JP2018037328A - Fuel cell system and operation method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a combustor to operate more accurately in a fuel cell system including a combustor for generating combustion gas for driving a turbine. A turbine 22 for driving a compressor 201 is connected to a cathode gas discharge passage 122 of a combustion battery 10, and a combustor 34 for generating combustion gas for driving the turbine 22 is provided in the cathode gas discharge passage 122. To wear. The gas-liquid separator 32 is installed on the upstream side of the combustor 34 in the cathode gas exhaust passage 122, and the combustor 34 is installed on the upstream side of the gas-liquid separator 32 in the cathode gas exhaust passage 122 by the fuel supply unit. To supply the fuel to be burned. [Selection diagram] Figure 1

Description

  The present invention relates to a fuel cell system that drives a turbine by combustion gas generated by a combustor and an operation method thereof.

  A fuel cell system comprising a compressor in a cathode gas supply passage of a fuel cell, and supplying an oxidant to the fuel cell through the compressor, and a turbine connected to the cathode gas discharge passage and driving the compressor by the turbine It has been known. As such a fuel cell system, in addition to the compressor and the turbine, a combustor is interposed in the cathode gas discharge passage, and the combustion gas generated by the combustor is supplied to the turbine to drive the turbine. Things are also known.

  Patent Document 1 describes a fuel cell system including a gas-liquid separator in each of a cathode offgas line and an anode offgas line of a fuel cell. The cathode off-gas was introduced into the gas-liquid separator of the cathode off-gas line, and the cathode off-gas from which moisture was removed was allowed to flow into the mixer, and the anode off-gas was introduced into the gas-liquid separator of the anode off-gas line to remove moisture. An anode off gas is flowed into the mixer. A mixed gas of cathode offgas and anode offgas flowing out from the mixer is introduced into the combustion heater to burn the fuel in the anode offgas, and the coolant is heated by the heat energy generated thereby. Then, the heated coolant is supplied to the fuel cell via the warm-up coolant line to promote the warm-up of the fuel cell.

JP 2005-310464 A

  In the case where the turbine is driven by the combustion gas generated by the combustor, it is required to operate the combustor optimally from the viewpoint of power recovery by the turbine in order to operate the turbine efficiently. Specifically, the inflow of moisture into the combustor is avoided, and the fuel and the oxidant are introduced into the combustor in a sufficiently mixed state. If moisture flows into the combustor, moisture adheres to the catalyst held in the combustor to promote combustion, the ignitability of the fuel deteriorates, and the fuel and oxidant are not sufficiently mixed This is because unevenness in the distribution of the combustion temperature may cause the catalyst to deteriorate locally, or to reduce the combustion temperature in order to suppress the deterioration of the catalyst.

  The system described in Patent Document 1 does not include a turbine that drives a compressor, and the combustor provided on the downstream side of the mixer is for the purpose of acquiring thermal energy during warm-up. It is not intended to generate itself. For this purpose, in Patent Document 1, neither the cathode offgas nor the anode offgas is supplied to the combustor after the warm-up is completed, and bypasses the combustor for the treatment of exhaust hydrogen. It has been introduced into the dilution device. Therefore, the technique described in Patent Document 1 does not contribute to realizing an optimum operation of the combustor in a system in which the turbine is driven by the combustion gas generated by the combustor.

  In the present invention, a turbine that drives a compressor is connected to the cathode gas discharge passage of the combustion cell, and a combustor that generates combustion gas for driving the turbine is interposed in the cathode gas discharge passage. A gas-liquid separator is installed on the upstream side of the combustor in the cathode gas discharge passage, and fuel to be burned by the combustor is supplied on the upstream side of the gas-liquid separator in the cathode gas discharge passage. .

  According to the present invention, the inflow of moisture into the combustor can be suppressed, and the fuel and the cathode offgas can be introduced into the combustor in a sufficiently mixed state, so that the combustor can be operated more accurately. It becomes.

FIG. 1 is an overall configuration diagram schematically showing the configuration of a fuel cell system according to a first embodiment of the present invention. FIG. 2 is an overall configuration diagram schematically showing the configuration of the fuel cell system according to the second embodiment of the present invention. FIG. 3 is an overall configuration diagram schematically showing a configuration of a modification of the fuel cell system according to the embodiment. FIG. 4 is an overall configuration diagram schematically showing the configuration of the fuel cell system according to the third embodiment of the present invention. FIG. 5 is an overall configuration diagram schematically showing a configuration of a modification of the fuel cell system according to the embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 schematically shows the configuration of a fuel cell system 101 according to the first embodiment of the present invention.

  The fuel cell system 101 includes a fuel cell 10, a cathode gas supply / discharge mechanism 12, an anode gas supply / discharge mechanism 14, a heating / cooling mechanism 16, and a load device 18. The fuel cell system 101 further includes an electric compressor 20 and a turbine 22 in the cathode gas supply / exhaust mechanism 12. The electric compressor 20 includes a compressor 201 and an electric motor 202, and the turbine 22 is configured to be able to drive the compressor 201 independently of the electric motor 202. Although not clearly shown in FIG. 1, the fuel cell system 101 includes a system controller configured as an electronic control unit, and the operation state of the fuel cell system 101 such as the generated power of the fuel cell 10 is controlled by the system controller. In this embodiment, the fuel cell system 101 is mounted on a vehicle, and the fuel cell 10 generates electric power necessary for traveling of the vehicle.

