JP2006331822A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system which can prevent moisture in a fuel gas from being frozen. <P>SOLUTION: The fuel cell system (100) is provided with a fuel cell (20) in which electric power is generated by the fuel gas containing hydrogen and an oxidant gas containing oxygen, and a heat exchange means (30, 106) for heating the fuel gas. The heat exchange means (30, 106) is characterized by heating the fuel gas by a fuel exhaust gas and an oxidizer exhaust gas exhausted from the fuel cell (20). In this case, the fuel gas is sufficiently heated in the heat exchange means (30, 106) by both of the fuel exhaust gas and the oxidizer exhaust gas. By the above, the moisture in the fuel gas is prevented from being frozen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. This fuel cell has been developed widely as a future energy supply system because it is environmentally friendly and can realize high energy efficiency.

  When the fuel cell is used under a low temperature condition or the like, it is necessary to prevent freezing of water in the system piping. For example, a fuel cell stack gas supply device including a pipe having a double pipe structure through which exhaust gas passes around a supply gas pipe is disclosed (for example, see Patent Document 1). According to this technique, the supply gas (fuel gas) can be preheated using the heat of the exhaust gas of the fuel cell.

JP 2000-306593 A

  However, in the technique of Patent Document 1, there is only one type of fluid that exchanges heat with the fluid in the supply pipe. Therefore, in a low temperature fuel cell such as a solid polymer fuel cell, the fluid in the supply pipe cannot be sufficiently heated under a low temperature condition. As a result, the fuel cell system may not be prevented from freezing.

  An object of this invention is to provide the fuel cell system which can prevent the water | moisture content in fuel gas freezing.

  A fuel cell system according to the present invention includes a fuel cell that generates power using a hydrogen-containing fuel gas and an oxygen-containing oxidant gas, and a heat exchange unit that heats the fuel gas. The fuel gas is heated by the fuel exhaust gas and the oxidant exhaust gas discharged from the fuel. In the fuel cell system according to the present invention, the fuel gas is sufficiently heated by the gas of both the fuel exhaust gas and the oxidant exhaust gas in the heat exchange means. Thereby, freezing of moisture in the fuel gas is prevented.

  The heat exchange means further includes an exhaust gas treatment means for treating the fuel exhaust gas and the oxidant exhaust gas, and a fuel gas supply pipe for supplying the fuel gas to the fuel cell. The fuel gas supply pipe passes through the exhaust gas treatment means. May be. In this case, the fuel gas supply pipe is sufficiently heated by both the fuel exhaust gas and the oxidant exhaust gas. Thereby, the fuel gas is also sufficiently heated. As a result, water in the fuel gas is prevented from freezing. Further, since the fuel gas is heated using the exhaust gas treatment means, it is not necessary to newly provide a heating means for heating the fuel gas. Thereby, the fuel cell system according to the present invention can be reduced in size.

  The heat exchanging means further includes a fuel exhaust gas exhaust pipe through which the fuel exhaust gas flows, and the fuel exhaust gas flowing through the fuel exhaust gas exhaust pipe contacts the outer wall of the fuel gas supply pipe between the exhaust gas processing means and the fuel cell. Good. In this case, heat exchange between the fuel exhaust gas and the fuel gas is efficiently performed through the outer wall of the fuel gas supply pipe. Thereby, the fuel gas is sufficiently heated.

  The fuel gas supply pipe may pass through the fuel exhaust gas discharge pipe. In this case, the fuel gas supply pipe is prevented from coming into direct contact with the outside air. Thereby, fuel gas can be heated efficiently.

  The fuel gas supply pipe may include a relief valve in the exhaust gas processing means. In this case, an excessive increase in the gas pressure in the fuel gas supply pipe can be prevented. Thereby, rupture, breakage, etc. of the fuel gas supply pipe can be prevented. Further, the fuel gas discharged from the relief valve is discharged into the exhaust gas processing means. Thereby, it is possible to prevent the fuel gas from being discharged directly to the atmosphere. Furthermore, since the relief valve is provided in the exhaust gas treatment means, it is possible to reduce leakage of the operation sound of the relief valve to the outside. Further, the exhaust gas treatment means may be a diluter that dilutes the exhaust gas.

