Fuel cell system

Abstract

To provide a fuel cell system capable of excellently removing ammonium sulfate in air supplied from an air supply system to a fuel cell.SOLUTION: A fuel cell system includes: a fuel cell that generates electricity by an electrochemical reaction between anode gas and cathode gas; an air supply system that supplies air as cathode gas to the fuel cell; an ammonium sulfate prehension tank that catches ammonium sulfate in the air that is contained in the air supply system and supplied to the fuel cell; and an air pipe for introducing air into an internal passage of the ammonium sulfate prehension tank. A passage cross-sectional area of the internal passage of the ammonium sulfate prehension tank is twice or more than that of the air pipe.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a fuel cell system including a fuel cell that generates electricity through an electrochemical reaction between an anode gas and a cathode gas. [Background technology]

[0002] Conventionally, a fuel cell system capable of detecting the timing required for improving the air flow state in an air supply system including an air filter, an air blower, and an air supply passage is known (see, for example, Patent Document 1). In this fuel cell system, when the timing required for improvement is detected, normal operation in which the reforming water pump, the raw fuel pump, and the air blower are operated is terminated (shutdown), and an air flow improvement operation is executed. In the air flow improvement operation, the raw fuel pump and the air blower are stopped, and reforming water is supplied to the evaporator from the reforming water pump through the reforming water supply passage. The reforming water is evaporated in the evaporator by the residual heat in the evaporator, the combustion section, and the storage container, and the high-temperature steam generated in the evaporator is supplied to the reformer and heated by the residual heat of the reformer, and distributed and supplied to each fuel electrode of a plurality of cells via a manifold. Furthermore, the steam flows through the fuel electrodes of each cell and is discharged to the combustion space of the combustion section. Most of the high-temperature steam discharged into the combustion space flows into the air supply passage, passes through the air flow meter and air filter, flows backward through the air supply passage, and is discharged outside the storage vessel. As a result, deposits, such as ammonium sulfate, adhering to the air flow meter and air filter are deliquesced and removed by the steam flowing backward through the air supply passage, improving the air flow condition of the air supply system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-155333 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, ammonium sulfate is the main component of PM2.5, and the air supplied to the fuel cell from the air supply system may contain a relatively large amount of ammonium sulfate. In addition, if a large amount of ammonium sulfate adheres to the air flow meter, it becomes impossible to accurately grasp the flow rate of the air supplied to the fuel cell, which may lead to a decrease in the performance of the fuel cell system. For this reason, it is necessary to remove as much ammonium sulfate as possible from the air supplied to the fuel cell from the air supply system, but the above-mentioned Patent Document 1 does not disclose or suggest a method for removing ammonium sulfate from the air supplied to the fuel cell.

[0005] Therefore, a primary object of the present disclosure is to provide a fuel cell system that can effectively remove ammonium sulfate from the air supplied to the fuel cell from an air supply system. [Means for solving the problem]

[0006] The fuel cell system disclosed herein includes a fuel cell that generates electricity through an electrochemical reaction between an anode gas and a cathode gas, and an air supply system that supplies air to the fuel cell as the cathode gas, the air supply system including an ammonium sulfate capture tank that captures ammonium sulfate in the air supplied to the fuel cell, and air piping for introducing air into an internal passage of the ammonium sulfate capture tank, and the cross-sectional area of ​​the internal passage of the ammonium sulfate capture tank is at least twice the cross-sectional area of ​​the air piping.

