Extensive research on air loop reactors (ALR) has been conducted

but mostly limited to gas-liquid and gas-liquid-solid systems.Work associated with gas-solid systems has been rare and mainly focused on draft tube-lifted fluidized bed and spouted bed.The present paper addressed a gas-solid air-loop reactor treating fine Geldart A particles and operating in a new annulus-lifted mode

with bubbling or turbulent bed upward flow in the annulus in parallel with bubbling bed downward flow in the draft tube.The influence of operating conditions and axial position of draft tube gas distributor on the distribution of bed density

particle circulation velocity and circulation mass flowrate is discussed.By mounting draft tube gas distributor in the bottom region

bed density radial distribution and particle circulation mass flowrate is significantly improved.Bed density in 0.367 <r/R<0.49 is still high

signifying a limited influence range and potential optimization of gas distributor.Particle circulation velocity and circulation mass flowrate for the axial position of 32 mm is greater than that for other axial positions.