Horizontal Pipeline Research Articles

Heavy oil-water dispersed flows in horizontal pipelines using bio-additives with energy analysis: Experimental and numerical investigations

Heavy oil and water dispersed flows in a 0.0254 m, 0.0381 m, 0.0508 m ID horizontal pipelines (Pipeline length = 2.5 m) were investigated experimentally and numerically (at steady state) without and with additives by varying the temperature from 25 °C to 50 °C by considering power law (i.e., for emulsion) rheological behavior. The development of boundary layer, pressure drop, velocity profile, boundary layer thickness, and wall shear were discussed in these numerical investigations without and with water, ML (i.e., a natural extract from Madhuca Longifolia), and PS (i.e., potato starch) via pipeline transportation of heavy oil. The pressure drops in the numerical simulations were compared with the available experimental results and found in qualitative agreement (i.e., max error ±7%). The pressure drop from the inlet to the outlet was decreased with an upsurge in the concentration of bio-additives in the aqueous phase of the heavy oil emulsion and temperature. The development of the boundary layer was significantly varied after adding water and bio-additives to the heavy oil. The ratio of boundary layer thickness and pipe length is reduced by increasing the additive's temperature and concentration in the heavy oil-water flows. Furthermore, the reduction in wall shear occurred after efficiently adding water and bio-additives to the heavy oil during transportation. The comparative studies also carried out between the influence of additives on the hydrodynamic parameter. The bio-additives (ML and PS) in the aqueous phase improve the hydrodynamics of heavy oil flow in the pipeline. Natural extract ML improves the hydrodynamics of heavy oil flow through the pipeline than potato starch. The application of numerical investigations can significantly enhance understanding the hydrodynamics of the heavy oil/emulsion's transportation via pipelines with greater accuracy for complex pipeline configurations.

An Improved Model to Calculate Pullback Force of Trenchless Horizontal Directional Drilling Pipeline

In the pullback operation of horizontal directional drilling pipeline crossing, the existing calculation and prediction models of pullback force are relatively simple. Each pullback force maze greatly simplifies the wellbore trajectory and fails to make a detailed analysis of the pipeline stress and external resistance when the pipeline is pulled back in each characteristic trajectory area. The factors considered are relatively simple. Therefore, it is necessary to improve the calculation method of pullback force. This paper aims to establish an improved model, enhancing the earth pressure calculation method of unloading arch and winch calculation method, and carries out an example calculation of the improved formula. Therefore, it is necessary to study the pullback process of horizontal directional drilling pipeline. Firstly, this paper analyzes the calculation method of pullback force in horizontal directional drilling; studies the calculation formula and principle of common pullback force through examples; obtains the advantages, disadvantages, and applicable scope of different formulas; and improves the calculation model of pullback force and step resistance. The numerical simulation of the step crossing process is carried out, and the variation law of local stress and strain of the pipeline and relevant conclusions are obtained. The results show that the estimates of the winch calculation method are close to the actual pullback load of the project. The earth pressure calculation method of the unloading arch and the winch calculation method are improved, and a more stable and reliable calculation formula is obtained, which provides more valuable calculation data for the actual project. In the process of pullback, the pipeline will encounter step resistance after passing through the soft and hard staggered stratum, which will suddenly increase the increment of pipeline pullback force and lead to engineering accidents. If the pullback load suddenly increases and then decreases, it may encounter similar pipeline collision accidents. At the same time, emergency measures can be taken to prevent the crossing accident and ensure the safe pullback of the pipeline.