[0007] The air supply system of the fuel cell system disclosed herein includes an ammonium sulfate capture tank that captures ammonium sulfate in the air supplied to the fuel cell, and an air pipe for introducing air into the internal passage of the ammonium sulfate capture tank. The cross-sectional area of ​​the internal passage of the ammonium sulfate capture tank is at least twice as large as the cross-sectional area of ​​the air pipe. This reduces the flow rate of air flowing from the air pipe into the ammonium sulfate capture tank by at least half, and significantly reduces the kinetic energy of the air in the internal passage, allowing air to convect in the ammonium sulfate capture tank. As a result, high-density ammonium sulfate is deposited in the ammonium sulfate capture tank, making it possible to effectively remove ammonium sulfate from the air supplied to the fuel cell from the air supply system. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a fuel cell system according to the present disclosure; [Diagram 2] 1 is a cross-sectional view showing a flow meter included in a fuel cell system of the present disclosure. [Diagram 3] 1 is a cross-sectional view showing an ammonium sulfate capture tank included in a fuel cell system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Next, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram showing a fuel cell system 10 according to the present disclosure. The fuel cell system 10 shown in the figure includes a power generation module 20, a raw fuel gas supply system 30, a reforming water supply system 40, an exhaust heat recovery system 45, an air supply system 50, and a housing 11 that houses these components. The power generation module 20 also includes a fuel cell stack 21, an evaporator 22, a reformer 23, a combustor 25 having an ignition device 24, a heat exchanger 26, and a module case 27. The module case 27 has thermal insulation properties and houses the fuel cell stack 21, the evaporator 22, the reformer 23, the combustor 25, and the heat exchanger 26.

[0011] The fuel cell stack 21 of the power generation module 20 generates power by an electrochemical reaction between hydrogen in an anode gas (fuel gas) and oxygen in a cathode gas (oxidant gas), and is formed by stacking a plurality of flat plate-shaped unit cells S in the thickness direction. Each unit cell S is a solid oxide fuel cell (SOFC) including an electrolyte, an anode disposed on one side of the electrolyte, and a cathode disposed on the other side of the electrolyte. As shown in FIG. 1, an anode gas pipe 71 is connected to the anode inlet of the fuel cell stack 21, and a cathode gas pipe 72 is connected to the cathode inlet of the fuel cell stack 21. In addition, an anode off-gas pipe 73 is connected to the anode outlet of the fuel cell stack 21, and a cathode off-gas pipe 74 is connected to the cathode outlet of the fuel cell stack 21.

[0012] The evaporator 22, reformer 23, and combustor 25 of the power generation module 20 are disposed within a module case 27 so as to be located above the fuel cell stack 21. The evaporator 22 includes a large number of heat storage balls (ceramic or stainless steel balls) that are filled therein and that store heat from the combustor 25. The evaporator 22 evaporates reforming water supplied to the large number of balls to generate water vapor. The water vapor generated in the evaporator 22 is mixed with the raw fuel gas, and the resulting mixed gas flows from the evaporator 22 into the reformer 23.

[0013] The reformer 23 has a Ru-based or Ni-based reforming catalyst filled therein, and generates hydrogen gas and carbon monoxide by a reaction (steam reforming reaction) of the mixed gas from the evaporator 22 with the reforming catalyst in the presence of heat from the combustor 25. Furthermore, the reformer 23 generates hydrogen gas and carbon dioxide by a reaction (carbon monoxide shift reaction) between the carbon monoxide generated in the steam reforming reaction and steam. As a result, the reformer 23 generates an anode gas containing hydrogen, carbon monoxide, carbon dioxide, steam, unreformed raw fuel gas, and the like. In this embodiment, the reformer 23 is disposed so as to cover the combustor 25, and heat from the combustor 25 is transferred to the reformer 23.

[0014] The anode gas generated by the reformer 23 is supplied to the anode of each unit cell S via an anode gas pipe 71. Furthermore, air is supplied to the cathode of each unit cell S as a cathode gas containing oxygen via a cathode gas pipe 72. In the cathode of each unit cell S, oxide ions (O 2- ) is generated, and the oxide ions permeate the electrolyte and react with hydrogen and carbon monoxide at the anode to obtain electric energy. Meanwhile, anode gas (hereinafter referred to as "anode offgas") that has not been used in the electrochemical reaction (power generation) in each unit cell S is supplied to the combustor 25 via an anode offgas pipe 73. Cathode gas (hereinafter referred to as "cathode offgas") that has not been used in the electrochemical reaction (power generation) in each unit cell S is also supplied to the combustor 25 via a cathode offgas pipe 74. The anode offgas is a combustible gas that contains fuel components such as hydrogen and carbon monoxide, and the cathode offgas contains oxygen.

[0015] The combustor 25 ignites a mixed gas (offgas) of anode offgas and cathode offgas from the fuel cell stack 21 using an ignition device 24, and burns the mixed gas. As the mixed gas is burned, a combustion exhaust gas containing water vapor is generated in the combustor 25. The combustion exhaust gas passes through the reformer 23, the heat exchanger 26, and the evaporator 22 in this order, providing each device with heat required for reactions, etc., and then flows into the combustion exhaust gas piping 75.

