In this work we discuss the modeling and simulation of a fluidized bed coal gasifier which uses a mixture of coal and petcoke as its feed. A two phase model consisting of the bubble phase and the emulsion phase is used to describe the coal gasification process. We consider a non-isothermal model taking into account the effect of four heterogeneous reactions and four homogeneous reactions. We analyse the effect of various operating parameters such as composition of feed, location of feed point and ash content on the performance of the gasifier. The results of predictions of the simulations have been found to be in good agreement with the experimental results in the literature. It has been found that increase in petcoke content in the feed mixture tends to lower the efficiency and carbon conversion but increases the amount of syngas produced. Also, from the simulations, it has been found that increase in ash content of coal decreases the carbon conversion. We have concluded that the feed point of the solids should be above the point where O2 that is present in the bed gets exhausted, in order to obtain the maximum carbon conversion and efficiency. © 2010 Elsevier Ltd. All rights reserved.