JP2016110697A - Fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery system that can suppress corrosion of a fuel gas injector due to water vapor fed out from an anode electrode side.SOLUTION: A fuel battery system has a fuel battery stack 10 for generating power through electrochemical reaction between fuel gas and oxidant gas, a fuel gas supply pipe 31 linked to an entrance of a fuel gas passage 30 formed in the fuel battery stack, a fuel gas injector 35 which is disposed in the fuel gas supply pipe and supplies fuel gas to the fuel battery stack, and a porous member 70 disposed in a downstream-side fuel gas supply pipe 31a which is a fuel gas supply pipe at the downstream side of the fuel gas injector.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell system.

  A fuel cell stack that generates electric power by an electrochemical reaction between the fuel gas and the oxidant gas, a fuel gas supply pipe connected to an inlet of a fuel gas passage formed in the fuel cell stack, and a fuel gas supply pipe A fuel cell system including a fuel gas injector that supplies fuel gas to a fuel cell stack is known (see, for example, Patent Document 1).

  In the fuel cell system, generated water generated during operation of the fuel cell stack is discharged as water vapor not only from the cathode electrode side but also from the anode electrode side. Such water vapor is discharged from the outlet of the fuel gas passage and flows into an anode off-gas pipe connected to the outlet of the fuel gas passage.

JP 2007-317597 A

  However, in the fuel cell system, the water vapor discharged from the anode electrode side can be discharged not only from the outlet of the fuel gas passage but also from the inlet by diffusion. In particular, when the fuel gas is not supplied from the fuel gas injector, there is almost no flow of the fuel gas. Therefore, the water vapor flowing out from the inlet of the fuel gas passage may diffuse in the fuel gas supply pipe and reach the fuel gas injector, which may corrode the fuel gas injector. A technique capable of suppressing corrosion of the fuel gas injector due to water vapor flowing out from the anode electrode side is desired.

  According to the present invention, a fuel cell stack that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas, and a fuel gas supply pipe connected to an inlet of a fuel gas passage formed in the fuel cell stack; A fuel gas injector that is disposed in the fuel gas supply pipe and that supplies fuel gas to the fuel cell stack; and a fuel gas supply pipe that is downstream of the fuel gas injector and disposed in a downstream fuel gas supply pipe A fuel cell system is provided.

  According to the present invention, it is possible to suppress corrosion of the fuel gas injector due to water vapor flowing out from the anode side.

It is the schematic which shows the structural example of the fuel cell system of an Example. It is the schematic which shows the structural example near a fuel gas supply pipe | tube. It is the schematic explaining the relationship between a porous member and a water | moisture content. It is the schematic which shows the structural example near a fuel gas supply pipe | tube. It is the schematic which shows the structural example of the fuel cell system of another Example. It is the schematic which shows the structural example near a fuel gas supply pipe | tube. It is the schematic which shows the structural example of the fuel cell system of another Example. It is the schematic which shows the structural example of the fuel cell system of another Example. It is the schematic which shows the structural example near a fuel gas supply pipe | tube. It is the schematic which shows the structural example of the fuel cell system of another Example. It is the schematic which shows the structural example near the fuel gas supply pipe | tube of other Example. It is the schematic which shows the structural example near the fuel gas supply pipe | tube of other Example. It is the schematic explaining the relationship between a porous member and a water | moisture content.

  The fuel cell system A of the embodiment will be described. FIG. 1 is a schematic diagram illustrating a configuration example of a fuel cell system A according to an embodiment. The fuel cell system A includes a fuel cell stack 10. The fuel cell stack 10 includes a stacked body in which a plurality of fuel cell single cells are stacked in the stacking direction. Each single fuel cell includes a membrane electrode assembly 20. The membrane electrode assembly 20 includes a membrane electrolyte, an anode electrode formed on one side of the electrolyte, and a cathode electrode formed on the other side of the electrolyte.

  The anode of the fuel cell is electrically connected to the cathode of another fuel cell adjacent to one side, and the cathode is electrically connected to the anode of another fuel cell adjacent to the other side. . The anode electrode at one end and the cathode electrode at the other end of the stack of fuel cell single cells constitute an electrode of the fuel cell stack 10. The electrode of the fuel cell stack 10 is electrically connected to an inverter via a DC / DC converter, for example, and the inverter is electrically connected to a motor generator such as a vehicle. Moreover, in another Example, the fuel cell system A is provided with an electrical storage like a battery. Illustration of these electrical configurations is omitted.

