Standing Wave Design and Optimization of Nonlinear Four-Zone Thermal Simulated Moving Bed Systems

The standing wave design (SWD) and optimization method are developed for the first time for nonlinear thermal simulated moving bed (SMB) systems with significant mass-transfer effects. The design method was verified using computer simulations for two systems. The adsorption isotherms of fructose/glucose and p-xylene/toluene systems have weak and strong temperature dependence, respectively. The results show that nonlinear thermal SMB systems can simultaneously produce pure solvent as well as concentrated, high-purity products from dilute feeds. The condition that allows for production of pure solvent is determined from local equilibrium analysis. Optimization of ten decision variables to achieve minimum solvent consumption and maximum productivity takes less than 5 min using a laptop computer. The fructose/glucose thermal SMB system products are increased by >25% with solvent consumption decreased 2-fold. The p-xylene/toluene thermal SMB system product concentrations can be increased 10-fold while simultaneously producing pure solvents.