초록 ▼

Systems and methods of controlling fuel cell electric power generation systems. In one embodiment, the control system comprises a current detector for measuring an output current of the fuel cell stack and generating a corresponding current signal, a flow detector for measuring a flow rate of a proc

Systems and methods of controlling fuel cell electric power generation systems. In one embodiment, the control system comprises a current detector for measuring an output current of the fuel cell stack and generating a corresponding current signal, a flow detector for measuring a flow rate of a process gas stream and generating a corresponding flow rate signal, a sensor for measuring a concentration of a component of the reformate stream and generating a corresponding concentration signal, and a processor. The processor is configured to maintain hydrogen utilization in the fuel cell stack at about a user selectable value or within a user selectable range by generating an output signal as a function of the current signal, the flow rate signal and the first concentration signal. The output signal is employed in controlling a process variable impacting hydrogen utilization.

대표청구항 ▼

1. A control system for a fuel cell electric power generation system having a fuel processing system comprising a reformer for converting a reactant stream comprising a hydrocarbon fuel to a reformate stream, and a fuel cell stack fluidly connected to the fuel processing system to receive the reform

1. A control system for a fuel cell electric power generation system having a fuel processing system comprising a reformer for converting a reactant stream comprising a hydrocarbon fuel to a reformate stream, and a fuel cell stack fluidly connected to the fuel processing system to receive the reformate stream, the control system comprising:a current detector for measuring an output current of the fuel cell stack and generating a corresponding current signal; a first flow detector for measuring a first flow rate of a process gas stream and generating a corresponding first flow rate signal; a first sensor for measuring a concentration of a first component of the reformate stream and generating a corresponding first concentration signal; and a processor configured to maintain hydrogen utilization in the fuel cell stack at about a user selectable value or within a user selectable range by generating an output signal as a function of the current signal, the flow rate signal and the first concentration signal, the output signal being for use in controlling a process variable impacting hydrogen utilization. 2. The control system of claim 1 wherein the controlled process variable is the output current of the fuel cell stack, the control system further comprising an output current regulator configured to control the output current in response to the output signal from the processor.3. The control system of claim 1 wherein the controlled process variable is the flow rate of the fuel stream into the reformer, the control system further comprising a flow controller and flow control element configured to control the flow rate of the fuel in response to the output signal from the processor.4. The control system of claim 1 wherein the processor is configured to maintain hydrogen utilization in the fuel cell stack within a user selected range, the user selected range being between about 75% and about 90%.5. The control system of claim 1 wherein the processor is configured to maintain hydrogen utilization in the fuel cell stack within a user selected range, the user selected range being between about 80% and about 85%.6. The control system of claim 1 wherein the processor is configured to maintain hydrogen utilization in the fuel cell stack at about a user selected value, the user selected value being about 80%.7. The control system of claim 1 wherein the first sensor measures a carbon monoxide concentration.8. The control system of claim 7, further comprising a second sensor for measuring a concentration of a second component of the reformate stream and generating a corresponding second concentration signal, wherein the output signal is also a function of the second concentration signal.9. The control system of claim 8 wherein the second sensor measures a carbon dioxide concentration.10. The control system of claim 1 wherein the fuel processing system further comprises a shift reactor fluidly connected to the reformer for receiving the reformate stream therefrom, wherein the first sensor is located downstream of the shift reactor.11. The control system of claim 10 wherein the fuel processing system further comprises a selective oxidizer fluidly connected to the shift reactor for receiving the reformate stream therefrom, wherein the first sensor is located downstream of the selective oxidizer.12. The control system of claim 10 wherein the first sensor measures a methane concentration.13. The control system of claim 10 wherein the first sensor measures a carbon dioxide concentration.14. The control system of claim 10 wherein the fuel processing system further comprises a condenser fluidly connected to the shift reactor for receiving the reformate stream therefrom, wherein the first sensor is located downstream of the condenser.15. The control system of claim 14, further comprising a temperature sensor for measuring a temperature of the reformate stream and generating a corresponding temperature signal, wherein the output signal is also a function of the temperature signal.16. The control system of claim 14, further comprising a pressure sensor for measuring a pressure of the reformate stream and generating a corresponding pressure signal, wherein the output signal is also a function of the pressure signal.17. The control system of claim 1 wherein the reactant stream further comprises a feed water stream.18. The control system of claim 17, further comprising a second flow detector for measuring a second flow rate of the feed water stream and generating a corresponding second flow rate signal, wherein the output signal is also a function of the second flow rate signal.19. The control system of claim 17, further comprising a monitor for determining a steam:carbon ratio of the reactant stream and generating a corresponding steam:carbon ratio signal, wherein the output signal is also a function of the steam:carbon ratio signal.20. The control system of claim 17 wherein the first sensor measures a water concentration.21. The control system of claim 1 wherein the reactant stream further comprises a gas stream comprising oxygen.22. The control system of claim 21, further comprising a second flow detector