The inlet necking angle has an important influence on flow field and separation performance of cyclone separator

thus affecting the operation performance of circulating fluidized bed(CFB) units. By taking the cyclone separator equipment of Linqingsanhe 280 t/h full-scale CFB boiler as the example

the numerical simulation of five cyclone separators with inlet necking angle of 14°

20°

25°

30° and 34° is carried out. The results show that

with a constant flue gas flow and as the inlet necking angle is increased

the tangential velocity and the centrifugal force on the particles increase

the downstream velocity of axial velocity increases while the upstream velocity decreases

the pressure drop of the cyclone separator rises while the separation efficiency increases at first and then decreases. The effect of the necking angle and necking velocity on the separation efficiency is further studied

and it shows that there are optimum values for both necking angle and necking velocity. Within the scope of this study

the optimum values of the necking angle and necking velocity of the cyclone separator are 30° and 20 m/s

respectively.