scholarly journals Concentration distribution and deposition limit of medium-coarse sand-water slurry in inclined pipe

2020 ◽  
Vol 68 (1) ◽  
pp. 83-91
Author(s):  
Pavel Vlasák ◽  
Václav Matoušek ◽  
Zdeněk Chára ◽  
Jan Krupička ◽  
Jiří Konfršt ◽  
...  
Keyword(s):  
Inclination Angle ◽  
Concentration Distribution ◽  
Silica Sand ◽  
Narrow Particle Size Distribution ◽  
Mean Velocity ◽  
Horizontal Pipe ◽  
Slurry Concentration ◽  
Limit Velocity ◽  
Water Slurry ◽  
Pipe Inclination

AbstractSand-water slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal, inclined, and vertical smooth pipe sections. A narrow particle size distribution silica sand of mean diameter 0.87 mm was used. The experimental investigation focused on the effects of pipe inclination, overall slurry concentration, and mean velocity on concentration distribution and deposition limit velocity. The measured concentration profiles showed different degrees of stratification for the positive and negative pipe inclinations. The degree of stratification depended on the pipe inclination and on overall slurry concentration and velocity. The ascending flow was less stratified than the corresponding descending flow, the difference increasing from horizontal flow up to an inclination angle of about +30°. The deposition limit velocity was sensitive to the pipe inclination, reaching higher values in the ascending than in the horizontal pipe. The maximum deposition limit value was reached for an inclination angle of about +25°, and the limit remained practically constant in value, about 1.25 times higher than that in the horizontal pipe. Conversely, in the descending pipe, the deposition limit decreased significantly with the negative slopes and tended to be zero for an inclination angle of about −30°, where no stationary bed was observed.

scholarly journals Effect of pipe inclination on flow behaviour of fine-grained settling slurry

2019 ◽  
Vol 213 ◽  
pp. 02094
Author(s):  
Pavel Vlasak ◽  
Zdenek Chara ◽  
Vaclav Matousek ◽  
Jiri Konfrst ◽  
Mikolas Kesely
Keyword(s):  
Concentration Distribution ◽  
Gamma Ray ◽  
Deposition Velocity ◽  
Narrow Particle Size Distribution ◽  
Local Concentration ◽  
Horizontal Pipe ◽  
Pressure Drops ◽  
Fine Grained ◽  
Inclined Pipe ◽  
Pipe Inclination

The effect of flow parameters of fine-grained settling slurry on the pressure drop-velocity relationship, deposition limit velocity and local concentration distribution was studied in an experimental pipe loop of inner diameter D = 100 mm with inclinable pipe sections for pipe inclination ranging from – 45° to +45°. The slurry consisted from water and narrow particle size distribution glass beads of mean diameter d50 = 0.18 mm. The concentration distribution was studied with application of a gamma-ray densitometry. The deposition velocity was defined as the flow velocity at which stationary deposit started to be formed at the pipe invert. The study revealed the stratified flow pattern of the studied slurry in inclined pipe sections, for slurry velocities below to the deposition limit sliding or stationary bed were created in ascending pipe sections. For low pipe inclination (α < ± 25°) the effect of inclination on local concentration distribution was not significant. Mean transport concentration for descending flow was lower than that for the ascending flow Deposition limit in inclined pipe was slightly lower than that in horizontal pipe. Frictional pressure drops in ascending pipe were higher than that in descending pipe, the difference decreased with increasing velocity and inclination.

Effect of Pipe Inclination on Solids Distribution in Partially Stratified Slurry Flow

2019 ◽  
Author(s):  
Václav Matoušek ◽  
Jan Krupička ◽  
Jiří Konfršt ◽  
Pavel Vlasák
Keyword(s):  
Uniform Distribution ◽  
Cross Section ◽  
Inclination Angle ◽  
Concentration Profile ◽  
Stratified Flow ◽  
Concentration Profiles ◽  
Horizontal Pipe ◽  
Pipe Cross Section ◽  
Test Loop ◽  
Pipe Inclination

