Patent ID: 8277991

Claim:
A passive hydrogen bleed hydrogen passivation shut-down system for a fuel cell power plant ( 200 ), the system comprising: a. at least one fuel cell ( 12 ′) for generating electrical current from hydrogen containing reducing fluid fuel and oxygen containing oxidant reactant streams, the fuel cell ( 12 ′) including an anode catalyst ( 14 ′) and a cathode catalyst ( 16 ′) on opposed sides of an electrolyte ( 18 ′), an anode flow path ( 24 ′) in fluid communication with the anode catalyst ( 14 ′) for directing the hydrogen fuel to flow through the fuel cell ( 12 ′) and adjacent the anode catalyst ( 14 ′), and a cathode flow path ( 38 ′) in fluid communication with the cathode catalyst ( 16 ′) for directing the oxidant stream to flow through the fuel cell ( 12 ′) and adjacent the cathode catalyst ( 14 ′); b. a hydrogen inlet valve ( 52 ′) secured in fluid communication with a hydrogen feed line ( 55 ′) that is secured between a fuel source ( 54 ′) and the anode catalyst ( 14 ′) for selectively directing flow of the hydrogen fuel from the fuel source ( 54 ′) through the feed line ( 55 ′) and hydrogen inlet valve ( 52 ′) to the anode catalyst ( 14 ′); c. an oxidant inlet valve ( 56 ′) secured in fluid communication with an oxidant feed line ( 62 ′) extending between an oxidant supply source ( 58 ′) and the cathode flow field ( 42 ′); d. hydrogen transfer means secured in communication between the anode flow path ( 24 ′) and the cathode flow path ( 38 ′) for selectively permitting transfer of the hydrogen fuel between the anode flow path ( 24 ′) and the cathode flow path ( 38 ′); and, e. a passive hydrogen bleed line ( 202 ) secured to the hydrogen fuel source ( 54 ′) and extending from the hydrogen fuel source ( 54 ′) to be secured to the anode flow path ( 24 ′) at a location on the anode flow path ( 24 ′) that is between the hydrogen inlet valve ( 52 ′) and the anode catalyst ( 14 ′), the passive hydrogen bleed line ( 202 ) consisting of a diffusion media ( 204 ) secured within a chamber ( 206 ) and a through flow defined by the passive hydrogen bleed line ( 202 ) for permitting consistent flow of the hydrogen from the hydrogen fuel source ( 54 ′) through the diffusion media ( 204 ) to the anode flow path ( 24 ′), wherein the passive hydrogen bleed line ( 202 ) is configured to permit passage through the bleed line ( 202 ) of hydrogen from the hydrogen fuel source ( 54 ′) to the anode flow path ( 24 ′) when the hydrogen inlet valve ( 52 ′) is in either of a closed position and an open position, and the passive hydrogen bleed line ( 202 ) is also configured to permit passage of hydrogen from the hydrogen fuel source ( 54 ′) to the anode flow path ( 24 ′) through the bleed line ( 202 ) of a lowest flow rate of hydrogen necessary to maintain the fuel cell ( 12 ′) in a passive state.