Bin Loads—Part 4: Funnel-Flow Bins

Many power producers have been designing for, or switching to waste coal. A major consideration when dealing with waste coal is the design of the fuel handling system. Since waste coal is typically finer and more cohesive and therefore harder to handle in silos, bunkers, chutes and feeders, design of the handling system for reliable, non-stagnant flow is essential. This paper describes a systematic approach to designing and retrofitting handling systems to avoid bulk solids flow problems. Potential trouble areas such as coal hoppers, silos, bunkers, and transfer chutes are discussed. Mass flow and funnel flow patterns that develop in silos and bunkers are presented. Funnel flow results in large stagnant regions, which are a major problem for coals that combust easily and are prone to problems such as arching and ratholing. Mass flow patterns, which eliminate the stagnant coal regions, are also explained. Coal properties and bunker designs that result in mass flow and funnel flow are described. Transfer chute design techniques to avoid pluggages, reduce dusting, and minimize chute wear are discussed. The Panther Creek Energy facility in Nesquehoning, Pennsylvania is used as an example where solids flow handling methodologies were used to solve handling problems with anthracite culm. The modifications presented were required for reliable, stagnant-free coal flow, which prevented belt slippage and high belt loading on gravimetric feeders.

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Effects of the properties of bulk solids on the relative performance of polyethylene and stainless steel wall lining materials in mass flow hoppers and other applications

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1243/0954408001530218 ◽

2000 ◽

Vol 214 (1) ◽

pp. 53-62 ◽

Cited By ~ 3

Author(s):

M S A Bradley ◽

M Bingley ◽

R J Farnish ◽

A N Pittman ◽

G Lee

Keyword(s):

Stainless Steel ◽

Mass Flow ◽

Wall Friction ◽

Friction Test ◽

Low Friction ◽

Flow Discharge ◽

Flow Problems ◽

Bulk Solids ◽

Bulk Solid ◽

Ultra High Molecular Weight

Reducing the friction between the walls of storage vessels and the bulk solids that they contain is widely known to be beneficial in obtaining more satisfactory flow patterns in such vessels, and to reduce flow problems. In particular, the advantages of low friction in promoting a mass flow discharge pattern are well understood; means of obtaining data to design a hopper for mass flow are also well established. In recent years a number of polyethylene materials have come on to the market, intended for use in lining silos and claimed by their manufacturers to offer low wall friction in comparison with other materials. In this paper, one particular commercial grade of ultra-high molecular weight polyethylene (UHMWPE) material has been tested alongside a commonly used type and finish of ferritic stainless steel. The wall friction has been measured for both materials, with a variety of bulk solid materials and conditions, and the hopper half-angles needed for mass flow computed for each combination. The results show that the UHMWPE material does not always offer a lower friction than the stainless steel; in some cases it offers much lower friction and hence much greater scope for obtaining mass flow discharge. However, in other cases it gives significantly higher friction and is a bad choice for promoting flow. The principal conclusion is that, under certain circumstances, UHMWPE offers substantial advantages over other wall materials. However, this advantage is by no means universal and, if it is to be considered for employment in a hopper design, then a wall friction test should be undertaken. This test should use a sample of the bulk solid to be handled against both the UHMWPE material and other possible materials.

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Innovative design to enhance solids discharge from conical bottom ion-exchange columns. Part 1

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1243/095440805x33153 ◽

2005 ◽

Vol 219 (4) ◽

pp. 367-374 ◽

Cited By ~ 1

Author(s):

M Daas ◽

A. V. Retnaswamy ◽

R Srivastava

Keyword(s):

Particle Size ◽

Flow Pattern ◽

Discharge Rate ◽

Innovative Design ◽

Flow Problems ◽

Bulk Solids ◽

Wide Range ◽

Problems And Solutions ◽

Funnel Flow ◽

Conical Bottom

An investigation of flow problems and solutions, associated with bulk solids discharging from conical-bottom cylindrical storage containers, is presented in this paper. The feasibility and efficiency of bulk solids discharging from these containers are directly associated with the flow pattern of the solids. The influence of a new vessel design on the flow pattern and the discharge rate of solids was examined. Glass beads of fixed particle size distribution and density were used to conduct the study. Retrofitting techniques that are commonly used to improve the flow pattern characteristics in silos were reviewed. Two techniques, utilization of inserts and hopper in hopper were investigated, and the results from the first technique are discussed. This technique is based on the usage of a double pyramid-shaped insert to manipulate the flow pattern of discharging solids. Both dry and wet tests were conducted under a wide range of low to moderate pressures. The results from both dry and wet tests showed that the pyramid insert was able to significantly change the flow pattern from the undesired funnel flow to the most desired mass flow and also increase the rate of discharge.

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Powder flow criteria for design of vertical silo walls

Engenharia Agrícola ◽

10.1590/s0100-69162013000300003 ◽

2013 ◽

Vol 33 (3) ◽

pp. 453-462 ◽

Cited By ~ 4

Author(s):

José P. Lopes Neto ◽

José W. B. do Nascimento ◽

Rafael C. Silva ◽

Carlos A. da Costa

Keyword(s):

Mass Flow ◽

Reduced Model ◽

Powder Flow ◽

Flow Properties ◽

Bulk Solids ◽

Flow Prediction

For design of vertical silos walls involving the storage of bulk solids to be safe and reliable, it is important knowing the largest possible number of variables such as: flow properties, silo geometry and pattern of flow desired. In order to validate the theories of flow prediction and design of conical hoppers, the flow properties of two bulk solids were determined, the theories of Jenike's flowability and Enstad and Walker for hopper design were analyzed and the results were compared with those experimentally obtained in a reduced model of a semicircular-section silo. Results show that Enstad theory for the hopper design is adequate to occur mass flow inside the silo, and for the sizing of the discharge outlet, the Walker's theory was closer to the appropriate than Jenike's theory, which was higher around 100% than the experimental hopper outlet.

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Mass flow rate measurement of bulk solids based on microwave tomography and microwave Doppler methods

Powder Technology ◽

10.1016/j.powtec.2019.09.087 ◽

2020 ◽

Vol 360 ◽

pp. 112-119

Author(s):

Jing Zou ◽

Chengguo Liu ◽

Haigang Wang ◽

Zhi Peng Wu

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Rate Measurement ◽

Microwave Tomography ◽

Flow Rate Measurement ◽

Bulk Solids

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Study of gate loads related to stress states in mass-flow bins during bulk solids filling and settlement

Advanced Powder Technology ◽

10.1016/j.apt.2021.01.018 ◽

2021 ◽

Vol 32 (3) ◽

pp. 683-692

Author(s):

Alan Roberts ◽

Jiahe Shen ◽

Brendan Beh ◽

Bin Chen ◽

Timothy Donohue

Keyword(s):

Mass Flow ◽

Bulk Solids ◽

Stress States

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Bunker Design—Part 1: Bunker Outlet Design and Initial Measurements of Wall Pressures

Journal of Engineering for Industry ◽

10.1115/1.3439354 ◽

1977 ◽

Vol 99 (4) ◽

pp. 809-813 ◽

Cited By ~ 5

Author(s):

P. C. Richards

Keyword(s):

Flow Pattern ◽

Mass Flow ◽

Design Method ◽

Measuring Technique ◽

Funnel Flow

Experiments have shown that the Jenike bunker outlet design method is accurate with respect to both the flow pattern (mass flow or funnel flow) and the minimum outlet required. Initial measurements of wall pressures in a 0.6-m-dia mass flow bunker were used to select a suitable measuring technique for use in larger scale equipment, which is also described.

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