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In this paper, an evolutionary approach, improved CAMD based on the hybrid gene algorithm and simulated annealing algorithm (GASA), is developed. The new approach combines the feature of GA and SA, avoiding the problem of prematurity. With a new category strategy of candidate groups from the Mod UNIFAC group database adopted, a repair operator is introduced to guarantee the integrity of randomly generated molecules and thus the search of straight chain alkane as well as cyclane solutions can be performed together. The properties of molecules are obtained by the group contribution method. An example of extractive solvent selection for a methanol-methyl acetate system has been illustrated in detail to further explain the method. The stability as well as other properties of the molecules which the authors think important is considered in the fitness function. Results of the example show that the fitness ranking values are better than those in the literature. The CAMD method in this paper can be used in practical chemical processes. [ABSTRACT FROM AUTHOR]

A Reynolds mass flux model is proposedfor the simulation of CO2absorption into aqueous 2-amino-2-methyl-1-propanol(AMP)solutions in a packed column. With the proposed model, distributionsof concentration and temperature as well as velocity can be obtained.In the mathematical expression of the proposed model, the modeledReynolds mass flux equation is used to close the turbulent mass transferequation so that the generalized Boussinesq’s postulation isabandoned. The feature of the closure method is that the anisotropyof turbulent mass diffusion can be characterized. To validate theproposed model, a simulation is carried out for CO2-AMPabsorption in a randomly packed column. The simulated results arecompared with the experimental data in literature, and satisfactoryagreement is found between them. Besides, the anisotropy of turbulentmass diffusion characterized by the proposed model is discussed andfound to be consistent with that from experimental correlations. Finally,the simulations reveal that the anisotropic turbulent mass diffusionplays a significant role in the concentration distribution in a packedcolumn. [ABSTRACT FROM AUTHOR]

Concentration gradient-induced Rayleigh convections in the CO2 absorption process were investigated by the hybrid Lattice-Boltzmann/finite-difference method (LBM-FDM). The spatial scale effects on Rayleigh convection were studied by simulating Rayleigh convections with different liquid layers. The scale of convection increased with the liquid layer height but the average mass transfer coefficient showed the adverse tendency. The Rayleigh convection had a pronounced effect on the surface renewal. For better assessment of the renewal intensity, two statistical quantities were proposed. The transient variations of these quantities provided a good following feature with the mass transfer coefficient which confirms their accuracy and precision in characterizing the mass transfer process. [ABSTRACT FROM AUTHOR]