INVESTIGADORES
PEREDA Selva
congresos y reuniones científicas
Título:
Thermodynamic Design and Optimization of Supercritical Hydrogenation Processes
Autor/es:
S. PEREDA; S. DIAZ; S.B. BOTTINI; E.A. BRIGNOLE
Lugar:
Foz de Iguazú
Reunión:
Conferencia; VI Iberoamerican Conference on Phase Equilibria for Process Design - EQUIFASE 2002; 2002
Institución organizadora:
Universidad Federal de Rio de Janeiro - Universidad Nacional del Sur - CONICET
Resumen:
Catalytic hydrogenation processes are common in the food and pharmaceutical industry. When the substance to be hydrogenated and/or the reaction product is a liquid, the reaction rate and selectivity are limited by the low solubility of hydrogen and high mass transfer resistance in the liquid phase. The addition of a supercritical solvent can bring the reactive mixture to a homogeneous supercritical phase and give rise to great improvements in the reaction rate and quality of the product (Harrod and Moller, US Patent 5 962 711, 1999). The selection of the adequate supercritical solvent and process operating conditions is a typical phase equilibrium engineering problem. For a given problem and process constrains, the systematic application of phase equilibrium tools allows the search of appropriate operating conditions. For the supercritical hydrogenation problem the process restrictions are given by: (a) components of the reactive mixture; (b) range of reaction temperature; (c) degree of conversion; (d) purity of products. The process operating conditions should guarantee: (a) the existence of a single-phase reactive mixture at the reactor; (b) the specified purity of products in the separation units downstream de reactor. In the present work the phase equilibrium engineering tools are applied to the design of two supercritical hydrogenation processes: the hydrogenation of vegetable oils to produce margarine and that of fatty esters to produce fatty alcohols. Phase equilibrium calculations were carried out with the group contribution equation of state GCA-EoS (Gros et al., Fluid Phase Equilibria. 116, 535, 1996). The equation was included as the thermodynamic support of a rigorous sequential process simulator, integrated to an optimization algorithm (Diaz et al., Computers and Chemical Engineering, 24, 9, 2069, 2000) The optimization problem for the different supercritical process schemes has been formulated as a nonlinear programming (NLP) model, solved with a successive quadratic programming algorithm (Biegler and Cuthrell, Com. Chem. Eng. 9, 257, 1985). The optimization variables are the amount of solvent fed to the reactor and the temperature and pressure in each process unit. The objective function is the minimization of energy consumption.