  According to the present invention, the fuel gas can be sufficiently heated by both the fuel exhaust gas and the oxidant exhaust gas. Thereby, freezing of moisture in the fuel gas is prevented.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic diagram showing an overall configuration of a fuel cell system 100 according to a first embodiment of the present invention. The configuration of the fuel cell system 100 will be described with reference to FIG. As shown in FIG. 1, the fuel cell system 100 includes a humidification module 10, a fuel cell 20, a diluter 30, a muffler 40, and a hydrogen tank 50.

  The humidification module 10 has a function of collecting the moisture in the cathode offgas discharged by the fuel cell 20 and increasing the humidity of the air by supplying the moisture to the air supplied from an air compressor (not shown). The humidification module 10 is connected to an air compressor via a pipe 101, connected to an air inlet 21 of the fuel cell 20 via a pipe 102, and connected to a cathode offgas outlet 22 of the fuel cell 20 via a pipe 103. It is connected to the diluter 30 via 104. The pipe 101 is connected to the pipe 102 in the humidification module 10. The pipe 103 is connected to the pipe 104 in the humidification module 10.

  The fuel cell 20 includes a polymer electrolyte fuel cell, and includes an air inlet 21, a cathode offgas outlet 22, a fuel gas inlet 23, an anode offgas outlet 24, an anode (not shown), and a cathode (not shown). The anode off gas outlet 24 is formed so as to surround the fuel gas inlet 23. The air inlet 21 is connected to the cathode offgas outlet 22 via the cathode. The fuel gas inlet 23 is connected to the anode offgas outlet 24 via the anode. The anode off gas outlet 24 is connected to the diluter 30 via a pipe 107. Details will be described later.

  The diluter 30 has a function of diluting the anode off-gas and the cathode off-gas discharged by the fuel cell 20 and discharging them to the outside. The diluter 30 is connected to the muffler 40 via a pipe 105. The muffler 40 communicates with the outside. The hydrogen tank 50 is a tank for storing liquid hydrogen, and is connected to the fuel gas inlet 23 of the fuel cell 20 via a pipe 106. The pipe 106 passes through the inside of the diluter 30, passes through the inside of the pipe 107, and is connected to the fuel gas inlet 23.

  Next, the operation of the fuel cell system 100 will be described. First, air is supplied to the humidification module 10 via the pipe 101. The humidification module 10 humidifies the supplied air with moisture in the cathode offgas that is discharged from the fuel cell 20 and supplied via the pipe 103. The humidified air is supplied to the cathode of the fuel cell 20 through the pipe 102 and the air inlet 21.

  At the cathode of the fuel cell 20, water is generated and electric power is generated by the reaction between oxygen in the supplied air and hydrogen ions supplied from the anode. The generated water becomes water vapor by the heat generated in the fuel cell 20. Air that has not reacted with water vapor and hydrogen ions generated at the cathode is supplied to the humidification module 10 via the pipe 103 as cathode off-gas. The cathode off gas supplied to the humidification module 10 is supplied to the diluter 30 via the pipe 104.

  In the hydrogen tank 50, the stored liquid hydrogen is heated by a heater (not shown) built in the hydrogen tank 50, whereby hydrogen gas is generated. The generated hydrogen gas is supplied as fuel gas to the anode of the fuel cell 20 through the pipe 106 and the fuel gas inlet 23. The temperature of the hydrogen gas supplied from the hydrogen tank 50 to the pipe 106 may be below freezing point.

  In the diluter 30, the pipe 106 is heated by the cathode offgas supplied from the pipe 104 and the anode offgas supplied from the pipe 107. Thereby, the fuel gas flowing in the pipe 106 is heated. In the pipe 107, the fuel gas flowing in the pipe 106 is heated by the anode off gas flowing in the pipe 107. Thereby, the sufficiently heated fuel gas is supplied to the fuel cell 20. As a result, the water in the fuel gas in the fuel cell 20 is prevented from freezing or condensing. Furthermore, in the fuel cell system 100 according to the present embodiment, the fuel gas is heated by the anode off-gas and the cathode off-gas, so that it is not necessary to newly provide heating means such as a heater for heating the fuel gas. Therefore, the fuel cell system 100 can be reduced in size.

