Fuel Cell Systems

Abstract

To provide a fuel cell system capable of suppressing condensation of water vapor generated in a booster lower than heretofore.SOLUTION: A fuel cell system 100 comprises: a solid polymer-type fuel cell 1 for generating power using fuel gas and oxidant gas; a fuel gas supply path 2 for supplying the fuel gas to an anode inlet 1A of the fuel cell 1; a recycle gas path 3 for returning anode off-gas discharged from an anode outlet 1B of the fuel cell 1 to the fuel gas supply path 2; a booster 5 provided, on the fuel gas supply path 2, between the anode inlet 1A and a junction 4 at which the fuel gas supply path 2 and the recycle gas path 3 join; and a discharge path 8 for discharging impurities mixed in the anode off-gas to the outside.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] In a fuel cell system, a configuration has been proposed in which fuel gas (anode off-gas) not used in power generation by the fuel cell is returned to the anode of the fuel cell to be reused (recycled) (see, for example, Patent Document 1). This improves the power generation efficiency of the fuel cell system compared to a configuration in which the anode off-gas is not recycled.

[0003] In Patent Document 1, a recycled gas path for returning the anode off-gas discharged from the anode of the fuel cell to the fuel cell is provided with a circulator (booster) that pressurizes the anode off-gas to the anode of the fuel cell, and a gas-liquid separator that separates moisture in the anode off-gas from the anode off-gas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-52948 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional example, the problem of condensation of water vapor generated in the circulator (booster) has not been fully considered.

[0006] One aspect of the present disclosure has been made in view of the above circumstances, and provides a fuel cell system that can reduce condensation of water vapor generated in a booster more than ever before. [Means for solving the problem]

[0007] In order to solve the above problems, a fuel cell system of one embodiment of the present disclosure includes a solid polymer fuel cell that generates electricity using a fuel gas and an oxidant gas, a fuel gas supply path for supplying the fuel gas to an anode inlet of the fuel cell, a recycled gas path for returning anode off-gas discharged from an anode outlet of the fuel cell to the fuel gas supply path, a booster provided in the fuel gas supply path between the anode inlet and a junction where the fuel gas supply path and the recycled gas path join, and a discharge path for discharging impurities mixed in the anode off-gas to the outside. Effect of the Invention

[0008] A fuel cell system according to one aspect of the present disclosure has an advantage that condensation of water vapor generated in the booster can be reduced more than in the past. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a fuel cell system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a fuel cell system according to the second embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of a fuel cell system according to the third embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a fuel cell system according to the fourth embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of a fuel cell system according to a first modified example of the fourth embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a fuel cell system according to a second modified example of the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The problem of condensation of water vapor generated in the booster was thoroughly investigated, and the following findings were obtained:

[0011] The amount of saturated water vapor contained in a certain volume depends on temperature and is independent of pressure, and the amount of water vapor contained per unit volume of anode off-gas increases as the pressure increases when the temperature is constant. Therefore, when the anode off-gas is pressurized by the booster, the water vapor in the anode off-gas may condense into water.

[0012] In Patent Document 1, the high-humidity anode off-gas flows into the booster while maintaining its humidity. Therefore, condensation occurs when the anode off-gas is pressurized, and the condensation accumulates in the booster. This may cause the flow rate of the anode off-gas to become unstable due to clogging of the flow path of the booster caused by the condensation, and may cause the booster to deteriorate in performance or break down due to the condensation.

[0013] Therefore, the fuel cell system of the first aspect of the present disclosure has been devised based on this knowledge, and comprises a solid polymer fuel cell that generates electricity using a fuel gas and an oxidant gas, a fuel gas supply path for supplying fuel gas to the anode inlet of the fuel cell, a recycled gas path for returning anode off-gas discharged from the anode outlet of the fuel cell to the fuel gas supply path, a booster provided in the fuel gas supply path between the anode inlet and the junction where the fuel gas supply path and the recycled gas path join, and an exhaust path for exhausting impurities mixed in the anode off-gas to the outside.

