A transient method to study the pressure drop characteristics of the cyclone in a CFB system

A transient method was developed and applied to study the variation of pressure drop characteristics of the cyclone ΔPc used in a circulating fluidized bed (CFB) system with the solid concentration at the inlet Cs,in. Experiments were conducted in a CFB apparatus, with a square riser of 0.1 m × 0.1 m in cross-section and 3.2 m in height, and with a smooth riser exit. When the system was in a steady state with a large Cs,in, the supply of solid material to the riser was suddenly cut-off while the gas velocity was maintained at a constant. Cs,in was derived by the pressure drop measured across the smooth riser exit. ΔPc and Cs,in were measured on-line during the transient process. Experimental results showed that ΔPc and Cs,in obtained by the transient method were in good agreement with those obtained by the steady state experiments. Furthermore, ΔPc decreased at first with increasing Cs,in and then reached at a minimum at the critical Cs,in, thereafter it increased with Cs,in. The transient method offers an acceptable accurate, cost-effective and productive means to study the ΔPc over a wide range of Cs,in.