Abstract:
A tubular catalytic reactor, such as for steam reforming a hydrocarbon feedstock to produce hydrogen, is disposed within a furnace and includes an annular first bed of reaction catalyst. A second bed of reaction catalyst is disposed coaxial with the first bed and inwardly thereof. Product gases from the first bed, without adding heat thereto, are passed through the second bed essentially adiabatically resulting in a substantial reduction in the amount of unreacted hydrocarbons heavier than methane which were present in the product gases leaving the first bed. The apparatus is compact and uses only the sensible heat in the reaction products leaving the first bed to reduce the level of unwanted hydrocarbons. Thus, in the process of the present invention, the reduction in the level of unwanted heavier hydrocarbons is accomplished in compact apparatus without burning additional fuel and without extracting additional heat energy from the furnace.
Abstract:
A fuel cell system is provided that is capable of operating at high temperatures and near-ambient pressure with partial humidification of air supplied to the fuel cell stack. The fuel cells of the stack incorporate gas diffusion barrier layers at the cathode side thereof. The system includes a cooling loop for circulating a liquid coolant through the stack. In some embodiments, an incoming air stream is partially humidified with water vapor transferred from a cathode exhaust stream in a gas-exchange humidifier or enthalpy wheel. In other embodiments, a cathode recycle is employed to partially humidify the incoming air. The humidity of the air and cathode exhaust streams is maintained below a stack saturation point. Methods of operating the fuel cell system are also provided.
Abstract:
A water recovery fuel cell system includes a fuel cell defining a cathode flow field including a cathode input port and a cathode output port, and an anode flow field including an anode input port and an anode output port A humidity exchange device defines a supply gas input port, a supply gas output port, a process exhaust gas input port and a process exhaust gas output port. The supply gas input port is to be coupled to a source of oxidant gas, and the supply gas output port is coupled to the fuel cell power plant oxidant air supply including the cathode input port of the fuel cell. The process exhaust gas output port communicates at a junction with the cathode output port and a combustor exhaust derived from the anode flow field of the fuel cell, and the exhaust gas output port communicates with a power plant exhaust conduit. A power plant exhaust path is defined from the cathode output port to the power plant exhaust conduit via the humidity exchange device. A water recovery condenser is disposed along the power plant exhaust path between the junction and the power plant exhaust conduit.
Abstract:
A control system and method for controlling a fuel processing system operational to produce a gas for a downstream process from a fuel, wherein the fuel processing system uses a plurality of fuel processing elements, a fuel input and a waste gas input, each of the fuel processing elements having an individual output and the plurality of fuel processing elements having a collective output, and wherein the downstream process has a waste gas output and a dynamic gas load demand. The control system includes a device for receiving communication from the downstream process indicative of the dynamic load demand and a device for controlling the collective output level of the gas in response to the dynamic load demand. The device for controlling is operative to at least one of substantially equally distribute the dynamic load demand among the plurality of fuel processing elements such that the individual outputs from each of the fuel processing elements are substantially equal to each other for forming the collective output and most efficiently distribute the dynamic load among the plurality of fuel processing elements such that at least one of the individual outputs contributes to the collective output.
Abstract:
The fuel gas reformer of a fuel cell power plant is provided with burner gas flow baffles which are annular in configuration, and which are concentric with the axis of the burner tube. The annular burner gas flow baffles form annular burner gas flow passages. The reformer has a plurality of annular arrays of catalyst filled tubes disposed in concentric rings about the burner tube. Each of the adjacent catalyst tube rings is separated from the next filled tube ring by one of the annular baffles. Burner gases are deflected downwardly and outwardly by the reformer housing top piece onto the catalyst filled tube rings. The baffles prevent inward flow of the burner gases and direct the burner gases uniformly downwardly along the catalyst filled tubes. Each ring of catalyst filled tubes is thus properly heated so as to enhance reforming of the fuel gas reactant.
Abstract:
The fuel cell power plant has a closed water circulation system whose only source of fresh water is the electrochemical reaction in the power section. The water becomes contaminated with ammonia and carbon dioxide in the fuel contact cooler and the ammonia and carbon dioxide are stripped out of the water by steam produced by operating the plant. The ammonia and carbon dioxide-laden steam is vented from the plant. The amount of water lost from the plant as steam is less than the amount of available water produced in the electrochemical reaction.
Abstract:
A fuel gas stream for a fuel cell is humidified by a recirculating hot liquid water stream using the heat of condensation from the humidified stream as the heat to vaporize the liquid water. Humidification is accomplished by directly contacting the liquid water with the dry gas stream in a saturator to evaporate a small portion of the water. The recirculating liquid water is reheated by direct contact with the humidified gas stream in a condenser, wherein water is condensed into the liquid stream. Between the steps of humidifying and condensing water from the gas stream it passes through the fuel cell and additional water, in the form of steam, is added thereto.
Abstract:
Gasifying liquid hydrocarbon fuels, and in particular liquid heavy hydrocarbon fuels, at high fuel-to-air equivalence ratios with no significant soot formation comprises the steps of mixing the fuel and heated air in a prevaporization and mixing zone to prevaporize only a portion of the liquid fuel using only the sensible heat in the air, passing the partially vaporized fuel-air mixture through a catalyst zone to catalytically combust at least some of the prevaporized portion of the fuel while simultaneously, without the use of an external heat source, vaporizing and gasifying as-yet unvaporized fuel using the additional heat generated by the catalytic combustion, wherein the length of the catalyst zone, the catalyst configuration, and the fuel flow rate have been preselected to obtain the desired amount of gasification and to sustain continuous gasification with no significant soot formation.
Abstract:
Compact reaction apparatus, such as apparatus for steam reforming a hydrocarbon feedstock to produce hydrogen, comprises a plurality of tubular reactors vertically disposed and closely packed within a furnace. The furnace is divided into an enhanced heat transfer portion and a burner cavity. Each of the several reactors is disposed partly within the burner cavity and partly within the enhanced heat transfer portion. Heat transfer means, such as particles of a heat transfer packing material, is disposed within the enhanced heat transfer portion of the furnace and is constructed and arranged to provide substantially uniform and enhanced conductive, convective, and radiant heating of that portion of the reactors disposed within the heat transfer portion.
Abstract:
A self-inerting fuel processing system is provided. In one embodiment, the present fuel processing system comprises a fuel processor comprising a reformer, at least one self-reducing catalyst bed, a recycle loop for circulating a gas stream through the fuel processor and the self-reducing catalyst bed(s) during shutdown of the fuel processing system, and an oxidant supply for introducing oxidant into the recycle loop during shutdown of the fuel processing system. A method for shutting down the fuel processing system is provided. A fuel cell electric power generation system incorporating the present fuel processing system is also provided.