A study of the control of a bioreactor for the bioethanol production process

Abstract

This paper presents the results of numerical studies on the control systems of the bioethanol production process in a continuous stirred tank bioreactor. The studies included the bioreactor control by means of a nonlinear model predictive controller (NMPC) with constraints based on the process model. Particular attention was paid to the influence of the values of control signals generated by the controller on the metabolic changes taking place in biomass cells. These changes are initiated as a result of exceeding the permitted values of the process parameters. These values can be determined with the use of a developed method of numerical analysis of the mathematical model of the process. Their nature is related to the occurrence of points of change in the cell metabolic activity or the phenomenon of biomass washing out from the bioreactor. The NMPC control algorithm determines the optimal values of the control signals and searches only the given range of the control variables. As a result, the generated values of the control signals do not exceed the defined limit values, regardless of the nature and frequency of disturbances occurring in the system. This enables the process to be conducted in the area of optimal metabolic activity of microorganisms.