[0014] According to this configuration, the fuel cell system of this embodiment can reduce condensation of water vapor generated in the booster more than in the past. Specifically, a booster is provided in the fuel gas supply path between the junction and the anode inlet, and the low-humidity fuel gas before flowing into the booster and the high-humidity anode off-gas are mixed at the junction. This can reduce the humidity of the mixed gas flowing into the booster. This can reduce the condensation of water vapor in the booster even when the mixed gas is pressurized in the booster. This can reduce the possibility that the flow rate of the mixed gas becomes unstable due to clogging of the booster caused by condensed water. In addition, if the booster becomes corroded or dirty due to condensed water, the performance of the booster may deteriorate or break down, but the fuel cell system of this embodiment can reduce such a possibility.

[0015] Furthermore, the fuel cell system of this embodiment can discharge impurities mixed in the anode off-gas to the outside by, for example, opening a purge valve provided in the exhaust path at an appropriate time, thereby making it possible to appropriately restore the hydrogen concentration of the anode off-gas.

[0016] A fuel cell system according to a second aspect of the present disclosure may further include a flow rate controller provided in the recycled gas path for adjusting the flow rate of the anode off-gas in the fuel cell system according to the first aspect.

[0017] With this configuration, resistance can be generated in the flow of fuel gas from the junction toward the anode outlet of the fuel cell, and the flow of the fuel gas can be appropriately adjusted, so that the fuel gas can be smoothly sent from the junction to the booster.

[0018] A fuel cell system according to a third aspect of the present disclosure is the fuel cell system according to the first or second aspect, wherein the booster is provided above the junction.

[0019] With this configuration, the fuel gas supply path from the junction toward the gas inlet of the booster can be extended with an upward gradient, so that even if water vapor in the anode off-gas condenses into water, the condensed water can be prevented from flowing into the gas inlet of the booster.

[0020] A fuel cell system according to a fourth aspect of the present disclosure may be a fuel cell system according to any one of the first to third aspects, further comprising a gas-liquid separator connected to the recycled gas path or the fuel gas supply path downstream of the above-mentioned junction.

[0021] According to this configuration, the condensed water generated when the temperature of the highly humid anode off-gas is reduced can be appropriately treated by the gas-liquid separator.

[0022] Hereinafter, an embodiment of the present disclosure will be described with reference to the attached drawings. The embodiments described below are all examples of the above aspects. Therefore, the shapes, materials, components, and the arrangement and connection forms of the components shown below are merely examples, and do not limit the above aspects unless otherwise stated in the claims. In addition, among the components below, components that are not described in the independent claims showing the highest concept of this aspect are described as optional components. In addition, in the drawings, the description of components with the same reference numerals may be omitted. In order to make the drawings easier to understand, each component is shown diagrammatically, and the shape and dimensional ratio may not be accurately shown.

[0023] (First embodiment) FIG. 1 is a diagram showing an example of a fuel cell system according to a first embodiment.

[0024] In the example shown in FIG. 1, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a discharge path 8, and a purge valve 9.

[0025] The fuel cell 1 generates power using a fuel gas and an oxidant gas. The fuel cell 1 may be of any type. In the fuel cell system 100 of this embodiment, the fuel cell 1 is described using a polymer electrolyte fuel cell (PEFC) as an example, but is not limited to this. For example, a solid oxide fuel cell (SOFC) may be used.

[0026] The fuel gas supply path 2 is a flow path for supplying fuel gas to the anode inlet 1A of the fuel cell 1. That is, the downstream end of the fuel gas supply path 2 is connected to the anode inlet 1A of the fuel cell 1, and the upstream end is connected to a fuel gas supply source (not shown). The fuel gas supply source has a predetermined supply source pressure, and examples of the fuel gas supply source include a fuel gas infrastructure and a fuel gas cylinder. Examples of the fuel gas include hydrogen gas. In this case, the anode off-gas is off-hydrogen gas that has not been used in the fuel cell 1.

[0027] The recycled gas path 3 is a flow path for returning the anode off-gas discharged from the anode outlet 1B of the fuel cell to the fuel gas supply path 2. In other words, the upstream end of the recycled gas path 3 is connected to the anode outlet 1B of the fuel cell, and the downstream end is connected to the fuel gas supply path 2.