  Further, in the single fuel cell, a hydrogen gas flow passage for supplying hydrogen gas as fuel gas to the anode electrode, an air flow passage for supplying air as oxidant gas to the cathode electrode, and a single fuel cell. A cooling water flow passage for supplying cooling water to the cell is formed. The hydrogen gas flow passages of the plurality of fuel cell single cells are connected in parallel, the air flow passages of the plurality of fuel cell single cells are connected in parallel, and the cooling water flow passages of the plurality of fuel cell single cells are connected in parallel. A fuel gas passage 30, an oxidant gas passage 40 and a cooling water passage 50 are formed in the battery stack 10.

  A fuel gas supply pipe 31 is connected to a fuel gas supply port that is an inlet of the fuel gas passage 30, and the fuel gas supply pipe 31 is connected to a hydrogen tank 32 that is a fuel gas source. A shutoff valve 33, a regulator 34 for adjusting the pressure of hydrogen gas in the fuel gas supply pipe 31, and a fuel gas injector 35 for injecting hydrogen gas are arranged in the fuel gas supply pipe 31 in order from the upstream side. The In the embodiment shown in FIG. 1, the fuel gas injector 35 includes a needle valve and injects hydrogen gas intermittently. On the other hand, an anode off gas pipe 36 through which a gas flowing out from the fuel gas passage 30, that is, an anode off gas flows, is connected to a fuel gas discharge port that is an outlet of the fuel gas passage 30. A buffer tank 37 for temporarily storing the anode off gas is disposed in the upstream anode off gas pipe 36 a upstream of the anode off gas pipe 36, and an anode in the downstream anode off gas pipe 36 b on the downstream side of the anode off gas pipe 36. An exhaust control valve 38 for controlling off-gas exhaust is disposed. When the shut-off valve 33 is opened and the fuel gas injector 35 is opened, the hydrogen gas in the hydrogen tank 32 is regulated by the regulator 34, the flow rate is adjusted by the fuel gas injector 35, and the fuel gas supply pipe The fuel gas is supplied to the fuel gas passage 30 in the fuel cell stack 10 through the fuel cell stack 10. Therefore, the hydrogen tank 32, the regulator 34, and the fuel gas injector 35 can be regarded as a fuel gas supply device that supplies hydrogen gas (fuel gas) to the fuel cell stack 10. On the other hand, when the shutoff valve 33 is closed or the fuel gas injector 35 is closed, the supply of hydrogen gas to the fuel gas supply pipe 31 is stopped. In another embodiment (not shown), the upstream-side anode off-gas pipe 36a is omitted, and a buffer tank 37 is directly connected to the fuel gas discharge port. In this case, the buffer tank 37 can be regarded as the upstream anode off-gas pipe 36a. In yet another embodiment not shown, the buffer tank 37 in the anode off gas pipe 36 is omitted.

  In the embodiment shown in FIG. 1, hydrogen gas is supplied to the fuel gas supply pipe 31 so that the pressure of the fuel gas supply pipe 31 is maintained at a target pressure determined according to the load of the fuel cell system A, for example. In other words, when the exhaust control valve 38 is closed, the hydrogen gas is supplied to the fuel gas supply pipe 31 so that the hydrogen gas consumed by the fuel cell stack 10 is replenished.

  In contrast, for example, when the exhaust control valve 38 is opened, the fuel gas passage 30 and the buffer tank 37 of the fuel cell stack 10 are scavenged by the hydrogen gas supplied to the fuel gas supply pipe 31. At this time, the anode off gas flowing out from the fuel gas passage 30 and the buffer tank 37, that is, the purge gas is discharged from the exhaust control valve 38.

  As described above, in the fuel cell system A of the embodiment shown in FIG. 1, the fuel gas discharge port that is the outlet of the fuel gas passage 30 and the fuel gas supply pipe 31 are separated, and the anode off-gas containing hydrogen gas is the fuel gas. It can be said that the system does not circulate to the supply pipe 31, that is, a fuel cell non-circulation type fuel cell system.

