초록 ▼

A fuel cell power plant system (10) having a membrane/electrode assembly (MEA) (21,22,23) fuel cell stack (11) is provided with the method and means for inerting the MEA through use of the coolant to effect a purge. Under normal on load operation, fuel flows through a fuel reactant flow path (30) at

A fuel cell power plant system (10) having a membrane/electrode assembly (MEA) (21,22,23) fuel cell stack (11) is provided with the method and means for inerting the MEA through use of the coolant to effect a purge. Under normal on load operation, fuel flows through a fuel reactant flow path (30) at the anode side(s) of the stack (11), oxidant flows through an oxidant reactant flow path (29) at the cathode side(s) of the stack (11), and the coolant, typically water, flows through the coolant flow path (32,31) of the stack (11). However, during transient operations of shutdown and/or start-up, the coolant is at least temporarily redirected to one, or both, of the fuel and the oxidant reactant flow paths (30/29) in lieu of their respective supplies of fuel and oxidant. This serves to purge the respective reactant(s) from the respective flow path(s). To provide sufficient supply of coolant for the purge, the supply of coolant to the coolant flow path (32,31) may be reduced or terminated. The control of flow of the reactants and coolant is accomplished via a network of valved fluid conduits (43,44,47,48,52,54,52',54',52′,54′,64,66,62, 70,64′,66′,60,68,64',66'), typically under direction of an automatic controller (72). Coolant sensors (80,82) positioned near the outlets of the reactant flow paths from stack (11) may indicate the arrival of coolant at those respective outlets to effect an appropriate control action.

대표청구항 ▼

1. A method of purging a fuel cell stack (11) in a fuel cell power plant system (10) during at least one of the two transient operations of shutdown and start-up, the fuel cell stack (11) having a membrane/electrode assembly (MEA)(21,22,23), which MEA includes anode (23) and cathode (22) electrodes

1. A method of purging a fuel cell stack (11) in a fuel cell power plant system (10) during at least one of the two transient operations of shutdown and start-up, the fuel cell stack (11) having a membrane/electrode assembly (MEA)(21,22,23), which MEA includes anode (23) and cathode (22) electrodes on respectively opposite sides of the membrane electrolyte (21), the stack (11) having a fuel reactant flow path (30) on the anode side of the MEA, an oxidant reactant flow path (29) on the cathode side of the MEA, and a coolant flow path (32,31) on at least one of the anode and the cathode sides of the MEA, the fuel reactant flow path (30), the oxidant reactant flow path (29) and the coolant flow path (32,31) each having a respective inlet to (37,39,35) and a respective outlet from (38,40,46) the stack (11), and a fuel reactant supply (42), an oxidant reactant supply (46), and a coolant supply (50) being fed to the fuel reactant inlet (37), the oxidant reactant inlet (39), and the coolant inlet (35), respectively, during normal on load operation of the fuel cell stack (11) in the system (10), the purging method comprising:(a) feeding the coolant supply (50) to at least one of the fuel reactant inlet (37) and the oxidant reactant inlet (39) in the absence of feed of the fuel reactant supply (42) and the oxidant reactant supply (46) to the respective inlets, and (b) causing the coolant to flow in and thereby purge the respective at least one fuel reactant flow path (30) and oxidant reactant flow path (29).