No abstract

Chemical-looping combustion (CLC) is a combustion method for a gaseous fuel with inherent separation of the greenhouse gas carbon dioxide. A CLC system consists of two reactors, an air reactor and a fuel reactor, and an oxygen carrier circulating between the two reactors. The oxygen carrier transfers the oxygen from the air to the fuel. The flue gas from the fuel reactor consists of carbon dioxide and water, while the flue gas from the air reactor is nitrogen from the air. A two-compartment fluidized bed CLC system was designed and tested using a flow model in order to find critical design parameters. Gas velocities and slot design were varied, and the solids circulation rate and gas leakage between the reactors were measured. The solids circulation rate was found to be sufficient. The gas leakage was somewhat high but could be reduced by altering the slot design. Finally, a hot laboratory CLC system is presented with an advanced design for the slot and also with the possibility for inert gas addition into the downcomer for solids flow increase.

No abstract

Chemical-looping combustion (CLC) is a novel combustion technology with inherent separation of the greenhouse gas CO2. The technique involves the combustion of gaseous fuel using a metal oxide for oxygen transfer. The system consists of two reactors, a fuel reactor and an air reactor, and an oxygen carrier in the form of a metal oxide that transports oxygen from the air to the fuel. Direct contact between fuel and combustion air is avoided, and the products from combustion are kept separated from the rest of the flue gases. A dual-fluidized bed reactor system representing a 10-kW CLC prototype was designed. A scaled flow model was built and investigated. Gas velocities and designs were varied, while solids circulation rate and gas leakage between the reactors as well as static pressure balance and residence time distribution of gas and particles were measured. Results show that the solids circulation rates were sufficient and the gas leakage could be decreased to very low values.