JP2006278168A - Fuel cell system - Google Patents

Abstract

A fuel cell system that maintains and stabilizes output characteristics without temporarily stopping operation.
When a monitor 18 monitors the usage state of an FC stack 10 and determines that the reaction water is discharged into the gas flow path and clogging occurs, the amount of the reaction water is estimated and the reaction water is estimated. The amount of drainage maintenance agent added according to the discharge amount is calculated, and the flow controller 14 is instructed to supply the required amount of drainage maintenance agent from the drainage maintenance agent storage tank 12. In accordance with an instruction from the monitor 18, the flow rate controller 14 supplies a required amount of drainage maintenance agent from the drainage maintenance agent storage tank 12 to the oxidant gas supply means 16. In the oxidant gas supply means 16, the waste water maintenance agent is mixed with the oxidant gas and supplied to the FC stack 10. The reaction water, the discharge maintenance agent, and the discharge oxidant gas discharged from the FC stack 10 are separated by the recovery means 20 into a waste water maintenance agent, reaction water, and discharge oxidant gas.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system, and more particularly to an improvement in a fuel cell system that makes it easy to eliminate reaction water generated during power generation and maintains and stabilizes the power generation efficiency of the fuel cell.

  For example, as shown in FIG. 8, a polymer electrolyte fuel cell is a joined body (MEA: Membrane Electrode) in which an electrolyte membrane 52 made of a solid polymer membrane is sandwiched between two electrodes, a fuel electrode 50 and an air electrode 54. Assembly) is a minimum unit of a cell sandwiched between two separators 30, and usually a plurality of cells are stacked to form a fuel cell stack (FC stack) to obtain a high voltage.

The power generation mechanism of the polymer electrolyte fuel cell generally includes a fuel gas (anode side electrode) 50 containing a fuel gas, such as a hydrogen-containing gas, and an air electrode (cathode side electrode) 54 containing an oxidant gas such as a main gas. Is supplied with gas or air containing oxygen (O ₂ ). The hydrogen-containing gas is supplied to the fuel electrode 50 through a fine groove processed on the surface of the separator 30, and is decomposed into electrons and hydrogen ions (H ⁺ ) by the action of the catalyst of the electrode. The electrons move from the fuel electrode 50 to the air electrode 54 through an external circuit, and produce an electric current. On the other hand, hydrogen ions (H ⁺ ) pass through the electrolyte membrane 52 to reach the air electrode 54 and combine with oxygen and electrons that have passed through the external circuit to become reaction water (H ₂ O). Heat generated simultaneously with the bonding reaction of hydrogen (H ₂ ), oxygen (O ₂ ), and electrons is recovered by cooling water. Further, water generated on the cathode side with the air electrode 54 (hereinafter referred to as “reaction water”) is discharged from the cathode side.

  As shown in FIG. 8, during operation of the fuel cell (during power generation), reaction water is generated at a portion in contact with the electrolyte membrane 52 on the surface of the air electrode 54. When the reaction water cannot be efficiently discharged out of the fuel cell system along with the operation of the fuel cell, the reaction water stays in the space between the diffusion layer of the air electrode 54 and the separator 30, and as a result, The diffusion of the reaction gas, particularly the oxidant gas, is hindered and a so-called flatting phenomenon occurs. In such a case, the power generation efficiency of the fuel cell tended to decrease.

  Therefore, some ideas for efficiently discharging the reaction water from the fuel cell have been proposed. For example, Patent Document 1 proposes to provide a coating layer, particularly a hydrophilic polymer layer, having a contact angle with water of 40 degrees or less on the surface of a separator molded body of a fuel cell. Is proposed to improve the wettability of the separator surface by irradiating the surface of a carbon-based separator for fuel cells with vacuum ultraviolet light. A fuel cell using a carbon fiber electrode material having a layer made of conductive fine particles and having a contact angle with water on one side of 108 degrees or more as an electrode has been proposed.

  However, in the separators proposed in Patent Documents 1 and 2, the hydrophilic surface is gradually peeled off by the reaction water with the operation time of the fuel cell, and as a result, the hydrophilic performance of the surface is lowered. It has been difficult to maintain the drainage performance of the battery over a long period of time. Further, the carbon electrode material proposed in Patent Document 3 also has a water-repellent resin on its surface that gradually deteriorates with the operation of the fuel cell, and similarly maintains the drainage in the fuel cell for a long time. It was difficult.