The technologies for the removal of coal technogenic deposits in the form of highly concentrated hydro mixtures

An analysis of the existing beneficiation coal waste storage facilities was carried out and ecologically friendly ways of lowering the water level and removing man-made deposits in the form of highly concentrated aqueous mixtures were carried out. The methodology for calculating the parameters and regimes of transportation for the man-made deposits waste with a high content of pollutants in the form of highly concentrated aqueous mixtures was developed. Models of the processes that occur during the extraction and transportation of man-made deposits in the form of highly concentrated aqueous mixtures were developed taking into account promising technologies. In case of an aqueous mixture with the significant initial tangential stress value, the transport of a highly concentrated aqueous mixture model along a vertical pipeline using a screw conveyor was developed. In this case, it is assumed that the aquous mixture will be lifted up at a height that ensures a nonpressure flow to the levee, where the aqueous mixture will be liquefied and its further transportation by pressure transport, vehicles or railway transport. The model of the process of the pressure flow of a highly concentrated aqueous mixture through the horizontal pipeline, depending on the transportation distance, provides for the use of centrifugal type pumps or piston pumps. Depending on the relative radius value for the undisturbed core of flow, the model takes into account the three most probable flow modes of highly concentrated aqueous mixtures through a circular cross-section pipeline and allows to perform both design and verification calculations. When the gravity force is used to transport a highly concentrated aqueous mixture to the shore, a mathematical model of nonpressure flow process of an aqueous mixture along an inclined channel with a rectangular cross-section was developed. This model takes into account the channel inclination angle, its width and the rheological parameters of the aqueous mixture and allows to calculate the geometric parameters of the channel, which are necessary to ensure the predefined transportation distance with the required flow rate. The results of the study could be applied for coal beneficiation waste storage facilities when they are out of maintenance, which will contribute to the elimination of technogenic impact on the environment, while for waste storage facilities that operate, appliance of the proposed technologies is a way of their size containing. Keywords: coal beneficiation waste storage, man-made deposits, highly concentrated aqueous mixtures.

Experimental Study on Heavy Oil Drag Reduction in Horizontal Pipelines by Water Annular Conveying

Transportation of heavy oil by the so-called water-ring technique is a very promising method by which pressure drop and pollution can be significantly reduced. Dedicated experiments have been carried out by changing the phase’s density, viscosity, velocity and interfacial tension to systematically analyze the characteristics of the water ring. On the basis of such experimental data, a mathematical model for pressure drop prediction has been introduced. This research shows that as long as the density of oil and water remains the same, a concentric water ring can effectively be formed. In such conditions, the oil-water viscosity difference has little effect on the shape of water ring, and it only affects the pressure drop. The greater the viscosity of heavy oil, the smaller the pressure drop of the oil-water ring transportation system. The influence of phases’ interfacial tension on the characteristics and pressure drop of the heavy oil-water ring can be considered negligible. The pressure drop prediction model introduced on the basis of the Buckingham’s principle provides values in good agreement (95%) with the experimental data.

Numerical Simulation of Two-Phase Water-Oil Flow in a Horizontal Pipe Using the Smoothed Particle Hydrodynamics Method

In this work, the numerical code DualPhysics, based on the Lagrangian particle and mesh free method Smoothed Particle Hydrodynamics, has been employed to solve the slightly compressible isothermal two-phase water-oil flow. The continuity and momentum equations are solved, and we used the modified Tait equation of state to determine the pressure. To validate the numerical code, we solved the modified Couette flow of two fluids. As a practical case, we solved the isothermal and two-dimensional two-phase water-oil flow. The mixing of the fluids occurs after passing through a 45 degree Y junction placed at the entrance of the horizontal pipeline. Results showed the potential for using the numerical code, although some modifications and alterations are still necessary to solve practical problems.

Numerical Simulation on Gas-Solid Two-Phase Flow in Horizontal Pneumatic Conveying Pipe Based on DPM Model

The determination of pipe deposition and optimum conveying velocity in pneumatic conveying has an important impact on conveying efficiency. The Euler-Lagrange method DPM model is used to analyse five different particle sizes and densities of small particles, and the flow pattern in the horizontal pipeline at different particle sizes and densities is derived from the graphs of the maximum discrete phase concentration, particle trajectory and discrete phase concentration distribution for each working condition. The simulation results show that the deposition increases with particle size and density, the optimum conveying speed increases with particle size and density, the larger the deposition, the larger the required conveying velocity. The velocity of 2 m/s can make the particles below 20μm suspended transport, the velocity of 4 m/s allows particles with a particle size of 30μm and a density of 1000 kg/m3 or less to be transported in suspension and 6 m/s allows particles with a density of 2000 kg/m3 or less to be transported in suspension. The aim is to provide a reference for the design of pneumatic conveying systems and the selection of the optimum conveying velocity.

