Art In the case of a fuel cell, the power generation reaction is a reaction in which hydrogen and oxygen react to generate water and electrons. For example, in the case of a phosphoric acid fuel cell, an operating temperature of about 190 ° C is maintained. When power is generated, the water generated in the electrode catalyst layer becomes water vapor, permeates the electrode substrate, is discharged into the reaction gas passage, and is discharged out of the system together with the off gas which has finished the reaction. At this time, since the phosphoric acid retained in the matrix exhibits a constant vapor pressure corresponding to the operating temperature, when the water generated in the electrode catalyst layer is vaporized, a slight amount of phosphoric acid vapor is caught in the electrode substrate. It is permeated and discharged into the reaction gas passage, and is discharged out of the system together with the off gas which has finished the reaction. Therefore, the phosphoric acid retained by the matrix gradually decreases with the passage of operating time, which causes the internal resistance of the fuel cell to increase and the output voltage to decrease.
Eventually, the reaction gas may directly react to damage the battery. Therefore, there is known a laminated fuel cell including an electrolyte replenishing device that replenishes the electrolyte lacking in the matrix due to the disappearance of the electrolyte. Further, as the electrolyte replenishing device, an internal replenishing method in which an electrolyte reservoir holding the electrolyte is provided in the unit cell, an external replenishing method in which the electrolyte is replenished from an electrolyte storage tank provided outside the laminated fuel cell, and both are used in combination. The method etc. are known. Further, the external replenishment method is roughly divided into a method using a metering pump and a water head difference method using an electrolyte replenishment tank.In the water head difference method, there are several electrolyte replenishment paths connecting a unit cell and an electrolyte replenishment tank. Ideas have been proposed.

FIG. 7 is a system configuration diagram schematically showing a conventional electrolyte replenishing device for a laminated fuel cell, using a phosphoric acid type fuel cell as an example. The laminated fuel cell 1 comprises a unit cell 2 having a plurality of layers.
And a gas-impermeable separate plate 6 are formed as a laminated body (cell stack). The unit cell 2 is formed by stacking a fuel electrode 4 and an oxidizer electrode (air electrode) 5 with a matrix 3 impregnated with, for example, phosphoric acid 9 serving as an electrolyte in a porous insulating material, and is composed of electrodes of both electrodes. Reaction gas passages 4A and 5A are formed in the electrode base material supporting the catalyst layer in directions orthogonal to each other. By supplying fuel gas to the 4A side and reaction air to the 5A side, the reaction gas passages 4A and 5A are provided between the pair of electrodes 4 and 5. Electric power is generated based on the electrochemical electrode reaction.

Further, an electrolyte replenishment passage 7 communicating with the matrix 3 is formed in both electrodes of each unit cell 2 of the laminated fuel cell 1 or in either electrode (fuel electrode 4 in the figure). Then, using the replenishment passage 7 as an electrolyte reservoir, an electrolyte replenishment pipe 11 having a discharge end 11B communicating with the replenishment passage 7 and a suction end 11 of the replenishment pipe 11.
An electrolyte replenishing device 10 including an electrolyte replenishing tank 12 connected to the A side is provided to replenish the electrolyte deficient in the matrix. In addition, electrolyte reservoirs 12A, 13B, etc. are provided at different height positions in the electrolyte replenishment tank 12 corresponding to the plurality of replenishment pipes 11, and are supplied from an electrolyte storage tank (not shown) connected to the upper portion of the electrolyte tank 12. Electrolyte 9 for each electrolyte reservoir 13
By filling in the order of A and 13B and sequentially overflowing, the height between the liquid level of each electrolyte reservoir and the height of the matrix 3 of the unit cell communicating with it through the replenishment pipe is increased. The level difference of H is maintained.

Therefore, according to the water head difference type electrolyte replenishing device 10 thus constructed, the replenishment pipe is curved in a siphon shape, and the electrolyte 9 having the flow rate determined by the water head difference corresponding to the height difference H is stored in the electrolyte reservoir 13. Therefore, each unit cell 2 can be quantitatively replenished, and the electrolyte 9 deficient in the matrix 3 can be replenished. In addition, the conductive fiber 15 that is hydrophilic to the electrolyte over the entire length of the supply pipe 11
There is also known an electrolyte replenishing device which prevents the electrolyte 9 from running out of liquid in the replenishing pipe 11 by filling the inside of the replenishing pipe 11 and transferring the electrolyte by utilizing the capillary phenomenon (JP-A-61-1).
No. 07667).

Further, a hydrophilic fiber filling material 15 as a liquid running-out prevention means in the supply pipe 11 is configured to be filled in the supply pipe, leaving a portion of the electrolyte reservoir 13 on the supply pipe discharge side lower than the liquid surface. At the rising portion of the siphon-shaped supply pipe, the electrolyte is transferred into the supply pipe 11 without causing liquid drainage due to the sucking action by the capillary action of the filled hydrophilic fibrous filler 15, and the fibrous filler is filled. There is also proposed an electrolyte replenishing device that transfers the electrolyte into the replenishment passage 7 with low resistance due to the difference in the water heads of the electrolyte that fills this falling portion near the discharge end 11B of the replenishment pipe (Japanese Patent Application Laid-Open No. Hei 10 (1999)). 6-36787).