  The fuel cell 10 is configured by stacking a plurality of fuel cells, and receives supply of air through the cathode gas supply / discharge mechanism 12 and supply of hydrogen gas through the anode gas supply / discharge mechanism 14. Electricity is generated by the chemical reaction between oxygen and hydrogen. In this embodiment, hydrogen is the fuel and oxygen in the air is the oxidant. The electricity generated by the power generation is used for driving an electric motor for driving the vehicle, and for driving various auxiliary machines such as the electric motor 202 provided in the electric compressor 20. In the present embodiment, the load device 18 is an electric motor for traveling the vehicle.

(Cathode gas supply / discharge mechanism)
The cathode gas supply / discharge mechanism 12 includes a cathode gas supply passage 121 and a cathode gas discharge passage 122.

  The cathode gas supply passage 121 is a passage through which air (cathode gas) supplied to the cathode electrode of the fuel cell 10 flows. One end of the cathode gas supply passage 121 is connected to the gas outlet of the compressor 201 and the other end is the fuel cell. It is connected to the gas inlet of 10 cathode electrodes. Air taken in from the atmosphere is pressurized by the compressor 201 and supplied to the cathode electrode of the fuel cell 10 via the cathode gas supply passage 121.

  The cathode gas discharge passage 122 is a passage through which the cathode off gas discharged from the cathode electrode of the fuel cell 10 flows, and is connected between the gas outlet of the cathode electrode of the fuel cell 10 and the gas inlet of the turbine 22. ing. In the cathode gas discharge passage 122, a gas-liquid separator 32, a hydrogen combustor 34, and a variable nozzle vane 36 are interposed in order from the upstream side with respect to the cathode off-gas flow. Cathode off-gas containing oxygen remaining without contributing to the power generation reaction in the fuel cell 10 and moisture generated by the power generation reaction is introduced into the gas-liquid separator 32, and the moisture is removed by the gas-liquid separator 32. After that, the gas passes through the hydrogen combustor 34 and is supplied to the turbine 22 under the control of the variable nozzle vane 36. The cathode off-gas is discharged to the outside through the turbine exhaust passage 123 after a part of the energy is used for driving the turbine 22.

  The gas-liquid separator 32 is a centrifugal gas-liquid separator, receives a cathode offgas containing moisture, and removes moisture from the cathode offgas. The gas-liquid separator 32 further removes moisture contained in the anode off-gas in addition to the cathode off-gas when the anode off-gas is introduced into the cathode gas discharge passage 122 as described later. The removed moisture is discharged to the outside through the drain nozzle.

  The hydrogen combustor 34 is a catalytic combustor that supports a catalyst such as platinum, and burns fuel and oxygen (oxidant) in the cathode off-gas on the catalyst to generate combustion gas. In this embodiment, the fuel is hydrogen in the anode offgas. A cathode off gas is supplied to the hydrogen combustor 34 through the cathode gas discharge passage 122, and an anode off gas is supplied from an anode gas circulation passage 143 to be described later through the anode off gas passage 144. Although not clearly shown in FIG. 1, a mixer may be incorporated in the hydrogen combustor 34 to promote mixing of the anode off-gas and the cathode off-gas before introduction into the catalyst.

  In the present embodiment, a catalytic combustion type combustor is adopted as the hydrogen combustor 34. However, the hydrogen combustor 34 is a combustor other than the catalytic combustor, such as a diffusion combustion type or a lean premixed combustion type combustor. It can also be adopted. According to the catalytic combustor, the generation of nitrogen compounds can be suppressed as compared with the case of other types of combustors such as a diffusion combustion type.

  The variable nozzle vane 36 is installed at the gas inlet of the turbine 22, and the opening degree of the nozzle vane (hereinafter referred to as “nozzle opening degree”) is variable. By changing the nozzle opening degree of the variable nozzle vane 36, the flow rate of the combustion gas supplied to the turbine 22 can be adjusted, and the power (recovered power) generated by the turbine 22 can be changed. The variable nozzle vane 36 increases the effective sectional area of the inlet passage to the turbine 22 in the open state, and relatively reduces the pressure loss of the combustion gas flowing into the turbine 22 from the cathode gas discharge passage 122. On the other hand, in the closed state, the effective cross-sectional area of the inlet channel to the turbine 22 is decreased, and the pressure loss of the combustion gas is relatively increased. Thus, by reducing the nozzle opening of the variable nozzle vane 36, it is possible to increase the recovery power by the turbine 22 and increase the operating pressure of the system.

  Further, a turbine bypass passage 124 is connected to the cathode gas discharge passage 122 on the downstream side of the hydrogen combustor 34 (in this embodiment, on the upstream side of the variable nozzle vane 36). Combustion gases other than those supplied to the turbine 22 among the combustion gases generated by the hydrogen combustor 34 are supplied to the heating / cooling mechanism 16 via the turbine bypass passage 124.

  Here, when the fuel cell 10 is in a low temperature state, it is possible to heat the fuel cell 10 using the heat of the combustion gas and promote warm-up. In the present embodiment, the heating / cooling mechanism 16 includes a heat exchanger 41, and combustion gas is supplied to the heat exchanger 41 via the turbine bypass passage 124, and the heat exchanger 41 cools the cooling water of the fuel cell 10. Is heated to promote warm-up of the fuel cell 10. After the heat is recovered by the heat exchanger 41, the combustion gas supplied to the heating / cooling mechanism 16 merges with the combustion gas flowing through the turbine exhaust passage 123 and is discharged to the outside.

