JPH11283648A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a decrease in the efficiency of converting electric power by a solid polymer type fuel cell by keeping metal ions in circulating water at low concentration which circulates through the solid polymer type fuel cell. SOLUTION: When the operation of this system is started, a timer 116 measures the cumulative drive time of a fuel cell 40, and when the cumulative drive time of the fuel cell 40 has reached a predetermined threshold, the drive of the fuel cell 40 is stopped with a solenoid selector valve 82 opened to drain circulating water in a main tank 56 out of the system through a drain pipe 80. After the drainage is complete, the solenoid selector valve 82 is restored to its closed position to feed pure water from a sub-tank 58 to the main tank 56. Since metal ions in the circulating water concentrate as the drive time of the fuel cell 40 increases, the threshold is set at a time sufficiently shorter than the cumulative drive time required for the circulating water to attain the concentration of metallic ions at which the efficiency of power conversion is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell device provided with a polymer electrolyte fuel cell that generates electric energy by reacting hydrogen in fuel gas with oxygen in air with the intervention of water.

[0002]

2. Description of the Related Art A fuel cell device can generate electric power by supplying fuel gas, and therefore does not require charging before starting to use as compared with a storage battery. Due to such advantages, demand for fuel cell devices is expected to increase in the future as outdoor or emergency power sources.

FIG. 4 shows a structure of a polymer electrolyte fuel cell used in a fuel cell device. Inside a polymer electrolyte fuel cell (hereinafter referred to as a fuel cell) 10, an anode-side air chamber 14 and a cathode-side air chamber 16 having an electrode assembly 12 as a partition are formed. The electrode assembly 12 includes
As shown in FIG. 4, an anode 20 is formed on one surface of the electrolyte membrane 18 and a cathode 22 is formed on the other surface. The anode 20 and the cathode 22 each include a catalyst electrode 24 made of platinum or the like, and a current collector 26 laminated on the catalyst electrode 24. The anode 20 and the cathode 22 are connected to an external circuit 28. I have. Here, a cation exchange resin membrane is used as the electrolyte membrane 18.

A high-purity hydrogen gas is supplied as fuel gas from a cylinder or a reformer (not shown) to the anode side air chamber 14 of the fuel cell 10 configured as described above, and water is supplied by a pump or the like. Is supplied to the cathode-side air chamber 16 by a fan or the like. Anode side air chamber 1
The hydrogen supplied to 4 is ionized on the anode 20;
This hydrogen ion flows through the electrolyte membrane 18 together with water molecules into H ^+.
It moves to the cathode 22 side as xH ₂ O. The hydrogen ions transferred to the cathode 22 react with oxygen in the air and electrons flowing through the external circuit 24 to generate water. Since the electrons flow through the external circuit 28 together with the water generation reaction, the flow of the electrons can be used as DC electric energy.

Here, in order for hydrogen ions to flow smoothly inside the electrolyte membrane 18 with a small resistance, the electrolyte membrane 18
Must be kept moist. On the other hand, the fuel cell 10
Cannot convert all the chemical energy of the supplied hydrogen gas into electric energy, and some of the chemical energy is converted into heat. Therefore, in order to keep the internal temperature of the fuel cell 10 at or below the allowable temperature at which thermal damage does not occur, it is necessary to discharge heat from inside the fuel cell 10 during operation of the fuel cell 10. Therefore, the anode-side air chamber 14 of the fuel cell 10
Is supplied with water together with hydrogen gas to keep the electrolyte membrane 18 in a wet state and to cool the fuel cell 10 with water. Part of the water supplied into the fuel cell 10 becomes steam and is discharged from the fuel cell 10 together with unreacted hydrogen gas and air.
The remainder comprises the fuel cell 1 together with the water generated on the cathode 22.
It is collected at the bottom of 0 and discharged to the outside.

[0006] In a fuel cell device provided with a polymer electrolyte fuel cell as described above, water discharged from the fuel cell is temporarily stored in a water storage tank, and supplied from the water storage tank to the fuel cell by a pump when the fuel cell is driven. Some have a water circulation path.