Abstract Partially stratified flows like flows of sand-water slurries exhibit non-uniform distribution of solids (expressed as a vertical profile of local volumetric concentration) in a pipe cross section. The solids distribution in such flows is sensitive to pipe inclination. The more stratified the flow is the more sensitive its concentration profile is to the pipe slope. In general, the distribution tends to become more uniform (less stratified) if the inclination angle increases from zero (horizontal pipe) to positive values (ascending pipe) up to 90 degree (vertical pipe). In a pipe inclined to negative angles (descending pipe) the development is different. The flow tends to stratify more if it changes from horizontal flow to descending flow down to the angle of about −35 degree. If the angle further decreases towards −90 degree, then the flow becomes less stratified reaching uniform distribution at the vertical position. This also means that the same flow exhibits a very different degree of stratification in ascending and descending pipes inclined to the same (mild) slope say between ±10 and ±40 degree. The rather complex development of the solids distribution with the variation of the inclination of pipe is insufficiently documented experimentally and described theoretically in predictive models for a concentration profile in partially stratified flow. In order to extend the existing limited data set with experimental data for partially stratified flow of medium sand slurry, we have carried out a laboratory experiment with the slurry of narrow graded fraction of sand with the mean grain size of 0.55 mm in our test loop with an invert U-tube inclinable to arbitrary angle between 0 and 90 degree. A pipe of the loop has an internal diameter of 100 mm. Both legs of the U-tube have a measuring section over which differential pressures are measured. Radiometric devices mounted to both measuring sections sense concentration profiles across a pipe cross section. Furthermore, the discharge of slurry is measured in the test loop. In the paper, experimental results are presented for various inclination angles with a small step between 0 and ±45 degree and a development in the shape of the concentration profiles with the changing inclination angle is analyzed. For the analysis, it is critical to distinguish between suspended load and contact load in the flow as the two loads tend to react differently to the flow inclination. The measured concentration profiles and pressure drops are compared with predictions by the layered model adapted for taking the flow inclination into account.

scholarly journals Experimental investigation of fine-grained settling slurry flow behaviour in inclined pipe sections

2019 ◽  
Vol 67 (2) ◽  
pp. 113-120
Author(s):  
Pavel Vlasák ◽  
Zdeněk Chára ◽  
Václav Matoušek ◽  
Jiří Konfršt ◽  
Mikoláš Kesely
Keyword(s):  
Concentration Distribution ◽  
Flow Behaviour ◽  
Narrow Particle Size Distribution ◽  
Local Concentration ◽  
Slurry Flow ◽  
Pressure Drops ◽  
Fine Grained ◽  
Limit Velocity ◽  
The Difference ◽  
Inclined Pipe

Abstract For the safe and economical design and operation of freight pipelines it is necessary to know slurry flow behaviour in inclined pipe sections, which often form significant part of pipelines transporting solids. Fine-grained settling slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal and inclined pipe sections for pipe slopes ranging from −45° to +45°. The slurry consisted of water and glass beads with a narrow particle size distribution and mean diameter d50 = 180 µm. The effect of pipe inclination, mean transport volumetric concentration, and slurry velocity on flow behaviour, pressure drops, deposition limit velocity, and concentration distribution was studied. The study revealed a stratified flow pattern of the studied slurry in inclined pipe sections. Frictional pressure drops in the ascending pipe were higher than that in the descending pipe, the difference decreased with increasing velocity and inclination. For inclination less than about 25° the effect of pipe inclinations on deposition limit velocity and local concentration distribution was not significant. For descending pipe section with inclinations over −25° no bed deposit was observed.

scholarly journals Experimental and Numerical analysis of Flow characteristics of sand water slurry in a horizontal pipe

2021 ◽  
Author(s):  
Varinder Singh ◽  
◽  
Satish Kumar ◽  
Dwarikanath Ratha ◽  
◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Pressure Loss ◽  
Volume Fraction ◽  
Head Loss ◽  
Experimental Results ◽  
Solid Concentration ◽  
Horizontal Pipe ◽  
Slurry Concentration ◽  
Water Slurry ◽  
Test Loop

