Slurry Transportation System Research Articles

Numerical investigation of power-law flow past two side-by-side identical circular cylinders

The non-Newtonian flow past multiple cylinders is widely encountered in engineering applications, such as slurry transport, petroleum drilling, and heat transmission systems using hot kerosene. However, the wake characteristics of non-Newtonian flow past multiple cylinders are far from well understood. This paper reports the numerical results of power-law flow past two side-by-side identical circular cylinders with a various gap ratio (G/D = 1.1–6.0) and a power-law index (n = 0.8–1.5) at a fixed Reynolds number (Re = 100) based on the incoming uniform flow velocity. Six wake patterns are identified, including the single bluff-body regime, deflected regime, in-phase regime, anti-phase regime, and two subclasses of flip-flopping regime (FF1 and FF2 regimes). The hydrodynamic coefficients of two cylinders are sensitive to both the gap ratio and the power-law index. The wake structure evolution is closely related to the wake patterns, and six modes of wake evolution are accordingly observed. Since the apparent viscosity of power-law fluid changes with the shear rate, the distribution of local Reynolds number (ReL) around the cylinder surface varies with the wake pattern. As it goes outward along the normal direction from the cylinder surface, the ReL shows a trend of increasing and then decreasing when n < 1, while the opposite trend is observed when n > 1.

Scale-up prediction of the head loss of a high concentration, non-Newtonian particulate slurry

The design of a mineral slurry transportation system is difficult because of the non-Newtonian nature of the flow at high slurry concentrations. The behavior of the slurry depends on many physio-chemical properties such as particle density, particle size distribution (PSD), particle shape, chemical composition, pH etc. This work presents a comparative study between three preferred methods of scale-up of the head loss in larger diameter pipelines, namely Bowen’s Method, rheological method and Wilson’s Method. The performance of each method is validated with the pipe loop test data in a 200 DN pipeline. A high concentration (>50% by weight) iron ore concentrate slurry was used for carrying out the above study. This work would be beneficial for engineers involved in the design and maintenance of the slurry pipelines with respect to the choice of the scale-up methods available for estimation of the head loss for a time independent, homogenous, non-Newtonian particulate slurry for both laminar and turbulent regime.

Erosion-corrosion behaviour of high manganese steel used in slurry pipelines

The regular replacement and maintenance of steel pipes used to transport slurry in oil sands mining and extraction continue to represent a major expense for oil sands operations. Pipeline steels such as API 5 L X65 and X70 are the main materials for the slurry transport system. In our previous work, dual-phase stainless steel showed excellent performance in aeriated (high dissolved oxygen) slurries operated at low to moderate velocities involving erosion-corrosion. However, the benefits of using stainless steel diminish as the oxygen in slurry is depleted or at higher slurry velocities at which mechanical properties, particularly deformation energy or strain-hardening capability, of the steel become more dominant. This article reports our recent studies on erosion-corrosion of high manganese steel at different slurry velocities (3.5 m/s and 5.5 m/s) and different dissolved oxygen levels (0.6 ppm and 3.8 ppm). The erosion-corrosion tests were performed at 60 °C in sand-containing slurry (20% vol. silica) with 500 ppm chloride, which simulated common field situation. Characterization of the steel was carried out with optical and scanning electron microscopy, energy dispersive x-ray spectrometry, x-ray diffraction technique, micro-mechanical probe, and electrochemical testing. The performance of the high manganese steel was compared to those of API 5 L pipeline steels commonly used in slurry transport, ASTM A1053 Gr.50 dual-phase ferritic-martensitic stainless steel, and AR400 martensitic hard plate. Results of this investigation demonstrate how the high strain-hardening capability of the high manganese steel produces an outstanding erosion resistance, which is more than two times as high as those of ferritic steels. The results are compared to those obtained through field trials performed in an oil sands coarse tailings pipeline.

