【作者】 赖艳萍；

【导师】 卢晓江；

【作者基本信息】 天津科技大学 ， 化工过程机械， 2006， 硕士

【摘要】 纤维长度对纸的质量影响很大，不同长度的纤维适合不同类型的纸张，为了获得所需要的纤维长度，提高经济价值，我们用圆柱形水力旋流器对纸浆纤维进行筛分。采用纤维质量分析仪对不同物料的纤维的长度进行了测定，并计算了纤维累积长度x和纤维长度分布密度f。研究了进料量Qf和分流比R(溢流与进料之比)对筛分的影响。实验发现在溢流中中等纤维所占的比例较多，底流中短纤维所占的比例较少。 从纤维受力分析入手，推导出离心场中柱形纤维的运动基本规律，研究了圆柱形水力旋流器筛分纤维的机理，为水力旋流器筛分纸浆纤维提供了理论基础。借助FLUENT软件，采用RNGκ-ε方程对水力旋流器的流场进行了数值模拟和理论分析。模拟出圆柱形水力旋流器内部流场的压力分布、速度分布等，得到稳定的流场后，再加上分散相—纤维，采用离散相模型来模拟纤维和水的分离情况。模拟结果表明，在溢流中，中等长度的纤维所占比例较多，长纤维和短纤维所占比例较小，在底流中短纤维所占的比例较大，长纤维所占比例较少，与实验情况基本吻合。本文得出的结论，为研究水力旋流器筛分纸浆纤维提供了理论基础，为工程实际应用起到一定的指导作用。更多还原

【Abstract】 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.更多还原