The Study on Void Fraction Prediction of Gas-liquid Two Phase Flow Based on Convolutional Neural Network

For the gas-liquid two phase flow in the horizontal pipeline, at the center angle the void fraction of the different liquid phases is calculated with the finite element simulation software, and then a soft measurement model of the void fraction is established. By comparing with traditional recursive augmented least squares (RELS), particle swarm optimization (PSO), and simulated annealing-based PSO, the void fraction soft measurement model is identified and calculated separately. The segmentation optimization results of PSO based on simulated annealing have higher accuracy and stability than RELS and PSO, but as the number of center angles increases, the relative accuracy and stability of the system will deteriorate. And the characteristic is not conducive to the calculation and analysis of data results. By combining the actual model, the convolutional neural network weight update algorithm is added to the LSTM, and the RNN-LSTM convolutional neural network is used to predict the void fraction of the second half the region. It improves the effect of RNN gradient problem on learning ability and improves learning ability. Through comparison, it is found that the convolutional neural network based on RNN-LSTM has a better prediction effect, improves the accuracy and stability of the system, and provides a new method for the measured void fraction of twophase flow.

Evaluation of heat transfer augmentation and pressure drop by water/ethylene glycol nanofluid

The turbulent convective heat transfer behavior of CaCO3/TiO2/CuO nanocomposite dispersions in water/ethylene glycol is investigated experimentally in horizontal pipe-lines at constant heat flux at various in the Reynolds number range of 2900–18200 at 30 °C, heat flux of 800 kW/m2, and nanocomposite concentration of 0.01–0.1 Vol. %. The results showed considerable enhancement of convective heat transfer using the nanofluids. The enhancement was particularly significant in the entrance region, and was much higher than that solely due to the enhancement on thermal conduction. The Nusselt number and friction factor at 0.1 vol. % is greater than that values of water/ethylene glycol about 34.5 % and 18.9 %, respectively. The pressure drop increased with the concentration more than 3.6 % and decreased thereafter. Also, heat transfer coefficient in rough pipe-lines was higher than that in smooth pipe-lines at the same Reynolds number and it enhanced as the diameter decreased. Eventually, the greatest thermal performance factor of the nanofluid was 1.28 at 0.1 vol. % and Reynolds number of 4800.

The Impact of Swirls on Slurry Flows in Horizontal Pipelines

In deep ocean transportation pipeline, the swirling internal flow has a significant impact on the marine minerals transportation efficiency and safety. Therefore, the present work investigates various swirl flow motions for the slurry transport characteristics of the multi-sized particulate flow in a horizontal pipeline. Since the internal flow is a liquid-solid-solid mixture, a steady-state three-dimensional Eulerian-Eulerian multiphase approach in conjunction with the k-ω SST turbulence model is implemented for numerical simulation in the commercial CFD software ANSYS FLUENT 17.0. Numerical predictions of the mixture solid concentration distributions are generally in good conformance with experimental measurements. It is clearly revealed the transition of flow regime from heterogeneous to pseudo-homogeneous with the increasing level of swirl intensity at inlet. Compared to non-swirling flow, the swirling flow is of benefit to the multi-sized solid suspension capacity and the transportation efficiency. Moreover, the intense swirling vortex results in a strong influence on the characteristics of the lubrication layer formed by fine solid particles near the bottom of the pipe. These results provide valuable insights regarding the influence of swirl flow on the transport process for deep ocean mining.