Control and regulation of the density of technical fluids during their transportation by sea specialized vessels

The object of research is the process of transporting drilling slurry through specialized marine vessels of the Platform Supply Vessels class. The subject of research is the sedimentation stability of the drilling slurry along the height of the cargo tank, which is proposed to be defined as a relative change in vertical density near the surface and bottom of the cargo tank. The studies were carried out on a specialized sea vessel with a displacement of 7320 tons. The design of the vessel provided for the reception and transportation of drilling slurry in four cargo tanks located on the port and starboard sides of the vessel. It has been experimentally established that during the 48-hour transportation, the density of the drilling slurry in the bottom part increases to 19.7 %; decrease in density on the surface – up to 7.8 %; decrease in the sedimentation resistance of the drilling slurry along the depth of the cargo tank – up to 29.85 %. A variant of modernization of the drilling slurry transportation system by installing additional circulation pumps providing forced circulation of the drilling slurry between cargo tanks is proposed. By using programmable microcontrollers (performing turning on/off the circulation pumps), it is possible to provide the following conditions for transporting the drilling fluid: an increase in the density of the drilling fluid in the bottom part up to 0.3 %; decrease in density on the surface – up to 0.25 %; decrease in the sedimentation resistance of the drilling slurry along the depth of the cargo tank – up to 8.01 %. It has been experimentally established that the creation of additional circulation and automatic support of the sedimentation resistance of the drilling fluid in the range of 2–7 % contributes to: – increasing the relative performance of cargo pumps from 38–55 % to 92–96 %; – reducing the time of pumping drilling slurry from cargo tanks to the drilling platform from 7.1 to 3.2 hours; – maintaining the technical condition of equipment, pipelines and elements of the drilling slurry transportation and pumping system.

Analysis of minimum specific energy consumption and optimal transport concentration of slurry pipeline transport systems

Slurry pipeline transport is widely used in several industrial processes. Calculating the specific power consumption (SPC) and determining the best working conditions are important for the design and operation of transportation systems. Based on the Shanghai Jiao Tong University high-concentration multi-sized slurry pressure drop (SJTU-HMSPD) pipeline-resistance-calculation model, the SJTU-SPC model for calculating the power required to transport a unit volume of solid materials over a unit pipeline length is established for a slurry transport system. The said system demonstrates a uniformity coefficient in the 1.26–7.98 range, median particle size of 0.075–4 mm, particle volume concentration of 10–60%, and pipeline diameter of 0.203–0.8 m. The results obtained were successfully verified against existing experimental data. The influence of parameters, such as particle-gradation uniformity coefficient, median particle size, pipe diameter, and particle volume concentration, on the SPC were analysed. The results revealed that the greater is the uniformity coefficient, the smaller is the minimum specific energy consumption and the larger the optimal transport concentration for a constant, median particle size slurry. As observed, the optimal transport concentration for broad-graded sand equalled approximately 48%. These results supplement the conclusions of existing research, indicating that the optimal transport concentration is approximately 30% and provides theoretical support for high concentration transportation of broad graded slurry.

Neural network prediction of slurry erosion of heavy-duty pump impeller/casing materials 18Cr-8Ni, 16Cr-10Ni-2Mo, super duplex 24Cr-6Ni-3Mo-N, and grey cast iron

