High density and high solids flux CFB risers for steam gasification of solids fuels

The application of high density and high solids flux CFB risers for steam gasification of solids fuels like coal and biomass has been examined in this paper. A simple mass and energy balance analysis revealed that a steam gasification riser needed to be operated at high solids fluxes in order to supply sufficient heat from the standpipe by circulating hot solids to the endothermic gasification reactor. The important design considerations to achieve high solids circulation rate in the CFB unit were discussed in this paper with emphasis given to the riser height, solids inventory, standpipe to riser diameter ratio, and solids feeding control device.