[0016] The raw fuel gas supply system 30 supplies a hydrocarbon-based raw fuel gas (e.g., natural gas or LP gas) that serves as a raw material for the anode gas to the power generation module 20. The raw fuel gas supply system 30 includes a raw fuel gas supply pipe that connects a raw fuel supply source Gs that supplies the raw fuel gas and the evaporator 22 in the module case 27, an on-off valve (two valves) that are arranged in sequence from upstream to downstream on the raw fuel gas supply pipe, a flow sensor, a gas pump, and a desulfurizer. By operating the gas pump, the raw fuel gas from the raw fuel supply source Gs is pumped (supplied) to the evaporator 22 via the desulfurizer.

[0017] The reforming water supply system 40 supplies the power generation module 20 with reforming water necessary for reforming (steam reforming) the raw fuel gas into anode gas, and is disposed within the housing 11 so as to be located below the power generation module 20. The reforming water supply system 40 includes a reforming water supply pipe 41 connected to the evaporator 22 in the module case 27, a reforming water tank 42 connected to the reforming water supply pipe 41 and storing reforming water, and a reforming water pump 43 installed in the reforming water supply pipe 41. By operating the reforming water pump 43, the reforming water in the reforming water tank 42 is pumped (supplied) by the reforming water pump 43 to the evaporator 22.

[0018] The exhaust heat recovery system 45 recovers the exhaust heat generated in the power generation module 20, and is disposed in the housing 11 so as to be located below the power generation module 20. The exhaust heat recovery system 45 includes a hot water storage tank 46 for storing hot water, a condenser 47, a circulation pipe 48 connected to the hot water storage tank 46 and the condenser 47, and a circulation pump 49. The hot water stored in the hot water storage tank 46 is introduced into the condenser 47 through the circulation pipe 48 by operating the circulation pump 49. The condenser 47 exchanges heat between the hot water and the combustion exhaust gas flowing through the combustion exhaust gas pipe 75, and condenses the water vapor contained in the combustion exhaust gas. The hot water from the hot water storage tank 46 is heated by heat exchange with the combustion exhaust gas in the condenser 47, and then returned to the hot water storage tank 46.

[0019] Furthermore, a combustion catalyst (oxidation catalyst) for combusting unburned fuel contained in the combustion exhaust gas is installed at the inlet of the combustion exhaust gas of the condenser 47. The combustion exhaust gas from which water vapor has been removed in the condenser 47 is discharged into the atmosphere via a combustion exhaust gas piping (see the dotted line in FIG. 1). Furthermore, the condensed water obtained in the condenser 47 is introduced into the reforming water tank 42 via a condensed water piping. A water purifier (not shown) for purifying the condensed water from the condensed water piping is installed in the reforming water tank 42.

[0020] The air supply system 50 supplies air as a cathode gas to the power generation module 20 (fuel cell stack 21), and is disposed within the housing 11 so as to be located below the power generation module 20. The air supply system 50 includes an air filter 51, an air pump 52, an air supply pipe 53, a flow meter 54, and an ammonium sulfate capture tank 55. The air filter 51 is attached to the bottom plate of the housing 11 so that air flows in from below in order to prevent substances with high density in the air from being sucked in by the air pump 52. The air pump 52 sucks in air as a cathode gas through the air filter 51, and pressure-feeds (supplies) the sucked air to the air supply pipe 53.

[0021] The air supply pipe 53 is connected to a cathode gas pipe 72 in the module case 27 via the heat exchanger 26. The flow meter 54 detects the flow rate per unit time of air supplied from the air pump 52 to the air supply pipe 53. The ammonium sulfate capture tank 55 is capable of capturing ammonium sulfate in the air supplied to the fuel cell stack 21 via the air supply system 50. The air supplied to the power generation module 20 from the air supply system 50 is heated to a required temperature by heat exchange with the high-temperature combustion exhaust gas discharged from the combustor 25 in the heat exchanger 26, and is then supplied to the cathode of each unit cell S of the fuel cell stack 21 via the cathode gas pipe 72.

