Picture of Ross TAYLOR, Clarkson University and ChemSepLogo of ChemSepWithin the 2nd CAPE-OPEN European Conference held in Como, Italy on February 17, 2005, Professor Ross TAYLOR of Clarkson University presented on ChemSep, a new CAPE-OPEN Unit Operation (PDF, 1183 Kbytes).

Ross reflected that while ChemSep is widely used in academia and also of interest to a number of industrial companies, especially because it features the original non-equilibrium column model, its usage by industry is very restricted. Ross went on summarizing the main features of the non-equilibrium model developed in ChemSep. He also mentioned that the rate-based column models found in various process simulation tools derive all from the model in ChemSep. In order to develop usage of ChemSep, making it a CAPE-OPEN Unit Operation pluggable in any CAPE-OPEN process simulator appeared as a suitable solution.

Ross went on describing the architecture given to ChemSep as a CAPE-OPEN Unit Operation. He pointed out that ChemSep model requires access to diffusion coefficients which are not often available from the thermodynamic servers in process simulators.Then a step-by-step demonstration was made of how it is easy to use ChemSep in Aspen Plus. The HDA flowsheet example is used as a starting point. One Aspen Plus block making use of the column model found in Aspen Plus library is replaced by a ChemSep instance.

Ross listed a number of issues with this implementation of ChemSep. First accessing thermodynamic properties through CAPE-OPEN interfaces greatly increases the CPU time necessary to solve a column in ChemSep. He restated that most process simulators do not provide binary Maxwell-Stefan diffusion coefficients while they are necessary to ChemSep. He also requested SMILES and UNIFAC structures to be made CAPE-OPEN property constants.

ChemSep has been tested in Aspen Plus, in Hysys and in COCO which he briefly showed as a process simulator coded by Jasper van BATEN and Richard BAUR. Ross is looking forward to develop in ChemSep three-phase non-equilibrium modelling, flow models and reactive distillation.