Frictional behaviour of wheat straw-water suspensions in vertical upward flows

The use of biofuels helps mitigate greenhouse gas emissions. Earlier studies have shown that transporting biomass in horizontal pipelines in the form of water-based slurries significantly reduces transportation costs. The frictional behaviour of water-based chopped wheat straw slurry in a vertical pipeline has not been studied and this is the focus of this study. In situ concentrations of water-based conventional solids of medium sand, glass beads, and fine sand and straw slurry flows were determined by measuring their delivered concentrations in pseudo-homogeneous regimes for prepared concentrations of 1–6% (dry volume of conventional solids) and 5–25% (saturated mass of straw), respectively. Two grades of sand and glass beads with mean particle diameters of 0.103, 0.447, and 0.5 mm, respectively, and straw with a nominal particle length of 19.2 mm were utilised. The delivered concentrations for the straw slurries and fine sand were close to their corresponding prepared concentrations and were homogeneous. There was a large discrepancy between prepared and delivered concentrations for the medium-sized sand and glass beads slurries. The pressure drop of straw slurries over the range of velocities of 0.5–4.2 m s −1 and mass concentrations of 5–25% through the vertical pipe showed a maximum drag reduction of 19% at a concentration of 25% (mass) and at a 3.5 m s −1 velocity. For concentrations of 5–20% (mass), the straw slurries showed drag-reducing capabilities in the mixed and turbulent flow regions for various velocities that were different from horizontal flows. • The pumping of aqueous slurries of chopped wheat straw was studied in a pipeline. • Friction losses in the vertical pipeline were measured over a range of variables. • The delivered and prepared concentrations for wheat straw slurries were identical. • Straw slurries in vertical upward flows behaved differently than horizontal flows. • Drag reduction appeared at even low velocities and mass concentrations of straw.

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

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.

Experimental study on fine particle deposition in supercritical water natural circulation

An experimental platform for the movement and deposition of fine particles in critical water was developed. The platform is equipped with a viewport to visually observe the movement of fluid and particles, which successfully solves the difficult problems such as easy leakage of viewport and inability of viewport materials to withstand ultra-high temperature and pressure. Through experiments and calculations, it is found that the physical properties of supercritical water and the characteristics of natural circulation are more likely to cause the deposition of finer particles. On the wall of the vertical pipe and the wall of the visible section, there are a few particles deposited due to the strong diffusion coefficient and high dielectric coefficient of supercritical water. At the bend, owing to the inertial centrifugal force, together with the temperature gradient and turbulence, a large number of particles are deposited at the bottom of the bend. In the horizontal pipeline, due to the direct action of gravity on the wall surface, together with a higher temperature gradient and turbulence force, more particulate matter will be deposited.

Flame propagation and CO/CO2 generation characteristics of lignite dust explosion in horizontal pipeline

Abstract To reveal the flame propagation and CO/CO2 generation characteristics of coal dust explosion, lignite dust cloud is studied through experiment and numerical simulation in a horizontal pipeline apparatus. The result indicated that within 0.5 s after explosion, the flame propagation distance rapidly increases until the explosion reaction is sufficient. FLUENT is used to simulate the flame propagation and CO/CO2 generation characteristics. It is found that the simulation error is acceptable and the simulation result is consistent with the experimental result. The explosion space is divided into five zones by simulating the flame temperature. It also revealed that z = 0.3 ~ 0.6 m in the pipeline generates more CO because it is closed to the ignition zone. As the explosion spreads through the pipeline, the generated CO accumulates to the bottom of the pipeline, and the generated CO2 accumulates more in the upper part of the pipeline.

Effect of oscillation flow induced by lattices on a horizontal gas–solid two-phase flow

This study is focused on reducing the pressure drop, conveying velocity, and power consumption in a horizontal gas–solid flow. Four types of lattice models, which are fixed in the particle inlet, are proposed to easily generate the oscillation of the wake flow to easily convey the gas–solid two-phase flow. A horizontal pipeline with an inner diameter of 80 mm and length of approximately 5 m was used. Polyethylene particles with an average diameter of 2.3 mm and density of 978 kg/m3 were employed as conveying solid materials. The experimental ranges of the average gas velocity and solid mass flow rate were 10–16 m/s and 0.10–0.47 kg/s, respectively. Compared to the nonlattice gas–solid flow, reductions in the total pressure drop, conveying gas velocity, power consumption, and additional pressure loss were achieved in the range of lower gas velocity when using the lattice model. The highest reduction rates of the minimum conveying velocity and additional pressure drop were approximately 5.12% and 15.2%, respectively. In the acceleration region, the particle concentration in the flows with the lattice model was larger than that in the nonlattice flow near the upper part of the pipe and lower than those in the nonlattice flows in the lower part of the pipe. The time-mean axial particle velocity and particle fluctuating velocity in all lattice model flows were higher than those in the nonlattice flow, according to particle image velocimetry measurements, particularly in the upper part of the pipe.

