Simulation and experimental study on the effect of iron on the structure and flow properties of coal ash slag

Abstract

Slag fluidity is an important parameter affecting the stable operation of the gasifier. Above liquid temperature, slag fluidity is closely related to its structure. In the present study, the effect of iron on the three-dimensional connection state between [SiO4]4- and [AlO4]5- tetrahedrons in the SiO2-Al2O3-FeO-CaO slag system at 1773 K was deeply discussed by applying molecular dynamics (MD) simulation and ring statistics methods, and the slag network structure was divided into three rings with different functions according to the three-dimensional connection state. It was found that Fe2+ operated as a network modifier ion and substituted Si4+ and Al3+ in the slag and combined with O2–, thereby continuously depolymerizing higher-order rings into lower-order rings. This phenomenon simplified slag structure, reduced internal friction force, and improved fluidity. Finally, the ring distribution coefficient (Rdc) was defined and it was found that there was a linear relationship between Rdc and viscosity.