JP5286741B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system provided with a flow passage through which pure water for humidifying a reaction gas through a porous separator and cooling the system with latent heat of vaporization flows.

  Generally, in some polymer electrolyte fuel cells, depending on the wet state of the solid polymer electrolyte membrane used, there are those that do not exhibit sufficient ionic conductivity. Therefore, solid fuel can be obtained by humidifying fuel gas or oxidant gas. The wet state of the molecular electrolyte membrane is maintained.

  There are two types of humidification methods for fuel gas and oxidant gas: an external humidification method in which humidification is performed by a humidifier provided outside the fuel cell stack, and an internal humidification method in which humidification is performed inside the fuel cell stack.

  In the internal humidification method, porous separators (porous separators) that can soak moisture are used, pure water is supplied to these porous separators, and moisture soaked in porous separators, fuel gas, and oxidant gas Are in contact with each other to humidify at least one reaction gas of the fuel gas and the oxidant gas. Further, in the internal humidification system, there is a fuel cell system that cools the fuel cell by latent heat of vaporization accompanying evaporation of moisture soaked in a porous separator.

As a conventional fuel cell provided with such a porous separator, for example, those described in Patent Document 1 and Patent Document 2 shown below are known.
Japanese Patent Laid-Open No. 6-068884 JP-A-8-250130

  The porous separator employed in the above conventional fuel cell has a feature that the reaction gas is difficult to permeate when sufficiently wetted with moisture, but does not contain a sufficient amount of moisture when dried. In some cases, the reaction gas may permeate the porous separator. However, when the reaction gas leaks from the normal path through the porous separator, there is a problem that this cannot be detected.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a fuel cell system capable of detecting leakage of a reactive gas through a porous separator.

In order to achieve the above object, a means for solving the problems of the present invention is to generate power by an electrochemical reaction between a fuel gas supplied by a fuel gas supply means and an oxidant gas supplied by an oxidant gas supply means. And pure water that humidifies at least one of the fuel gas and the oxidant gas that circulates through the fuel cell via a porous separator, and that latently cools the fuel cell by vaporization passes through the fuel cell. In a fuel cell system including a pure water flow path that includes and circulates, a detection unit that detects that at least one of a fuel gas and an oxidant gas leaks into the pure water flow path through the porous separator. wherein the sensing means includes flow sensing means upstream of the provided pure water passage of the fuel cell, to close the downstream side the pure water flow path of the fuel cell A blocking means for closing the pure water flow path on the downstream side of the fuel cell, and detecting leakage when the flow rate detecting means detects a reverse flow of pure water in the pure water flow path on the upstream side of the fuel cell; characterized in that it.

  According to the present invention, it is possible to detect that at least one of the fuel gas and the oxidant gas leaks into the pure water flow path through the porous separator.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  Before describing each of the first to ninth embodiments of the present invention, the basic configuration and the basic operation common to each embodiment will be described with reference to the basic configuration diagram shown in FIG. 1 and the flowchart showing the basic operation in FIG. Then, the characteristic configuration and operation of each embodiment will be described.

  In FIG. 1, the fuel cell system of the present invention common to each embodiment includes a fuel cell stack 101 that generates power by an electrochemical reaction between a fuel gas and an oxidant gas. In this fuel cell stack 101, an anode electrode 103 and a cathode electrode 104 are opposed to each other with a MEA (Membrane Electrode Assembly) 102 including a solid polymer electrolyte membrane interposed therebetween. A plurality of fuel cell structures in which a porous separator (porous separator) 105 is disposed outside are stacked (not shown).

  Such a fuel cell stack 101 is provided with a fuel gas flow path (not shown) for supplying a fuel gas to the anode electrode 103 side, and an oxidant gas flow path (see FIG. 5) for supplying an oxidant gas to the cathode electrode 104 side. Not shown).

  In the following description, fuel gas and oxidant gas are collectively referred to as reaction gas. In the following embodiments, the fuel cell stack 101 supplies hydrogen gas to the anode electrode 103 as a fuel gas for generating a power generation reaction, and supplies oxygen containing oxygen as an oxidant gas to the cathode electrode 104. Will be described.