  On the other hand, in Patent Document 4, when the catalyst layer of the cathode electrode becomes excessively wet during the operation of the phosphoric acid fuel cell, and the battery output characteristics are deteriorated, the unit cell voltage is predetermined as shown in FIG. The limit value is compared and determined (S200), and when the generated voltage of the unit cell becomes equal to or less than the limit value, it is determined that the battery output characteristics are deteriorated due to excessive wetting of the catalyst layer of the cathode side electrode, and the temperature rise of the fuel cell The operation of the fuel cell is temporarily stopped (S202), the supply of the oxidant gas to the cathode side electrode is stopped, and then the flow of nitrogen gas to the cathode side electrode is started and remains on the cathode side electrode. The oxygen content of the oxidant gas is purged (S204), and then the nitrogen gas is sufficiently circulated to the cathode side electrode. Then, the hydrogen gas is circulated as the hydrophilic functional group removal gas, and the cathode side electrode is Hydrogen reduction treatment (S206), the hydrophilic functional groups generated on the surface of the support carbon in the cathode side electrode catalyst layer are reduced and removed, and then the nitrogen gas is circulated again to the cathode side electrode to leave the hydrophilicity remaining on the cathode side electrode. Hydrogen that is a functional group removal gas is purged (S208), and the operation of the fuel cell is restarted (S210).

JP 2000-251903 A JP 2003-142116 A JP 2003-213563 A JP 7-307161 A

  However, in the fuel cell operation method proposed in Patent Document 4, the fuel cell operation must be stopped at any time to improve the wettability of the catalyst layer of the cathode electrode, and the operation efficiency of the fuel cell is remarkably increased. There was a risk of damage. Furthermore, when hydrogen is used as the hydrophilic functional group removal gas, hydrogen gas is carefully removed from the oxidant gas flow path by nitrogen gas in order to avoid encountering this hydrogen gas and the oxidant gas supplied later during operation. Therefore, the operation stop time is increased, and the operation efficiency of the fuel cell may be lowered.

  The present invention has been made in view of the above problems, and provides a fuel cell system that satisfactorily discharges reaction water from the fuel cell and maintains and stabilizes the operation efficiency of the fuel cell system.

  In order to achieve the above object, the fuel cell system of the present invention has the following features.

  (1) In a fuel cell system having a fuel cell in which a cell composed of a joined body having a fuel electrode and an air electrode on an electrolyte membrane and a pair of separators sandwiching the joined body, the fuel cell includes A fuel cell system having drainage maintenance agent supply means for supplying a drainage maintenance agent for maintaining drainage in the cell.

  With the above configuration, the waste water maintenance agent efficiently discharges the reaction water in the cell outside the fuel cell system without stopping the operation of the fuel cell, so that the flattening phenomenon hardly occurs and the output characteristics of the fuel cell are maintained. It can be stabilized.

  (2) A fuel cell formed by laminating a cell including a joined body having a fuel electrode and an air electrode on an electrolyte membrane, and a pair of separators sandwiching the joined body, and supplying a reaction gas to the fuel cell In the fuel cell system comprising a reaction gas supply means, a waste water maintenance agent supply means for supplying a waste water maintenance agent for maintaining drainage in the cell to the reaction gas supplied by the reaction gas supply means Is a fuel cell system.

  By supplying the wastewater maintenance agent to the reaction gas and supplying it into the fuel cell together with the reaction gas, the wastewater maintenance agent is also uniformly diffused on the surface of the electrode diffusion layer and the separator as the reaction gas diffuses. As a result, the discharge of the reaction water present on the electrode diffusion layer surface and the separator surface is promoted, and the deterioration of the output characteristics of the fuel cell can be suppressed.

  (3) In the fuel cell system according to the above (1) or (2), the fuel cell system further includes a monitor for monitoring a use state of the fuel cell, and according to the use state of the fuel cell obtained from the monitor, A drainage maintenance agent is supplied to the fuel cell from the drainage maintenance agent supply means.

