Effect of specularity co-efficient on bed hydrodynamics and heat transfer characteristics of a PCFB riser

Abstract

Abstract The fluidized bed gasification and combustion process are getting attention from researchers due to its advantages such as low NOx emission and power production from waste materials. Laboratory scale study of fluidized bed gasifier and combustor is not possible due to its high instalment cost. The heat supply and temperature are also of higher magnitude. A simulation study of large-scale fluidized bed setup is a potential solution to such a problem. Hence this numerical study directs the multiphase simulation of 3D fluidized bed riser using ANSYS Fluent. The riser of 2000 mm in height and 54 mm of outer diameter is considered for numerical simulation. Air with a superficial velocity of 6 m/s and sand with 2300 kg/m3 and a mean particle size of 307 μm are considered as primary and secondary phase material for the numerical simulation. The effect of the specularity co-efficient volume fraction of air has been calculated numerically. Along with the riser height, the temperature contour indicates the distribution of temperature. When the air pressure at the inlet of the riser rises, the volume fraction of air is found to be declining. The solid mass flux increases with pressure at all values of the specularity coefficient. The maximum suspension density is found to be 892 kg/m3 for the operating pressure of 5 bar. The maximum solid mass flux is observed at 5 bar pressure for this simulation work.