Kinetic model and CFD simulation for an entrained flow coal hydrogasifier and influence of structural parameters

A comprehensive three-dimensional numerical model has been developed to for entrained flow coal hydrogasifier reactor. The kinetic model includes water evaporation, Johnson and Tran hydropyrolysis model, semichar reactions and secondary tar hydrocracking reactions. Numerical CFD(Computational Fluid Dynamics) simulation were performed using this model on a 6 t/d hydrogasifier reactor and the predictions are in good agreement with experimental results on coal conversion on a Dry Ash-Free (DAF) basis, overall carbon conversion, carbon conversions to the light hydrocarbon gases (LHGs, mainly methane) and the temperature at the outlet of the reactor. The performance of the reactor with different structural parameters (length-diameter draw ratio H/D, collision angle α, impinging distance h) was compared, including the flow field, temperature distribution and carbon conversion to various products. The results show that larger H/D, smaller collision angle and impinging distance are favorable for higher carbon conversion and CH4 production. But the influence of structural parameters on operating performance is not obvious.