  An oxidant gas supply pipe 41 is connected to the inlet of the oxidant gas passage 40, and the oxidant gas supply pipe 41 is connected to the atmosphere 42 as an air source. In the oxidant gas supply pipe 41, in order from the upstream side, an air cleaner 43, an air supplier or compressor 44 that pumps air, and an intercooler 45 that cools the air sent from the compressor 44 to the fuel cell stack 10, , Is arranged. On the other hand, a cathode off-gas pipe 46 is connected to the outlet of the oxidant gas passage 40. A cathode offgas control valve 47 for controlling the amount of cathode offgas flowing in the cathode offgas pipe 46 or the pressure in the oxidant gas passage 40 of the fuel cell stack 10 is disposed in the cathode offgas pipe 46. Further, the inlet of the oxidant gas bypass pipe 49 is connected to the oxidant gas supply pipe 41 downstream of the intercooler 45, and the outlet of the oxidant gas bypass pipe 49 is connected to the cathode offgas pipe 46 downstream of the cathode offgas control valve 47. . An oxidant gas bypass control valve 48 is disposed in the oxidant gas bypass pipe 49. The oxidant gas bypass control valve 48 bypasses the fuel cell stack 10 and controls the flow rate of air flowing from the oxidant gas supply pipe 41 to the cathode offgas pipe 46. In the fuel cell system A shown in FIG. 1, the oxidant gas bypass control valve 48 is formed of a three-way valve. The compressor 44 is driven, and the oxidant gas bypass control valve 48 is connected to the oxidant gas supply pipe 41 upstream of the oxidant gas bypass control valve 48, and the oxidant gas downstream of the oxidant gas bypass control valve 48. When the supply pipe 41 is communicated, air is supplied into the oxidant gas passage 40 in the fuel cell stack 10 through the oxidant gas supply pipe 41. Therefore, the compressor 44 can be regarded as an oxidant gas supply device that supplies air (oxidant gas) to the fuel cell stack 10. At this time, the gas flowing out from the oxidant gas passage 40, that is, the cathode off gas flows into the cathode off gas pipe 46. When the oxidant gas bypass control valve 48 communicates with the oxidant gas supply pipe 41 upstream of the oxidant gas bypass control valve 48, a part of the air discharged from the compressor 44 or The whole is supplied to the cathode offgas pipe 46 through the oxidant gas bypass pipe 49.

  A diluter 82 is provided in the cathode offgas pipe 46 downstream of the outlet of the oxidant gas bypass pipe 49. The diluter 82 is connected to the outlet of the downstream anode off-gas pipe 36b. In the diluter 82, the hydrogen gas contained in the anode off gas is diluted with the cathode off gas so that the hydrogen gas concentration in the gas discharged from the diluter 82 to the atmosphere is below an allowable value. The cathode off-gas flowing into the diluter 82 includes the oxidant gas from the oxidant gas bypass pipe 49.

  In addition, one end of a cooling water supply pipe 51 is connected to the inlet of the cooling water passage 50, and one end of a cooling water discharge pipe 59 is connected to the outlet of the cooling water supply pipe 51. A radiator 53 is connected to the other end of the cooling water supply pipe 51 and the other end of the cooling water discharge pipe 59. A cooling water pump 52 that pumps the cooling water is disposed in the cooling water supply pipe 51. The cooling water discharge pipe 59 and the cooling water supply pipe 51 between the radiator 53 and the cooling water pump 52 are connected to each other by a radiator bypass pipe 54. Further, a radiator bypass control valve 55 that controls the flow rate of the cooling water flowing in the radiator bypass pipe 54 is provided. In the fuel cell system A shown in FIG. 1, the radiator bypass control valve 55 is formed of a three-way valve and is disposed at the inlet of the radiator bypass pipe 54. When the cooling water pump 52 is driven, the cooling water discharged from the cooling water pump 52 flows into the cooling water passage 50 in the fuel cell stack 10 through the cooling water supply pipe 51, and then passes through the cooling water passage 50. It flows into the cooling water discharge pipe 59 and returns to the cooling water pump 52 via the radiator 53 or the radiator bypass pipe 54.

  The electronic control unit 60 is composed of a digital computer, and is connected to each other by a bidirectional bus 61. It comprises. Output signals from the output sensor, pressure sensor, temperature sensor (not shown), etc. in the fuel cell system A are input to the input port 65 via the corresponding AD converter 67. On the other hand, the output port 66 is connected to a drive device (not shown) such as a DC / DC converter, an inverter and a motor generator via a corresponding drive circuit 68, a shutoff valve 33, a regulator 34, a fuel gas injector 35, and an exhaust control valve 38. The compressor 44, the cathode off-gas control valve 47, the oxidant gas bypass control valve 48, the cooling water pump 52, and the radiator bypass control valve 55 are electrically connected.