  The fuel cell stack 101 separates each fuel cell by a porous separator 105 to which humidified pure water for humidifying the solid polymer electrolyte membrane is supplied. The porous separator 105 has one surface facing the electrode side of the adjacent fuel battery cell, forming a reaction gas flow path corresponding to each electrode, and a pure water flow in which pure water for humidification circulates on the other surface. A path 106 is provided. Thereby, the fuel cell stack 101 is supplied with the pure water for humidification to the pure water flow path 106, so that the porous surface of the porous separator 105 is filled with the pure water for humidification, and the humidifying pure water soaked into the porous separator 105 is obtained. The reaction gas supplied to the fuel cell stack 101 is humidified with pure water, and the solid polymer electrolyte membrane is humidified with the humidified reaction gas.

  In such a fuel cell system, when generating electricity in the fuel cell stack 101, humidified hydrogen gas is supplied to the anode electrode 103, and humidified air is supplied to the cathode electrode 104, so that the solid polymer electrolyte membrane in the fuel cell stack 101 is supplied. This is an internal humidification type vaporization latent heat cooling type fuel cell system that supplies pure water for humidification that humidifies and cools the fuel cell stack 101 by vaporization latent heat. In this fuel cell system, the operation is controlled and managed by a controller 107 described later.

  The air supplied to the fuel cell stack 101 is pressurized by the air supply pump 108 and humidified by, for example, an air humidifier (not shown), and then the cathode of the fuel cell stack 101 via the air circulation pipe L1. Supplied to the pole 104. At this time, the controller 107 controls the number of rotations of a pump driving motor (not shown) connected to the air supply pump 108, and the air pressure regulating valve 109 provided in the air circulation pipe L1 on the air discharge side. The flow rate of air supplied to the cathode electrode 104 and the air pressure are adjusted by controlling the degree of opening.

  The hydrogen gas supplied to the fuel cell stack 101 is supplied from the state stored in the hydrogen tank 110 to the anode electrode 103 of the fuel cell stack 101 through the hydrogen pressure regulating valve 111 and the hydrogen circulation pipe L2 in order. The unused hydrogen discharged from the anode electrode 103 to the hydrogen circulation pipe L2 on the hydrogen discharge side is normally circulated again to the anode electrode 103 side by the hydrogen circulation pump 112 provided in the circulation path, for example, and re-supplied.

  Further, in order to accumulate nitrogen that has permeated from the cathode electrode 104 to the anode electrode 103 through the solid polymer electrolyte membrane in the circulation path, for example, a purge valve 113 that purges the accumulated nitrogen out of the circulation path is provided. At this time, the controller 107 controls the opening degree of the hydrogen pressure regulating valve 111 to adjust the hydrogen pressure supplied to the anode electrode 103, and controls the rotation speed of the motor connected to the hydrogen circulation pump 112 and the opening degree of the purge valve 113. adjust.

  The humidified pure water supplied to the fuel cell stack 101 is stored in a pure water tank 114 that is installed above the fuel cell stack 101 and opened to the atmosphere with respect to the height direction in the installation environment of the fuel cell system. From this state, the fuel cell stack 101 is supplied via the pure water circulation pipe L3. The pure water flow pipe L3 on the discharge side (downstream side) of the pure water flow path 106 is provided with an opening / closing valve 115. For example, the pure water tank 114 is closed by an amount that is closed during normal operation and evaporated inside the fuel cell stack 101. From the pure water is supplied to the fuel cell stack 101.

  The on-off valve 115 is used for filling the deionized water distribution pipe L3 in the initial state and degassing, as well as for filling the deionized water distribution pipe L3 through the porous separator 105 with the water after the reaction gas has permeated. The valve is opened when degassing and closed during normal power generation.

  The pure water supplied to the fuel cell stack 101 fills the porous surface of the porous separator 105 with moisture to humidify the reaction gas, and the heat generated in the fuel cell stack 101 is vaporized by latent heat of vaporization together with unreacted gas. Discharge outside the fuel cell system.

  Further, in order to recover the water vapor discharged outside the system, a water recovery device including, for example, a condenser 116 and a gas-liquid separator 117 is provided on the upstream side of the air pressure regulating valve 109 in the air circulation pipe L1. The water balance can be established by feeding the pure water collected by the apparatus to the pure water tank 114 via the pure water collection pipe L4. The water supply from the water recovery device to the pure water tank 114 is performed by, for example, a pure water pump (not shown) provided in the pure water recovery pipe L4.

