A User-Defined Pervaporation Unit Operation in AspenPlus© on the Basis of Experimental Results from Three Different Organophilic Membranes

Abstract

Simulation is an important tool to balance, compare and investigate processes. Due to new investigations and the variety of processes not every process step is available as unit operation in simulation software. Absence of unit operations is evaded with help of simplifications, assumptions and usage of similar process steps. At best unit operations should calculate in and outlet streams based on sophisticated models according to the theory in literature. Therefor the aim of this work was to generate a pervaporation unit operation on the basis of experimental results working on AspenPlus© platform. Per-vaporation as a thermal membrane process step is gaining more and more interest from researchers in the last decades. The possibility to separate close boiling point, heat sensitive and azeotropic mixtures opens a big field for industrial application (Shao et al., 2007). Additionally energy savings are possible when effective process combinations are implemented (Vane, 2005). The membrane, as the heart of the pervaporation process, is currently the limiting factor. Despite high membrane costs, membrane fouling is also one big disadvantage. Therefore investigation of different membranes is also in focus of research works. The potential energy savings offered when using pervaporation can be determined at its best, when the process step is investigated in simulation software. The aim of this work should enable this possibility to generate a pervaporation unit operation on the basis of experimental results. Therefore three different organophilic membranes were investigated on a laboratory setup. Influences like feed temperature, feed concentration, Reynolds number in the module and applied vacuum pressure were varied. The gained results offer a data set to regress membrane and component specific permeances depending on the investigated parameters. The same experiments with all three membranes were carried out in the laboratory. A sequence from the trials is used to regress permeance models for each membrane and component. These regression models were implemented in the user defined unit operation. In the unit operation mass transport and simple heat balance including evaporation are considered. As a result three unit operations with different membranes are available for simulation. Validation of the experimental results shows very good accordance with all three investigated membranes. The aim of a first estimation of the pervaporation step in the simulation software is reached. The results of this work enable the connection of the pervaporation unit operation in global process sheets and hybrid combinations.