COMPUTER-AIDED PROCESS DESIGN AND OPTIMIZATION WITH NOVEL SEPARATION UNITS

This paper reports the results from the application of various methodo logies to generate and analyse process flowsheets with novel separatio n units. Novel separation processes in this paper include supercritica l extraction (SCE), melt crystallization (MC) and gas adsorption (GA). Application of a newly developed process synthesis technique has allo wed the identification of processes where mixtures to be separated sho w azeotropic behaviour and, therefore, are candidates for a SCE-based process. Design and optimization studies have revealed the feasibility of 'pressure-swing' distillation as well as SCE-based separation as p romising alternatives for these separations. In the case of MC, proces ses requiring separation/purification of compounds having specified li mits of viscosity and melting point have been identified as candidates for MC-based separation. In the case of GA, a knowledge-based analysi s is currently being developed for identification of potential candida te adsorbents and the corresponding gas-separation systems. Melt cryst allization could be identified as a substitute for distillation in acr ylic acid production. In acrylic acid production distillation resulted in an energy demand of 2.659 x 10(6) kJ/ton acrylic acid. Six differe nt cases of incorporation of melt crystallization as a partial or tota l substitute for distillation were analysed, and melt crystallization gave energy reductions in the range from 7.7 x 10(4) to 1.86 x 10(6) k J/ton acrylic acid. In a phenol production plant [9], the energy consu mption may be reduced from 8.68 x 10(6) kJ/ton phenol to 8.00 x 10(6) kJ/ton phenol by employing melt crystallization as a substitute for di stillation. For methylacetate production, novel separation schemes red uce the energy costs 1.4 times compared to the conventional separation schemes [9]. (C) European Communities 1997. Published by Elsevier Sci ence Ltd.