[0007]

However, in a fuel cell device in which water is circulated to a polymer electrolyte fuel cell by a circulation path, metal ions are circulated from piping or the like as the operating time of the polymer electrolyte fuel cell is increased. And the circulating water becomes steam and is lost from the circulating route, so that the metal ions contained in the circulating water are concentrated. Further, in the polymer electrolyte fuel cell, since the electrolyte membrane for performing hydrogen ion exchange in the electrode assembly is formed of a cation (cation) exchange resin membrane, Fe ⁺⁺ , Cu ⁺⁺ , C
The presence of metal ions (cations) such as a ⁺⁺ inhibits the hydrogen ion exchange reaction. That is, when the metal ion concentration in the circulating water increases to a certain value or more, the resistance of the electrolyte membrane increases in a short time, and the output characteristics of the polymer electrolyte fuel cell decrease with time.

In view of the above, an object of the present invention is to reduce the power conversion efficiency of a polymer electrolyte fuel cell by maintaining a low concentration of metal ions in circulating water circulating in the polymer electrolyte fuel cell. It is to provide a fuel cell device that is prevented.

[0009]

According to a first aspect of the present invention, there is provided a fuel cell device which generates electric energy by reacting hydrogen in a fuel gas with oxygen in the air based on water. A water circulating means connected to a water supply part and a drain part of the polymer electrolyte fuel cell for circulating water to the polymer electrolyte fuel cell; draining circulating water from the water circulating means in an open state and circulating water in a closed state Drainage means for stopping the drainage of water, and when the cumulative value of the drive time during which the polymer electrolyte fuel cell has been driven reaches a predetermined threshold time, open the drainage means to drain the circulating water. Control means for returning the drain means to the closed state after the discharge.

According to the fuel cell device having the above structure, the threshold value of the cumulative value of the driving time defining the timing of draining the circulating water by the draining means is appropriately set, so that the metal ions in the circulating water can be converted into the solid polymer. The circulating water held by the water circulating means can be discharged to the outside before the metal ion concentration is increased so that the effect on the output characteristics of the fuel cell becomes large. A reduction in the power conversion efficiency of the battery is prevented.

Here, the relationship between the driving time of the polymer electrolyte fuel cell and the metal ion concentration can be determined experimentally, and the initial value of the metal ion concentration of water supplied to the water circulation means is substantially constant. Then, it is possible to estimate the accumulated value of the driving time at which the concentration of metal ions in the circulating water decreases the power conversion efficiency of the polymer electrolyte fuel cell. Therefore, if a time sufficiently shorter than the estimated accumulated value of the driving time is set as the threshold value, it is possible to reliably prevent the power conversion efficiency of the polymer electrolyte fuel cell from being reduced by the metal ions.

According to a second aspect of the present invention, there is provided a fuel cell device comprising: a polymer electrolyte fuel cell for generating electric energy by reacting hydrogen in a fuel gas with oxygen in the air with the intervention of water; Water circulating means connected to the water supply section and the drain section of the fuel cell for circulating water to the polymer electrolyte fuel cell; draining the circulating water from the water circulating means in the open state; and stopping the drainage of the circulating water in the closed state. Drainage means, water quality measurement means for measuring the conductivity of circulating water circulating through the polymer electrolyte fuel cell, and, when the conductivity of a predetermined threshold or more is measured by the water quality measurement means, the drainage Control means for returning the drainage means to a closed state after draining the circulating water with the means being in an open state.

[0013] According to the fuel cell device having the above structure, the metal ion in the circulating water can be reduced by appropriately setting the threshold value of the electric conductivity that determines the timing of draining the circulating water by the draining means. Since the circulating water held by the water circulating means can be discharged to the outside before the metal ion concentration becomes high so that the effect on the output characteristics of the polymer electrolyte fuel cell becomes large, the power of the polymer electrolyte fuel cell is affected by the metal ions in the circulating water. A decrease in conversion efficiency is prevented.

Here, the conductivity of the circulating water and the metal ion concentration have a certain correlation, and the metal ion concentration can be accurately estimated by measuring the conductivity of the circulating water.
Therefore, if the conductivity is set sufficiently lower than the conductivity corresponding to the metal ion concentration that reduces the power conversion efficiency of the polymer electrolyte fuel cell, the power conversion efficiency of the polymer electrolyte fuel cell can be increased by the metal ions. Is reliably prevented from decreasing.

