Dynamic Modeling and Control System Analysis for Continuous-Disc Filters in Pulp Mill Operations
Jose M. Campos-Salazar, Felipe Santander, Sebastian Larrain
Published: 2025/9/30
Abstract
Vacuum disc filtration is critical in pulp mills for white liquor clarification and pulp washing, involving tightly coupled dynamics between rotational speed, vacuum pressure, slurry concentration, filtrate flow, and cake thickness. These nonlinear interactions are often regulated using empirical methods, lacking formal modeling and control. This article develops a dynamic, multivariable model of a continuous-disc filter (CD-filter) system based on first principles, simplified to a single representative disc for tractability. A linearized state-space model supports the design of two control strategies: a decentralized PI-based scheme and a centralized model predictive control (MPC). MATLAB-Simulink simulations reveal that MPC outperforms PI in tracking accuracy, overshoot reduction, and disturbance rejection. A 3D efficiency surface illustrates the importance of coordinating inlet flow and solids concentration. Results highlight the need for advanced multivariable control in optimizing CD-filter performance.