FIG. 8 is a system configuration diagram schematically showing another conventional electrolyte replenishing device for a laminated fuel cell, using a phosphoric acid fuel cell as an example. In the figure, a unit cell 2 of a phosphoric acid fuel cell comprising a stack of a matrix 3 holding phosphoric acid as an electrolyte and a fuel electrode 4 and an oxidizer electrode 5 sandwiching the matrix 3 has a pair of electrodes 4 and 5 Each is composed of an electrode catalyst layer and an electrode base material composed of a flat plate-like porous carbon base material supporting the electrode catalyst layer, and the rib portion is in close contact with the electrode base material and a reaction gas passage is formed between the electrode base material and the electrode base material. 4A, 5A
Is provided with a pair of grooved reservoir plates 8 made of a porous carbon substrate having grooves. The grooved reservoir plates 8 are impregnated with phosphoric acid in advance. Further, the unit cell 2 provided with the grooved reservoir plate 8 is laminated in a plurality of layers with a separate plate 6 made of a gas impermeable carbon plate being interposed therebetween, whereby a laminated fuel cell (stack) having a desired output voltage is obtained. ) 1 is formed.

An electrolyte replenishing device 20 for replenishing an electrolyte from the outside of the laminated fuel cell 1 includes an electrolyte replenishing tank 12, and a guiding tank for connecting the ribbed reservoir plate 8 of each unit cell 2 of the laminated fuel cell 1 to the replenishment tank 12. It is composed of the liquid part 14 and
One end of the liquid guiding part 14 forms a connecting part 24 that is in close contact with the ribbed reservoir plate 21 for a certain length, and the other end is in liquid form from the liquid surface of the electrolyte reservoirs 13A, 13B, etc. 13 of the replenishment tank 12. It is inserted into the electrolyte 9. Here, the ribbed reservoir plate 8 is made of a porous carbon material having a reaction gas passage 4A or 5A on the side in contact with the fuel electrode 4 or the air electrode 5 of the unit cell 2, and the liquid introducing portion 14 is also a ribbed reservoir. Since it is made of a porous carbon material manufactured under the same material and manufacturing conditions as the plate 8, phosphoric acid 9
On the other hand, the liquid conducting portion 14 having a capillary force substantially equal to that of the ribbed reservoir plate 21 is formed, and as a result, the head difference H
An electrolyte replenishing device has been proposed in which an amount of replenishment of electrolyte determined by each unit cell is evenly supplied (Japanese Patent Application No. 7-178334).

[0009]

FIG. 9 is an explanatory view showing the structure of a general laminated fuel cell and its temperature distribution.
In the figure, in order to perform a power generation operation while the laminated fuel cell 1 maintains a predetermined operating temperature (for example, about 190 ° C in a phosphoric acid fuel cell), in the case of FIG. A cooling plate 17 is laminated between the cooling plates, and a cooling medium having a predetermined temperature is passed through a cooling pipe 18 embedded in the cooling plate to cool the cooling pipe. However, there is usually a temperature difference of more than 10 ° C. between the operating temperature T _L of the unit cell 2B in contact with the cooling plate 17 and the temperature T _H of the unit cell 2A located in the center of the block. By the way, the electrolyte impregnated and retained in the matrix of each unit cell shows a constant vapor pressure corresponding to the operating temperature, and the amount of electrolyte lost from the matrix also increases in proportion to the vapor pressure, so that the high temperature unit An uneven distribution of the amount of lost electrolyte occurs, in which the amount of lost electrolyte is large in the cell 2A and small in the low temperature unit cell 2B. The amount of electrolyte loss is also affected by the flow velocity of the reaction gas in the reaction gas passage, and the amount of electrolyte loss increases during operation and during high power operation with high flow velocity, and the amount of electrolyte loss decreases during low power operation. The fluctuation is repeated.

However, in the conventional electrolyte replenishing device using a metering pump or the conventional electrolyte replenishing device shown in FIG. 7, the electrolyte is evenly distributed to each unit cell irrespective of the temperature distribution of the laminated fuel cell and the change in the power generation amount. Since it is configured to be replenished, the high temperature unit cell 2A with a large amount of electrolyte loss easily causes a situation in which the power generation performance is deteriorated due to insufficient electrolyte. Further, in the low temperature unit cell 2B in which the amount of disappeared electrolyte is small, the electrolyte is excessively supplied, and the excess electrolyte overflows into the electrode base material and the reaction gas passage to hinder the permeation of the reaction gas into the electrode catalyst layer. Is likely to occur, and since this state fluctuates in response to changes in the amount of power generation, the excess / deficiency state of the electrolytic mass held by the matrix fluctuates in a complicated manner, and the power generation performance becomes unstable.