According to a third aspect of the present invention, there is provided a fuel cell device.
3. The fuel cell device according to claim 2, further comprising a water supply means for supplying the circulating water to the water circulating means when the circulating water is drained by the draining means.

According to the fuel cell device having the above structure, the pure water or the water from which metal ions have been removed by the water supply means is circulated at the same time as the drainage of the circulating water by the drainage means or after the drainage of the circulating water is completed. By supplying water to the water circulating means as above, the polymer electrolyte fuel cell can be driven normally without lowering the power conversion efficiency due to the influence of metal ions.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(Configuration of First Embodiment) FIGS. 1 to 3 show a fuel cell device according to a first embodiment of the present invention. The fuel cells shown in FIG. 2 and FIG.
Since the basic configuration is the same as that of the polymer electrolyte fuel cell 10 described with reference to FIG. 4, the corresponding members are denoted by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 1, the fuel cell device 30 has an outer casing 32 formed in a substantially rectangular parallelepiped. An operation panel 34 provided with a start / stop button 34A and a door 36 supported to be openable and closable are provided on one side surface of the exterior housing 32.
Are arranged, and an exhaust part 38 is formed below the operation panel 34. The exhaust part 38 has a large number of ventilation holes communicating with an exhaust duct (not shown) in the exterior housing 32. In addition, casters 39 are arranged at the respective corners on the lower surface of the outer casing 32, and the casters 39 facilitate movement of the fuel cell device 30.

As shown in FIG. 2, various members related to power generation, such as a fuel cell 40, are arranged in the outer housing 32, and a cylinder 42 filled with high-pressure hydrogen gas is replaceable. It is stored. Up to two cylinders 42 can be stored in a cylinder storage room in the exterior housing 32.
Opening the door 36 enables replacement.

As shown in FIG. 2, the cylinder 42 has a manual valve 44, which is connected to the anode side air chamber 14 of the fuel cell 40 by a hydrogen supply pipe 46. In the hydrogen supply pipe 46, regulators 48, 50 and an electromagnetic on-off valve 52 are respectively arranged in series in the middle of the pipe, and the first-stage regulator 48 is supplied with a high pressure (1 to 1) supplied from the cylinder 42 through the manual valve 44. 1
The pressure of hydrogen gas of 50 kgf / cm ² ) is reduced to about 1 to ² kgf / cm ² , and the second-stage regulator 50 reduces the hydrogen gas reduced by the first-stage regulator 48 to 0.05 kg / cm ^2.
The pressure is reduced to about Kgf / cm ² . The solenoid on-off valve 52 is opened when a drive voltage is applied (on), and closed when no drive voltage is applied (off). Therefore, when the drive voltage is applied to the solenoid on-off valve 52, the regulator 4
The hydrogen gas decompressed by 8, 50 is supplied to the anode side air chamber 1
4 and supply of hydrogen gas to the anode-side air chamber 14 is interrupted when no drive voltage is applied to the electromagnetic switching valve 52. On the other hand, the sirocco fan 54
Supplies air.

3, a main tank 56 for supplying circulating water to the anode-side air chamber 14 of the fuel cell 40, and pure water is supplied to the main tank 56, as shown in FIG. And a main tank 56 and a sub tank 58 are connected to each other by the pump 6.
And a water supply pipe 64 in which an electromagnetic on-off valve 62 is disposed. Here, the sub-tank 58 stores pure water supplied from outside the apparatus. When the pump 60 is driven and the electromagnetic on-off valve 62 is opened, the pure water in the sub-tank 58 is supplied to the main tank 56.

The main tank 56 is connected to the fuel cell 40 by a water supply pipe 66 as shown in FIG. In the water supply pipe 66, a pump 68 and a filter 70 are arranged in the middle of the pipe. In the fuel cell 40, four water supply joint pipes 76 are arranged at the upper part, and four drainage joint pipes 78 are arranged at the lower part.
Water supply pipes 66 branched on the downstream side of the solenoid on-off valve 70 are connected to 6, respectively.

