Methods of removing contaminants from a fuel cell electrode
First Claim
1. A method of optimizing a waveform of an electrical current applied to an electrode, comprising the steps of:
- applying an electrical current to an electrode of a device;
determining a waveform of the voltage or the current of the electrical current;
representing the waveform by mathematical expressions or numbers;
taking measurements of a function of the device associated with the application of the electrical current; and
varying the shape and frequency of the waveform to optimize the function of the device and thereby determine an optimized waveform of the electrical current to be applied to the electrode of the device.
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Accused Products
Abstract
A method of optimizing a waveform of an electrical current applied to an electrode includes the steps of: applying an electrical current to an electrode of a device; determining a waveform of the voltage or the current of the electrical current; representing the waveform by a mathematical description such as a number of points or an analytical function characterized by a number of unknown coefficients and a fixed number of known functions; measuring a function of the device associated with the application of the electrical current; feeding the waveform description and the measurements to an algorithm, which may be in a computer program or other calculating device including manual calculations, including an optimization routine which uses the points or coefficients as independent variables for optimizing the function of the device; and performing the calculations to determine values of the points or coefficients which optimize the function of the device, and thereby determine an optimized waveform of the electrical current to be applied to the electrode of the device.
17 Citations
70 Claims
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1. A method of optimizing a waveform of an electrical current applied to an electrode, comprising the steps of:
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applying an electrical current to an electrode of a device;
determining a waveform of the voltage or the current of the electrical current;
representing the waveform by mathematical expressions or numbers;
taking measurements of a function of the device associated with the application of the electrical current; and
varying the shape and frequency of the waveform to optimize the function of the device and thereby determine an optimized waveform of the electrical current to be applied to the electrode of the device. - View Dependent Claims (3, 5, 6, 7, 8, 9, 10, 22, 50, 51, 52)
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2. A method of optimizing a waveform of an electrical current applied to an electrode, comprising the steps of:
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applying an electrical current to an electrode of a device;
determining a waveform of the voltage or the current of the electrical current;
representing the waveform by a mathematical description such as a number of points or an analytical function characterized by a number of unknown coefficients and a fixed number of known functions;
measuring a function of the device associated with the application of the electrical current;
feeding the waveform description and the measurements to an algorithm, which may be in a computer program or other calculating device including manual calculations, including an optimization routine which uses the points or coefficients as independent variables for optimizing the function of the device; and
performing the calculations to determine values of the points or coefficients which optimize the function of the device, and thereby determine an optimized waveform of the electrical current to be applied to the electrode of the device. - View Dependent Claims (4)
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11. A method of removing contaminants from an anode of a fuel cell, comprising:
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applying an electrical current to the anode of the fuel cell; and
pulsing the voltage of the electrical current during the application, such that the overvoltage at the anode is negative during the pulses, and the overvoltage at the anode is positive between the pulses. - View Dependent Claims (12, 13, 23)
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14. A method of operating a fuel cell comprising:
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applying an overvoltage to the anode of the fuel cell by applying a voltage to the anode with respect to a reference electrode, where the fuel contains higher than 1 percent CO; and
varying the overvoltage between a low value normally used for power production and a high value sufficiently high for cleaning CO from the electrode. - View Dependent Claims (15, 16, 48, 49)
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17. A method of operating a fuel cell comprising:
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feeding a fuel to the fuel cell containing at least 1 percent of an electrochemically active contaminant; and
applying an overvoltage to an electrode of the fuel cell, and varying the overvoltage between a low value normally used for power production and a high value for cleaning the contaminant from the electrode. - View Dependent Claims (18)
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19. A pulsed anode of an electrical device operating at greater than 1 percent CO using a method of optimizing a waveform of an electrical current applied to the anode, the method comprising the steps of:
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applying an electrical current to the anode;
determining a waveform of the voltage or the current of the device;
representing the waveform by mathematical expressions or numbers;
taking measurements of a function of the device associated with the application of the electrical current; and
varying the shape and frequency of the waveform to optimize the function of the device and thereby determine an optimized waveform of the electrical current to be applied to the anode of the device. - View Dependent Claims (20)
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21. A fuel cell having a pulsed electrode including an oxidation pulse, and the fuel cell having a voltage booster to change the cell voltage during the oxidation pulse to a desired level.
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24. A fuel cell system comprising:
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a fuel cell having a pulsed electrode and operating with a fuel containing greater than 1 percent electrochemically active contaminant; and
a fuel processor that is simplified compared to a fuel processor required when the same fuel cell is used without pulsing. - View Dependent Claims (25)
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- 26. A method of operating a fuel cell where a contaminant is cleaned from an electrode, where the fuel cell during operation has a variation in anode and/or cathode overvoltage, the method comprising feeding back a portion of the current output of the fuel cell to a control circuit to vary the voltage waveform to maintain a desired current and cleaning the contaminant.
- 28. A method of cleaning an electrochemically active contaminant from an electrode of an apparatus used in an electrochemical process, in which the electrode is cleaned by oxidizing the contaminant so that another reaction can proceed on the electrode, where the apparatus during operation has a variation in electrode overvoltage, the method comprising feeding back a portion of the current output of the apparatus to vary the voltage waveform to simultaneously maintain a desired current and clean the contaminant.
- 29. A method of cleaning an electrochemically active contaminant from an electrode of an apparatus used in an electrochemical process, in which the electrode is cleaned by oxidizing the contaminant so that another reaction can proceed on the electrode, where the apparatus during operation has a variation in electrode overvoltage, the method comprising measuring the current or voltage across the anode and cathode of the device, and utilizing that measurement as the input to a device to vary a load impedance that is in parallel or series with the useful load of the device to vary the voltage or current waveform at the electrodes to simultaneously maintain a desired current and clean the contaminant.
