Numerical analysis of gasification performance via finite-rate model in a cross-type two-stage gasifier

The gasification process of a pressurized, oxygen-blown, entrained-flow E-Gas like gasifier through numerical modeling is investigated by solving the 3-D, steady-state Navier-Stokes equations with the Eulerian-Lagrangian method. Eight chemical reactions are solved via the Finite-Rate/Eddy-Dissipation Model. The preliminary gasification process is successfully modeled and the global chemical reactions are proved to be strongly affected by the finite rates. The results of parametric study show that the increasing O2/Coal ratio results in a decrease of CO, but an increase of CO2 and exit temperature. With a modified water-gas-shift reaction rate, a more reasonable trend is obtained that as the coal slurry concentration decreases, the mass flow rate of H2, CO2, and H2O increase while that of CO decreases. As the amount of coal slurry mass flow in the first stage increases, the exit temperature and the mole fraction of H2 and CO2 increase, while that of CO decreases. However, different fuel distributions do not provide notable influence on gasification performance due to the large space inside the E-Gas gasifier allowing complete reaction. The overall results show that the present CFD model can adequately capture the gasification behavior and analyze gasification performance inside the gasifier.