Study On Hybrid Process Of Batch Distillation-Adsorption

A novel operation mode of hybrid process of batch distillation-adsorption isproposed according to the advantages of batch distillation and adsorption, and then theintensive study on the new operation mode was made theoretically and experimentally.In the operation adsorption is added during the slop cut stage to reduce the slop cut.The operation is still batch distillation, because adsorption only assist to handle theslop cut. Compared with simple adsorption, the new hybrid mode not only reducesslop cut but also increases the yield of heavy components.The experiments of the operation mode were carried out with ethanol-isobutanol.Before experiments we need to choose the appropriate molecular sieve, and thendetermine the adsorption thermodynamics and kinetics model. Finally5A molecularsieve was chosen. Then carried out the static adsorption experiments under50℃,and fitted the static results. The results show that Langmuir and Freundlich modelwere fitting well, and indicate that the adsorption is monolayer adsorption. What’smore, the dynamic adsorption experiments were carried out, according to the fittingresults, the adsorption process follows pseudo-second-order kinetics equation.The relative mathematic model was setup for the new operation mode, and theprocess simulation was carried out by Matlab programming. The influence factors ofthe new operation mode were discussed by simulation, including different adsorptionswitch points. What’s more, the comparison between the novel operation and theconventional constant reflux ratio mode was conducted by simulation. The resultsshow that the new operation mode can reduce slop cut, which is during46.7%and71.5%. The simulation results of the yield of heavy components increase, which is9.3%in conventional constant reflux ratio batch distillation, and which is91.4%inthe hybrid process.The experiments of the new operation mode were carried out withethanol-isobutanol, in which the effect of different adsorption switch points.Compared with the constant reflux ratio mode, the new operation mode can reduceslop cut37.3%to63.5%. The yield of heavy components in conventional constantreflux ratio batch distillation is18.3%, and in the hybrid process is67.7%.Theexperimental results are consistent with the simulation results.