Numerical Simulation and Optimization of Slag Bath Coal Gasification Reaction

Abstract

Molten blast furnace slag(BFS) is a huge waste energy in iron and steel industry, the waste heat recovery of the molten BFS has attracted more and more attentions in recent years. A new process for generating hydrogen-enriched syngas by the coal gasification using molten BFS as heat carrier is built, based on this, numerical simulation of coal gasification reaction in the gasifier is carried out with finite rate/eddy dissipation model using ANSYS FLUENT, the distribution of gas components in the molten pool is analyzed and the effect of steam coal ratio(S/C) on the composition of syngas is investigated. At the same time, the coal gasification reaction process is optimized by using matrix analysis method based on orthogonal experiment. Results show that the main gas components in the molten pool are steam, H2, CO and CO2. The steam and CO in the molten pool are mainly distributed outside of the bubble, while H2 and CO2 are mainly distributed in the center of the bubble. Meanwhile, the high S/C ratio will reduce the content of CO in the syngas, which is not conducive to the process of coal gasification. After optimization, the gas holdup in the molten pool increases to 9.429%, the turbulent kinetic energy of molten BFS rises to 12.88x10-3m2/s2, and the splashing rate of molten BFS drops to 2.024. The flow of molten BFS and the mixing degree of gas-liquid phase in the molten pool are enhanced, and the effective composition and calorific value of outlet syngas are also improved.