摘要:
In a fuel cell assembly, nickel-based anodes are readily oxidized when exposed to oxygen as may happen through atmospheric invasion of the assembly during cool-down following shutdown of the assembly. Repeated anode oxidation and reduction can be destructive of the anodes, leading to cracking and failure. To prevent such oxygen migration, check valves and oxygen getter devices containing oxygen-scavenging material such as metallic nickel are provided in the reformate passageways leading to and from the anodes. The check valves preferably are closed by gravity. Oxidation of the oxygen-gettering material is readily reversed through reduction by reformate when the assembly is restarted.
摘要:
In a fuel cell assembly, nickel-based anodes are readily oxidized when exposed to oxygen as may happen through atmospheric invasion of the assembly during cool-down following shutdown of the assembly. Repeated anode oxidation and reduction can be destructive of the anodes, leading to cracking and failure. To prevent such oxygen migration, oxygen getter devices containing oxygen-gettering material such as metallic nickel are provided in the fuel passageways leading to and from the anodes. Oxidation of the oxygen-gettering material is readily reversed through reduction by fuel when the assembly is restarted.
摘要:
A solid-oxide fuel cell system including an integrated reforming unit comprising a hydrocarbon fuel reformer; an integral tail gas and cathode air combustor and reformer heat exchanger; a fuel pre-heater and fuel injector cooler; a fuel injector and fuel/air mixer and vaporizer; a reforming air pre-heating heat exchanger; a reforming air temperature control valve and means; and a pre-reformer start-up combustor. The integration of a plate reformer, tail gas combustor, and combustor gas heat exchanger allows for efficient operation modes of the reformer, both endothermic and exothermic as desired. The combustor gas heat exchanger aids in temperature regulation of the reformer and reduces significant thermal gradients in the unit.
摘要:
A solid-oxide fuel cell system having “hot” components, e.g., the fuel cell stacks, the fuel reformer, tail gas combuster, heat exchangers, and fuel/air manifold, contained in a “hot zone” within a thermal enclosure intended specifically for minimizing heat transfer to its exterior and having no significant structural or protective function for its contents. A two-part clamshell arrangement allows all piping and leads which must pass through the enclosure to do so at the join line between the parts, thus eliminating need for ports and fittings in the thermal enclosure. A separate and larger structural enclosure surrounds the thermal enclosure, defining a “cool zone” outside the thermal enclosure for incorporation of “cool” components, e.g., the air supply system and the electronic control system, and providing structural protection for all components of the fuel cell system.
摘要:
A load frame with mechanical springs for providing compression to a fuel cell stack during assembly and operation of a fuel cell assembly. The stack assembly load frame includes a base plate for supporting the stack, a moveable spring holder above the stack, a retaining plate above the spring holder, and tubular supports or rods retaining the post-sintered spacing established by the applied load defining the spacing of the base plate from the retaining plate. A spring for maintaining compression in each stack is positioned between the spring holder and the retaining plate. The invention further comprises a method for assembling a fuel cell assembly to provide an adequate compressive load to the stack during assembly and operation.
摘要:
In a solid-oxide fuel cell system, a fuel/air manifold conveys air and tail gas fuel from the anodes in a fuel cell stack assembly to a tail gas combustor, producing a heated combustor exhaust having the highest mass flow in the system. The exhaust is passed through a heat exchanger to warm incoming cathode reaction air, and the exhaust is partially cooled by the exchange. From the heat exchanger, the exhaust gas is passed through a tempering jacket space surrounding the fuel cells in the stack. During start-up of the system, the exhaust gas is hotter than the stack and so the warm-up period is shortened. During normal operation of the system, the exhaust gas is cooler than the operating temperature and therefore cooling of the stack is assisted by contact with the exhaust gas.
摘要:
In a solid-oxide fuel cell system, an integrated air supply system provides oxygen for the fuel cell cathode reaction via a first air flow through a heat exchanger and a second air flow bypassing the heat exchanger, at least one of the first and second flows being throttled by a control valve responsive to a fuel cell control system, the flows subsequently being combined to provide air to the cathodes at a desired temperature.
摘要:
In a solid-oxide fuel cell system, a catalytic reformer unit provides reformate fuel for use by the cells in generating electricity. Both the reformer and the fuel cells require elevated temperatures for satisfactory operation. The reformer unit is provided with a combustion chamber and igniter ahead of the catalytic reformer plates such that, during start-up, fuel/air mixture normally destined for reformation may be ignited in the combustion chamber to provide a hot combustion exhaust which is fed through the catalytic reformer and the anode reformate flow spaces to assist in rapidly bringing the fuel cell system to operating temperature.
摘要:
In a solid-oxide fuel cell assembly, at least one positive displacement air supply (PDAS) pump supplies at least a portion of the air required for various functional air streams through the assembly. Mass air flow through each PDAS pump is readily controlled to a predetermined flow by controlling the rotational speed of the pump, obviating the need for an MAF sensor and control valve. Preferably, each different air stream through the assembly is controlled by its own PDAS pump, sized for the required flow, allowing each to operate at its optimal pressure and thereby minimizing the parasitic electrical cost of providing air to the SOFC assembly.
摘要:
A fuel cell assembly or system including flexible metal bellows elements in one or more tubes intended for carrying hot gases during operation of the assembly. The bellows elements include a tubing element having plurality of annular corrugated folds. Thermal expansion and contraction of rigid tubes and of the non-tubular elements of the assembly can lead to buckling, cracking, and failure of the tubes and failure of the assembly or system. The flexible bellows elements, having relatively low axial and radial spring rates thus are able to absorb thermal and vibrational dimensional changes in the assembly. In addition, the corrugations provide significant resistance to axial heat flow and large radiant surface area, thus increasing thermal isolation where desired between relatively hot and relatively cold regions of the assembly.