Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuels

Introduction In recent years more concerns have arisen about CO2 emission due to global warming. Among available or proposed technologies, chemical looping combustion (CLC) is the most promising technology to combine fuel combustion and CO2 purification. It uses a solid oxygen carrier to transfer the oxygen from the air to fuel in a reducer and oxidizer. Thus, air is never mixed with the fuel, and the CO2 does not become diluted by the nitrogen of the flue gas. NOx formation can be largely eliminated. A number of metals have been discussed in the literature, such as oxides of Fe, Ni, Co, Cu, Mn. Solid fuels such as coal and biomass have been ignored in CLC process due to technical problems, including the separation of oxygen carrier from fuel and ash, the possible interaction between the fuel ash and oxygen carriers and the combustion of unburned carbon particles in the oxidizer due to the circulation of solid fuel particles. The adaptation of the CLC to the combustion of solid fuels presents many challenges. In this paper, an innovative concept – application of a CFB combined with a moving bed on the chemical looping combustion of solid fuels is introduced.