Slurry Pipeline Research Articles

Identification of viscosity and solid fraction in slurry pipeline transportation based on the inverse heat transfer theory

A method based on the inverse heat transfer theory for identifying the viscosity coefficient and solid volume fraction of slurries is proposed in this study. An inverse heat convection problem for non-Newtonian fluid is solved in a fully developed laminar circular pipe flow based on temperature measurements obtained at several radial locations in the stream. An optimal estimation of the apparent viscosity of slurries is obtained by the relationship between temperature profile and apparent viscosity. The solid volume fraction in the pipe can be eventually determined through the applicable relation between solid loading and viscosity. Several experiments were conducted to verify the accuracy of the method. Coal-water slurry and coal-slime slurry were considered for the validation. Comparisons between the estimated values and experimental data showed that this method was reliable for predicting viscosity coefficient and solid fraction in slurry fluid. It is expected to be useful in detecting the rheological properties for determining operation mode of slurry pipelines.

Determination of the Drag Reduction Mechanism Associated with the Pneumatic Regulation of Slurry Pipeline Transport using a Numerical Method

Determination of the Drag Reduction Mechanism Associated with the Pneumatic Regulation of Slurry Pipeline Transport using a Numerical Method

Study on velocity distribution of large particle in vertical slurry pipeline

Velocity distribution of vertical pipes with large particle slurry plays an important role in pipeline transportation of minerals in hydraulic coal mining and ocean mining industry. The experiments of particle fluidization and particle vertical lift are conducted and the fluidization data of three kinds of large particles are analyzed. The results show that the vortex resistance prevents particles from moving as the coarse particles move in vertical pipes. An additional coefficient method is proposed to study the vortex resistance by increasing the coefficient of vortex resistance before interference. Mathematical model is established to describe the drag coefficient of the vortex by analyzing the influence factors of the experimental data and the drag coefficient of the vortex. In addition, calculation model of the velocity distribution of large particles in vertical pipe is proposed by analyzing the force, the fluid, and the solid momentum. Moreover, the experimental data of particle transport in vertical pipes are utilized to verify and analyze the proposed model.

Method for determining the critical velocity of paste-like slurry filling into goaf using computational fluid dynamics

The coal mining mode of paste-like slurry fill shows the connotation and characteristics of green mining both in the resource recycle and waste reuse. Test by intelligent torque sensor, fitted by the ORIGIN software, the following relationships were obtained: (1) rheological parameters versus slurry mass fraction, (2) rheological parameters versus component ratio. Based on the relationships, the recommended ratio of paste-like slurry was determined. The mass concentration of slurry is no more than 78%, which is composed by coal gangue (diameter < 20 mm), fly ash (diameter < 30 μm), and gelling agent with the weight ratio of 8:3:1. The pipe flow dynamic characteristics of paste-like slurry have been analyzed by computational fluid dynamics (CFD) and CFD-POST. By simulating the flow behavior of the slurry at different velocities under a stable state in the horizontal pipe, the analysis of the paste-like slurry’s non-silting velocity has been done. Combined with the laboratory test data and mechanical models, the different concentrations and the velocities of the paste-like slurry in pipelines under different inlet velocities were introduced. The critical velocity is about 1 m/s corresponding to a pipe diameter of 150 mm. The results provide a better insight into the process of transportation of paste-like slurry, as well as to more cost-effective engineering designs of sustainable development of the environment and coal mines.

Effect of Particle Shape on Pipeline Damage in Liquid-Solid Two-Phase Flow

The shield machine is an indispensable mechanical equipment in the construction of urban rail transit. The mud shield is currently the most commonly used in urban rail transit construction. For the circulation system of the mud-water shield, the damage of the different shapes of the particles to the slurry pipeline was studied. According to the shape of clay, stone and gravel in practice, five different shapes of particle models were established for the sake of simplicity. In order to better study the characteristics of different materials, the particle model was established by discrete element software EDEM, and the mud model was established by fluid software Fluent. The fluid model is then coupled to the particle model in the discrete element. The effect of the movement of the particles in the pipe and the presence of the particles on the flow of the slurry in the pipe is analyzed. The study found that under the same volume, the shape of the particles has little effect on the fluid, but the damage to the pipeline is quite different. Among them, the lower the sphericity, the greater the collision number and energy loss between the particles and the pipeline.