[0022] In the fuel cell system 10, a power conditioner (not shown) is connected to the output terminal of the fuel cell stack 21, and the power conditioner is connected to a power line from the power grid via a relay (not shown). The power conditioner includes a DC / DC converter that converts the DC power output from the fuel cell stack 21 into DC power of a predetermined voltage (e.g., DC 250V to 300V), and an inverter that converts the DC power into AC power of a voltage (e.g., AC 200V) that can be connected to the power grid. This makes it possible to convert the DC power from the fuel cell stack 21 into AC power and supply it to a load such as a home appliance connected to the power line.

[0023] Furthermore, a power supply board is connected to the power conditioner. The power supply board converts DC power from the fuel cell stack 21 and AC power from the power system into low-voltage DC power and supplies it to various auxiliary devices, sensors, control devices, etc. The power conditioner and the power supply board are placed in an auxiliary device room (not shown) in the housing 11, and are cooled by a cooling fan (not shown) installed in the auxiliary device room. The air that has been heated by cooling the power conditioner, etc. is exhausted into the atmosphere by a ventilation fan installed in the auxiliary device room.

[0024] In addition, the fuel cell system 10 includes a control device (not shown) that controls the entire system. The control device includes a computer having a CPU, ROM, RAM, input / output devices, etc. The control device acquires detection values ​​of the temperature sensor, pressure sensor, flow meter, voltage sensor, current sensor, etc. of the fuel cell system 10, and controls controlled objects such as the raw fuel gas supply system 30, the reforming water supply system 40, the exhaust heat recovery system 45, the air supply system 50, the power conditioner, the power supply board, etc. based on the acquired detection values, etc. Furthermore, the control device executes various controls based on signals from a remote control (not shown) operated by a user of the fuel cell system 10.

[0025] 2 is a cross-sectional view showing an ammonium sulfate capture tank 55 included in the air supply system 50 of the fuel cell system 10. The ammonium sulfate capture tank 55 is a sealed container formed of a resin that is difficult to hydrolyze, such as polyphenylene sulfide (PPS). In this embodiment, the ammonium sulfate capture tank 55 is a cylinder with both ends closed, and includes an internal passage 55p having a circular cross-sectional shape. However, the internal passage 55p is not limited to having a circular cross-sectional shape. The ammonium sulfate capture tank 55 is disposed between the air pump 52 and the upper power generation module 20 (fuel cell stack 21), more specifically, between the air pump 52 and the flow meter 54, so that the internal passage 55p extends in the vertical direction.

[0026] As shown in Figs. 1 and 2, a first air pipe 56 and a second air pipe 57 are connected to the ammonium sulfate capture tank 55. The first air pipe 56 is connected to the discharge port of the air pump 52, and is connected to the ammonium sulfate capture tank 55 so as to communicate with the internal passage 55p from the lateral direction (approximately perpendicular direction) above the bottom 55b of the internal passage 55p and below the second air pipe 57. That is, the first air pipe 56 from the air pump 52 and the internal passage 55p of the ammonium sulfate capture tank 55 intersect in a substantially T-shape. The second air pipe 57 is connected to the air supply pipe 53 via the flowmeter 54, and is connected to the ammonium sulfate capture tank 55 so as to communicate with the internal passage 55p from the lateral direction (approximately perpendicular direction) below the ceiling portion 55s of the internal passage 55p and above the first air pipe 56. That is, the second air pipe 57 on the air supply pipe 53 side and the internal passage 55p of the ammonium sulfate capture tank 55 intersect in a substantially T-shape.