On the other hand, in the conventional electrolyte replenishing device shown in FIG. 8, the capillary forces of the grooved reservoir plate and the liquid conducting portion are made substantially equal, so that the electrolyte holding amounts of both can be kept in an equilibrium state. An electrolyte corresponding to the amount of disappearance of the electrolyte is supplied to the grooved reservoir plate. However, since the amount of electrolyte stored in the electrolyte reservoir is reduced by replenishing the electrolyte during operation, it is necessary to replenish the electrolyte reservoir from an electrolyte storage tank (not shown) to supplement the reduction. However, since the operating temperatures of the plurality of unit cells are different from each other, the decreasing rate of the electrolyte is different between the plurality of electrolyte reservoirs, and the electrolyte replenishment timing is also different, which complicates the maintenance work of replenishing the electrolyte to the plurality of electrolyte reservoirs. There's a problem.

An object of the present invention is to provide an electrolyte replenishing device for a laminated fuel cell capable of continuously and automatically supplying an appropriate amount of electrolyte commensurate with the amount of electrolyte lost in each unit cell for a long period of time without excess or deficiency.

[0013]

In order to solve the above-mentioned problems, the present invention according to claim 1 provides a matrix for holding an electrolyte, a fuel electrode sandwiching the matrix, an oxidizer electrode, and the electrodes. An electrolyte storage tank which is connected to a laminated fuel cell comprising a laminated body of a plurality of unit cells having a grooved reservoir plate for forming a reaction gas passage and holding an electrolyte, and which is provided with an electrolyte lacking in the matrix during operation outside. In the electrolyte replenishing device for replenishing from a plurality of unit cells, the discharge end is connected to the grooved reservoir plate of each unit cell, and the suction end is connected to the electrolyte storage tank. Replenishment tube, a variable speed pump connected to the middle of the plurality of replenishment tubes to control the amount of electrolyte replenishment, and the variable speed pump corresponding to the operating temperature. The amount of electrolyte loss data of each cell is stored as a function of the amount of power generation, and a loss amount calculation unit that outputs the corresponding amount of electrolyte loss amount based on an external power generation amount command, and the variable speed based on this output electrolyte loss amount data are output. A pump speed control unit for controlling the rotation speed of the pump is provided, and the electrolyte whose supply amount is determined by the pump speed is constantly supplied to the unit cells in the block.

According to a second aspect of the present invention, in the electrolyte replenishing device for a fuel cell according to the first aspect, the replenishment tube is a flexible tube, and the variable speed pump locally compresses the flexible tube. It is advisable to use a tube pump that controls the amount of electrolyte discharged according to the moving speed of the position. The invention according to claim 3 is the electrolyte replenishing device for a laminated fuel cell according to claim 1,
For each unit cell block whose operating temperature is different from each other, a plurality of supply tubes, a variable speed pump, a disappearance amount calculation unit, and a pump speed control unit are provided as separate systems, and the unit cell block is provided in the disappearance amount calculation unit of each system. It is advisable to store the electrolyte disappearance amount data corresponding to the operating temperature of as a function of the power generation amount.

According to a fourth aspect of the present invention, a matrix holding an electrolyte, a fuel electrode sandwiching the matrix, an oxidizer electrode, and a groove for forming a reaction gas passage between the electrodes and holding the electrolyte are provided. An electrolyte replenishing device that is connected to a laminated fuel cell composed of a laminate of a plurality of unit cells having a reservoir plate and replenishes an electrolyte lacking in the matrix during operation from an electrolyte storage tank provided outside through the grooved reservoir plate. In the above, an outlet valve of the electrolyte storage tank, an electrolyte replenishment tank having a plurality of electrolyte reservoirs that respectively receive a certain amount of electrolyte that flows down from the outlet valve, and a plurality of unit cells whose operating temperatures are substantially equal to each other. The discharge end is connected to the grooved reservoir plate of each unit cell as one block, and the suction end is connected to the plurality of electrolyte reservoirs with the liquid surface. And a plurality of strips of liquid-conducting sections each of which is made of a porous material having a capillary force equivalent to that of the ribbed reservoir plate, and the amount of generated electricity corresponding to the operating temperature of the unit cell in the block. A loss amount calculation unit that stores the data as a function and outputs corresponding electrolyte loss amount data based on the external power generation command, a loss amount integration unit that obtains an integrated value of this output electrolyte loss amount data, and this loss amount integrated value. When the stored electrolytic mass of the electrolyte reservoir is reached, a valve opening / closing control unit that issues an opening command to the outlet valve for a certain period of time is provided.

According to a fifth aspect of the present invention, in the electrolyte replenishing device for a laminated fuel cell according to the fourth aspect, an outlet valve of an electrolyte storage tank and a plurality of outlet valves of an electrolyte storage tank are provided for each unit cell block having different operating temperatures. An electrolyte replenishment tank with an electrolyte reservoir, multiple lines of liquid-conducting parts, a lost amount calculation part, a lost amount integration part, and a valve opening / closing control part are provided as separate systems, and the unit cell block is operated in the lost amount calculation part of each system. It is preferable to store the electrolyte disappearance amount data corresponding to the temperature as a function of the power generation amount.

