6. Recirculation rate and population balance

6.1 Recirculation rate

The recirculation rate, often referred to as the SCR (Solid Circulating Rate), is one of the key factors in CFL operation. This factor only applies to CFLs where the solid phase circulates freely (coal combustion CFLs, for example). The solid phase recirculation flow rate is often much higher than the feed flow rate, and in situ measurement of this flow rate is very difficult, if not impossible, under industrial conditions. However, CFL solids retention varies significantly according to the circulation rate. It is therefore very important to be able to estimate it, even approximately. The recirculation rate (figure 12...