Gasification of coal and biomass is in pursuit of the technologies based on dual bed combination and a high-density transport bed. Dual fluidized bed gasification (DFBG) relies on rapidly circulated particles between its combustor and gasifier to provide the endothermic heat required by the gasification. High-density transport bed gasification (HTBG) has to work with a high solid flux and a high particle density inside its gasifier so as to increase the heat reserve in the bed and to suppress tar evolution there. The idea of coupling a moving bed to the bottom section of the riser of a circulating fluidized bed (CFB) was proposed to realize the desired high solid-flux conveying flow inside the riser. Experiments in a 12-m high and 90 mm i.d. riser of the newly configured CFB demonstrated that at superficial gas velocities of about 9.6 m/s, a solid circulation rate as high as 370 kg/(m(2) s) and all average solid holdup of about 0.12 in the bottom section of the riser were readily achieved simultaneously for the silica sand particles of 378 mu m in Sauter mean diameter. Parametric investigation further clarified that the solid circulation rate and the local solid holdup at the riser bottom of the newly configured CFB were highly dependent on the moving bed aeration and the primary gas velocity of the riser, whereas changing the solid inventory in the system did not greatly affect those two variables. Adoption of a secondary air injection into the riser enabled adjustment of the solid circulation rate within a certain range, showing essentially a complementary rneans for controlling the gas-solid flow inside the riser of the newly configured CFB.