Numerical simulations of coal gasification in 15MW_th KEDA® circulating fluidized bed: Influences of high-temperature preheating

Fluidized bed gasification is widely used to thermochemically convert coal to syngas and high-temperature preheating is usually employed to enhance gasification performances. However, owing to the experimental difficulties, influences of high-temperature preheating, as well as details of the corresponding reactive flow, have not been quantified in the industrial-scale gasifier. In this work, a 15MW_th KEDA® circulating fluidized bed (KEDA®CFB) coal gasifier was simulated with a two-dimensional (2D) reactive multiphase particle-in-cell (MP-PIC) model, and the pyrolysis kinetics were developed with volatile cracking experiments. Predictions agree well with the industrial data in terms of gas components and bed temperatures. The influences of preheating temperature were studied from perspectives of flow hydrodynamics, thermochemical characteristics, species distributions, higher heating value (HHV), and cold gas efficiency (CGE). It has been found that the preheating temperature has direct and significant impacts on gasification efficiency. An increase in preheating temperature from 400 K to 1300 K leads to a significant increase in HHV (5.55–6.28 MJ/Nm³) and CGE (61–74.7 %). The simulations offer guidelines for technological economy analysis and could serve for the optimization of gasifier structure.