Operability-Based Design of Energy Systems: Application to Natural Gas Utilization Processes

Process operability emerged in the last decades as a powerful tool for the design and control of complex chemical processes. The design of such processes is a challenging task as they are represented by nonlinear models with large numbers of differential and algebraic equations that demand high computational effort for their solution. In particular, process operability was proposed as a method for verifying the ability of a process design, defined by the available input set, to reach an achievable output set that considers production targets. However, existing operability methods for nonlinear systems are limited by the problem size that they can address.;In this thesis, a novel operability framework for process design and intensification of high-dimensional nonlinear chemical and energy processes is developed. This proposed framework bridges the gap in the literature by addressing the challenges of process nonlinearity and model size. This framework also broadens the scope of the traditional path of operability approaches for design and control, mainly oriented to obtain the achievable output set from the available input set, and compare the computed achievable output set to a desired output set. In particular, an optimization algorithm based on nonlinear programming tools is formulated for the high-dimensional calculations of the desired input set that is feasible considering process constraints, performance levels, and intensification targets. The high computational effort required for the high-dimensional calculations is addressed by the incorporation of bilevel and parallel programming approaches into the classical process operability concepts.;To illustrate the effectiveness of the developed methods, two natural gas utilization processes of different dimensionalities are addressed: i) a catalytic membrane reactor for the direct methane aromatization conversion to benzene and hydrogen, for which an intensified reactor design footprint reduction up to 90% when compared to the base case is obtained; and ii) a natural gas combined cycle system for power generation, for which a dramatic reduction in size, from 400 to 0.11 [MW], is produced by specifying conditions of the gas and steam turbine cycles, while still keeping the high net plant efficiency between 55 and 56.5 [%]. These results indicate that this novel operability framework can be a powerful tool for enabling process intensification and modularity. Moreover, results on the implementation of the bilevel and parallel computing methods show a reduction in computational time up to 2 orders of magnitude, when compared to the original results. The results in this thesis have culminated in four peer reviewed publications and four delivered presentations by the time of the defense

Approaches to solve a chemical industry supply chain problem : rule based system and hybrid programming

Orientador: Maria Teresa Moreira RodriguesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuímicaResumo: A Gestão da Cadeia de Suprimentos, metodologia com grande avanço e desenvolvimento no começo dos anos 90, tem como objetivo intensificar os benefícios e lucros de um sistema integrado de suprimento, produção e distribuição. A partir desse conceito, estratégias e decisões não são mais elaboradas sob a perspectiva de uma companhia somente, mas sim de todo o sistema de produção. Na literatura é comum encontrar diversas definições sobre essa metodologia de gestão, porém a maioria converge em ressaltar que esse sistema é altamente focado nas relações que existem entre toda a cadeia produtiva para prover o melhor nível de serviço ao cliente com o menor custo possível, construindo assim uma estrutura competitiva, interligando o mundo inteiro e sincronizando suprimento e demanda, conferindo performances globais. Dois elementos muito importantes na Gestão da Cadeia de Suprimentos serão estudados nesse trabalho, sendo eles: planejamento de demanda e ordem de compra, baseados em previsões de venda (sales forecast) por períodos definidos e controle de inventário; e a gestão da produção, envolvendo o planejamento e o sequenciamento dos produtos. A modelagem desses elementos é considerada por muitos como o maior desafio para os problemas de cadeia de suprimentos nos processos industriais, devido à alta complexidade e número de variáveis. Existem muitos estudos que vem tentando solucionar diferentes tipos de problemas como os citados anteriormente, com uma extensa gama de propostas para soluções, sendo essas puramente matemáticas ou híbridas, que utilizam de regras ou heurísticas. Diversos artigos sobre planejamento e sequenciamento da produção buscam por um indicador adequado para a otimização de sistemas de cadeia de suprimentos. Os mais encontrados são os de viés econômico, baseado no custo total da cadeia de produção no período estabelecido para o problema e a visão do cliente, baseado no nível de satisfação do cliente, podendo ser o tempo de entrega (lead time) ou percentual de atendimento. O objetivo desse trabalho é estudar duas abordagens diferentes para um problema de planejamento e sequenciamento de produção multiproduto, com um reator compartilhado, visando a otimização do atendimento ao cliente com o menor custo possível. A primeira abordagem é a de um sistema baseado em regras específicas e a segunda é uma solução com um sistema híbrido de modelagem matemática e heurísticaAbstract: Supply Chain Management, methodology with great improvement and development in early 1990, aims intensify profits and benefits in an integrated supply, production and distribution systems. From this concept, strategies and decisions are no longer created internally, but considering now a whole production chain. In literature is usual to find many definitions about this management methodology, but the majority emphasizes that this system is highly focused in the whole chain relationship to provide the best service level to customers, with lower possible price, building up a competitive structure and connecting the world. Two elements that are very important in Supply Chain Management will be studied in this paper: demand planning and purchase order, based on sales forecast and inventory control; and production management involving production scheduling. Modeling those elements is considered by many as the biggest challenge in industrial supply chain problems, due to the high complexity and quantity of variables. There are many studies trying to solve different kinds of problems with a huge variety of approaches to solve them, that could be purely mathematical or hybrid, using rules or heuristics. Several articles regarding production planning and scheduling search for a precise indicator to supply chain systems optimization. The most common ones are related to costs or profits, and customer satisfaction. This work objective is study two different approaches for a multi-product production planning and scheduling problem, with a single reactor shared, aiming optimize customer satisfaction with the lower possible cost. The first approach is a rule-based system and the second one is a hybrid system, containing mathematical model and heuristicsMestradoEngenharia QuímicaMestre em Engenharia Químic