  In the above basic configuration, as described above, a configuration in which auxiliary equipment such as a pump is not used when pure water is supplied from the pure water tank 114 to the fuel cell stack 101 is employed. A configuration may be adopted in which a pure water supply pump is provided in the pure water circulation pipe L3 between the stacks 101 and pure water is supplied from the pure water tank 114 to the fuel cell stack 101 by this pump.

  The controller 107 functions as a control center for controlling the operation of the system, and includes, for example, a microcomputer having resources such as a CPU, a storage device, and an input / output device necessary for a computer that controls various operation processes based on a program. It is realized by. The controller 107 reads signals from sensors that collect information necessary for operation of the system, such as sensors described in each embodiment described later and other pressures, temperatures, concentrations, voltages, and currents that cannot be obtained by these sensors. Based on the read various signals and the control logic (program) held in the inside in advance, a command is sent to the components requiring control of the system including the pumps and valves, and the porous separator 105 described below is provided. All operations necessary for operation / stop of this system including the operation to detect leakage of reaction gas via the system are managed and controlled.

  Further, the controller 107 repeatedly executes the processing shown in the flowchart of FIG. 2 at a preset period when the system is operating. That is, it is determined whether or not the reaction gas has leaked into the pure water flow path 106 through the porous separator 105 (step S201), and when it is determined that it has leaked, the power generation of the fuel cell stack 101 is stopped. The system operation is stopped (step S202), and a series of processing is controlled. On the other hand, if it is determined that there is no leakage, the normal operation is continued and the process is terminated.

  In each embodiment described below, a characteristic configuration of each embodiment further added to the configuration shown in FIG. 1 and a leak determination technique shown in step S201 of FIG. 2 will be described.

  FIG. 3 is a diagram showing the configuration of the fuel cell system according to Embodiment 1 of the present invention. In the system of Embodiment 1 shown in FIG. 3, in addition to the basic configuration shown in FIG. 1, the pure water circulation pipe L3 between the fuel cell stack 101 and the pure water tank 114 is connected to the fuel cell from the pure water tank 114. A flow sensor 301 for detecting the flow rate of pure water flowing through the stack 101 is provided.

  In such a configuration, the controller 107 reads the sensor signal detected by the flow sensor 301 as the discrimination process shown in step S201 of FIG. 2, and based on this sensor signal, the fuel cell stack 101 from the pure water tank 114. It is determined whether or not the flow rate of pure water flowing through the water is not more than a predetermined flow rate set in advance. Here, the predetermined flow rate is a value that can be estimated as pure water flowing backward from the fuel cell stack 101 side to the pure water tank 114 side, and may be, for example, 0 L / min or less, or a current load (power generation amount). ) May be experimentally obtained in advance, and a predetermined flow rate value may be set based on the value.

  As a result of the determination, if it is determined that the flow rate is equal to or lower than the predetermined flow rate, it is estimated that pure water is flowing backward, and the reaction gas permeates into the pure water flow path 106 through the porous separator 105 and leaks. Judge that it is.

  As described above, in the first embodiment, it is possible to detect the leakage of the reaction gas with a simple configuration in which the flow rate sensor 301 is added to the configuration provided in the normal fuel cell system.

  In addition, when the leakage of the reaction gas is detected, the operation of the fuel cell system is stopped to avoid the deterioration of the fuel consumption performance and the power generation performance and the cooling performance of the vaporization latent heat cooling fuel cell system. It becomes possible, and damage to the fuel cell stack 101 that may be caused when the operation is continued in a state where the performance is deteriorated can be avoided.

  FIG. 4 is a diagram showing a configuration of a fuel cell system according to Embodiment 2 of the present invention. The system of the second embodiment shown in FIG. 4 includes a cell voltage sensor 401 that monitors the cell voltage of each cell of the fuel cell stack 101 in addition to the configuration of the first embodiment shown in FIG.

  In such a configuration, the controller 107 first reads the sensor signals detected by the flow rate sensor 301 and the cell voltage sensor 401 as the discrimination processing shown in step S201 of FIG. 2, and determines the flow rate obtained by the flow rate sensor 301. Then, it is determined whether or not the pure water evaporation amount of the fuel cell stack 101 estimated based on the sensor signal of the cell voltage sensor 401 is smaller. As a result of the discrimination, if it is discriminated that it is small, it is estimated that the pure water is flowing backward. Thereby, it is estimated that the reaction gas permeates the pure water flow path 106 through the porous separator 105, and the leakage of the reaction gas can be detected.

