What You Need to Know to Reliably Handle Waste Coal

2003 ◽  
Author(s):  
Roderick J. Hossfeld ◽  
David A. Craig ◽  
Roger A. Barnum
Keyword(s):  
Mass Flow ◽  
Systematic Approach ◽  
Flow Patterns ◽  
Handling System ◽  
Flow Problems ◽  
Energy Facility ◽  
Anthracite Culm ◽  
Funnel Flow ◽  
Major Consideration ◽  
Waste Coal

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.

Aeration Apparatus Converts Bin From Funnel-Flow to Mass-Flow Characteristics

1973 ◽  
Vol 95 (1) ◽  
pp. 37-41 ◽  
Author(s):  
R. B. Emery
Keyword(s):  
Flow Control ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Storage Space ◽  
Flow Problems ◽  
Fine Powders ◽  
Bulk Solid ◽  
Discharge Rates ◽  
Funnel Flow

A properly designed hopper provides cost control through increased unloading reliability, improved storage space utilization, steadier discharge rates, and improved blending of discharged materials. Hoppers have been designed to provide these advantages by providing mass-flow characteristics without application of auxiliary flow promoting devices. Many hoppers are not designed for proper flow. In some cases, limitations on head room, flow rate requirements, or bulk solid characteristics present barriers to design goals of proper flow. Application of aeration can alleviate flow problems in existing hoppers without major changes in hopper configuration and, in addition, it can be helpful in reducing required head room, promoting flow control, and handling some very fine powders. An application of such an aerating device to improve the flow characteristics of fine powders from funnel-flow to mass-flow is discussed in this paper.

Using Flow Properties to Solve Flow Problems with Hard-to-Handle Powders in the Ceramics Industry

2008 ◽  
Vol 591-593 ◽  
pp. 620-627
Author(s):  
Herman Purutyan ◽  
Alfredo del Campo ◽  
Roger A. Barnum
Keyword(s):  
Titanium Dioxide ◽  
Cohesive Strength ◽  
Particle Sizes ◽  
Flow Properties ◽  
Handling System ◽  
Flow Problems ◽  
Fine Powders ◽  
Common Problems ◽  
Ceramic Manufacturing ◽  
Ceramics Industry

Many processes in ceramic manufacturing require handling of fine powders with particle sizes down to sub-micron range. Problems that are often experienced with these powders, such as stoppages and/or surges, can be predicted and prevented by first measuring relevant flow properties of these powders, and then using these properties to design a handling system. In this paper we will review common problems with handling such powders and the relevant flow properties tests, such as permeability, compressibility, cohesive strength and friction, as well as how these properties can be used to prevent and solve problems. Issues related to handling titanium dioxide (TiO2) will be used as an illustration.

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

2000 ◽  
Vol 214 (1) ◽  
pp. 53-62 ◽  
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.

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

2005 ◽  
Vol 219 (4) ◽  
pp. 367-374 ◽  
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.

Flow Patterns and Wall Stresses in a Mass-Flow Bunker

1973 ◽  
Vol 95 (1) ◽  
pp. 17-26 ◽  
Author(s):  
P. M. Blair-Fish ◽  
P. L. Bransby
Keyword(s):  
Mass Flow ◽  
Small Mass ◽  
Flow Patterns ◽  
Normal Stresses ◽  
Flowing Material ◽  
Intense Deformation

Observations are reported of the shear and normal stresses on the walls of a small mass flow bunker and of the variations of density in the flowing material. Changes in wall stresses which occur as the material discharges are correlated with the formation and reformation of zones of intense deformation within the bunker.

scholarly journals Cooling Air Flow in a Multi Disc Industrial Gas Turbine Rotor

1998 ◽  
Author(s):  
D. Brillert ◽  
A. W. Reichert ◽  
H. Simon
Keyword(s):  
Simple Model ◽  
Gas Turbine ◽  
Boundary Layers ◽  
Mass Flow ◽  
Radial Flow ◽  
Flow Patterns ◽  
Navier Stokes ◽  
Mean Flow ◽  
Flow Through ◽  
Secondary Air

The objective of this paper is to investigate the secondary air system in a multidisc rotor. The investigation was performed using Navier-Stokes calculations, network modeling and measurements taking into account new test data from Siemens’ Model V84.3A gas turbine prototype. The objective of the investigation was to better the understanding of flow patterns and to generate a simple model for describing mean flow values. The flow patterns predicted on the basis of Navier-Stokes calculations are described and the losses associated with fluid flow through rotating cavities of multidisc rotors are evaluated. High losses are generated in the radial flow through the corotating discs, and this investigation therefore concentrates on this flow. The investigated mass flowrates are relatively high when compared with the mass flow naturally transported on rotating discs (Cw > 105). One part of the mass flow is forced to flow along the boundary layers. The other part is transported outside of the boundary layers like a free potentially inviscid flow. On the basis of the investigation of the Navier Stokes-calculations, a simple analytical model of the radial flow through the corotating discs is developed. Good agreement was found to exist between the experimental data and the results of the simple model.

Bunker Design—Part 3: Wall Pressures and Flow Patterns in Funnel Flow

1977 ◽  
Vol 99 (4) ◽  
pp. 819-823 ◽  
Author(s):  
D. C. Van Zanten ◽  
P. C. Richards ◽  
A. Mooij
Keyword(s):  
High Pressures ◽  
Flow Patterns ◽  
Funnel Flow

A maximum of four zones have been found to exist within a funnel flow bunker. The wall pressures depend upon whether or not material is flowing along the wall. High pressures were found just above irregularities.

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

1977 ◽  
Vol 99 (4) ◽  
pp. 809-813 ◽  
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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