  When hydrogen gas and air are supplied to the fuel cell stack 10, electric energy is generated in the fuel cell stack 10 by an electrochemical reaction between hydrogen and oxygen. This electric energy is supplied to a motor generator such as a vehicle.

  Incidentally, as described above, in the fuel cell system A, during the operation of the fuel cell system A, the water vapor discharged from the anode electrode side flows out from the inlet of the fuel gas passage 30 and passes through the fuel gas supply pipe 31. The fuel gas injector 35 may be diffused and reach the fuel gas injector 35, which may corrode the fuel gas injector 35. Therefore, in the present embodiment, as shown in FIG. 2, the porous member 70 is disposed inside the downstream fuel gas supply pipe 31 a that is the fuel gas supply pipe 31 downstream of the fuel gas injector 35. As a result, the water vapor diffusing into the fuel gas injector 35 in the downstream side fuel gas supply pipe 31a comes into contact with the porous member 70 and is condensed, and the condensed water is returned to the inlet of the fuel gas passage 30 by capillary action. The water vapor is suppressed from reaching the fuel gas injector 35, and the corrosion of the fuel gas injector 35 is suppressed. This will be described in detail below.

  The porous member 70 is formed in a substantially cylindrical shape along the inner wall of the downstream fuel gas supply pipe 31a. A hollow region 71 extending from the downstream end to the upstream end of the porous member 70 is formed in the porous member 70 along the flow path direction of the downstream fuel gas supply pipe 31a. Hydrogen gas and water vapor mainly circulate in the cavity region 71, and condensed water mainly circulates in a portion other than the cavity region 71 of the porous member 70, that is, the porous portion. In the embodiment shown in FIG. 2, the porous member 70 is formed in a cylindrical shape, and the hollow region 71 is a columnar space inside the cylinder. By forming the cavity region 71, the flow resistance of the hydrogen gas sent from the fuel gas injector 35 to the inlet of the fuel gas passage 30 can be reduced. The downstream end of the porous member 70 is disposed adjacent to the inlet 30 a of the fuel gas passage 30. This is because the condensed water is moved as close as possible to the inlet 30a of the fuel gas passage 30. The upstream end of the porous member 70 is disposed away from the fuel gas injector 35. This is because if the upstream end of the porous member 70 is in contact with the fuel gas injector 35, the condensed water in the porous member 70 may reach the fuel gas injector 35. In another embodiment not shown, the hollow region 71 is not formed inside the porous member 70. This is because the water vapor is more reliably condensed. In yet another embodiment (not shown), the hollow region 71 is not formed inside the porous member 70, and when the porous member 70 has a cylindrical shape, for example, the pore diameter is large near the center axis of the column, The pore diameter is small around. Thereby, the flow resistance of the hydrogen gas sent from the fuel gas injector 35 to the inlet of the fuel gas passage 30 can be reduced without forming the cavity region 71. In yet another embodiment (not shown), the downstream end of the porous member 70 is spaced apart from the inlet 30 a of the fuel gas passage 30.

  The size and number of the pores of the porous member 70 are not particularly limited as long as hydrogen gas can permeate and moisture can cause capillary action. Examples of the material for the porous member 70 include metals such as nickel, aluminum and nickel chrome, ceramics such as alumina, silica and zirconia, resins such as polyethylene, polypropylene and polytetrafluoroethylene, and combinations thereof. It is done. Among these, a metal is preferable. This is because heat conductivity is high and condensation heat released when water vapor changes to condensed water can be quickly released to the downstream fuel gas supply pipe 31a. Specifically, for example, porous metal body Celmet (registered trademark) manufactured by Sumitomo Electric Industries, Ltd. may be mentioned.

  In the porous member 70, the portion E1 closer to the fuel cell stack 10, that is, the downstream portion E1 is relatively hot due to the heat of the fuel cell stack 10, and the portion E2 far from the fuel cell stack 10, that is, the upstream portion E2 is a heat source. Because there is no near, it is relatively low temperature. Therefore, the moisture in the fuel gas supply pipe 31 (including the moisture in the porous member 70) tends to become water vapor in the downstream portion E1, and tends to become condensed water in the upstream portion E2.