  Here, a method for estimating the pure water evaporation amount of the fuel cell stack 101 based on the cell voltage obtained by the cell voltage sensor 401 will be described.

  The current-voltage characteristic (IV curve) in the fuel cell stack is expressed as shown in FIG. 5, for example. Based on this characteristic curve, when the fuel cell stack is generating electric power, the heat generation amount (W) of the fuel cell stack is expressed as follows.

(Equation 1)
Heat value of fuel cell stack = (Vt−V) I
Here, Vt is a theoretical electromotive force.

  On the other hand, when the external heat dissipation of the fuel cell stack 101 is ignored, the calorific value generated by the power generation of the fuel cell stack 101 is used for the evaporation of pure water supplied to the fuel cell stack 101. When the phase of water changes, that is, when the phase of water changes from a liquid to a gas, an amount of heat is required as shown below.

H ₂ O (liquid) → H ₂ O (gas) +44000 (J / mol)
Therefore, assuming that the calorific value of the fuel cell stack 101 is all used for the evaporation heat of pure water supplied to the fuel cell stack 101, the evaporation amount (mol / sec) of pure water is expressed as follows. Is done.

(Equation 2)
Evaporation amount of pure water (mol / sec) = calorific value of fuel cell stack (W) / 44000 (J / mol)
In the above method, for ease of understanding, it has been described that all the calorific value of the fuel cell stack 101 is used as the calorific value when pure water evaporates, but it corresponds to the voltage of the fuel cell stack 101. Evaporation amount of pure water is experimentally obtained in advance, the result is tabulated and stored in the storage means of the controller 107, and the pure water is evaporated by referring to the above table based on the measured value obtained by the cell voltage sensor 401. The amount may be calculated.

  In addition, the temperature of the surface of the fuel cell stack 101 and the temperature of the atmosphere are measured so that the external heat dissipation amount of the fuel cell stack 101 can be taken into account, and the evaporation amount of pure water is corrected by the external heat dissipation amount estimated from the difference between the two temperatures. You may make it do. By adopting such a method, it is possible to improve the estimation accuracy of the pure water evaporation amount.

  In the second embodiment, the cell voltage is monitored when the pure water evaporation amount is estimated. However, the pure water evaporation amount is monitored even if the total voltage of the fuel cell stack 101 is monitored instead of monitoring the cell voltage. Can be estimated.

  As described above, in the second embodiment, the flow direction of pure water is estimated based on the relationship between the evaporation amount of pure water corresponding to the heat generation amount of the fuel cell stack 101 and the flow rate obtained by the flow sensor 301. Thus, it is possible to detect a minute backflow of pure water. Thereby, the detection accuracy and responsiveness when the reaction gas leaks can be further improved as compared with the first embodiment.

  FIG. 6 is a diagram showing a configuration of a fuel cell system according to Embodiment 3 of the present invention. In the system of the third embodiment shown in FIG. 6, in addition to the basic configuration shown in FIG. 1, the pure water circulation pipe L3 between the fuel cell stack 101 and the on-off valve 115 on the pure water discharge side of the fuel cell stack 101. Is provided with a pressure sensor 601.

  In such a configuration, the controller 107 reads the sensor signal detected by the pressure sensor 601 as the discrimination processing shown in step S201 of FIG. 2, and the pressure obtained by the pressure sensor 601 based on this sensor signal is read. It is determined whether or not the pressure is equal to or higher than a predetermined pressure value set in advance. Here, the predetermined pressure value may be set as a value obtained experimentally by the pressure when the reaction gas leaks, or a value obtained by adding a margin to the maximum value of the pure water pressure range when designing the system. May be set as

  As a result of the determination, if it is determined that the pressure value is equal to or higher than the predetermined pressure value, the reaction gas flows into the pure water circulation pipe L3 on the pure water discharge side via the porous separator 105, and the inside of the pure water circulation pipe L3. It is estimated that the pressure of the gas has increased, and it is determined that the reaction gas has leaked.