[0027] The inner diameter R of the internal passage 55p of the ammonium sulfate capture tank 55 and the inner diameter r1 of the first air pipe 56 are set so that the passage cross-sectional area of ​​the internal passage 55p is equal to the density of ammonium sulfate, which is the main component of PM2.5 contained in the air (approximately 1.7 g / cm 3 ) and the like, the inner diameter R of the internal passage 55p is determined to be at least twice the passage cross-sectional area of ​​the first air pipe 56. In this embodiment, the inner diameter R of the internal passage 55p is determined to be, for example, 1.5 to 2 times the inner diameter r1 of the first air pipe 56. Furthermore, the inner diameter r2 of the second air pipe 57 is also determined so that the passage cross-sectional area of ​​the internal passage 55p is at least twice the passage cross-sectional area of ​​the second air pipe 57. In this embodiment, the inner diameter R of the internal passage 55p is determined to be, for example, 1.5 to 2 times the inner diameter r2 of the second air pipe 57. The passage cross-sectional area (inner diameter r1) of the first air pipe 56 and the passage cross-sectional area (inner diameter r2) of the second air pipe 57 may be the same as each other or may be different from each other. In addition, the cross-sectional area of ​​the internal passage 55p is preferably determined to be four times or less the cross-sectional area of ​​the first and second air pipes 56, 57, taking into consideration the outflow of air to the air supply pipe 53 (flow meter 54) side, the mountability of the ammonium sulfate capture tank 55, etc.

[0028] On the other hand, in this embodiment, the flowmeter 54 of the air supply system 50 is a thermal flowmeter that detects the flow rate per unit time of air supplied from the air pump 52 to the air supply pipe 53 by a power consumption measurement method or a temperature difference measurement method. As shown in Fig. 3, the flowmeter 54 includes an air inlet 54i on the ammonium sulfate capture tank 55 (air pump 52) side, an air outlet 54o on the air supply pipe 53 (fuel cell stack 21) side, a main passage 54p that communicates between the air inlet 54i and the air outlet 54o, and a bypass passage 54b branched off from the main passage 54p. The main passage 54p of the flowmeter 54 includes, in the center in the air flow direction, a small-diameter passage 54n that is smaller in diameter (has a smaller passage cross-sectional area) and shorter than the portion of the main passage 54p on the air inlet 54i side and the portion of the air outlet 54o. The bypass passage 54b is formed so that both ends open to the inner peripheral surface of the flowmeter 54 that defines the main passage 54p, and communicates with the main passage 54p at the air inlet 54i side of the small diameter passage 54n and the air outlet 54o side of the small diameter passage 54n. A sensor element 54e including, for example, a heater and two temperature sensors is disposed in the bypass passage 54b.

[0029] Furthermore, the flowmeter 54 includes a straightening plate 54r arranged closer to the air inlet 54i than the bypass passage 54b. The straightening plate 54r is a porous plate made of, for example, stainless steel, having a large number of small holes arranged at equal intervals in a matrix. The straightening plate 54r is also coated with glass or fluorine to suppress adhesion of ammonium sulfate. The straightening plate 54r equalizes the flow rate of air flowing from the air inlet 54i into the main passage 54p throughout the radial direction (cross section) of the main passage 54p. As shown in Figs. 1 and 2, the flowmeter 54 is arranged downstream of the ammonium sulfate capture tank 55 and upstream of the power generation module 20 (fuel cell stack 21) and the air supply pipe 53 in the air supply direction so that the main passage 54p extends in the vertical direction. In this embodiment, the flowmeter 54 is arranged in or near the auxiliary machinery room whose interior is ventilated in order to suppress the formation of a temperature distribution in the vertical direction in the main passage 54p, etc. Furthermore, the flow meter 54 may be provided with a heat insulating material or a heat shield plate (not shown).

[0030] As described above, the air supply system 50 of the fuel cell system 10 includes the ammonium sulfate capture tank 55 that captures ammonium sulfate in the air supplied to the fuel cell stack 21 of the power generation module 20, and the first air pipe 56 for introducing air from the air pump 52 into the internal passage 55p of the ammonium sulfate capture tank 55. The internal passage 55p of the ammonium sulfate capture tank 55 has a cross-sectional area that is at least twice as large as the cross-sectional area of ​​the first air pipe 56. This reduces the flow rate of the air flowing from the first air pipe 56 into the ammonium sulfate capture tank 55 by at least half, and the kinetic energy of the air in the internal passage 55p is significantly reduced, so that the air can be convected in the ammonium sulfate capture tank 55 as shown in FIG. 2. As a result, the ammonium sulfate having a high density is deposited in the ammonium sulfate capture tank 55 (bottom 55b), and the ammonium sulfate in the air supplied from the air supply system 50 to the fuel cell stack 21 can be effectively removed.

