A new method to calculate efficiency of randomly-packed distillation columns and its comparison with the methods utilized in ASPEN Plus

In this paper, a unique and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of randomly-packed distillation columns. This method has potential advantages; e.g., unlike all the available methods, it can calculate efficiency without using any empirical mass transfer and hydraulic correlations, and without the need to estimate the operational and hydraulic parameters of an operating column. It, therefore, will be free of errors and limitations of such empirical items and can be used for efficiency calculation of any random packing including new ones.Along with an analysis of the proposed method, the paper also presents a thorough analysis of the drawbacks and restrictions of the well-known mass transfer methods utilized in the commercially simulation packages such as ASPEN Plus. From these analyses, a number of main conclusions regarding the relationship of the mass transfer coefficients and of efficiency with the phase flow rates are drawn, and relevant recommendations are made for future research. It is also concluded that developing new methods based on rate quantities rather than flux quantities, like the one proposed in this study, can eliminate the necessity of estimating effective interfacial area for mass transfer calculations of an operating column.

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► A new method for calculation of mass and heat transfer coefficients and efficiency.
► Usable for efficiency estimation of any random packing in distillation columns.
► Free of errors and restrictions of empirical mass transfer and hydraulic correlations.
► Discussing restrictions of the well-known mass transfer method of Onda, available in ASPEN Plus package.
► Considering the relationship of mass transfer coefficients and of efficiency with phase flow rates.