Abstract: In a fuel cell system, a reformer supplies reformate to a fuel cell stack. A portion of the reformate flow is diverted for analysis by a hydrocarbon analysis system. Residual hydrocarbons in the reformate may damage the anodes of the fuel cell stack. Although incompletely-reformed reformate may include a variety of hydrocarbon compounds, the invention simply measures methane as an indicator of the overall performance level of the reformer. A currently preferred embodiment includes a catalytic combustion methane sensor. Combustion air and reformate are delivered in a fixed ratio to the sensor via positive displacement pumps. The system can provide alarm means or optionally a shut-off means to protect a fuel cell stack from elevated levels of hydrocarbons in the reformate stream.

Abstract: In a fuel cell system, a reformer supplies reformate to a fuel cell stack. A portion of the reformate flow is diverted for analysis by a hydrocarbon analysis system. Residual hydrocarbons in the reformate may damage the anodes of the fuel cell stack. Although incompletely-reformed reformate may include a variety of hydrocarbon compounds, the invention simply measures methane as an indicator of the overall performance level of the reformer. A currently preferred embodiment includes a catalytic combustion methane sensor. Combustion air and reformate are delivered in a fixed ratio to the sensor via positive displacement pumps. The system can provide alarm means or optionally a shut-off means to protect a fuel cell stack from elevated levels of hydrocarbons in the reformate stream.

Abstract: A fuel cell system includes a fuel cell stack that generates electrical energy during operation by reacting two streams of reactant gases. The fuel cell stack also produces a fuel cell exhaust stream. An oxidizer unit is positioned to receive the fuel cell exhaust stream. The oxidizer unit oxidizes at least a part of the fuel cell exhaust stream in an oxidizing gas stream during operation. A temperature sensor is positioned to sense a temperature of the oxidizer unit and an input system provides the oxidizer unit with at least the stoichiometric amount of the oxidizing gas stream during operation. The input system controls the amount of the oxidizing gas stream in excess of the stoichiometric amount provided to the oxidizer unit in response to the temperature of the oxidizer unit.

Abstract: A fuel cell system includes a fuel cell stack that generates electrical energy during operation by reacting two streams of reactant gases. The fuel cell stack also produces a fuel cell exhaust stream. An oxidizer unit is positioned to receive the fuel cell exhaust stream. The oxidizer unit oxidizes at least a part of the fuel cell exhaust stream in an oxidizing gas stream during operation. A temperature sensor is positioned to sense a temperature of the oxidizer unit and an input system provides the oxidizer unit with at least the stoichiometric amount of the oxidizing gas stream during operation. The input system controls the amount of the oxidizing gas stream in excess of the stoichiometric amount provided to the oxidizer unit in response to the temperature of the oxidizer unit.

Abstract: A fuel cell system includes a fuel cell stack, which during operation generates electrical energy by reacting a first stream of reactant gas and a second stream of reactant gas. The fuel cell stack also produces a fuel cell exhaust stream. An oxidizer unit is positioned to receive the fuel cell exhaust stream and oxidize at least a part of the fuel cell exhaust stream during operation, to produce an oxidizer exhaust stream. A heat recovery system is positioned to receive the oxidizer exhaust stream. The heat recovery system transfers at least some heat from the oxidizer exhaust stream to an input stream to generate a heated stream of water. In some embodiments, a temperature sensor is positioned to sense the temperature of the heated input stream. A control system maintains the heated stream of water at a target temperature based on the sensed temperature by controlling the amount of the heat from the oxidizer exhaust stream that is transferred to the input stream.