Method and system for producing direct reduced metal material, comprising the steps: a) charging metal material to be reduced into a furnace space (120); b) evacuating an existing atmosphere from the furnace space to achieve a gas pressure of less than 1 bar therein, c) providing heat and hydrogen gas into the furnace space, so that heated hydrogen gas heats the charged metal material to a temperature high enough so that metal oxides present in the metal material are reduced, in turn causing water vapour to be formed, which hydrogen gas provision is performed so that a pressure of more than 1 bar builds up inside the furnace space; and d) before evacuating the built up overpressure, condensing and collecting the water vapour formed in step c in a condenser (160) below the charged metal material. The invention is characterised in that it further comprises the step e) before evacuating the build up overpressure, providing a carbon-containing gas to the furnace space, so that the heated and reduced metal material is carburized by said carbon-containing gas.

In various aspects, systems and methods are provided for integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process. The molten carbonate fuel cells can be integrated with a Fischer-Tropsch synthesis process in various manners, including providing synthesis gas for use in producing hydrocarbonaceous carbons. Additionally, integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process can facilitate further processing of vent streams or secondary product streams generated during the synthesis process.

In various aspects, systems and methods are provided for integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process. The molten carbonate fuel cells can be integrated with a Fischer-Tropsch synthesis process in various manners, including providing synthesis gas for use in producing hydrocarbonaceous carbons. Additionally, integration of molten carbonate fuel cells with a Fischer-Tropsch synthesis process can facilitate further processing of vent streams or secondary product streams generated during the synthesis process.

A blast furnace system is used wherein the coke rate is decreased by recycling upgraded top gas from the furnace back into its shaft section (which upgraded top gas is heated in a tubular heater prior to being recycled). The top gas, comprising CO, CO.sub.2 and H.sub.2, is withdrawn from the upper part of the blast furnace; cooled and cleaned of dust, water, and CO.sub.2 for increasing its reduction potential and is heated to a temperature above 850 C. before being recycled thus defining a first gas flow path used during normal operation of the blast furnace. Uniquely, a second gas flow path for continued circulation of top gas selectively through the heater and a cooler during operation interruptions of the blast furnace allows time for gradual controlled cool down of the heater in a manner to avoid heat-shock damage to the tubular heater.

A thermally efficiency regenerative air preheater 250 extracts more thermal energy from the flue gas exiting a solid fuel fired furnace 26 by employing an alkaline injection system 276. This mitigates acid fouling by selectively injecting different sized alkaline particles 275 into the air preheater 250. Small particles provide nucleation sites for condensation and neutralization of acid vapors. Large particles are injected to contact and selectively adhere to the heat exchange elements 542 and neutralize liquid acid that condenses there. When the deposit accumulation exceeds a threshold, the apparatus generates and utilizes a higher relative percentage of large particles. Similarly, a larger relative percentage of small particles are used in other cases. Mitigation of the fouling conditions permits the redesign of the air preheater 250 to achieve the transfer of more heat from the flue resulting in a lower flue gas outlet temperature without excessive fouling.

Methods and systems for producing direct reduced iron having increased carbon content, comprising: providing a reformed gas stream from a reformer; delivering the reformed gas stream to a carbon monoxide recovery unit to form a carbon monoxide-rich gas stream and a hydrogen-rich gas stream; and delivering the carbon-monoxide-rich gas stream to a direct reduction furnace and exposing partially or completely reduced iron oxide to the carbon monoxide-rich gas stream to increase the carbon content of resulting direct reduced iron. The carbon monoxide-rich gas stream is delivered to one of a transition zone and a cooling zone of the direct reduction furnace. Optionally, the method further comprises mixing the carbon monoxide-rich gas stream with a hydrocarbon-rich gas stream.

In a method and a device for operating a smelting reduction process, at least part of an export gas from a blast furnace or a reduction unit is thermally utilized in a gas turbine and the exhaust gas of this gas turbine is used in a waste heat steam generator to generate steam. The remaining part of the export gas is fed to a CO.sub.2 separation apparatus, the tail gas thereby obtained being fed to a waste heat steam generator and burned for additional steam generation. The combustible components of the tail gas are sent for thermal utilization in a steam generator, so that the overall energy balance of the thermal use of the export gas is improved. In addition, a further part of the export gas is qualitatively improved by the CO.sub.2 separation apparatus, so as to generate a high-quality reduction gas which can be supplied for metallurgical use.

In various aspects, a method for producing electricity by operating two or more turbines in series is provided. The method can include introducing, at least part of, the exhaust from an upstream turbine into a combustion chamber of a downstream turbine. In one aspect, exhaust from the upstream turbine is introduced into the downstream turbine's combustion chamber via the downstream turbine's compression chamber.

A method of starting a molten-bath based melting process includes commencing supplying cold oxygen-containing gas and cold carbonaceous material into a main chamber of a smelting vessel within at most 3 hours after completing a hot metal charge into the vessel and igniting the carbonaceous material and heating the main chamber and molten metal in the main chamber.

Systems and methods are provided for capturing CO.sub.2 from a combustion source using molten carbonate fuel cells (MCFCs). At least a portion of the anode exhaust can be recycled for use as part of anode input stream. This can allow for a reduction in the amount of fuel cell area required for separating CO.sub.2 from the combustion source exhaust and/or modifications in how the fuel cells can be operated.