STUDY OF RISER GEOMETRIES AND EXIT EFFECT ON HYDRODYNAMICS OF THE RISER OF CIRCULATING FLUIDIZED BED USING CFD SIMULATION

Abstract

Circulating fluidized bed (CFB) risers with Geldart A and Geldart B particles find significant application in Fluid catalytic cracking (FCC) and combustion reactions respectively. CFB have found applications in many important industries, and contributions the hydrodynamics of the gas-solid flows in riser systems can significantly enhance the efficiency and productivity of such processes. Gas—solid separation, for instance, is one of the most important and difficult tasks in circulating systems affecting the exit region hydrodynamic structure and solid residence time. The present work attempts to study the solids flow dynamics in a CFB riser operated with Group A and Group B particles using computational fluid dynamics (CFD) techniques. In this work, the different designs of riser geometries exits were studied using a 2D transient Eulerian approach with kinetic theory of granular flow in a commercial CFD simulation package. The three exits namely typical riser, curve riser and inside riser were designed and simulated. The various factors like solid volume fraction, pressure drop, solid velocity was studied for both Group A and Group B particles.