According to the first aspect of the present invention, if the amount of electrolyte loss data of the unit cell at a predetermined operating temperature is stored as a function of the amount of power generation in the amount-of-disappearance calculation unit, the amount of power generation corresponding to the external amount of power generation command can be used accordingly. The electrolyte disappearance amount data is output. This electrolyte disappearance amount data is converted into a rotation speed control output of the variable speed pump by the pump speed control unit. With this rotation speed control output, the rotation speed of the variable speed pump is proportionally controlled to the electrolyte disappearance amount data that changes in accordance with the power generation amount. Therefore, by connecting the discharge ends of the plurality of supply tubes to the grooved reservoir plate of each unit cell having an operating temperature substantially equal to the above-mentioned predetermined temperature, the amount of electrolyte lost in the unit cell in the block connected to this unit plate. And an appropriate amount of electrolyte that changes according to the amount of power generation is continuously supplied without excess or deficiency.

Here, as in the invention described in claim 2,
If the supply tube is made of a flexible tube having phosphoric acid resistance such as a fluororesin tube and a tube pump is used as the variable speed pump, a highly reliable electrolyte supply device can be easily obtained. Further, as in the invention described in claim 3, an electrolyte replenishing device is provided as a separate system for each of a plurality of unit cell blocks whose operating temperatures are different from each other, and the operating temperature of the unit cell block is set in the disappearance amount calculation unit of each system. By storing the corresponding amount of lost electrolyte data as a function of the amount of power generation, the amount of electrolyte corresponding to the operating temperature in each unit cell in each block follows the amount of power generation, and the electrolyte replenishing device of each system can be used without excess or deficiency. Automatically supplied.

On the other hand, in the invention as set forth in claim 4, since the capillary force of the grooved reservoir plate and the liquid guiding portion are made substantially equal, the liquid guiding portion is maintained so that the electrolyte holding amounts of both are equal to each other. The capillary force absorbs the electrolyte in the electrolyte reservoir. Therefore, the electrolyte corresponding to the amount of electrolyte lost in the matrix is supplied to the unit cells in the block. Further, this replenishment amount is calculated by the loss amount calculation unit configured in the same manner as in claim 1, and the output electrolyte loss amount data is integrated by the loss amount integration unit, so that the electrolyte shortage in the unit cell is stored in the electrolyte reservoir. It is possible to grasp the decrease in the electrolytic mass generated in the electrolyte reservoir by replenishing it from above. Therefore, when the integrated value of the amount of electrolyte loss (in other words, the electrolyte reduction amount of the electrolyte reservoir) reaches the electrolyte retention amount of the electrolyte reservoir, the valve opening / closing control unit issues a command to open the outlet valve of the electrolyte storage tank, thereby supplying electrolyte. The plurality of electrolyte reservoirs in the tank are filled with the electrolyte, and the electrolyte corresponding to the amount of disappearance of the electrolyte in the unit cells in the block is continuously supplied for a long time without excess or deficiency.

Here, in the invention described in claim 5, a plurality of electrolyte replenishing devices for a laminated fuel cell configured as in claim 4 are provided as separate systems for each unit cell block having different operating temperatures, By storing the electrolyte loss amount data corresponding to the operating temperature of the unit cell block as a function of the power generation amount in the loss amount calculation unit of each system, the amount of electrolyte corresponding to the operating temperature is generated in the unit cells in each block. It is supplied without excess or deficiency following the.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Since the members having the same reference numerals as those of the conventional example have the same functions as those of the conventional example, the description thereof will be omitted. FIG. 1 is a system configuration diagram schematically showing an embodiment of an electrolyte replenishing device for a laminated fuel cell according to the present invention, taking a phosphoric acid fuel cell as an example. In the figure, a matrix 2 for holding phosphoric acid 9 as an electrolyte, a fuel gas 4 and an oxidizer electrode 5, which sandwich the matrix, form a reaction gas passage between them and hold phosphoric acid 9. The unit cell 2 having the grooved reservoir plate 8F on the fuel electrode side and the grooved reservoir plate 8A on the oxidant electrode side is laminated by stacking a plurality of layers with a gas-impermeable separate plate 6 interposed therebetween. The battery 1 is formed. The electrolyte replenishing device 30 is
A plurality of supply tubes 32 whose suction ends are connected to the electrolyte storage tank 31, a tube pump 32 as a variable speed pump connected to the middle of the plurality of supply tubes to control the amount of electrolyte supply, and an external power generation command And a pump speed control unit 35 for controlling the rotation speed (discharge amount) of the tube pump 32 based on the above. The discharge end of the supply tube 32 has a plurality of operating temperatures of the laminated fuel cell 1 that are substantially equal to each other. Each unit cell is connected to the grooved reservoir plate 8F on the fuel electrode side of each unit cell by using, for example, a part of the fuel gas passage 4A.

FIG. 2 is a characteristic diagram showing electrolyte loss data stored in advance in the loss calculation unit in the embodiment shown in FIG. In the figure, the amount of phosphoric acid lost per unit time of the unit cell 2 can be obtained by using an equation as a function of the vapor pressure of phosphoric acid determined by the operating temperature and the reaction gas flow rate determined by the power generation amount. As shown in, for example, the high temperature unit cell, the low temperature unit cell, and the medium temperature unit cell are stored in the loss amount calculation unit 34 as the electrolyte loss amount-power generation amount characteristics having different inclinations, and the electrolyte loss amount corresponding to the external power generation amount command is stored. The data 34S can be retrieved.

