The use of dams in low consistency stock preparation refining

The most accepted theory of refining is the intensity theory, which stares that the more intense the impact of the bar crossings, the more fiber cutting that occurs. While the theory is useful in evaluating refiner plate designs, it does have some limitations. It does not take into account the effect of refining variables such as volumetric flowrate, consistency, and pH. It also does not take into account certain design features, such as dams and bar angle. This paper looks at the effect of the use of darns in the refining process. Darns cause suboptimal refining changing the flow characteristics in the grooves and bar surfaces. The results given will show how much of an effect is generated when applying these tools, and how the refiner intensity theory does not account for these effects.