  By monitoring the use state of the fuel cell by the monitor, the wettability of the diffusion layer surface of the electrode of the cell in the fuel cell and the separator can be grasped. Thereby, when the discharge of the reaction water is delayed due to excessive wetting, the drainage maintenance agent can be appropriately supplied to the fuel cell, so that the wettability can be maintained in a suitable state. The output characteristics can be maintained and stabilized.

  (4) In the fuel cell system according to any one of (1) to (3) above, an exhaust gas flow channel for circulating exhaust gas discharged from the fuel cell, and an exhaust gas flow channel on the exhaust gas flow channel And a collecting means for collecting the waste water maintenance agent.

  By collecting the drainage maintenance agent, it is possible to provide a fuel cell system that can be reused and the cost can be reduced more efficiently.

  (5) In the fuel cell system according to any one of (1) to (4), the drainage maintenance agent is a surface tension reducing agent that reduces the surface tension of the reaction water generated in the cell. .

  In general, the surface of the separator is highly hydrophobic and is in a situation where reaction water adheres and is not easily discharged. Therefore, by supplying a surface tension reducing agent for reducing the surface tension of the reaction water to the fuel cell, the contact angle of the reaction water staying on the separator surface with respect to the separator can be reduced and discharged efficiently.

  (6) In the fuel cell system according to the above (5), the surface tension reducing agent is at least one agent selected from the group consisting of alcohols and surfactants.

  The surface tension reducing agent is easily dissolved in the reaction water and can reduce the surface tension of the reaction water, and is a natural agent as compared with an organic solvent.

  (7) In the fuel cell system according to any one of (1) to (6), the drainage maintenance supply unit supplies the drainage maintenance agent to the cathode side having the air electrode.

  As described above, reaction water is generated on the cathode side in the fuel cell. Therefore, the reaction water can be efficiently discharged by supplying the drainage maintenance agent to the cathode side.

  According to the present invention, since the reaction water in the cell is efficiently discharged out of the fuel cell system without stopping the operation of the fuel cell by the drainage maintenance agent, the flattening phenomenon hardly occurs, and the output of the fuel cell The characteristics can be maintained and stabilized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the fuel cell system of the present embodiment includes an assembly (MEA: Membrane Electrode Assembly) in which an electrolyte membrane made of a solid polymer membrane is sandwiched between two electrodes, a fuel electrode and an air electrode. Further, a cell sandwiched between two separators is set as a minimum unit, and usually, a fuel cell stack (hereinafter referred to as “FC stack”) 10 in which a plurality of cells are stacked to form a stack, and a drainage maintenance agent are stored. The waste water maintenance agent storage tank 12, the flow rate controller 14 for controlling the flow rate of the waste water maintenance agent supplied from the waste water maintenance agent storage tank 12, and the waste water maintenance agent and oxidant gas supplied from the flow rate controller 14 are mixed. An oxidant gas supply means 16 for supplying an oxidant gas supply path of the FC stack 10 and a monitor for monitoring the use state of the FC stack 10 18 and a recovery means 20 for recovering the wastewater maintenance agent from the reaction water discharged from the FC stack 10, the wastewater maintenance agent, and the discharged oxidant gas.

  Next, the operation of the fuel cell system according to the present embodiment will be described with reference to FIGS. 1 and 3.

  The use state of the FC stack 10 is monitored by the monitor 18 (S100). In the monitor 18, it is determined that the reaction water is discharged in the gas flow path and the water is clogged, and that the drainage maintenance agent needs to be added. In the case (S102), the amount of the reaction water is estimated, the amount of the waste water maintenance agent added according to the discharge amount of the reaction water is calculated, and the required amount of the waste water maintenance agent is supplied from the waste water maintenance agent storage tank 12 to the flow rate controller 14. Is supplied (S104). Receiving the instruction from the monitor 18, the flow controller 14 supplies a required amount of the waste water maintenance agent from the waste water maintenance agent storage tank 12 to the oxidant gas supply means 16 (S106). Here, the supply of the drainage maintenance agent in the flow rate controller 14 may be either intermittent or continuous, but when intermittently supplied, the consumption of the drainage maintenance agent is suppressed compared to the continuous supply. Can do. Next, in the oxidant gas supply means 16, the waste water maintenance agent is mixed with the oxidant gas and supplied to the oxidant gas supply path of the FC stack 10. As a result, with the diffusion of the oxidant gas, the drainage maintenance agent is supplied to the oxidant gas discharge passage, and excess reaction water at the air electrode (cathode side) can be discharged out of the fuel cell system. The output characteristics can be maintained and stabilized. Further, the reaction water, the discharge maintenance agent, and the discharge oxidant gas discharged from the oxidant gas discharge channel of the FC stack 10 are reacted with the waste water maintenance agent in the recovery means 20 provided on the oxidant gas discharge channel. Separated into water and discharged oxidant gas, the drainage maintenance agent may be recovered and returned to the drainage maintenance agent storage tank 12, for example.