Further, a laminated fuel cell model in which a plurality of unit cells having an electrode area of a practical scale are laminated so as to be disassembled is used, and the laminated fuel cell model is operated every time a certain period of time is changed by changing the combination of operating temperature and power generation amount. It is also possible to disassemble and measure the unit cell weight, and to summarize the electrolyte loss amount-power generation amount characteristic corresponding to a predetermined operating temperature as an empirical formula from the change in the unit cell weight, and grasp the electrolyte loss amount with high accuracy. it can.

In the embodiment, the loss amount calculation unit 34 stores the amount of electrolyte loss amount of the unit cell at a predetermined operating temperature as a function of the power generation amount in the form of a predetermined formula or an empirical formula, and the external power generation amount command is stored. Based on this, the electrolyte disappearance amount data 34S corresponding to this is output. The electrolyte disappearance amount data 34S is converted by the pump speed control unit 35 into a rotation speed control output 35S of the tube pump 33, and the rotation speed control output 35S changes the rotation speed of the variable speed pump in accordance with the amount of power generation. It is controlled proportionally to the quantity data. Therefore, by connecting the discharge ends of the plurality of supply tubes 32 to the grooved reservoir plate 8F of each unit cell having an operating temperature substantially equal to the above predetermined temperature,
An appropriate amount of electrolyte, which corresponds to the amount of electrolyte lost and changes according to the amount of power generation, is continuously and automatically supplied to the matrix unit 3 connected to the matrix cell 3 via the grooved reservoir plate 8F. .

FIG. 3 is a schematic diagram showing a state in which the electrolyte replenishing device shown in FIG. 1 is applied to a laminated fuel cell having a cooling plate. In the figure, in the laminated fuel cell 1, a cooling plate 17 is laminated for every five layers of unit cells, and a cooling pipe 18
The cooling medium having a predetermined temperature is passed through to discharge the generated heat of power generation. However, as already described with reference to FIG. 9, there is a difference in operating temperature exceeding 10 ° C. between the high temperature unit cell 2A and the low temperature unit cell 2B. Therefore, the laminated fuel cell 1 is divided into a high temperature unit cell block, a medium temperature unit cell block, and a low temperature unit cell block,
An electrolyte replenishing device 30 is provided as a separate system in each unit cell in each block via a replenishing tube 32, and a disappearance amount calculation unit (not shown) of each electrolyte replenishing device 30 has electrolytes corresponding to respective operating temperatures such _as TH and _TL. The loss data is stored as a function of the amount of power generation.

In the laminated fuel cell provided with the electrolyte replenishing device configured as described above, the amount of electrolyte corresponding to the operating temperature is supplied to each unit cell in each block according to the amount of power generation without excess or deficiency. The problems of the prior art such as electrolyte shortage in the high temperature unit cell or excess electrolyte supply failure in the low temperature unit cell are eliminated, and long-term stable operation is possible without causing these failures. It is possible to obtain a laminated fuel cell having high efficiency.

FIG. 4 is a characteristic diagram showing the relationship between the phosphoric acid retention amount of a unit cell and the operating time obtained by connecting the electrolyte replenishing device shown in FIG. 1 to a laminated fuel cell model. As shown in FIG. 3, a laminated fuel cell model including a laminated body of 20 unit cells of 2 m ² and having a cooling plate for every 5 unit cells was formed into a high temperature unit cell block, a medium temperature unit cell block, and a low temperature unit cell block. Each block is operated to generate electricity at a constant temperature in a state where the electrolyte replenishing device 30 is provided in each block, and the laminated fuel cell model is disassembled and the unit cell weight is weighed each time it is operated for a certain time. The amount of reduction is shown as a percentage with the amount of phosphoric acid impregnated at the beginning as 1. As can be seen from the figure, the phosphoric acid retention amount of the unit cell in the block is 1 to 100 hours of operation time.
Over the period of 0000 hours, it is distributed in the range of several percent above and below with 100% at the time of initial impregnation, and corresponds to the amount of disappearance of electrolyte corresponding to the operating temperature of each unit cell block by the electrolyte control device of the example. It can be seen that the phosphoric acid is being replenished just enough.

FIG. 5 is a system configuration diagram schematically showing an electrolyte replenishing device for a laminated fuel cell according to a different embodiment of the present invention, using a phosphoric acid fuel cell as an example. In the figure, an electrolyte replenishment device 40 includes an electrolyte storage tank 31 for storing phosphoric acid 9 as an electrolyte, an outlet valve 41 for the electrolyte storage tank 31, and a plurality of electrolyte storage tanks 31 each for receiving a certain amount of the electrolyte 9 flowing down from the outlet valve 41 and storing a fixed amount of the electrolyte. The electrolyte replenishment tank 12 having the electrolyte reservoirs 13A, 13B, etc. of 13 and the plurality of unit cells 2 having substantially the same operating temperature as one block are connected to the grooved reservoir plate of each unit cell at the discharge end, and the plurality of suction ends are provided. A plurality of lines of the liquid guiding parts 14 respectively inserted into the electrolyte reservoir from above on the liquid surface, and the amount of electrolyte loss data corresponding to the operating temperature of the unit cell in the block are stored as a function of the amount of power generation, and the external power generation command is stored. Based on this, the loss amount calculation unit 42 which outputs the electrolyte loss amount data 42S corresponding thereto and the integrated value 43S of the output electrolyte loss amount data 42S are obtained. A loss amount integrating section 43, and a valve control unit 44 for emitting opening command to the outlet valve 41 when the loss amount integrated value 43S reaches the stored electrolyte mass of the electrolyte reservoir 13.