(Electric compressor and turbine)
The electric compressor 20 includes a compressor 201 and an electric motor 202, and is configured such that a motor torque can be applied to the rotating shaft 203 of the compressor 201 by the electric motor 202. The compressor 201 is installed at the inlet of the cathode gas supply passage 121, and the air taken in from the atmosphere is compressed by the compressor 201 and supplied to the cathode electrode of the fuel cell 10 through the cathode gas supply passage 121. .

  The turbine 22 is installed between the cathode gas discharge passage 122 and the turbine exhaust passage 123 and operates by receiving supply of combustion gas from the hydrogen combustor 34. In the present embodiment, the impeller of the compressor 201 and the turbine blade of the turbine 22 are connected to each other via a rotating shaft 203, and the power recovered from the combustion gas by the turbine 22 is transmitted to the compressor 201 via the rotating shaft 203. Then, the compressor 201 is operated. The turbine 22 and the electric motor 202 can drive the compressor 201 independently of each other.

  Here, when the power demand of the compressor 201 is relatively large, the flow rate of the combustion gas flowing into the turbine 22 (turbine inlet flow rate), the temperature (turbine inlet temperature), and the pressure (turbine inlet pressure) are increased. It is possible to increase the recovery power by 22 and supply power to the compressor 201 as required. Specifically, by controlling the combustion state in the hydrogen combustor 34 and adjusting the nozzle opening of the variable nozzle vane 36, the combustion temperature (turbine inlet temperature) is increased or the nozzle is increased with respect to the increase in required power. By reducing the opening, it is possible to increase the recovery power by the turbine 22.

  The electric motor 202 is provided with a stator on the inner peripheral surface of the housing, and a rotor is formed coaxially with the rotating shaft 203. The electric motor 202 receives electric power from the fuel cell 10 and a battery (not shown) and applies motor torque to the rotating shaft 203. The power is applied (power running mode) to assist the rotational drive of the compressor 201 by the turbine 22. Furthermore, the electric motor 202 can generate electric power by the rotational power of the rotating shaft 203 (regeneration mode), and supplies the generated electric power to a battery (not shown).

(Anode gas supply / discharge mechanism)
The anode gas supply / discharge mechanism 14 includes a high-pressure hydrogen tank 141, an anode gas supply passage 142, an anode gas circulation passage 143, and an anode off-gas passage 144. In the present embodiment, a hydrogen heater 42 is interposed in the anode gas supply passage 142, and hydrogen gas heated by the hydrogen heater 42 can be supplied to the anode electrode of the fuel cell 10.

  The high-pressure hydrogen tank 141 is a gas storage container that stores the hydrogen gas supplied to the anode electrode of the fuel cell 10 while maintaining the high-pressure state.

  The anode gas supply passage 142 is a passage through which hydrogen gas (anode gas) supplied to the anode electrode of the fuel cell 10 flows, and is between the high-pressure hydrogen tank 141 and the gas inlet of the anode electrode of the fuel cell 10. It is connected. Hydrogen gas stored in the high-pressure hydrogen tank 141 is supplied to the anode electrode of the fuel cell 10 through the anode gas supply passage 142. In the present embodiment, the anode gas supply passage 142 is provided with a pressure control valve 51 on the downstream side of the hydrogen heater 42, and the pressure of the hydrogen gas supplied to the anode electrode of the fuel cell 10 by the pressure control valve 51 ( Flow rate) is adjusted. In the present embodiment, an ejector 52 is further provided on the downstream side of the pressure control valve 51, and hydrogen gas restricted by the pressure control valve 51 is supplied to the anode electrode of the fuel cell 10 through the ejector 52.

  The anode gas circulation passage 143 is a passage for circulating the anode off-gas discharged from the anode electrode of the fuel cell 10 to the anode electrode, the gas outlet of the anode electrode of the fuel cell 10, the anode gas supply passage 142, Connected between. In the present embodiment, the anode gas supply passage 142 is provided with an ejector 52 at the connection portion with the anode gas circulation passage 143, hydrogen remaining without contributing to the power generation reaction, moisture leaked from the cathode electrode, nitrogen, etc. The anode off gas containing the impurities is sucked into the anode gas supply passage 142 under the action of a negative pressure formed by the jet of hydrogen gas supplied from the high-pressure hydrogen tank 141 inside the ejector 52, and the fuel cell. 10 anode electrodes are supplied.

