Modelagem e otimização de energia em síntese deprocessos: desenvolvimento de modelos de programaçãomatemática para a ótima integração entre calor etrabalho

• Ano de defesa: 2014
• Autor(a) principal: Onishi, Viviani Caroline
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Departamento de Engenharia Química; Programa de Pós-Graduação em Engenharia Química; UEM; Maringá, PR; Centro de Tecnologia
• Palavras-chave em Português: Modelagem matemática; Otimização de processos; Integração de energia; Síntese de processos; Brasil.; Engenharias; Engenharia Química
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/3697

Conservation and energy efficiency are critical in processing plants, being achieved through optimized management of energy use. In this context, the optimal integration between heat and work can significantly reduce energy consumption and, consequently, the total cost of the process. In this way, four optimization models based on superstructures are developed for the energy integration in industrial processes. The first model presented in this thesis is a mathematical programming model for the detailed design of shell-and-tube heat exchangers. The proposed approach strictly follows the standards of TEMA (Tubular Exchanger Manufacturers Association), so that all geometric characteristics obtained for the equipment are standardized. The Bell-Delaware method is used to design the shell-side of the heat exchanger. Moreover, the superstructure is formulated in generalized disjunctive programming (GDP), and mixed-integer nonlinear programming (MINLP) to obtain standard equipment with heat exchange area and/or minimum total cost. The major contribution of this model relies in proposing a new sequential approach of optimization of partial objectives, in which the full set of design equations is divided into subsets, with the proposition of different objective functions based on heuristic knowledge of the process. The second optimization model refers to a model for the simultaneous synthesis of heat exchanger networks (HENs). The superstructure proposed to describe the process is formulated in GDP and MINLP, aiming to minimize the total annualized cost of the process. In this case, the objective function is composed by operating expenses and capital cost of investment in equipment. This model contributes significantly to the synthesis processes field because it incorporates the possibility of adjusting pressure levels of process streams, in order to improve the system heat recovery. Thus, the pressure recovery is performed in the simultaneously with the heat integration, so that the process conditions must be treated as optimization variables. Additionally, the model innovates by allowing the use of equipment for handling pressure coupled to the common axis, and the replacement of turbines by valves when thermo-economically favorable for the process. The third mathematical model is applied to the simultaneous synthesis of work exchange networks (WENs). In this model, an innovative concept, poorly explored in the available literature, is developed, focusing on the optimal integration between work and heat in industrial processes. Thus, the proposed new approach is analogous to the problem of HENs synthesis, in which the work integration occurs between streams at high-pressure and low-pressure in several pressure manipulation stages. The MINLP-based model allows simultaneous heat integration in the HEN, aiming to improve the pressure recovery process. In addition, the model considers the use of multiple units of single-shaft-turbine-compressor (SSTC), as well as stand-alone compressors, turbines and valves in order to minimize the total annualized cost of the network. The last MINLP-based model proposed is a mathematical model for the retrofit of HENs. The main contribution of this work is the use of pressure recovery of streams, to improve the heat recovery in existing networks. Therefore, the proposed superstructure enables the increase of the existing thermal exchange area, as well as the use of new equipment for heat exchange and pressure manipulation. In all developed models, case studies are conducted to verify the accuracy of their proposed approaches, including real industrial applications for the process synthesis models. In general, the results indicate that the proposed models accurately describe industrial processes for their intended use.