[0028] The booster 5 is provided in the fuel gas supply path 2 downstream of the junction 4 where the fuel gas supply path 2 and the recycled gas path 3 join in the flow direction of the fuel gas. In other words, the booster 5 is provided in the fuel gas supply path 2 between the junction 4 and the anode inlet 1A. The booster 5 is a device that pumps and delivers a mixed gas containing anode off-gas and fuel gas flowing through the fuel gas supply path 2. The booster 5 may have any configuration as long as it can pump and deliver the mixed gas. Examples of the booster 5 include a diaphragm pump, a rotary pump, and a reciprocating pump.

[0029] The junction 4 includes a flow path through which the anode off-gas, the fuel gas, and the mixed gas flow. An example of a flow path member constituting such a flow path is a T-shaped joint.

[0030] The exhaust path 8 is a path for discharging impurities mixed in the anode off-gas to the outside. Since the gas passing through the exhaust path 8 is flammable gas, the exhaust path 8 is generally made of a piping made of a flame-retardant material (for example, a metal piping such as a stainless steel piping), but is not limited thereto.

[0031] During power generation by the fuel cell 1, the anode off-gas circulates from the anode outlet 1B back to the anode inlet 1A of the fuel cell 1 until it is used to generate power in the fuel cell 1.

[0032] Therefore, the fuel cell system 100 of this embodiment includes an exhaust path 8 that branches off from the circulation path and communicates with the atmosphere, and a purge valve 9 provided in the exhaust path 8. As the purge valve 9, for example, a solenoid valve can be used, but is not limited thereto.

[0033] As a result, it is possible to reduce the concentration of impurities mixed into the anode off-gas. Then, the hydrogen concentration in the anode off-gas can be appropriately restored. Specifically, while the purge valve 9 is closed, the anode off-gas circulates from the anode outlet 1B of the fuel cell 1 back to the anode inlet 1A until it is used for power generation by the fuel cell 1. Then, while the anode off-gas circulates through the circulation path, impurities other than the fuel gas (hydrogen gas) increase over time in the anode off-gas. As an example of the impurity, since air flows through the cathode of the fuel cell 1, nitrogen gas leaking from the cathode to the anode through the electrolyte membrane can be exemplified. When the impurities mixed into the anode off-gas increase, the hydrogen concentration in the anode off-gas decreases, so that during power generation by the fuel cell 1, the purge valve 9 is temporarily opened at an appropriate time to release (purge) the purge gas containing impurities from the circulation path to the atmosphere.

[0034] The downstream end of the discharge path 8 is open to the atmosphere. The upstream end of the discharge path 8 may be connected to any location as long as it is a circulation path through which the anode off-gas circulates.

[0035] For example, the upstream end of the discharge path 8 may be connected to the recycled gas path 3. This allows the purge gas containing impurities to be discharged (purged) from the recycled gas path 3 to the atmosphere by temporarily opening the purge valve 9.

[0036] In addition, the upstream end of the discharge path 8 may be connected to the fuel gas supply path 2 between the junction 4 and the gas inlet of the booster 5. In this way, by temporarily opening the purge valve 9, the purge gas containing impurities can be discharged (purged) from the fuel gas supply path 2 to the atmosphere.

[0037] In addition, the upstream end of the discharge path 8 may be connected to the fuel gas supply path 2 between the gas outlet of the booster 5 and the anode inlet 1A. This allows the purge gas containing impurities to be discharged (purged) from the fuel gas supply path 2 to the atmosphere by temporarily opening the purge valve 9.

[0038] In the fuel cell system 100 of this embodiment, the upstream end of the discharge path 8 is connected to the recycled gas path 3. This makes it possible to appropriately suppress the release of fuel gas with a high hydrogen concentration when the purge valve 9 is temporarily opened to release (purge) the purge gas containing impurities from the recycled gas path 3 into the atmosphere.

[0039] As described above, the fuel cell system 100 of this embodiment can reduce the condensation of water vapor generated in the booster 5 more than in the past.