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38. A method of removing contaminants from an electrode of a fuel cell, comprising applying an electrical energy to the electrode of the fuel cell in the form of small voltage pulses to excite natural oscillations in fuel cell voltage during operation of the fuel cell, the voltage pulses being applied at the same frequency as the natural oscillations or at a frequency different from the natural oscillations.
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39. A method of removing contaminants from an anode of a fuel cell, comprising applying an electrical current to the anode of the fuel cell in the form of small voltage pulses to excite natural oscillations in fuel cell voltage during operation of the fuel cell, the voltage pulses being applied at the same frequency as the natural oscillations or at a frequency different from the natural oscillations.
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40. A method of removing contaminants from an anode or cathode of a fuel cell, comprising:
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applying an electrical current to the anode or cathode of the fuel cell;
pulsing the voltage of the electrical current during the application; and
controlling the pulsing with a control function to create a waveform or a frequency of the pulsing that removes the contaminants and maximizes the power output from the fuel cell.
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41. A method of removing contaminants from an anode or cathode of a fuel cell, comprising:
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applying an electrical current to the anode or cathode of the fuel cell;
pulsing the voltage of the electrical current during the application, the pulsing exciting and maintaining a natural oscillation of the fuel cell system.
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42. A feedback control method of operating a fuel cell comprising applying voltage control to an anode of the fuel cell using the following algorithm:
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a) determining a mathematical model that relates the instantaneous coverage of hydrogen and carbon monoxide to the overvoltage applied to the anode;
b) forming an observer that relates the instantaneous coverage of the hydrogen and carbon monoxide to the measured current of the fuel cell;
c) driving the estimated carbon monoxide coverage to a low value by varying the overvoltage;
d) driving the estimated hydrogen coverage to a high value by varying the overvoltage; and
e) repeating steps a) through d) as necessary.
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43. A feedback control method of operating a fuel cell comprising applying voltage control to an anode of the fuel cell using the following algorithm:
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a) determining a mathematical model that relates the instantaneous coverage of hydrogen and carbon monoxide to the overvoltage applied to the anode;
b) forming an observer that relates the instantaneous coverage of the hydrogen and carbon monoxide to the measured current of the fuel cell;
c) prescribing a desired trajectory of the instantaneous coverage of the hydrogen and carbon monoxide as a function of time;
d) forming a set of mathematical relationships from steps a), b) and c) that allows the current to be measured, the overvoltage to be prescribed and the instantaneous carbon monoxide coverage and instantaneous hydrogen coverage to be predicted;
e) driving the carbon monoxide coverage to a low value by varying the overvoltage according to step d);
f) driving the hydrogen coverage to a high value by varying the overvoltage according to step d); and
g) repeating steps a) through f) as necessary. - View Dependent Claims (44, 45)
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46. A feedback control method of operating an electrochemical apparatus operated using a fuel containing an electrochemically active contaminant, the method comprising applying voltage control to an anode of the apparatus using the following algorithm:
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a) determining a mathematical model that relates the instantaneous coverage of fuel and contaminant to the overvoltage applied to the anode;
b) forming an observer that relates the instantaneous coverage of the fuel and contaminant to the measured current of the apparatus;
c) driving the estimated contaminant coverage to a low value by varying the overvoltage;
d) driving the estimated fuel coverage to a high value by varying the overvoltage; and
e) repeating steps a) through d) as necessary.
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47. A feedback control method of operating an electrochemical apparatus operated using a fuel containing an electrochemically active contaminant, the method comprising applying voltage control to an anode of the apparatus using the following algorithm:
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a) determining a mathematical model that relates the instantaneous coverage of fuel and contaminant to the overvoltage applied to the anode;
b) forming an observer that relates the instantaneous coverage of the fuel and contaminant to the measured current of the apparatus;
c) prescribing a desired trajectory of the instantaneous coverage of the fuel and contaminant as a function of time;
d) forming a set of mathematical relationships from steps a), b) and c) that allows the current to be measured, the overvoltage to be prescribed and the instantaneous contaminant coverage and instantaneous fuel coverage to be predicted;
e) driving the contaminant coverage to a low value by varying the overvoltage according to step d);
f) driving the fuel coverage to a high value by varying the overvoltage according to step d); and
g) repeating steps a) through f) as necessary.
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61. A method of operating a fuel cell to clean a contaminant from an electrode, comprising the steps of demanding a constant current from the fuel cell;
- maintaining the constant current demand to induce voltage oscillations in the electrode and cause an overvoltage condition in the electrode; and
removing the contaminant from the electrode. - View Dependent Claims (62, 63, 64, 65, 66)
- maintaining the constant current demand to induce voltage oscillations in the electrode and cause an overvoltage condition in the electrode; and
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67. A method of operating a fuel cell comprising:
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providing a fuel cell having a pulsed electrode having an electrochemically active contaminant thereon;
pulsing the electrode in the presence of fuel having greater than one percent of an electrochemically active contaminant;
oxidizing at least a portion of the fuel and at least a portion of the electrochemically active contaminant on the pulsed electrode;
providing power from both the fuel and the contaminant. - View Dependent Claims (68, 69)
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70. A method of operating a fuel cell comprising:
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feeding a fuel to the fuel cell;
producing an electrochemically active contaminant at an electrode from the fuel; and
applying an overvoltage to an electrode of the fuel cell, and varying the overvoltage between a low value normally used for power production and a high value for cleaning the contaminant from the electrode; and
producing power from both the fuel and the contaminant.
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Specification