Vacuum assisted flow initiation in arching powders

被引:8
作者
Baserinia, R. [1 ]
Sinka, I. C. [1 ]
Rajniak, P. [2 ]
机构
[1] Univ Leicester, Dept Engn, Leicester LE1 7RH, Leics, England
[2] Res Ctr Pharmaceut Engn RCPE GmbH, Graz, Austria
关键词
Critical orifice; Vacuum; Flow initiation; Model; DIE FILL; GRANULAR SOLIDS; PARTICLE-SIZE; HOPPERS; ORIFICES; SHAPE;
D O I
10.1016/j.powtec.2016.03.051
中图分类号
TQ [化学工业];
学科分类号
0817 ;
摘要
The discharge of powders from hoppers usually takes place in open atmosphere. However, in powder pressing industries (e.g. manufacturing of pharmaceutical tablets, detergents, ceramics, powder metallurgy etc.) there are handling operations where powders are filled into closed cavities such as dies. During this process the air pressure is increased as powder is delivered into the die. At the same time typical tablet production equipment creates a suction effect. A critical orifice measurement apparatus was developed to study powder flow initiation from an arching state into an enclosure where the air pressure is reduced. It was shown that a very small reduction of pressure changed the critical orifice diameter significantly. Dimensional analysis was carried out to relate powder properties (particle size and density) and processing parameters (geometry of the system and differential pressure necessary to break the arch). A relationship was developed to calculate the pressure difference necessary to initiate powder flow. The relationship has two empirical parameters which are calibrated by performing simple experiments using the testing rig developed. (C) 2016 Published by Elsevier B.V.
引用
收藏
页码:493 / 502
页数:10
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