Characterization of the hydrodynamics within a toroid wear tester

AbstractThe toroid wear tester (TWT) is a lab‐scale device used for the assessment of slurry erosion in pipelines. Historically, its application has been limited to the relative ranking of material performance under different slurry flow conditions; however, recent studies have indicated that TWT tests could be predictive and directly applied to slurry pipeline design—provided that the flow inside a TWT is better characterized. In the present study, air‐liquid multiphase flow inside the TWT was investigated. Torque measurements were taken to characterize friction loss for different air‐liquid combinations. A visualization experiment was also conducted to evaluate flow patterns within the TWT. In the experiment, the displacements of spherical glass beads were used to estimate velocity vector fields for different TWT rotational speeds. A computational fluid dynamics (CFD) analysis was also conducted to complement the experimental measurements. A 3D transient analysis using the volume of fluid (VOF) approach was used to model the system. The simulation results agreed closely with the experimental findings. Furthermore, the simulations revealed that strong secondary flows (back flow, rotation) exist in the TWT. These type of flows do not occur in horizontal pipelines. Therefore, to use the TWT as a tool for slurry pipeline wear assessment, the differences in the flow field between the two systems must be properly quantified.

Unstable Transients Affecting Flow Assurance during Hydraulic Transportation of Granular Two-Phase Slurries

Hydraulic two-phase transport applied in the dredging, mining, and deep-sea mining industries involves the transportation of sand, gravel, polymetallic nodules, or other particulate tailings as a solids phase and water as a liquid phase. Regardless of the type or size of the granular material, the slurry flow is always subject to transient behavior. Most transient behavior can be attributed to the centrifugal pump as variations in pump pressure and mixture velocity over time, but transients can also be caused by microscopic slurry mechanisms, specifically the amplification of density waves in a pipeline. Density wave amplification in horizontal pipelines at mixture velocities just above the deposition limit velocity was reported and researched in the 1990s. New experiments showing a density wave amplification in a system with combined vertical and horizontal pipelines and at mixture velocities far above the deposition limit suggest that another type of density wave amplification mechanism exists. The newly proposed density wave amplification mechanism is hypothesized to be caused by a change in average particle velocity as the slurry flows from a vertical pipe into a horizontal pipe. Density waves that grow too large cause system blockages or possibly a failure of the pump drive. This article considers centrifugal pump–induced transients and density wave amplification effects separately and how these effects influence each other. Three case studies showing density wave amplification are analyzed, one from the literature and two from new data sets. Furthermore, the causes of these transients are discussed, and where possible, solutions are proposed to avoid these undesirable instabilities.

Experimental Study 0f Drag Reduction Phenomena in the Horizontal Tube with Nano SiO2 by Neural Network - Genetic Algorithm

In this study, nano-silica oxide's effect as a Drag Reducing Agent (DRA) of water flow in a 12.7 and 25.4 mm galvanized pipe was investigated. The studied parameters include Nano silica oxide concentration, Flow rate, temperature, and tube pipe diameter. To develop the conditions in preparing the Nano-particle on Drag Reduction (DR), nano-particles were provided in the top water-based fluid. To have a comprehensive analysis of process folding conditions, the experiments were carried out with three different drag-reducing concentration agents with three various temperatures and three different flow rates. Moreover, as a new method in this study, the experimental (Drag reduction percent) outputs were evaluated and analyzed using the Artificial neural network which is optimized by a genetic algorithm. In the consequence of algorithm genetic, the highest rate of drag reduction occurred at a horizontal pipeline 12.7 mm, temperature 41.07 °C, and a concentration of 0.628 with a 1441.84 flow rate was 25.84%.