  Even when the fuel cell stack 10 is not generating power or when the fuel cell stack 10 is generating power, when the hydrogen gas injection from the fuel gas injector 35 is stopped, the downstream fuel gas supply pipe There is no hydrogen gas flow toward the fuel cell stack 10 in 31a. In the porous member 70, as shown in FIG. 3, when the hydrogen gas is not discharged from the fuel gas injector 35, the water vapor w1 flowing out from the inlet 30a of the fuel gas passage 30 is main in the downstream fuel gas supply pipe 31a. The inside of the cavity region 71 is diffused toward the fuel gas injector 35. The water vapor w1 cools as it leaves the fuel cell stack 10, and eventually comes into contact with the portion E2 on the upstream side of the low-temperature porous member 70 to condense into condensed water w2. The condensed water w <b> 2 moves in the porous member 70 toward the inlet 30 a side of the fuel gas passage 30, that is, the fuel cell stack 10 side due to capillary action in the porous member 70. The condensed water w2 warms as it approaches the fuel cell stack 10, and eventually evaporates from the porous member 70 into the water vapor w1 again at the downstream portion E1 of the porous member 70 having a high temperature. Here, when hydrogen gas is discharged from the fuel gas injector 35, the water vapor w <b> 1 is returned to the fuel cell stack 10 together with the hydrogen gas discharged from the fuel gas injector 35 through the inlet 30 a of the fuel gas passage 30. Thereby, it is suppressed that water vapor | steam reaches | attains the fuel gas injector 35, Therefore, corrosion of the fuel gas injector 35 is suppressed. On the other hand, when hydrogen gas is not discharged from the fuel gas injector 35, the water vapor w1 again diffuses mainly in the cavity region 71 toward the fuel gas injector 35, and is condensed again at the upstream portion E2 of the porous member 70. It becomes condensed water w2 and moves to the fuel cell stack 10 side by capillary action. That is, even when hydrogen gas is not discharged from the fuel gas injector 35, the water vapor w1 becomes condensed water w2 again and is returned to the fuel cell stack 10 side. Corrosion of the injector 35 is suppressed.

  In another embodiment shown in FIG. 4, a check valve 35 a that allows a flow only from the fuel gas injector 35 to the fuel cell stack 10 is inserted between the porous member 70 and the fuel gas injector 35. When the water vapor that has not been condensed in the porous member 70 has diffused toward the fuel gas injector 35, the check valve 35 a blocks the diffusion of water vapor into the fuel gas injector 35 and supplies the fuel gas injector 35 with the water vapor. The entrance of water vapor can be more reliably suppressed.

  Next, with reference to FIG.5 and FIG.6, the fuel cell system A of another Example is demonstrated. The fuel cell system A shown in FIGS. 5 and 6 is provided with a cooling structure 72 that cools the upstream portion E2 of the porous member 70 from the outside of the downstream fuel gas supply pipe 31a with a cooling medium. 1 is different from the fuel cell system A shown in FIG. In this case, the cooling medium is cooling water in the cooling water supply pipe 51. Hereinafter, the difference will be mainly described.

  As shown in FIG. 5, a cooling water supply pipe 51 extends around the downstream fuel gas supply pipe 31a. Further, as shown in FIG. 6, the cooling structure 72 is a cooling system that supplies the outside of the downstream fuel gas supply pipe 31 a including the upstream portion E <b> 2 of the porous member 70 via the cooling water supply pipe 51. It is formed so that it can be cooled with water. The cooling structure 72 can be regarded as a heat exchanger in which the cooling water from the cooling water supply pipe 51 is a low-temperature heat medium and the water vapor in the downstream fuel gas supply pipe 31a is a high-temperature heat medium.

  The cooling water pump 52 is driven, and the cooling water discharged from the cooling water pump 52 flows into the cooling structure 72 through the cooling water supply pipe 51, and then the porous member 70 is cooled by the cooling structure 72, and then cooled. It is supplied from the structure 72 to the inlet of the cooling water passage 50 of the fuel cell stack 10 through the cooling water supply pipe 51.

  Also in this case, the same effect as in the embodiment of FIG. 1 can be obtained. In addition, since the upstream portion E2 of the porous member 70 is cooled by the cooling water and becomes a lower temperature, the steam w1 that diffuses the downstream fuel gas supply pipe 31a toward the fuel gas injector 35 is more efficient. Can be condensed into condensed water w2. The cooling water flowing into the cooling structure 72 via the cooling water supply pipe 51 is a relatively low-temperature cooling water that has not been used for cooling the fuel cell stack 10 after being cooled by the radiator 53. Therefore, the upstream portion E2 of the porous member 70 can be cooled more efficiently. Moreover, since the cooling water for cooling the fuel cell stack 10 is used as the cooling medium, it is not necessary to prepare a new cooling medium.