  Further, in the other fuel cell system of the present embodiment shown in FIG. 2, the reaction water, the drainage maintenance agent, and part or all of the discharged oxidant gas discharged from the FC stack 10 are supplied to the oxidant gas supply means 16. Except for the returning configuration, the fuel cell system has the same configuration as that shown in FIG.

  Next, the operation of the fuel cell system according to the present embodiment will be described with reference to FIGS.

  The use state of the FC stack 10 is monitored by the monitor 18 (S100), and the monitor 18 measures the humidity of the exhaust gas of the cells in the fuel cell in particular, and the reaction water is discharged in the gas flow path, resulting in water clogging. Then, when it is determined that the addition of the drainage maintenance agent is necessary (S102), the amount of the reaction water is estimated and the addition amount of the drainage maintenance agent according to the discharge amount of the reaction water is calculated, and the flow rate is calculated. The controller 14 is instructed to supply a necessary amount of drainage maintenance agent from the drainage maintenance agent storage tank 12 (S104). Receiving the instruction from the monitor 18, the flow controller 14 supplies a required amount of the waste water maintenance agent from the waste water maintenance agent storage tank 12 to the oxidant gas supply means 16 (S106). Here, the supply of the drainage maintenance agent in the flow rate controller 14 may be either intermittent or continuous. However, when intermittently supplied, the consumption of the drainage maintenance agent is suppressed compared to the continuous supply. be able to. Next, in the oxidant gas supply means 16, the waste water maintenance agent is mixed with the oxidant gas and supplied to the oxidant gas supply path of the FC stack 10. As a result, with the diffusion of the oxidant gas, the drainage maintenance agent is supplied to the oxidant gas discharge passage, and excess reaction water at the air electrode (cathode side) can be discharged out of the fuel cell system. The output characteristics can be maintained and stabilized. Further, the reaction water, the discharge maintaining agent, and a part or all of the discharged oxidant gas discharged from the oxidant gas discharge flow path of the FC stack 10 are appropriately supplied to the oxidant gas supply means 16, and again the FC stack. 10 is supplied. On the other hand, when the supply of the wastewater maintenance agent to the FC stack 10 is excessive, in the recovery means 20 provided on the oxidant gas discharge flow path, the wastewater maintenance agent is separated into the reaction water and the discharge oxidant gas, The drainage maintenance agent is collected and may be returned to the drainage maintenance agent storage tank 12, for example.

  The drainage maintenance agent (hydrophilic maintenance agent) improves the hydrophilicity of the gas flow path of the cell, and preferably maintains the hydrophilicity of the surface of the gas flow path formed in the separator 30. is there. Furthermore, the drainage maintenance agent (hydrophilic maintenance agent) is preferably a surface tension reducing agent that reduces the surface tension of the reaction water generated in the cell, and the surface tension reducing agent is selected from alcohols and surfactants. Desirably, the drug is at least one drug selected from the group consisting of: Moreover, as said alcohol, C6 or less alcohol is preferable, More preferably, it is ethanol. The surfactant may be any of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant, but does not contain a metal ion, nitrogen atom, or phosphorus atom. Are preferred, more preferred are nonionic surfactants, and nonionic surfactants having a short chain length are desirable. A washer fluid mounted on a vehicle may be used as the drainage maintenance agent. In such a case, the drainage maintenance agent storage tank 12 need not be provided separately, and the fuel cell system can be made compact.