[0031] The air supply system 50 also includes an air pump 52 that draws in and pumps out air, and a second air pipe 57 that discharges air from the ammonium sulfate capture tank 55 to the air supply pipe 53 side (fuel cell stack 21 side). The ammonium sulfate capture tank 55 is disposed between the air pump 52 and the air supply pipe 53 (fuel cell stack 21) so that an internal passage 55p extends in the vertical direction. The first air pipe 56 is connected to the discharge port of the air pump 52, and is connected to the ammonium sulfate capture tank 55 above the bottom 55b of the internal passage 55p and below the second air pipe 57 so as to communicate laterally with the internal passage 55p.

[0032] That is, in the fuel cell system 10, the first air pipe 56 from the air pump 52 and the internal passage 55p of the ammonium sulfate capture tank 55 intersect in a substantially T-shape, and the internal passage 55p extends in the vertical direction. This promotes air convection in the ammonium sulfate capture tank 55, and allows high-density ammonium sulfate to accumulate at the bottom 55b of the internal passage 55p. In addition, when water vapor flows back from the power generation module 20 (fuel cell stack 21) to the air supply system 50 in response to a shutdown of the fuel cell system 10, the water condensed between the power generation module 20 and the ammonium sulfate capture tank 55 can be accumulated at the bottom 55b of the internal passage 55p (see the two-dot chain line in FIG. 2). This allows the accumulated ammonium sulfate to be deliquesced by the water accumulated at the bottom 55b, and makes it possible to effectively prevent the water from flowing into the air pump 52 (for example, an air bearing supporting the main shaft) via the first air pipe 56.

[0033] In the fuel cell system 10, the second air pipe 57 on the air supply pipe 53 side intersects with the internal passage 55p of the ammonium sulfate capture tank 55 in a substantially T-shape, but is not limited to this. That is, the second air pipe 57 may be connected to the upper part of the ammonium sulfate capture tank 55 so as to intersect with the internal passage 55p of the ammonium sulfate capture tank 55 in a substantially L-shape. In addition, the axial length of the internal passage 55p of the ammonium sulfate capture tank 55 (the height from the junction with the first air pipe 56 to the junction with the second air pipe 57) should be set to a certain degree of length so that the ammonium sulfate capture performance is sufficiently ensured and the inflow of water vapor (condensed water) from the fuel cell stack 21 side to the air pump 52 is effectively suppressed.

[0034] Furthermore, the air supply system 50 includes a flowmeter 54 for detecting the flow rate of air supplied to the fuel cell stack 21, and the flowmeter 54 is disposed between the ammonium sulfate capture tank 55 and the air supply pipe 53 (fuel cell stack 21) so as to allow air to flow vertically. This allows a large amount of water vapor to flow through the flowmeter 54 when water vapor flows back from the power generation module 20 side to the air supply system 50, thereby allowing ammonium sulfate attached to the flowmeter 54's straightening plate 54r and the like to be deliquesced well. In addition, condensation of water vapor within the flowmeter 54 can be suppressed, thereby reducing adverse effects on flow rate detection due to water contact with the flowmeter 54. However, the flowmeter 54 may be disposed horizontally between the ammonium sulfate capture tank 55 and the air supply pipe 53 (fuel cell stack 21) so as to allow air to flow substantially horizontally.

[0035] The flowmeter 54 includes an air inlet 54i on the ammonium sulfate capture tank 55 (air pump 52) side, an air outlet 54o on the air supply pipe 53 side (fuel cell stack 21 side), a main passage 54p connecting the air inlet 54i and the air outlet 54o, a bypass passage 54b branched off from the main passage 54p, a sensor element 54e arranged in the bypass passage 54b, and a straightening plate 54r having a plurality of holes and arranged closer to the air inlet 54i than the bypass passage 54b to equalize the flow rate of air flowing from the air inlet 54i into the main passage 54p. When air is supplied from the ammonium sulfate capture tank 55 (air pump 52) to the air inlet 54i, the flowmeter 54 can smoothly allow a portion of the air supplied to the air inlet 54i to flow into the bypass passage 54b. In addition, when water vapor flows back from the power generation module 20 side to the air outlet 54o, the water vapor that has flowed into the air outlet 54o is restricted from flowing into the bypass passage 54b, and more water vapor can be guided to the straightening plate 54r.

