Simulation of entrained flow gasification with advanced coal conversion submodels. Part 2: Char conversion

CFD modeling results for entrained flow coal gasification using advanced submodels for coal conversion are presented and compared to detailed experimental data. The focus of this investigation is on the accurate modeling of the char conversion process. The CBK/E and CBK/G models are used for calibrating a simplified Single Nth-Order Reaction (SNOR) kinetic model, which is suitable for CFD calculations. The kinetics of the CBK/G model are fitted using char gasification data obtained from drop tube furnace experiments. CFD simulations are performed for the BYU entrained flow gasifier fired with four different coals varying significantly in rank ranging from bituminous coal to lignite. The comparison with the experiments generally gives good agreement in terms of flame stand-off, gas composition and carbon conversion when the kinetics of the CBK/G model calibrated with drop tube experiments is used. On the other hand, lower carbon conversion is obtained using the default correlation of the CBK/G model, which only allows to depict the overall tendency of the gasification reactivity with coal rank.