In particular, as shown in FIG. 4, the drainage maintenance agent reduces the surface tension of the reaction water with respect to the surface of the separator 30 from θs to θs ′, where θs ′ is preferably 90 degrees or less. and surface tension of the water of reaction against the surface of the gas diffusion layer 40 of the electrode in the cell is 'be reduced to its theta _GDL' theta _GDL from theta _GDL it is desired that a drug to be more than 90 degrees . By setting θs ′ and θ _GDL ′ within the above ranges, the reaction water that adheres to the separator and prevents gas diffusion is efficiently discharged out of the fuel cell system while maintaining sufficient water repellency in the gas diffusion layer of the electrode. be able to. Moreover, it is desirable that the drainage maintenance agent is a drug that hardly permeates the electrode diffusion layer.

  Further, the monitor 18 indicates whether or not a fuel cell has been used, for example, the elapsed use time of the fuel cell, the power generation state of the fuel cell, the cell temperature in the fuel cell, and the presence or absence of a flattening phenomenon due to the power generation characteristics of the fuel cell. Measuring.

  More specifically, when the “elapsed time of use (operation) of fuel cell” is used, the monitor 18 has a clock function and is measured in advance and set as “time limit of elapsed time of use (operation)”. When the time when the electrode diffusion layer in the fuel cell is excessively wetted is necessary, the flow rate controller 14 is required depending on the amount of reaction water estimated to be generated during the time when the electrode diffusion layer is excessively wetted. What is necessary is just a monitor which instruct | indicates to supply the quantity of waste_water | drain maintenance agents.

  Further, when the “power generation state of the fuel cell” is used, the monitor 18 has a function of an ammeter that measures the output current of the fuel cell, and can estimate the reaction water according to the amount of current. What is necessary is just a monitor which instruct | indicates to the flow controller 14 to supply the required amount of waste_water | drain maintenance agent according to the amount of reaction water, when the amount of the reaction water becomes.

  In addition, when the “cell temperature in the fuel cell” is used, the monitor 18 has a temperature measurement function, and the cell temperature during normal operation, for example, 80 ° C. is reduced to a threshold cell temperature or less, for example, 30 ° C. or less. Supply the required amount of waste water maintenance agent according to the amount of reaction water estimated to be generated below the threshold cell temperature based on the relationship between the cell temperature measured in advance and the amount of reaction water. As long as it is a monitor, the flow controller 14 may be instructed.

  Further, in the case of using “determination of the presence or absence of a flattening phenomenon based on the power generation characteristics of the fuel cell”, the monitor 18 has a voltage measurement function, and previously measures the voltage value at which the flattening phenomenon occurs in the fuel cell. A voltage value is set as a threshold voltage value, and when this threshold voltage value is reached, a required amount of drainage maintenance agent is supplied to the flow rate controller 14 according to the amount of reaction water estimated to be generated in the flatting phenomenon. Any monitor that instructs to supply it may be used.

  In the present embodiment, the monitor 18 is more preferably a monitor having a current measurement function, a cell temperature measurement function, and a function capable of measuring the amount of reaction gas supplied, and a reaction generated according to the current amount and the reaction gas flow rate. The amount of water can be accurately estimated by calculation, and the amount of reaction water remaining in the cell can be calculated from the cell temperature. As a result, a more accurate amount of the waste water maintenance agent can be supplied to the staying reaction water.

  The monitor 18 is not limited to this. For example, the reaction water inside the cell is determined from the cell internal environment, that is, the cell temperature, the outside air temperature, the cell load, the stoichiometric ratio (stoichiometric ratio), and the operation history. Even if it is a monitor that can estimate the amount, it may also be a monitor that has map information in which the internal environment of the cell is mapped in advance and can estimate the amount of reaction water based on this map information, It may be a monitor that measures the pressure loss due to the clogging of the FC stack and estimates the amount of reaction water from this pressure loss.

  Moreover, it is preferable that 0-15 weight% of waste_water | drain maintenance agents are added with respect to the quantity of the reaction water which should be discharged | emitted. Normally, adding a drainage maintenance agent exceeding 50% by weight with respect to the amount of reaction water to be discharged improves the wettability of the separator and improves the drainage of the reaction water, but the water contacts the electrode diffusion layer. Since the corner becomes smaller, the water repellency of the diffusion layer decreases, the output of the fuel cell may decrease, and the drainage maintenance agent may permeate into the diffusion layer of the electrode.

  The oxidant gas supply means of the present embodiment will be specifically described below with reference to FIGS.