  The anode off-gas passage 144 is a passage through which a gas other than the one circulated to the anode gas supply passage 142 out of the anode off-gas discharged from the anode electrode of the fuel cell 10 flows, and the anode gas circulation passage 143 and the cathode gas discharge passage. 122. In the present embodiment, the anode off-gas passage 144 is connected to the upstream side of the gas-liquid separator 32 with respect to the cathode gas discharge passage 122, and the anode off-gas discharged from the anode electrode of the fuel cell 10 is the anode gas circulation passage 143. To the anode off-gas passage 144 and is introduced into the cathode gas discharge passage 122 on the upstream side of the gas-liquid separator 32 via the anode off-gas passage 144. As described above, in the present embodiment, the fuel introduction port 122a is formed at the connection portion between the anode off-gas passage 144 and the cathode gas discharge passage 122, and the anode off-gas passage 144, together with the flow rate adjusting valve 53 described later, A “fuel supply unit” that supplies fuel (hydrogen) to be burned by the hydrogen combustor 34 to 122 is configured. The “fuel inlet” refers to an opening of the cathode gas discharge passage 122 through which fuel or anode off gas flows when flowing into the cathode gas discharge passage 122. In this embodiment, the “fuel introduction port” is located upstream of the gas-liquid separator 32. It is formed. The anode off-gas that has been introduced into the cathode gas discharge passage 122 through the fuel introduction port 122a and merged with the cathode off-gas flowing through the cathode gas discharge passage 122 is removed from the gas-liquid separator 32, and then supplied to the hydrogen combustor 34. Supplied. A flow rate adjusting valve 53 is interposed in the anode off gas passage 144, and the flow rate of the anode off gas supplied to the hydrogen combustor 34 through the anode off gas passage 144 is adjusted by the flow rate adjusting valve 53.

(Heating / cooling mechanism)
The heating / cooling mechanism 16 includes a cooling water circulation passage 161, a cooling water branch passage 162, a heat exchanger 41, a hydrogen heater 42, a cooling water circulation pump 43, and a cooling device (not shown) such as a radiator.

  The cooling water circulation passage 161 is a passage for circulating the cooling water of the fuel cell 10 through the heat exchanger 41, and is connected between the cooling water inlet 10a and the cooling water outlet 10b of the fuel cell 10. . The cooling water flowing out from the cooling water outlet 10b of the fuel cell 10 flows into the heat exchanger 41 and is heated by the heat exchanger 41, and then from the cooling water inlet 10a of the fuel cell 10 to the cooling water passage of the fuel cell 10. Supplied. The cooling water supplied to the fuel cell 10 contributes to warm-up of the fuel cell 10 and is then discharged from the cooling water outlet 10b.

  The cooling water branch passage 162 is a passage through which cooling water used for heating the hydrogen gas supplied to the anode electrode of the fuel cell 10 flows. The cooling water branch passage 162 is arranged in parallel to the heat exchanger 41 and is connected to the cooling water circulation passage 161. Of these, the heat exchanger 41 is connected so as to straddle the upstream side and the downstream side. A part of the cooling water that has flowed out of the fuel cell 10 via the cooling water outlet 10 b flows into the cooling water branch passage 162 from the cooling water circulation passage 161 and is supplied to the hydrogen heater 42 via the cooling water branch passage 162. . Then, the cooling water supplied to the hydrogen heater 42 is used for heating the hydrogen gas, and then merges with the cooling water flowing through the cooling water circulation passage 161 on the downstream side of the heat exchanger 41, and the cooling water passage of the fuel cell 10. To be supplied.

  The heat exchanger 41 heats the cooling water by exchanging heat between the cooling water flowing through the cooling water circulation passage 161 and the combustion gas flowing through the turbine bypass passage 124. In the present embodiment, the heating / cooling mechanism 16 is provided with a cooling device (not shown), and the cooling water heated by heat exchange with the combustion gas can be cooled by this cooling device.

  The hydrogen heater 42 is configured as a heat exchanger, and heats the hydrogen gas supplied from the high-pressure hydrogen tank 141 by the heat recovered by the heating / cooling mechanism 16. Specifically, the cooling water heated by the heat exchanger 41 of the heating / cooling mechanism 16 and the hydrogen gas stored in the high-pressure hydrogen tank 141 are supplied to the hydrogen heater 42, and between them, Hydrogen gas is heated by heat exchange.

(Load device)
The load device 18 is connected between the positive electrode terminal and the negative electrode terminal of the fuel cell 10, and is driven by the supply of electric power supplied from the fuel cell 10 or a battery (not shown). In the present embodiment, the load device 18 is an electric motor for traveling the vehicle.

(Explanation of effects)
The fuel cell system 101 according to the present embodiment is configured as described above, and the effects obtained by the present embodiment will be summarized below.

  First, in the present embodiment, an anode off gas passage 144 is extended from the anode gas circulation passage 143, and the anode off gas passage 144 and the cathode gas discharge passage 122 are connected to each other with respect to the cathode off gas flow in the cathode gas discharge passage 122. The “fuel supply unit” is configured by the anode off-gas passage 144 and the flow rate adjustment valve 53 connected upstream of the separator 32. As a result, the anode off gas (specifically, hydrogen in the anode off gas) is supplied to the hydrogen combustor 34 via the fuel inlet 122a formed on the upstream side of the gas-liquid separator 32, and the anode off gas. And the cathode offgas (specifically, oxygen in the cathode offgas) are sufficiently mixed through the gas-liquid separator 32 and water contained in the anode offgas and the cathode offgas is removed. 34 can be supplied.

  Therefore, according to the present embodiment, inflow of moisture to the hydrogen combustor 34 is avoided, deterioration of ignitability due to adhesion of moisture to the catalyst is suppressed, and fuel and oxidant are added to the hydrogen combustor 34. Introduced in a sufficiently mixed state, the combustion temperature distribution is made close to uniformity, deterioration due to local heating of the catalyst is prevented, and the hydrogen combustor 34 is used until reaching a higher temperature operating region. Is possible.

  Furthermore, since the gas-liquid separator 32 is interposed between the fuel inlet 122a of the fuel supply unit and the hydrogen combustor 34, it is easy to ensure the distance required for mixing the fuel and the oxidant.

