| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 3.83 MB | Adobe PDF |
Advisor(s)
Abstract(s)
O avanço tecnológico realizado na indústria química tem levado a processos cada vez mais complexos, com múltiplas variáveis a controlar e restrições processuais a impor em cada processo. Outra necessidade que a indústria tem passa pelo aumento da eficiência dos processos, reduzindo os custos associados a mesma. Dada a grande competitividade no meio, a comunidade científica e industrial começou a explorar profundamente o controlo de processos, de maneira a criar sistemas de controlo mais avançados, capaz de lidar com as exigências processuais.
Nisto surge então o controlo preditivo baseado em modelos matemáticos, denominado por MPC, em que este tipo de controlo engloba diversas classes de controladores que utilizam algoritmos de predição e modelos matemáticos próprios de cada sistema, o que permite que o processo opere perto dos valores máximos das restrições processuais, de maneira eficiente e segura.
Como descrito na literatura, o MPC apresenta grande sucesso em sistemas lineares com restrições dada a capacidade do mesmo de reduzir o problema de otimização a um problema de programação quadrática. Com esta capacidade, torna-se mais fácil a sua resolução e implementação, como será apresentado neste trabalho. Como consegue lidar com sistemas multivariáveis, fica igualmente mais flexível e mais robusto que o controlo clássico, algo que também será abordado neste trabalho.
No presente trabalho, aplicou-se uma das técnicas de controlo preditivo a um equipamento que é comum a indústria química, um permutador de calor de tubos concêntricos. Além da aplicação destas técnicas, aplicaram-se também técnicas de controlo clássico e compararam-se os dois tipos de controlo. A aplicação dos dois tipos de controlo foi feita através de simulação e implementação num sistema real.
A necessidade do modelo matemático do permutador de calor levou a necessidade de um estudo aprofundado aos problemas de transferência de calor, bem como os modelos gerais dos vários permutadores de calor.
Uma outra técnica desenvolvida neste trabalho é a capacidade de ligar um computador de uso pessoal a uma instalação de escala laboratorial, com resultados positivos após a implementação.
The technological advances made in the chemical industry has led to increasingly complex processes, with multiple variables to be controlled and procedural restrictions to impose in each process. Another need that the industry has is to increase the efficiency of processes, reducing the costs associated with it. Given the great competitiveness, the scientific and industrial community began to deeply explore process control to create more advanced control systems capable of dealing with procedural requirements. In this, the predictive control based on mathematical models, called MPC, arises, in which this control encompasses several classes of controllers that use prediction algorithms and mathematical models of each system that allow the process to operate close to the maximum values of the procedural restrictions, efficiently and safely. As described in the literature, the MPC shows great success in linear systems with constraints given its ability to reduce the optimization problem to a quadratic programming problem. With this capability, it becomes easy to implement and easy to resolve, as it will be presented in this paper. Because it can handle multivariate systems, it becomes more flexible and more robust than classical control, something that will also be addressed in this paper. In the present work, these predictive control techniques were applied to equipment that is common to the chemical industry, a double pipe heat exchanger. In addition to the application of these techniques, classical control techniques were also applied, and the two types of control were compared. The application of the two types of control was done through simulation and implementation in a real system. The need for the mathematical model of the heat exchanger has led to the need for an in-depth study of the heat transfer problems as well as the general models of the various heat exchangers. Another technique developed in this work is the ability to connect a personal computer to a laboratory scale installation, with positive results after implementation.
The technological advances made in the chemical industry has led to increasingly complex processes, with multiple variables to be controlled and procedural restrictions to impose in each process. Another need that the industry has is to increase the efficiency of processes, reducing the costs associated with it. Given the great competitiveness, the scientific and industrial community began to deeply explore process control to create more advanced control systems capable of dealing with procedural requirements. In this, the predictive control based on mathematical models, called MPC, arises, in which this control encompasses several classes of controllers that use prediction algorithms and mathematical models of each system that allow the process to operate close to the maximum values of the procedural restrictions, efficiently and safely. As described in the literature, the MPC shows great success in linear systems with constraints given its ability to reduce the optimization problem to a quadratic programming problem. With this capability, it becomes easy to implement and easy to resolve, as it will be presented in this paper. Because it can handle multivariate systems, it becomes more flexible and more robust than classical control, something that will also be addressed in this paper. In the present work, these predictive control techniques were applied to equipment that is common to the chemical industry, a double pipe heat exchanger. In addition to the application of these techniques, classical control techniques were also applied, and the two types of control were compared. The application of the two types of control was done through simulation and implementation in a real system. The need for the mathematical model of the heat exchanger has led to the need for an in-depth study of the heat transfer problems as well as the general models of the various heat exchangers. Another technique developed in this work is the ability to connect a personal computer to a laboratory scale installation, with positive results after implementation.
Description
Trabalho final de mestrado para obtenção do grau de mestre em Engenharia Química e Biológica
Keywords
Controlo preditivo Predictive control Modelo espaço-estado Space-state model Permutador de calor Heat exchanger Sistemas multivariáveis Multivariate systems Controlo clássico Classic control
Citation
FERREIRA, Ricardo Jorge Felizardo - Controlo de temperatura num permutador de calor de tubos concêntricos : uma abordagem clássica vs uma abordagem preditiva. Lisboa: Instituto Superior de Engenharia de Lisboa, 2018. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa