Investigation on Flow Patterns and Transitions in a Multiple-Spouted Bed
Investigation on Flow Patterns and Transitions in a Multiple-Spouted Bed
复制标题
多喷动床中流动模式和转变的研究
DOI：
10.1021/ef901449m
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发表时间：
2010-03-01
期刊：
影响因子：
5.3
通讯作者：
Xiao, Rui
中科院分区：
文献类型：
--
作者：
Ren, Bing;Zhong, Wenqi;Xiao, Rui
在可见多喷动床中进行了流动形态和转变的实验研究。该床由3个截面为100 × 30 mm的喷动床单元组合而成，每个单元都有一个宽度为10 mm的独立喷动喷嘴。采用密度为900 kg/m3、平均粒径为2.8 mm的聚丙烯珠粒作为床层材料。六种不同的流动模式，即，固定床（FB）、内喷射（IJ）、内喷射气泡（IJB）、单喷动（SS）、多喷动（MS）和内喷射段塞流（IJS）等6种流型。绘制了三个静态床层高度的典型流型图，描述了中心喷动气体和辅助喷动气体的流型转变。此外，一些重要的流动特性与流动模式和过渡，即，最小喷动速度和压降。结果表明，流态的类型取决于静止床层高度，特别是IJS的流态只在静止床层高度较高时才出现。中心最小喷动速度随静止床层高度的增加而增加，随辅助喷动气流量的减小而减小，随辅助喷动气流量的增大而增大。当中心喷动气流量一定时，总压降随辅助喷动气流量的增加先增大后减小;当中心喷动气流量一定时，总压降随辅助喷动气流量的增加先增大后显著减小。
Experimental studies on flow patterns and transitions were carried out in a visible multiple-spouted bed. The bed combines three spouted bed cells, each with a cross-section of 100 × 30 mm, and each cell has an independent spout nozzle of 10 mm in width. Polypropylene beads with a density of 900 kg/m3and mean diameter of 2.8 mm were used as bed materials. Six distinct flow patterns, i.e., fixed bed (FB), internal jet (IJ), internal jet with bubble (IJB), single spouting (SS), multi-spouting (MS), and internal jet with slugging (IJS), were determined on the basis of criteria as well as schematic diagrams and typical flow pattern images obtained from a high-resolution digital charge coupled device (CCD) camera. Typical flow regime maps at three static bed heights were plotted to describe the transitions of flow patterns with central and auxiliary spouting gases. Besides, some important flow characteristics associated with flow patterns and transitions, i.e., minimum spouted velocity and pressure drop, were studied. The results showed that the kind of flow pattern was dependent upon the static bed height; in particular, the flow pattern of IJS was only found at a high static bed height. The central minimum spouting velocity increased with an increasing static bed height, decreased with a low auxiliary spouting gas flow rate, but increased with a high auxiliary spouting gas flow rate. The total pressure drop increased first and then decreased gradually with the auxiliary spouting gas at a certain central spouting gas flow rate, while it increased first and then remarkably decreased with the central spouting gas at a given auxiliary spouting gas flow rate.