Three-Dimensional Simulation for an Entrained Flow Coal Slurry Gasifier

Abstract

A comprehensive three-dimensional (3D) numerical model is developed for simulation of entrained coal slurry gasifiers. In this model, a presumed probability density function (PDF) method is used to consider turbulent effects on gas-phase reactions in the gasifier. A realizable k−ε model is adopted to predict turbulence information. Coal slurry particles are tracked with the Lagrangian method. The coal slurry gasification process is divided into several simple subprocesses, which are droplet evaporation, boiling, devolatilization, and heterogeneous reactions of coal char particles. The particle-source-in-cell method is adopted to couple gas−particle interactions. With this methodology, simulations for GE and staged coal slurry gasifiers are completed. A comparison between the predictions and measured data shows that the proposed model correctly predicts the global performance of the coal gasification process. The mixing process in the staged gasifier is better than that in the GE gasifier because of the existence of secondary flow. The particle size has a negative effect on coal conversion. The effects of the coal slurry concentration and molar ratio of oxygen/carbon on the gasifier performance are also studied in this paper.