초록 ▼

The present invention relates to a fuel cell system and a method of operating same, The fuel cell has a first reactant inlet, a first reactant outlet, a second reactant inlet, a second reactant outlet. The invention involves (a) providing a first reactant incoming stream to the first reactant inlet

The present invention relates to a fuel cell system and a method of operating same, The fuel cell has a first reactant inlet, a first reactant outlet, a second reactant inlet, a second reactant outlet. The invention involves (a) providing a first reactant incoming stream to the first reactant inlet; (b) providing a second reactant incoming stream to the second reactant inlet; (c) monitoring a fuel cell state variable indicative of flooding; (d) based on the fuel cell state variable, determining whether the fuel cell is flooded; and, (e) providing an additional amount of the first reactant to the fuel cell when the fuel cell is flooded.

대표청구항 ▼

The invention claimed is: 1. A fuel cell system, comprising: (a) a fuel cell having a cathode, a first reactant inlet and a first reactant outlet both connected to the cathode, and an anode, a second reactant inlet and a second reactant outlet both connected to the anode; (b) a first reactant suppl

The invention claimed is: 1. A fuel cell system, comprising: (a) a fuel cell having a cathode, a first reactant inlet and a first reactant outlet both connected to the cathode, and an anode, a second reactant inlet and a second reactant outlet both connected to the anode; (b) a first reactant supply subsystem including a first reactant supply means for supplying a first reactant incoming stream to the first reactant inlet of the fuel cell; (c) a second reactant supply subsystem for supplying a second reactant incoming stream to the second reactant inlet of the fuel cell; (d) a monitoring device for monitoring a fuel cell state variable indicative of flooding of the fuel cell; (e) a controller for controlling the first reactant supply means to provide an additional amount of the first reactant to the fuel cell cathode based on the fuel cell state variable, and for controlling the second reactant supply means to provide an additional amount of the second reactant to the fuel cell anode based on the fuel cell state variable, whereby flooding occurring in either one of the anode and cathode is displaced by the additional amounts of the first and second reactants; and (f) a second reactant recirculation line connected between the second reactant outlet and the second reactant inlet, and a second reactant purge means connected to the second reactant outlet, wherein the controller is operable to control the second reactant purge means to purge at least a portion of the second reactant exhaust stream from the second reactant outlet when the fuel cell state variable indicates the fuel cell is flooded. 2. A fuel cell system as claimed in claim 1, wherein the controller controls the first reactant supply means to operate at maximum capacity when the fuel cell state variable indicates the fuel cell is flooded. 3. A fuel cell system as claimed in claim 2, wherein the controller is operable to control the first reactant supply means to stop supplying the additional amount of the first reactant and to control the second reactant purge means to stop purging when the fuel cell state variable indicates the fuel cell is no longer flooded. 4. A fuel cell system as defined in claim 3 wherein the fuel cell state variable is a cell voltage and the monitoring device comprises a voltage monitor for monitoring the cell voltage. 5. A fuel cell system as defined in claim 4 wherein the controller is operable to determine that the fuel cell is flooded when the cell voltage is less than a first value. 6. A fuel cell system as defined in claim 5 wherein the controller is operable to determine the fuel cell is no longer flooded when the cell voltage is more than a second value. 7. A fuel cell system as claimed in claim 6, wherein the first value is same as the second value. 8. A method of operating a fuel cell system, the fuel cell having a cathode, a first reactant inlet and a first reactant outlet both connected to the cathode, and an anode, a second reactant inlet and a second reactant outlet both connected to the anode, said method comprising: (a) providing a first reactant incoming stream to the first reactant inlet for supply to the cathode; (b) providing a second reactant incoming stream to the second reactant inlet for supply to the anode; (c) monitoring a fuel cell state variable indicative of flooding; (d) based on the fuel cell state variable, determining whether the fuel cell is flooded; (e) providing for recirculation of at least part of the second reactant from the second reactant outlet to the second reactant inlet; (f) providing an additional amount of both of the first and second reactants to the fuel cell when the fuel cell is flooded, and for the second reactant, purging at least part of the second reactant from the second reactant outlet. 