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.

Real-time solid flow velocity measurement based on a microwave sensor

2018 ◽  
Vol 41 (10) ◽  
pp. 2699-2707
Author(s):  
Jing Zou ◽  
Haigang Wang ◽  
Chengguo Liu ◽  
Daping He ◽  
Zhi Peng Wu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Velocity Measurement ◽  
Solid Particles ◽  
Wall Friction ◽  
Scale Production ◽  
Solid Flow ◽  
Bulk Solid ◽  
Microwave Sensor

Measurement and control of bulk solid flows become increasingly important in industries, such as large-scale production, coal transportation and food processing, although rapid and accurate velocity measurement is still a challenging task in these applications. This paper presents a new velocity measurement method based on a microwave sensor operated at 10.525 GHz and investigates the factors that affect velocity of bulk solid flows and the velocity of the solid particles in order to quantify the flow and improve the efficiency of transportation. In this method, a microwave Doppler Signal Analyser is adopted to calculate the average velocity of bulk solid flows and obtain the instantaneous velocity of a single solid flow. The influence of air friction, pipe collision and particle interactions is also analysed with experiments. The measurement results show that the average velocities of bulk solid flows range from 0.6 to 1.6 m/s, and the interaction between solids play a major effect on solid movements. The effect of pipe wall friction should also be considered. Besides, the mass flow rate and the total mass of bulk solid flow can be calculated. The mass flow rate ranges from 0 kg/s to 0.21 kg/s in the entire experiment.

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.

Flow of Dry Bulk Solids on Bin Walls

1969 ◽  
Vol 91 (2) ◽  
pp. 489-492 ◽  
Author(s):  
P. L. Bernache
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Case Studies ◽  
Mass Flow ◽  
Smooth Wall ◽  
Steel Mill ◽  
Bulk Solids ◽  
Angle Of Friction

The assumption that a smooth wall finish, such as stainless-steel mill finish as opposed to carbon steel, will give mass flow in a less steep cone is not always valid. This paper presents case studies of how the kinematic angle of friction (φ′) between dry bulk solids and bin walls affects the design of mass flow hoppers and how it varies for different materials.

scholarly journals Robust low friction performance of graphene sheets embedded carbon films coated orthodontic stainless steel archwires

Friction ◽  
2021 ◽  
Author(s):  
Zonglin Pan ◽  
Qinzhao Zhou ◽  
Pengfei Wang ◽  
Dongfeng Diao
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Orthodontic Treatment ◽  
Artificial Saliva ◽  
Carbon Film ◽  
Carbon Films ◽  
Graphene Sheets ◽  
Substrate Bias ◽  
Low Friction ◽  
Substrate Bias Voltage

AbstractReducing the friction force between the commercial archwire and bracket during the orthodontic treatment in general dental practice has attracted worldwide interest. An investigation on the friction and wear behaviors of the uncoated and carbon film coated stainless steel archwires running against stainless steel brackets was systematically conducted. The carbon films were prepared at substrate bias voltages from +5 to +50 V using an electron cyclotron resonance plasma sputtering system. With increasing substrate bias voltage, local microstructures of the carbon films evolved from amorphous carbon to graphene nanocrystallites. Both static and stable friction coefficients of the archwire-bracket contacts sliding in dry and wet (artificial saliva) conditions decreased with the deposition of carbon films on the archwires. Low friction coefficient of 0.12 was achieved in artificial saliva environment for the graphene sheets embedded carbon (GSEC) film coated archwire. Deterioration of the friction behavior of the GSEC film coated archwire occurred after immersion of the archwire in artificial saliva solution for different periods before friction test. However, moderate friction coefficient of less than 0.30 sustained after 30 days immersion periods. The low friction mechanism is clarified to be the formation of salivary adsorbed layer and graphene sheets containing tribofilm on the contact interfaces. The robust low friction and low wear performances of the GSEC film coated archwires make them good candidates for clinical orthodontic treatment applications.

