Fuzzy and three-step control of refiner system to get stable freeness for recycled paper

This paper presents the design of refiner control system for recycled paper stock preparation as a complete solution to fulfill refiner control requirements. This control system is based on Specific Energy Consumption (SEC) control (indirect freeness control) providing uniform refining during production range changes or changes in consistency and flow. In addition, SEC controller provides minimizing paper breaks, optimizing energy consumption and maximizing overall quality. The designed controller includes some interlocks that are very important for refining control systems such as low and high pressure, insufficient stock flow, low consistency and automatic unloading limit values. The system is equipped with two types of controllers which are power controller and SEC controller. Fuzzy and three-step algorithms for control process have been developed in the microcontroller unit. C++-based software was developed to communicate between the host computer and the designed microcontroller unit over the RS232 interfacing unit.