Here, the plurality of liquid guiding portions 14 are made of a porous material having a capillary force comparable to that of the ribbed reservoir plate, for example, a porous carbon material manufactured under the same material and manufacturing conditions. At this time, the height oh of the liquid conducting portion 21 exposed on the liquid surface of the electrolyte reservoir 13 is kept as low as possible than the suction height due to the capillary force, whereby the transfer of phosphoric acid is facilitated. Further, if the water head difference H with the grooved reservoir plate is made larger than the suction height due to the capillary force, the liquid guiding part 14 sucks the outside air from the outer peripheral surface thereof and causes liquid shortage, so the water head difference H is also due to the capillary force. It is recommended that the height be less than or equal to the siphoning height. By doing this, the electrolyte sucked up from the electrolyte replenishment tank by the liquid guiding section by its capillary force is
The electrolyte is transferred toward the ribbed reservoir plate so that the electrolyte holding amount of the liquid introducing portion is approximately equal to the electrolyte holding amount of the ribbed reservoir plate. At this time, in the matrix of unit cells in a block whose operating temperatures are almost equal, the amount of electrolyte that is proportional to the power generation amount of the laminated fuel cell disappears, but this lost amount is replenished from the grooved reservoir plate and The amount of decrease in the amount of retained electrolyte is supplied from the electrolyte supply device via the liquid conducting section in equilibrium with this. Therefore,
Unlike conventional electrolyte replenishing devices that use the head difference, it corresponds to the amount of phosphoric acid lost in each unit cell without causing troubles such as running out of liquid in the liquid introducing section and obstruction of reaction gas flow due to excessive supply. There is an advantage that the generated power of the fuel cell can be stably maintained by stably supplying the generated phosphoric acid. The liquid guiding section 14 may be provided with a coating layer for blocking its surface from the outside air.

On the other hand, the electrolyte 9 due to the capillary force of the liquid conducting section 14
The replenishment amount of the lost amount calculation unit 4 is the same as that of claim 1.
2 is calculated as a function of the external power generation amount command, and the output electrolyte disappearance amount data 42S is integrated by the disappearance amount integrating unit 43, so that the decrease in the electrolytic mass stored in the electrolyte reservoir 13 is grasped. Therefore, the valve opening / closing control unit 4 confirms that the integrated value of the amount of lost electrolyte has reached the amount of electrolyte retained in the electrolyte reservoir.
4 opens and the outlet valve 41 of the electrolyte storage tank 31 is detected, the plurality of electrolyte reservoirs 1 in the electrolyte replenishment tank 1
The electrolyte is automatically replenished in 3A, 13B, etc., and the advantage that the electrolyte corresponding to the amount of electrolyte lost in the unit cells in the block can be continuously and automatically supplied for a long period without excess or deficiency is obtained.

The electrolyte replenishing device 40 according to this embodiment is
Similar to that shown in FIG. 4, a unit cell block having different operating temperatures of the laminated fuel cell 1 is provided as a separate system, and the electrolyte loss data corresponding to the operating temperature of the unit cell block is provided to the loss calculation unit of each system. By storing as a function of the amount of power generation, the amount of electrolyte corresponding to the operating temperature can be supplied to each unit cell in each block following the amount of power generation without excess or deficiency. In this case, in the electrolyte replenishing device 40 of each system, the volumes (electrolyte effective storage amount) of the plurality of electrolyte reservoirs 13A, 13B and the like 13 included in each electrolyte replenishment tank 12 correspond to the operating temperature of the unit cell block. If the high temperature unit cell block is made large and the low temperature unit cell block is made small, the electrolyte replenishment cycle can be made substantially the same among a plurality of electrolyte replenishing devices, and the electrolyte replenishment tank 12 is common to all systems. It is possible to simplify the configuration of the device by integrating the above into a single unit, and to simplify the configuration of the device by sharing the loss amount calculation unit, the loss amount integration unit, the valve opening / closing control unit, and the outlet valve.

FIG. 6 is a characteristic diagram showing the relationship between the phosphoric acid retention amount of the unit cell and the operating time obtained by connecting the electrolyte replenishing device shown in FIG. 5 to the laminated fuel cell model, and shown in FIG. The phosphoric acid retention amount of each unit cell in each block was measured under the same experimental conditions as in FIG. 4 except that the laminated fuel cell model 40 was used. As is clear from the figure, the phosphoric acid retention amount of each unit cell in each block was distributed in the range of several percent above and below the initial impregnation of 100% over the operating time of 100 hours to 10,000 hours. It can be seen from the electrolyte control device 40 also that the phosphoric acid corresponding to the amount of disappearance of the electrolyte corresponding to the operating temperature of each unit cell block is replenished without excess or deficiency.

