Characterization of the low consistency pulp refining conducted by the plates with different bar-groove width ratios

Abstract Isometric straight bar refiner plates are extensively employed in low-consistency pulp refining, and a special type of these plates features different bar-groove width ratios ( a / b ) while maintaining a constant sum ( a + b ). Previous studies have demonstrated that the Specific Edge Load (SEL) fails to serve as a valid metric for comparing the refining intensities of pulp refining when such plates are utilized. This study systematically investigates the interrelationships among SEL, Specific Surface Load (SSL), Modified Edge Load (MEL), and related parameters, to identify refining intensities suitable for characterizing refining processes conducted by plates under constant ( a + b ) with variable ( a / b ),and proposing more robust metrics. Key findings reveal that neither SEL nor the net tangential force per bar crossing zone ( f t net ) effectively measures refining intensity in this configuration. Although MEL and SSL demonstrate empirical utility, their physical meaning remains limited. Instead, the net equivalent tangential or normal force per bar crossing zone, modified by the equivalent number of bar crossing zones ( N ’ BC ), emerges as a more robust metric. Futhermore, the net average shear stress ( τ τ net ), normal pressure ( p n net ), and net force per bar crossing length which are modifications of f t net or net normal force per bar crossing zone ( f n net ) in terms of bar crossing area and length, provide viable alternatives. Therefore, the net force per bar crossing zone exhibits significant potential as a universal intensity metric for characterizing a wider range of refining processes, as it can be modified based on bar crossing parameters.