Characterization of high-turbulence zone in slowly moving bed slagging coal gasifier by a 3D mathematical model

Abstract

A slowly-moving bed slagging coal gasifier (SMB gasifier) is developed for utilizing those largely-reserved coals with high ash fusion temperature (>1500°C). Mathematical modelling is regarded more effective than experimental studies to understand and optimize the performance of the gasifier at industry scale. In this paper, a three-dimensional (3D) computational fluid dynamics (CFD)-based mathematical model has been developed to study the shape and size of the so-called high-turbulence zone in the SMB slagging coal gasifier. Reynolds number and volume fraction of solid phase are used to define the boundary of high-turbulence zone, with their critical values 250 and 0.6, respectively. The influences of gasifying agent velocity and coal particle size on the shape and size of the high-turbulence zone are also investigated. The simulation results indicate that with the increase of coal particle size and gasifying agent velocity, the shape of high-turbulence zone is changed from boot-shape to arch-shape, and the slugging in the upper part of the gasifier is confirmed.