  Hydrogen in the fuel gas supplied to the anode of the fuel cell 20 is converted into hydrogen ions. Hydrogen that has not been converted into hydrogen ions at the anode is supplied to the diluter 30 via the pipe 107 as an anode off gas. The anode off gas is heated by the heat generated in the fuel cell 20. The diluter 30 dilutes the anode off-gas and the cathode off-gas and supplies them to the muffler 40 via the pipe 105. The muffler 40 discharges the supplied anode off-gas and cathode off-gas to the outside.

  Next, details of the fuel cell 20 will be described. FIG. 2 is a diagram for explaining the details of the fuel cell 20. 2A is a schematic diagram of the vicinity of the fuel gas inlet 23 of the fuel cell 20, and FIG. 2B shows details of the fuel gas inlet 23, the anode offgas outlet 24, and the pipes 106 and 107 of the fuel cell 20. It is a typical sectional view to represent.

  As shown in FIG. 2A, the fuel cell 20 further includes an inlet shutoff valve 25, a regulator 26, an end plate 27, a gas-liquid separator 28, and a discharge valve 29. The pipe 106 is connected to the anode inlet (not shown) of the end plate 27 through the inlet shutoff valve 25 and the regulator 26. Further, the anode outlet (not shown) of the end plate 27 is connected to the pipe 107 via a gas-liquid separator 28 and a discharge valve 29.

  The inlet shutoff valve 25 opens and closes the pipe 106. The regulator 26 adjusts the flow rate of the fuel gas flowing through the pipe 106. Thereby, the power generation amount of the fuel cell 20 is adjusted. The end plate 27 functions as a partition plate that partitions the power generation unit and the non-power generation unit in the fuel cell 20.

  The gas-liquid separator 28 performs a gas-liquid separation process on the anode off-gas discharged from the anode outlet. The gas-liquid separator 28 again supplies a part of the gas portion such as unused hydrogen and water vapor in the anode off-gas to the anode inlet of the fuel cell 20, and supplies the remaining portion in the anode off-gas to the discharge valve 29. The discharge valve 29 controls the discharge of the anode off gas to the pipe 107. Note that the inlet shutoff valve 25, the regulator 26, the gas-liquid separator 28, and the discharge valve 29 may be provided outside the fuel cell 20.

  As shown in FIG. 2B, a connecting flange 201 is provided inside the case 200 of the fuel cell 20. The connecting flange 201 has a function of connecting the pipes 106 and 107 and the fuel cell 20. A through hole serving as the fuel gas inlet 23 is formed at the center of the connecting flange 201, and a through hole serving as an anode off-gas outlet is formed outside the fuel gas inlet 23 of the connecting flange 201.

  The pipe 107 has an insulating property. For example, the pipe 107 may be made of an insulating functional resin, and the pipe 107 may have a structure in which a rubber hose is built inside. Moreover, it is preferable that the piping 106 and the piping 107 are flexible pipings, such as a bellows tube and a resin hose. Each connecting portion is sealed with an O-ring (not shown). Therefore, gas leakage and the like can be suppressed.

  As described above, in this embodiment, the pipes 106 and 107 can have a single inlet / outlet pipe. Therefore, the fuel cell 20 can be made compact. As a result, the entire fuel cell system 100 can be made compact. Further, since there is only one inlet / outlet pipe, the pipes 106 and 107 can be easily assembled. Further, since the pipe 107 covers the pipe 106, the pipe 107 functions as a protective material for the pipe 106. Therefore, damage to the pipe 106 can be suppressed.

  In addition, it is possible to prevent the pipe 106 from being cooled by the traveling wind of the vehicle on which the fuel cell system 100 is mounted before the temperature of the fuel cell 20 becomes high. Furthermore, since the pipe 107 covers the pipe 106, it is not necessary to insulate the pipe 106. Therefore, the configuration of the pipe 106 is simplified. As a result, the overall configuration of the fuel cell system 100 is simplified.

  Next, another example of the fuel gas inlet 23, the anode offgas outlet 24, and the end plate 27 shown in FIG. 2 will be described. FIG. 3 is a schematic cross-sectional view of the fuel gas inlet 23a, the anode offgas outlet 24a, and the end plate 27a. As shown in FIG. 3, the end plate 27a has two through holes for piping. Each of the two through holes becomes a fuel gas inlet 23a and an anode off gas 24a.

  In this case, the pipes 106 and 107 are directly connected to the end plate 27a. Therefore, the end plate 27a also functions as a connecting flange. As a result, the fuel cell 20 can be made more compact. Further, since the number of parts is reduced, the number of places where measures for gas leakage are taken is reduced. As a result, the configuration of the fuel cell 20 is simplified. Further, the weight of the connecting flange 201 is reduced.

