Abstract: A method for operating a fuel cell power plant to provide end-use electricity, end-use heat and end-use reformate includes the steps of providing a fuel cell power plant that consumes reformate to provide electricity and heat, said fuel cell power plant having a nominal reformate flow rate and including a fuel processor system for generating reformate from a hydrocarbon fuel; operating the fuel processor system so as to provide a reformate flow at a rate greater than the nominal reformate flow rate; operating the fuel cell power plant using a first portion of the reformate flow to generate the electricity and the heat, the first portion being less than or equal to the nominal reformate flow rate; and providing a second portion of the reformate flow as the end-use reformate.

Abstract: A fuel cell stack (30) includes an integrated end plate assembly having a current collector (40) secured adjacent and end cell (36) of the stack, a pressure plate (42) secured adjacent the current collector (40), and a backbone (60) secured within a backbone-support plane (44) defined within the plate (42). Tie rod ends (62, 64, 66, 68) of the backbone (60) extend over a gap (84) defined between the backbone-support plane (44) and a deflection plane (50) defined within the pressure plate (42) so that the tie rod ends deflect within the gap (84) upon tightening of tie rods (78, 80). Deflection of the backbone enables the backbone (60) to permit limited expansion of the fuel cell stack (30) during operation, and the backbone (60) has adequate flexural strength to prohibit expansion of the stack (30) beyond operating dynamic limits of the stack (30).

Abstract: A bipolar plate (30) for use in a fuel cell stack (10) includes one or more first metal layers (40a) having a tendency to grow an electrically passive layer in the presence of a fuel cell reactant gas and one or more second metal layers (40b) directly adjacent the one or more first metal layers (40a). The second metal layer has a tendency to resist growing any oxide layer in the presence of the fuel cell reactant gas to maintain a threshold electrical conductivity. The second metal layer also has a section for contacting an electrode (12, 14) and providing an electrically conductive path between the electrode (12, 14) and the first metal layer.

Abstract: A separator scrubber (58) and isolation loop (78) decontaminates a fuel reactant stream of a fuel cell (12). Water passes over surfaces of an ammonia dissolving means (61) within the scrubber (58) while the fuel reactant stream simultaneously passes over the surfaces to remove contaminants from the fuel reactant into the water. An accumulator (68) collects the separated contaminants and water, and an isolation loop pump (84) directs flow of the separated contaminant stream through the isolation loop (78). A heat exchanger (86) and an ion exchange bed (88) modify the heat of, and remove contaminants from, the separated contaminant stream, and the isolation loop (78) directs the decontaminated stream back onto the packed bed (62)-. Separating contaminants from the fuel reactant stream and then isolating and concentrating the separated contaminants within the ion exchange bed (88) minimizes cost and maintenance requirements.

Abstract: A method for making a membrane electrode assembly includes the steps of providing a membrane electrode assembly including an anode including a hydrogen oxidation catalyst; a cathode; a membrane disposed between the anode and the cathode; and depositing a peroxide decomposition catalyst in at least one position selected from the group consisting of the anode, the cathode, a layer between the anode and the membrane and a layer between the cathode and the membrane wherein the peroxide decomposition catalyst has selectivity when exposed to hydrogen peroxide toward reactions which form benign products from the hydrogen peroxide. The peroxide decomposition catalyst can also be positioned within the membrane. Also disclosed is a power-generating fuel cell system including such a membrane electrode assembly, and a process for operating such a fuel cell system.

Abstract: A seal assembly for a solid oxide fuel cell stack, includes at least two fuel cell stack components having opposed surfaces and a seal member disposed between the surfaces, wherein the seal member is a compliant seal member that is mechanically compliant in both in-plane and out-of-plane directions relative to the surfaces. The seal member is advantageously formed of one or more substantially continuous fibers. Further, preferred materials for the seal member are provided which advantageously allow for a desired level of impermeability while preventing contamination of the fuel cell stack.

Abstract: A decontamination procedure for a fuel cell power plant (10) includes operating the plant to produce electrical power for an operating period, and then terminating operation of the plant (10) for a decontamination period, and then, whenever optimal electrical production of a plant fuel cell (12) is reduced by at least 5% by contaminants adsorbed by fuel cell electrodes (24, 42), decontaminating the fuel cell (12) of the plant (10) during the decontamination period by oxidizing contaminants adsorbed by electrodes (24, 42) of the fuel cell. Oxidizing the contaminants may be accomplished by various steps including exposing the electrodes (24, 42) to flowing oxygen; to heated flowing oxygen; to a sequence of start-stop cycles; and, to varying controlled potentials.

