Modelagem e análise dinâmica da incorporação do processo de produção de hidrogênio no setor sucroalcooleiro
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Data
2017-02-22
Autores
Llerena Pizarro, Omar Rosendo [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O processo de reforma a vapor de etanol produz normalmente um gás composto principalmente por hidrogênio (H2), monóxido de carbono (CO) e dióxido de carbono (CO2), fato que faz necessário inserir uma etapa de purificação para produção de hidrogênio puro. A tentativa de melhoria dessas tecnologias (reforma a vapor de etanol e purificação) tem motivado pesquisas centradas unicamente na concepção dos reatores, dando pouca atenção a sua modelagem matemática e a análise dinâmica aplicada ao controle. O controle do processo deve lidar com as não linearidades presentes na dinâmica do reformador e ser capaz de satisfazer a demanda de hidrogênio necessária em uma célula a combustível (CC), mantendo baixo ou eliminando o monóxido de carbono em vista da possibilidade de contaminação do eletrólito, que depende do tipo de tecnologia empregada. Neste trabalho estuda-se a modelagem matemática e análise dinâmica visando o controle do processo de reforma a vapor de etanol para a produção de hidrogênio puro, considerando também a etapa de purificação (reator catalítico + membrana de separação). Para a modelagem considera-se a aplicação das equações do balanço de massa e do balanço de energia (modelos). O modelo do processo é não linear e é representado por equações diferenciais parciais (PDE), as quais são convertidas em equações diferenciais ordinárias (ODE) pelo método de diferenças finitas antes de serem resolvidas. Para a análise dinâmica é realizado o cálculo dos pontos de equilíbrios e dos fatores de estabilidades, características essenciais que revelam se o sistema é estável ou não. Conclui-se das simulações que os modelos utilizados (EDO) tornaram possível observar o comportamento dinâmico do processo como um todo. No caso do reator catalítico observou-se como as concentrações de hidrogênio vão aumentando e as de água e etanol vão diminuindo, conforme os gases de síntese vão passando pelo reformador. Pode-se observar ainda da análise dinâmica, que o processo estudado tem um ponto de equilíbrio estável para um intervalo lógico de entradas de etanol e água, o que faz deste um sistema controlável.
The process of steam reforming of ethanol usually produces a gas composed mainly of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2), which makes it necessary to insert a purification step for the production of pure hydrogen. The attempt to improve these technologies (steam reforming of ethanol and purification) has motivated research focused solely on the design of reactors, paying little attention to their mathematical modeling and dynamic analysis applied to control. Process control must deal with the nonlinearities present in the reformer's dynamics and be able to satisfy the required hydrogen demand in a fuel cell (FC), keeping carbon monoxide low or eliminating in view of the possibility of contamination of the electrolyte , which depends on the type of technology employed. In this work, it is studied the mathematical modeling and dynamic analysis aiming at the control of the process of steam reforming of ethanol for the production of pure hydrogen, also considering the purification stage (catalytic reactor + separation membrane). For the modeling it is considered the application of a mass balance and energy balance equations (models). The model of the process is nonlinear and it is represented by partial differential equations (PDEs), which are converted into ordinary differential equations (ODE) by the finite difference method before being solved. For the dynamic analysis, the equilibrium points and the stabilization factors are calculated, essential characteristics that reveal whether the system is stable or not. It is concluded from the simulations that the models used (EDO) made it possible to observe the dynamic behavior of the process as a whole. In the case of the catalytic reactor, it was observed that hydrogen concentrations are increasing and that of water and ethanol are decreasing, as the synthesis gases are passing through the reformer. It can also be observed from the dynamic analysis that the studied process has a stable equilibrium point for a logical range of ethanol and water inputs, which makes it a controllable system.
The process of steam reforming of ethanol usually produces a gas composed mainly of hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2), which makes it necessary to insert a purification step for the production of pure hydrogen. The attempt to improve these technologies (steam reforming of ethanol and purification) has motivated research focused solely on the design of reactors, paying little attention to their mathematical modeling and dynamic analysis applied to control. Process control must deal with the nonlinearities present in the reformer's dynamics and be able to satisfy the required hydrogen demand in a fuel cell (FC), keeping carbon monoxide low or eliminating in view of the possibility of contamination of the electrolyte , which depends on the type of technology employed. In this work, it is studied the mathematical modeling and dynamic analysis aiming at the control of the process of steam reforming of ethanol for the production of pure hydrogen, also considering the purification stage (catalytic reactor + separation membrane). For the modeling it is considered the application of a mass balance and energy balance equations (models). The model of the process is nonlinear and it is represented by partial differential equations (PDEs), which are converted into ordinary differential equations (ODE) by the finite difference method before being solved. For the dynamic analysis, the equilibrium points and the stabilization factors are calculated, essential characteristics that reveal whether the system is stable or not. It is concluded from the simulations that the models used (EDO) made it possible to observe the dynamic behavior of the process as a whole. In the case of the catalytic reactor, it was observed that hydrogen concentrations are increasing and that of water and ethanol are decreasing, as the synthesis gases are passing through the reformer. It can also be observed from the dynamic analysis that the studied process has a stable equilibrium point for a logical range of ethanol and water inputs, which makes it a controllable system.
Descrição
Palavras-chave
Modelagem matemática, Análise dinâmica, Produção de hidrogênio, Reforma de etanol, Setor sucroalcooleiro, Mathematical modeling, Dynamic analysis, Hydrogen production, Ethanol reforming, Sugar and alcohol industry