Partially sharing of active sites on char particle by multicomponent gasifying agent and detailed chemistry of water-gas-shift reaction are modeled and implemented. A three-dimensional RANS-based simulation with these models is also performed to investigate effects of a CO2 injection on gasification characteristics within an entrained flow coal gasifier. Results show that the gasification performance such as carbon conversion, product gas composition and gaseous temperature distribution is precisely captured by the present simulation. The reaction inhibition by the product gas and the reaction suppression by the multicomponent gasifying agent's partially sharing active sites are reasonably predicted. The effects of the CO2 injection on the gasification characteristics are also discussed in detail with considering contributions of reaction pathways to the gasification performance. It is revealed that it is essential to locally control exothermic gaseous reactions and endothermic heterogeneous reactions in order to take advantage of the CO2 injection. (C) 2014 Elsevier Ltd. All rights reserved.