A fuel cell system includes: a stack generating electric power using reformed gas; a fuel processing device supplying reformed gas; a first gas passage connecting the stack and the fuel processing device, and carrying the reformed gas; a second gas passage connecting the stack and the fuel processing device and carrying an anode off gas (AOG) discharged from the stack; a buffer tank storing the AOG; a first buffer tank passage connecting the buffer tank and the second gas passage; a second buffer tank passage carrying the AOG stored in the buffer tank; a gas mixer connected to the second buffer tank passage and supplying the AOG stored in the buffer tank to the stack; and a controller controlling the gas mixer to supply the anode off gas stored in the buffer tank to the stack so as to preheat the stack or remove air in the stack.

A steam vaporizer assembly includes an internal steam generator having a vessel configured to hold water, a vaporizer unit having a heating element configured to heat the water to generate saturated steam; and a controller configured to: cause the heating element to heat the water to a stand-by temperature; and while maintaining a water level of the water in the vessel between two control points: maintain the water in the vessel at the stand-by temperature until steam generation is required, and when steam generation is required, heating the water in the vessel from the stand-by temperature to a temperature at or above a vaporization temperature of the water using a heating element, to generate the steam.

Fuel cell systems configured for efficient byproduct recovery and reuse are disclosed herein. In one embodiment, a fuel cell system includes a reformer configured to reform a fuel containing methane (CH.sub.4) with steam to produce a reformed fuel having methane (CH.sub.4), carbon monoxide (CO), and hydrogen (H.sub.2). The fuel cell system also includes a fuel cell configured to perform an electrochemical reaction between a first portion of the reformed fuel and oxygen (O.sub.2) to produce electricity and an exhaust having carbon dioxide (CO.sub.2), water (H.sub.2O), and a second portion of the reformed fuel. The fuel cell system further includes an oxygen enricher configured to generate an oxygen enriched gas and a combustion chamber configured to combust the second portion of the reformed fuel with the oxygen enriched gas.

A reformer and an evaporator of a fuel cell module are provided adjacent to each other. An exhaust gas combustion chamber which combusts a fuel exhaust gas and an oxygen-containing exhaust gas discharged from a fuel cell to produce a combustion exhaust gas includes a first chamber and a second chamber connected to each other, and a combustion chamber outlet for discharging the combustion exhaust gas in the exhaust gas combustion chamber. At least part of an outer wall surface of the first chamber faces the evaporator with clearance. At least part of a wall forming the second chamber is a common wall shared with the reformer.

A thermally integrated hotbox apparatus combining a steam reformer, a plurality of solid oxide fuel cell (SOFC) stacks, a plurality of oxidant manifolds, and at least one heat extractor. The steam reformer occupies a central position in the hotbox, around which are disposed in spaced-apart relation a plurality of SOFC stacks. A burner may be associated with the steam reformer, either within or outside the hotbox. An oxidant manifold is disposed between each pair of adjacent SOFC stacks. A heat exchanger is incorporated between an SOFC stack and an oxygen manifold. The hotbox design optimally captures thermal heat from the SOFC stacks for use in producing steam and operating the endothermic steam reformer. The apparatus reduces duty cycle of the burner, which produces heat and steam needed for operation of the endothermic steam reformer.

A method and a device for detecting internal carbon deposition of a solid oxide fuel cell system. The method comprises the following steps: adjusting a temperature in a reformer of the solid oxide fuel cell system so that a mixed gas discharged from the reformer is at a detection temperature; sampling the mixed gas; detecting a gas sample to obtain a mole fraction of each gas, and calculating an equilibrium constant K1 of a Boudouard reaction according to the obtained mole fraction; calculating an equilibrium constant K2 of the Boudouard reaction according to thermodynamics; comparing K1 and K2, if K1 is less than K2, determining that there will be no carbon deposition in the solid oxide fuel cell system; and if K1 is greater than K2, determining that there will be carbon deposition in the solid oxide fuel cell system. By using the method, a carbon deposition condition in the solid oxide fuel cell system can be detected to effect early warning regarding the solid oxide fuel cell system and take preventive measures

A fuel cell system including: an electrochemical pump including a first anode, a first cathode, and a first electrolyte membrane including a proton conductive oxide, the electrochemical pump separating hydrogen from a gas containing the hydrogen, and a solid oxide fuel cell that includes a second anode, a second cathode, and a second electrolyte membrane including a solid oxide electrolyte, and that generates electricity by reacting a fuel gas and an oxidant gas with each other.

A method and a system for the coproduction of hydrogen, electrical power, and heat energy. An exemplary method includes desulfurizing a feed stream to form a desulfurized feed stream, reforming the desulfurized feed stream to form a methane rich gas, and providing the methane rich gas to a membrane separator. A hydrogen stream is produced in a permeate from the membrane separator. A retentate stream from the membrane separator is provided to a solid oxide fuel cell (SOFC). Electrical power is produced in the SOFC from the retentate stream.

A method of operating a solid oxide fuel cell system may comprise contacting a cathode gas comprising oxygen with a heating element to produce a heated cathode gas, passing the heated cathode gas through a cathode of a solid oxide fuel cell stack to increase the temperature of the solid oxide fuel cell stack to an operation temperature and reduce the oxygen to oxygen anions, and passing an anode gas through an anode of the solid oxide fuel cell stack to initiate the electrochemical oxidation of the oxygen anions within the anode. The passing of the anode gas through the anode of the solid oxide fuel cell stack may be initiated when the solid oxide fuel cell stack is heated to an operational temperature.

A fuel cell system that raises temperature of fuel cells by supplying heated air to the fuel cells during starting up period. The fuel cell system includes a plurality of fuel cells, a fuel supply path connected parallelly to the fuel cells to provide fuel thereto, an air supply path connected serially to the fuel cells to provide air thereto, a heat exchanger arranged in the fuel supply path to heat air or fuel, an air heat exchanger arranged in the air supply path to heat air; and a connection path connecting a position of the air supply path upstream to the air heat exchanger with a position of the fuel supply path upstream to the heat exchanger. A first control valve is arranged in the air supply path for controlling the air flowing into to the air heat exchanger. A second control valve arranged in the connection path for controlling the air flowing into the heat exchanger. The fuel cell system controls opening degrees of the first and second control valves during the start-up period of the fuel cell system to supply heated air to the fuel cells through both the air supply path and the fuel supply path.