COMPOSITIONS CALCULATION OF COMPLEX DISTILLATION SYSTEM PRODUCT FLOWS BASED ON THE EXTENDED VERSION OF THE MAXIMUM ENTROPY PRINCIPLE

Abstract

A method for calculating the most likely product compositions of athermal mixture separation in complex distillation systems, including systems of simple recycling and non-recycling columns, complex columns with side sampling, systems with joint heat flows, and others. The method is based on an extended version of the maximum entropy principle. The informational entropy of complex experiment involving conditional entropy and conditional probabilities is used as the likelihood criterion. The adopted axiomatic allows one to obtain the most probable component distributions in the product flows of the system, which corresponds to the complex experience maximum entropy in accordance with the balance restrictions. It has been demonstrated that athermal properties accounting of the mixture create dependencies that include entropic activity coefficients associated with the conditional entropy in a typical thermodynamics form. Dependencies are a special case of the correlations obtained for ideal mixtures. The method for calculating the entropy activity coefficients as functions of the components molecule relative volumes and the mixture molar composition has been provided. This method is focused on the design version of the distillation system calculation. It allows to determine the parameters characterizing the process length (the number of theoretical separation steps in the non-selective mode) and the product flow composition products under the product quality restrictions. The accounting of mixture athermal nature leads to an increased duration of the process and has a slight impact on the product compositions. A comparison is given of the results of the calculation of the composition of the product flows of a typical gas fractionating unit with and without taking into account the athermal properties of the mixture to be separated with the data of an industrial experiment.