Simulation of Pressurized Ash Agglomerating Fluidized Bed Gasifier Using ASPEN PLUS

A model of a pilot scale pressurized Ash Agglomerating Fluidized Bed (AFB) Gasifier has been developed using ASPEN PLUS. The model is based on a sequential modular method with a recycle loop. Both hydrodynamics and reaction kinetics are considered simultaneously through FORTRAN codes if necessary. The physical properties of related gas and solid substance are calculated dynamically by the Peng-Robinson equation of state with Boston-Mathias alpha function (PR-BM) with in-line powerful physical property database in ASPEN PLUS, and then the calculated results are passed immediately to the fluid-dynamic correlations for space division. Therefore, only a few parameters are needed in this model. Different sets of pilot-scale experimental data are used to validate this model. The model predictions are in good agreement with experimental data at gas composition, carbon conversion, high heat value, cold gas efficiency, and dry gas yield. In addition, the effects of oxygen/coal ratio and steam/coal ratio on the gasification performance have been studied by this model. Within the calculation range, the oxygen/coal ratio should be lower than 0.55 N m(3)/kg. According to the intended final use, it is possible to have a molar H-2/CO ratio of two to one in the synthesis gas by controlling the suitable ratios of oxygen/coal and steam/coal.