Correlation of beating intensity and characteristics of the valley beater with different beating elements

The characterization and understanding of intensity in refining or beating processes are crucial for fiber morphology change and process optimization. This paper takes the valley beater as the research subject, aiming to address the problem of intensity characterization in beating processes involving different beating elements and pulp consistencies. By analyzing the bar profile parameters of beating elements, a bar crossing model and the corresponding beating intensity model were constructed. Comparative analysis were then conducted on beating processes equipped with different rotors and pulp consistencies ranging from 0.3 % to 2 %. It was found that three intensities – net normal force per bar crossing zone ( f n net ), normal force per bar crossing length ( f BCL ), and normal force per bar crossing area ( f BCA ) – can effectively characterize the beating properties of different rotors with zero-bar angles, whereas the Specific Edge Load ( SEL ) is invalid. As pulp consistency increases, the normal force acting on individual fiber decreases, weakening the fiber-cutting effect. The study demonstrates that the curve of beating degree versus average fiber length change can characterize the intrinsic characteristics of the beating process, reflecting the balance between fiber cutting and fibrillation. When beating conditions are consistent, this curve directly reflects the intrinsic properties of the beating elements. By comparing three beating elements and validating results with water retention value (WRV), It was determined that the fiber fibrillation effect of No. Three rotor, with its lower intensity, is stronger compared to the others, while the fiber cutting effect follows the opposite trend. This research facilitates the intensity characterization of the valley beater’s beating process and provides a reference for optimizing refining processes of disc refiners, conical refiners, and similar equipment.