Inside the fuel cell 40, a water supply circuit (not shown) for supplying water supplied from the four water supply joint pipes 76 to the anode side air chamber 14, and a drainage joint pipe 78 for supplying the anode generated water to the water supply circuit 78. There is provided a drainage circuit (not shown) for discharging water from the water. Here, the fuel cell 40 of the present embodiment houses a plurality of cells in a single casing, the water supply circuit supplies circulating water evenly to the plurality of cells, and the fuel cell 40 tilts in the drain circuit. The circulating water in the cell can be drained through any of the drainage joint pipes 78 so that a part of the cell is not submerged even in the closed state. Also, four drainage joint pipes 78
As shown in FIG. 3, four drain pipes 80 are connected to each other, and water discharged from the drain joint pipe 78 is collected into the main tank 56 through the four drain pipes 80. .

A drain 80 is connected to the bottom of the main tank 56 as shown in FIG.
Reference numeral 6 denotes a drain pipe 80 connected to a drain port (not shown) such as a drain port or a sewage tank outside the apparatus. This drainage pipe 8
An electromagnetic opening / closing valve 82 that is opened when a drive voltage is applied (on) and closed when a drive voltage is not applied (off) is disposed in the middle of the 0 pipe. Therefore, when the open electromagnetic on-off valve 82 is on, the circulating water is drained from the main tank 56 to the drainage receiving portion through the drain pipe 80, and when the open electromagnetic on-off valve 82 is off, the drainage from the main tank 56 stops.

In the fuel cell 40, hydrogen gas and water are supplied to the anode side air chamber 14 and air containing oxygen as a reaction gas is supplied to the cathode side air chamber 16, thereby responding to the power load. A quantity of hydrogen is ionized on the anode 20 and the hydrogen ions are reacted on the cathode 22 with oxygen in the air and electrons flowing through the external circuit to produce water and generate DC electrical energy.

As shown in FIG. 2, the anode side air chamber 1
4 is connected to the main tank 56 by a gas discharge pipe 90, and the main tank 56 is connected to the mixer 96 by a gas discharge pipe 94 in which a needle valve 92 is arranged.

From the anode side air chamber 14, the anode 20
The unreacted hydrogen gas and impurity gases such as nitrogen gas and carbon dioxide gas in the fuel gas (hereinafter referred to as unreacted gas) are circulated through the gas discharge pipe 90 in the circulating water stored in the main tank 56. It flows into the space (gas layer A).
In the main tank 56, moisture is removed from the unreacted gas flowing from the anode-side air chamber 14, and the unreacted gas flows into the mixer 96 through the gas discharge pipe 94. here,
The needle valve 92 is adjusted in advance so as to have a predetermined valve opening. In order to prevent the impurity gas from being concentrated in the anode-side air chamber 14, a small amount of unreacted gas is removed when the fuel cell 40 is driven. It is discharged from the side air chamber 14.

On the other hand, the cathode side air chamber 16 is
The air exhaust pipe 98 is connected to a mixer 96 via an air discharge pipe 98. Therefore, the mixer 96 includes the anode-side air chamber 14.
Unreacted gas from the cathode side air chamber 16 and fan 10
Air from zero flows in. The mixer 96 mixes the unreacted gas containing hydrogen gas and air, dilutes the unreacted gas with air so that the hydrogen concentration becomes 0.01% by volume or less to prevent a hydrogen explosion, and exhausts the exhaust duct. Release to The exhaust gas discharged to the exhaust duct is exhausted from the exhaust portion 38 of the exterior housing 32 to the outside of the device.

When the fuel cell 40 is driven, the water that has moved from the anode-side air chamber 14 to the cathode-side air chamber 16 is discharged together with the air to the mixer 96, and the unreacted gas that has flowed into the mixer 96 from the main tank 56. Since a small amount of water remains, the circulating water in the main tank 56 decreases as the driving time of the fuel cell 40 increases. Main tank 5
6 is provided with a water level sensor 102, which outputs a water level detection signal to the control device 104 when the circulating water in the main tank 56 drops to a predetermined water level.

The control device 104, which has received the water level detection signal from the water level sensor 102, opens the electromagnetic open / close valve 62 of the water supply pipe 64 and simultaneously drives the pump 60 to drive the sub tank 58.
The pure water in the tank is refilled into the main tank 56, and after a lapse of a predetermined time, the electromagnetic on-off valve 62 is closed, and at the same time the pump 60 is stopped. At this time, the control device 104
The amount of water set so that the gas layer A always remains on the circulating water in the tank is replenished to the main tank 56. Also, the solenoid on-off valve 62
The opening / closing of the pump 60 and the driving / stopping of the pump 60 are performed at the same time to prevent the backflow of water from the main tank 56 to the sub-tank 58 whose pressure is higher than the atmospheric pressure due to the unreacted gas.