scholarly journals Characterisation of UHMWPE Polymer Powder for Laser Sintering

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3496 ◽  
Author(s):  
Yas Khalil ◽  
Neil Hopkinson ◽  
Adam Kowalski ◽  
John Patrick Anthony Fairclough
Keyword(s):  
Flow Characteristics ◽  
Laser Sintering ◽  
Polymer Chains ◽  
Low Friction ◽  
Artificial Joints ◽  
Suitable Material ◽  
Powder Properties ◽  
Sintering Behaviour ◽  
Ultra High Molecular Weight ◽  
Very High

Ultra-high molecular weight polyethylene (UHMWPE) is a thermoplastic semicrystalline polymer that has outstanding mechanical properties, low friction coefficient, excellent wear resistance, and is highly resistant to corrosive chemicals. UHMWPE is found in many applications including artificial joints and filtration. However, UHMWPE parts cannot be produced easily by traditional techniques, such as injection moulding and extrusion because of its very high melt viscosity owing to the extremely long polymer chains. Few attempts were made to process UHMWPE by additive manufacturing, particularly laser sintering. This is due to the lack of understanding of the powder properties of UHMWPE. Therefore, the aim of the powder characterisation process in this study is to gain a better understanding of the material requirements and provide a detailed insight on whether UHMWPE is a suitable material for laser sintering. The characterisation process includes powder morphological and flow characteristics, thermal behaviour and stability, and crystallinity of UHMWPE. The study reveals that the sintering behaviour of polymers is controlled by the morphology of the particles in addition to the viscous flow of UHMWPE. There are still difficulties of processing UHMWPE due to highly agglomerated structure of smaller particles with the presence of fibrils in the UHMWPE particles.

Is Ultra-Low Friction Needed to Prevent Wear of Diamond-Like Carbon (DLC)? An Alcohol Vapor Lubrication Study for Stainless Steel/DLC Interface

2011 ◽  
Vol 42 (3) ◽  
pp. 285-291 ◽  
Author(s):  
Matthew J. Marino ◽  
Erik Hsiao ◽  
Laura C. Bradley ◽  
Osman L. Eryilmaz ◽  
Ali Erdemir ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Diamond Like Carbon ◽  
Low Friction ◽  
Alcohol Vapor ◽  
Vapor Lubrication

Tribological Behavior of Ion Implanted AISI 440C Stainless Steel under Oil Lubricated Condition

2013 ◽  
Vol 419 ◽  
pp. 334-340 ◽  
Author(s):  
Feng Bin Liu ◽  
Hui Ping Li ◽  
Yan Cui ◽  
Jie Jian Di ◽  
Min Qu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Tribological Behavior ◽  
Three Dimensional ◽  
Sample Surface ◽  
Surface Structures ◽  
Low Friction ◽  
Effect Mechanism ◽  
Nitrogen Ion ◽  
N Compounds ◽  
Ion Implanted

The tribological behaviors of nitrogen and titanium ion implanted AISI 440C stainless steel were studied by using an oscillating ball-on-disk tribometer under oil lubricated condition. The results showed that the ion implantations would significantly decrease the friction coefficient of the samples. To interpret the effect mechanism of the ion implantation on tribological performance, the surface morphology and oil wettability of the ion implanted samples were investigated by using a three-dimensional white interferometer and a contact angle analyzer, respectively. In addition, the surface structures and components of the samples were analyzed by using XRD and XPS techniques. The results indicated that the low friction coefficients of the ion implanted samples can be attributed to the new phases formed on the sample surfaces. For nitrogen ion implanted sample, the metal nitrides, supersaturated interstitial N and some C-O-N compounds appear on the sample surface. For titanium ion implanted sample, apart from TiO2and TiC phases form at the AISI 440C steel surface. Those components increase the surface energy of the AISI 440C steel and are in favor of the formation of the thin oil film.

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.

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