Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Methods and tools for process optimisation using membranes

In almost all chemical and petrochemical processes separations are used to purify the feed stock, fractionate components, remove impurities from a mixture or to improve the efficiency of a process. The thermodynamic efficiency of most separation processes and especially distillation is very poor. By using membranes much better efficiencies are obtained and major energy (and cost) savings are expected when membranes replace distillation. Examples are pervaporation to separate water or methanol from organic liquids or the separation of hydrogen from process mixtures. Especially the use of membranes in a membrane reactor in which hydrogen is separated from a reaction mixture in order to shift the equilibrium of the reaction will lead to very favourable economics of a process. Examples of such processes are dehydrogenation reactions, water gas shift reaction and steam reforming.

To assess the advantage of using membranes in membrane reactors many long and expensive experiments are needed. These experiments can be minimised and supported by process engineering and flowsheeting calculations. By such computer simulations give quick and effective insight in the technical en economic potential of using membranes and membrane reactors in processes. Several tools have been developed, starting with rather simple spreadsheet (MS-Excel) calculations to highly sophisticated process modelling in the flowsheeting package ASPEN+. As the flowsheeting package ASPEN+ does not contain membranes or membrane separation as unit operation, FORTRAN codes describing the membrane performance, reactor performance and combined heat and mass transfer have been developed for dehydrogenation and water gas shift reactions and they have been implemented in ASPEN+. The models can simply be extended with other type of reactions like steam reforming but also esterification reactions. With this toolbox several processes have been evaluated.

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