Abstract: Fuel mixing control arrangements are provided for fuel cell power plants (10) operating on multiple fuels (22, 24, 26). A fuel delivery system (16) supplies hydrogen-rich fuel (20) to the cell stack assembly (CSA) (12) after controlled mixing of a primary fuel (22) and at least a secondary fuel (24), each having a respective “equivalent hydrogen (H2) content”. The relative amounts of the primary fuel (22) and secondary fuel (24) mixed are regulated (18, 34, 36) to provide at least a minimum level (LL) of hydrogen-rich fuel having an equivalent hydrogen content sufficient for normal operation of the CSA (12). The primary fuel (22) is a bio-gas or the like having a limited, possibly variable, equivalent H2 content, and the secondary fuel (22) has a greater and relatively constant equivalent H2 content and is mixed with the primary fuel in an economic, constant relationship that assures adequate performance of the CSA (12). One or more parameters (IDC, P, V, E. C.

Abstract: Fuel mixing control arrangements are provided for fuel cell power plants (10) operating on multiple fuels (22, 24, 26). A fuel delivery system (16) supplies hydrogen-rich fuel (20) to the cell stack assembly (CSA) (12) after controlled mixing of a primary fuel (22) and at least a secondary fuel (24), each having a respective “equivalent hydrogen (H2) content”. The relative amounts of the primary fuel (22) and secondary fuel (24) mixed are regulated (18, 34, 36) to provide at least a minimum level (LL) of hydrogen-rich fuel having an equivalent hydrogen content sufficient for normal operation of the CSA (12). In one embodiment, the primary fuel (22) is a bio-gas or the like having a limited, possibly variable, equivalent H2 content, and the secondary fuel (22) has a greater and relatively constant equivalent H2 content and is mixed with the primary fuel in an economic, constant relationship that assures adequate performance of the CSA (12).

Abstract: An improved water management system for PEM fuel cells is provided. Catalyst layers are disposed on both sides of a proton exchange membrane. Porous plates are positioned adjacent the catalyst layers. Water transport plates are positioned adjacent the porous plates and the reactant gas are humidified at their inlets, in one embodiment by fins, while moisture is removed in the fuel flow path and at the oxidant outlet, in one embodiment by other fins.

Abstract: The invention is a bi-zone water transport plate for a fuel cell wherein the plate includes a water permeability zone and a bubble barrier zone. The bubble barrier zone extends between all reactive perimeters of the plate, has a pore size of less than 20 microns, and has a thickness of less than 25 percent of a shortest distance between opposed contact surfaces of the plate. The water permeability zone has a pore size of at least 100 percent greater than the pore size of the bubble barrier zone, and has a thickness of greater than 75 percent of the shortest distance between the opposed contact surfaces of the plate. By having a separate bubble barrier zone, the plate affords enhanced water permeability while the bubble barrier maintains a gas seal.

Abstract: The invention is a bi-zone water transport plate for a fuel cell wherein the plate includes a water permeability zone and a bubble barrier zone. The bubble barrier zone extends between all reactive perimeters of the plate, has a pore size of less than 20 microns, and has a thickness of less than 25 percent of a shortest distance between opposed contact surfaces of the plate. The water permeability zone has a pore size of at least 100 percent greater than the pore size of the bubble barrier zone, and has a thickness of greater than 75 percent of the shortest distance between the opposed contact surfaces of the plate. By having a separate bubble barrier zone, the plate affords enhanced water permeability while the bubble barrier maintains a gas seal.

Abstract: An improved water management system for PEM fuel cells is provided. Catalyst layers are disposed on both sides of a proton exchange membrane. Porous plates are positioned adjacent the catalyst layers. Water transport plates are positioned adjacent the porous plates and the reactant gas are humidified at their inlets, in one embodiment by fins, while moisture is removed in the fuel flow path and at the oxidant outlet, in one embodiment by other fins.

Abstract: The concentration of carbon monoxide in a gaseous medium is reduced by selective catalytic oxidation in the presence of gaseous oxygen by passing the gaseous medium through a catalyst capable of oxidizing carbon monoxide in an exothermic reaction at temperatures within a given temperature range and by controlling the temperatures encountered in the catalyst in such a manner that the exothermic reaction takes place first above a threshold temperature below which the catalyst would be rapidly inactivated at the relatively high carbon monoxide concentrations present in the gaseous medium as it enters the catalyst, and subsequently, after the carbon monoxide concentration has been reduced to an acceptable level, at less than the threshold temperature to further reduce the carbon monoxide concentration to a desired minimum level below that achievable at temperatures above the threshold temperature.

Abstract: The effluent gas stream from anaerobic waste water treatment digesters is treated to remove trace amounts of hydrogen sulfide and other contaminants. The chemical equation involved relies on the reaction of hydrogen sulfide with oxygen to form water plus elemental sulfur. The removal system includes a variable control line for adding air to the effluent gas stream; a filter for removing solids, entrained liquids and bacteria from the oxygen-enriched gas stream; a blower for directing the filtered gas stream into a potassium promoted activated carbon bed wherein the above chemical reaction takes place; and sensors for measuring the content of oxygen and hydrogen sulfide at the entrance and exit of the activated carbon bed. When the hydrogen sulfide content of the exiting gas stream exceeds a predetermined level, the amount of air added to the gas stream is increased until the predetermined level of hydrogen sulfide is achieved in the exiting gas stream.