[0040] Specifically, the amount of saturated water vapor contained in a certain volume depends on temperature and is independent of pressure, and the amount of water vapor contained per unit volume of anode off-gas increases with increasing pressure at a constant temperature, so that water vapor in the anode off-gas may condense into water when the anode off-gas is pressurized by booster 5. At this time, the higher the humidity of the anode off-gas, the greater the amount of water vapor in the anode off-gas, making it more likely that condensed water will occur in booster 5.

[0041] Therefore, in the fuel cell system 100 of this embodiment, the booster 5 is provided in the fuel gas supply path 2 between the junction 4 and the anode inlet 1A, and the low-humidity fuel gas before flowing into the booster 5 and the high-humidity anode off-gas are mixed in the junction 4. This makes it possible to reduce the humidity of the mixed gas flowing into the booster 5. This makes it possible to reduce the condensation of water vapor in the booster 5 even when the mixed gas is pressurized in the booster 5. This reduces the possibility that the flow rate of the mixed gas becomes unstable due to clogging of the flow path of the booster 5 caused by condensed water. In addition, if the booster 5 becomes corroded or dirty due to condensed water, the booster 5 may deteriorate in performance or break down, but the fuel cell system 100 of this embodiment can reduce such a possibility.

[0042] Furthermore, the fuel cell system 100 of this embodiment can discharge impurities mixed in the anode off-gas to the outside by timely opening the purge valve 9 provided in the exhaust path 8. This makes it possible to appropriately restore the hydrogen concentration in the anode off-gas.

[0043] Second embodiment FIG. 2 is a diagram showing an example of a fuel cell system according to the second embodiment.

[0044] In the example shown in FIG. 2, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a flow rate controller 6, a discharge path 8, and a purge valve 9.

[0045] The fuel cell 1, fuel gas supply path 2, recycled gas path 3, booster 5, exhaust path 8 and purge valve 9 are similar to those in the first embodiment, and therefore description thereof will be omitted.

[0046] Since the fuel gas flowing into the junction 4 tends to flow in the direction where the pressure loss in the flow path is small, for example, if the pressure loss in the booster 5 on the fuel gas supply path 2 is large, the fuel gas may not flow easily from the junction 4 to the booster 5, and the fuel gas may flow from the junction 4 toward the anode outlet 1B of the fuel cell 1. Then, if the upstream end of the exhaust path 8 is connected to the recycled gas path 3, the fuel gas from the junction 4 may be exhausted to the atmosphere via the exhaust path 8.

[0047] Therefore, the fuel cell system 100 of this embodiment is provided with a flow rate controller 6 that adjusts the flow rate of the anode off-gas.

[0048] The flow rate controller 6 may have any configuration as long as it can adjust the flow rate of the anode off-gas. Here, the adjustment means increasing or decreasing the flow rate of the anode off-gas so that an appropriate amount of the anode off-gas flows through the recycled gas path 3, or stopping the flow of the anode off-gas through the recycled gas path 3, etc.

[0049] For example, a flow rate control valve that adjusts the flow rate of the anode off-gas can be used as the flow rate controller 6. Also, a check valve that prohibits the flow of fuel gas from the junction 4 toward the anode outlet 1B, a mechanism that increases the pressure loss in the recycled gas path 3, etc. can be used as the flow rate controller 6. Examples of the latter include a throttle mechanism that partially narrows the diameter of the piping that constitutes the recycled gas path 3, and an orifice provided in this piping.

[0050] As described above, in the fuel cell system 100 of this embodiment, the flow rate controller 6 can generate resistance to the flow of fuel gas from the junction 4 toward the anode outlet 1B of the fuel cell 1, and thus the flow of such fuel gas can be appropriately adjusted. Specifically, the flow rate of the anode off-gas toward the junction 4 can be adjusted, and at the same time, the backflow of fuel gas from the junction 4 to the recycled gas path 3 can be suppressed. As a result, the fuel gas can be smoothly sent from the junction 4 to the booster 5.

