Interfacial area and liquid-side and overall mass transfer coefficients in a three-phase circulating fluidized bed

The characteristics of the gas–liquid interfacial area (a) and the true liquid-side (kL) and volumetric (kLa) mass transfer coefficients were investigated in the riser of a three-phase circulating fluidized bed (TPCFB). The values of kLa and a were determined from the simultaneous physical desorption of O2 and chemical absorption of CO2 into the liquid phase. The effects of the gas (UG: 0.02–0.08 m/s) and liquid (UL: 0.24–0.32 m/s) velocities, particle size (dP: 0.5–3.0×10−3 m) and solid circulation rate (GS: 2.0–8.0 kg/m2s) on the values of kLa, a and kL were examined. The values of kLa and a increased with increasing gas velocity, particle size and solid circulation rate but increased only slightly with increasing liquid velocity in the riser. The true liquid-side mass transfer coefficient increased with increasing gas and liquid velocities, particle size and solid circulation rate. The values of kLa, a and kL were well-correlated in terms of the operating variables such as gas and liquid velocities, particle size and solid circulation rate.

► Interfacial area in the TPCFB (three-phase circulating fluidized bed) was measured for the first time. ► Liquid side mass transfer coefficient in the TPCFB was measured for the first time. ► Effects of liquid velocity on the interfacial area and mass transfer in the TPCFB were determined. ► Effects of solid circulation rate on the interfacial area and mass transfer in the TPCFB were determined.