  FIG. 5 shows an example of an injection type oxidant gas supply means 16a as the oxidant gas supply means. As shown in FIG. 5, the oxidant gas supply means 16a includes an injection nozzle 22 for injecting the waste water maintenance agent supplied from the flow controller in the form of a mist and oxidation so as to be orthogonal to the injection direction of the waste water maintenance agent. An oxidant gas introduction port 24 for introducing the oxidant gas into the oxidant gas supply means 16a is provided. Therefore, the required amount of the waste water maintenance agent is injected from the injection nozzle 22 and diffused in a mist form, and the oxidant gas is introduced into this mist-like diffusion region. Therefore, it is supplied to the FC stack 10 in a uniformly dispersed state. Thereby, the mist-like drainage maintenance agent is dissolved in the reaction water, the contact angle of the reaction water with respect to the separator is reduced, and the discharge of the reaction water is improved.

  FIG. 6 shows an example of a carburetor type oxidant gas supply unit 16b as the oxidant gas supply unit. As shown in FIG. 6, the oxidant gas supply means 16b has a wastewater maintenance agent inlet 32 for introducing the wastewater maintenance agent supplied from the flow controller into the oxidant gas supply means 16b, and the pressure of the oxidant gas. There is provided a pressure adjusting valve 28 for adjusting and introducing the oxidant gas to the oxidant gas supply means 16b through the oxidant gas introduction port 24. Therefore, by adjusting the pressure of the oxidant gas introduced into the oxidant gas supply means 16b by the pressure adjustment valve 28, a necessary amount of the wastewater maintenance agent is supplied from the drainage maintenance agent liquid level in the oxidant gas supply means 16b. It is possible to supply the FC stack 10 with the waste gas-maintaining agent-mixed oxidant gas that is drawn at a negative pressure corresponding to the moving speed of the oxidant gas and is uniformly dispersed. Thereby, the waste water maintenance agent uniformly dispersed in the oxidant gas is dissolved in the reaction water, the contact angle of the reaction water with respect to the separator is reduced, and as a result, the discharge of the reaction water is improved.

  FIG. 7 shows an example of a bubbling type oxidant gas supply unit 16c as the oxidant gas supply unit. As shown in FIG. 7, the oxidant gas supply means 16c has a wastewater maintenance agent inlet 32 for introducing the wastewater maintenance agent supplied from the flow controller into the oxidant gas supply means 16c, and the pressure of the oxidant gas. A pressure adjusting valve 28 for introducing a part of the oxidant gas into the oxidant gas supply means 16c through the oxidant gas introduction port 24, and a oxidant gas introduction port 34 by adjusting the pressure of the oxidant gas. And a pressure regulating valve 38 for introducing a part of the oxidant gas into the oxidant gas supply means 16c. Further, the oxidant gas inlet 34 is provided on the bottom surface of the oxidant gas supply means 16c. Therefore, the oxidant gas pressure-adjusted by the pressure adjustment valve 38 from the oxidant gas inlet 34 is made of a drainage maintenance agent stored in a fixed amount in the oxidant gas supply means 16c via the oxidant gas inlet 34. The flow of the oxidant gas introduced into the oxidant gas supply means 16b by the pressure regulating valve 28 when the bubbles of the oxidant gas are introduced into the liquid and bounced up and bounced to the liquid level. Therefore, the oxidant gas is supplied to the FC stack 10 in a uniformly dispersed state. Thereby, the waste water maintenance agent uniformly dispersed in the oxidant gas is dissolved in the reaction water, the contact angle of the reaction water with respect to the separator is reduced, and as a result, the discharge of the reaction water is improved.

  Next, the recovery means 20 in the fuel cell system of the present embodiment will be described with reference to FIG.

