A new CO2 absorption fluidized bed reactor is presented for a continuous CO2 capture process using sodium- or potassium-based solid sorbents. The absorption reactor includes a bubbling bed and a narrowed upper riser, which are connected by using a combination of a central tube and a draft tube. The control of solid circulation is demonstrated by a cold model. Effects on the solid circulation rate (G(s)) of various parameters are investigated, including the geometry parameters (the position of the central tube exit, and the draft tube diameter), the operating parameters (gas velocity in the draft tube and the annular zone, the static bed material height, and the particle size). Finally, an expression is derived to correlate G(s) as a function of the particle properties and operating conditions.