As shown in FIG. 2, the DC / DC converter 106 and the DC / AC inverter 1
A power supply circuit composed of a power supply circuit 08 and an AC output terminal 110 is connected, and a charging circuit 112 is connected in parallel with the power supply circuit. This charging circuit 112 is connected to a secondary battery 114 that supplies power to the electrical components of the device.

The control device 104 has a built-in timer 116 as shown in FIG.
The drive time for opening the electromagnetic on-off valve 52 of the hydrogen supply pipe 46 is measured by 6. Here, the time when the electromagnetic on-off valve 52 is opened coincides with the time when the fuel cell 40 is driven to output electric energy.

(Operation of First Embodiment) The operation and operation of the fuel cell device 30 of the present embodiment configured as described above will be described.

When the start / stop button 34A is pressed in a state where the operation of the operation panel 34 is stopped, the control device 1
04 and outputs a start signal. Upon receiving the start signal, the control device 104 starts the operation of the device and enables power supply to the external device. The control device 104 supplies the hydrogen gas to the fuel cell 40 by opening the electromagnetic switching valve 52 of the hydrogen supply pipe 46 during operation of the device, and drives the pump 68, the fan 54, and the fan 100 in synchronization with the start of the supply of the hydrogen gas. I do. As a result, the DC power generated by the fuel cell 40 becomes D
After being converted to a predetermined voltage by the C / DC converter 106, the DC / AC
It is converted to V and sent to the AC output terminal 110. Then, the fuel cell 40 generates a DC output according to the power consumption of an external device (not shown) connected to the AC output terminal 110. Here, the fuel cell device 30 of the present embodiment is configured as a self-contained type that does not require external power supply. For this reason, the charging circuit 112 charges the secondary battery 114 with the surplus power of the fuel cell 40, and always stores the power required at the time of startup and at the time of water treatment described later in the secondary battery 114.

When the start / stop button 34A is pressed while the apparatus is operating, the operation panel 34 outputs a stop signal to the control device 104. Upon receiving the stop signal from the operation panel 34, the control device 104 closes the electromagnetic on-off valve 52 to stop the supply of hydrogen gas to the fuel cell 40, and synchronizes the supply of the hydrogen gas with the pump 68, Fan 5
4 and the fan 100 are stopped to stop the operation of the apparatus.

In the fuel cell device 30, as described above, as the driving time of the fuel cell 40 increases, metal ions in the circulating water concentrate. In the fuel cell device 30 of the present embodiment, the circulating water circulating in the fuel cell 40 is replaced with new water at a predetermined cycle in order to prevent the power conversion efficiency of the fuel cell 40 from being reduced by metal ions in the circulating water. Execute the water exchange process.

Next, a control routine by the control device 104 when the water exchange process is performed on the circulating water will be described with reference to FIG. At step 202, the operation of the apparatus is started in response to the start signal from the operation panel 34, and at the same time, at step 204, the timer 116 starts measuring the driving time of the fuel cell 40. Here, the timer 116 includes a non-volatile memory that stores and keeps the measured time even when the operation of the apparatus is stopped, and the cumulative value of the driving time (hereinafter referred to as the cumulative driving time) unless a reset signal is input. Time). In step 206, it is determined whether or not the accumulated driving time measured by the timer 116 has reached a predetermined threshold value.

If it is determined in step 206 that the accumulated driving time is less than the predetermined threshold, step 20
At 8, it is determined whether or not a stop signal has been input from the operation panel 34,
If it is determined that the stop signal has been input, step 21
At 0, the operation of the device is stopped. If it is determined in step 208 that the stop signal has not been input, step 2 is executed.
Return to 06.

On the other hand, if it is determined in step 206 that the accumulated driving time measured by the timer 116 has reached the predetermined threshold value, then in step 212, the timer 1
16 to reset the cumulative driving time to 0, and in steps 214 to 216, close the electromagnetic on-off valve 52 to stop driving the fuel cell 40, and
8 is stopped to stop the water circulation to the fuel cell 40. While the fuel cell 40 is stopped, the secondary battery 114 supplies DC power to the DC / DC converter 106 according to an external load. After this, step 2
At 18, the electromagnetic on-off valve 82 for drainage is opened, and the circulating water in the main tank 56 is drained through the drainage pipe 80 to the drainage receiving section outside the apparatus.