  The recovery unit 20 has a heating unit in the pressure vessel and, if necessary, a decompression unit. When reaction water, drainage maintenance agent, and exhaust oxidant gas are introduced into the recovery means 20 from the FC stack 10, they are stored for a certain period of time near 25 ° C., separated into a liquid phase and a gas phase, and contained in the gas phase. Oxidant gas is discharged. Next, when the heating means is used for the liquid phase remaining in the recovery means 20 and the temperature of the drainage maintenance agent is vaporized, for example, ethanol is used as the drainage maintenance agent, if it is methanol, it is 64 ° C. or more and 100 ° C. or less. If it is ethanol, it is heated and controlled at a temperature of 78 ° C. or higher and 100 ° C. or lower, and the waste water retention agent is distilled and recovered separately from water. Here, if the decompression means is used, the heating temperature by the heating means can be lowered. In the case where a surfactant or a washer liquid is used as a drainage maintenance agent, it is difficult to separate it from water as compared with the above-described ethanols, so that the reaction discharged from the FC stack 10 as shown in FIG. It is more efficient to return the mixture of the water, the drainage maintenance agent, and the discharged oxidant gas to the oxidant gas supply means 16 again and reuse it.

  In addition, since ethanol or washer fluid has extremely low toxicity, when ethanol or washer fluid is used as a drainage maintenance agent, it may be discharged outside the fuel cell system without being collected by the collecting means 20 in some cases. Permissible.

  As mentioned above, the introduction of the drainage maintenance agent from the cathode side where the reaction water is generated has been described. However, the present invention is not limited to this, and the anode side also has a fuel gas supply means as shown in FIGS. A configuration for introducing a maintenance agent may be provided.

  The fuel cell system of the present invention is effective for any application as long as it uses a fuel cell, but can be used particularly for a fuel cell for vehicles.

It is a block diagram which shows the structure of the one aspect | mode of the fuel cell system of this invention. It is a block diagram which shows the structure of the other aspect of the fuel cell system of this invention. It is a flowchart explaining an example of supply operation | movement of the waste_water | drain maintenance agent in the fuel cell system of this invention. It is a figure explaining the change of the contact angle of the water with respect to the separator and gas diffusion layer before addition of a waste_water | drain maintenance agent, and after addition. It is a figure explaining the structure of an example of the oxidizing agent gas supply means of the fuel cell system of this invention. It is a figure explaining the structure of the other example of the oxidizing agent gas supply means of the fuel cell system of this invention. It is a figure explaining the structure of the other example of the oxidizing agent gas supply means of the fuel cell system of this invention. It is a figure explaining the structure of the cell of a fuel cell, and the mechanism at the time of electric power generation. It is a flowchart explaining an example of the driving | running method of the conventional fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Stack, 12 Drainage maintenance agent storage tank, 14 Flow rate controller, 16, 16a, 16b, 16c Oxidant gas supply means, 18 monitor, 20 collection means.

Claims (7)

In a fuel cell system having a fuel cell formed by laminating a cell composed of a joined body having a fuel electrode and an air electrode on an electrolyte membrane, and a pair of separators sandwiching the joined body,
A fuel cell system comprising a drainage maintenance agent supply means for supplying a drainage maintenance agent for maintaining drainage in the cell to the fuel cell. A fuel cell formed by laminating a cell composed of a joined body having a fuel electrode and an air electrode on an electrolyte membrane, and a pair of separators sandwiching the joined body;
In a fuel cell system comprising a reaction gas supply means for supplying a reaction gas to the fuel cell,
The fuel cell system further comprises waste water maintenance agent supply means for supplying a waste water maintenance agent for maintaining drainage in the cell to the reaction gas supplied by the reaction gas supply means. The fuel cell system according to claim 1 or 2,
And a monitor for monitoring the usage state of the fuel cell,
A fuel cell system, wherein a drainage maintenance agent is supplied to the fuel cell from the drainage maintenance agent supply means according to a use state of the fuel cell obtained from the monitor. In the fuel cell system according to any one of claims 1 to 3,
Furthermore, an exhaust gas passage for circulating exhaust gas discharged from the fuel cell;
A fuel cell system, comprising: a recovery means provided on the exhaust gas flow path for recovering the waste water maintenance agent. In the fuel cell system according to any one of claims 1 to 4,
The fuel cell system, wherein the drainage maintenance agent is a surface tension reducing agent that reduces the surface tension of the reaction water generated in the cell. The fuel cell system according to claim 5, wherein
The fuel cell system, wherein the surface tension reducing agent is at least one agent selected from the group consisting of alcohols and surfactants. The fuel cell system according to any one of claims 1 to 6, wherein
The drainage maintenance supply means supplies the drainage maintenance agent to the cathode side having the air electrode.

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