Abstract: The effluent gas stream from anaerobic waste water treatment digesters is treated to remove trace amounts of hydrogen sulfide and other contaminants. The chemical equation involved relies on the reaction of hydrogen sulfide with oxygen to form water plus elemental sulfur. The removal system includes a variable control line for adding air to the effluent gas stream; a filter for removing solids, entrained liquids and bacteria from the oxygen-enriched gas stream; a blower for directing the filtered gas stream into a potassium promoted activated carbon bed wherein the above chemical reaction takes place; and sensors for measuring the content of oxygen and hydrogen sulfide at the entrance and exit of the activated carbon bed. When the hydrogen sulfide content of the exiting gas stream exceeds a predetermined level, the amount of air added to the gas stream is increased until the predetermined level of hydrogen sulfide is achieved in the exiting gas stream.

Abstract: The gas stream which is produced in and emanates from landfills, anaerobic digesters and other waste gas streams, is treated to produce a purified gas which is essentially a hydrocarbon such as methane and which can be used as the fuel source in a fuel cell power plant. The gas stream passes through a simplified purification system which removes essentially all of the sulfur compounds, hydrogen sulfide, and halogen compounds from the gas stream. The resultant gas stream can be used to power a fuel cell power plant which produces electricity, or as a hydrocarbon fuel gas for other applications.

Abstract: The gas stream which emanates from landfills is treated to produce a purified gas which is essentially a hydrocarbon such as methane which can be used as the fuel source in a fuel cell power plant, or can be used in other power plants which use natural gas as a fuel. The landfill gas passes through a system which removes essentially all of the hydrogen sulfide; water; organic sulfur and halogen compounds; and solid contaminants from the gas stream. The resultant purified gas stream can be cleanly flared; used to power an energy plant; or put to other useful purposes.

Abstract: The concentration of carbon monoxide in a gaseous medium is reduced by selective catalytic oxidation in the presence of gaseous oxygen by passing the gaseous medium through a catalyst capable of oxidizing carbon monoxide in an exothermic reaction at temperatures within a given temperature range and by controlling the temperatures encountered in the catalyst in such a manner that the exothermic reaction takes place first above a threshold temperature below which the catalyst would be rapidly inactivated at the relatively high carbon monoxide concentrations present in the gaseous medium as it enters the catalyst, and subsequently, after the carbon monoxide concentration has been reduced to an acceptable level, at less than the threshold temperature to further reduce the carbon monoxide concentration to a desired minimum level below that achievable at temperatures above the threshold temperature.

Abstract: High-purity nitrogen gas is generated by reducing at least the residual oxygen content of at least the cathode exhaust gas stream of a fuel cell device. The oxygen reduction is achieved either by controlling the passage of an oxidant gas through the cathode side of the fuel cell device in such a manner as to increase the oxygen utilization at the cathode side of the fuel cell device relative to the optimum electric power generation operating conditions of the fuel cell device, or by removing most of the residual oxygen from the cathode exhaust gas stream exhausted from the cathode side of the fuel cell device, while maintaining both oxygen and nitrogen contained in the cathode exhaust gas in their gaseous states throughout, or both. Moreover, anode exhaust gas can be reacted in a reformer burner with a reduced amount of excess oxygen and/or the reformer burner exhaust gas can be purified to remove combustion products and/or oxygen therefrom.

Abstract: An arrangement for replenishing hydrogen consumed in a fuel cell device includes a reaction vessel that contains a quantity of a material that releases hydrogen on contact with water in a highly exothermic reaction. A hydrogen-containing gaseous medium is passed through the material quantity under conditions resulting in removal of heat from the material quantity by convection at a heat removal rate sufficient to maintain a temperature differential between an inlet portion and an outlet portion of the reaction vessel below a predetermined level. This includes recirculating a portion of the gaseous medium from the outlet portion to the inlet portion and cooling at least the recirculated portion.

Abstract: The cell stack can be operated as a fuel cell stack or as an electrolysis cell stack. The stack consists of a series of alternate fuel cell subassemblies with intervening electrolysis cell subassemblies, and interspersed cooling plates. The water produced and consumed in the two modes of operation migrates between adjacent cell subassemblies. The component plates are annular with a central hydrogen plenum and integral internal oxygen manifolds. No fluid pumps are needed to operate the stack in either mode.

Abstract: A seal structure 60 for a porous plate of an electrochemical cell, such as plates 18, 20, includes a sealing material disposed in a seal region 66 of the plate to form a hydrophilic barrier to gas with an electrolyte and a hydrophobic layer 62 to block the loss of electrolyte from the hydrophilic layer is disclosed. Various construction details including a method for making the plate are disclosed which increase the cross pressure the sealing region of the plate can withstand. In one embodiment, the seal region 66 is impregnated with powder having a low structure and predetermined particle size using a pressurized liquid carrier. A FEP Teflon film bonds adjacent electrolyte reservoir plates together.

Abstract: Molten carbonate fuel cell cathodes formed from a composition comprising oxides of nickel, lithium salts and barium salts having improved strength. These cathodes are fabricated by prefiring oxides of nickel and optionally lithium salts. The prefired powder is optionally leached with an organic acid and optional barium salts may be added. These powders are formed into an electrode and sintered. The resulting electrodes have improved strength.

Abstract: An efficient process for the production of nitrogen from air using a fuel cell to provide both electrical power and an oxygen depleted gas stream to a liquefaction apparatus is disclosed. An apparatus for the production of nitrogen incorporating a fuel cell is also disclosed.

Abstract: Spaced based burst power fuel cells generate large thermal loads in very short time periods. In order to avoid external venting or the use of heavy radiators in space vehicles, such fuel cells must include onboard closed-loop cooling systems. Utilizing subcooled ice as a cooling medium, contactable with either the anode, cathode or coolant recirculating stream provides the fuel cell with a safe, highly efficient and low weight heat absorption capability.

Abstract: An efficient process for the production of nitrogen from air using a fuel cell to provide both electrical power and an oxygen depleted gas stream to a liquefaction apparatus is disclosed. An apparatus for the production of nitrogen incorporating a fuel cell is also disclosed.