Numerical simulation of multiphase flow in a full coal-direct chemical looping combustion process

Abstract

Chemical looping combustion (CLC) is a promising clean combustion technology alternative to conventional oxy-combustion, yet the full loop flow details are not well understood. In this work, a multi-fluid model based on the Eulerian-Eulerian framework is used to study the gas-solid hydrodynamics in a full-loop Coal-direct chemical looping (CDCL) combustion unit with a unique moving-bed fuel reactor. The unique fluidization states are described throughout the full-loop system. Then, the influences of several operating conditions on the solid circulation rate and pressure distribution are investigated. It is shown that the solids circulation rate is dominantly controlled by the gas flow rate on the standpipe of the L-valve. Meanwhile, a higher combustor gas velocity reduces the pressure of the whole system and an increased L-valve gas velocity influences the pressure distribution slightly but increases the local pressure at the L-valve. This work provides a cost-effective tool for understanding and optimizing the CDCL process.