  Next, a diluter 30a which is another example of the diluter 30 will be described. FIG. 4 is a schematic cross-sectional view of the diluter 30a. As shown in FIG. 4, in the diluter 30 a, the pipe 106 reciprocates inside the pipe 104 and then extends into the pipe 107.

  In this case, the fuel gas flowing in the pipe 106 is sufficiently heated by the cathode off gas flowing in the pipe 104 and then heated by the anode off gas flowing in the pipe 107. Thereby, freezing or condensation of moisture contained in the fuel gas in the fuel cell 20 can be more effectively suppressed. On the other hand, the cathode off gas flowing through the pipe 104 is cooled by the fuel gas flowing through the pipe 106. As a result, water in the cathode off gas condenses and forms water droplets. As a result, white smoke of the gas discharged from the muffler 40 can be suppressed. Note that the number of times the pipe 106 reciprocates in the pipe 104 is not particularly limited. Further, the pipe 106 may reciprocate in the pipe 107.

  Next, pipes 106a and 107a, which are other examples of the pipes 106 and 107, will be described. FIG. 5 is a diagram for explaining the pipes 106a and 107a. FIG. 5A is a plan view of the pipes 106a and 107a, and FIG. 5B is a cross-sectional perspective view of the pipes 106a and 107a.

  As shown in FIGS. 5A and 5B, the pipes 106a and 107a have a structure in which the inside of one pipe is divided into two spaces. In this case, the anode off gas flowing through the pipe 107a comes into contact with the pipe 106a. Thereby, the fuel gas flowing through the pipe 106a is heated by the anode off gas flowing through the pipe 107a. Accordingly, the water in the fuel gas in the fuel cell 20 is suppressed from freezing or condensing. Further, since the pipes 106a and 107a can be formed from a single pipe, the fuel cell system 100 can be saved in space.

  In the present embodiment, a polymer electrolyte fuel cell is used as the fuel cell 20, but any other fuel cell can be applied to the present invention. In the present embodiment, liquid hydrogen is stored in the hydrogen tank 50, but compressed hydrogen gas may be stored. In addition to the hydrogen tank 50, hydrogen generating means such as a reformer can be used. Further, in the present embodiment, the diluter 30 is used as the exhaust gas treatment means, but a catalytic combustor such as a combustor can also be used.

  In this embodiment, the diluter 30, the pipe 106, and the pipe 107 correspond to heat exchange means, the diluter 30 corresponds to the exhaust gas treatment means, the pipe 106 corresponds to the fuel gas supply pipe, and the pipe 107 corresponds to the fuel exhaust gas. Corresponds to the discharge pipe.

  Subsequently, a fuel cell system 100a according to a second embodiment of the present invention will be described. FIG. 6 is a schematic diagram showing the overall configuration of the fuel cell system 100a. The fuel cell system 100a differs from the fuel cell system 100 of FIG. 1 in that a diluter 30b is provided instead of the diluter 30, and that the ACP driving unit 11, the air compressor 12, the pressure sensor 13, the control unit 60, and The display unit 70 is further provided.

  A branch pipe 108 is provided in the pipe 106 in the diluter 30b. The branch pipe 108 is provided with a relief valve 31. The fuel gas flowing through the pipe 106 flows into the branch pipe 108. Thereby, the gas pressure in the pipe 106 and the gas pressure in the pipe 108 become the same pressure.

  The pressure sensor 13 detects the gas pressure in the pipe 106 and gives the detection result to the control unit 60. The control unit 60 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and the like. The control unit 60 controls the display unit 70 and the ACP driving unit 11 based on the detection result of the pressure sensor 13. The ROM of the control unit 60 contains a program for controlling the fuel cell system 100a.

  The ACP drive unit 11 supplies power stored in a battery (not shown) to the air compressor 12 in accordance with an instruction from the control unit 60. The air compressor 12 compresses air in the air according to the electric power supplied from the ACP driving unit 11 and supplies the compressed air to the humidification module 10 via the pipe 101. The display unit 70 displays information necessary for the driver in accordance with an instruction from the control unit 60.

