Mechanism Study On The Fiber Fraction Of The Cylinder Hydrocyclone

The length of fiber is important to the quality of paper,and different kind of fiber is used to produce different kind of paper. In order to achieve the needed length fiber,fractionation of softwood pulp fiber were carried out with a cylindrical hydrocyclone. Pulp fiber length characterization in different streams have been examined using FQA. The effects of feed rate and split ratio (overflow rate to feed rate ratio ) on fractionation of pulp fiber are studied. It was found that most of long fiber were in the overflow stream,and most of short fiber were in the underflow stream.Based on an analysis of the forces on fiber, the nasic theory of cylindrical fiber in the centrifugual field were deduced,the mechanism study on the fiber fractionation were studied, which put a solid foundation on fiber fractionation. The internal flow field in a cylindrical hydrocyclone was simulated using commercial CFD software FLUENT and the k-ε RNG model, the distrubution of pressure and velocity were also obtained. After the stedy flow field was acquired, the performance of fiber seperation in hydrocyclone was stimulated using DPM model. It was found that most of long fiber were in the overflow stream, and most of short fiber were in the underflow stream,which agreed well with the experiment. The conclusion acquired in this paper no matter theory or engineering application will have importmant effect.