气力输送方式的分类及划分界限的确定 Ⅰ.分类标准及分类  

CLASSIFICATION OF PNEUMATIC CONVEYING MODES AND DEMARCATING CRITERIA:A RRVIEW I.Classification and Criteria

作　　者：洪江[1] 

机构地区：[1]北京科技大学429信箱,北京100083

出　　处：《化工冶金》1993年第1期79-89,共11页

摘　　要：本文在对现行5种分类标准评述的基础上,提出可在 Zenz 型相图上以表观气体速度 U_g 为分类标准,以沉积速度 U_s、临界速度 U_c、噎塞速度 U_(ch)和最小流化输送速度 U_m为划分界限对气力输送方式作如下分类:对水平管输送,稀相(U_s<U_g)、中相(U_c<U_g<U_s)、密相(U_g<U_c)且至少有一个以上管截面被固体充满)和"死区"(U_g<U_c 且以不稳定分层流型输送);对噎塞型垂直管输送,稀相(U_(ch)<U_g)、密相(U_m<U_g<U_(ch))和移动床输送(U_g<U_m).非噎塞型垂直管输送系统因尚未弄清流型转变过程而很难在 Zenz 型相图上进行分类.In this paper,five conventional demarcating criteria for pneumatic conveying modes are reviewed.A new classification principle suitable for theoretical and applied research is proposed employing superficial gas velocity U_g as classifying index and saltation velocity U_s,critical velocity U_c,choking velocity U_(ch) and minimum velocity of fluidized flow U_m as demarcating critical values in the Zenz-type phase diagram which describes the characteristics of gas-solid two-phase flow in pipes.For horizontal pneumatic conveying,the diagram consists of dilute phase(U_s<U_g),medium phase (U_cU_g<U_s),dense phase(U_g<U_c)with the pipe full at one or more cross-sections,'dead zone'(U_g<U_c)with unstable stratified flow.For choking vertical pneumatic conveying,dilute phase(U_(ch)<U_g),dense phase (U_m<U_g<U_(ch)), moving bed conveying(U_g<U_m)exist.For non-choking vertical pneumatic conveying system, it is now difficult to classify conveying modes with a Zenz-type phase diagram because of poor understanding of the transition between flow patterns.

关 键 词：气力输送 分类 相图 划分界限 

分 类 号：TH232[机械工程—机械制造及自动化]