Estudo e simulação de diferentes lógicas de controle de temperatura em processo fermentativo

Abstract

In this work, a study was carried out on the main types of process control logic, making comparisons and simulations focusing on temperature control of an alcoholic fermentation process in a bioreactor with a thermal jacket. Before proceeding to the mathematical modeling of the proposed system, a bibliographic review was made studing the motivation for using temperature control in fermentative processes, the theory of process and process control and finally the concept of three important control logics, onoff, PID and Fuzzy. To present the structure of a Fuzzy control, an introductory study was made on Fuzzy logic itself and how it can be used in process controls. The free software Scilab was used to simulate the compared logics. The results of the simulations made for the process in question indicated that the biochemical system behaved as expected, resulting in cell growth and ethanol production while the substrate is fed and then consumed. The results obtained also indicated that for conventional controller bioprocesses, which are dynamic systems, conventional controllers such as on-off and PID have some stability restrictions. On the other side, the results show that the Fuzzy logic can be adapted with good stability, although requiring a fine tuning by a specialist. Finally, it was possible to see in the result of each simulation that the system behaves within the predicted theory and thus make the relevant comparisons and conclusions.