  In this embodiment, hydrogen in the anode off gas is the fuel, and oxygen in the cathode off gas is the oxidant.

  Secondly, in the present embodiment, the anode off gas is introduced into the cathode gas discharge passage 122, and hydrogen in the anode off gas is used to generate the combustion gas. Thereby, useless discharge | release of hydrogen can be suppressed and the operating efficiency of the fuel cell system 101 can be improved as the whole system.

  In addition to the above, in the present embodiment, a catalytic combustor is adopted as the hydrogen combustor 34, and the inflow of water into the hydrogen combustor 34 can be avoided, thereby preventing the adhesion of moisture to the catalyst and igniting the fuel. It is possible to prevent the sex from deteriorating.

  Further, a centrifugal type is adopted as the gas-liquid separator 32, and the anode off-gas is introduced upstream of the gas-liquid separator 32, so that the gas flowing into the gas-liquid separator 32 (cathode off-gas and anode off-gas The flow rate of the mixed gas) can be increased, and the function of centrifugation can be more effectively generated.

  In the present embodiment, the anode off-gas passage 144 is connected to the cathode gas discharge passage 122 on the upstream side of the gas-liquid separator 32, and the fuel inlet upstream of the gas-liquid separator 32 is connected to the hydrogen combustor 34. The anode off gas is supplied via 122a, but instead of or in addition to the anode off gas, the hydrogen gas supplied from the high-pressure hydrogen tank 141 is directly supplied to the cathode gas discharge passage 122 (in other words, It may also be introduced (without going through the fuel cell 10). Thereby, the hydrogen gas and the cathode off gas can be supplied to the hydrogen combustor 34 through the gas-liquid separator 32 in a sufficiently mixed state.

(Second Embodiment)
FIG. 2 schematically shows the configuration of a fuel cell system 102A according to the second embodiment of the present invention.

  In this embodiment, as in the first embodiment, the anode offgas passage 144 is connected to the cathode gas discharge passage 122, the anode offgas flowing through the anode gas circulation passage 143 is branched to the anode offgas passage 144, and the anode offgas passage 144 is connected. Through the cathode gas discharge passage 122. The anode off-gas flowing into the cathode gas discharge passage 122 is introduced into the gas-liquid separator 32 together with the cathode off-gas flowing through the cathode gas discharge passage 122, and after the moisture is removed by the gas-liquid separator 32, the anode off-gas is supplied to the hydrogen combustor 34. Is done.

  In the present embodiment, the cathode gas supply passage 121 and the cathode gas discharge passage 122 are connected to each other via a bypass passage 125. Part of the air compressed by the compressor 201 is supplied to the cathode electrode of the fuel cell 10, and the remaining part flows into the bypass passage 125 from the cathode gas supply passage 121, bypasses the fuel cell 10, and cathode gas. It is introduced into the discharge passage 122. The air that has flowed into the cathode gas discharge passage 122 merges with the cathode off-gas discharged from the cathode electrode of the fuel cell 10, flows into the gas-liquid separator 32, and is supplied to the hydrogen combustor 34.

  A bypass valve 38 is provided in the bypass passage 125. The bypass valve 38 adjusts the flow rate of the air flowing through the bypass passage 125. Specifically, when the flow rate of air discharged by the compressor 201 exceeds the flow rate of air required for power generation by the fuel cell 10, the opening degree of the bypass valve 38 is increased and the cathode electrode of the fuel cell 10 is increased. By reducing the flow rate of the air supplied to the fuel cell 10, the electrolyte membrane of the fuel cell 10 is prevented from being excessively dried.

  As described above, when the cathode gas supply / discharge mechanism 12 includes the bypass passage 125, the anode off-gas passage 144 and the cathode gas discharge passage 122 are connected upstream of the gas-liquid separator 32, and the gas-liquid separator 32. A fuel introduction port 122a is formed on the upstream side of the gas, and the anode off-gas is supplied to the hydrogen combustor 34 via the fuel introduction port 122a on the upstream side of the gas-liquid separator 32. Similarly, the anode off-gas and the cathode off-gas can be sufficiently mixed through the gas-liquid separator 32 and supplied to the hydrogen combustor 34 in a state where moisture contained in the anode off-gas and the cathode off-gas is removed. . And since the gas-liquid separator 32 is interposed between the fuel inlet 122a of the fuel supply unit and the hydrogen combustor 34, it becomes easy to secure a distance required for mixing the fuel and the oxidant.

  In the present embodiment, a bypass passage 125 that bypasses the fuel cell 10 is formed, and air is introduced from the cathode gas supply passage 121 to the cathode gas discharge passage 122 via the bypass passage 125, and thus supplied to the hydrogen combustor 34. It is possible to relatively reduce the amount occupied by the cathode off-gas in the mixed gas, and more reliably avoid the inflow of moisture into the hydrogen combustor 34. Further, when the air required for power generation of the fuel cell 10 is small and the flow rate of the cathode off gas is insufficient with respect to the amount required for combustion in the hydrogen combustor 34, the bypass passage 125 is used regardless of the operating state of the fuel cell 10. It is possible to introduce air into the cathode gas discharge passage 122 via the air to compensate for the shortage of the cathode off gas with air.

