Decontamination procedure for a fuel cell power plant

A decontamination procedure for a fuel cell power plant (10), wherein the plant (10) includes at least one fuel cell (12) for generating electrical power from hydrogen containing reducing fluid fuel and oxygen containing oxidant reactant streams, a power circuit (80) for directing the electrical power from the fuel cell (12) to a primary electrical load (82), the fuel cell (12) including an anode electrode (24) and a cathode electrode (42) on opposed sides of an electrolyte (48), an anode flow field (22) in fluid communication with the anode electrode (24) for directing the hydrogen fuel to flow through the fuel cell (12) and adjacent the anode electrode (24), and a cathode flow field (40) in fluid communication with the cathode electrode (42) for directing the oxidant stream to flow through the fuel cell (12) and adjacent the cathode electrode (42), the decontamination procedure comprising the steps of:

• a. operating the fuel cell power plant (10) to produce electrical power for an operating period by connecting the primary electrical load (82) to the fuel cell (12), directing a flow of the oxidant through the cathode flow (40) field, and directing a flow of the hydrogen fuel through the anode flow field (22);
• b. then, whenever electrical power production of the fuel cell (12) is reduced by at least 5% by contamination of the cathode electrode (42), terminating operation of the fuel cell (12) of the plant (10) for a decontamination period by disconnecting the electrical load (82) from the fuel cell (12);
• c. then, decontaminating the fuel cell (12) during the decontamination period by connecting a source of direct current voltage (90) to the anode and cathode electrodes (24, 42), and applying the direct current voltage to increase a potential of the cathode electrode (42) relative to the anode electrode (24) to between about 0.9 volts and about 1.6 volts, compared to a standard hydrogen reference electrode, to oxidize contaminants adsorbed on the cathode electrode (42) during the operating period.

A decontamination procedure for a fuel cell power plant (10), wherein the plant (10) includes at least one fuel cell (12) for generating electrical power from hydrogen containing reducing fluid fuel and oxygen containing oxidant reactant streams, a power circuit (80) for directing the electrical power from the fuel cell (12) to a primary electrical load (82), the fuel cell (12) including an anode electrode (24) and a cathode electrode (42) on opposed sides of an electrolyte (48), an anode flow field (22) in fluid communication with the anode electrode (24) for directing the hydrogen fuel to flow through the fuel cell (12) and adjacent the anode electrode (24), and a cathode flow field (40) in fluid communication with the cathode electrode (42) for directing the oxidant stream to flow through the fuel cell (12) and adjacent the cathode electrode (42), the decontamination procedure comprising the steps of:

• a. operating the fuel cell power plant (10) to produce electrical power for an operating period by connecting the primary electrical load (82) to the fuel cell (12), directing a flow of the oxidant through the cathode flow (40) field, and directing a flow of the hydrogen fuel through the anode flow field (22);
• b. then, whenever electrical power production of the fuel cell (12) is reduced by at least 5% by contamination of the anode electrode (24) and/or the cathode electrode (42), terminating operation of the fuel cell (12) of the plant (10) for a decontamination period by disconnecting the electrical load (82) from the fuel cell (12);
• c. then, decontaminating the fuel cell (12) during the decontamination period by terminating flow of the hydrogen fuel through the anode flow field (22) and then directing flow of an oxidant containing oxidant stream through the anode flow field (22);
• d. then, connecting a source of direct current voltage (90) to the anode and cathode electrodes (24, 42), and controlling application of the direct current voltage to the electrodes (24, 42) so that a voltage differential between the electrodes is limited to about 0.5 volts, and whenever the voltage differential increases to about 0.5 volts, then controlling application of the direct current voltage to reverse a direction of current flow from the direct current source (90) to the anode and cathode electrodes (24) 42);
• and,
• e. while controlling application of the direct current voltage to the electrodes (24, 42), directing a minimal flow of an oxygen containing oxidant stream through the anode flow field (22) and cathode flow field (40).