9. A method of operating a fuel cell system as claimed in claim 8, wherein step (e) further comprises increasing the rate at which the first reactant supplied to the fuel cell to the maximum capacity of the fuel cell system when the fuel cell state variable indicates the fuel cell is flooded. 10. A method of operating a fuel cell system as claimed in claim 9, further comprising stopping the additional amount of the first reactant being supplied to the fuel cell and the purging of the second reactant from the second reactant outlet, when the fuel cell state variable indicates the fuel cell is no longer flooded. 11. A method of operating a fuel cell as claimed in claim 9 wherein the fuel cell state variable is a cell voltage, and step (c) comprises measuring the cell voltage. 12. A method of operating a fuel cell system as claimed in claim 11 wherein step (d) comprises determining the fuel cell is flooded when the cell voltage is less than a first value. 13. A method as defined in claim 12 wherein step (d) comprises determining the fuel cell is no longer flooded when the cell voltage is more than a second value. 14. A method of operating a fuel cell system as claimed in claim 12, wherein the first value is same as the second value. 15. A fuel system as claimed in claim 4, wherein the fuel cell comprises a plurality of fuel cells and wherein the fuel cell state variable comprises the voltages, the individual fuel cells and the monitor monitors the individual fuel cell voltages. 16. A fuel cell system as claimed in claim 3, wherein the first reactant comprises an oxidant and the second reactant comprises a fuel, and wherein a first reactant recirculation line connects the first reactant outlet to the first reactant inlet, for recirculation of the first reactant, and wherein the first reactant recirculation line passes through a humidifier, for humidifying one of the first and second reactants. 17. A fuel cell system as claimed in claim 16, wherein the humidifier is incorporated in the second reactant supply subsystem for humidifying the second reactant, and wherein a regenerative dryer is provided for humidifying the first reactant, with the first reactant recirculation line passing through the regenerative dryer and with the regenerative dryer being located in the first reactant supply subsystem. 18. A fuel cell system as claimed in claim 17, wherein the first reactant recirculation line passes through the humidifier and then through the regenerative dryer. 19. A fuel cell system as claimed in claim 17, wherein the humidifier and the regenerative dryer are configured in the recirculation line in one of: (a) the humidification and the regenerative dryer being arranged in parallel; and (b) the humidifier and the regenerative dryer being located sequentially in the first reactant recirculation line, with a bypass line being provided around the upstream one of the humidifier and the regenerative dryer. 20. A fuel cell system as claimed in claim 16, wherein the first and second reactant outlets are connected to a common reactant discharge line. 21. A method of operating a fuel cell system as claimed in claim 11, the method being applied to a fuel cell having a plurality of individual fuel cells, and wherein step (c) comprises measuring the voltage of each individual fuel cell. 22. A method of operating a fuel cell system as claimed in claim 8, including providing the first reactant as an oxidant and the second reactant as a fuel, and recirculating the first reactant through a humidifier for humidifying at least one of the first and second reactants. 23. A method of operating a fuel cell system as claimed in claim 22, including recirculating the first reactant through a humidifier for humidifying the second reactant and through a regenerative dryer for humidifying the first reactant. 24. A method of operating a fuel cell system as claimed in claim 23, wherein the recirculated second reactant first passes through the humidifier for the second reactant and then through the regenerative dryer for humidifying the first reactant. 25. A method of operating a fuel cell system as claimed in claim 23, including passing one portion of the recirculated first reactant through the humidifier and another portion through the regerative dryer, for parallel humidification of the first and second reactants. 26. A method of operating a fuel cell system as claimed in claim 24, including providing a bypass line around the one of the humidifier and the regenerative dryer that is upstream, for optionally bypassing part of the recirculated first reactant. 27. A method of operating a fuel cell system as claimed in claim 22, including combining exhausted first and second reactants from the first and second reactant outlets and supplying the combined exhausted first and second reactants to a common discharge line.