Energy optimization of a high consistency refiner process

Abstract

This paper presents a concept for energy optimization dealing with high consistency (HC) refining processes in the pulp and paper industry. Models for the outlet consistency and Gurley number used in the optimization are briefly described. The specific energy is used as manipulated variable. Additionally, the inlet consistency can be adjusted to a fixed value. While keeping the energy consumption as low as possible, it is still attempted to keep outlet consistency and Gurley number close to its desired value. The optimization uses a cost function with quadratic terms. An explicit solution for the optimization problem is derived. Additionally, the results are compared with findings from numerical optimization using a global search algorithm and an interior point method. Results presented are consistent with each other and indicate potential for energy savings.