Abstract: A fuel cell power plant includes a plurality of fuel cell stacks which are operatively associated with each other so that both the air stream and fuel stream for the stacks are shared by each of the stacks in the power plant. The air and fuel streams are fed into an initial stack stage in the power plant, and after the air and fuel streams pass through the initial stack stage, the fuel exhaust streams are then fed into one or more subsequent stack stages in the power plant. The fuel streams are passed from the initial fuel cell stack stage to the subsequent fuel cell stack stage by means of a common manifold on which each of the fuel cell stacks in the power plant is mounted. The common manifold fuel stream passages are thermally insulated so as to limit water condensation in the fuel stream passages. The manifold may also include water condensation collection traps which will withdraw any water condensate that does form in the fuel stream passages.

Abstract: A power plant (10) includes at least one fuel cell (12), a coolant loop (18) including a freeze tolerant accumulator (22) for storing and separating a water immiscible fluid and water coolant, a direct contact heat exchanger (56) for mixing the water immiscible fluid and the water coolant within a mixing region (72) of the heat exchanger (56), a coolant pump (21) for circulating the coolant through the coolant loop (18), a radiator loop (84) for circulating the water immiscible fluid through the heat exchanger (56), a radiator (86) for removing heat from the coolant, and a direct contact heat exchanger by-pass system (200). The plant (10) utilizes the water immiscible fluid during steady-state operation to cool the fuel cell and during shut down of the plant to displace water from the fuel cell (12) to the freeze tolerant accumulator (22).

Abstract: A cell stack assembly (102) coolant system comprises a coolant exhaust conduit (110) in fluid communication with a coolant exhaust manifold (108) and a coolant pump (112). A coolant inlet conduit (120) enables transportation of the coolant to the coolant inlet manifold. The coolant system further includes a bypass conduit (132) in fluid communication with the coolant exhaust manifold and the coolant inlet manifold, while a bleed valve (130) is in fluid communication with the coolant exhaust conduit and a source of gas. Operation of the bleed valve enables venting of the coolant from the coolant channels, and through a shut down conduit (124). An increased pressure differential between the coolant and reactant gases forces water out of the pores in the electrode substrates (107,109). An ejector (250) prevents air form inhibiting the pump. Pulsed air is blown (238,239,243,245) through the coolant channels to remove more water.

Abstract: A fuel cell includes a membrane electrode assembly (46) having a first reactant flow field (80) secured adjacent a first or second surface (48, 50) of the assembly (46) for directing flow of a first reactant adjacent the first or second surface of the assembly (46). The first reactant flow field (80) defines a plurality of two-pass circuits (82, 84, 86, 88), and each two-pass circuit (82) is in fluid communication with both a first reactant inlet (90) for directing the first reactant into the fuel cell (12), and with a first reactant outlet (92) for directing the first reactant out of the fuel cell (12). The plurality of two-pass circuits (82) facilitate water movement (112) toward the reactant inlet (90) to aid in passive maintenance of fuel cell (12) water balance.

Abstract: An apparatus for preferential oxidation of carbon monoxide in a reformate flow includes a reactor defining a flow path for a reformate flow; at least one catalyst bed disposed along the flow path; and a distributor for distributing oxygen from an oxygen source to the at least one catalyst bed, the distributor including a conduit positioned at least one of upstream of and through the at least one catalyst bed, the conduit having a sidewall permeable to flow of oxygen from within the conduit to the at least one catalyst bed.

Abstract: The plant (60) includes at least one fuel cell (10, 62) having a wetproofed anode support (20) and a cathode support (24) for directing reactant streams adjacent catalysts (14, 16). A porous anode cooler plate (26) has its fuel channels (28A, 28B, 28C, 28D) secured adjacent the anode support (20). A porous cathode water management plate (38) has its oxidant channels (40A, 40B, 40C, 40D) secured adjacent the cathode support (24). A direct antifreeze solution passes only through coolant channels (32A, 32B, 32C, 32D) of the anode cooler plate (26) so the solution cannot poison the catalysts (14, 16), while fuel cell product water flows passively through the water management plate (38) and water management channels (44A, 44B, 44C, 44D) defined in the plate (38) to humidify reactant streams and be discharged from the fuel cell (62).

Abstract: A liquid-gas separator assembly is used in separating gas bubbles from a liquid coolant. The assembly includes a cylindrical housing containing a central tube which is surrounded by an annular chamber. The annular chamber is defined by the outer surface of the central tube and the inner surface of the cylindrical housing. An inlet line injects a stream of the coolant from the fuel cell stack area of the power plant into the bottom of the central tube in a tangential flow pattern so that the coolant and gas bubble mixture swirls upwardly through the central tube. The swirling flow pattern of the coolant and gas bubble mixture causes the gas bubbles to separate from the liquid coolant. The gaseous component of the separated mixture is then expelled from the housing through an outlet in the upper portion of the housing, and the coolant liquid descends through the annular chamber to the bottom of the housing.

