A mathematical model predicting particles flux ratio between internal circulation and external circulation processed in a coupled reactor with gas-solids loop fluidized bed was established.In a wide range of operating conditions

particles circulation flux ratio was predicted

and the particles circulation ratio np=20 was determined as a criterion to analyze the particles mixing behavior in internal and external loops.The results showed that the calculated values basically agreed with experimental data

and the average relative error approached 15.35%.Particles circulation ratio increased with increasing superficial gas velocity in the draft tube

however decreased with increasing particles external circulation flux and opening rate of a lotus-shaped distributor

with the change in two stages

first fast and then slow.The transition points were Ug

d=0.50 m·s-1

Gs

r=110 kg·m-2·s-1

and α=10% respectively.Under the operating conditions of riser superficial gas velocity Ug

r=10—21.17 m·s-1

draft tube superficial gas velocity Ug

d=0.57—1.50 m·s-1

particles external circulation flux Gs

r ≥110 kg·m-2·s-1

and distributor open rate α≥10%

the particles complete mixing status in the riser and the gas-solids loop bed reactor could be avoided.