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Study on a New System of Multi-stage Classification using an Almost Rigidly Rotating Flow

一种新的几乎刚性旋转流多级分级系统的研究

基本信息

批准号：
14550149
负责人：
TSUCHIDA Yoichi
金额：
$ 2.62万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550149/
关键词：
Centrifugal Classification Wet-type Classification Double-stage Classification Almost Rigidly Rotating Flow Internal Flow Axisymmetric Flow Stewatson Layer Ekman Layer 2段分級軸対象流スチュワートン層

项目摘要

We have studied a new wet-type centrifugal classification system that employs an almost rigidly rotating flow. This flow consists of geotropic interior regions, ageostrophic Stewartson and Ekman layers, and/or a rigid-rotation region. In this centrifugal system. we can accurately classify very fine feed-particles suspended in water with a low concentration into coarse and fine products by the difference in the centrifugal force and fluid drag exerting particles due to the difference in particle size, because we can increase the centrifugal force arbitrarily without producing any turbulent fluctuation and well manage the centrifugal force and the fluid drag. Hence, this system is adaptable to an accurate submicron classification.In the present study, we have treated, as the basis of the multi-stage system, a double-stage system that can classify feed particles into coarse, medium and fine products all at once. we have experimentally investigated the classification performance of both batch and semi-continuous types. Consequently, we have drawn the following conclusions, where a centrifugal-effect parameter characterizes the ratio of the centrifugal force acting on a particle to the fluid drag.(1) the semi-continuous type (both fine and medium products are obtainable continuously) shows a slightly greater coefficient of variation of the medium product than the batch type (only a fine product is obtainable continuously), but shows a smaller mass median diameter.(2) In both batch and semi-continuous types, with increasing centrifugal-effect parameter, the mass median diameter and coefficient of variation of the medium product become smaller, i.e. the medium product becomes finer and more uniform in particle size.(3) On the classification performance of each stage as a single-stage classifier, the stage with extraction shows a slightly worse classification accuracy than that without extraction.

本文研究了一种采用几乎刚性旋转流的新型湿式离心分级系统。该流由大地向性内部区域、地转性Stewartson和Ekman层和/或刚性旋转区域组成。在这个离心系统中。我们可以将悬浮在低浓度水中的非常细的饲料颗粒，通过颗粒大小的不同对颗粒施加的离心力和流体阻力的不同，准确地划分为粗、细产品，因为我们可以任意增加离心力而不产生任何湍流波动，并且可以很好地管理离心力和流体阻力。因此，该系统适用于精确的亚微米分类。在本研究中，我们以一种可以同时将饲料颗粒分为粗、中、细产品的双级系统作为多级系统的基础。我们对间歇式和半连续式的分类性能进行了实验研究。因此，我们得出了以下结论，其中离心效应参数表征了作用在颗粒上的离心力与流体阻力的比率。(1)半连续型（细产品和中产品都可以连续获得）中产品的变异系数略大于批量型（只有细产品可以连续获得），但质量中值直径较小。(2)间歇式和半连续式中，随着离心效应参数的增大，介质产品的质量中值直径和变异系数变小，即介质产品粒度更细、更均匀。(3)在各阶段作为单阶段分类器的分类性能上，有提取阶段的分类准确率略低于无提取阶段。