The energy production from coal-fired power plant is increasing day by day, which result in increased CO2 emission from the existing power plant. However, CO2 emission from coal gasification can be reduced if an efficient CO2/O2/N2 coal gasification is implemented in IGCC system. Numerical simulations of coal gasification under CO2/O2/N2 gasification condition are carried out with the aim of describing the effects of model parameters, char reaction rates, operating conditions and heat losses to increase the syngas heating value and carbon conversion in a two stage entrained flow coal gasification process. The Eulerian–Lagrangian approach is applied to solve the Navier–Stokes equation and the particle dynamics. Finite rate/eddy dissipation model is used to calculate the rate of nine homogeneous gas-to-gas phase reactions. While only finite rate is used for the heterogeneous solid-to-gas phase reactions. It is found that the carbon conversions of combustor coal lie in the ranges from 97 wt% to 99 wt% for most of the calculated conditions. On the other hand, the carbon conversion of reductor coals varies from 45 wt% to 57 wt%. A noticeable change is obtained when the gasification occurs under a high temperature condition. Remarkable outlet results of about 32 wt% CO, 0.58 wt% H2 and 89 wt% overall carbon conversion are predicted if a high temperature of 1673K is maintained in the reductor. On the other hand, a reduced soot concentration is predicted if the O2 concentration and/or the reductor gas temperature increase(s) in the gasifier.