Investigation on flow characteristics of ice slurry in horizontal 90° elbow pipe by a CFD-PBM coupled model

Elbow pipes are important components for ice slurry pipeline transport. However, the flow characteristics of ice slurry in elbow are far from fully being understood, especially the influence of ice particle kinetics on ice particle size distribution (PSD). This study is intended to provide a better understanding of the behavior of ice slurry flow in elbow pipe. A CFD-PBM coupled model is employed to investigate the flow characteristics of ice slurry in horizontal 90° elbow pipe. The quadrature method of moments is utilized to solve the population balance equations. Based on the revised model, the flow characteristics of ice slurry in the horizontal 90° elbow pipe are investigated. The simulation results show that in the range of calculations, the pressure drop of elbow pipe is increased with the increase of velocity and ice packing fraction (IPF). An adverse pressure gradient is formed due to the change in flow direction. The emergence of secondary flow is caused by the centrifugal force. It makes the ice particles gather on the outer wall of the elbow section. The ice diameter increases along the flow direction due to the aggregation. The evolution of particle size distribution (PSD) is not significant. However, aggregation and stratification cannot be ignored in the process of long distance transport of ice slurry. The results are of significance for guiding the safety design and operation of ice slurry transportation.

Physically based modeling, characterization and design of an induction hardening process for a new slurry pipeline steel

Numerical and Gleeble experimental data are combined to predict potential microstructure and hardness profiles through the wall thickness of an induction hardened slurry transportation pipe made of a recently developed 0.4 wt% C, Nb-microalloyed steel. The calculated thermal history of various positions through the wall thickness of an industrial pipe (400 mm diameter, 10 mm thick) were combined with a model that predicts the phase transformations, microstructures and final hardness values on heating and cooling along arbitrary thermal cycles. The accuracy of the hardness profile predictions was verified by experimental data, i.e. reproducing the thermal cycles on a Gleeble thermomechanical simulator. The results indicated that the approach should be a feasible way to optimize induction heating and cooling parameters to obtain desired hardness profiles through the wall thickness.

Analysis of Energy Sustainability in Ore Slurry Pumping Transport Systems

The mining industry is characterized by a high consumption of energy due to the wide diversity of processes involved, specifically the transportation of ore slurry via pipeline systems. This study investigates the relationship among the variables that define the slurry transportation system to minimize the power requirements and increase energy sustainability. The energy indicator (I), the criterion used for the energy assessment of three different pumping system layouts, was computed via numerical simulation. Optimization of response I was carried out through a statistical technique in the design of the experiment. In the study, four variables were defined to describe the slurry transportation systems, two of which are associated with the piping system (length L and diameter D); the other two are related to the slurry pattern (the volumetric concentration Cv and granulometry D50). The results show that all variables are statistically significant relative to the indicator I, with L having the greatest amplitude of variation in the response, increasing the energy indicator by approximately 60%. Likewise, the decrease of the D50 from 300 µm to 100 µm produces an average decrease of I of 24%. Moreover, the interaction among the factors indicates that two pairs of factors are correlated, namely D50 with L and D with L. Finally, a predictive model obtained a fit that satisfactorily relates with the numerical data, allowing, in a preliminary way, to identify the minimum power requirement in iron ore slurry pipeline systems.

In Situ Verification of Numerical Model of Water Hammer in Slurries

This paper presents a numerical model of transient flow in a pressure slurry pipeline network with verification based on in situ measurements. The model, primarily verified in laboratory conditions, has been extended and applied to the case of a large and complex slurry pipeline network in Poland. In the model, the equivalent density concept was applied. In situ experiments were performed for various unsteady flow episodes, caused by different pump operation strategies in the industrial pipeline network. Based on the measurements of slurry concentration and pressure variations, the numerical model was tested and verified. A satisfactory coincidence between the calculated and the observed pressure characteristics was achieved. Additional numerical tests led to important conclusions concerning safe pump and valve operation and system security threats.