  Next, the operation of the fuel cell system 100a will be described. When the operation of the fuel cell 20 is stopped, the pressure sensor 13 detects the gas pressure in the pipe 106 every set time, and gives the result to the control unit 60. Since the detection by the pressure sensor 13 is not performed while the fuel cell 20 is being operated, wasteful power consumption can be prevented. The control unit 60 is operated by battery power (not shown) regardless of the operation of the fuel cell 20.

  The relief valve 31 discharges the fuel gas into the diluter 30b via the branch pipe 108 when the gas pressure in the branch pipe 106 exceeds a predetermined value due to a failure of the hydrogen tank 50 or the like. As a result, the gas pressure in the pipe 106 is prevented from exceeding a predetermined pressure. Therefore, the pipe 106 can be prevented from being ruptured or damaged. Further, the fuel gas discharged from the relief valve 31 is discharged to the diluter 30b. Therefore, the hydrogen concentration in the fuel gas discharged from the relief valve 31 can be reduced.

  Furthermore, since the relief valve 31 is provided in the diluter 30b, sound leakage when the relief valve 31 is opened can be reduced. Further, since the fuel gas discharged by the relief valve 31 is discharged into the diluter 30b, it is not necessary to newly provide an exhaust gas processing means for processing the exhaust gas. Thereby, the fuel cell system 100a can be reduced in size. Details of the operation of the relief valve 31 will be described later.

  When fuel gas is discharged from the relief valve 31, the gas pressure in the pipe 106 decreases. In this case, the control unit 60 causes the ACP driving unit 11 to operate the air compressor 12 for a set time. Thereby, compressed air is forcibly supplied to the diluter 30b. As a result, the hydrogen concentration in the fuel gas discharged from the relief valve 31 decreases. Further, the control unit 60 causes the display unit 70 to display that the air compressor 12 has been operated in order to notify the driver that the air compressor 12 has been operated. Therefore, it is possible to cause the driver to carefully perform the next operation of the fuel cell 20.

  When the gas pressure in the pipe 106 does not decrease after the air compressor 12 is operated, the control unit 60 causes the ACP driving unit 11 to continue the operation of the air compressor 12 even after the set time is exceeded. When the operation time of the air compressor 12 is long, the display unit 70 may be configured to notify a person around the vehicle that the gas pressure in the pipe 106 does not decrease.

  Next, details of the structure and operation of the relief valve 31 will be described. FIG. 7 is a schematic cross-sectional view of the relief valve 31. FIG. 7A shows the closed state of the relief valve 31, and FIG. 7B shows the opened state of the relief valve 31. As shown in FIG. 7A, the relief valve 31 includes a coil spring 32, a ball 33, and a discharge port 34. The ball 33 is provided at the outlet of the branch pipe 108. The coil spring 32 applies a force to the ball 33 so that the ball 33 closes the outlet of the branch pipe 108. When the gas pressure in the pipe 106 is less than a predetermined value, the ball 33 closes the outlet of the branch pipe 108.

  When the gas pressure in the pipe 106 exceeds a predetermined value, the fuel gas in the branch pipe 108 pushes up the ball 33 against the force of the coil spring 32 as shown in FIG. As a result, the branch pipe 108 and the discharge port 34 communicate with each other. Therefore, the fuel gas in the pipe 106 is discharged into the diluter 30b.

  FIG. 8 is a diagram illustrating an example of a flowchart when the control unit 60 controls the fuel cell system 100a. The control unit 60 executes the following flowchart at a predetermined cycle. Hereinafter, the operation of the control unit 60 will be described with reference to the flowchart of FIG. First, the control unit 60 causes the pressure sensor 13 to detect the gas pressure in the pipe 106 every set time (step S1). Next, the control unit 60 determines whether or not the fuel cell 20 is in an operating state (step S2).

  When it is determined in step S2 that the fuel cell 20 is in the operating state, the control unit 60 ends the operation. When it is not determined in step S2 that the fuel cell 20 is in the operating state, the control unit 60 determines whether or not the pressure P detected by the pressure sensor 13 is lower than a set value (step S3). When it is determined in step S3 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 ends the operation. If it is not determined in step S3 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 measures the pressure detected by the pressure sensor 13 a set number of times (step S4).

  Next, the control unit 60 determines again whether or not the pressure P detected by the pressure sensor 13 is lower than the set value (step S5). If it is determined in step S5 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 ends the operation. If it is not determined in step S5 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 causes the ACP driving unit 11 to wait (step S6).