When it is determined in step 220 that the drainage is completed,
In step 222, the electromagnetic on-off valve 82 is closed, and in step 2
At 24, the electromagnetic on-off valve 62 is opened, and at the same time, the pump 60 is driven to supply pure water from the sub tank 58 to the main tank 56. When it is determined in step 226 that the supply of water to the main tank 56 is completed, in step 228, the electromagnetic on-off valve 62 is closed, and at the same time, the pump 60 is stopped to stop supplying water from the sub tank 58 to the main tank 56. Here, in step 220, for example, the elapsed time from when the water level sensor 102 is turned on or when the water level sensor 10 is already on, the elapsed time from the start of drainage reaches a predetermined drainage completion time, and the drainage is performed. Determine completion. In step 226, the completion of water supply is determined, for example, when the elapsed time from when the water level sensor 102 is turned on reaches a predetermined water supply completion time. Further, a water level sensor may be provided at the bottom of the main tank 56 and at a position corresponding to the water level when the water is full, and the completion of drainage and water supply may be determined based on signals from these water level sensors.

In step 230, the pump 68 is driven to restart the water circulation to the fuel cell 40. In step 232, the electromagnetic switching valve 52 is opened to drive the fuel cell 40, and thereafter, the process returns to step 204.

According to the control according to the present embodiment described with reference to FIG. 5, the threshold value of the cumulative driving time that defines the timing of draining the circulating water from the main tank 56 is set to an appropriate value, thereby Metal ions in the fuel cell 40
The circulating water is discharged to the outside of the apparatus before the concentration of the circulating water decreases, and the sub tank 5
Since the pure water is automatically supplied from 8 to the main tank 56, the fuel cell 40 can be driven normally without lowering the power conversion efficiency due to the influence of metal ions in the circulating water.

Here, pure water is stored in the sub tank 58, and pure water is supplied to the main tank 56 from the sub tank 58. Therefore, since the initial value of the metal ion concentration of the water supplied to the main tank 56 is substantially constant, the cumulative driving time at which the metal ions in the circulating water have a concentration that reduces the power conversion efficiency of the fuel cell 40 is experimentally determined. Can be estimated. In this embodiment, the threshold is set to a time that is sufficiently shorter than the cumulative drive time when the circulating water has a metal ion concentration that lowers the power conversion efficiency. Specifically, when the capacity of the main tank 56 is 2 to 3 L in the polymer electrolyte fuel cell 30 having the rated power of 1 kW, the threshold value is set to about 50 hours.

(Configuration of Second Embodiment) FIG. 6 shows a fuel cell device according to a second embodiment of the present invention. In the fuel cell device according to the second embodiment, the same members as those of the fuel cell device 30 according to the first embodiment described with reference to FIGS. Detailed description is omitted.

The difference between the fuel cell device 120 of this embodiment and the fuel cell device 30 of the first embodiment is that the main tank 5
6, the electric conductivity sensor 122 is arranged, and the water treatment device 124 is arranged between the pump 60 and the electromagnetic on-off valve 62 in the water supply pipe 64. As shown in FIG. 6, a conductivity sensor 124 is disposed at the bottom of the main tank 56.
Are connected to the control device 104. Conductivity sensor 12
2 detects the electric conductivity of the circulating water stored in the main tank 56 and outputs a detection signal corresponding to the electric conductivity to the control device 104. Here, since the conductivity is the reciprocal of the specific resistance, the conductivity sensor 122 applies a constant voltage between the pair of electrodes inserted into the main tank 56, and the conductivity of the circulating water is determined by the current value flowing at that time. Is detected. Further, the water treatment device 124 removes metal ions from the water supplied from the sub-tank 58 by the pump 60 and supplies this water to the main tank 56 as circulating water. Here, the water treatment device 1
Reference numeral 24 denotes a storage container (not shown) filled with ion exchange resin. When circulating water is passed through the storage container, cations are circulated from the circulating water by an ion exchange reaction of the ion exchange resin. Metal ions are removed. In this embodiment, a granular cation exchange resin (for example, a high molecular acid in which an acidic group such as an acidic hydroxyl group or a carbosyl group is bonded to a base synthetic resin such as polystyrene) is used as the ion exchange resin.

