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:
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 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:
An electrical interconnect for a solid-oxide fuel cell stack assembly, including a novel sintering paste and an improved manufacturing process for an anode and cathode electrical contacts is disclosed. On the anode side, the paste contains a metallic oxide such as NiO, and an amount of sacrificial pore-forming particles, such as carbon particles or polymer spheres, which are vaporized during sintering of the paste, resulting in a very porous connection having good electrical conductivity and good adhesion. A preferred level of pore-former in the paste is about 40 volume percent. On the cathode side, the paste contains a noble metal such as for example, gold, platinum, palladium or rhodium, and an amount of the sacrificial pore-forming particles. The paste may be applied to the surfaces in a grid pattern or, because the resulting contact is porous after sintering, it may be applied as a continuous layer.
摘要:
A method of starting a solid oxide fuel cell system is disclosed. The method comprises pressurizing a main plenum to a first pressure. The main plenum comprises a first supply of fuel, blowers, and air control valves. The first supply of fuel and a first supply of air are directed to a preheated micro-reformer. A heated pre-reformate is created in the micro-reformer and discharged from the micro-reformer to a main reformer. The main reformer is preheated with the heated pre-reformate. A second supply of fuel and a second supply of air are introduced to the main reformer. A heated main reformate is created in the main reformer and directed to a waste energy recovery assembly. A cathode supply is heated in the waste energy recovery system and then directed to a solid oxide fuel cell stack in order to heat the solid oxide fuel cell stack. Methods of transitioning, operating, shutting down, and maintaining in standby mode are also disclosed. A solid oxide fuel cell mechanization for a transportation vehicle is also disclosed.
摘要:
A fuel cell assembly comprising a plurality of individual fuel cells, especially a solid-oxide fuel cell assembly. The cells are organized into a plurality of stacks, preferably two stacks, disposed side-by-side rather than end-to-end as in a prior art monolithic single stack. This arrangement makes the assembly compact physically, which can be highly desirable in some fuel cell applications. The stacks are connected conventionally in series electrically but are supplied with air and fuel in parallel to shorten the distribution manifolds and improve uniformity of distribution and exhaust among all the cells.
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 modular fuel cell cassette for use in assembling a fuel cell stack comprising a metal separator plate and a metal cell-mounting plate joined at their edges to form a hollow cassette. A fuel cell subassembly is attached to the mounting plate and extends through an opening in the mounting plate. The plates include openings to form chimney manifolds for supply and exhaust of fuel gas to the anode and air to the cathode. A conductive interconnect element extends from the fuel cell subassembly to make contact with the next cassette in a stack. The anode openings in the mounting plate and separator plate are separated by spacer rings such that the cassette is incompressible. A fuel cell stack comprises a plurality of cassettes, the mounting plate of one cassette being attached to, and insulated from, the separator plate of the next-adjacent cassette by a dielectric seal surrounding the interconnect.