  In another embodiment (not shown), a branch pipe that branches from the cooling water supply pipe 51 and returns to the cooling water supply pipe 51 and a control valve that controls the flow rate of the cooling water flowing in the branch pipe are provided. It extends around the gas supply pipe 31a.

  Next, a fuel cell system A of still another embodiment will be described with reference to FIG. The fuel cell system A shown in FIG. 7 is different from the fuel cell system A shown in FIG. 5 in that the cooling structure 72 is provided in the vicinity of the cooling fan 53a of the radiator 53. In this case, the cooling medium is air blown by the cooling fan 53a. Hereinafter, the difference will be mainly described.

  As shown in FIG. 7, since the cooling structure 72 uses air blown by the cooling fan 53a as a cooling medium, the cooling water supply pipe 51 and the cooling water discharge pipe 59 are not connected to the cooling structure 72 and are cooled to the cooling structure 72. Do not supply water. The cooling structure 72 is disposed between the radiator 53 and the cooling fan 53a including the front and rear downstream fuel gas supply pipes 31a, for example. Examples of the cooling structure 72 include heat exchange fins and heat sinks formed outside the downstream fuel gas supply pipe 31a. In another embodiment (not shown), there is no cooling structure 72, and the upstream portion of the downstream fuel gas supply pipe 31a is simply disposed between the radiator 53 and the cooling fan 53a.

  Also in this case, the same effect as in the embodiment of FIG. 5 can be obtained.

  Next, a fuel cell system A of still another embodiment will be described with reference to FIGS. The fuel cell system A shown in FIGS. 8 and 9 is further provided with a heating structure 73 that heats the downstream portion E1 of the porous member 70 from the outside of the downstream fuel gas supply pipe 31a with a heat medium. 1 is different from the fuel cell system A shown in FIG. In this case, the heat medium is oxidant gas in the oxidant gas supply pipe 41 on the downstream side of the compressor 44. Hereinafter, the difference will be mainly described.

  As shown in FIG. 8, an oxidant gas supply pipe 41 downstream of the compressor 44 extends around the downstream fuel gas supply pipe 31a. As shown in FIG. 9, the heating structure 73 is supplied to the outside of the downstream fuel gas supply pipe 31 a including the downstream portion E <b> 1 of the porous member 70 through the oxidant gas supply pipe 41. It is formed so that it can be heated with air. The heating structure 73 can be regarded as a heat exchanger that uses air from the oxidant gas supply pipe 41 as a high-temperature heat medium and condensate in the downstream fuel gas supply pipe 31a as a low-temperature heat medium.

  When the compressor 44 is driven and the air whose pressure has been increased to a high temperature is discharged from the compressor 44, the air flows into the heating structure 73 via the oxidant gas supply pipe 41, and then the porous structure is heated in the heating structure 73. The member 70 is heated and then supplied from the heating structure 73 to the inlet of the oxidant gas passage 40 of the fuel cell stack 10 through the oxidant gas supply pipe 41.

  Also in this case, the same effect as in the embodiment of FIG. 1 can be obtained. In addition, since the downstream portion E1 of the porous member 70 is heated to a higher temperature by the high-temperature air, the condensation moves through the downstream fuel gas supply pipe 31a toward the inlet 30a of the fuel gas passage 30. The water w2 can be evaporated more efficiently to the water vapor w1. Moreover, since air for generating electric power in the fuel cell stack 10 is used as the heat medium, it is not necessary to prepare a new heat medium.

  Another embodiment (not shown) includes a branch pipe that branches from the oxidant gas supply pipe 41 downstream of the compressor 44 and returns to the oxidant gas supply pipe 41, and a control valve that controls the flow rate of air flowing in the branch pipe. A pipe extends around the downstream fuel gas supply pipe 31a.

  Next, a fuel cell system A of still another embodiment will be described with reference to FIG. The fuel cell system A shown in FIG. 10 uses the cooling water immediately after the heating structure 73 cools the fuel cell stack 10, that is, the cooling water heated in the fuel cell stack 10 as a heat medium. Different from system A. In this case, the heat medium is cooling water in the cooling water discharge pipe 59. Hereinafter, the difference will be mainly described.