  As described above, in the third embodiment, the same effect as in the first embodiment can be obtained.

  FIG. 7 is a diagram showing a configuration of a fuel cell system according to Embodiment 4 of the present invention. In the system of the fourth embodiment shown in FIG. 7, in addition to the basic configuration shown in FIG. 1, the pressure sensor 701 and the pressure sensor 701 are connected to the pure water circulation pipe L3 between the fuel cell stack 101 and the pure water tank 114. A reverse valve 702 is provided on the upstream side of the sensor 701.

  In such a configuration, the controller 107 reads the sensor signal detected by the pressure sensor 701 as the discrimination processing shown in step S201 of FIG. 2, and the pressure obtained by the pressure sensor 701 based on this sensor signal is read. It is determined whether or not the pressure is equal to or higher than a predetermined pressure value set in advance. Here, the predetermined pressure value may be set as a value obtained experimentally by the pressure when the reaction gas leaks, or a value obtained by adding a margin to the maximum value of the pure water pressure range when designing the system. May be set as

  As a result of the determination, if it is determined that the pressure value is equal to or higher than the predetermined pressure value, the reaction gas flows out to the pure water circulation pipe L3 on the pure water inflow side via the porous separator 105, and downstream of the reverse valve 702. It is estimated that the pressure in the pure water circulation pipe L3 has increased, and it is determined that the reaction gas has leaked.

  As described above, in the fourth embodiment, the same effect as in the first embodiment can be obtained. Further, it is possible to give a degree of freedom to the arrangement position of the pressure sensor functioning as the pressure estimating means.

  FIG. 8 is a diagram showing a configuration of a fuel cell system according to Embodiment 5 of the present invention. In the system of the fifth embodiment shown in FIG. 8, in addition to the basic configuration shown in FIG. 1, the pressure sensor 801 is connected to the pure water circulation pipe L3 on the pure water inflow side between the fuel cell stack 101 and the pure water tank 114. And a pressure sensor 802 is provided in the pure water circulation pipe L3 between the fuel cell stack 101 and the on-off valve 115 on the pure water discharge side.

  In such a configuration, the controller 107 reads the sensor signals detected by both the pressure sensors 801 and 802 as the discrimination processing shown in step S201 of FIG. 2, and the pressure sensor 801 based on these sensor signals. A pressure difference (differential pressure) between the obtained pressure and the pressure obtained by the pressure sensor 802 is calculated, and it is determined whether or not the differential pressure is equal to or less than a predetermined differential pressure value set in advance. Here, the predetermined differential pressure value may be set as a value obtained experimentally by calculating the differential pressure when the reactant gas leaks, or a margin is added to the minimum value of the pure water differential pressure range when designing the system. It may be set as an added value.

  If the power generation output and power generation efficiency of the fuel cell stack 101 are constant and the heat generation amount is constant, the evaporation amount of pure water in the fuel cell stack 101 is constant, and the supply amount of pure water supplied to the fuel cell stack 101 is It becomes constant. If the flow rate of pure water is constant, the pressure difference (differential pressure) between the pressure of pure water flowing into the fuel cell stack 101 and the pressure on the discharge side is constant as shown in FIG. However, when the reaction gas leaks into the pure water flow path 106, the flow rate of pure water flowing through the pure water distribution pipe L3 decreases. As a result, the pressure difference (differential pressure) between the pressure on the pure water inflow side and the pressure on the discharge side of the fuel cell stack 101 decreases with the passage of time as shown in FIG.

  Therefore, if it is determined that the pressure difference is equal to or lower than the predetermined differential pressure value as a result of the determination, it is assumed that the reaction gas flows out to the pure water circulation pipe L3 through the porous separator 105, and the reaction gas is Judge as leaking.

  As described above, in the fifth embodiment, the same effect as in the first embodiment can be obtained. Further, by monitoring the differential pressure between the upstream side and the downstream side with respect to the fuel cell stack 101, compared to the case where a pressure sensor is provided on either the upstream side or the downstream side with respect to the fuel cell stack 101. It is possible to avoid the influence of pressure vibration and the like. Thereby, false detection is suppressed and detection accuracy can be improved.

  The same effect can be obtained by combining a pressure sensor and a differential pressure sensor.