Experimental investigation on vortex-induced vibration and solid-structure impact of a near-bottom horizontal flexible pipeline in oblique shear flow

Vortex-induced vibrations and solid-structure impacts of a horizontal flexible pipeline in the vicinity of a bottom wall boundary are experimentally investigated in a water flume. A neutrally-buoyant submerged pipe, with a length-to-diameter ratio of about 87 and fixed end supports, is subject to a shear flow with an oblique angle of 30°. The initial gap-to-diameter ratio between the wall and the pipe is equal to 0.2. A non-intrusive measurement with high-speed cameras is employed to simultaneously capture the space–time varying in-line and cross-flow vibrations in the normal flow reduced velocity range of 3–15 with a maximum Reynolds number of about 2780. Experimental results highlight new pipe equilibrium profiles and modal response branches being significantly broadened due to the wall proximity. Two solid-pipe impact features are discussed, including single-segment and two-segment alternating impacts depending on the dominant oscillation mode of the flexible pipe. Both the response amplitude and frequency increase with the reduced velocity, resulting in a more frequent impact with a greater impact force. A temporal evolution from a single point contact to a segment contact is observed for the two-segment alternating impact. Nevertheless, the lengths of the two contact segments are different as a result of the asymmetric response profile. In all cases, the pipe transversely impacts the bottom wall introducing a perturbation transmission along the pipe, which leads to the multi-mode, multi-frequency and asynchronous in-line and cross-flow oscillations with a 1:1 and 2:1 resonance. Due to a momentum energy consumption, the pipe experiences a slow post-impact bouncing phenomenon, contributing to a longer temporal period of the fluid–pipe interaction with a wall impact.

Computational fluid dynamics modeling of slurry flow in horizontal pipes: Effect of specularity coefficient on hydraulic gradient

The specularity coefficient is an important input parameter in the Johnson and Jackson boundary conditions. Thus far, research on this parameter has been lacking in the field of slurry flow simulations. In this study, the integration of the Eulerian–Eulerian two-fluid model with kinetic theory of granular flow and Johnson and Jackson boundary conditions is used to simulate the transportation of sand–water slurry in horizontal pipelines. A range of flow conditions, including high and low velocities, high and low concentrations, coarse and fine particles, and large and small pipes, is considered to study the effect of the specularity coefficient on the predicted hydraulic gradient. Then, the simulation results are compared with previous experimental measurements to determine the appropriate values of the specularity coefficient. The hydraulic gradient is found to be positively correlated with the specularity coefficient; in addition, it is more sensitive to the specularity coefficient when the specularity coefficient is less than 0.1. The appropriate value of the specularity coefficient decreases with the flow velocity and increases with the solid volume fraction. In the range of flow conditions considered, the findings may be used as a reference for future simulations in the research field of slurry transport.

Two-phase modelling for sediment water mixtures above the limit deposit velocity in horizontal pipelines

Abstract In dredging applications, deep sea mining and land reclamation projects typically large amounts of sediments are transported through pipes in the form of hyper concentrated (40% sediment or more) sediment-water mixtures or slurries. In this paper it is investigated how well a generic Euler-Euler CFD-model is capable to model velocity, concentration profiles and the pressure gradient of sediment above deposition limit velocity in a pipeline. This Euler-Euler solver treats both phases as a continuum with its own momentum and continuity equations. The full kinetic theory for granular flows is accounted for (no algebraic form is used) and is combined with a buoyant k-ε turbulence model for the fluid phase. The influence of the mesh size has been checked and grid convergence is achieved. All numerical schemes used are of second-order accuracy in space. The pressure gradient was calibrated by adjusting the specularity coefficient in one calibration case and kept constant afterwards. Simulations were carried out in a wide range of slurry flow parameters, in situ volume concentration (9–42%), pipe diameter (0.05–0.90 m), particle diameter (90–440 μm) and flow velocity of (3–7 m/s). The model shows satisfactory agreement to experimental data from existing literature.