Modelling and simulation of dual heating of substrate with centralized temperature control for anaerobic digestion process

Abstract

Biogas is a gaseous biofuel derived from the anaerobic digestion of waste products and is used in automobiles, residential heating, power generation, etc. The production of biogas depends on many factors, but temperature affects it most and plays a very crucial role. Therefore, any deviation from the optimum temperature is the main cause of concern in these plants. Temperature disturbance due to insertion of fresh feed and heat loss is very usual in biogas generation plants. Commonly, a single heating strategy along with PID based temperature control scheme is used in these plants. This paper focuses on the implementation of a dual heating strategy to handle temperature disturbances and heat loss. In addition, a blend of the feedforward-feedback control scheme is proposed to make the control robust, efficient and fast. Furthermore, a novel, Fuzzy-dual PID controller is also proposed to make the overall control centralized. The effectiveness of the proposed system has been tested at various realistic operating conditions. It is observed that the proposed dual heating with fuzzy-PID controller reduces the peak overshoot percentage, rise time and settling time for the digester temperature control. Results also prove the capability of the proposed fuzzy-PID controller in handling temperature disturbances. The overall system is modelled and simulated in a MATLAB/Simulink environment.