Effect of Dam Number of Straight Bar Plate on the Pulp Flow in the Low Consistency Disc Refiner

Straight bar refiner plates is a widely used type of plate for the disc refiner and the dam is the main structure of the plates. Its number and distribution will affect the refining quality and efficiency. In this paper, six straight bar refiner plates with different dam number were designed and the effect of dam number on the pulp flow in the refining zone during low consistency pulp refining were investigated by the method of Computational Fluid Dynamics using Fluent software. It showed that pressure decrease from the internal to external radius and the pressure obviously increase at the bar crossing point. And the pressure in the refining zone increases with the number of dams, which provide more compression on fibers, thus more fibrillation could be obtained. While it should be noted that more dams mean more resistance for pulp flow in refining zone. It was shown that the effect of dams on pulp flow velocity is partly, and it slows down the pulp radial velocity near dams and increase pulp tangential velocity. Meanwhile, the pulp residence time in refining zone will be increased due to existence of dams, but low velocity of pulp may block the groove which need to be considered when designing the refiner plates and refining system.KeywordsDisc refinerStraight bar plateDam numberPulp flowLow consistency refiningNumerical simulation