Synergistic effect of the addition of TiO2 feedstock on solid particle erosion of Ni/Al2O3 and Ni/Cr2O3 coatings

Pipelines are widely used for transportation of solids in many chemical and mining industries. Erosion wear is considered as one of the important parameters which play a significant role in slurry transportation system by affecting both initial cost and life of slurry pipelines. Erosion wear of pipeline is not only important from the design aspect but also from the equipment performance, reliability and operational durability. In the present work, erosion wear due to solid-liquid mixture has been investigated using a slurry erosion pot tester. The erosion tests have been conducted on pipeline material Mild steel (M.S.) to establish the influence of rotational speed, particle size, solid concentration and time duration. Sand was taken as the erodent material with solid concentrations ranging from 10 to 40% (by weight). The experiments were performed at four different speeds such as 750, 1000, 1250 and 1500 rpm with time duration of 30, 60, 90 and 120 min. In the present study, 5% TiO2 feedstock powder was blended with 80Ni-15Cr2O3 and 80Ni-15Al2O3 coating powders to increase their erosion wear resistance. Coating powders are deposited on pipeline material by thermal spray HVOF coating. Experimental results indicate that erosion wear has a high dependence on rotational speed, time duration and nature of erodent solid particles. Significant improvement in erosion wear resistance was also observed with the addition of 5% Titanium dioxide (TiO2) feedstock powder. 80Ni-15Cr2O3–5TiO2 coating shows better performance against solid particle erosion as compared to 80Ni-15Al2O3–5TiO2. The results are compared with uncoated mild steel pipeline material.

Effective utilization of F-type bottom ash by enhancement of pozzolanic properties

ABSTRACTThe objective of the present study was to investigate the physical, mineral, and rheological properties of grounded bottom ash for their utilization in stowing operation. It is found that the ash samples are enriched predominantly in silica; alumina and iron oxides fall under the category of F-type ash. Quartz and mullite are identified as major crystalline phases. The characterization results show that it can be utilized as a stowing material in coal mines. The result data obtained for critical velocity help to design a slurry pipeline system for the stowing of bottom ash slurry at any concentration and pipe size.

Pressure Study on Pipe Transportation Associated with Cemented Coal Gangue Fly-Ash Backfill Slurry

Cemented coal gangue-fly ash backfill (CGFB) slurry has commonly been used to control subsidence damage caused by underground coal mining. This paper discusses the characteristics of CGFB slurry fluidity in its pipe transportation. A general description about the components of the CGFB is provided involving the percentage of composition, particle size distribution (PSD) and rheological performance. The CGFB flow characteristics of the slurry pipeline were simulated in a straight pipe and 90° elbow pipe, respectively, combined with the pressure loss and conveying velocity distribution. With the help of the commercial computational fluid dynamic (CFD) code FLUENT, the modeling was conducted with various slurry feeding velocities. These results showed the local resistance loss in a bending pipe is significantly higher than the resistance in a straight pipe under the same conditions associated with CGFB transportation. The velocity distribution of the slurry solid particles in the slurry’s movement forward is more decentralized as the hydraulic inlet velocity increases. Based on these simulation data, a correlation was developed to predict the resistance loss of the CGFB slurry as a function of the hydraulic inlet velocity, pipe diameter and CGFB slurry rheological characteristics.

Optimization and Erosion Wear Response of HVOF Coated Pipeline Material at Different Impingement Angles

Background/Objectives: Erosion wear characteristic of pipeline material namely stainless steel SS-317L has been investigated with the help of a pot tester under various concentrations and fly ash as erodent was used. Methods/Statistical Analysis: In this paper, erosion wear response of slurry pipeline material is optimized by utilizing Taguchi’s experimental technique. Findings: The phenomenon of erosion wear response is too complex and the behavior has been studied. In this paper, the attempt has been made to expand a methodology to optimize the erosion wear response of pipeline material at various impingement angles 30, 45, 60 and 90 degree with the help of a mixture of slurry with water under various concentrations i.e. 30%, 40%, 50% and 60%. Fly ash and water was used as erodent to prepare the slurry mixture under various concentrations at different rotational were 600, 850, 1100 and 1350 rpm and time period of 60, 120, 180 and 210 min. Improvements/Applications: Erosion wear response is investigated with HVOF spayed coatings. It is also observed that the erosion wear response of WC-12Co-4Cr and Stellite-6 coated pipeline material SS-317L increase with the increase in the impingement angle till 30 degree observe maximum value and decreases with the impingement angle 90 degree. Keywords: Erosion Wear Rate, Fly Ash, HVOF Sprayed Coating (Stellite6 and WC-12Co-4Cr), Impingement Angles, Optimization etc, Rotational Speed, S/N Ratio, Stainless Steel (SS-317L), Taguchi Method