[0036] That is, the main passage 54p of the flowmeter 54 includes a small-diameter passage 54n having a small diameter (small passage cross-sectional area) and a short length in the center in the air flow direction, and the bypass passage 54b communicates with the main passage 54p at the air inlet 54i side of the small-diameter passage 54n and the air outlet 54o side of the small-diameter passage 54n. Furthermore, the flowmeter 54 includes a straightening plate 54r arranged on the air inlet 54i side of the bypass passage 54b that equalizes the flow speed of air flowing from the air inlet 54i to the main passage 54p in the entire radial direction (cross section) of the main passage 54p. Therefore, when air is supplied from the ammonium sulfate capture tank 55 (air pump 52) to the air inlet 54i, it is possible to make the flow speed of air passing through the small-diameter passage 54n of the main passage 54p approximately the same as the flow speed of air near the inner circumferential surface of the flowmeter 54 that defines the main passage 54p, and the inflow of air into the bypass passage 54b can be promoted. Furthermore, no straightening vane is disposed on the air outlet 54o side of the flowmeter 54. Therefore, when water vapor flows back from the power generation module 20 side to the air outlet 54o, the flow rate of the water vapor near the inner circumferential surface of the flowmeter 54 that defines the main passage 54p is lower than the water vapor passing through the small diameter passage 54n, so that the water vapor can be effectively prevented from flowing into the bypass passage 54b.

[0037] As a result, in the fuel cell system 10, it is possible to ensure good flow rate detection accuracy by the flowmeter 54 (sensor element 54e), while deliquescing the ammonium sulfate attached to the rectifying plate 54r by water vapor flowing back from the power generation module 20. Furthermore, since the rectifying plate 54r is coated with glass or fluorine, it is possible to effectively prevent the adhesion of ammonium sulfate to the rectifying plate 54r, i.e., the clogging of the rectifying plate 54r.

[0038] It goes without saying that the invention of this disclosure is not limited to the above embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0039] The present disclosure is applicable to the fuel cell system manufacturing industry and the like. [Explanation of symbols]

[0040] 10 fuel cell system, 20 power generation module, 21 fuel cell stack, 50 air supply system, 51 air filter, 52 air pump, 53 air supply pipe, 54 flow meter, 54b bypass passage, 54e sensor element, 54i air inlet, 54n small diameter passage, 54o air outlet, 54p main passage, 54r straightening plate, 55 ammonium sulfate capture tank, 55b bottom, 55p internal passage, 55s ceiling, 56 first air pipe, 57 second air pipe.

Claims

1. A fuel cell system including a fuel cell that generates electricity by an electrochemical reaction between an anode gas and a cathode gas, and an air supply system that supplies air as the cathode gas to the fuel cell, an ammonium sulfate capture tank included in the air supply system for capturing ammonium sulfate in the air supplied to the fuel cell; an air pipe for introducing air into the internal passage of the ammonium sulfate capture tank; A fuel cell system, wherein the cross-sectional area of ​​the internal passage of the ammonium sulfate capture tank is at least twice the cross-sectional area of ​​the air pipe.

2. 2. The fuel cell system according to claim 1, the air supply system includes an air pump that draws in and pressure-feeds air, and a second air pipe that discharges air from the ammonium sulfate capture tank to the fuel cell side; the ammonium sulfate capture tank is disposed between the air pump and the fuel cell such that the internal passage extends in a vertical direction; The air piping is connected to the outlet of the air pump and is connected to the ammonium sulfate capture tank so as to communicate laterally with the internal passage above the bottom of the internal passage and below the second air piping.

3. 3. The fuel cell system according to claim 1, the air supply system includes a flow meter that detects a flow rate of the air supplied to the fuel cell; A fuel cell system in which the flow meter is disposed between the ammonium sulfate capture tank and the fuel cell so as to allow air to flow vertically.

4. 4. The fuel cell system according to claim 3, The flow meter includes: An air inlet on the ammonium sulfate capture tank side; an air outlet on the fuel cell side; a main passage communicating the air inlet and the air outlet; a bypass passage branched off from the main passage; A sensor element disposed in the bypass passage; a straightening plate having a plurality of holes and disposed closer to the air inlet than the bypass passage, for uniforming the flow rate of air flowing from the air inlet into the main passage.

Images