[0051] Other than the above-mentioned features, the fuel cell system 100 of this embodiment may be configured similarly to the fuel cell system 100 of the first embodiment.

[0052] Third embodiment Fig. 3 is a diagram showing an example of a fuel cell system according to a third embodiment. In Fig. 3, "upper" and "lower" are shown, and gravity acts from top to bottom.

[0053] In the example shown in FIG. 3, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a discharge path 8, and a purge valve 9.

[0054] The fuel cell system 100 of this embodiment is similar to the fuel cell system 100 of the first embodiment, except for the vertical positional relationship between the junction 4 and the booster 5.

[0055] The fuel cell 1 generates water vapor while generating power. Therefore, the anode off-gas may be discharged from the anode outlet 1B of the fuel cell 1 in a wet state. When the high humidity anode off-gas passes through the recycled gas path 3, the temperature of the anode off-gas may drop below the dew point due to heat radiation from the anode off-gas via the recycled gas path 3. In addition, when the high temperature recycled gas and the low temperature fuel gas join at the joining section 4, the temperature of the anode off-gas may drop below the dew point due to the drop in temperature of the anode off-gas. Furthermore, when the operation of the fuel cell system 100 is stopped, the anode off-gas may be cooled by heat radiation from the piping. Then, the water vapor in the anode off-gas may condense into water. In this case, if the booster 5 is provided below the joining section 4, the condensed water generated above is likely to flow into the gas inlet of the booster 5 by gravity.

[0056] Therefore, in the fuel cell system 100 of this embodiment, the booster 5 is provided above the junction 4. Here, "above" refers to a case where gravity acts from top to bottom. This allows the fuel gas supply path 2 from the junction 4 toward the gas inlet of the booster 5 to be extended with an upward gradient. Then, even if the water vapor in the anode off-gas condenses into water, the condensed water can be prevented from flowing into the gas inlet of the booster 5. This reduces the possibility that the flow rate of the mixed gas becomes unstable due to clogging of the flow path of the booster 5 caused by the condensed water. In addition, if the corrosion and dirt of the booster 5 progresses due to the condensed water, the performance deterioration or failure of the booster 5 may occur, but the fuel cell system 100 of this embodiment can reduce such a possibility. Note that, as in the example shown in FIG. 3, the junction 4 may be provided above the anode outlet 1B. As a result, the condensed water generated above the anode outlet 1B flows to the anode outlet 1B.

[0057] Other than the above-mentioned features, the fuel cell system 100 of this embodiment may be configured similarly to the fuel cell systems 100 of the first and second embodiments.

[0058] (Fourth embodiment) FIG. 4 is a diagram showing an example of a fuel cell system according to the fourth embodiment.

[0059] In the example shown in FIG. 4, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a gas-liquid separator 7A, and a discharge path 8. The fuel cell 1, the fuel gas supply path 2, the recycled gas path 3 and the booster 5 are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0060] The fuel cell 1 generates water vapor while generating power. Therefore, the anode off-gas may be discharged from the anode outlet 1B of the fuel cell 1 in a wet state. When the highly humid anode off-gas passes through the recycled gas path 3, the temperature of the anode off-gas may drop below the dew point due to heat dissipation from the anode off-gas through the recycled gas path 3. In addition, when the high-temperature recycled gas and the low-temperature fuel gas join at the joining portion 4, the temperature of the anode off-gas may drop below the dew point due to the drop in the temperature of the anode off-gas. This may cause the water vapor in the anode off-gas to condense into water.

[0061] Therefore, the fuel cell system 100 of this embodiment is provided with a gas-liquid separator 7A that separates the condensed water in the anode off-gas from the anode off-gas.

[0062] In the fuel cell system 100 of this embodiment, the gas-liquid separator 7A is connected to the recycled gas path 3 via a branch path.

[0063] The gas-liquid separator 7A may be, for example, a tank or a sealing valve provided in a branch path branching off from the recycled gas path 3 between the anode outlet 1B of the fuel cell 1 and the junction 4.