The aim of the present study is to develop a neural network model for the prediction of slurry erosion (SE) of heavy-duty pump impeller steels and casing material. The heavy-duty pump impeller has a wide range of applications like slurry transportation system and coal conveying system of thermal power stations, and various other industries like mining, chemical and marine industry. In the present study, the slurry erosion performance of three different pump impeller steels namely 18Cr-8Ni, 16Cr-10Ni-2Mo and super duplex 24Cr-6Ni-3Mo-N, and one pump casing material namely Grey cast iron was tested. The SE experiments were carried out on a laboratory scale pot tester using the sand as an erodent. A data set was produced to develop a prediction-based neural network (NN) model and 70% of this data set was used as input to NN model. The learning of NN model was based on an artificial neural network (ANN) and used to build a prediction model that can predict the results while the input data was supplied to it. Firstly, the data were divided into training, validation, and testing. The NN model was trained on 70% of the original dataset and validated by another 15% data. A total of 30 training epochs were performed for training, testing, and validation of the model. The validation of the model indicates that the build NN model was the best fit and comprises no over-fitting and under-fitting issues. In the end, the prepared NN model was given the remaining 15% data for testing. It outputs the corresponding values for each input. These predicted values are then compared with the actual ground truth to check the robustness of the designed model. The various measures used for evaluating the model were R2 (coefficient of determination), Root mean square error, etc. Results show that 18Cr-8Ni steel exhibits the best SE performance followed by 16Cr-10Ni-2Mo, 24Cr-6Ni-3Mo-N, and Grey cast iron.

Tribological performance of thermally sprayed Ni-Cr2O3 and Ni-Al2O3 coatings on pipeline steel using Taguchi’s approach

Abstract Slurry transportation systems are widely used as the transportation of solid materials such as coal to thermal power plants and fly ash, bottom ash, etc., to disposal areas with the help of a carrier fluid such as water. The components used in these systems such as pipes, pumps, impeller, casing, etc. suffer from the slurry erosion wear. In this investigation, the main focus is to study the effect of various slurry parameters on the erosion wear by using Taguchi’s Method. The material selected for the erosion tests is pipe material i.e. M.S. (Mild Steel). Fly ash was taken as erodent media. The particle size range of fly ash was taken from

ANOVA studies and control factors effect analysis of cobalt based microwave clad

In today’s world slurry handling equipments are facing lot of engineering problems which is namely erosion. Slurry erosion plays a very important role in the design and operation of slurry transportation systems. In the work an attempt is made to reduce slurry erosion by cobalt based clad developed through microwave energy. The microwave clads are developed on AISI 420 substrate with a microwave exposure of 07 min. The developed clad shown great improvement in the erosion resistance than substrate. Slurry erosive wear studies were carried out with focus of three important parameters such as speed, impact angle and time of slurry exposure. ANOVA and control factors analysis studies were carried out with 95% of confidence level. Impact angle shown most dominating parameter on wear rate. Mixed mode of erosion was noticed on the target surface.

A review on erosion wear of different types of slurry pump impeller materials

Slurry transportation system has two basic types; packed flow and slack flow. A typical slurry transportation system considering conditions like maximum design and minimum flow, may work well for a maximum flow, but may function incorrectly in case of minimum volume. Different pneumatic or mechanical ash conveyors are employed based on the ash handling systems.

Rapid Wear Modelling in a Slurry Pump Using Soft 3D Impeller Material

Slurry transport systems are often limited in run length by the life of the pump internals, especially the impeller. The present work investigated abrasive wear of the impeller of a Hayward Gordon XR2(7) Torus Recessed Impeller slurry pump in a flow loop. The stock stainless steel impeller was replaced by a set of plastic test impellers with the same nominal geometry, fabricated by additive manufacturing (3D printing). A parametric set of abrasive wear experiments was conducted at five pump rotational speeds and three solid concentrations of garnet slurry in a pipe flow loop. Pump performance tests were conducted using impellers with progressive wear conditions, to investigate how a worn impeller affects hydraulic power delivery. A parabolic fit was imposed to describe the relationship between head and flow rate, and an empirical model was proposed to predict the pump head with damaged impellers. When the rotational speed is high, the damaged impeller has a larger effect on the pump’s performance than when the rotational speed is low. The head difference between the undamaged impeller and a 7.62%-mass-loss damaged impeller was 1.5 m at 1750 rpm rotational speed, however, for 850 rpm, the head difference was 1 m. Implications for pump diagnostics in other types of systems are discussed. This experiment gives a method for rapidly assessing wear locations, and provides a tool to predict wear rates on harder materials if scaling parameters are available. This first attempt at a scaling law is not reliable enough to accurately predict the wear rate for specific conditions, but shows the relative wear as a function of pertinent parameters.

