Modelagem e simulação da formação de hidratos de metano: um estudo do equilíbrio termodinâmico sólido-líquido-vapor

• Ano de defesa: 2007
• Autor(a) principal: Povoleri, Fernanda Barbosa
• Orientador(a): Oliveira, Luiz Nelio Henderson Guedes de
• Banca de defesa: Sacco, Wagner Figueiredo , Lage, Paulo Laranjeira da Cunha , Campos, Flavio Barboza
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Modelagem Computacional
• Departamento: Centro de Tecnologia e Ciências::Instituto Politécnico
• País: BR
• Palavras-chave em Português: Gás natural hidratos métodos de simulação; Gás natural hidratos - simulação por computador; Metano hidratos - métodos de simulação; Hidratos de metano; Hidratos de gás natural; Equilíbrio sólido-líquido-vapor; Regra das fases; Otimização matemática
• Palavras-chave em Inglês: Natural gas - hydrates - simulation methods; Natural gas - hydrates - computer simulation; Methane - hydrates - simulation methods; Methane hydrates; Natural gas hydrates; Solid-vapor-liquid equilibrium; Phase rule and equilibrium; Mathematical optimization
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::FISICO-QUIMICA::TERMODINAMICA QUIMICA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/13771

The objective of the present work is to present a study of solid-vapor-liquid three-phase equilibrium for methane hydrates. The analysis of three-phase equilibrium has several applications for water-hydrocarbon systems, since it permits, for example, determination of stability region for methane hydrates and natural gas hydrates. We have started seeking in literature about the state-of-art for thermodynamic behaviour and phase equilibrium for hydrates. And then the models proposed by Ballard (2002) and Zhang et al. (2005) were implemented. Zhang et al. (2005) have proposed a phase equilibrium for single-guest gas hydrates at temperatures below 300 K. Their approach has combined the van der Waals Platteeuw theory for the hydrate phase and the Peng Robinson equation of state for both fluid phases (vapor and aqueous phase) (1976) modified by Stryjek and Vera (1986). Ballard s (2000) approach has allowed the hydrate distortion from its standard state and has gave a more accurate composition of the hydrate and has improved hydrate formation predictions at high pressures. As a direct result of accounting for a changing hydrate volume, the cage radii were functions of the hydrate volume. Thus, Ballard have proposed the hydrate phase equilibrium by Gibbs energy minimization in a multi-phase flash routine. Thus, this work presents the Zhang et al. (2005) and Ballard s (2002) approaches for hydrate thermodynamic behavior and makes an analysis and comparison of them. To compute the flash problem, we use the tool lsqnonlin (built-in of MATLAB® software). The algorithm lsqnonlin is based on the Levenberg-Marquadt method.