Amaro Gomes Barreto

Neural Network Based Modeling and Operational Optimization of Biomass Gasification Processes

© 2012 de Souza et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Neural Network Based Modeling and Operational Optimization of Biomass Gasification Processes

Nonlinear model predictive control applied to the separation of praziquantel in simulated moving bed chromatography

An adaptive nonlinear model predictive control of a simulated moving bed unit for the enantioseparation of praziquantel is presented. A first principle model was applied at the proposed purity control scheme. The main concern about this kind of model in a control framework is in regard to the computational effort to solve it; however, a fast enough solution was achieved. In order to evaluate the controllers performance, several cases were simulated, including external pumps and switching valve malfunctions. The problem of plant-model mismatch was also investigated, and for that reason a parameter estimation step was introduced in the control strategy. In every studied scenario, the controller was able to maintain the purity levels at their set points, which were set to 99% and 98.6% for extract and raffinate, respectively. Additionally, fast responses and smooth actuation were achieved.

Modeling, Simulation, and Experimental Evaluation of Continuous Chromatographic Separation of Ketamine Enantiomers on MCTA

Abstract Results on the chiral separation of ketamine enantiomers by simulated moving bed (SMB) chromatography using microcrystalline cellulose triacetate (MCTA) columns are reported. Experimental data obtained with the SMB laboratory unit showed purities above 99.5% in the raffinate stream and above 97.7% in the extract stream. A simulation approach based on true moving bed (TMB) was applied to validate the performance of the SMB in steady state regime, taking into account the non-linear isotherms, non-ideal effects, and the non-homogeneities of the eight columns. The experimental and calculated results are in agreement with the internal profiles calculated by the TMB approach.

A modified Poisson-Boltzmann equation applied to protein adsorption

Ion-exchange chromatography has been widely used as a standard process in purification and analysis of protein, based on the electrostatic interaction between the protein and the stationary phase. Through the years, several approaches are used to improve the thermodynamic description of colloidal particle-surface interaction systems, however there are still a lot of gaps specifically when describing the behavior of protein adsorption. Here, we present an improved methodology for predicting the adsorption equilibrium constant by solving the modified Poisson-Boltzmann (PB) equation in bispherical coordinates. By including dispersion interactions between ions and protein, and between ions and surface, the modified PB equation used can describe the Hofmeister effects. We solve the modified Poisson-Boltzmann equation to calculate the protein-surface potential of mean force, treated as spherical colloid-plate system, as a function of process variables. From the potential of mean force, the Henry constants of adsorption, for different proteins and surfaces, are calculated as a function of pH, salt concentration, salt type, and temperature. The obtained Henry constants are compared with experimental data for several isotherms showing excellent agreement. We have also performed a sensitivity analysis to verify the behavior of different kind of salts and the Hofmeister effects.

SIMULAÇÃO NUMÉRICA DA ADSORÇÃO DE METANO E NITROGÊNIO EM LEITO FIXO CONTENDO SILICALITA

RESUMO – O presente trabalho trata da simulacao numerica da dinâmica de adsorcao de uma mistura binaria CH4/N2 em um leito fixo de adsorcao empacotado com silicalita. O modelo empregado e um sistema de equacoes diferenciais parciais, formado por balancos de massa e energia bem como equacoes algebricas, que traduzem equacoes constitutivas selecionadas. O modelo e resolvido empregando-se o metodo das linhas. Curvas de ruptura experimentais disponiveis na literatura foram usadas para a verificacao da capacidade de previsao, considerando-se a descricao de perfis obtidos com substâncias puras e com misturas binarias. A modelagem serve para nortear o dimensionamento de uma unidade de adsorcao em escala de bancada, oferecendo subsidios para a especificacao do sistema de troca termica e posicionamento de instrumentos analiticos para a medicao de temperaturas e composicoes.