[0033]

As described above, in the electrolyte replenishing device for a laminated fuel cell of the present invention, a plurality of unit cells of the laminated fuel cell whose operating temperatures are substantially equal to each other are regarded as one block, and the discharge end is provided on the grooved reservoir plate of each unit cell. A plurality of replenishment tubes connected to each other and a variable speed pump are used, and the rotation speed of the variable speed pump is controlled based on the electrolyte disappearance amount data which is predetermined in accordance with the operating temperature and the power generation amount. As a result, there is provided a fuel cell equipped with an electrolyte replenishing device capable of continuously and automatically supplying an electrolyte proportional to the amount of electrolyte loss generated by following the amount of power generation in unit cells in a block whose operating temperatures are almost equal. be able to.

An electrolyte replenishing device is provided as a separate system for each of a plurality of unit cell blocks having different operating temperatures,
By storing the electrolyte loss data corresponding to the operating temperature of the unit cell block as a function of the power generation amount in the loss calculating unit of each system, the amount corresponding to the operating temperature in the unit cells in the blocks with different operating temperatures can be stored. Will be automatically supplied without excess or deficiency following the amount of power generation, which is a problem with the conventional electrolyte replenishing device that constantly supplies a certain amount of electrolyte regardless of the operating temperature distribution in the laminated fuel cell and the amount of power generation. Insufficient electrolyte in the high temperature unit cell and excessive supply of electrolyte in the low temperature unit cell are eliminated, and fuel with an electrolyte replenishing device that can stably supply the electrolyte shortage without causing a decrease in power generation performance due to these A battery can be provided.

On the other hand, a plurality of unit cells of the laminated fuel cell whose operating temperatures are substantially equal to each other are set as one block, and the unit cell in these blocks is connected to the grooved reservoir plate and the electrolyte reservoir of the electrolyte replenishing tank in the liquid conducting section. , A porous material having a capillary force substantially equal to that of the ribbed reservoir plate was used. As a result, the ribbed reservoir plate and the liquid-conducting portion maintain an equilibrium state of substantially equal electrolyte retention rates,
The unit cell replenishes the amount of electrolyte loss that occurs in response to changes in the amount of power generation, so there is a problem in the conventional electrolyte replenishing device with a water head difference method It is possible to provide a fuel cell provided with an electrolyte replenishing device that can stably supply a shortage of electrolyte without causing the above problem. In addition, the outlet valve of the electrolyte storage tank is opened and closed based on the integrated value of the amount of electrolyte loss determined in advance corresponding to the operating temperature of the unit cells in the block and the amount of power generation, so the electrolyte generated in the electrolyte reservoir due to electrolyte replenishment It is possible to grasp the decrease in the amount of electrolyte sequentially and replenish the electrolyte before the stored electrolytic mass of each electrolyte reservoir becomes zero.Automatic replenishment of the electrolyte makes it possible to replenish the electrolyte to the unit cells in the block for a long time. It is possible to provide a fuel cell provided with an electrolyte replenishing device that can be stably and continuously operated.

Here, an electrolyte replenishing device is provided as a separate system for each of a plurality of unit cell blocks whose operating temperatures are different from each other, and electrolyte loss data corresponding to the operating temperature of the unit cell block is supplied to the loss amount calculating section of each system. If it is stored as a function of the power generation amount, the amount of electrolyte corresponding to the operating temperature will be supplied to the unit cells in the blocks with different operating temperatures in an appropriate amount following the power generation amount. The shortage of electrolyte in the high temperature unit cell or the excessive supply of electrolyte in the low temperature unit cell, which was a problem in the conventional electrolyte replenishment device of the water head difference method that constantly supplies a constant amount of electrolyte regardless of the operating temperature distribution and power generation It is possible to provide a fuel cell provided with an electrolyte replenishing device that is excluded and that can stably supply a shortage of electrolyte without causing a decrease in power generation performance due to these.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram schematically showing an embodiment of an electrolyte replenishing device for a laminated fuel cell according to the present invention, using a phosphoric acid fuel cell as an example.

FIG. 2 is a characteristic diagram schematically showing electrolyte loss data which is stored in advance in a loss calculation unit in the embodiment shown in FIG.

FIG. 3 is a configuration diagram schematically showing an application state of the electrolyte replenishing device shown in FIG. 1 to a laminated fuel cell provided with a cooling plate.

FIG. 4 is a characteristic diagram showing a relationship between a unit cell phosphoric acid retention amount and an operating time obtained by connecting the electrolyte replenishing device shown in FIG. 1 to a laminated fuel cell model.

FIG. 5 is a system configuration diagram schematically showing an electrolyte replenishing device for a laminated fuel cell according to a different embodiment of the present invention, using a phosphoric acid fuel cell as an example.

FIG. 6 is a characteristic diagram showing the relationship between the unit cell phosphoric acid retention and the operating time obtained by connecting the electrolyte replenishing device shown in FIG. 5 to a laminated fuel cell model.

FIG. 7 is a system configuration diagram schematically showing a conventional electrolyte replenishing device for a laminated fuel cell, using a phosphoric acid fuel cell as an example.

