Detail Mass transfer, kinetics and rate-based modeling of reactive absorption Bibliografi Author: Pacheco, Manuel Antonio ; Rochelle, Gary T. (Advisor) Topik: ENGINEERING; CHEMICAL Bahasa: (EN )    ISBN: 0-591-91722-X     Penerbit: THE UNIVERSITY OF TEXAS AT AUSTIN     Tahun Terbit: 1998     Jenis: Theses - Dissertation Fulltext: 9838074.pdf (0.0B; 1 download) Abstract A mass transfer model was developed to describe the rates of mass transfer of reactive absorbing gases. This model is based on the Danckwerts surface renewal model and uses the concept of time-mean concentrations. The diffusion of reactants and products through the liquid boundary layer, reversibility and interaction between the different chemical reactions is accounted for by the model. The model was applied to reactive absorption of CO$/sb2$ into diglycolamine and methyldiethanolamine and blends of these reactive solvents. The electrolyte NRTL thermodynamic model was used to account for the non-ideality of the gas-liquid systems. The model was validated using rates of mass transfer measured in a wetted-wall column reactor at $25/sp/circ$C to $100/sp/circ$C with CO$/sb2$ loading varying from 0.015 to 0.55 moles CO$/sb2$/moles of reactive solvent. It was found that the reversibility of the chemical reactions affects the mass transfer rate at temperatures as low as $60/sp/circ$C. The interaction between the diffusion of reactants and products, the reversibility of the chemical reactions, and the electrolyte interaction parameter $/tau$(water, DGACOO$/sp-$-MDEAH$/sp+$) was found to be crucial for predicting the mass transfer rates, especially at temperatures above $60/sp/circ$C. The mass transfer model was integrated to simulate the selective absorption of H$/sb2$S from a gas stream containing CO$/sb2$ using aqueous methyldiethanolamine. A general framework was developed to model the transport processes that take place during reactive absorption when both rate and equilibrium-controlled reactions occur in the liquid phase. A rate-based distillation column module, $/rm RATEFRAC/sp/circler,$ was used for the column integration. The Maxwell-Stefan approach to multicomponent mass transfer and the enhancement factor theory were utilized. It was found that in packed columns CO$/sb2$ absorption is controlled by diffusion with fast chemical reactions; in trayed columns it is controlled primarily by physical absorption. Gas-film resistance is never significant for CO$/sb2$ absorption. For H$/sb2$S absorption gas and liquid-film resistances are important, and diffusion of bisulfide controls the liquid-film resistance. Heat effects produce temperature bulges which can cause equilibrium 'pinches' at the maximum temperature. This gives an optimum packing height for the H$/sb2$S removal. Trayed columns perform better than packed columns for H$/sb2$S removal, primarily because of the larger number of mass transfer units. ftn$/rm RATEFRAC/sp/circler$ is property of Aspen Technology Inc. and Koch Engineering Company Inc. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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