Numerical simulation of a 3D full loop iG-CLC system including a two-stage counter-flow moving bed air reactor

Abstract

A three-dimensional two-fluid model is established for an in-situ gasification chemical looping combustion system to predict its dynamic characteristics and non-uniformity in gas-solid distribution. In the experiment, the fuel reactor (FR) and air reactor (AR) were designed as a high-velocity riser and a novel low-velocity moving bed, respectively. Simulations results show that the predicted pressure distributions agree reasonably well with the experimental data. AR operation did not show any obvious influence on oscillations in the full-loop particle circulation. Each stage of the moving bed AR is found to operate better at relatively lower gas fluidizing number, and the maximum allowable fluidizing number is estimated to be around 0.7. With increase in fluidizing number in AR, gas concentration, gas velocity and solid velocity uniformity index increase, while solid concentration uniformity index decreases. Compared to the parallel arrangement of gas distributors and exhausts, gas concentration and velocity uniformity indices are smaller except for the near-exhaust section under the vertical arrangement of gas distributors and exhausts. Increase in first-stage or second-stage AR outlet pressure has an opposite influence on gas leakage in both the first-stage AR and second-stage AR.