(Operation of Second Embodiment) The operation and operation of the fuel cell device 120 according to the present embodiment configured as described above will be described.

In the fuel cell device 120, as in the fuel cell device 30 of the first embodiment, as the driving time of the fuel cell 40 increases, metal ions in the circulating water increase. In the fuel cell device 120 of the present embodiment, in order to prevent the power conversion efficiency of the fuel cell 40 from being reduced by metal ions in the circulating water, the circulating water in the main tank 56 based on the detection signal from the conductivity sensor 122 is used. Is discharged to the outside of the apparatus, and a water exchange process of supplying water from the sub tank 58 to the main tank 56 is executed. In this embodiment, the water supply pipe 64 is used.
Since the water treatment device 124 is disposed between the pump 60 and the electromagnetic on-off valve 62 in the above, the water stored in the sub-tank 58 does not necessarily need to be pure water, does not contain insoluble foreign matter, and Tap water or the like may be used as long as the metal ion concentration is lower than a predetermined concentration.

Next, a control routine performed by the control device 104 when performing water treatment on circulating water will be described with reference to FIG. When the operation of the apparatus is started in step 242 in response to the start signal from the operation panel 34, it is determined in step 244 whether or not the conductivity of the circulating water detected by the conductivity sensor 122 is equal to or higher than a predetermined threshold value. I do. If it is determined in step 244 that the conductivity of the circulating water is less than the predetermined threshold value, it is determined in step 246 whether a stop signal has been input from the operation panel 34, and it is determined that the stop signal has been input. If so, the operation of the apparatus is stopped in step 248. If it is determined in step 246 that the stop signal has not been input, the process returns to step 244.

On the other hand, if it is determined in step 246 that the electric conductivity of the circulating water is equal to or greater than the predetermined threshold value, a reset signal is output to the timer 116 in step 252 to reset the accumulated driving time to zero. Steps 254 to 256
Then, the electromagnetic on-off valve 52 is closed to stop the driving of the fuel cell 40, and the pump 68 is stopped to stop the water circulation to the fuel cell 40. During the period when the fuel cell 40 is stopped, the DC / DC converter 1 is operated by the secondary battery 114.
06 is supplied with DC power according to the external load. Thereafter, at step 258, the electromagnetic on-off valve 82 for drainage is opened, and the circulating water in the main tank 56 is drained to the drainage receiving portion outside the apparatus through the drainage pipe 80.

When it is determined in step 260 that the drainage is completed,
In step 262, the electromagnetic on-off valve 82 is closed, and in step 2
At 64, the electromagnetic switch valve 62 is opened, and at the same time, the pump 60 is driven to supply the water from which metal ions have been removed by the water treatment device 124 to the main tank 56. If it is determined in step 266 that the water supply to the main tank 56 is completed, the electromagnetic on-off valve 62 is closed in step 268 and the pump 60
To stop the water supply from the sub tank 58 to the main tank 56. Here, in step 260, for example, the elapsed time from when the water level sensor 102 is turned on, or when the water level sensor 10 is already on, the elapsed time from the start of drainage has reached a predetermined drainage completion time. Determine completion. In step 266, for example, the completion of water supply is determined when the elapsed time from when the water level sensor 102 is turned on reaches a predetermined water supply completion time. Further, a water level sensor may be provided at the bottom of the main tank 56 and at a position corresponding to the water level when the water is full, and the completion of drainage and water supply may be determined based on signals from these water level sensors.

In step 270, the pump 68 is driven to restart the water circulation to the fuel cell 40. In step 272, the electromagnetic switching valve 52 is opened to drive the fuel cell 40, and then the process returns to step 244.

According to the control according to the present embodiment described with reference to FIG. 7, by setting the threshold value of the electric conductivity defining the timing of replacing the circulating water in the main tank 56 to an appropriate value, The circulating water is discharged to the outside of the apparatus before the metal ions in the fuel cell 40 have a concentration lowering the power conversion efficiency of the fuel cell 40, and the water from which the metal ions have been removed from the sub tank 58 to the main tank 56 is automatically discharged after the circulating water is completely drained. Fuel cell 40 without being affected by metal ions in the circulating water, thereby lowering the power conversion efficiency.
Can be driven normally.

