Learning distillation by a combined experimental and simulation approach in a three steps laboratory: Vapor pressure, vapor-liquid equilibria and distillation column

Abstract

Distillation is one of the most important separation process in industrial chemistry. This operation is based on a deep knowledge of the fluid phase equilibria involved in the mixture to be separated. In particular, the most important aspects are the determination of the vapor pressures of the single compounds and the correct representation of the eventual not ideality of the mixture. Simulation science is a fundamental tool for managing these complex topics and chemical engineers students have to learn and to use it on real case-studies. To give to the students a complete overview of these complex aspects, a laboratory experience is proposed. Three different work stations were set up: i) determination of vapor pressure of two pure compounds; ii) the study of vapor-liquid equilibria of a binary mixture; iii) the use of a continuous multistage distillation column in dynamic and steady-state conditions. The simulation of all these activities by a commercial software, PRO II by AVEVA, allows to propose and verify the thermodynamic characteristics of the mixture and to correctly interpret the distillation column data. Moreover, the experimental plants and the data elaboration by classical equations are presented. The students are request to prepare a final report in which the description of the experimental plants and experimental procedure, the interpretation of the results and the simulation study are critically discussed in order to encourage them to reason and to acquire the concepts of the course.Two different questionnaires each with 7 questions, for the course and for the laboratory, are proposed and analyzed. The final evaluation of the students was strongly positive both for the course as a whole and for the proposed laboratory activities.