Numerical Simulation Approaches for Modelling a Single Coal Particle Combustion and Gasification

摘要

Combustion and gasification are the fundamentalprocesses of coal utilization, and the research of theseapplications has been continuously progressing. Numericalmodelling is one of the methodologies that also has significantadvancement, due to the progress of computational engineeringand also considering economic impact. This paper is a part ofthe numerical developments on the coal combustion andgasification that introduces a new approach by which a singlecoal particle model has been developed and used to investigatethose processes. CFD (Computational Fluid Dynamics)techniques with an Eddy Break Up (EBU) model and also witha set of kinetics parameter reactions are used in the study.However, defining the chemical reactions is crucial for themodel development. Seven reactions for coal combustion andadditional six reactions for gasification are investigated. It isidentified that the best fit kinetic parameter value for the pre-exponent factor (A) of R2 and R3 , while comparing with theexperimental results, is 20 and 1000, respectively. Finally, thesevalues are implemented into the model of both coal particlecombustion and gasification for investigation. The results of thesimulation show that the H 2 and CH 4 products from thegasification are significantly higher than those from thecombustion. The maximum mole fraction value of CO productsin combustion is ~ 1.5 times higher than in gasification at an aircondition, which is unexpected. However, CO production lastedlonger than ~ 200 ms at O 2 condition below than 21% in the coalgasification, which resulted in more CO production. Theseresults clearly identify the process of coal combustion andgasification. This particle model can thus be considered forfurther investigation for various coal combustion andgasification applications.