The Effect of Operating Variables on Mass Balance of Fiber Fractionation Using a Hydrocyclone, 2003 Fall Technical Conference

Often, fiber fractionation produces a higher-valued stream and a lower-valued stream, the disposal of which limits the practical use of the fractionation technology. Recently, however, a fractionation process has been developed involving screens and hydrocyclones that produce two high-valued streams: one useful in softness development for tissue and another useful in the development of strength for paper. The objective of this research was to understand the effects of fiber properties and hydrocyclone operating conditions on the fractionation of chemical pulps. The total and OD mass balances were determined around a single commercial hydrocyclone. In separate experiments, beaten and unbeaten pulp was fractionated using three different pressure drops and four different feed pressures. The total flow rate of the reject stream increased with the pressure drop and the feed pressure, whereas the total flow rate of accept stream remained constant. A single index using pressure drop divided by feed pressure described the total flow splits in the hydrocyclone, regardless of pulp type. It was found that the OD mass flow rate of fibers was affected by both the pressure drop and the feed pressure. As the feed pressure increased, the percent of fibers rejected increased. The beaten fibers always had a higher percent of fibers accepted for the same operating conditions as the unbeaten fibers. Future work will involve determining the fractionation efficiency of these pulps based on several fiber and pulp properties versus operating conditions.