[0064] When the gas-liquid separator 7A is the former tank, for example, the anode off-gas is sealed with water by connecting the branch path to the lower end of the tank. When the water in the tank becomes nearly full, the water is drained to the outside through an appropriate drain outlet at the upper end of the tank.

[0065] In the case where the gas-liquid separator 7A is the latter type of sealing valve, when the water in the branch path becomes nearly full, the sealing valve is temporarily opened to drain the water to the outside.

[0066] 4, the branch path connected to the gas-liquid separator 7A may be a discharge path 8. In this case, the gas-liquid separator 7A has the function of a purge valve 9. That is, impurities mixed in the anode off-gas are discharged to the outside via the drain port of the gas-liquid separator 7A at the same time as the condensed water is discharged.

[0067] As described above, the fuel cell system 100 of this embodiment can appropriately treat the condensed water generated by a drop in temperature of the highly humid anode off-gas in the gas-liquid separator 7A. For example, even if condensed water is generated from the anode off-gas due to a drop in temperature of the anode off-gas discharged from the anode outlet 1B of the fuel cell 1, the gas-liquid separator 7A can separate the condensed water from the anode off-gas. This can prevent clogging of the recycle gas path 3 caused by the condensed water. In addition, the inflow of the condensed water into the anode outlet 1B and the booster 5 can be prevented.

[0068] Other than the above-mentioned features, the fuel cell system 100 of this embodiment may be configured similarly to the fuel cell system 100 of any of the first to third embodiments.

[0069] (First Modification) FIG. 5 is a diagram showing an example of a fuel cell system according to a first modified example of the fourth embodiment.

[0070] 5, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a gas-liquid separator 7B, an exhaust path 8, and a purge valve 9. The fuel cell 1, the fuel gas supply path 2, the recycled gas path 3, the booster 5, the exhaust path 8, and the purge valve 9 are similar to those in the first embodiment, and therefore description thereof will be omitted.

[0071] In the fuel cell system 100 of this modified example, the gas-liquid separator 7B is connected to the fuel gas supply path 2 between the junction 4 and the gas inlet of the booster 5 via a branch path.

[0072] The gas-liquid separator 7B may be, for example, a tank or a sealing valve provided in a branch path branching off from the fuel gas supply path 2 between the junction 4 and the gas inlet of the booster 5. Note that these tanks and sealing valves are similar to those in the fourth embodiment, and therefore detailed description thereof will be omitted.

[0073] As described above, the fuel cell system 100 of this modified example can appropriately process condensed water generated by a drop in temperature of a mixed gas containing a highly humid anode off-gas and a fuel gas. For example, even if condensed water is generated from the mixed gas (anode off-gas) due to a drop in the temperature of the mixed gas, the gas-liquid separator 7B can separate the condensed water from the mixed gas. This can prevent clogging of the fuel gas supply path 2 caused by the condensed water. In addition, the inflow of condensed water into the anode outlet 1B and the booster 5 can be prevented.

[0074] Other than the above-mentioned features, the fuel cell system 100 of this modified example may be configured similarly to the fuel cell system 100 of any one of the first to third embodiments.

[0075] (Second Modification) FIG. 6 is a diagram showing an example of a fuel cell system according to a second modified example of the fourth embodiment.

[0076] 5, the fuel cell system 100 includes a fuel cell 1, a fuel gas supply path 2, a recycled gas path 3, a booster 5, a gas-liquid separator 7C, an exhaust path 8, and a purge valve 9. The fuel cell 1, the fuel gas supply path 2, the recycled gas path 3, the booster 5, the exhaust path 8, and the purge valve 9 are similar to those in the first embodiment, and therefore description thereof will be omitted.

[0077] In the fuel cell system 100 of this modified example, the gas-liquid separator 7C is connected to the fuel gas supply path 2 between the gas outlet of the booster 5 and the anode inlet 1A of the fuel cell 1 via a branch path.

[0078] The gas-liquid separator 7C may be, for example, a tank or a sealing valve provided in a branch path branching off from the fuel gas supply path 2 between the gas outlet of the booster 5 and the anode inlet 1A of the fuel cell 1. Note that these tanks and sealing valves are similar to those in the fourth embodiment, and therefore detailed description thereof will be omitted.