  The connecting portion between the anode off gas passage 144 and the cathode gas discharge passage 122 (the fuel introduction port 122a is formed at this connecting portion) is bypassed with respect to the flow of the cathode off gas flowing through the cathode gas discharge passage 122 as shown in FIG. It may be downstream (point P2) from the connection portion P1 between the passage 125 and the cathode gas discharge passage 122, or may be upstream (point P3). By connecting the anode off-gas passage 144 and the cathode gas discharge passage 122 to the upstream side (point P3) from the connection portion P1, the distance from the fuel inlet 122a to the hydrogen combustor 34 is extended. And further mixing with an oxidizing agent can be further promoted. On the other hand, when the connecting portion P2 on the downstream side of the connecting portion P1 is adopted, the fuel inlet 122a is closer to the hydrogen combustor 34 than when the connecting portion P3 on the upstream side is adopted. The responsiveness of the combustor 34 can be improved.

  In this embodiment, hydrogen in the anode off gas is a fuel, and oxygen in the cathode off gas and air is an oxidant. The anode off gas passage 144 and the flow rate adjusting valve 53 constitute a “fuel supply unit”.

  In the present embodiment, the anode off gas is supplied to the hydrogen combustor 34 via the fuel inlet 122a upstream of the gas-liquid separator 32. However, instead of or in addition to the anode off gas, a high pressure The hydrogen gas supplied from the hydrogen tank 141 may be directly introduced into the cathode gas discharge passage 122. Thereby, the hydrogen gas and the cathode off gas can be supplied to the hydrogen combustor 34 through the gas-liquid separator 32 in a sufficiently mixed state.

(Modification of the second embodiment)
FIG. 3 is an overall configuration diagram schematically showing a configuration of a modified embodiment 102B of the fuel cell system according to the second embodiment.

  When the difference from the fuel cell system 102A shown in FIG. 2 is described, the anode gas supply passage 142 and the cathode gas discharge passage 122 are connected via the hydrogen gas passage 145, and the flow rate adjustment valve 54 is connected to the hydrogen gas passage 145. It is disguised. Specifically, the anode gas supply passage 142 is downstream of the hydrogen heater 42 with respect to the hydrogen gas flow (in this embodiment, upstream of the pressure control valve 51), and the cathode gas discharge passage 122 is cathode off-gas. An upstream side of the hydrogen combustor 34 with respect to the flow (in this embodiment, a downstream side of the gas-liquid separator 32) is connected via a hydrogen gas passage 145. A second fuel introduction port 122b is formed at a connection portion between the hydrogen gas passage 145 and the cathode gas discharge passage 122, and the hydrogen gas passage 145 and the flow rate control valve 54 constitute a “second fuel supply portion”. The “second fuel inlet” refers to an opening of the cathode gas discharge passage 122 through which fuel (hydrogen) passes when flowing into the cathode gas discharge passage 122 on the downstream side of the gas-liquid separator 32. Part of the hydrogen gas that has flowed out of the high-pressure hydrogen tank 141 and passed through the hydrogen heater 42 flows into the hydrogen gas passage 145 from the anode gas supply passage 142 and is upstream of the hydrogen combustor 34 via the hydrogen gas passage 145. Is introduced into the cathode gas discharge passage 122 and supplied to the hydrogen combustor 34. The flow rate of the hydrogen gas supplied to the hydrogen combustor 34 via the hydrogen gas passage 145 is adjusted by the flow rate adjustment valve 54 interposed in the hydrogen gas passage 145.

  The configuration other than the above is the same as that of the fuel cell system 102A shown in FIG.

  In this way, in addition to the anode off-gas, hydrogen gas supplied from the high-pressure hydrogen tank 141 can be directly introduced into the hydrogen combustor 34 via the hydrogen gas passage 145 (in other words, not via the fuel cell 10). As a result, when the amount of hydrogen gas required for power generation of the fuel cell 10 is small and the flow rate of the anode off gas is insufficient with respect to the amount required for combustion in the hydrogen combustor 34, regardless of the operating state of the fuel cell 10. Hydrogen gas is introduced into the cathode gas discharge passage 122 via the hydrogen gas passage 145, and the shortage of anode off gas is compensated with hydrogen gas, so that an optimal amount of fuel can be supplied to the hydrogen combustor 34. .

  Furthermore, since the fuel inlet (second fuel inlet 122b) of the second fuel supply unit is formed between the gas-liquid separator 32 and the hydrogen combustor 34, it is closer to the hydrogen combustor 34. The hydrogen gas can be introduced into the cathode gas discharge passage 122 at the position, and the hydrogen combustor 34 can be operated with higher responsiveness. The hydrogen gas can be supplied to the hydrogen combustor 34 in a dry state without flowing into the gas-liquid separator 32, so that the ignitability of the fuel can be maintained better and the hydrogen gas can be separated into the gas-liquid separator. The leakage of hydrogen gas from the drain nozzle or the like accompanying the flow into the vessel 32 can be avoided.

  In this embodiment, hydrogen in the anode off gas and hydrogen supplied as hydrogen gas from the high-pressure hydrogen tank 141 are fuel, and the cathode off gas and oxygen in the air are oxidants. The anode off-gas passage 144 and the flow rate adjustment valve 53 constitute a “first fuel supply unit”, and the hydrogen gas passage 145 and the flow rate adjustment valve 54 constitute a “second fuel supply unit”. The hydrogen gas passage 145 corresponds to a “fuel passage”.

