Extended cyclone theory for gas flows with high solids concentrations

Large recirculation cyclones with high concentrations of particulate solids have gained considerable importance in the field of circulating fluidized bed technology. To calculate a combustion process, the influence of the cyclone on the circulating quantity of solids and their grain size distribution must be known. Measurements in a 105‐MW‐plant in 1989 showed that the existing cyclone theory was not sufficient for this purpose. In a laboratory cyclone (900 mm in diameter), the separation and classification of solids in a gas flow was investigated. The cyclone was fed from a fluidized bed and operated with cold air and quartz of various grain size distributions. Based on this experimental device and the theory of momentum transfer between solids and gas flow, a new, more accurate method of calculating the separation efficiency was developed.