  Next, the control unit 60 measures the pressure P detected by the pressure sensor 13 (step S7). Next, the control unit 60 determines whether or not the gas pressure in the pipe 106 has decreased based on the pressure P measured in step S7 (step S8). When it is determined in step S8 that the gas pressure in the pipe 106 has decreased, the control unit 60 ends the operation. If it is not determined in step S8 that the gas pressure in the pipe 106 has decreased, the control unit 60 operates the air compressor 12 (step S9).

  Next, the control unit 60 displays on the display unit 70 that the air compressor 12 has been operated (step S10). Next, the control unit 60 determines again whether or not the pressure P detected by the pressure sensor 13 is lower than the set value (step S11). When it is not determined in step S11 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 stands by. Thereby, the air compressor 12 continues the operation. When it is determined in step S11 that the pressure P detected by the pressure sensor 13 is lower than the set value, the control unit 60 stops the operation of the air compressor 12 (step S12). Thereafter, the control unit 60 ends the operation.

  As described above, when the pressure of the fuel gas in the pipe 106 becomes high, the fuel gas discharged from the relief valve 31 is diluted by the operation of the air compressor 12 and discharged to the outside. Further, since the operation of the air compressor 12 is displayed on the display unit 70, it is possible to cause the driver to carefully operate the fuel cell 20 next time.

  FIG. 9 is a schematic diagram of a diluter 30c which is another example of the diluter 30b according to the present embodiment. The diluter 30c is different from the diluter 30b of FIG. 6 in that the fuel gas discharged from the relief valve 31 is supplied to the catalytic combustion unit 35 and then discharged into the diluter 30c.

  The catalytic combustion unit 35 includes a catalyst that promotes an oxidation reaction of hydrogen in the fuel gas. Thereby, the hydrogen in the fuel gas supplied to the catalyst combustion unit 35 is discharged into the diluter 30c after being burned by the catalyst. Thereafter, the gas burned by the catalyst combustion unit 35 is diluted by the diluter 30c and then discharged to the outside. Therefore, discharge of hydrogen to the outside can be prevented.

  Subsequently, a fuel cell system 100b according to a third embodiment of the present invention will be described. The fuel cell system 100b is different from the fuel cell system 100 of FIG. 1 in that a diluter 30d is provided instead of the diluter 30. Details of the diluter 30d will be described below. FIG. 10 is a diagram for explaining the diluter 30d. FIG. 10A is a schematic diagram of the diluter 30d, and FIG. 10B is a schematic diagram for explaining details of the pipes 106 and 107 in the diluter 30d.

  As shown in FIGS. 10A and 10B, an ejector 36 is inserted in the pipe 106. A branch pipe 109 is provided in the pipe 107. The branch pipe 109 is connected to the ejector 36 via the check valve 37. Next, the operation of the diluter 30d will be described.

  As the amount of power generated in the fuel cell 20 increases, the amount of fuel gas consumed increases. Thereby, the suction force with respect to the piping 106 increases. In this case, suction force also acts on the branch pipe 109 by the ejector 36. When the supply of hydrogen to the pipe 106 by the hydrogen tank 50 does not catch up and the suction force to the branch pipe 109 exceeds the check force of the check valve 37, the anode off-gas flowing through the pipe 107 becomes the branch pipe 109 and the check valve. 37 and the ejector 36 are supplied to the pipe 106.

  In this case, hydrogen contained in the anode off gas can be reused. Thereby, hydrogen required for power generation can be supplied to the fuel cell 20. Moreover, the utilization efficiency of hydrogen improves. Further, the amount of hydrogen to be diluted in the diluter 30d is reduced. Thereby, the hydrogen concentration in the exhaust gas discharged to the outside can be reduced. Note that the check force of the check valve 37 may be adjusted so that the ejector 36 operates in a condition where the amount of hydrogen contained in the anode off gas is large.

  FIG. 11 is a schematic diagram of a diluter 30e which is another example of the diluter 30d of FIG. The diluter 30e differs from the diluter 30d in that a valve 38 is inserted in a branch pipe 109 between the ejector 36 and the check valve 37. The valve 38 opens and closes the branch pipe 109.