  FIG. 10 is a diagram showing the configuration of the fuel cell system according to Example 6 of the present invention. The system of the sixth embodiment shown in FIG. 10 is characterized by adopting a combination of the configuration of the first embodiment shown in FIG. 3 and the configuration of the fifth embodiment shown in FIG. That is, in addition to the basic configuration shown in FIG. 1, the flow sensor 301 of the first embodiment and the pressure sensors 801 and 802 of the fifth embodiment are provided.

  In such a configuration, the controller 107 reads the sensor signals detected by the flow sensor 301 and the pressure sensors 801 and 802 as the discrimination processing shown in step S201 of FIG. Calculate the differential pressure. Subsequently, an estimated differential pressure value corresponding to the flow rate obtained by the flow rate sensor 301 was obtained with reference to a table showing the relationship between the flow rate and the differential pressure as shown in FIG. 11, and calculated from the measured values of both pressure sensors. It is determined whether or not the differential pressure is less than or equal to the estimated differential pressure value. Here, the above table is prepared by previously obtaining the relationship between the flow rate and the differential pressure by experiments or the like and storing it in the storage means of the controller 107.

  As a result of the determination, if it is determined that the value is equal to or less than the estimated value, it is determined that the reaction gas has permeated and leaked through the pure water channel 106 via the porous separator 105. For example, as shown in FIG. 12, when the reaction gas locally leaks on the flow path surface of the porous separator 105, the flow rate of the pure water for humidification does not change and is lower than the fuel cell stack 101. The pressure on the side increases, which may reduce the differential pressure. By estimating that such a phenomenon has occurred by the above-described discrimination processing, it is possible to detect leakage of the reaction gas.

  Thus, in Example 6 described above, it is possible to detect local leakage by determining leakage of the reaction gas based on the flow rate and the differential pressure. In addition, it is possible to ignore the influence of pressure fluctuations due to fluctuations in flow rate, so that erroneous detection can be suppressed and detection accuracy can be improved.

  FIG. 13 is a diagram showing the configuration of the fuel cell system according to Example 7 of the present invention. In the system of the seventh embodiment shown in FIG. 13, in addition to the basic configuration shown in FIG. 1, the temperature sensor 1301 is provided on the reaction gas discharge side pipe in the fuel cell stack 101, that is, on the air discharge side in the air circulation pipe L1. And a temperature sensor 1302 is provided on the hydrogen discharge side of the hydrogen circulation pipe L2.

  In such a configuration, the controller 107 reads the sensor signals detected by the temperature sensors 1301 and 1302 and obtains the temperature sensors 1301 and 1302 based on the sensor signals as the discrimination processing shown in step S201 of FIG. It is determined whether at least one of the set temperatures is equal to or higher than a predetermined temperature value set in advance. Here, the predetermined temperature value may be set as a value obtained experimentally from the temperature at which the reactant gas leaks, or a margin is provided for the maximum value of the temperature range of the fuel cell stack 101 when designing the system. It may be set as an added value.

  As a result of the determination, if it is determined that the temperature is equal to or higher than the predetermined temperature value, the reaction gas permeates through the porous separator 105 to the pure water flow path 106 side, so that the evaporation amount of pure water decreases, and cooling by evaporation (Evaporation latent heat amount) is insufficient, and the reaction gas receives the amount of heat. As a result, the exhaust gas temperature of the reaction gas rises, and the reaction gas temperature accompanying the permeation of the reaction gas and the temperature of the fuel cell stack 101 main body rises. It can be estimated that Thereby, it is determined that the reaction gas leaks into the pure water flow path 106 through the porous separator 105.

  As described above, in the seventh embodiment, the same effect as in the first embodiment can be obtained.

  FIG. 14 is a diagram showing the configuration of the fuel cell system according to Example 8 of the present invention. In the system of Example 8 shown in FIG. 14, in addition to the basic configuration shown in FIG. 1, a temperature sensor 1401 is provided in the pure water circulation pipe L3 between the fuel cell stack 101 and the pure water tank 114.