  As shown in FIG. 10, a cooling water discharge pipe 59 extends around the downstream fuel gas supply pipe 31a.

  Also in this case, the same effect as in the embodiment of FIG. 8 can be obtained.

  In another embodiment (not shown), a branch pipe branched from the cooling water discharge pipe 59 and returned to the cooling water discharge pipe 59 and a control valve for controlling the flow rate of the cooling water flowing in the branch pipe are provided. It extends around the gas supply pipe 31a.

  Regarding the cooling structure 72 and the heating structure 73 described above, any one of the cooling structure 72 in FIG. 5 and the cooling structure 72 in FIG. 7, the heating structure 73 in FIG. 8, and the heating structure 73 in FIG. Any one can be implemented at the same time. For example, in FIG. 11, the cooling structure 72 of FIG. 5 and the heating structure of FIG. 8 are combined and implemented simultaneously.

  Next, a fuel cell system A according to still another embodiment will be described with reference to FIGS. In the fuel cell system A shown in FIGS. 12 and 13, the downstream fuel gas supply pipe 31a is formed such that the height position of the upstream portion 31a2 is higher than the height position of the downstream portion 31a1. This is different from the fuel cell system A shown in FIG. Hereinafter, the difference will be mainly described.

  Referring to FIG. 12, the extending direction 31as in which the downstream fuel gas supply pipe 31a extends from the inlet 30a of the fuel gas passage 30 toward the fuel gas injector 35 is inclined by the inclination angle SA with respect to the horizontal direction HR. As a result, the downstream portion 31a1 of the downstream fuel gas supply pipe 31a is lower than the upstream portion 31a2 of the downstream fuel gas supply pipe 31a.

  The porous member 70 is formed in a substantially cylindrical shape along the inner wall of the upstream portion 31a2 of the downstream fuel gas supply pipe 31a. A hollow region 71 is formed inside the porous member 70. The downstream end of the porous member 70 is disposed away from the inlet 30 a of the fuel gas passage 30, and the upstream end of the porous member 70 is disposed away from the fuel gas injector 35. In the porous member 70, fuel gas and water vapor circulate and condensed water also circulates. In another embodiment not shown, the cavity region 71 is not formed. In yet another embodiment (not shown), the downstream end of the porous member 70 is disposed adjacent to the inlet 30 a of the fuel gas passage 30.

  Since the porous member 70 is away from the fuel cell stack 10, it is at a relatively low temperature. Therefore, the water in the fuel gas supply pipe 31 (including the water in the porous member 70) tends to be condensed water.

  In the porous member 70, as shown in FIG. 13, when the fuel gas is not discharged from the fuel gas injector 35, the water vapor w1 flowing out from the inlet 30a of the fuel gas passage 30 is fueled in the downstream fuel gas supply pipe 31a. It diffuses toward the gas injector 35. The water vapor w1 cools as it moves away from the fuel cell stack 10, and eventually condenses and condensates in the porous member 70 having a low temperature disposed in the upstream portion 31a2 of the downstream fuel gas supply pipe 31a. become. The condensed water w2 flows in the porous member 70 toward the inlet 30a side of the fuel gas passage 30, that is, to the fuel cell stack 10 side, and then on the inner wall of the downstream fuel gas supply pipe 31a due to capillary action and gravity in the porous member 70. Moving. The condensed water w2 warms as it approaches the fuel cell stack 10, and eventually evaporates from the inner wall of the downstream fuel gas supply pipe 31a in the downstream portion 31a1 of the downstream fuel gas supply pipe 31a to become water vapor w1 again. . Here, when the fuel gas is discharged from the fuel gas injector 35, the water vapor w1 is returned to the fuel cell stack 10 through the inlet 30a of the fuel gas passage 30 together with the fuel gas discharged from the fuel gas injector 35. Thereby, it is suppressed that water vapor | steam reaches | attains the fuel gas injector 35, Therefore, corrosion of the fuel gas injector 35 is suppressed. On the other hand, when the fuel gas is not discharged from the fuel gas injector 35, the water vapor w1 again diffuses in the downstream fuel gas supply pipe 31a toward the fuel gas injector 35 and is condensed again by the porous member 70 to become condensed water w2. It moves to the fuel cell stack 10 side by capillary action and gravity. Thereby, even when the fuel gas is not discharged from the fuel gas injector 35, the water vapor w1 becomes the condensed water w2 and is returned to the fuel cell stack 10, so that the water vapor is prevented from reaching the fuel gas injector 35, and therefore the fuel gas Corrosion of the injector 35 is suppressed.

