A method for estimating a hydrogen concentration of a fuel cell includes estimating an initial amount of gas included at an anode side of a fuel cell, calculating a crossed over amount of gas between the anode side and a cathode side of the fuel cell and an amount of gas purged from the anode side to the outside from time when an initial amount of gas is predicted to a present time, and estimating a current hydrogen concentration at the anode side based on the predicted initial amount of gas, the calculated amount of crossed over gas, and the amount of purged gas.

A fuel cell includes a cathode side and an anode side. An oxidant gas is fed to the cathode side. In the cathode side, an oxidant exhaust gas is generated by using the oxidant gas. A fuel gas is fed to the anode side. In the anode side, a fuel exhaust gas is generated by using the fuel gas. The oxidant exhaust gas and the fuel exhaust gas are discharged from an outlet of a mixed exhaust gas discharge pipe as a mixed exhaust gas. The dilution apparatus is connected to the outlet of the mixed exhaust gas discharge pipe. The dilution apparatus includes a stirring chamber and an opening. The stirring chamber communicates with the mixed exhaust gas discharge pipe and expands from the outlet of the mixed exhaust gas discharge pipe. The opening is provided in the stirring chamber to take in air.

A fuel cell system includes a fuel cell stack having a plurality of fuel cells that each contain a plurality of fuel electrodes and air electrodes. The system includes a fuel receiving unit connected to the fuel cell stack, which receives a hydrocarbon fuel from a fuel supply. The system includes a fuel exhaust processing unit fluidly coupled to the fuel cell stack by a slip stream, where the fuel exhaust processing unit processes fuel exhaust from the fuel cell stack, and the slip stream is fluidly connected to an exhaust stream flowing from the fuel cell stack. The fuel processing unit removes a first portion of carbon dioxide (CO.sub.2) from fuel exhaust within the slip stream, outputs the first portion of CO.sub.2 in a first stream, and outputs a second portion of CO.sub.2 remaining from the fuel exhaust in the slip stream into a second stream, which includes hydrogen.

A solid particulate capturing device comprises a first plate (2) having at least one inlet section (6) for an exhaust gas flow, a second plate (3), parallel to the first (2), having at least one outlet section (7) for the exhaust gas flow. The first (2) and the second plate (3) are axially spaced apart and form, with an annular lateral wall (4), interposed between the first (2) and the second plate (3), an entrapment chamber (5) for solid particulate conveyed in suspension in the exhaust gas flow produced by a battery. The outlet section (7) present on the second plate (3) is axially out of alignment with the inlet section (6) present on the first plate (2), in such a way that the inlet section (6) faces a solid portion (8) of the second plate (3) which acts as an obstructing surface for the solid particulate.

The invention relates to a method for switching off a fuel cell system (100) having a fuel cell stack (10), that has anode chambers (13) and cathode chambers (12), and a cathode supply (20) having a cathode supply path (21) for supplying an oxygenated cathode operating gas into the cathode chambers (12), a compressor (23) arranged in the cathode supply path (21) and a cathode exhaust path (22) for discharging a cathode exhaust gas from the cathode chambers (12). The method comprises the steps of: (a) Maintenance of the cathode chambers (12) under excess pressure while preventing a flow of cathode operating gas through the cathode chambers (12) while keeping the cathode operating gas that is present in the cathode chambers (12) oxygen-depleted; (b) Expansion of the oxygen-depleted cathode operating gas present in the cathode chambers (12) via the cathode supply path (31) [sic] and/or the cathode exhaust path (22), and (c) Separation of the cathode chambers (12) from the environment.

A fuel cell device is improved for operating conditions during a partial load operation. The fuel cell device comprises a cell stack formed by electrically connecting fuel cells for generating power by fuel gas and oxygen-containing gas; a fuel gas supply unit for supplying the fuel gas to the fuel cells; and a power adjustment unit for adjusting the amount of current that is supplied to an external load and a controller for controlling the fuel gas supply unit and the power adjustment unit. The controller adjusts, during the partial load operation of the fuel cell device and when the fuel gas supplied to the cell stack is at a low flow rate. The relationship between a fuel utilization rate of the cell stack and the amount of power generated by the cell stack can be nonlinear.

A fuel cell device is improved for operating conditions during a partial load operation. The fuel cell device comprises a cell stack formed by electrically connecting fuel cells for generating power by fuel gas and oxygen-containing gas; a fuel gas supply unit for supplying the fuel gas to the fuel cells; and a power adjustment unit for adjusting the amount of current that is supplied to an external load and a controller for controlling the fuel gas supply unit and the power adjustment unit. The controller adjusts, during the partial load operation of the fuel cell device and when the fuel gas supplied to the cell stack is at low flow rate. The a relationship between a fuel utilization rate of the cell stack and the amount of power generated by the cell stack can be nonlinear.

A redox flow battery includes a cell in which a first chamber in which a first electrode serving as an anode during charging is installed and a second chamber in which a second electrode serving as a cathode during charging is installed are divided by a membrane, a first tank that stores a first electrolyte, a first circulation device including a first supply path that connects the first tank and the first chamber and a first recovery path that connects the first chamber and the first tank, a second tank that stores a second electrolyte, a second circulation device including a second supply path that connects the second tank and the second chamber and a second recovery path that connects the second chamber and the second tank, and an adjustment path that supplies gas included in the first tank to the second recovery path.

Disclosed are a fuel cell system capable of maintaining hydrogen density of the exhaust gas discharged from the fuel cell system at a level below the tolerance limit so that any fears about fire and/or explosion can be dispelled and the safety of the system can be remarkably improved, and a humidifier therefor. The fuel cell system of the present invention comprises a fuel cell stack; and a humidifier configured to (i) humidify an air supplied from outside by means of an off-gas discharged from the fuel cell stack and (ii) supply the humidified air to the fuel cell stack, wherein the off-gas is mixed with at least a portion of the humidified air in the humidifier.

In various aspects, systems and methods are provided for operating molten carbonate fuel cells with processes for iron and/or steel production. The systems and methods can provide process improvements such as increased efficiency, reduction of carbon emissions per ton of product produced, or simplified capture of the carbon emissions as an integrated part of the system. The number of separate processes and the complexity of the overall production system can be reduced while providing flexibility in fuel feed stock and the various chemical, heat, and electrical outputs needed to power the processes.