Overall Efficiency Evaluation of Commercial Distillation Columns with Valve and Dualflow Trays T. L. Domingues Basic Petrochemical Unit, Braskem S.A., Triunfo, RS - Brazil A. R. Secchi Chemical Engineering Program, COPPE/UFRJ, Rio de Janeiro, RJ - Brazil T. F. Mendes Dept. of Chemical Engineering, UFRGS, Porto Alegre, RS - Brazil DOI 10.1002/aic.12166 Published online January 20, 2010 in Wiley Online Library (wileyonlinelibrary.com). The main objective of this work is to establish appropriated ways for estimating the overall efficiencies of industrial distillation columns with valve trays with downcomer and dualflow trays. The knowledge of efficiencies has fundamental importance in the design and performance evaluation of distillation columns. Searching in the literature, a tree of alternatives was identified to compose the tray efficiency model, depending on the mass transfer models, the liquid distribution and vapor flow models on the tray, the liquid entrainment model, the multicomponent mixture equilibrium model, the phys- ical properties models, the height of froth on the tray model and the efficiency defini- tion. In this work, different methods to predict the overall efficiency of distillation col- umns with valve and dualflow trays were composed and compared with data from three commercial distillation columns under different operating conditions. The models were inserted in the Aspen Plus 12.1 simulator, in Fortran language, together with tray geometrical data, fluid properties and operating data of the distillation columns. For each column, the best thermodynamic package was chosen by checking the tem- perature profile and overhead and bottom compositions obtained via simulation against the corresponding actual data of industrial columns. A modification in the fraction of holes evaluation that is jetting parameter of the Garcia’s hydraulic model of dispersion above the tray was proposed. This modification produced better results than the original model to predict the fraction of holes that are jetting and in the effi- ciency of dualflow trays and similar results to Garcia model in the efficiency evalua- tion of valve trays. V V C 2010 American Institute of Chemical Engineers AIChE J, 56: 2323– 2330, 2010 Keywords: distillation columns, tray efficiency, hydrocarbon processing Introduction In the petrochemical industry, trayed column is one of the most used equipment in the separation of liquid mixtures Correspondence concerning this article should be addressed to A. R. Secchi at arge@peq.coppe.ufrj.br. V V C 2010 American Institute of Chemical Engineers AIChE Journal 2323 September 2010 Vol. 56, No. 9