  The embodiments shown in FIGS. 12 and 13 are also applicable to the above-described embodiments.

  In each of the above embodiments, the fuel cell system A is a system in which the fuel gas discharge port that is the outlet of the fuel gas passage 30 and the fuel gas supply pipe 31 are separated, and the anode off-gas containing hydrogen gas does not circulate to the fuel gas supply pipe 31. That is, a fuel gas non-circulating fuel cell system. In another embodiment (not shown), in the fuel cell system A, the fuel gas discharge port that is the outlet of the fuel gas passage 30 and the fuel gas supply pipe 31 are connected, and the anode off-gas containing hydrogen gas is supplied to the fuel gas supply pipe 31. A circulating system, that is, a fuel cell circulation type fuel cell system. In other words, each of the above embodiments can also be applied to a system that circulates to the fuel gas supply pipe 31.

A fuel cell system 10 fuel cell stack 30 fuel gas passage 30a inlet of fuel gas passage 31 fuel gas supply pipe 31a downstream fuel gas supply pipe 35 fuel gas injector 70 porous member

Claims (10)

A fuel cell stack that generates power by an electrochemical reaction between the fuel gas and the oxidant gas;
A fuel gas supply pipe connected to an inlet of a fuel gas passage formed in the fuel cell stack;
A fuel gas injector disposed in the fuel gas supply pipe for supplying fuel gas to the fuel cell stack;
A porous member disposed inside a downstream fuel gas supply pipe which is the fuel gas supply pipe downstream of the fuel gas injector;
Comprising
Fuel cell system. The porous member is formed in a cylindrical shape along the inner wall of the fuel gas supply pipe.
The fuel cell system according to claim 1. In the porous member, a downstream end of the porous member is disposed adjacent to an inlet of the fuel gas passage, and an upstream end of the porous member is disposed apart from the fuel gas injector.
The fuel cell system according to claim 1 or 2. A cooling structure for cooling the upstream portion of the porous member with a cooling medium from the outside of the fuel gas supply pipe;
The fuel cell system according to any one of claims 1 to 3. A cooling water supply pipe connected to an inlet of a cooling water passage formed in the fuel cell stack;
A cooling water discharge pipe connected to an outlet of a cooling water passage formed in the fuel cell stack;
A cooling water pump disposed in the cooling water supply pipe or the cooling water discharge pipe;
A radiator disposed between the cooling water supply pipe and the cooling water discharge pipe;
Further comprising
The cooling medium is cooling water in the cooling water supply pipe.
The fuel cell system according to claim 4. A cooling water supply pipe connected to an inlet of a cooling water passage formed in the fuel cell stack;
A cooling water discharge pipe connected to an outlet of a cooling water passage formed in the fuel cell stack;
A cooling water pump disposed in the cooling water supply pipe or the cooling water discharge pipe;
A radiator disposed between the cooling water supply pipe and the cooling water discharge pipe;
A cooling fan for blowing air to the radiator;
Further comprising
The cooling medium is air blown from the cooling fan.
The fuel cell system according to claim 4. A heating structure for heating the downstream portion of the porous member with a heat medium from the outside of the fuel gas supply pipe;
The fuel cell system according to any one of claims 1 to 6. An oxidant gas supply pipe connected to an inlet of an oxidant gas passage formed in the fuel cell stack;
A compressor disposed in the oxidant gas supply pipe and pumping the oxidant gas to the oxidant gas supply pipe;
Further comprising
The heat medium is an oxidant gas in the oxidant gas supply pipe on the downstream side of the compressor.
The fuel cell system according to claim 7. A cooling water supply pipe connected to an inlet of a cooling water passage formed in the fuel cell stack;
A cooling water discharge pipe connected to an outlet of a cooling water passage formed in the fuel cell stack;
A cooling water pump disposed in the cooling water supply pipe or the cooling water discharge pipe;
A radiator disposed between the cooling water supply pipe and the cooling water discharge pipe;
Further comprising
The heat medium is cooling water of the cooling water discharge pipe.
The fuel cell system according to claim 7. The fuel cell according to any one of claims 1 to 9, wherein the downstream fuel gas supply pipe is formed such that a height position of an upstream portion is higher than a height position of a downstream portion. system.

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