Step by step methodology of designing a liquid-solid circulating fluidized bed using computational fluid dynamic approach

In this work, a systematic step-by-step methodology has been developed to identify the type of instabilities arise in achieving the continuous solids circulation achieved between riser and downcomer, and in establishing the proper pressure balance among the various units of a liquid-solid circulating fluidized bed (LSCFB) using transient three dimensional computational fluid dynamic (CFD) simulations. Different type of instabilities has been identified and systematically eliminated by choosing the appropriate measure in-terms of the geometry of a LSCFB. This resulted in studying five variant designs of LSCFB studies using CFD. The Eulerian-Eulerian approach is used to simulate the two-phase flow in LSCFB system. The hydrodynamic behavior of the system is studied in terms of the pressure drop, solids holdup at various locations as well as the axial solids hold up distribution. The steady state in the system has been characterized by the solids volume fraction and the pressure balance loop across the closed loop LSCFB. The effect of solids inventory, primary and auxiliary liquid flow, and viscosity of liquid on average solids holdup has been studied with the final LSCFB design.