Flow behavior and coal gasification are simulated using the kinetic theory of rough spheres with the coal reaction models in a steam-assisted bubbling fluidized bed coal gasifier. The collisions of inelastic rough spheres are modeled based on the kinetic theory of rough spheres with gas-solid interactions. The fluctuation kinetic energy of particles is introduced to characterize the random motion of particles as a measure of the translational and rotational velocities fluctuations. The coal gasification models compose of devolatilization model, char gasification model and gas phase reaction model. Simulations are carried out in a steam-assisted fluidized bed coal gasifier with a height of 2.0 m and a diameter of 0.22 m. The gasification performance has been predicted, and the distributions of concentrations, velocities, temperatures of gas and solids phases and gas compositions are analyzed in a 2D model of a steam-assisted bubbling fluidized bed coal gasifier. Predicted gas species concentrations are in agreement with experiments. (C) 2014 Elsevier Ltd. All rights reserved.