[0079] As described above, the fuel cell system 100 of this modified example can appropriately process condensed water generated by a drop in temperature of a mixed gas containing a highly humid anode off-gas and a fuel gas, and condensed water generated by boosting the mixed gas by the booster 5. For example, even if condensed water is generated from the mixed gas (anode off-gas) due to a drop in the temperature of the mixed gas, the gas-liquid separator 7C can separate the condensed water from the mixed gas. This can prevent clogging of the fuel gas supply path 2 caused by the condensed water. In addition, the inflow of condensed water into the anode inlet 1A and the booster 5 can be prevented.

[0080] Other than the above-mentioned features, the fuel cell system 100 of this modified example may be configured similarly to the fuel cell system 100 of any one of the first to third embodiments.

[0081] Although not shown in FIGS. 1 to 6, devices necessary for power generation by the fuel cell 1 are provided as appropriate.

[0082] For example, the fuel cell system 100 is provided with an oxidant gas supplier that supplies an oxidant gas to the cathode of the fuel cell 1.

[0083] In this case, the oxidant gas supplier may have any configuration as long as it can supply the oxidant gas to the cathode. Examples of the oxidant gas supplier include air blowers such as blowers and fans.

[0084] In addition, when the supply pressure of the fuel gas supply source is higher than the supply pressure (fuel gas supply pressure) required for the fuel cell system 100, a governor or the like may be provided in the fuel gas supply path 2 to reduce the fuel gas pressure to a constant supply pressure.

[0085] Furthermore, a humidifier for humidifying the fuel gas may be provided between the booster 5 and the anode inlet 1A on the fuel gas supply path 2. The humidifier may include a water tank or a heat exchanger.

[0086] The first to fourth embodiments and the first and second modifications of the fourth embodiment may be combined with each other as long as they do not exclude each other.

[0087] From the above description, many modifications and other embodiments of the present disclosure will be apparent to those skilled in the art.

[0088] Therefore, the above description should be construed as merely illustrative and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the present disclosure, and the details of its structure and / or function may be substantially changed without departing from the spirit of the present disclosure. [Industrial Applicability]

[0089] One aspect of the present disclosure can reduce condensation of water vapor generated in a booster more than ever before, and can be used, for example, in fuel cell systems used in home cogeneration systems and power sources for electric vehicles. [Explanation of symbols]

[0090] 1:Fuel cell 1A: Anode inlet 1B: Anode outlet 2: Fuel gas supply route 3: Recycle gas route 4: Junction 5: Booster 6: Flow controller 7A: Gas-liquid separator 7B: Gas-liquid separator 7C: Gas-liquid separator 8: Discharge route 9: Purge valve 100: Fuel cell system

Claims

1. a polymer electrolyte fuel cell that generates electricity using a fuel gas and an oxidant gas; a fuel gas supply path for supplying the fuel gas to an anode inlet of the fuel cell; a single recycle gas path for returning an anode off-gas discharged from an anode outlet of the fuel cell to the fuel gas supply path; a booster provided in the fuel gas supply path between a junction where the fuel gas supply path and the single recycled gas path join and the anode inlet; an exhaust path for exhausting impurities mixed in the anode off-gas to the outside; a flow rate controller that is provided in the single recycled gas path upstream of the junction and adjusts a flow rate of the anode off-gas toward the junction; The flow rate controller is a flow rate adjustment valve, a throttle mechanism, or an orifice.

2. a polymer electrolyte fuel cell that generates electricity using a fuel gas and an oxidant gas; a fuel gas supply path for supplying the fuel gas to an anode inlet of the fuel cell; a recycle gas passage for returning an anode off-gas discharged from an anode outlet of the fuel cell to the fuel gas supply passage; a booster provided in the fuel gas supply path between a junction where the fuel gas supply path and the recycled gas path join and the anode inlet; an exhaust path for exhausting impurities mixed in the anode off-gas to the outside; a gas-liquid separator connected to the fuel gas supply path downstream of the junction and upstream of the booster.

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