The transportation of the solid material using hydraulic transportation method is economically the best method. The head loss occurs during transportation of slurry through horizontal pipelines usually depends on the rheological behavior of slurry, slurry concentration, particle size, and influx velocity. An experimental investigation has been performed using sand-water slurry flowing through the horizontal pipe section of a pilot plant test loop. The head loss obtained from the experimental results was validated through CFD simulation using FLUENT. The solid concentration of sand-water slurry and influx velocity used during both experiments and numerical simulation were in the range of 10-40% (by weight) and 1 to 4 m/s respectively. The numerical simulations were performed using five different turbulence models and the results obtained using SST k-omega model was in close agreement with experimental results. It is observed from both the experiment and numerical analysis that the pressure loss, granular pressure, volume fraction and skin fraction coefficient during transportation of slurry through a horizontal pipe is a function of solid concentration and influx velocity. The present study observed that as the flow velocity increases four times, the pressure loss is increasing more than 10 times. Uniform volume fraction at middle zone of outlet of the pipe is observed as both the slurry concentration and velocity of flow increases.

scholarly journals Numerical Analysis of Convective Transport of Fly Ash-Water Slurry through a Horizontal Pipe

2015 ◽  
Vol 7 (2) ◽  
pp. 79-96 ◽  
Author(s):  
Bibhuti Bhusan Nayak ◽  
Satish Kumar Gupta ◽  
Dipankar Chatterjee ◽  
Amar Nath Mullick
Keyword(s):  
Fly Ash ◽  
Numerical Analysis ◽  
Convective Transport ◽  
Horizontal Pipe ◽  
Water Slurry

Effect of Inclination Pipe Angle on Oil-Water Two Phase Flow Patterns and Pressure Loss

2014 ◽  
Author(s):  
S. Alireza Hojati ◽  
Pedram Hanafizadeh
Keyword(s):  
Water Flow ◽  
Inclination Angle ◽  
Pressure Loss ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Inclination Angles ◽  
Oil Water ◽  
Pipe Inclination

The flow patterns in two phase and multi-phase flows is a significant factor which influences many other parameters such as drag force, drag coefficient and pressure drop in pipe lines. One of the major streams in the gas and oil industries is oil-water two phase flow. The main flow patterns in oil-water flows are bubbly, slug, dual continuous, stratified and annular. In the present work flow patterns in two phase oil-water flow were investigated in a 0.5in diameter pipe with length of 2m. 3D simulation was used for this pipe and six types of mesh grid were used to investigate mesh independency of the simulation. The proposed numerical analyses were performed by a CFD package which is based both on volume of fluid (VOF) and Eulerian-Eulerian methods. The results showed that some flow patterns can be simulated better with VOF method and some other maybe in Eulerian-Eulerian method, so these two methods were compared with together for all flow patterns. The flow patterns may be a function of many parameters in flow. One of the important parameter which may affect flow patterns in pipe line is pipe inclination angle; therefore flow patterns in the different pipe inclination angles were investigated in two phase oil-water flow. The range of inclinations has been varied between −45 to +45 degree about the horizon. In the presented simulation oil is mixed with water via a circular hole at center of the pipe, the ratio of oil surface to water surface at entrance is 2/3 so water phase was considered as the main phase. Flow patterns were investigated for every angle of pipe and numerical results were compared with available experimental data for verification. Also the flow patterns simulated by numerical approaches were compared with available flow regime maps in the previous literatures. Finally, effect of pipe inclination angle and flow patterns on the pressure loss were investigated comprehensively.

scholarly journals Effect of a Symmetric Contraction on the Concentration Profiles of a Particle-Laden Slurry

2011 ◽  
Author(s):  
A. Deshpande ◽  
K. Ramisetty ◽  
F. W. Chambers ◽  
M. E. McNally ◽  
R. M. Hoffman
Keyword(s):  
Single Phase ◽  
Solid Phase ◽  
Fluid Dynamic ◽  
Density Ratio ◽  
Primary Phase ◽  
Solid Particles ◽  
Concentration Profiles ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Slurry Concentration

