| Two nonequilibrium stage models of multicomponent separation processes available in ASPEN PLUS (Aspen Technology, Inc.) and CHEMSEP (CACHE Corporation) commercial simulation programs are used to simulate six representative distillation columns with different internals, including 2 sieve tray, 1 bubble cap, 2 structured packing and 1 random packing columns.; In the nonequilibrium models, the component material and energy balance relations for each phase are solved simultaneously with the mass transfer rate equations and interface equilibrium equations. Their key features are the fluid mixing models and the mass-transfer coefficient correlations. Several methods to compute these factors have been evaluated.; The simulation results exhibit substantial differences when different combinations of mass-transfer coefficient and fluid mixing models are used. Likewise, the composition profiles of columns predicted by both simulators show good agreement when similar mass-transfer coefficient and fluid mixing models are used. |