  In such a configuration, the controller 107 reads the sensor signal detected by the temperature sensor 1401 as the discrimination process shown in step S201 of FIG. 2, and the temperature obtained by the temperature sensor 1401 based on this sensor signal is read. It is determined whether or not the temperature is equal to or higher than a predetermined temperature value set in advance. Here, the predetermined temperature value may be set as a value obtained by experimentally determining the temperature of the pure water for humidification when the reaction gas leaks, or the maximum temperature range of the pure water for humidification when the system is designed. The value may be set as a value obtained by adding a margin. Further, the temperature on the supply side of the pure water for humidification such as the pure water tank 114 may be measured, and a predetermined temperature value may be set based on the temperature.

  As a result of the determination, if it is determined that the temperature is equal to or higher than the predetermined temperature value, the reaction gas permeates the pure water flow path 106 through the porous separator 105 and leaks into the pure water flow path pipe L3. It can be presumed that the amount of heat generated in 101 increases, and the humidified pure water heated thereby flows backward to the pure water tank 114 side, and the temperature of the humidified pure water is rising. Thereby, it is determined that the reaction gas leaks into the pure water flow path 106 through the porous separator 105.

  As described above, in the eighth embodiment, the same effect as in the first embodiment can be obtained.

  FIG. 15 is a diagram showing the configuration of the fuel cell system according to Example 9 of the present invention. In the system of the ninth embodiment shown in FIG. 15, in addition to the basic configuration shown in FIG. 1, the hydrogen concentration sensor 1501 and the oxygen concentration are provided in the pure water circulation pipe L3 between the fuel cell stack 101 and the pure water tank 114. A sensor 1502 is provided. This may be provided in the pure water tank 114.

  In such a configuration, the controller 107 reads the sensor signals detected by the hydrogen concentration sensor 1501 and the oxygen concentration sensor 1502 as the discrimination processing shown in step S201 of FIG. It is determined whether at least one of the oxygen concentrations is equal to or higher than a predetermined concentration value set in advance. Here, the predetermined concentration value may be set as a value obtained by experimentally determining the hydrogen concentration and the oxygen concentration in the pure water circulation pipe L3 when the reaction gas leaks, or pure water when the system is designed. You may set as a value which added the margin to the maximum value of the hydrogen concentration and oxygen concentration range in the distribution pipe L3.

  As a result of the determination, if it is determined that the concentration is equal to or higher than the predetermined concentration value, the reaction gas permeates the pure water flow path 106 through the porous separator 105 and leaks to the pure water flow path pipe L3, so that the fuel cell It can be estimated that the hydrogen concentration and / or the oxygen concentration in the pure water distribution pipe L3 on the upstream side of the stack 101 are increased. Thereby, it is determined that the reaction gas leaks into the pure water flow path 106 through the porous separator 105.

  As described above, in the ninth embodiment, the same effect as in the first embodiment can be obtained.

  In addition, you may make it implement the said Examples 1-9 in combination suitably, In that case, it can anticipate improving the detection precision and responsiveness of a reactive gas.

It is a figure which shows the basic composition of the fuel cell system which concerns on Examples 1-9 of this invention. It is a flowchart which shows the procedure of the basic operation process which concerns on Examples 1-9 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 1 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 2 of this invention. It is a figure which shows the current-voltage characteristic of the fuel cell stack which concerns on Example 2 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 3 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 4 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 5 of this invention. It is a figure which shows the change of the fuel cell back-and-front differential pressure | voltage of the pure water path | route before and after the leakage of the reactive gas which concerns on Example 5 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 6 of this invention. It is a figure which shows the relationship between the pure water flow which concerns on Example 6 of this invention, and the fuel cell front-back differential pressure | voltage in a pure water path | route. It is a figure which shows the leak generation | occurrence | production point of the reactive gas in the porous separator which concerns on Example 6 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 7 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 8 of this invention. It is a figure which shows the structure of the fuel cell system which concerns on Example 9 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Fuel cell stack 103 ... Anode electrode 104 ... Cathode electrode 105 ... Porous separator 106 ... Pure water flow path 107 ... Controller 108 ... Air supply pump 109 ... Air pressure regulating valve 110 ... Hydrogen tank 111 ... Hydrogen pressure regulating valve 112 ... Hydrogen circulation Pump 113 ... Purge valve 114 ... Pure water tank 115 ... Open / close valve 116 ... Condenser 117 ... Gas-liquid separator 301 ... Flow sensor 401 ... Cell voltage sensor 601,701,801,802 ... Pressure sensor 702 ... Reverse support valve 1301,1302 , 1401 ... Temperature sensor 1501 ... Hydrogen concentration sensor 1502 ... Oxygen concentration sensor L1 ... Air flow pipe L2 ... Hydrogen flow pipe L3 ... Pure water flow pipe L3 ... Pure water flow pipe L4 ... Pure water recovery pipe

