Applications of chemical-looping combustion with capture of CO2

Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO2. The technique involves the use of a metal oxide as an oxygen carrier which transfers oxygen from the combustion air to the fuel. Hence the direct contact between fuel and combustion air is avoided. Subsequently, the products from combustion, e.g. carbon dioxide and water, will be kept separate from the rest of the flue gases, e.g. nitrogen and any remaining oxygen. Two reactors in the form of interconnected fluidized beds are used in the process: i) a fuel reactor where the metal oxide is reduced by reaction with the fuel, and ii) an air reactor where the reduced metal oxide from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO2 and H2O, while the outlet gas stream from the air reactor contains only N2 and some unused O2. The net chemical reaction over the two reactors is the same as for normal combustion with the same amount of heat released, but with the important difference that carbon dioxide is inherently separated from nitrogen, and no extra energy is needed for this separation. This is in contrast to known techniques for separating carbon dioxide from flue gas, where large amounts of energy an