FIG. 8 is a system configuration diagram schematically showing a different conventional electrolyte replenishing device for a laminated fuel cell, using a phosphoric acid fuel cell as an example.

FIG. 9 is an explanatory view showing the structure of a general laminated fuel cell and its temperature distribution.

[Explanation of symbols]

 1 Laminated Fuel Cell 2 Unit Cell 3 Matrix 4 Fuel Electrode 5 Oxidizer Electrode 6 Sebacate Plate 8 Grooved Reservoir Plate 9 Electrolyte (Phosphoric Acid) 10 Electrolyte Supply Device 11 Supply Pipe 12 Electrolyte Supply Tank 13 Electrolyte Reservoir 14 Conductive Part 15 Hydrophilic Organic fiber 17 Cooling plate 20 Electrolyte replenishing device 30 Electrolyte replenishing device 31 Electrolyte storage tank 32 Replenishment tube 33 Variable speed pump (tube pump) 34 Disappearance amount calculation unit 35 Pump speed control unit 40 Electrolyte replenishment device 41 Outlet valve 42 Disappearance amount calculation unit 43 Disappearance amount integration unit 44 Valve opening / closing control unit

Claims (5)

[Claims] 1. A plurality of unit cell layers having a matrix for holding an electrolyte, a fuel electrode sandwiching the electrolyte, an oxidizer electrode, and a grooved reservoir plate for forming a reaction gas passage between the electrodes and holding the electrolyte. In the electrolyte replenishing device, which is connected to a laminated fuel cell composed of a laminated body, and replenishes the electrolyte deficient in the matrix from an electrolyte storage tank provided outside during operation, a plurality of the unit cells having substantially the same operating temperature are set as one block. The discharge end is connected to the grooved reservoir plate of each unit cell, and the intake end is connected to a plurality of replenishment tubes connected to the electrolyte storage tank, and is connected between the plurality of replenishment tubes to control the amount of electrolyte replenishment The variable speed pump and the amount of electrolyte loss data of the unit cell corresponding to the operating temperature are stored as a function of the amount of power generation. And a pump speed control unit for controlling the number of revolutions of the variable speed pump based on the output electrolyte loss amount data, and a supply amount depending on the pump speed. An electrolyte replenishing device for a laminated fuel cell, which constantly replenishes an electrolyte that determines the unit cell in a block. 2. The electrolyte replenishing device for a fuel cell according to claim 1, wherein the replenishment tube comprises a flexible tube, and the variable speed pump locally discharges the flexible tube by a moving speed at a position where the flexible tube is locally compressed. An electrolyte replenishing device for a laminated fuel cell, which is a tube pump to be controlled. 3. The electrolyte replenishing device for a laminated fuel cell according to claim 1, wherein a plurality of replenishment tubes, a variable speed pump, a loss calculation unit, and a pump speed control are provided for each unit cell block having different operating temperatures. A separate unit is provided, and the loss calculation unit of each system stores electrolyte loss data corresponding to the operating temperature of the unit cell block as a function of the power generation amount. apparatus. 4. A plurality of unit cells having a matrix holding an electrolyte, a fuel electrode sandwiching the matrix, an oxidizer electrode, and a grooved reservoir plate forming a reaction gas passage between the electrodes and the electrodes and holding the electrolyte. In an electrolyte replenishing device, which is connected to a laminated fuel cell comprising a laminated body of layers, replenishes the electrolyte deficient in the matrix during operation from an electrolyte storage tank provided outside through the grooved reservoir plate, An outlet valve, an electrolyte replenishment tank having a plurality of electrolyte reservoirs that receive a certain amount of electrolyte that flows down from the outlet valve, and store a fixed amount of each electrolyte, and a plurality of the unit cells that have substantially the same operating temperature as one block. The discharge end is connected to the grooved reservoir plate of the cell, and the suction end is inserted into each of the plurality of electrolyte reservoirs from above the liquid surface, A plurality of liquid-conducting parts made of a porous material having a capillary force equivalent to that of a ribbed reservoir plate, and electrolyte loss data corresponding to the operating temperature of the unit cells in the block are stored as a function of the amount of power generation, A loss amount calculation unit that outputs electrolyte loss amount data corresponding thereto based on an external power generation amount command, a loss amount integration unit that obtains an integrated value of this output electrolyte loss amount data, and this loss amount integrated value is the amount of the electrolyte reservoir. An electrolyte replenishing device for a laminated fuel cell, comprising: a valve opening / closing control unit that issues an opening command to the outlet valve for a certain period of time when the stored electrolytic mass is reached. 5. The electrolyte replenishing device for a laminated fuel cell according to claim 4, wherein an outlet valve of an electrolyte storage tank, an electrolyte replenishing tank having a plurality of electrolyte reservoirs, and a plurality of sections for each unit cell block having different operating temperatures. The liquid introduction part, the loss amount calculation part, the loss amount integration part, and the valve opening / closing control part are provided as separate systems, and the loss amount calculation part of each system generates electrolyte loss amount data corresponding to the operating temperature of the unit cell block. An electrolyte replenishing device for a laminated fuel cell, which is stored as a function of quantity.