Experimental and numerical study on multiphase fluid dynamics of coal and blends with biomass (sugarcane bagasse) in a lab-scale full-loop circulating fluidized bed gasifier

The current research presents a 3-D hydrodynamic simulation of the fluidized bed riser with a validated CFD model at different superficial gas velocities and inventory composition (coal of 2 kg is blended with sugarcane bagasse weights 0.2 kg and 0.8 kg). The experiments are performed by varying superficial gas velocity (0.5 Umf to 3 Umf), coal particle size (460 mu m and 460 mu m), and coal bed inventory size (1.5 kg and 2 kg) in a pilot-scale circulating fluidized bed riser of 100 mm diameter and 3000 mm height. The CFD model results are in good agreement with experimental pressure drop and solid volume fraction. The effect of drag and lift force in fluidization hydrodynamics has been studied. The validated CFD model is then extended to predict the hydrodynamics of the three-fluid, coal-sugarcane bagasse-air system. A mixing factor is defined to quantify the mixing behavior of coal and sugarcane bagasse. It is concluded that a 200 gm sugarcane bagasse blend has good mixing than the 800 gm blends. For efficient mixing, coal and sugarcane bagasse fluidized beds should operate in the 2 Umf to 4 Umf superficial gas velocity range. The results of axial and radial distribution of coal, sugarcane bagasse and air volume fraction, pressure drop, slip velocity, and fluidized bed heights are presented.