Mathematical simulation of transient operation modes of an electric drive of a centrifugal pump for a slurry pipeline

To develop new control algorithms for controlling slurry pumps, it is necessary to have a reliable mathematical model of their operation, convenient for computer simulation implementation. Therefore, the paper discloses a mathematical model of the joint operation of a centrifugal pump with a controlled asynchronous motor drive and a slurry pipeline. The results of transient modes computer simulation, carried out via the xcos application of the scilab software, are presented. This software is a freeware one and, therefore, available free of charge to most researchers. The paper provides an example of verification of the adequacy and performance of the proposed computer model, with the use of characteristics of the centrifugal slurry pump GrAT-225-67-3-2-2. The said model of a centrifugal pump is efficient and can be used during the study of dynamic processes in pipeline transportation systems, as well as in the synthesis of control algorithms for electric drives of pumping units.

Induction Hardening of a 0.40 % C Novel Microalloyed Steel: Effects of Heating Rate on the Prior Austenite Grain Size

This work explores the effect of heating rate on the prior austenite grain size and hardness of a thermomechanically processed novel niobium-microalloyed 0.40 % carbon low-alloyed steel intended for use in induction hardened slurry pipelines. The aim was to identify the heating rates that lead to the maximum hardness, for high wear resistance, and minimum prior austenite grain size, for high toughness. For this purpose, a Gleeble 3800 machine has been employed to simulate the induction hardening process and provide dilatometric phase transformation data. The prior austenite grain structure has been reconstructed from the EBSD results using a MatlabR script supplemented with MTEX texture and crystallography analyses. Heating rates ranged from 1 to 50 °C/s and the cooling rate was 50 °C/s. The results show that the prior austenite grain size greatly depended on the heating rate: compared to the lower heating rates, the maximum heating rate of 50 C/s produces remarkably fine prior austenite grains and a fine final martensitic microstructure after quenching. In addition, a relation between the heating rate and the deviation from equilibrium temperature has been established.

Application of high-frequency impedancemetry approach in measuring the deposition velocities of biomass and sand slurry flows in pipelines

Since the lower limit to operating velocities in slurry transport systems is influenced by deposition conditions, measuring the “deposition velocity” is an essential step in slurry pipelines’ design and operation. This study proposes a new experimental technique in measuring deposition velocities in slurry pipeline transport called the high-frequency impedancemetry approach. This non-invasive technique of measuring electrical properties of substances, based on their frequency-dependent behavior, was applied using a 16-electrode impedancemetry device on a 25m long closed-circuit pipeline to measure the deposition velocities of sand- and biomass–water mixture flows. Slurries of play and gravel sands, as well as wheat straw and wood chips biomass feedstock, were prepared over a range of concentrations (1.5–20wt% dry-matter), and deposition velocities were measured over a wide range of operating velocities (0.04–4.5m/s). Experimental measurements for sand–water mixtures were found to be in good agreement with empirical correlations derived previously through various analytical and mathematical techniques. In addition, for the first time, the deposition velocities for biomass–water mixtures were measured and found to be in the range of 0.21–0.8 m/s; surprisingly well below the common range of commercial pipelines’ operating velocities, i.e., 1.4–3.0m/s.

Terminal settling velocity of a single sphere in drilling fluid

The accurate prediction of terminal settling velocity of solid spheres in non-Newtonian liquids is important for various fluid-particle systems such as slurry pipelines, separation processes, hole-cleaning in drilling operations, and mineral processing. The standard practice for the prediction involves an implicit procedure that requires repeated iterations using Newtonian correlations. Wilson et al. developed an explicit method that allows direct (noniterative) prediction of the velocity in non-Newtonian liquids. Although very useful, the original Wilson model has an empirical constraint that limits its application. In this study, experiments are performed to measure the terminal settling velocity of precision spheres in Newtonian liquid (water) and non-Newtonian drilling fluids (Flowzan solutions). The Herschel–Bulkley three parameter model satisfactorily modeled the non-Newtonian rheology. Experimental data and similar measurements available in the literature are presented in this paper. The data exhibited the standard relationship between the drag coefficient and the Reynolds number. The original Wilson model was tested for these data points and was modified in this study to address its limitations. Consequently, it was observed that the modified version yielded more accurate results than the original model. Its prediction was especially better when the value of corresponding Reynolds number was more than 10.

