A comprehensive hydrodynamic study of a Liquid -Solid Circulating Fluidized Bed (LSCFB) is conducted with changes in viscosity of the fluidizing medium and the inventory height of solids initially fed into the system. An LSCFB of height 2.95m and riser outer diameter 0.1m was chosen for experimentation. The three liquid media systems with varying viscosities that were chosen were water, glycerol 10% (v/v) and glycerol 20% (v/v). Effect of inventory on the hydrodynamics was also studied, by taking initial heights of inventory to be 15cm, 25cm and 35cm. The hydrodynamic studies concentrated on pressure gradients along the axial pressure tapings, axial solid holdup, average solid holdup, solid circulation rate and slip velocity. Uniformity in axial solid holdup and average solid holdup was validated for changes in viscosity and inventory. Solid flux was seen to follow an inverse relationship to holdup. The changes in slip velocity with varying viscosity and inventory were studied, and found to decrease with both variables. The distribution parameter, Co of the drift flux model was found to be in the range of 0.983-0.994, suggesting non-uniformity in radial solid distribution, with higher solid concentration by the walls compared to the core of the column.

Circulating fluidized beds (CFB) play a major role in the chemical industry especially as heterogeneous catalytic reactors. Research on hydrodynamic properties of Liquid – Solid CFBs (LSCFB) is significantly under-reported as compared to Gas – Solid CFBs (GSCFB). Steadily, prominent research is being established in fields like food industry (whey protein recovery), waste management (removal of heavy metals from radioactive wastes) and others, which use LSCFBs. In this context, it is important to have significant knowledge about the changes occurring in hydrodynamic properties like solid hold-up, rate of solid circulation etc., on changing certain critical physical properties such as inventory height. An LSCFB of height 2.95 m and riser outer diameter 0.1 m was chosen and the effect of inventory height on the properties was studied by taking the initial inventory heights as 15 cm, 25 cm and 35 cm. The hydrodynamic studies concentrated on axial solid holdup, average solid holdup, solid circulation rate and slip velocity. On increasing the inventory, uniformity of axial solid holdup was confirmed along with studying holdup patterns. Solid flux was seen to follow an inverse relationship to holdup, as expected. The change in slip velocity with varying inventory was also checked, and was found to decrease with inventory. The distribution parameter, Coof the drift flux model was used to determine the extent of non-uniformity in solid distribution. Cowas calculated to be less than unity in the range of 0.983–0.994, suggesting non-uniformity in solid distribution, with higher solid concentration by the walls compared to the core.