(Third embodiment)
FIG. 4 schematically shows the configuration of a fuel cell system 103A according to the third embodiment of the present invention.

  In the above description, the case where the anode off gas branched from the anode gas circulation passage 143 is directly introduced from the anode off gas passage 144 to the cathode gas discharge passage 122 has been described. On the other hand, in the present embodiment, a bypass passage 125 that bypasses the fuel cell 10 is formed between the cathode gas supply passage 121 and the cathode gas discharge passage 122, and the anode offgas passage 144 is connected to the bypass passage 125. The anode off gas branched from the anode gas circulation passage 143 is indirectly introduced into the cathode gas discharge passage 122 through the bypass passage 125.

  In the present embodiment, the cathode gas supply passage 121 and the cathode gas discharge passage 122 are connected to each other via a bypass passage 125, and a part of the air compressed by the compressor 201 is transferred from the cathode gas supply passage 121 to the bypass passage 125. Is introduced into the cathode gas discharge passage 122. The air that has flowed into the cathode gas discharge passage 122 merges with the cathode off gas flowing through the cathode gas discharge passage 122 on the upstream side of the gas-liquid separator 32 and is supplied to the hydrogen combustor 34. A bypass valve 38 is provided in the bypass passage 125, and by reducing the flow rate of air supplied to the cathode electrode of the fuel cell 10 by the bypass valve 38, it is possible to prevent the electrolyte membrane of the fuel cell 10 from being dried excessively. It is the same as in the second embodiment.

  In the present embodiment, the anode off-gas passage 144 is connected between the anode gas circulation passage 143 and the downstream side of the flow rate adjustment valve 38 with respect to the air flow in the bypass passage 125. Thereby, in this embodiment, the fuel introduction port 122a is formed on the upstream side of the gas-liquid separator 32 as a communication port between the bypass passage 125 and the cathode gas discharge passage 122, and the gas-liquid separation is performed with respect to the hydrogen combustor 34. The anode off gas is supplied through the fuel inlet 122 a upstream of the vessel 32.

  Therefore, according to the present embodiment, moisture contained in the anode off-gas and the cathode off-gas is removed by the gas-liquid separator 32 before being supplied to the hydrogen combustor 34, and prior to the supply to the hydrogen combustor 34. The anode off gas and the cathode off gas can be sufficiently mixed. Here, in the present embodiment, the anode offgas passage 144 is connected to the bypass passage 125, and the anode offgas is caused to flow into the cathode gas discharge passage 122 through the bypass passage 125 and supplied to the hydrogen combustor 34. 125 can be used for the diffusion of the fuel, and the mixing of the fuel and the oxidant can be further promoted.

  Furthermore, in the present embodiment, the anode off gas passage 144 is connected to the bypass passage 125, so that the communication port of the anode off gas passage 144 can be prevented from being blocked by freezing of moisture in the cathode off gas.

  Further, a bypass passage 125 that bypasses the fuel cell 10 is formed, and air can be introduced into the cathode gas discharge passage 122 from the cathode gas supply passage 121 through the bypass passage 125, so that the fuel is supplied to the hydrogen combustor 34. It is possible to relatively reduce the amount of the mixed gas occupied by the cathode off-gas and more reliably avoid the inflow of moisture into the hydrogen combustor 34. When the flow rate of the cathode off gas is insufficient with respect to the amount necessary for combustion in the hydrogen combustor 34, air is introduced into the cathode gas discharge passage 122 via the bypass passage 125 regardless of the operating state of the fuel cell 10. In addition, the shortage of cathode offgas can be compensated with air.

  In this embodiment, hydrogen in the anode off gas is a fuel, and oxygen in the cathode off gas and air is an oxidant. The anode off gas passage 144, the bypass passage 125, and the flow rate adjusting valves 38 and 53 constitute a “fuel supply unit”.

(Modification of the third embodiment)
FIG. 5 schematically shows a configuration of a modified aspect of the fuel cell system 103B according to the third embodiment.

  When the difference from the fuel cell system 103A shown in FIG. 4 is described, the anode gas supply passage 142 and the cathode gas discharge passage 122 are connected via the hydrogen gas passage 145, and the flow rate adjustment valve 54 is connected to the hydrogen gas passage 145. It is disguised. A second fuel introduction port 122b is formed at a connection portion between the hydrogen gas passage 145 and the cathode gas discharge passage 122, and the hydrogen gas passage 145 and the flow rate control valve 54 constitute a “second fuel supply portion”. Part of the hydrogen gas that has flowed out of the high-pressure hydrogen tank 141 and passed through the hydrogen heater 42 is upstream from the hydrogen combustor 34 via the hydrogen gas passage 145 from the anode gas supply passage 142 (in this embodiment, gas-liquid The gas is introduced into the cathode gas discharge passage 122 on the downstream side of the separator 32 and supplied to the hydrogen combustor 34. The flow rate of the hydrogen gas supplied to the hydrogen combustor 34 via the hydrogen gas passage 145 is adjusted by the flow rate adjustment valve 54 interposed in the hydrogen gas passage 145.

  The configuration other than the above is the same as that of the fuel cell system 103A shown in FIG.