for measuring a second flow rate of the gas stream and generating a corresponding second flow rate signal, wherein the output signal is also a function of the second flow rate signal.23. The control system of claim 21, further comprising a monitor for determining an oxygen-containing gas:fuel ratio of the reactant stream and generating a corresponding gas:fuel ratio signal, wherein the output signal is also a function of the gas:fuel ratio signal.24. The control system of claim 1 wherein the process gas stream is the fuel.25. The control system of claim 24 wherein the first flow rate is the mass flow rate of the fuel into the reformer.26. The control system of claim 1 wherein the process gas stream is the reformate stream and the first flow rate is the volumetric flow rate of the reformate.27. The control system of claim 26 wherein the first sensor measures a hydrogen concentration.28. A control system for a fuel cell electric power generation system having a fuel processing system comprising a reformer for converting a reactant stream comprising a hydrocarbon fuel to a reformate stream, and a fuel cell stack fluidly connected to the fuel processing system to receive the reformate stream, the control system comprising:a current detector for measuring an output current of the fuel cell stack; a flow detector for measuring a flow rate indicative of a fuel flow rate into the reformer; a methane sensor for measuring methane concentration in the reformate stream; and a processor for determining hydrogen utilization in the fuel cell stack using signals from the current detector, flow detector, and methane sensor, and for comparing the determined hydrogen utilization against a selectable value and generating a processor signal for adjusting a control variable impacting hydrogen utilization, the processor signal being generated as a function of a difference between the selectable value and the determined hydrogen utilization. 29. The control system of claim 28 further comprising an output current regulator, and wherein the control variable is the output current regulator.30. The control system of claim 28 further comprising a flow control element for controlling the fuel flow rate into the reformer, wherein the control variable is the flow control element.31. The control system of claim 28 wherein the selectable value is set between about 80% and about 85%.32. The control system of claim 28 wherein the selectable value is set at about 80%.33. A fuel cell electric power generation system comprising:a reformer with an inlet passage for receiving a reactant stream comprising a fuel stream and an outlet passage to allow a reformate stream to exit the reformer; a fuel cell stack with an anode inlet passage fluidly connected to the outlet passage of the reformer; a methane sensor for measuring a concentration of methane in the reformate; a flow detector for measuring a flow rate of the fuel stream or the reformate stream; a current detector for measuring an output current of the fuel cell stack; and a controller configured to process a signal from the methane sensor, a signal from the flow detector, and a signal from the current detector to control a process variable for maintaining hydrogen utilization in the fuel cell stack at about a selectable value or within a selectable range. 34. The power generation system of claim 33 wherein the methane sensor is an IR sensor.35. The power generation system of claim 33 wherein the process variable is the output current of the fuel cell stack.36. The power generation system of claim 33 wherein the process variable is the flow rate of the reactant stream.37. The power generation system of claim 33 wherein the process variable is the flow rate of the fuel stream.38. The power generation system of claim 33 wherein the selectable range is set at about 70% to about 95%.39. The power generation system of claim 33 wherein the selectable range is set at about 80% to about 85%.40. The power generation system of claim 33 wherein the selectable value is set at about 80%.41. A method of controlling a fuel cell electric power generation system having a fuel processing system comprising a reformer for converting a reactant stream comprising a fuel stream to a reformate stream, and a fuel cell stack fluidly connected to the fuel processing system to receive the reformate stream, the method of control comprising:measuring a flow rate of the fuel stream or the reformate stream; measuring a methane concentration of the reformate stream using an IR methane sensor; calculating a hydrogen flow rate to the fuel cell stack using the measured flow rate and the methane concentration of the reformate stream, and a maximum allowable output current based on the hydrogen flow rate; measuring the output current of the fuel cell stack; and adjusting the output current of the fuel cell stack to approximately match the maximum allowable output current. 42. The method of claim 41 wherein the maximum allowable output current is determined on the basis of hydrogen utilization by the fuel cell stack of between about 70% and about 95%.43. The method of claim 41 wherein the maximum allowable output current is determined on the basis of hydrogen utilization by the fuel cell stack of about 90%.44. The method of claim 41 wherein the maximum allowable output current is determined on the basis of hydrogen utilization by the fuel cell stack of between about 80% and about 85%.45. A method of controlling a fuel cell electric power generation system having a fuel processing system comprising a reformer for converting a reactant stream comprising a fuel stream to a reformate stream, and a fuel cell stack fluidly connected to the fuel processing system to receive the reformate stream, the method of control comprising:measuring a flow rate of the fuel stream or the reformate stream; measuring a methane concentration of the reformate stream using an IR methane sensor; measuring an output current of the fuel cell stack; selecting a hydrogen utilization for the fuel cell stack; determining a fuel flow rate set point necessary to achieve the selected hydrogen utilization based on the output current and methane concentration; and adjusting the flow rate of the reactant stream or the fuel stream to approximate the fuel flow rate set point. 46. The method of claim 45 wherein the selected hydrogen utilization is between about 70% and about 95%.47. The method of claim 45 wherein the selected hydrogen utilization is about 90%.48. The method of claim 45 wherein the selected hydrogen utilization is about 80%.49. The method of claim 45 wherein the selected hydrogen utilization is about 70%.