Energy savings in a rotary dryer due to a fuzzy multivariable control application

Rotary drying is one of the most common unit operations in industries. It is a complex nonlinear process, and it is difficult to control with conventional methods. In this paper, a fuzzy multivariable controller is designed for an industrial rotary drying system. This fuzzy controller is applied to a fertilizer production unit to save energy and improve its performance. Based on the dryer operating conditions, the proposed control system aims to keep the exhaust gas temperature at the dryer outlet as close as possible to the optimum value. Thus, a reduction in energy consumption is achieved without losing the quality of the final product. Practical aspects of the industrial reality, such as the plant lacking an online moisture measurement instrument, are considered. The results prove that the proposed fuzzy control is able to reduce biomass consumption by 9%, which represents an annual reduction of 648 tons of carbon dioxide (CO (2)) emissions to the atmosphere.