  As described above, the hydrogen gas supplied from the high-pressure hydrogen tank 141 in addition to the anode off-gas can be directly introduced into the hydrogen combustor 34 through the hydrogen gas passage 145, and thus the modification of the second embodiment can be achieved. Similarly, when the flow rate of the anode off gas is insufficient with respect to the amount necessary for combustion in the hydrogen combustor 34, hydrogen is supplied to the cathode gas discharge passage 122 via the hydrogen gas passage 145 regardless of the operating state of the fuel cell 10. Gas can be introduced to compensate for the shortage of anode off gas with hydrogen gas.

  Furthermore, since the fuel inlet (second fuel inlet 122b) of the second fuel supply unit is formed between the gas-liquid separator 32 and the hydrogen combustor 34, it is closer to the hydrogen combustor 34. The hydrogen gas can be introduced into the cathode gas discharge passage 122 at the position, and the hydrogen combustor 34 can be operated with higher responsiveness. Then, by allowing hydrogen gas to be supplied to the hydrogen combustor 34 in a dry state, the ignitability of the fuel can be maintained better.

  In this embodiment, hydrogen in the anode off gas and hydrogen supplied as hydrogen gas from the high-pressure hydrogen tank 141 are fuel, and the cathode off gas and oxygen in the air are oxidants. The anode off gas passage 144, the bypass passage 125, and the flow rate adjustment valves 38, 53 constitute a “first fuel supply unit”, and the hydrogen gas passage 145 and the flow rate adjustment valve 54 constitute a “second fuel supply unit”. The hydrogen gas passage 145 corresponds to a “fuel passage”.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various changes and modifications can be made within the scope of the matters described in the claims. Not too long.

101, 102A, 102B, 103A, 103B ... Fuel cell system 12 ... Cathode gas supply / discharge mechanism 14 ... Anode gas supply / discharge mechanism 16 ... Heating / cooling mechanism 18 ... Load device 20 ... Electric compressor 22 ... Turbine 32 ... Gas-liquid separator 34 ... Hydrogen combustor 38 ... Bypass valve 41 ... Heat exchanger 42 ... Hydrogen heater 51 ... Pressure regulating valve 52 ... Ejector 53 ... Flow rate regulating valve 54 ... Hydrogen gas passage 121 ... Cathode gas supply passage 122 ... Cathode gas discharge passage 122a ... Fuel inlet (first fuel inlet)
122b ... Fuel inlet (second fuel inlet)
DESCRIPTION OF SYMBOLS 125 ... Bypass passage 141 ... High pressure hydrogen tank 142 ... Anode gas supply passage 143 ... Anode gas circulation passage 144 ... Anode off gas passage 145 ... Hydrogen gas passage 201 ... Compressor 202 ... Electric motor 203 ... Rotating shaft P1 ... Bypass passage and cathode gas discharge Connection portion with passage P2, P3... Connection portion between anode off-gas passage and cathode gas discharge passage

Claims (8)

A fuel cell that generates electricity by receiving fuel and an oxidant; and
A compressor for supplying an oxidant to the cathode of the fuel cell;
A turbine connected to the cathode of the fuel cell via a cathode gas discharge passage and driving the compressor;
A combustor that is interposed in the cathode gas discharge passage and generates combustion gas for driving the turbine;
A gas-liquid separator disposed upstream of the combustor in the cathode gas discharge passage;
A fuel supply unit that supplies fuel to be burned in the combustor to the upstream side of the gas-liquid separator in the cathode gas discharge passage;
A fuel cell system comprising:   The fuel cell system according to claim 1, wherein the fuel supply unit supplies anode offgas of the fuel cell to the cathode gas discharge passage. The bypass passage disposed in parallel to the fuel cell and connecting the cathode gas supply passage of the fuel cell and the cathode gas discharge passage upstream of the gas-liquid separator. A fuel cell system,
The fuel supply unit has an anode off-gas passage that communicates with the anode electrode of the fuel cell and is connected to the bypass passage. By introducing the anode off-gas into the bypass passage, the anode is introduced into the cathode gas discharge passage. A fuel cell system that supplies off-gas. The fuel supply unit
A first fuel supply unit for supplying the anode off gas to the upstream side of the gas-liquid separator in the cathode gas discharge passage;
A second fuel supply section for supplying the fuel between the gas-liquid separator and the combustor in the cathode gas discharge passage;
The fuel cell system according to claim 2, comprising: A fuel tank for storing fuel supplied to the fuel cell;
An anode gas supply passage connecting the fuel tank and the anode electrode of the fuel cell;
The fuel cell system according to claim 4, further comprising:
The second fuel supply unit has a fuel passage having one end connected to the anode gas supply passage and the other end connected to the cathode gas discharge passage between the gas-liquid separator and the combustor. Battery system.   The fuel cell system according to any one of claims 1 to 5, wherein the combustor is a catalytic combustor including a catalyst that promotes combustion of the fuel and the oxidant.   The fuel cell system according to any one of claims 1 to 6, wherein the gas-liquid separator is a centrifugal gas-liquid separator. The oxidant is supplied to the cathode of the fuel cell through a compressor that can be driven by a turbine.
The fuel cell cathode off gas and fuel or the fuel cell anode off gas are mixed to produce a mixed gas,
Removing moisture from the mixed gas;
Introducing the mixed gas from which moisture has been removed into the combustor, and burning the fuel or fuel in the anode off-gas with an oxidant in the cathode off-gas to produce combustion gas;
A method of operating a fuel cell system, wherein the combustion gas is supplied to the turbine to drive the turbine.

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