Effect of Rock Abrasiveness on Wear of Shield Tunnelling in Bukit Timah Granite

The abrasiveness of rocks significantly influences the wear endured by excavation tools in tunnel boring machines (TBMs). In slurry shield TBMs, wear occurs not only in excavation tools but also in discharge pipes and pumps of slurry transport systems. To explore this phenomenon, this study investigated the effect of rock abrasiveness on the wear of both disc cutters and slurry discharge pipes in slurry shield TBMs. The radial wear of disc cutters and the thickness of slurry discharge pipes were measured and monitored at a TBM site in Singapore. The relationship between the weathering grade of Bukit Timah granite and the wear coefficient of disc cutters was analysed, and a correlation between the Cerchar Abrasivity Index values and the wear coefficient of 19 inch disc cutters was suggested. Additionally, the average wear rates of slurry discharge pipes used for Bukit Timah granite were determined based on the pipe thickness measurements. The wear rates of weathering grades G(I) to G(IV) of Bukit Timah granite were observed to be highly similar to each other, whereas the wear rates of G(V) grade and mixed ground were 1.55 times higher than those of the G(I) to G(IV) grades. The correlation between the slurry discharge velocity and the wear rate in slurry discharge pipes was thus derived. The accurate assessment of the effect of rock abrasiveness on both the wear of disc cutters and the wear rate in slurry discharge pipes, investigated in this paper, will highlight the need for efficient maintenance of the excavation tools in TBMs and encourage the development of various equipment wear prevention measures in order to minimize overall construction costs and time.

Effect of hot forging on the slurry erosion wear of AISI316 and AISI410 steel

Evaluation of slurry erosion is one of the most important aspects while designing any slurry transportation system as it is a major cause for inefficient functioning and eventually failure of different components of the system. The aim of present work is to investigate the effect of hot forging on the slurry erosion behavior upon two materials namely austenite stainless steel (SS316) and martensitic stainless steel (SS410), experimentally. Hot forging has been done using a Birson Friction Screw Press machine by utilizing a temperature range from 850 °C to 950 °C and maintaining a constant strain rate of 10 s−1. It is observed that the hot forged samples are more erosion resistant than the ‘as received samples’ (ARS). It is also found that the samples hot forged at 950 °C shows the maximum slurry erosion resistance. It is also concluded that the SS410 is more erosion resistant than the SS316 for both ARS and hot forged samples.

A Study of the Effect of Medium Viscosity on Breakage Parameters for Wet Grinding

The rheological behavior of mineral slurries shows the level of interaction or aggregation among particles, being a process control variable in processes such as slurry transportation, dehydration, and wet grinding systems. With the aim to analyze the effect of medium viscosity in wet grinding, a series of monosize grinding ball mill tests were performed to determine breakage parameters, according to the generally accepted kinetic approach of grinding processes. A rheological modifier (polyacrylamide, PAM) was used to modify solutions viscosity. A model was proposed by means of dimensional analysis (Buckingham’s Pi theorem) in order to determine the behavior of the specific breakage rate (Sj) for a ball grinding process in terms of the rheology of the system. In addition to this, a linear adjustment was established for the relationship between specific breakage rates with and without PAM addition, based on the reduced viscosity, μr. Furthermore, within a certain interval of viscosity, it was proved that an increment of viscosity can increase the specific breakage rate, and consequently the grinding degree.

