The equilibrium model predicts the maximum yield when the reactants are in contact for an infinite time without taking into account the reactor type and size [76]. In reality, the products leave the reactor before having the opportunity to reach equilibrium so this type of model only provides the ideal yield. For practical applications, therefore, the use of the kinetic model is more realistic. At higher temperatures (>1,500 K), however, the use of the equilibrium model is more effective. There are two types of equilibrium modeling approaches: (1) stoichiometric or the use of the equilibrium constant; (2) non-stoichiometric or the minimization of Gibbs free energy method. In the stoichiometric model, all the chemical reactions and species involved are considered. For a known reaction mechanism this method predicts the maximum yield of all the products and the possible limiting behavior of the reactor. In the

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and Mahinpey developed a model capable of predicting the performance of an at­mospheric fluidized-bed gasifier [83]. They used both built-in Aspen Plus reactor models and external FORTRAN subroutines for hydrodynamics and kinetics to sim­ulate the gasification process. Other authors have worked with Aspen Plus to model the gasification process for coal and biomass. Yan and Rudolph developed a model for a compartmented fluidised-bed coal gasifier process [86], Sudiro et al. modeled the gasification process to obtain synthetic natural gas from petcoke [87]. Abdeloua — hed proposed a compressive model for dual fluidized bed gasifier modeling with ASPEN Plus [88]. A comprehensive review on Biomass gasification simulation also provided by Puig-Arnavat et al. [90] (Fig. 10.3)