Chemical-Looping Technologies using Circulating Fluidized Bed Systems: Status of Development

In chemical-looping combustion (CLC), an oxygen carrier provides lattice oxygen for complete combustion of a fuel for heat and power production. The reduced metal oxide is then oxidized in a separate reactor. The combustion products CO2 and H2O are obtained in pure form, without any nitrogen in the gas. As no gas separation work is needed, this could be a breakthrough technology for carbon capture (CCS). Normally, the fuel- and air-reactor are designed utilizing inter-connected fluidized beds. The same underlying reversible redox reactions of CLC can be used for other fuel conversion technologies. These include fluidized bed processes for gas, solid and liquid fuels for heat, power, syngas or hydrogen production. Some of these concepts were suggested as far back as the 1950’s, while others have just recently been proposed. Chalmers University of Technology has been involved in CLC research for over 18 years, and this paper will provide a review of some recent developments with respect to CLC with gaseous, liquid and solid fuels. Further, the paper will provide an overview some related technologies where Chalmers is conducting research: i) Chemical-looping gasification (CLG), ii) Chemical-looping reforming (CLR) and iii) Chemical-looping tar reforming (CLTR). In these processes, a pure syngas/hydrogen can be produced effectively, which could be utilized for chemical or fuel production