Grant: Collaborative Research and Development Grants

Macroscale mixing and blending are the most common mixing processes used in pulp and paper manufacture. Fibre suspensions are agitated in large vessels to blend various furnish components, create uniformity in suspension composition and to modify fibre properties, such as remove latency. Current design of mixing chests is based on limited published information and on proprietary criteria held by mixer vendors and based on experience with installations. However, the quality of the mixing produced by these designs is rarely measured, and when measured is found to be far form ideal. The non-idealities affects the uniformity of the suspension, which adversely affects the runability of papermachines, the uniformity of chemical treatment in bleaching and the uniformity of finished products. The goal of this research project is to develop advanced design methods capable of predicting the dynamic performance for a wide range of mixing chests geometries and operating strategies. Suspension flow patterns within mixing chests will be characterized using novel experimental techniques (PIV, ultrasonic velocimetry and tomography), computational fluid dynamic (CFD) modeling and system identification tools. The models and tools will be validated through extensive experimental testing, both in a pilot-scale mixing facility and in industrial plants. Our findings will be transferred to the Canadian industry allowing them to improve the efficiency of their mixing operations and to increase competitiveness in the world marketplace, in particular by reducing manufacturing costs and improving the uniformity of the products produced.