Several models have been proposed to simulate the reaction chamber of an entrained flow gasifier. Van der Burgt uses a simple model based on constant fuel conversion ratio (that avoids the simulation of the gasification process) and gas phase equilibrium [15]. Wen proposes a model based on the division of the gasification process into three stages (volatilisation and volatiles combustion, char combustion and char gasification) and in the simulation of gas-particle interactions by using an unreacted-core-shrinking model [16].
Since the gasifier has been built, a CFD model that provides the value of properties in all the gasifier is not mostly needed. However, dependence of fuel conversion ratio with operation conditions should be considered. To do so, a model has been developed that simulates the gasification process suffered by a fuel particle. This model uses the process division proposed by Wen but have some differences. First of all, it takes sulphur into account (which is a very important issue due the high sulphur content of the fuel used by Elcogas IGCC power plant). Second, it considers two isothermal zones, one for the first and second and the other for the third stage.