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A simplified two-dimensional (2-D) formulation for FCC risers has been developed. The model approximates the mixture of gasoil, steam, and solid catalyst that flows inside the riser reactor by an equivalent fluid with average properties. The cracking reactions are modeled by a 6-lump kinetic model combined with two energy equations (gas and solid). Due to the adopted simplifications, a fast and simple-to-solve computational code was written; nevertheless, it still is sufficiently precise to be used for the design of new units and for system control and optimization of operating conditions of FCC risers. The validation of the proposed model was performed by direct comparison of the obtained results with available experimental data for a multi-purpose pilot FCC riser unit. The model was then utilized to simulate an actual size industrial FCC riser. The obtained numerical results in this article demonstrate that the model can be used as a powerful and simple tool for design, control, and optimization of FCC units, combining accuracy with low computational time to obtain solutions when simulating actual FCC riser operation. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Inverse gas chromatography (IGC) was used to measure diffusion and thermodynamic parameters of volatile compounds in polymers. A comprehensive model for IGC is proposed, and a numerical solution for it is developed. Four capillary columns were prepared using PDMS and EPDM as the stationary phase. Toluene, ethanol, water, and some chlorinated compounds were the probes for the chromatographic experiments. Limitations of the IGC technique, although not reported in the literature, are explained. Nevertheless, the results for the systems chosen were satisfactory and agreed with the literature. The effect of adsorption on the column wall is important when water is used as a solute. The adsorption effect was incorporated into the model. The parameters obtained for water using the modified model became more reliable. The parameters obtained with IGC were used to get further understanding of the pervaporation process.