Here, the conductivity of the circulating water and the metal ion concentration have a certain correlation, and the conductivity of the circulating water is detected by detecting the conductivity of the circulating water by the conductivity sensor 122 disposed in the main tank 56. It is possible to accurately estimate the metal ion concentration of water. In the present embodiment, the conductivity threshold is set to be sufficiently smaller than the conductivity corresponding to the metal ion concentration that reduces the power conversion efficiency. Specifically, the fuel cell 4
Since the conductivity corresponding to the metal ion concentration that reduces the power conversion efficiency of 0 is about 30 μS / cm, for example, the threshold value of the conductivity is set to 20 μS / cm. Therefore, according to the fuel cell device 120 of the present embodiment, the water treatment is performed when the conductivity of the circulating water becomes 40 μS / cm.
Water treatment at a time when the metal ion concentration is sufficiently low,
Even if the metal ion concentration becomes 20 μS / cm or more, it is possible to reliably prevent the water treatment from being performed. On the other hand, the water stored in the sub-tank 58 may have a metal ion concentration that can be reduced to several μS / cm, preferably 1 μS / cm or less by a single water treatment by the water treatment device 124.

[0055]

As described above, according to the fuel cell device of the present invention, the metal ions in the circulating water circulating in the polymer electrolyte fuel cell can be maintained at a low concentration. It is possible to prevent the power conversion efficiency of the molecular fuel cell from decreasing.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a fuel cell device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the fuel cell device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a fuel cell in a fuel cell device according to a first embodiment of the present invention, and a water supply / drain passage for the fuel cell.

FIG. 4 is a cross-sectional view showing a configuration of a polymer electrolyte fuel cell used in a fuel cell device.

FIG. 5 is a flowchart showing a control routine when circulating water is exchanged in the fuel cell device according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a fuel cell device according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a control routine when circulating water is exchanged in a fuel cell device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 fuel cell (polymer electrolyte fuel cell) 12 electrode assembly 14 anode side air chamber 16 cathode side air chamber 18 electrolyte membrane 20 anode 22 cathode 30 fuel cell device 40 fuel cell (polymer electrolyte fuel cell) 56 main tank (Water circulation means) 58 Sub tank (water supply means) 60 Pump (water supply means) 62 Solenoid on-off valve (water supply means) 56 Main tank (water circulation means) 66 Water supply pipe (water circulation means) 68 Pump (water circulation means) 80 Drain pipe (drainage means) ) 82 Electromagnetic on-off valve (drainage means) 104 Control device (control means) 116 Timer 120 Fuel cell device 122 Conductivity sensor (water quality measurement means) 124 Water treatment device (water supply means)

Claims (3)

[Claims] 1. A polymer electrolyte fuel cell for generating electric energy by reacting hydrogen in a fuel gas with oxygen in the air based on the presence of water, a water supply section and a drainage of the polymer electrolyte fuel cell A water circulating means connected to the unit for circulating water to the polymer electrolyte fuel cell; a water discharging means for draining circulating water from the water circulating means in an open state and stopping the drainage of circulating water in a closed state; When the cumulative value of the drive time during which the fuel cell is driven reaches a predetermined threshold time, the drain means is opened to drain the circulating water, and the control means returns the drain means to the closed state. A fuel cell device comprising: 2. A polymer electrolyte fuel cell that generates electric energy by reacting hydrogen in a fuel gas with oxygen in the air with the intervention of water, a water supply section and a drainage of the polymer electrolyte fuel cell A water circulating means connected to the unit for circulating water to the polymer electrolyte fuel cell; a water discharging means for draining circulating water from the water circulating means in an open state and stopping the drainage of circulating water in a closed state; Water quality measuring means for measuring the conductivity of the circulating water circulating through the fuel cell, and when the conductivity of a predetermined threshold or more is measured by the water quality measuring means, the drainage means is opened to circulate the water. And a control means for returning the drain means to a closed state after draining. 3. The fuel cell device according to claim 1, further comprising a water supply means for supplying circulating water to the water circulating means when the circulating water is drained by the draining means.