Claims (9)

A fuel cell that generates electricity by an electrochemical reaction between a fuel gas supplied by the fuel gas supply means and an oxidant gas supplied by the oxidant gas supply means;
Pure water that humidifies at least one of the fuel gas and the oxidant gas that circulates through the fuel cell via the porous separator and that latently cools the fuel cell by vaporization includes the inside of the fuel cell. In a fuel cell system with a water flow path,
A detecting means for detecting that at least one of fuel gas and oxidant gas leaks into the pure water flow path through the porous separator ;
The detection means includes flow rate detection means provided in the pure water flow path upstream of the fuel cell, and blocking means for closing the pure water flow path downstream of the fuel cell,
The pure water flow path on the downstream side of the fuel cell is closed, and leakage is detected when the flow rate detection means detects a reverse flow of pure water in the pure water flow path on the upstream side of the fuel cell. A fuel cell system. The detection means includes voltage detection means for detecting the voltage of the fuel cell;
Flow rate estimation means for estimating the flow rate of pure water supplied to the fuel cell based on the voltage detected by the voltage detection means ;
2. The fuel cell system according to claim 1, wherein leakage is detected when a difference occurs between the flow rate estimated by the flow rate estimation unit and the flow rate detected by the flow rate detection unit . It said sensing means includes a pressure sensing hand stage provided in the pure water flow path downstream of the fuel cell,
Claim 1, wherein the fuel closes the pure water flow path downstream of the battery, characterized in that the pressure of the pure water that has been detected by the pressure detecting means detects leakage in the case of more than a predetermined value set in advance The fuel cell system described in 1. The detecting means includes pressure detecting means provided in the pure water flow channel upstream of the fuel cell;
A reverse support valve provided in the pure water flow path upstream of the pressure detection means ;
2. The pure water flow path on the downstream side of the fuel cell is closed, and leakage is detected when the pressure of pure water detected by the pressure detecting means is equal to or higher than a predetermined value. The fuel cell system described in 1. It said sensing means includes a differential pressure detection means to detect the pressure difference between pure water of the pure water and the downstream side of the upstream side of the fuel cell,
Closing the net water flow path downstream of the fuel cell, to claim 1, characterized in that the differential pressure detected by the differential pressure detecting means detects leakage in the case of more than a predetermined value The fuel cell system described. The detecting means detects a differential pressure between pure water on the upstream side and pure water on the downstream side of the fuel cell;
The flow rate of pure water flowing through the pure water flow path upstream of the fuel cell during normal operation in which fuel gas and oxidant gas do not leak into the pure water flow path through the porous separator, and the fuel A differential pressure for calculating a differential pressure corresponding to the flow rate of pure water detected by the flow rate detection means with reference to a table representing the relationship between the differential pressure between pure water on the upstream side and pure water on the downstream side of the battery Having a calculation means,
The pure water flow path on the downstream side of the fuel cell is closed, and leakage is detected when the differential pressure detected by the differential pressure detection means is equal to or less than the differential pressure calculated by the differential pressure calculation means. The fuel cell system according to claim 1. The detection means has a temperature detection means for detecting the temperature of one or both of the fuel gas and the oxidant gas discharged from the fuel cell,
2. The fuel cell system according to claim 1, wherein leakage is detected when the temperature detected by the temperature detection means is equal to or higher than a predetermined value set in advance . The detection means has temperature detection means for detecting the temperature of pure water upstream of the fuel cell,
The pure water flow path on the downstream side of the fuel cell is closed, and leakage is detected when the temperature detected by the temperature detecting means is equal to or higher than a predetermined value set in advance. Fuel cell system. It said detecting means has the fuel upstream of the fuel gas concentration as well as any gas concentration detecting means to detect one or both of the oxidant gas concentration of the pure water channel of the battery,
The pure water flow path on the downstream side of the fuel cell is closed, and leakage is detected when the gas concentration detected by the gas concentration detecting means is equal to or higher than a predetermined value set in advance. The fuel cell system described in 1.

Images