  The valve 38 adjusts the amount of anode off gas supplied from the pipe 107 to the diluter 30e by an opening / closing operation. Thereby, the amount of hydrogen required for the power generation of the fuel cell 20 can be adjusted. The valve 38 can also be closed when the check valve 37 is opened due to a failure. This prevents unnecessary anode off gas from being supplied to the pipe 106 from the pipe 107.

  When the temperature of the fuel cell 20 does not reach the predetermined temperature, the low-temperature anode off-gas and the fuel gas are supplied to the diluter 30e. In this case, since the temperature of the diluter 30e is lowered, the check valve 37 may be frozen. The valve 38 closes the branch pipe 109 when the temperature of the fuel cell 20 does not reach a predetermined temperature. Thereby, breakage of the check valve 37 can be prevented.

  When the diluters 30d and 30e are applied to the fuel cell system, it is preferable to provide the inlet shut-off valve 25 and the regulator 26 in FIG. 2 upstream of the diluters 30d and 39e in the pipe 106. FIG. 12 is a schematic diagram in which the inlet shutoff valve 25 and the regulator 26 are provided on the upstream side of the diluters 30d and 30e of the pipe 106. In this case, water vapor contained in the anode off gas is prevented from flowing into the inlet shutoff valve 25 and the regulator 26. Therefore, corrosion of the inlet shutoff valve 25 and the regulator 26 is suppressed. As a result, failure of the inlet shutoff valve 25 and the regulator 26 can be suppressed.

  The fuel cell system according to the present invention may have a configuration in which the second embodiment and the third embodiment are combined. For example, both the relief valve 31 and the ejector 36 may be provided in the pipe 106 in the diluter 30. In this case, the effects of both the second embodiment and the third embodiment can be obtained.

1 is a schematic diagram showing an overall configuration of a fuel cell system according to a first embodiment of the present invention. It is a figure for demonstrating the detail of a fuel cell. It is typical sectional drawing of a fuel gas inlet_port | entrance, an anode off gas exit, and an end plate. It is a typical sectional view of a diluter. It is a figure for demonstrating piping. It is a schematic diagram which shows the whole structure of a fuel cell system. It is a typical sectional view of a relief valve. It is a figure which shows an example of the flowchart at the time of a control part controlling a fuel cell system. It is a schematic diagram of the diluter which is another example of the diluter which concerns on a present Example. It is a figure for demonstrating a diluter. It is a schematic diagram of the other example of a diluter. It is a schematic diagram when an inlet shut-off valve and a regulator are provided upstream from the diluter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ACP drive part 12 Air compressor 13 Pressure sensor 20 Fuel cell 21 Air inlet 22 Cathode off-gas outlet 23, 23a Fuel gas inlet 24, 24a Anode off-gas outlet 27, 27a End plate 30, 30a, 30b, 30c, 30d, 30e Diluter 31 Relief valve 34 Discharge port 35 Catalytic combustion section 36 Ejector 37 Check valve 50 Hydrogen tank 60 Control section 100, 100a, 100b Fuel cell system 106, 107 Piping 108, 109 Branch piping 201 Connecting flange

Claims (6)

A fuel cell that generates power using a fuel gas containing hydrogen and an oxidant gas containing oxygen;
Heat exchange means for heating the fuel gas,
The fuel exchange system, wherein the heat exchanging means heats the fuel gas with fuel exhaust gas and oxidant exhaust gas discharged from the fuel cell. The heat exchange means includes exhaust gas treatment means for treating the fuel exhaust gas and the oxidant exhaust gas,
A fuel gas supply pipe for supplying the fuel gas to the fuel cell;
The fuel cell system according to claim 1, wherein the fuel gas supply pipe passes through the exhaust gas processing means. The heat exchange means further includes a fuel exhaust gas exhaust pipe through which the fuel exhaust gas flows,
3. The fuel cell system according to claim 2, wherein the fuel exhaust gas flowing through the fuel exhaust gas exhaust pipe contacts an outer wall of the fuel gas supply pipe between the exhaust gas processing means and the fuel cell. The fuel cell system according to claim 3, wherein the fuel gas supply pipe passes through the fuel exhaust gas discharge pipe. The fuel cell system according to claim 2, wherein the fuel gas supply pipe includes a relief valve in the exhaust gas processing means. 6. The fuel cell system according to claim 2, wherein the exhaust gas treatment means is a diluter that dilutes the exhaust gas.

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