Abstract: A homogeneous ceria-based mixed-metal oxide, useful as a catalyst support, a co-catalyst and/or a getter has a relatively large surface area per weight, typically exceeding 150 m2/g, a structure of nanocrystallites having diameters of less than 4 nm, and including pores larger than the nanocrystallites and having diameters in the range of 4 to about 9 nm. The ratio of pore volumes, VP, to skeletal structure volumes, VS, is typically less than about 2.5, and the surface area per unit volume of the oxide material is greater than 320 m2/cm3, for low internal mass transfer resistance and large effective surface area for reaction activity. The mixed metal oxide is ceria-based, includes Zr and or Hf, and is made by a novel co-precipitation process. A highly dispersed catalyst metal, typically a noble metal such as Pt, may be loaded on to the mixed metal oxide support from a catalyst metal-containing solution following a selected acid surface treatment of the oxide support.

Abstract: A fuel cell system having a fuel cell stack (9) employing a phosphoric acid or other electrolyte, includes a non-reactive zone (11) in each of a group of fuel cells between corresponding coolant plates (55), the coolant entering the coolant plates in an area adjacent to the non-reactive zones (29–31). Each fuel cell has three-pass fuel flow fields, the first pass substantially adjacent to a third zone (13), remote from the first zone, the second pass substantially adjacent to a second zone contiguous with the first zone, the coolant flowing (33, 34) from a coolant inlet (29) through the first zone, to the far side of the second zone, and (37–41) from the near side of the second zone to the third zone and thence (45–50) to a coolant exit manifold (30), which assures temperatures above 150° C. (300° F.), to mitigate CO poisoning of the anode within the reactive zones, and assuring temperatures below 140° C. (280° F.

Abstract: The invention is a system (10) and method for determining a gas composition within a fuel cell (12) of a shut down fuel cell power plant. The system (10) includes at least one fuel cell (12), a sensor circuit (86) secured in electrical connection with the fuel cell (12), wherein the circuit (86) includes a power source (88), a voltage-measuring device (90), and a sensor circuit switch (92). The circuit (86) is secured so that the power source (88) may selectively deliver a pre-determined sensing current to the fuel cell (12) for a pre-determined sensing duration. The system (10) selectively admits the reducing fluid into an anode flow field (28) of the cell (12) whenever the sensor circuit (86) senses that a shut down monitoring voltage of the fuel cell (12) is the same as or exceeds a calibrated sensor voltage limit of the fuel cell (12).

Abstract: A fuel cell stack includes a plurality of fuel cells each having an anode layer, an electrolyte layer, and a cathode layer, the fuel cells each having a first effective thermal expansion coefficient; a plurality of bipolar plates positioned between adjacent fuel cells having an anode interconnect, a separator plate, and a cathode interconnect, the bipolar plates being positioned between adjacent fuel cells, wherein the anode interconnect is in electrical communication with the anode layer of one adjacent fuel cell, wherein the cathode interconnect is in electrical communication with the cathode layer of another adjacent fuel cell, and wherein at least one interconnect of the cathode interconnect and the anode interconnect has a second thermal expansion coefficient and is adapted to reduce strain between the at least one interconnect and an adjacent fuel cell due to differences between the first and second thermal expansion coefficients over repeated thermal cycles.

Abstract: The invention is a hydrogen passivation shut down system for a fuel cell power plant (10). An anode flow path (24) is in fluid communication with an anode catalyst (14) for directing hydrogen fuel to flow adjacent to the anode catalyst (14), and a cathode flow path (38) is in fluid communication with a cathode catalyst (16) for directing an oxidant to flow adjacent to the cathode catalyst (16) of a fuel cell (12). Hydrogen fuel is permitted to transfer between the anode flow path (24) and the cathode flow path (38). A hydrogen reservoir (66) is secured in fluid communication with the anode flow path (24) for receiving and storing hydrogen during fuel cell (12) operation, and for releasing the hydrogen into fuel cell (12) whenever the fuel cell (12) is shut down.

Abstract: A power system (8) is provided for economically supplying uninterrupted electrical power to one or more critical loads (14). One or more fuel cell power plants (18) provide one substantially continuous source of power, and a utility grid (10) provides another source of power. The fuel cell power plants (18) are adapted to be, and are, normally substantially continuously connected and providing power to, the critical load(s) (14). A rapidly-acting static switch (19) selectively connects and disconnects and reconnects the grid power supply (10) to the critical load(s) (14) and with the fuel cell power plant(s) (18) for abnormal and normal grid operation, respectively. A switch controller (49, 45) controls the state of the static switch (19) to connect the grid power source (10) with the critical load(s) (14) and the rapidly (less than 4 ms) make the disconnections and the reconnections.