Solid circulation and loop-seal characteristics of a dual circulating fluidized bed: Experiments and CFD simulation

A dual circulating fluidized bed reactor (riser: 0.04 m × 0.11 m × 4.5 m high; bubbling fluidized bed: 0.285 m × 0.11 m × 2.13 m high) was designed and constructed to investigate hydrodynamics on dual fluidized bed gasifier (DFBG) and chemical looping combustion (CLC). Effects of gas velocities to a riser, bubbling fluidized bed, supply chamber, and recycle chamber as well as vertical aeration rate on solid circulation rate and solids flow characteristics in a loop-seal were determined experimentally. Hydrodynamic characteristics were identified by computational fluid dynamics (CFD) simulation where a two-dimensional (2D) multiphase Eulerian model incorporating with the kinetic theory of solid particles was used.The solid circulation rate increases with increasing gas velocity into the loop-seal and the riser. At the same vertical aeration rate, the maximum solid circulation rate was obtained at a loop-seal height/base line (h/l) ratio of 2.5. When the supply chamber was connected to a bubbling fluidized bed, the pressure drop of the loop-seal was found to be affected by fluidizing state of the bubbling fluidized bed.