In-line measurements and sample stream withdrawals for on-line and/or at-line measurements of slurries flowing in horizontal pipes can be complicated by nonuniform slurry profiles. More uniform profiles would improve measurements. Area contractions are a common means used to produce more uniform velocity fields for single phase flows. For example, contractions are used to condition the flow entering wind tunnel test sections and make velocity profiles more uniform at venturi throats. It was desired to determine whether area contractions could be used to make slurry concentration profiles more uniform in horizontal pipe flows. An ASME flow nozzle with a contraction diameter ratio of 0.5 was chosen as a well defined geometry to consider in a Computational Fluid Dynamic (CFD) study of the effects of a contraction on slurry concentration profiles. The pipe was 2.8 m long with a 50.8 mm diameter. The entrance of the contraction was placed at 35 pipe diameters from the inlet in fully developed flow. A length of 20 diameters followed the contraction. The slurry had a xylene liquid phase and an ADP solid phase with a density ratio of 1.7. The simulations were performed at primary phase velocities of 2 m/s and 4 m/s, corresponding to Reynolds numbers of 1.4E05 and 2.8E05. Spherical particle diameters of 38, 75, and 150 μm were used at concentrations of 0.05, 0.2, and 0.3. ANSYS FLUENT 12 software was used with the standard k-ε turbulence model and standard wall function. The mixture multi-phase model was used for the two-phase flow. An unstructured tetrahedral meshing scheme was used with 1.4 million elements. The grid was adjusted until the condition 30 < y+ <60 for the mesh point nearest the wall was satisfied. A grid refinement study was performed to insure grid independence. The computational scheme first was validated by comparing pipe flow velocity and concentration profiles to results in the literature. The computations performed with the contraction showed that in all cases the concentration profiles of the solid particles displayed greater uniformity than the profiles in the pipe upstream of the contraction. The effect of the contraction was more pronounced for the larger particles. As in the case of single phase flows, the contraction caused the axial turbulence intensity to decrease. The greater uniformity of the concentration profiles at the exit plane of the nozzle, suggest that the contraction can provide better conditions for performing measurements of a particle-laden slurry.

The mean velocity of slightly buoyant and heavy particles in turbulent flow in a pipe

1958 ◽  
Vol 4 (1) ◽  
pp. 87-96 ◽  
Author(s):  
A. M. Binnie ◽  
O. M. Phillips
Keyword(s):  
Turbulent Flow ◽  
Relative Density ◽  
Terminal Velocity ◽  
Neutral Density ◽  
Mean Velocity ◽  
Heavy Particles ◽  
Horizontal Pipe ◽  
The Mean ◽  
The Times

A large number of small spheres of the same size were injected successively into a horizontal pipe conveying water at constant mean velocity, and their times of transit were measured. The mean velocity of the spheres that were either somewhat heavier or lighter than water was less than that of those of neutral density; for those having a terminal velocity in water within ± 1% of the mean velocity of the water in the pipe, the discrepancy was only about 0.1%. The dispersion of the times of transit of the spheres was almost independent of their density. A theory is developed to show how the mean velocity of the spheres depends upon their relative density and size.

scholarly journals Counter Current Flow Limitation of Gas-Liquid Two-Phase Flow in Nearly Horizontal Pipe

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Sigit Prayitno ◽  
R. A. Santoso ◽  
Deendarlianto ◽  
Thomas Höhne ◽  
Dirk Lucas
Keyword(s):  
Inclination Angle ◽  
Current Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Limitation ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Air Inlet ◽  
Inner Diameter ◽  
Counter Current

Experimental work about counter current two-phase flow of air and gas in nearly horizontal pipe has been performed. The work was performed in a 1.1 m long circular transparent acrylic pipe with 50 mm inner diameter, in two inclination angle settings (20° and 10° from horizontal). The smooth liquid and air inlet was used. Porous liquid inlet and a nozzle connected with calm section were used as liquid and gas inlet. The effect of liquid properties is examined by using five different working fluids (Water, two different concentration of butanol and glycerin aqua solutions). As for results. (1) CCFL causes a drastic change in the delivered liquid to the lower plenum. (2) The effect of inclination angle is significantly observed. The flooding gas superficial velocity decreases with inclination angle. (3) The liquid viscosity affects the flooding phenomena.

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