CFD Modeling and Validation of Oxy-Fired and Air-Fired Entrained Flow Gasifiers

Environmental drivers like carbon capture and other emission controls are creating a great opportunity for growth and adoption of clean coal technologies. Gasification is one of the more established and matured clean coal technologies and numerical simulations are playing crucial role in its development. Different models and approaches have been proposed and discussed in the literature. In the present work, a step by step approach is proposed to evaluate the fractions of different species as a result of volatile break-up during gasification. The volatile component of a given solid fuel like coal or biomass consists of Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur. Mass of these elements in the evaluated species is balanced with their individual masses in the original solid fuel composition. CFD simulations for ConocoPhillips' EGas technology based gasifier and Mitsubishi Heavy Industries (MHI) research scale two stage air blown gasifierare performed including volatile break-up evaluated using current approach in ANSYS FLUENT 14.5. The reaction rates are computed using the Finite rate/Eddy dissipation reaction model. The Discrete Ordinates radiation model with Weighted Sum of Gray Gas Model (WSGGM) for gas absorption coefficient along with particle radiation interaction is employed in these simulations. The predicted syngas composition and exit temperature are compared with the experimental results. The simulation predictions are within 10% of accuracy compared to the experimental measurements