Measuring Method of Solid-Liquid Two-Phase Flow in Slurry Pipeline for Deep-Sea Mining

In order to reduce the influence of fluid noise on the measurement of solid-liquid two-phase flow in slurry pipeline for deep-sea mining, the technique of virtual inductance is introduced to traditional capacitively coupled contactless conductivity detection (C4D), a measuring method for solid-liquid two-phase flow based on differential C4D is proposed, and the structure of differential C4D based on three electrodes is designed. The measuring device was verified in conductive fluid channels at different salinity. The results demonstrated that the amplitude of output voltage of the measuring device decreased obviously with the increase of the salinity of the fluid, and linearly associated with the size and volume concentration of the polymetallic nodules. Virtual inductance could reduce the requirement of C4D sensor for the excitation power. The measuring device had less noise of output signal and high accuracy. When the KCl solution containing salinity is at the average salinity of seawater 3.5% and the particle size of polymetallic nodules is from 0 to 25 mm, the output voltage increased from 0 to 87 mv. The maximum relative error in two-phase flow velocity measurement is 5.2%, which showed that the measuring method for two-phase flow in the slurry pipeline based on the differential C4D is effective.

Optimization and erosion wear response of slurry pipeline material with and without coating

Background / Objectives: In this paper, erosion wear response of slurry pipeline material is optimized by utilizing Taguchi’s experimental technique. Methods / Statistical Analysis: The investigation of erosion wear due to solid–liquid mixture flow took place with the assistance of a slurry erosion pot tester. The pipe material namely stainless steel SS-317L is utilized to lead the erosion tests. This erosion test is set up to impact the rotational speed, solid concentration and time with multi sized slurry. Fly ash was utilized as the erodent material. Findings: In these erosion tests, four experiments were performed. These four tests are performed at four different speeds 600, 850, 1100 & 1350 rpm and the concentration of solid-liquid mixture is 30%, 40%, 50 & 60% with time duration of these experiments are 60, 120, 180 and 240 min. Improvements / Applications: For protective coating, High-velocity oxygen-fuel (HVOF) spray process is used for depositing to coating powders Stellite-6 and WC - 12Co - 4Cr on the material namely stainless steel SS-317L. The S/N ratio of with and without HVOF coating of SS-317L varies from 44.88 to 29.77 (Uncoated), 64.43 to 37.09 (Stellite-6) and 80.00 to 49.25 (WC-12Co-4Cr) respectively. Rotational speed was resolved as one of the predominant factor which impacts the erosion wear response of SS-317L. Keywords: Erosion wear, Fly ash, HVOF sprayed coating (Stellite-6 and WC-12Co-4Cr), Optimization, Rotational Speed, Stainless Steel (SS-317L), Taguchi methodetc.

Effect of niobium and phase transformation temperature on the microstructure and texture of a novel 0.40% C thermomechanically processed steel

Field emission scanning electron microscopy, electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) have been employed to investigate the effect of niobium and phase transformation temperature on the evolution of microstructure and texture in a novel thermomechanically processed, medium‑carbon, low-alloy steel intended for slurry pipeline applications. Thermomechanical processing consisted of hot-rolling in the austenitic region with deformation both above the recrystallization limit temperature and below the recrystallization stop temperature. Immediately after rolling, specimens were directly quenched in water to two different temperatures of 560 °C and 420 °C and subsequently furnace cooled from those temperatures to simulate the cooling of coiled strip on a hot strip mill. The microstructure of samples quenched to 560 °C mostly comprised of upper bainite, whereas the samples quenched to 420 °C mainly consisted of lath-type lower bainite. The transformation texture of all samples at the mid-thickness position consisted of α, γ and ε-fibers with high intensities close to the transformed copper, transformed brass and rotated cube components. The addition of 0.013 wt% Nb refined the microstructure and sharpened the texture. The texture of the small fraction of retained austenite present in the final microstructures indicated that the main bcc texture components result from the brass and copper components in the parent austenite.