The Flow of Aerated Powders State of the Art Review

Publication Reference: 
02-01
Author Last Name: 
Nedderman
Authors: 
Dr. R.M. Nedderman, T. Rathbone
Report Type: 
SAX
Research Area: 
Powder Flow
Publication Year: 
1983
Publication Month: 
05
Country: 
United Kingdom

SUMMARY

The literature on the subject of the flow of aerated powders has been reviewed and is presented in this report under 5 headings.

1. THE FLOW OF COARSE MATERIALS AND THE EFFECT OF INTERSTITIAL PRESSURE GRADIENTS.

It is concluded that the flow of unaerated coarse materials is understood and that correlations and theories exist from which it is possible to predict the discharge rate with precision. The effect of deliberately imposed pressure gradients on the flow of a coarse material is also understood, Some progress has been made in the understanding of the effects of self-generated pressure gradients on the flow of materials of mean size less than 500 um.

CONSOLIDATION. The expulsion of pore water from clays has been well studied in the soil-mechanics literature. of a loosely fitted material has been analysed by Jenike and by Murfitt using similar techniques, methodsare discussed. 5. FLOW OF AERATED POWDER DOWN CHUTES. Only one paper specifically on this topic has been found and this is discussed. T. Rathbone Under the Supervision of Dr. R.M. Nedderman Cambridge November 1983 The case of deaeration

2. FLOODING.

The empirical work of Carr seems to provide a criterion for identifying which materials are liable to flood,though the mechanism of flooding is not understood. Jenike and co-workers maintain that flooding is more likely to occur in core flow hoppers and that materials liable to flood should therefore be stored in mass flow hoppers.

3. THE FLUIDISATION OF FINE POWDERS.

It is concluded that the Geldart classification of powders is the most reliable available for predicting the type of fluidisation that will occur with a given material.

 

4. CONSOLIDATION.

The expulsion of pore water from clays has been well studied in the soil-mechanics literature. The case of dearation of a loosely fitted material has been analysed by Jenike and by Murfitt using similar techniques. The approximations in their methods are discussed.

5. FLOW OF AERATED POWDER DOWN CHUTES.

Only one paper specifically on this topic has been found and this is discussed. T. Rathbone Under the Supervision of Dr. R.M. Nedderman Cambridge November 1983 The case of deaeration