Closed-loop Performance and Analysis of a Real Time Non-linear Bioreactor Process

Abstract

The bioreactor, a multivariable system, is the principle organ of biochemical Industrial processes where active microbial cells are grown and utilized for various useful biological products. To attain optimal growth of microbial cells a constructively designed bioreactor with an appropriate control method is essential. Nonlinearity is also an underlying property of the bioreactor that degrades the growth parameters and affects the biomass growth and its performance. IMC-PID based on Laurent series is employed in this paper for a real time bioreactor with the essential knowledge of its reaction kinetics and a complete understanding of its working. This paper explores the steady state and dynamic nonlinear behaviour of a typical bioreactor elaborately. To start with, an example of a multivariable fed-batch process of E.coli fermentation is considered for which the Relative Gain Array (RGA) and directional sensitivity are analyzed that provides proper I/O pairing. The Strongest input-output pair is identified and a nonlinear model is arrived using the SISO real time data. For fed batch E.coli fermentation, the closed loop performances are analysed using IMC-PID Laurent series method. Finally, the closed loop results are then validated by conducting real time experiments.