Numerical simulation of a centrifugal slurry pump handling solid-liquid mixture: Effect of solids on flow field and performance

The effect of solids on a centrifugal slurry pump performance is a major concern to the design of slurry transportation system. In the present study, the multiphase modeling of centrifugal slurry pump is performed using two models, Mixture and Eulerian-Eulerian multiphase. Sliding mesh approach is employed for unsteady simulation of the pump. The accuracy of the simulations is ascertained by comparing the performance characteristics of the pump obtained numerically and experimentally. Experimental results are obtained by measurements in a pilot plant test rig with three different mean size sand particulate slurries. The Eulerian-Eulerian multiphase model predicted the effect of the solids on pump performance close to the experimental results as compared to Mixture model. The obtained accuracy with Eulerian-Eulerian model for predicting the effect of solids on head and efficiency is around ±2% and ±3%, respectively. The predicted results using Eulerian-Eulerian model confirm that the head and efficiency of the pump decrease with the increase in particle size and concentration. The particles of high specific gravity show less reduction in head and efficiency of the pump. Further, the effect of variation in particle size and concentration on the flow field in the impeller and casing has also been analyzed at best efficiency point operation. Non-homogeneous suspension of particles inside the blade channels and casing passages is examined. The particulate concentration is observed higher near the impeller back shroud, pressure side of the blades, and non-suction side of the casing as compared to other locations.

Experimental Investigation on Slurry Erosion Behavior of 304L Steel, Grey Cast Iron, and High Chromium White Cast Iron

The materials used for the slurry transportation system experience erosion wear due to the impact of suspended solid particles. In the present experimental investigation, a large size slurry pot tester was used to investigate the slurry erosion behavior of steel 304L, grey cast iron, and high chromium white cast iron in the velocity range of 9.0–18.5 m/s. Experiments were conducted by rotating the wear specimens in the pot tester at 1% weight concentration of Indian standard sand. The erosion behavior of the three target materials was evaluated by varying the orientation angle from 15 to 90 deg and particle size from 256 to 655 µm. The erosion rate was found to increase with velocity having power index value varying between 2 and 3, which increases with an increase in impact angle and depends on the target material. The erosion rate of the material also increases with the increase in particle size with the power index varying between 0.8 and 1.4 depending on the target material. No significant change was noticed in the mechanism of erosion of the target materials with the variation in velocity in the present range of test conditions. Empirical correlations are proposed to estimate the total erosion rate of all the three materials as a contribution of cutting and deformation wear.

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.

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.

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.

Influence of solid concentration on rheological characteristics of fly ash-water suspension

Coal is the primary source of energy in almost every nation. As the energy demand is increasing, a greater amount of ash is generated as a result of increased coal consumption. The present study is aimed to investigate the physical, chemical and rheological properties of fly ash and its suspension with water for the design of a slurry transport system. The mineralogical composition of the fly ash shows large fraction silica and alumina. The rheological analysis shows that at lower concentrations (10-30%), the slurry behaves like a Newtonian fluid whereas it behaves like a non-newtonian fluid at higher concentrations (40-60%). The rheological characteristics can further used for the prediction of flow characteristics of the slurry in a horizontal pipe.

Tribological analysis of WC–10Co–4Cr and Ni–20Cr2O3 coating on stainless steel 304

Centrifugal slurry pump is widely used for transportation of solids through pipeline in many chemical and mining industries. Erosion wear considered as one of the important parameter which plays significant role in slurry transportation system by affecting both initial cost and life of its components. 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 centrifugal slurry pump material stainless steel (SS304) to establish the influence of rotational speed, particle size, solid concentration and time duration. Sand and fly ash were taken as erodent materials with solid concentrations ranging from 30 to 60% (by weight). The experiments were performed at four different speeds namely 600, 900, 1200 and 1500rpm with time duration of 90, 120, 150 and 180minutes. WC–10Co–4Cr and Ni–20Cr2O3 coating powders were used to increase the erosion wear resistance. Coating powders are deposited on pumping material by supersonic flame of high velocity oxygen fuel (HVOF) coating. Experimental results indicate that erosion wear has high dependence on rotational speed, time duration and nature of erodent solid particles. Significant improvement in erosion wear resistance was also observed by using WC–10Co–4Cr coating over Ni-20Cr2O3.